Advances in Medical Sciences 66 (2021) 52–71

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Advances in Medical Sciences

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Review article Essential roles of the dystrophin-glycoprotein complex in different cardiac pathologies

Isela C. Valera a, Amanda L. Wacker a, Hyun Seok Hwang a, Christina Holmes b, Orlando Laitano a, Andrew P. Landstrom c,d, Michelle S. Parvatiyar a,* a Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA b Department of Chemical and Biomedical Engineering, Florida A&M University-Florida State University College of Engineering, Tallahassee, FL, USA c Department of Pediatrics, Division of Cardiology, Duke University School of Medicine, Durham, NC, USA d Department of Cell Biology, Duke University School of Medicine, Durham, NC, USA

ARTICLE INFO ABSTRACT

Keywords: The dystrophin-glycoprotein complex (DGC), situated at the sarcolemma dynamically remodels during cardiac Dystrophin-glycoprotein complex disease. This review examines DGC remodeling as a common denominator in diseases affecting heart function and Genetic cardiomyopathies health. Dystrophin and the DGC serve as broad cytoskeletal integrators that are critical for maintaining stability of Muscular dystrophies muscle membranes. The presence of pathogenic variants in genes encoding proteins of the DGC can cause absence Cardiac injury and regeneration of the protein and/or alterations in other complex members leading to muscular dystrophies. Targeted studies Acquired cardiomyopathies have allowed the individual functions of affected proteins to be defined. The DGC has demonstrated its dynamic function, remodeling under a number of conditions that stress the heart. Beyond genetic causes, pathogenic processes also impinge on the DGC, causing alterations in the abundance of dystrophin and associated proteins during cardiac insult such as ischemia-reperfusion injury, mechanical unloading, and myocarditis. When considering new therapeutic strategies, it is important to assess DGC remodeling as a common factor in various heart diseases. The DGC connects the internal F-actin–based cytoskeleton to laminin-211 of the extracellular space, playing an important role in the transmission of mechanical force to the extracellular matrix. The essential functions of dystrophin and the DGC have been long recognized. DGC based therapeutic approaches have been primarily focused on muscular dystrophies, however it may be a beneficial target in a number of disorders that affect the heart. This review provides an account of what we now know, and discusses how this knowledge can benefit persistent health conditions in the clinic.

1. Introduction transcripts (14-Kb) that each contain a unique first intron and spliced to share the remaining 78 exons [3]. In cardiomyocytes, the dystrophin 1.1. Dystrophin and the dystrophin-glycoprotein complex isoforms Dp427 and Dp71 are expressed in contrast to skeletal muscle that expresses only Dp427 (Byers TJ, Leiden Muscular Dystrophy Pages: 1.1.1. Dystrophin Dystrophin isoforms, http://www.dmd.nl/isoforms.html, Mar 5, 2006). Dystrophin is a major component of the subsarcolemmal scaffold of Dystrophin associates with a number of peripheral and membrane-bound muscle cells. It is a large rod-shaped cytoskeletal protein with four main proteins designated as the dystrophin-glycoprotein complex (DGC). functional domains that is localized at the cytoplasmic side of the Identification of the integral components of the DGC was defined on the sarcolemma [1,2]. Dystrophin is encoded on the X chromosome (Xp21) basis of four distinct biochemical and cellular characteristics, which in a large gene designated as DYS1. It spans a total of 79 exons and has eliminated less-tightly bound proteins such as caveolin-3 (Cav-3) [4] and seven promoters known to initiate dystrophin transcription. Three of the neuronal nitric oxide synthase (nNOS) [5]. A related protein, utrophin, is promoters are located at the 5’ end of the gene: (B) brain, (M) muscle, an autosomal homologue of dystrophin that is expressed ubiquitously and (P) purkinje promoters generate full length dystrophin protein and earlier in development than dystrophin that is not localized at the

* Corresponding author. Department of Nutrition, Food and Exercise Sciences, Florida State University, 107 Chieftan Way Biomedical Research Facility 238, Tal- lahassee, FL, 32306-1490, USA. E-mail address: [email protected] (M.S. Parvatiyar). https://doi.org/10.1016/j.advms.2020.12.004 Received 1 July 2020; Received in revised form 12 December 2020; Accepted 17 December 2020

1896-1126/© 2020 The Authors. Published by Elsevier B.V. on behalf of Medical University of Bialystok. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.org/licenses/by-nc-nd/4.0/). I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 sarcolemma of mature cardiomyocytes [6]. Utrophin has been found to changes may become a chronic maladaptation. A study by Kaprielian be expressed at the sarcolemma in dystrophinopathies, a group of dis- et al. [31] utilized single- and double-label immune-confocal microscopy orders arising from a lack of dystrophin [7]. A schematic is provided in and high-resolution immunogold fracture-label electron microscopy and Fig. 1 for visualization of the proteins of the DGC and associated proteins identified a population of dystrophin that partially colocalizes with that will be highlighted in this review. costameric vinculin in non-diseased and hypertrophied myocytes but is Dystrophin loss has an important role in cardiomyocyte destabiliza- lost in degenerating cells. In contrast to studies performed in rat car- tion, causing membrane instability and increased cell permeability [8,9]. diomyocytes, the dystrophin network in human cardiomyocytes is This suggests that dystrophin plays a primarily mechanical role in enriched at costameres [31,32]. Costameric distribution of cardiac DGC maintenance of cell membrane integrity. Numerous studies have as well as colocalization with proteins of the vinculin-talin-integrin sys- enumerated the connection between loss of dystrophin and development tem at the sarcomeric region that aligns with sarcomeric I bands suggest a of contractile dysfunction in the failing heart and progression to heart force transductive role for the cardiac DGC [32]. The presence of dys- failure [10–13]. After pressure overload is introduced in mice by aortic trophin in cardiac T-tubule membranes but not in skeletal muscle sug- constriction, dystrophin mRNA is significantly increased, which is gests that dystrophin has even more roles in defining the organization of anticipated to be an adaptive measure to preserve sarcolemma integrity membrane domains [31]. In a study using DMD-null mice (lacking Dp427 [14]. The fundamental structural role of dystrophin in the heart can be and Dp71 dystrophin isoforms) compared to mdx mice (lacking Dp427 seen by the development of dilated cardiomyopathy (DCM) in genetic but expressing Dp71) it was shown that cardiomyopathy develops pri- diseases caused by the reduction or loss of dystrophin protein expression marily due to a loss of full-length Dp427. It was also shown that Dp427 is e.g. Becker muscular dystrophy (BMD), Duchenne muscular dystrophy present in the cardiac sarcolemma and T-tubules, whereas Dp71 is spe- (DMD) and X-linked DCM respectively [11,15]. Loss of dystrophin from cifically only localized at the T-tubules [33]. Dystrophin remodeling the sarcolemma has been observed in a number of different cardiomy- occurs in end-stage human heart failure [34] and is increased in hyper- opathies caused by vastly different etiologies including post-viral trophied T-tubules [31]. In heart failure, remodeling of T-tubules has myocarditis [16], myocardial infarction [17], septic cardiomyopathy been found accompanied by increased wheat germ agglutinin (WGA) [18], induced Chagas disease [19,20] and several pharmaceuticals labeling, a lectin known to bind to glycosylated proteins in the DGC. including the beta-adrenergic agonist isoproterenol [21,22] and Along with these changes, a large increase in type IV collagen (Col-VI) chemotherapy drug doxorubicin [23]. These distinct cardiomyopathies abundance was detected in the T-tubule lumen and by displaced sarco- involve cleavage of dystrophin and other cytoskeletal and sub- lemmal labeling of dystrophin [35]. Therefore, dystrophin and collagen membranous proteins by proteolytic enzymes such as calpains [10,13,17, remodeling in the ventricles appear to be fundamental steps along the 26,27], causing - disappearance of these proteins from the sarcolemma path to heart failure. This demonstrates that alterations in both extra- [24–26]. Additional studies indicate that the N-terminus of dystrophin is cellular and intracellular myocardial architecture represent a wide range cleaved in the failing heart, leading to contractile dysfunction and DCM of targets to reverse classical pathological remodeling of the heart. [28,29]. At high doses, isoproterenol causes disruption of dystrophin and Collectively, these findings suggest that dystrophin provides important its translocation from the sarcolemma to the myoplasm [21]. Several structural support to the heart and is remodeled along with alterations in studies have shown that dystrophin loss can be detected prior to devel- its dynamic function. Understanding how these changes in dystrophin opment of cardiac systolic and diastolic dysfunction [30]. Therefore, it is distribution influence development of heart failure will reveal new reasonable to conclude that early intervention for dystrophin loss could strategies to reverse remodel pathological changes before they reach in fact prevent precipitous cardiac decline caused by a diverse number of permanence. cardiac insults. While not a specific function of dystrophin, it appears that dystrophin The distribution of dystrophin changes under circumstances that is necessary for the proper maintenance of the cytoskeleton, which has an induce wall stress, therefore, it appears that alterations in dystrophin essential role in cellular responsiveness to mechanical signals. The dys- abundance may be responses to acute stress, however over time, these trophin rod domain contains spectrin-like repeats that are required for

Fig. 1. The Cardiac Dystrophin-Glycoprotein Complex. In the heart, the DGC is comprised of dys- trophin (purple), a large cytoskeletal protein that links cytoplasmic actin with the transmembrane and pe- ripheral DGC components. The dystrophin C-terminus associates with β-dystroglycan (mauve) at its C-ter- minus associates with filamentous F-actin. Dystrogly- can consists of 2 subunits, α and β, that are products of the same gene (mauve). Dystroglycan connects with the extracellular matrix by binding to laminin-211. The sarcoglycan complex (light purple) is composed of 4 subunits: α-, β-, γ-, and δ-sarcoglycans. Sarcospan is a tetraspanin-like protein that forms a subcomplex with the sarcoglycan complex. Additional sub- complexes in the cardiac muscle DGC include α dys- trobrevin (blue), the α and β syntrophins (purple), nNOS (dark blue), and caveolin 3 (periwinkle). Caveolin-3 is able to directly bind to nNOS and pro- vides a separate link to the plasma membrane. The major α/β integrin subunits (blue) are important in mechanotransduction and membrane stabilization, however not part of the DGC. Figure created using BioRender.com.

53 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 microtubule lattice organization [36,37]. Striated muscles have been proteins, metabolic enzymes, detoxification enzymes, basal laminal shown to possess mechanotransductive X-ROS signaling that integrates proteins, contractile proteins and ion-handling proteins [49]. Studies contraction-induced mechanical stress or stretch with ROS generated by such as these provide insight that distinct protein associations may un- NADPH Oxidase 2 (NoX2) that then targets calcium signals [38–41]. In derlie disease presentations of dystrophin mutations in cardiac versus the mdx mice, detyrosination, a post-translational modification (PTM) of skeletal muscle. Additional roles for the DGC include cellular signaling, α-tubulin, influences X-ROS. In vitro experiments have shown that the mechanotransduction and cellular adhesion. When highlighting the role pharmacological reduction of detyrosination ablates aberrant X-ROS and of dystrophin in disease, the most prominent is the severe childhood þ Ca2 signaling to protect against increased workload effects including muscle wasting disorder - DMD. However, it is increasingly evident that cardiac arrhythmias. Therefore, microtubule detyrosination in the mdx dystrophin and its associated proteins have important roles in main- mice may be a source of cytoskeletal stiffness and mechanotransduction taining cardiac health and compensating for systemic changes in the in striated muscle [41]. In the heart, the subcellular distribution of dys- body including metabolic alterations (e.g. diabetes and cachexia) [50, trophin is not preferentially associated with costameres or any sarco- 51], cardiac function (e.g. heart failure and cardiomyopathies), injury meric regions. Therefore, dystrophin in the myocardium has not been response (e.g. ischemia-reperfusion and regeneration), myocarditis (e.g. found to be a distinctive component of the costamere [42], however it Coxsackie and trypanosoma infections). While there are clear conse- localizes to the costamere in response to cardiac insult [43]. These al- quences of the absence of dystrophin in the dystrophic heart, the terations in localization may alter the connection of dystrophin and fundamental role that dystrophin plays in the heart is much less known. associated proteins with the cytoskeleton as well as the sarcomere by The transmembrane protein dystroglycan (DG) was first discovered as altering the strength of costameric connections with the proteins at the a component of the DGC in skeletal muscle membranes [52]. Its role in Z-line [43]. the DGC is primarily one of providing a vertical connection between Overall, these and other studies demonstrate that disruption of dys- cytoskeletal proteins and the extracellular matrix (ECM). In humans, the trophin can culminate in heart failure, independent of whether heredi- proteins α-DG and β-DG are transcribed from the same gene DAG1. The tary or acquired factors are responsible. Irrespective of the causes of peptide that is generated becomes proteolytically cleaved to produce two dystrophin loss, it sets up a vicious cycle of increased sarcolemma separate, distinct yet interacting proteins of the DGC [53]. The α-DG instability/permeability, calpain activation and translocation/ cleavage protein is situated at the extracellular membrane and consists of two of dystrophin in the myoplasm. In the failing heart, ventricular remod- globular domains connected by a mucin domain [54]. Additional features eling involves alterations in both the extracellular and intracellular ar- of α-DG include three putative N-glycosylation sites in the N- and chitecture of the myocardium and changes in collagen deposition and C-termini that may contribute to laminin binding [52]. Moreover, increased cardiomyocyte hypertrophy. glycosylation of O-linked sugars by LARGE, within the mucin domain, appears to be necessary and sufficient for laminin binding [55]. An 1.1.2. Dystrophin-glycoprotein complex essential function of α-DG is that it serves as a receptor for extracellular The DGC plays an essential role in maintaining cardiac muscle ligands including laminins, perlecan and agrin [56,57]. integrity. Straub et al. [44] found through extensive analysis that the The SGs form a subcomplex within the DGC and are N-glycosylated DGC is present in both striated (cardiac and skeletal) and smooth muscle. transmembrane proteins. There are six SG proteins denoted α through ζ. Most of the comprehensive early studies of the DGC were performed in The SGs are either designated as type I, transmembrane proteins with an skeletal muscle and more recently differences in cardiac muscle are being amino-terminus hydrophobic signal sequence (α- and ε-SGs) or type II appreciated. Dystrophin in striated muscle establishes the link between transmembrane proteins (β-, γ-, δ- and ζ-SGs). In striated muscle, the dystroglycan at the sarcolemma and actin of the cytoskeleton [45]. The major SG complex is composed of α-, β-, γ-, and δ-SGs, whereas in DGC consists of peripheral and transmembrane proteins that connect the vascular smooth muscle, the major complex consists of ε-, β-, δ-, and extracellular matrix (ECM) with the intracellular cytoskeletal network. ζ-SGs [8]. In addition to the core subcomplex above, two additional SG Located on the extracellular side is alpha-dystroglycan (α-DG); the have been identified, the broadly expressed ε-sarcoglycan (ε-SG) [58,59] transmembrane proteins are beta-dystroglycan (β-DG), sarcoglycans (SG) and the novel zeta-sarcoglycan (ζ-SG) related to γ-SG and δ-SG [60]. A and sarcospan (SSPN); and proteins on the cytoplasmic side are dystro- study by Bonneman€ et al. [61] suggests that β-SG has a principal role in phin, dystrobrevin, syntrophins and less tightly associated Cav-3 and maintenance and/or assembly of the SG complex in striated muscle. The nNOS. The DGC is hypothesized to predominately act as a membrane transmembrane SG glycoprotein subcomplex is laterally fixed to the stabilizer and provide structural support to contracting muscles to protect dystrophin axis [62] and also associates with two muscle-specific α7 and them from contraction-induced damage [47]. β1D integrins [63–65]. While primarily biochemical approaches have been used to charac- SSPN was the last protein of the DGC to be characterized and this terize the DGC, newer studies have utilized immunoprecipitation and transmembrane protein shares homology with the tetraspanin protein shotgun proteomics to identify dystrophin-associated proteins. One family, therefore it is predicted to have four transmembrane domains and striking difference between skeletal muscle and cardiac muscle is that the a large extracellular loop [66]. SSPN preferentially associates with the SG β1-syntrophins are much less abundant in the heart. Cardiac dystrophin subcomplex and the SG-SSPN subcomplex assists in stabilizing α-DG in immunoprecipitations identified disease-causing proteins including striated muscle [42,62]. SSPN also has been shown to associate with Cavin-1 (PTRF), Ahnak1 (desmoyokin), Cypher (LDB3, ZASP) and α7β1 integrin [67] and promote cellular adhesion through incompletely Crystallin alpha B (CRYAB) that were not found in skeletal muscle [48]. understood mechanisms [68,69]. An SSPN-deficient mouse model was Additional mass spectroscopy profiling of whole heart preparations developed by Lebakken et al. [70] and did not exhibit an obvious revealed that the molecular pathogenesis of DMD-associated cardiomy- phenotype, although later studies showed that hearts of these mice were opathy is more complex than previously appreciated. In this study, the functionally unresponsive to isoproterenol [69]. Overexpression of SSPN mdx-4cv mouse model was used instead of the mdx mice because of its in DMD mouse hearts (mdx and mdx:utr-het) causes remodeling of the low frequency of revertant dystrophin-expressing fibers. An interaction DGC, increasing its abundance, thereby stabilizing the sarcolemma and map was generated for proteins in the mdx-4cv heart, which showed that preserving cardiac function [71]. Intriguingly, SSPN may play a role in loss of full-length cardiac dystrophin (Dp427) caused drastic reductions heart development, whereby it interacts genetically with the transcrip- in α1-syntrophin, α-SG, β-SG and δ-SG. It was also found that loss of tion factor Nkx2-5 during the formation of the ventricular septum [72]. these protein associations undermined the proper linkage between dys- The syntrophin complex and dystrobrevin at the cytoplasmic aspect of trophin Dp247 and laminin and may cause secondary abnormalities that the DGC appear to have an important scaffolding role for anchoring prime the heart for cardiomyopathic development. Overall, the abnor- mediators of signaling. The syntrophins are a multigene family consisting malities found were related to reduced expression of mitochondrial of five heterogeneous adaptor proteins that share a common domain

54 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 structure [73]. The syntrophins have been shown to bind directly to DGC Table 1 proteins: dystrophin and α-dystrobrevin [74]. Their association with the Diseases with cardiac presentations that cause remodeling of the dystrophin- DGC and interaction with nNOS [75], aquaporin-4 [76], ion channels glycoprotein complex. [77] and a number of kinases [78] strongly suggest that the syntrophins Condition DGC Proteins Etiology References function as modular adaptors. The localization of nNOS to the DGC in the Heart Failure ↑ N-term Multiple [34,90,103, heart has been less well characterized. A study by Gonzalez et al. [79] Dystrophin, ↓ 104] uncovered a novel pattern of nNOS localization to intercalated discs that β-sarcoglycan corresponded with areas of high utrophin expression but low dystrophin Right Ventricular ↓ β-dystroglycan, ↓ Multiple [161] failure Ɣ-sarcoglycan and syntrophin expression. In the mdx mice, nNOS localization shifts to ↓α -/- Left ventricular non -dystrobrevin Nonsense variant [88] the lateral sarcolemma and is even more punctate in mdx:utr mice compaction α-dystrobrevin lacking both dystrophin and utrophin. This study reveals that localization LVAD-Unloading ↓ Dystrophin, β1D- Bridge-to- [186–188] of nNOS to intercalated discs is necessary for cardiac health and nNOS integrin transplant mislocalization is associated with DMD cardiomyopathy [79]. The role of X-linked Dilated Dystrophin loss Frameshift [90,106] Cardiomyopathy mutations nNOS in the heart has been determined to be functional rather than (XLDCM) structural and it is anchored to syntrophins via corresponding PDZ do- Ischemia/ ↓ Dystrophin, Thrombosis [43,164, mains [79]. Another study has demonstrated that the DGC serves as a Reperfusion Injury retention of DGC 166] mechanosensor and regulates nNOS activity in the heart and found that Atrial Fibrillation ↓ Dystrophin, nNOS ↑ miR-31 in atria [216,217] impaired stretch-dependent NO signaling in dystrophin-deficient car- mislocalization Progressive ↓ Dystrophin, DGC, Muscular [2,137,158, diomyocytes depends on AMPK signaling [80]. Lastly, the dystrobrevins Cardiomyopathy α-dystroglycan Dystrophies 160] belong to the dystrophin protein family and the dystrobrevin alpha iso- glycosylation, DMD, CMD form is encoded by the DTNA gene [81]. Dystrobrevins are hydrophilic Truncated phosphoproteins that bind to dystrophin [82] and syntrophin [74], but Dystrophin Vasospasm ↓ δ-sarcoglycan, Limb-Girdle MD [281] also to the SG-SSPN complex [83]. Cav-3 is a scaffolding protein that β-sarcoglycan, β binds to the C-terminus of -DG and appears to compete with SSPN dystrophin-binding [84]. Other proteins have been found to bind to Cachexia/Atrophy ↓ Dystrophin Cancer [51] β-DG, thereby extending its functional influence including the adaptor Arrhythmias ↓ Dystrophin Muscular [198] protein growth factor receptor-bound protein 2 (Grb2). Interactions be- Dystrophy Acquired ↓ Dystrophin Cardiotoxicity [23] tween DG-Grb2 promote ERK-MAP kinase activity. Additional functions Cardiomyopathy/ (anthracyclines) have been elucidated including a role for β-DG in organizing acetylcho- Myocarditis ↓ Dystrophin, Sepsis/shock [18] line (ACh) receptors. Rapsyn, a Src-like kinase, binds to β-DG and pro- β-dystroglycan motes ACh receptor clustering at nerve synapses [85]. A list of disorders Cleavage of Coxsackievirus B3 [238,241, ↓ shown to impact the DGC in the heart is summarized in Table 1. Dystrophin, 254,255, β-sarcoglycan 257] ↓ Dystrophin Trypanosoma cruzi [19,262] 2. Review Abbreviations: DGC - dystrophin-glycoprotein complex; N-term Dystrophin – N- terminus Dystrophin; SSPN – sarcospan; β1D-integrin – beta1D-integrin; nNOS – 2.1. Genetic diseases of the DGC that affect the heart neuronal NOS; LVAD – left ventricular assist device; miR – microRNA.

Cardiomyopathies are a group of multifactorial diseases, character- dystrophin-deficient mdx hearts is that both α-DG and β-DG are retained ized by enlargement and thickening of the heart muscle. Traditionally, at the cardiac sarcolemma, whereas both proteins are largely absent from cardiomyopathies have been classified based upon morpho-functional dystrophin-deficient skeletal muscles [46]. Mutations in the X-chromo- characteristics into dilated cardiomyopathy (DCM), hypertrophic car- some encoded dystrophin gene (DYS) cause a group of dystrophino- diomyopathy (HCM) and restrictive cardiomyopathy (RCM); or based on pathies, the most common of which is DMD with an incidence of their etiology as they can be acquired or inherited [86]. 1/3600–6000 male births, but also includes X-linked dilated cardiomy- Disease-associated mutations of the DGC underlie the degeneration of opathy with no muscle weakness and subclinical skeletal muscle striated muscle and have been implicated in the pathogenesis of several involvement [1]. BMD is an allelic disorder with milder disease presen- inherited and acquired myopathies. In cardiac muscle, the DGC includes tation than DMD that can also manifest with DCM and occurs in 1/18,000 dystrophin and the dystrophin-associated glycoproteins α-, β-, γ-. and male births [89]. Dystrophinopathies are caused by various types of δ-SG; α- and β-DG; and SSPN. Much is known about the function of the mutations including missense, nonsense, insertion, deletion, or duplica- DGC due to the existence of disease-causing mutations in DGC proteins tion in the DMD gene leading to out-of-frame mutations that alter the that disrupt essential functions or interactions. Mutations in dystrophin reading frame (no functional protein ¼ DMD) or maintained reading and the SGs are linked to human diseases that have cardiac manifesta- frame ending at a premature stop codon (truncated but functional pro- tions. Causes of primary dystroglycanopathies however, are rare and are tein ¼ BMD). X-linked cardiomyopathies are mostly associated with 2 generally related to defects in posttranslational processing of the types of dystrophin gene defects: 1. proximal - involving either muscle alpha-subunit, maturation of the precursor protein or also in the overall promoter or early exons; or 2. Becker-type - affecting rod domain exons. stability of the two dystroglycan subunits [87]. Besides its association From studies in X-linked DCM and DMD-associated cardiomyopathy, it is with dystrophin, a nonsense mutation in α-dystrobrevin has been linked clear that loss of dystrophin in the heart leads to progressive disease of with multigenerational incidence of left ventricular noncompaction the myocardium that diminishes function and ultimately leads to heart (LVNC) cardiomyopathy in a Japanese family [88]. failure [90], beginning first with abnormalities in diastolic function [91]. Substantial diversity exists in the cardiac presentation of dystrophino- 2.1.1. Dystrophinopathies pathies suggesting that multiple layers of regulatory processes are Dystrophinopathies represent a group of genetic disorders resulting involved in disease presentation [92]. Clinical manifestations of DCM from the lack of dystrophin, which causes DGC destabilization and cardiomyopathy include ventricular dysfunction, arrhythmia and reduced force transmission in different types of striated muscle. Defi- congestive heart failure [93–95]. Also, myocardial fibrosis is a dis- ciency of dystrophin in myocytes causes sarcolemma instability, loss of tinguishing feature that exacerbates diastolic relaxation and increases the cellular integrity, increased vulnerability to contraction-induced injury incidence of arrhythmias. In one clinical study [96], arrhythmias were that leads to muscle degeneration [47]. A distinctive difference in

55 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 detected in 44% of DMD and 57% of BMD patients and found associated ventricular (LV) dilated cardiomyopathy (DCM) is nearly ubiquitous in with decreased cardiac function. Arrhythmias contribute to sudden car- patients with DMD. DMD-associated cardiomyopathy is a disease char- diac death (SCD) in DMD patients and dystrophin loss in the heart can acterized by ventricular dilatation and impaired systolic function, which precipitate atrial and ventricular premature beats, atrial tachycardia, is the leading cause of cardiac death in these patients [95]. To better ventricular couplets as well as non-sustained and sustained ventricular understand the factors affecting DMD hearts, a study in the mdx mice tachycardia (VT). The incidence of VT is strongly correlated with revealed that skewed X chromosome inactivation in female mdx-XistΔhs decreased ejection fraction (EF) [96–98]. Some female carriers have been mice allowed mosaic expression of low levels (3–15%) of full-length found to present in their 4th or 5th decade of life with slowly progressing dystrophin. Even this small amount of dystrophin expression was able DCM that is frequently diagnosed later in life. This indicates that even to delay the onset of cardiomyopathy and heart failure [100]. Therefore, subthreshold changes in dystrophin and DGC composition can lead to important questions about dystrophin restoration therapies can be dysfunction although within a different temporal window. answered by examining the hearts of female DMD carriers that exhibit mosaic cardiac dystrophin. Furthermore, in a clinical study it was found 2.1.1.1. Duchenne muscular dystrophy. The complete loss of muscle that pre-clinical myocardial involvement existed in 84.3% of the 166 dystrophin causes DMD with an incidence between 1 in 3600–6000 male cases of BMD and DMD patients. In addition, immunohistochemical births. DMD disease typically presents in the early childhood and is first analysis of endomyocardial biopsies revealed dystrophin abnormalities evident as a delay in muscle-dependent milestones, difficulty/loss of in the membranes of myocardial fibers [101]. A study examining sus- ambulation followed by cardiac and respiratory issues [99]. Left ceptibility of female carrier hearts expressing slightly greater than 50%

Fig. 2. Genetic Cardiomyopathies Associated with DGC Proteins. (A) In Becker-type muscular dystrophy, pathogenic mutations lead to production of truncated dystrophin proteins and cardiac presentation may not appear until mid-life. Increased transparency of the DGC indicates partial loss or destabilization of the complex. Becker patients have skeletal muscle involvement generally manifesting as muscle weakness and heart involvment including DCM. (B) In X-linked cardiomyopathies, pathogenic mutations cause absence of the dystrophin protein in heart muscle, whereas skeletal muscle remains unaffected. The DGC is shown with increased transparency to indicate destabilization of the complex in the absence of dystrophin in the heart. Utrophin compensates partially for loss of dystrophin. X-linked cardiomyopathy causes development of myocardial fibrosis, cardiac remodeling and development of heart failure. (C) In dystroglycanopathies, the pathogenic mu- tations typically occur in glycosyltransferases in the O-linked glycosylation pathway. These glycosylases are responsible for producing the full matriglycan normally present on alpha-dystroglycan (α-DG) that binds to laminin in the extracellular matrix (ECM). These diseases present as muscular dystrophies with various skeletal muscle manifestations and can also have cardiac involvement. (D) Sarcoglycanopathies are recessively inherited autosomal diseases. They occur due to pathogenic mutations in one of the subunits (α,β,δ,γ) of the sarcoglycan complex. Pictured is an example of DGC remodeling that occurs in beta-sarcoglycanopathies. The dotted lines around all units of the sarcoglycan complex indicate that pathogenic loss of beta-sarcoglycan destabilizes the remaining sarcoglycans causing loss of the sar- coglycan complex from the sarcolemma. The types of sarcoglycanopathies are indicated in the right panel, according to gene names and severity of disruption of the sarcoglycan complex and the presentation of cardiomyopathic disease. Figure created using BioRender.com.

56 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 dystrophin found that they had significantlyincreased incidence of car- domain causes XL-DCM because it affects the stability of dystrophin by diac injury. These findings indicate that restoring dystrophin to increasing unfolding thereby, disrupting its overall structure. A 50 mu- approximately half of the cardiomyocytes in the heart, still rendered it tation in the dystrophin gene linked to XLCM has been found to cause vulnerable to injury [102]. Overall, it was suggested that stress-induced cardiac dystrophin deficiency but also a loss of α-DG membrane binding mortality was dependent on whether mothers were dystrophic or not. [113]. These findings provide insight that while dystrophin may be Therefore, even mice with equivalent dystrophin expression were found present, alterations in its stability and structure may drive XL-DCM to exhibit vastly different outcomes, thus arguing the case that epige- pathogenesis [114]. Recently other XL-DCM pathogenic mechanisms netic, development and environmental factors may play a role in the have been found, whereas the cardiac-specific knockout of the DOT1L vulnerability of dystrophic hearts [102]. These factors may need to be (disruptor of telomeric silencing 1-like) gene causes DCM. Further accounted for when implementing various therapeutic approaches that investigation revealed that DOT1L regulates dystrophin transcription and restore varying levels of dystrophin. stability by affecting histone methylation events in the mdx mice and DCM patient tissues thereby contributing to DMD [115]. Studies such as 2.1.1.2. Becker-type muscular dystrophy. The presence of truncated, yet these add novel insight into the pathogenesis of XL-DCM and bring partially functional dystrophin due to DYS gene mutations has been awareness that certain epigenetic factors may underlie myocyte suscep- described as the cause of BMD. BMD has an estimated incidence between tibility to damage as shown in heart failure caused by modifying factors 1 in 18,000–30,000 male births and generally causes slowly progressing, [116]. Other factors that may underlie overall cardiac presentation in varying disability in skeletal and cardiac muscles. In general, the age of XL-DCM dystrophin deficiency include telomere dysfunction, altered diagnosis may be later with most individuals surviving into mid-to-late protein-protein interactions [49], and post-translational modifications adulthood. DCM is the principal cause of death in BMD patients [103, [117,118]. 104]. In a recent case report, a BMD patient developed severe DCM by the In the dystrophinopathies classified above, dystrophin deficiency age of 29 and the genetic cause was found to be a hemizygous c.264 þ 1G causes sarcolemma instability and the formation of microtears in the cell > A mutation in intron 4 of dystrophin in both skeletal and cardiac membrane. This allows unregulated passive calcium entry into the cell 2þ muscles. Both immunohistochemistry and western blot analyses revealed and therefore, activation of protein channels e.g. L-type Ca channels decreased amounts of truncated dystrophin in skeletal muscle but nearly (LTCC) that regulate calcium entry into cardiomyocytes, transient re- normal cardiac expression of the truncated dystrophin. This indicates ceptor potential (TRP) channels and mechanical stretch-activated ion that severe cardiac dysfunction in BMD patients may still manifest even channels at the sarcolemma [119–121]. All of these factors further in hearts that are expressing nearly normal levels of truncated dystrophin complicate the maintenance of appropriate intracellular calcium levels. [105]. Findings such as this provide insight into the degree of dystrophin These alterations lead to increased intracellular calcium levels, conse- restoration necessary to protect the hearts of both BMD and DMD pa- quently activating calpains and proteases that degrade contractile pro- tients. See Fig. 2A showing truncated dystrophin and disruptions in DGC teins and promote cellular death and fibrosis [122]. Hearts from the mdx proteins found in BMD. mice exhibit high diastolic calcium levels, increased stretch-induced calcium influx, altered calcium transients and calcium handling [123, 2.1.1.3. X-linked dilated cardiomyopathy. From X-linked DCM (XL-DCM) 124]. The dystrophin-deficient heart is even more susceptible to myocyte studies, it is clear that loss of dystrophin in the heart leads to progressive loss than skeletal muscle for several reasons including heightened acti- disease of the myocardium that diminishes function and ultimately cul- vation of calcium-induced-calcium-release (CICR) and the much lower minates in heart failure. A number of mutations that cause XL-DCM occur regenerative capacity of cardiac muscle [125–127]. Calcium-overload in in the “hot spot” region spanning from exons 45–55. Several hypotheses cardiomyocytes triggers cell death due to multiple adaptations including have been put forward to explain cardiac specific manifestations from mitochondrial calcium uptake, elevated mitochondrial calcium content, mutations in full-length dystrophin isoforms that exist in muscle, brain swelling, and interruption of ATP synthesis [128]. and cerebellar-Purkinje-cell isoforms: 1) differences exist in transcrip- tional regulation of dystrophin mRNA between skeletal and cardiac 2.1.2. Dystroglycanopathies muscles, or 2) differences in mutations may affect cardiac specific sta- Dystroglycanopathies are a heterogeneous group of neuromuscular bility of dystrophin or its interactors, or 3) the phenomenon of use, disorders that arise from abnormal glycosylation and are generally whereby the dystrophin-deficient myocardium is more susceptible to caused by hypoglycosylation of dystroglycan. Loss of laminin-binding strenuous exercise than skeletal muscle [90]. XL-DCM was first reported capability by α-DG underlies the fundamental basis for its role in these in 1987 by Berko and Swift [106] in a large five generation family with diseases that cause muscular dystrophy and various brain and eye de- the diagnosis of 63 male members with DCM. The male patients were fects. Mutations in the α-DG gene DAG1 are rare, likely due to its essential between 10 and 20 years old and manifested rapidly progressing heart function and therefore expected embryonic lethality [55,129,130]. The failure, ventricular arrhythmias with no skeletal muscle involvement. first identified human α-DG T192 M mutation appears to negatively in- Subsequently, additional cases of XL-DCM were identified [107–109]. fluence steps necessary for DG maturation [55]. In general, See Fig. 2B for schematic regarding X-linked cardiomyopathy showing disease-causing mutations have been identified that cause secondary complete dystrophin loss and partial loss of DGC proteins. dystroglycanopathies, therefore the defect does not affect the primary Intriguingly, the pathogenesis of a number of XL-DCM mutations in- structures of α-DG or β-DG, but rather, the defects occur in the glyco- volves substitutions that ablate M isoform expression (50-XLDC) [110]. In syltransferases responsible for proper O-glycosylation of α-DG [131]. one XL-DCM family, significant downregulation of dystrophin-associated Genetic causes of dystroglycanopathies are primarily linked to variants in glycoproteins was detected in cardiac muscle although the Dp71 dys- up to sixteen glycosyltransferase genes including LARGE. These glyco- trophin isoform was expressed in the cardiac tissue [111]. Franz et al. syltransferases act sequentially and are responsible for proper O-linked [112] reported a variant (C4148T) in the seventh codon of dystrophin glycosylation of the mucin domain located in the linker region of α-DG exon 29 that caused DCM. The cardiac phenotype of this gene variant was [132]. Dystroglycanopathies can occur with or without central nervous not due to a diminished expression of cardiac dystrophin. Further system involvement and can range from a mild to very severe presenta- investigation into the molecular mechanisms underlying this disorder tion [133]. In these disorders, nervous system and skeletal muscle subtype may be caused by a conformational change in the dystrophin manifestations occur more frequently than cardiac defects. Cardiac molecule. This conformational alteration may interfere with normal SG involvement is most common in Fukuyama congenital muscular dystro- assembly in the heart muscle but not in the skeletal muscle [112]. A phy (FCMD), congenital muscular dystrophy 1D (MDC1C), and Limb missense mutation Lys18Asn located in the N-terminal actin binding Girdle muscular dystrophy 2I (LGMD2I) that present after the first decade of life [134].

57 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71

The smaller β-DG protein is 43 kDa in size and is a single-pass Animal models have been developed to study the underlying mech- transmembrane protein that possesses putative N-glycosylation sites anisms of disease development in sarcoglycanopathies due to variants [135]. β-DG tightly associates with α-DG, and provides a strong anchor that cause the loss of individual SG complex subunits. Overall, the defi- for α-DG at the sarcolemma [136]. Mouse models have been generated ciency of δ-SG leads to the most severe form of cardiomyopathy amongst including one with a null allele (Dag1neo2) that was found to be em- this group of disorders. Variants in the human δ-SG (SGCD) gene have bryonic lethal and embryos exhibited disruption of basement membrane been characterized in patients with familial and sporadic cases of DCM organization [130]. Therefore, additional models have been generated without significant involvement of skeletal muscles. In addition, defi- including mice chimeric for α-DG loss and inducible α-DG knockout ciency of δ-SG causes concomitant loss of other SG subunits (α,β,γ), SSPN, mouse models. Loss of DG expression in cardiac myocytes and loss of DG and α-DG [149]. The BIO14.6 cardiomyopathic (CM) hamster, an auto- laminin-binding activity in myd mice is sufficient to cause a progressive somal recessive strain, was found to have a variant in the SGCD gene cardiomyopathy characterized by focal fibrosis. Michele et al. [137] [150]. Also, in a different strain of CM hamster with heart failure suggested that the function of DG as an extracellular matrix receptor in (CHF147) it was shown that apoptosis and necrosis play a role in the cardiac myocytes may have a primary role in preventing myocardial early deterioration of left ventricular function during the first 4 weeks of damage in young animals that often accumulates with age and causes life [151]. Another model of severe dilated cardiomyopathy, the TO-2 cardiomyopathic remodeling. A number of mouse models have been hamster [152] is missing the δ-SG promoter and subsequently sarco- developed that lack a specific glycosyltransferase that is essential for the lemma expression of other SGs. It exhibits an age-dependent increase in formation of a full length matriglycan. Overexpression of LARGE, which myocardial sarcolemmal permeability in situ that is caused by cleavage acts late in the O-mannose glycosylation pathway, can rescue laminin and translocation of dystrophin from the sarcolemma to the myoplasm. binding and functionally bypass defects in glycosylation in several These experiments revealed a close relationship between loss of dystro- congenital muscular dystrophies [138]. Elimination of the cardiac phin and reduced hemodynamic performance as well as a distinct cor- fukutin gene (Fktn) in mice, the causative gene for Fukuyama muscular relation between dystrophin levels and survival rate. In vivo transfer of dystrophy, caused marked reduction of αDG glycosylation and reduced the missing δ-SG gene to TO-2 hamsters ameliorated pathological abundance of DGC proteins from the sarcolemma. These changes could changes and improved disease prognosis. It was concluded that disrup- be documented at all developmental stages. Fukutin deficiency caused tion of dystrophin is not an epiphenomenon but a direct predecessor of cardiac dysfunction in later adulthood and after exposure to multiple heart failure progression [153]. Other factors lead to improved outcomes pathologic hypertrophic stressors. These findings suggest that membrane in sarcoglycanopathies, including hepatic growth factor (HGF), which fragility is not the only pathogenic factor driving disease presentation. induces a microenvironment favorable for extracellular matrix (ECM) Also, new findings in the heart suggest that fukutin is important for remodeling. A study investigating the therapeutic benefit of transfected maintaining normal myocyte physiology and golgi-microtubule networks HGF showed that it restored α-DG to the cardiac cell membrane [154]. [139]. Transfection of TO-2 hamsters, with the HGF gene significantly increased their life expectancy. Long-term HGF secretion methods may be able to 2.1.3. Sarcoglycanopathies maintain cardiac function by reducing myocardial fibrosis and cyto- Defects of the sarcoglycan transmembrane complex associated with skeletal protein reorganization in the DCM hamster model [154]. A dystrophin are the cause of a series of skeletal myopathies (limb-girdle γ-SG–deficient mouse model was generated that developed progressive muscular dystrophies, or “sarcoglycanopathies”), that have variable muscular dystrophy, pronounced cardiac muscle degeneration, and presentation in the heart. Sarcoglycanopathies are manifested in an reduced survival. These mice also had lower levels of β- and δ-SG staining autosomal recessive fashion although the clinical presentation is het- of muscle, but normal levels of dystrophin, DGs, and laminin-211. Other erogeneous, and severity and age of onset are quite variable [140]. The findings included elevated baseline CK levels suggesting that CK release incidence in the general population is not clearly defined. However, occurs by mechanisms other than mechanical injury [155]. variants in the SGCA gene are the most common, whereas mutations in Coral-Vazquez et al. [156] studied mice deficient in α-SG and δ-SG and the SGCD gene are the most infrequent [141]. The presence of the entire demonstrated that only δ-SG null mice developed severe cardiomyopathy SG complex is important and a defect in one SG subunit can destabilize with focal areas of necrosis by 3 months of age and death by 6 months of the entire SG complex and the closely associated protein SSPN. The age. A porcine SGCD knockout model with loss of δ-SG also exhibited a impact of SG mutations on the stability of the entire DGC has been widely concomitant reduction of α-, β-, and γ-SG expression in the heart. The delineated. In LGMD-2E and -2F patients, the genetic defects in β- and knockout pigs developed systolic dysfunction, myocardial tissue pathol- δ-SG, respectively, cause the loss of the entire sarcoglycan complex from ogy and were prone to sudden death [157]. It has been demonstrated that the sarcolemma, but also reduce the abundance of dystrophin and dys- combined deficiency of α- and ε-SG–containing complexes disrupts the troglycan [142]. Patients with LGMD-2D have disease-causing mutations cardiac DGC complex causing development of a more severe cardiomy- in α-SG which subsequently cause the loss of β and δ-SG with a substantial opathy than caused by the loss of α-SG alone, suggesting that ε-SG is able reduction of γ-SG. These patients also exhibited a reduction of β-DG and to compensate for α-SG loss and prevent cardiomyopathy [158]. The dystrophin sarcolemmal expression [142–145]. Deficiency of γ-SG in β-SG–deficient mouse model exhibited progressive muscular dystrophy, LGMD-2C patients appeared not to destabilize the remaining sarcogly- muscular hypertrophy, severe elevations in CK (~100 times higher than cans at the sarcolemma and the DGC including dystrophin remained wild type), and cardiac fibrosis [159]. Cohn et al. [160] proposed a largely intact [146]. One consequence of SG mutations in these diseases pathogenetic mechanism for the cardiomyopathy associated with muta- is that any perturbations that cause the loss of the SG complex can expose tions within the β-orδ-SG genes, whereby disruption of the SG-SSPN β-DG to matrix metalloproteinase activity resulting in its loss from the complex in vascular smooth muscle perturbs vascular function by sarcolemma [147]. The SG complex is essential for maintaining mem- causing multiple vascular constrictions that damage the myocardium. brane integrity in contracting muscles and serves as a scaffold for mol- Expression of the other sarcoglycan ζ-SG was found to be reduced in ecules with important signaling roles [148]. Proposed mechanisms muscle with other SG gene mutations, therefore SGCZ mutations may underlying the pathogenic mechanisms that lead to sarcoglycanopathies indirectly potentiate membrane instability in other muscular dystrophies can be attributed to: 1) altered processing of defective SGs; 2) failure to caused by other DGC abnormalities [60]. assemble complete complexes; 3) ineffective cell membrane targeting of dysfunctional SG complexes. Analysis of sequences of missense variants 2.2. Remodeling of the DGC in the heart in the context of SG function suggests that mutant SG may be intercepted by quality control systems that compromise processing and instead lead 2.2.1. Heart failure to their disposal [148]. The loss of dystrophin has been shown to cause a sudden decline of

58 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 cardiac function and can lead to heart failure development. It remains right ventricular failure model [161]. It appears that hypoxic pulmonary incompletely understood whether DGC remodeling during cardiac stress hypertensive-induced neonatal right ventricular failure is associated with is a temporary adaptation that leads to long-lasting changes as the heart disorganization of the cytoskeletal architecture. It will be important to remodels and progresses to failure. In a study examining right heart establish whether unique myocyte cytoskeletal changes that accompany ventricular function, significant changes were found in the DGC of the heart failure in the neonatal period have important consequences for right ventricle of rats administered monocrotaline (MCT), an alkaloid understanding the postnatal myocardium and may provide important commonly used to induce pulmonary arterial hypertension, during guidance to physicians caring for newborn children [162]. development of right ventricular failure [161]. Changes in DGC proteins α-, β-, γ-SGs, β-DG and dystrophin in right ventricular tissue persisted for 2.2.2. Ischemia/reperfusion injury 8 wks post-MCT administration. It was also shown that α-SG was the most It has been shown that acute ischemic injury disrupts localization and sensitive to this stress compared to other SGs. These alterations in DGC even expression of distinctive groups of structural proteins present in proteins are suggested to underlie the genesis of heart failure in this cardiac myocytes that include the DGC, vinculin-integrins and spectrin model. It is anticipated that MMP2 and m-calpain readily present in all [163]. After a period of ischemia in the heart, during the reperfusion mammalian cells contributed to the decline in DGC complexes in this phase, sarcolemma dystrophin levels rapidly decline. This occurs during

Fig. 3. Heart Failure and Arrhythmia associated with the DGC. (A) Ischemia-reperfusion injury has been shown to impact the DGC with substantial decreases in sarcolemmal dystrophin expression and effects on other DGC proteins vary between studies. In a study by Yoshida et al. [17], after acute myocardial infarction, dystrophin (cleaved and intracellular localization), α- and β-sarcoglycan levels (depicted with increased transparency) are substantially reduced in viable tissues of the heart. (B) Hippo pathway and DGC interact to control cardiac regeneration. Cardiac regeneration occurs in neonatal cardiomyocytes (LEFT) when: (1) Hippo signaling is at low levels with reduced amounts of Yap phosphorylation and Yap-DGC binding. (2) Transcription of target genes, SGCD and α-catenin gene (CTNNA1), is activated by Yap-TEAD complex binding. (3) Expression of δ-sarcoglycan promotes DGC assembly. (4) In regenerative neonatal cardiomyocytes, the intercalated disc (ICD) is immature, and Yap promotes expression of α3-catenin, a component of the ICD. Cardiac regeneration is limited in non-regenerative adult cardiomyocytes (RIGHT) when: (1) Hippo signaling is active and at high levels, promoting Yap phosphorylation, thereby increasing Yap binding to the DGC. (2) Transcriptional activation by Yap-TEAD is reduced. (3) Phosphorylated Yap becomes sequestered by the DGC through an interaction involving the DG PPxY motif. (4) The ICD that forms in adult cardiomyocytes is mature and Yap incorporates into the ICD through binding to α-catenin independent of Hippo (Adapted from Morikawa et al. [176]). (C) Left ventricular assist device (LVAD) provides mechanical unloading of the heart. Proteins of the DGC and the cytoskeleton remodel in hearts. In the schematic, up and down arrows indicate proteins with increased or decreased expression in recovered patients between LVAD implantation and the time when heart would be explanted (Adapted from Birks et al. [186]). (D) Arrhythmias in dystrophin deficient hearts have been attributed to aberrant expression of the cardiac gap junction protein Connexin-43 (Cx43). Cx43 proteins normally form complete gap junctions at intercalated discs, however insufficient post-translational modifications (PTMs) in the absence of dystrophin may be responsible for lateralization of Cx43 to the sides of cardiomyocytes in humans and the mdx mice. At the lateral sides of car- diomyocytes, Cx43 forms unopposed hemichannels that disrupt ion gradients and increase susceptibility to isoproterenol-induced arrhythmias (Adapted from Him- melman et al. [208]). Figure created using BioRender.com.

59 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71

“myocardial stunning”, when contractile responsiveness is greatly (PI3K)-dependent restoration of dystrophin to the sarcolemma [168]. attenuated due to ATP depletion. These findings suggest that, dystrophin Overall, these studies examining the mechanisms that maintain dystro- localization at the cell membrane is an energy dependent process. A phin localization at the sarcolemma, even in the face of ischemic insult, certain proportion of dystrophin assumes an intracellular distribution, provide intriguing views of its utmost importance in maintaining con- which can be recovered over time [164]. Dystrophin depletion was tractile function in the heart. When examining IPC and IPost strategies, it coincident with a general reduction in transcription and translation and can be seen that protection of the myocardium from acute injury and was found to persist during reperfusion. DGC proteins that were most pathological processes may be able to preserve cardiac function. affected by ischemic injury or ischemia/reperfusion were dystrophin, β-DG and γ-SG. After acute myocardial infarction (AMI), wild type rats 2.2.3. Cardiac regeneration developed heart failure and were found to have reduced α- and β-SGs and It is well known that the mammalian heart exhibits poor regenerative dystrophin levels in the remaining viable tissue of the septum and left capacity and myocardial damage can initiate maladaptive pathways that and right ventricles. Therefore, it appears that an overall reduction in lead to heart failure. The heart is able to replace cardiomyocytes that functional DGC complex in “unaffected” tissues may be the origin of have met their demise due to normal aging and acute injury, however a contractile dysfunction in the failing heart. Ex vivo and in vitro findings precise understanding of cardiomyocyte turnover has remained elusive suggested that increased m-calpain activity may contribute to DGC due to disparate reports [169–172]. The cardiac regeneration field has destabilization after cardiac injury [17]. This phenomenon is depicted in been keenly interested in identifying factors that induce cardiomyocyte Fig. 3A. A related study indicates that long-term treatment of rats with proliferation in the post-infarct heart. In cardiomyocytes, the cytoskel- ACE inhibitor or AT1 receptor after left coronary artery-ligation pre- eton serves as a signaling hub that allows integration of intracellular and serves cardiac cell stability and contractile function by restoring α-SG and extracellular signals [173]. The membrane-associated cytoskeleton, maintaining sarcolemmal dystrophin levels [12]. In a related study, intercalated discs (ICDs) and the centrosome are specialized structures administration of isoproterenol to rats caused development of infarct-like associated with the cardiomyocyte cytoskeleton that have important myocardial lesions, and immunofluorescence studies visualized the loss functions in cardiomyocyte proliferation and maturation. The DGC and or reduction of dystrophin that occurs as part of the myocytolytic process integrin-vinculin-talin complexes play critical roles in transmitting [22]. In general, the loss of dystrophin leads to secondary instability of biomechanical signaling between the ECM, sarcolemma and sarcomere the remainder of the DGC [52]. It appears that the loss of these major [174]. Several key players dynamically regulate the rapid response of the structural complexes at the sarcolemma underlie the transition to irre- actin cytoskeleton to cellular cues including the Hippo pathway, a key versibility of myocardial ischemic injury in the cardiomyocyte [165]. regulator of cardiomyocyte proliferation [175], as shown in Fig. 3B. Since ischemia/reperfusion injury (IRI) results in such a dramatic It was discovered that dystroglycan, encoded by the DAG1 gene, is a depletion of dystrophin from the cardiomyocyte sarcolemma, it is central component of the DGC and serves as a signaling scaffold. It has rendered much more susceptible to mechanical force injury in the same been found that DG connects the evolutionally conserved Hippo signaling way as DMD hearts. A study by Kyoi et al. [43] showed that after 30 min pathway with the DGC [176] and postnatal mammalian heart regener- of ischemia, dystrophin was redistributed from the sarcolemma to the ation [177]. A past understanding of the role of Hippo signaling in the myofibril-containing fraction that is primarily composed of costameric heart has been that it regulates cardiac heart size during development cytoskeleton and intercalated discs. Beyond what was previously shown, [178]. Additionally, it has been shown that Hippo signaling is upregu- they found that reperfusion resulted in the loss of dystrophin from the lated in heart failure, and significantly, the dystrophin complex was membrane and myofibril fractions [166]. In an attempt to harness found to be downstream of the Hippo signaling pathway. In a related adaptive mechanisms in the heart, myocardial ischemic conditioning study by Leach et al. [179] it was demonstrated that abrogation of the strategies have been developed to protect the heart from prolonged Hippo pathway by genetic deletion of Salvador (salv) using short hairpin ischemia. These interventions can be delivered before, during or after RNAs (shRNA), at the time of infarct or after ischemic heart failure, ischemic insult and prevention of dystrophin loss from the sarcolemma improved systolic heart failure. was one of the strategies explored. Membrane dystrophin was completely Yap, an effector of the Hippo signaling pathway, was shown to restored in ischemic hearts when reperfused with 2,3-butanedione regulate cardiomyocyte proliferation in mice [176]. As cardiomyocytes monoxime (BDM), a contractile blocker, which appeared to protect the sense and interpret alterations in rigidity of the local microenvironment, ischemic heart, despite its recovery of contractile force. Based on these the subcellular localization of Yap is altered [180]. The structural and findings, a number of studies were directed toward determining whether functional integrity of the DGC is also important in controlling prolifer- there was a role for dystrophin in ischemic pre-conditioning (IPC). Since ation of cardiomyocytes. While DG binds directly to Yap to inhibit its dystrophin has a normal role of preventing oncosis in myocytes due to pro-proliferative functions, both the DG and the DGC are targeted by the physical and mechanical stressors, it was of interest whether dystrophin ECM proteoglycan agrin that promotes neonatal proliferation of car- could be an end target of IPC [43]. In vitro evaluation of mitochondria diomyocytes [181]. Agrin-stimulated proliferation of cardiomyocytes obtained from ischemic IPC rat hearts demonstrated increased ATP occurs following interaction with DG causing DGC disassembly and generation that has been shown important in relocalization of dystrophin release of Yap to the nucleus [181]. Yap regulates genes that encode to the sarcolemma. This increase in ATP production and sarcolemma components of two plasmalemmal complexes - the DGC and the dystrophin localization was inhibited by oligomycin and dinitrophenol talin-vinculin-integrin complex - which link the actin cytoskeletal (DNP), respectively, due to ATP synthase inhibition and proton iono- network to the extracellular matrix [32]. Plasmalemmal genes regulated phore activity. This suggests that enhanced relocalization of dystrophin by Yap include SGCD encoding δ-SG and TLN2, which encodes Talin 2 to the sarcolemma during the early phase of reperfusion could be participate in cytoskeletal remodeling and link the actin cytoskeleton to mechanistically linked to improvement of mitochondrial function and integrins and the ECM [182]. These findings can be related to the pre- protection against oncosis [43]. Since IPC is related to preservation of vious discovery that the mdx mouse hearts have reduced capacity for dystrophin at the membrane during ischemia and reperfusion, different regeneration and cytoskeletal remodeling but retain normal car- preconditioning strategies were employed that protected membrane diomyocyte proliferation after injury [183]. Yap directly binds to the DG structural integrity by enhancing restoration of dystrophin to the sarco- PPxY motif and exerts its inhibitory role to limit the proliferative capacity lemma including nicorandil (a mitochondrial KATP channel opener) of cardiomyocytes. The DG-Yap interaction was shown to be enhanced by [167]. A study by the Moriguchi laboratory investigated ischemic post- phosphorylation of Yap. Comparisons were made between the regener- conditioning (IPost) cardioprotective mechanisms and found that oncosis ative responses between Hippo-deficient postnatal mouse hearts and the was prevented by inhibiting contractile activity and infarct size was mdx hearts after injury. The Hippo-deficient postnatal mice; maintained limited by enhancing the phosphatidylinositol 3-kinase heart organ size and exhibited a normal corrective response to injury,

60 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 whereas the mdx – Hippo deficient mice response was over-proliferation duration of HF, LV size < 6.5 cm, creatinine levels <1.2 g/dl) associated of cardiomyocytes at the site of injury. Evidence of a nodal role of DGC in with recovery of myocardial function upon long-term unloading. mechanical signaling has certainly been established, however, it is still Furthermore, the RESTAGE-HF (Remission from Stage D Heart Failure) unclear how these signaling pathways impact the localization of Yap study found that 36% of enrolled patients experienced sustainable within cells [184]. Mechanical stressors appear to coordinate extracel- remission from HF syndrome following LVAD explantation [192]. These lular and mechanical signaling events and the negative regulatory loop studies provide an intriguing insight that gradual reloading of the heart Hippo-Yap-DGC is not functionally active in the stressed cardiomyocyte. may be effective in at least a subset of patients, although a number of Hippo signaling in the cardiomyopathic heart is a mechanism that is factors influence outcomes. For example, even if sustainable improve- activated during functional decline and appears to be maladaptive [176]. ments can be obtained for myocardial function, abnormalities in ven- Harnessing the regenerative capacity of neonatal cardiomyocytes has tricular expression of genes and the properties of the extracellular matrix certainly been explored, but studies such as these provide a clear persist [193–195]. mechanistic view of a role for DG in limiting overproliferation of car- diomyocytes at sites of injury. 2.2.5. Arrhythmogenesis Arrhythmias are a common finding in muscular dystrophies. In pa- 2.2.4. Unloading of the heart - left ventricular assist device tients with DMD cardiomyopathy, arrhythmias can occur that originate Dystrophin levels at the sarcolemma are altered after patients are from the atrium, such as atrial fibrillation (AF) and flutter [98]. In DMD placed on left ventricular assist device (LVAD) support. These findings patients, abnormalities in atrioventricular conduction have been found suggest, that alterations in dystrophin localization at the cell membrane and cause both short and prolonged PR intervals. Ventricular arrhyth- is a highly tunable adaptation that occurs in the face of changing cardiac mias are detected in 30% DMD patients as premature ventricular beats load [185]. Vatta et al. [34] postulated that a final common pathway upon monitoring, while complex ventricular arrhythmias have been re- underlying contractile dysfunction and dilation in DCM involves changes ported most frequently in patients with severe skeletal muscle disease in cytoskeletal and sarcolemmal proteins. Another study profiled changes [97,196]. Electrocardiographic (ECG) abnormalities in DMD patients in gene expression in a subset of patients on LVAD support that exhibited typically include deep Q-waves, diminishment of S:R ratios, existence of sufficient clinical recovery to allow removal of the device [186]. LV polyphasic R-waves and increased frequency of premature ventricular myocardial samples were collected during LVAD implantation and contractions. In an earlier study, the ECG abnormalities of the mdx mice explantation (removal/transplantation) and Affymetrix microarray were improved by the transgenic overexpression of nitric oxide in the analysis was used to examine changes in gene expression of sarcomeric myocardium [197]. In addition, the elevated expression of nNOS by the and nonsarcomeric cytoskeletal proteins. In this study, changes of transgene prevented progressive development of ventricular fibrosis. expression were found in a number of proteins that associate with dys- As mentioned earlier, the primary defect in most muscular dystro- trophin and also in β-integrin signaling networks [186]. In patients who phies is a loss of sarcolemmal integrity and the onset of secondary mo- did not recover cardiac function after LVAD support it was found that lecular mechanisms e.g. elevated or dysregulated cytosolic calcium that dystrophin-like proteins increased including dystroglycan, syntrophin-α precipitate myocyte degeneration and necrosis. The calcium hypothesis and syntrophin-β. Whereas, in the recovered group β-SG increased while of muscular dystrophies, has been put to the test in genetically modified dystrophin and syntrophin decreased. The sarcomeric proteins found mouse models and overall, recent data has largely supported this concept increased in the recovered group included βactin, α-tropomyosin, [198]. The DGC has a role in maintaining the normal cellular calcium α1-actinin and α-filamin A, whereas at explantation, proteins that were gradient through regulation of several membrane proteins and also in- decreased included troponin T3 and α2-actinin. Vinculin and syntrophins fluences sarcolemmal organization. Dysregulation of these proteins’ decreased in the recovered group as well [186,187]. See Fig. 3C for more function allows abnormal stress-induced calcium entry into car- detailed explanations of sarcolemmal and sarcomeric alterations in diomyocytes altering calcium homeostasis ultimately affecting the gen- recovered patient’s hearts after implantation. These findings should be eration of action potentials (AP). The lack of dystrophin appears explored further to determine whether changes in these proteins drive responsible for improper activation of stretch-activated channels (SACs) recovery of cardiac function or are remodeled as a secondary response to [199], which include the large family of transient receptor potential improved heart function. In addition, cardiomyopathy patients with (TRP) channels [200]. A mouse model was developed where the mdx heart failure have alterations in dystrophin and dystrophin-associated mice overexpressed transient receptor potential vanilloid type 2 (TRPV2) protein complexes. Overall, these findings suggest that the link be- channels two-fold. In the mdx mice, the TRPV2 normally exhibits an tween the sarcomere to the sarcolemma and extracellular matrix must be intracellular localization, but when overexpressed in the mdx mice, the strictly preserved to prevent mechanical injury and maintain normal TRPV2 channels translocate back to the sarcolemma and are prominently left-ventricular size and function [34]. distributed along the T-tubules. Pharmacological and physical blockage A large proportion of patients with end-stage cardiomyopathy of by pore-blocking antibodies and small-interfering RNA (siRNA)-me- either dilated or ischemic origins exhibited a disruption of the dystrophin diated ablation of the protein suggest that TRPV2 is involved in the amino-terminus, although other dystrophin domains were retained. In a defective cellular calcium handling in dystrophic cardiomyocytes [120]. subset of patients, disruption of the dystrophin amino-terminus was Another study utilizing whole cell patch-clamp, demonstrated that reversible after introduction of LVAD support [34]. In a follow up study, dystrophic calcium channel abnormalities contribute to the ECG of disruption of the N-terminal dystrophin was evident in DCM and dystrophic mice [201]. Further findings conclude that a gain of function ischemic failing hearts obtained from DCM or ischemic cardiomyopathy of L-type calcium channels (LTCC) may be responsible for disturbing patients, which was reverse remodeled in both ventricles in most patients electrophysiology in dystrophic mice leading to arrhythmias [201]. after unloading by LVAD support [188]. A recent study has shown the Elevation of resting calcium levels in the heart has been associated efficacy of LVAD support as a destination therapy for palliative treatment with increased CICR events and calcium leak from the sarcoplasmic re- of patients with cardiac end-stage dystrophinopathies [189]. The median ticulum during diastole [202,203]. The ryanodine receptor type 2 (RyR2) age of patients was 16.5 years old with variable outcomes post LVAD and intracellular calcium release channels on the SR membrane regulate implantation. This approach may be able to extend the quality and release of calcium during excitation-contraction coupling. Elevated dia- duration of life in these patients beyond what current respiratory ther- stolic calcium levels and oxidative stress in the mdx mice may activate or apies provide. The benefit of long-term unloading by LVAD therapy and potentiate the activation of calcium/calmodulin-dependent protein ki- the rate of effective LVAD explantation has been evaluated [190,191]. A nase II (CaMKII), which phosphorylates RyR2 [121,200]. Hyper- number of studies have examined large data sets to identify a patient phosphorylation of RyR2 by CaMKII promotes diastolic calcium leak and profile (young age, nonischemic HF, no implantable defibrillator, short induction of ventricular tachycardia (VT) in mice with heart failure

61 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 induced by pressure overload [204]. A study from the same group found 2.2.6. Acquired cardiomyopathies that enhanced RyR2 phosphorylation by CaMKII increases SR calcium leak and induced VT in the mdx mice [205]. Treatment of these mice with 2.2.6.1. Cardiotoxicity. Anthracycline-based therapies are commonly a CaMKII inhibitor or mutation of a CaMKII phosphorylation site on RyR2 prescribed to cancer patients. Doxorubicin remains one the most effective suppressed spontaneous arrhythmogenic calcium waves [205]. cancer drugs that has been developed to date, however it causes car- Studies in human DMD hearts suggest that dystrophin loss affects the diomyopathy that is typically refractory to common treatment regimens proper protein levels and localization of the gap junction protein con- [219]. Doxorubicin toxicity can be acute and occur within 2–3 days of the nexin43 (Cx43). Alterations in Cx43 distribution in cardiomyocytes first anti-cancer treatment leading to the development of DCM. Proposed cause arrhythmogenesis and may be an underlying cause of sudden death causes of doxorubicin toxicity are increased oxidative stress, which is [206]. In DMD mouse models and in human DMD tissues, Cx43 protein evidenced by increased levels of reactive oxygen species (ROS) and lipid levels have been shown to be substantially higher and pathologically peroxidation [220,221]. Furthermore, doxorubicin induces toxic damage localized to lateral sides of cardiomyocytes. Inhibition of Cx43 activity by to mitochondria in the heart leading to ROS and intracellular hydrogen Cx43 peptide mimetics prevented DMD mice from developing severe peroxide formation [222]. Several studies have suggested that doxoru- arrhythmias upon isoproterenol challenge [207]. Subsequently, the same bicin induces cardiomyocyte apoptosis [223,224]. Additional mecha- group demonstrated that hypo-phosphorylation of the Cx43 serine-triplet nisms of cardiotoxicity include the downregulation of key cytoskeletal, þ (S3E) triggers the pathological redistribution of Cx43 to the lateral sides sarcomeric and Ca2 handling genes including: α-actin, desmin, troponin of DMD cardiomyocytes and protects the mdxS3E mice from inducible I, myosin light chain, myosin heavy chain and SERCA2a, associated with ε arrhythmias [208]. Post-translational addition of N -lysine acetylation reduced myocardial contractile and diastolic function [225,226]. See has been found to be important in maintaining Cx43 localization to Fig. 4A for a summary of the mechanisms that promote cardiotoxicity in intercalated discs in the dystrophic hearts leading to altered cardiac cardiomyocytes as well as alterations in the DGC. During cardiotoxic rhythm [118]. Hence, arrhythmogenesis associated with dystrophin loss injury, the abundance of DGC proteins at the sarcolemma is substantially includes lateralization of Cx43 from gap junctions to Cx43 hemichannels affected and may be a contributing factor in the functional decline of the increasing susceptibility to isoproterenol-induced arrhythmias (Fig. 3D). heart. The use of anthracyclines such as doxorubicin in the clinic en- Dystrophin contains two F-actin binding domains that assist in counters limitations due to dosage-dependent cardiotoxicity that can maintaining its connection to the actin network [209]. Syntrophins are cause development of cardiomyopathy. While many aspects of this dis- adapter proteins associated with dystrophin important in localizing order remain poorly understood, genes in the heart encoding cytoskeletal signaling proteins, kinases, water and ion channels and nitric oxide or sarcolemmal proteins appear changed by doxorubicin treatment. synthase to specific intracellular locations. The cellular localization of Furthermore, it has been shown that a single therapeutic dose of doxo- syntrophins is regulated through reorganization of the cytoskeleton rubicin causes remodeling of cytoskeletal and ECM proteins [227]. The [210]. During heart failure scaffolding proteins modulate cardiac cardiotoxic effects of doxorubicin are more pronounced in the remodeling including Cav-3 and α1-syntrophin which localize to the dystrophin-deficient mdx mice and the underlying pathological mecha- þ þ T-tubule and remain bound to the DGC. Cav-3 binds to the Na /Ca nisms may be exacerbated by known alterations in cellular adhesion, exchanger [211], L-type calcium channels [212], nNOS [213] and the cytoskeleton and inflammatory and immune responsiveness. A study by DGC [214,215]. Whereas, α1-syntrophin binds to Nav1.5, nNOS and Deng et al. [228] highlights the fact that individuals may face differing F-actin and has diverse roles in maintaining structure, electrical con- susceptibilities to doxorubicin cardiotoxicity and that cardiotoxic drugs duction and signal transduction in the failing heart [212]. Mutations in may accelerate the development of pre-clinical cardiomyopathies that proteins that comprise the cytoskeleton and scaffolding function of the are caused by altered sarcolemma or cytoskeletal proteins. DGC may lead to progressive dysfunction and potential alterations in Studies have been conducted to test whether the loss/reduction of localization and expression of ion channels thus rendering the myocar- dystrophin from the sarcolemma underlies heart failure associated with dium more susceptible to developing ventricular arrhythmias [210]. doxorubicin-induced cardiomyopathy. A study in rats utilized cumulative Although myocardial dystrophin has been shown to remodel in both doses of doxorubicin during a two-week period that led to ventricular the right and left ventricles in patients with end stage heart failure [34, dysfunction and a marked loss of dystrophin from cardiomyocyte cell 188], there is an apparent connection between differential dystrophin membranes [23]. It was discovered that doxorubicin-treated cardiac expression in the atria and susceptibility to AF. In the first report of myofibers had increased sarcolemmal permeability and sarcomeric pro- dystrophin remodeling in the atria, it was found by immunohistochem- tein disruption. These pathologic changes may be due to oxidative ical analysis that patients with severe right atrial dilation and atrial damage and/or functional impairment of the DGC. Administration of flutter had reduced dystrophin staining in the right atria [216]. It has dantrolene, similar to septic cardiomyopathy, improved survival rate of been demonstrated that atrial-specific upregulation of miR-31 occurs in doxorubicin-treated rats and preserved myocardial dystrophin. The human AF leading to dystrophin and subsequently nNOS depletion. It is beneficial outcomes of dantrolene are most likely due to inhibitory ef- expected that these alterations contribute to the electrical phenotype and fects on calpains that are significantly increased in the damaged induce arrhythmia in AF. Measures that prevent miR-31 binding to the myocardium [23]. The studies in dystrophin-deficient mice indicate dystrophin gene DYS 3’ UTR enhanced expression of dystrophin protein increased susceptibility to cardiac injury resulting from anthracycline without affecting mRNA, consistent with a role in repressing translation. treatment and provide insight that alterations in dystrophin may be a Not unexpectedly, increased dystrophin protein also caused a corre- final common pathway for development of cardiomyopathy [229]. sponding increase in nNOS protein levels since dystrophin has a role in stabilizing the cellular location of nNOS in the cell [217]. In addition, 2.2.6.2. Sepsis. Sepsis is characterized as dysregulated host response to since the DGC makes prominent connections with the cytoskeleton, rare infection that leads to life-threatening organ dysfunction due to systemic loss-of-function mutations in DCM-associated cytoskeletal genes may inflammatory response syndrome (SIRS) and normally occurs in response play a role in early-onset AF, through its influence on the development of to systemic bacterial infection [230]. The heart is among the organs atrial cardiomyopathy [218]. It is expected therefore that a large protein affected by sepsis. The pathophysiology of myocardial dysfunction in such as dystrophin provides many points of contact with the cytoskeleton sepsis is predominately functional rather than anatomically based [231]. and facilitates the correct localization of ion channels involved in con- Initially an overactivation of the innate immune system, it leads to a duction of electrical signals in the myocardium. Therefore, strategies that hyperinflammatory stage and other early effects including massive can successfully replenish or replace dystrophin at the cell membrane release of catecholamines from the autonomic nervous system and after acute injury could protect from life-threatening arrhythmias. persistent stimulation of α- and β-adrenergic receptors. In severe

62 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71

Fig. 4. Impact of Acquired Cardiomyopathies on Proteins of the DGC. (A) After anthracycline treatment such as doxorubicin, cardiomyopathy may develop due to multiple mechanisms. The mitochondria become damaged - signified by the lightening symbol, and release hydrogen peroxide (H2O2), which ultimately induces apoptotic pathways and cardiomyocyte death. Changes in transcriptional regulation in the nucleus cause downregulation of specific proteins of the sarcomere (structure and zones pictured) - shown in red print, causing a reduction in contractility. Other alterations include a reduction in sarcoplasmic reticulum ATPase þ þ (SERCA2a) levels. The Na /Ca2 exchanger allows greater calcium entry leading to activation of calpains. Calpain activation - indicated by scissors, causes disruption of dystrophin at the sarcolemma. Ryanodine receptor (RyR) and dihydropyridine receptor (DHPR) are shown to be responsible for SR calcium release. (B) In septic hearts, a loss or reduction in dystrophin (light purple and fragmented), β-dystroglycan (loss indicated by increased transparency) and F-actin may disrupt the me- chanical linkage connecting intracellular actin to dystrophin, through the dystroglycans to the extracellular matrix. Such alterations may disrupt force transmission in septic cardiomyopathy. Actin is shown to be fragmented, and the increased transparency of β-dystroglycan and dystrophin indicate their lower expression at the sarcolemma in septic cardiomyopathy. (C) Infection with Coxsackie virus (Viral infection panel) causes the link between dystrophin and intracellular actin to be severed. This is due to the action of Protease 2a, a virally encoded protease, that cleaves dystrophin and leaves C-term dystrophin at the sarcolemma. Loss of normal dystrophin (Dystrophin deficiency panel) is caused by variable insults, including genetic and/or other causes. It has been suggested, that Coxsackie virus infection affects the myocardium in a two-hit fashion by first cleaving dystrophin and then preventing localization of utrophin to the compromised DGC, since C-term dys- trophin remains bound, preventing compensation by utrophin. The two-hit model was proposed in Barnabei et al. [257]. (D) Chagas disease is the result of infection with Trypanosoma cruzi, a protozoan. Cardiac manifestations are due to inflammatory activation and detection of intracellular parasites in the heart tissue and include DCM, arrhythmias, cardioembolism, stroke and congestive heart failure. Dystrophin is cleaved by increased calpain activity and may be completely lost from the sarcolemma. Dantrolene, which inhibits release of calcium from the sarcoplasmic reticulum by the ryanodine receptor 2 (RyR2) has been shown to restore dystrophin and reduce calpain levels. Figure created using BioRender.com. sepsis/shock, the predominant cause of death is myocardial depression and puncture (CLP) [235]. Cardiac output and efficiency were signifi- that is associated with degenerative structural changes in the heart. cantly higher in treated versus untreated rats and was attributed to Septic cardiomyopathy is potentially reversible and involves both the left improved utilization of oxygen by the myocardium. and right ventricles unlike traditional cardiomyopathies [231]. A study by Celes et al. [236] demonstrated that CLP injury in mice The cardiomyocyte cytoskeleton provides a stabilizing role and me- caused severe sepsis and led to a 50% reduction of sarcolemmal dystro- chanical transduction is highly dependent on the support of membrane- phin and β-DG compared to sham-controls. See Fig. 4B for schematic of associated proteins such as the DGC that connect the basal lamina - with documented changes in the DGC and F-actin in the heart under septic intracellular actin [232]. The DGC is concentrated at costamere struc- conditions. Levels of laminin-α2 however remained the same. Interest- tures and therefore situated along the vertical axis of force transmission ingly, the treatment of CLP injured mice with the antioxidant superoxide between the sarcomeric contractile apparatus and the sarcolemma that dismutase (SOD) was protective. The authors suggested that connects to the extracellular matrix [233,234]. Use of β-blockade has sepsis-induced myocardial dysfunction may cause oxidative damage that been shown effective in patients suffering from myocardial injury. One may lead to the loss of these two proteins, sarcolemmal destabilization study demonstrated the protective effects of esmolol, a selective β1-se- and myofilament degeneration or myocytolysis [236]. Further studies lective blocker on myocardial function in septic rats after cecal ligation examined the pathogenesis of septic cardiomyopathy, and demonstrated

63 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 that exposure of cultured neonatal cardiomyocytes to serum obtained contraction coupling [254]. A study by Andreoletti et al. [255] assessed 2þ from mice with severe sepsis had greatly increased calpain-1 and [Ca ]i whether active enterovirus infection of cardiac tissue plays a direct role levels. The septic serum treated cardiomyocytes were found to have in the pathological presentation of myocardial infarction (MI). Endo- decreased dystrophin expression, F-actin filament disruption and cyto- myocardial samples obtained from patients who died suddenly of AMI plasmic blebbing. Also, hearts from mice with severe sepsis had were evaluated and compared to matched controls. Markers of entero- depressed contractile function and very low rates of survival that was virus infection were found by reverse transcriptase-PCR in 40% of pa- þ greatly improved by the Ca2 channel blocker verapamil and the cardiac tients who suddenly succumbed to MI, 4% of matched patients without RyR2 blocker dantrolene. Verapamil treatment preserved dystrophin, cardiac disease and 4% of patients with non-coronary chronic cardio- actin and myosin levels in the cardiomyocytes and prevented the increase myopathy. All enterovirus RNA-positive patients exhibited capsid viral of calpain-1. Ongoing studies have utilized immunofluorescence to protein 1 (VP1) expression, providing evidence of viral protein synthesis. examine changes in SG localization in sepsis as it assumes an intracellular Furthermore, CVB infected tissue regions corresponded with areas of distribution. The authors of the study by Ventura Spagnolo et al. [237] disrupted sarcolemmal dystrophin localization [255]. Another study propose that SG expression could serve as a marker of severe cardiac used knockin mice to further pinpoint causes of CVB-associated cardio- septic injury and may be more informative than routine methods using myopathy and found disease abrogation in mice expressing hematoxylin-eosin staining. Overall, in sepsis remodeling of the DGC at cleavage-resistant dystrophin, which had the protease 2A cleavage site the sarcolemma appears to be the result of increased calpain activity, removed [256]. which affects some DGC subunits more than others. It remains to be seen Barnabei et al. conducted a study to define how enterovirus infection however, how much the DGC remodeling in sepsis drives cardiac causes DCM [257]. Since it was known that the virus-encoded 2A pro- dysfunction since other contributing factors exist including massive tease cleaves dystrophin, this study showed that the cleavage product of catecholamine release and inflammation. Viral infection can also cause dystrophin - CtermDys - acts in a dominant negative manner to cause DGC remodeling similar to what occurs in sepsis, however several viruses cardiac fibrosis, increased susceptibility to myocardial ischemic injury, cause distinct changes and are covered in the next section. and heightened incidence of mortality after in vivo cardiac stress testing. Cardiomyopathy caused by CtermDys was found to be more severe than 2.2.6.3. Viral infection. Enteroviral infection by mainly coxsackie B vi- that caused by dystrophin deficiency. To exert a dominant-negative ruses (CVB), a non-enveloped virus in the picornavirus family, can cause peptide effect, CtermDys must be localized to the sarcolemma and dys- an acquired form of DCM [238] and ischemic heart disease [239]. Studies trophin levels at <50% of the normal amount. To explain these effects, in cultured myocytes infected with CVB showed direct cleavage of dys- the authors proposed that CtermDys causes cardiomyopathy in a two-hit trophin by the enteroviral-encoded protease 2A. In vivo studies by the dominant-negative fashion, whereby CtermDys at the membrane severs same group showed morphological disruption of dystrophin and the DGC the normal link to cortical actin and inhibits both full-length dystrophin proteins α-SG and β-DG [16]. Therefore, it was directly demonstrated and utrophin, its compensatory autosomal homologue from binding to that Coxsackievirus B3 (CVB3) can be the source of myocardial infection the cardiac cell membrane [257]. A schematic is shown in Fig. 4C that and myocarditis. In the majority (90%) of affected patients the symptoms outlines the proposed two-hit fashion by which dystrophin cleavage in are mild and complete convalescence may be attained. However, patients CVB3 infected hearts leads to viral myocarditis. Enterovirus-2C is a viral who exhibit acute fulminant myocarditis have excellent long-term RNA helicase that inhibits synthesis of proteins by the host. To counter prognosis if they survive the initial acute illness, whereas patients that dystrophin cleavage, a chemically modified enterovirus-2C inhibitor present with acute non-fulminant myocarditis are half as likely to have (E2CI) was generated. In vivo studies in DBA/2 mice tested the efficacy of long-term survival [240]. A subset of patients however, rapidly develop E2CI. The mice were first infected with CVB3 and then received an IP severe cardiac dysfunction, ventricular arrhythmias and progress to injection with E2CI. Viral replication was reduced in the DBA/2 mice sudden cardiac death (SCD) [241]. Enteroviruses are not the only viruses compared to controls along with diminished chronic myocardial damage that cause myocarditis although the mechanisms underlying their and reduced mortality [258]. Recent events reporting clinical presenta- disruption of cardiac function are the most well characterized. Over the tion of the novel coronavirus SARS-CoV-2 infection suggest that it may be last several decades, the evolution of viral causes of myocarditis has a cause of fulminant myocarditis, especially in light of substantial ele- shifted and now more clinical cases have been encountered that are vations of cardiac troponin I (cTnI) levels and recorded arrhythmia that caused by non-enteroviral sources including other cardiotropic viruses hint at cardiac injury [259–261]. Additional longstanding investigation such as parvovirus B19 (PVB19) [242,243], human herpes virus 6 is needed to fully understand whether SARS-CoV-2 causes myocarditis (HHV6) [244], hepatitis C (HCV) [245], Epstein-Barr virus (EBV) [246, and alterations of the DGC. 247] and coronaviruses [248]. The mechanisms underlying myocarditis due to non-enteroviruses are not as well-defined. Beyond a direct role in 2.2.6.4. Parasitic infection. Infection with the protozoan parasite Trypa- myocarditis, DG has an important role in assembly of the basement nosoma cruzi (T. cruzi) causes Chagas disease, which is endemic in Latin membrane [249] and muscle regeneration [250]. Interestingly, α-DG America and an important cause of cardiac disease including DCM, ar- facilitates viral infection by serving as a receptor for lymphocytic cho- rhythmias, cardioembolism, stroke and congestive heart failure [262]. riomeningitis virus and Lassa fever virus [251]. The function of α-DG as Chagas cardiomyopathy is the most frequent severe manifestation, an extracellular matrix receptor is lost when the N-terminus is absent and though it may take a long time to manifest after initial infection by its interaction with LARGE1 is abrogated [252]. When mice expressing T. cruzi. Chagas heart disease exists as two phases - acute and chronic, α-DG minus N-term are infected with Influenza A they exhibit higher and the occurrence of the phases can span many years. Parasite persis- viral titers than wild type mice, suggesting that the α-DG N-terminus has tence is fundamental to the development and progression of Chagas an important role in controlling viral load [253]. cardiomyopathy, therefore effective antiparasitic treatment in the A number of studies have investigated the underlying causes of chronic phase could prevent disease complications [263]. A study by myocarditis due to enterovirus CVB3. In endomyocardial biopsied tissues Prado et al. [18] found that similar to the muscular dystrophy-associated from patients with CVB-linked myocarditis, cardiomyocytes display a cardiomyopathies, dystrophin expression levels are decreased in mice focal loss of sarcolemmal staining of dystrophin and β-SG. The signifi- early in the disease process. The alteration of dystrophin expression cance and direct connection between CVB and development of DCM was preceded the later development of cardiomyopathy. In mice 30 days-post established by generating cardiac-specific transgenic mice that expressed infection, intracellular parasites were detectable in the myocardium a replication-restricted full-length CVB3 DNA. These mice developed causing focal or complete dystrophin loss by 100 days post infection, myocardial interstitial fibrosis and DCM with abnormalities in excitation- although at that point parasites were no longer detectable [19]. In a

64 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71

þ follow up study, dantrolene, a drug which inhibits Ca2 release from the 2.2.7.4. Hereditary cardiomyopathies. In the case of hereditary cardio- SR by RyR, was administered to T. cruzi infected mice, which restored myopathies arising from pathologic mutations in the proteins of the DGC, dystrophin and calpain levels similar to controls [264]. Outcomes of this the goal of therapy has been to use vector delivery options such as study are highlighted in the schematic in Fig. 4D. In recent decades, the adenovirus-associated vectors (AAV) to replace the defective subunit. In concern of infection with T. cruzi has been increasing in non-endemic dystrophinopathies, this has remained a fundamental challenge, since regions including the United States and Europe [265,266]. Heart com- dystrophin is such a large protein. Multiple options have been explored plications due to Chagas disease have been reported in Latin immigrants including utrophin upregulation, correction of dystrophin mutations to the United States and in Japan - immigrants from Brazil of Japanese using exon-skipping, CRISPR-Cas9 editing, stop codon readthrough, and origins [265]. In summary, T. cruzi infection is a cause of serious cardiac replacement of dystrophin by delivery of mini-dystrophins [279,280]. disease marked by a precipitous decline in cardiac function attributed to The question remains however about how much restoration of dystro- dystrophin loss that may not be diagnosed early enough and can result in phin expression is sufficient [280]. Pathogenesis of limb girdle muscular adverse outcomes. dystrophies can be relieved by rescuing the missing DGC component in the heart [281] and/or smooth muscle [156,160,282]. Since DGC 2.2.7. Implications for therapy remodeling plays such an integral role in a large number of seemingly unrelated cardiac disease conditions, strategies should be revisited that 2.2.7.1. Current pharmaceutical-based heart failure treatments. The treat- restore lost DGC expression in the heart. This topic should be ment strategies for heart failure depend on the symptoms that patients re-examined in view of our advanced knowledge concerning gene de- present. Drugs are prescribed based upon the cardiovascular symptom livery strategies, microtubule lattice, cell membrane protein dynamics that is contributing to heart failure. Major classes of drugs that are pre- and regeneration. In lieu of effective replacement of the defective DGC scribed include: 1) anti-hypertensive therapies that lower blood pressure protein, alternative strategies have been developed that stabilize the by reducing cardiac afterload, 2) therapies that boost cardiac contrac- complex and cardiac sarcolemma [71,283–289]. tility by improving pump function, 3) diuretics that diminish blood volume and work on the heart. These drug regimens are designed to 2.2.7.5. The DGC as a therapeutic target. Data presented is this review prolong life and reduce symptoms of heart failure and improve cardiac suggests, that remodeling of the DGC has a significant impact on striated function. In dystrophic patients, the pre-symptomatic treatment of car- muscle function. In fact, the etiology of DGC dysfunction/disassembly diovascular disease includes standard therapeutics, i.e. inhibitors of has been clearly shown to result from genetic causes as well as from a angiotensin-converting enzyme, angiotensin-receptor blockers or corti- number of pathological conditions. With such wide-ranging impacts on coid receptor antagonists, which improve outcomes without specifically the cardiovascular, musculoskeletal and nervous system, it is relevant to targeting the underlying mechanisms leading to disease [267]. consider the DGC as a potential target of therapeutic interventions beyond the correction of muscular dystrophies. In fact, it is quite striking 2.2.7.2. Cardiac unloading. Despite the many advances in the cardiac that the same protein complex is so integral to a broad spectrum of dis- field that prolong life, effective reversal of heart failure has remained an eases that affect cardiac function including IRI, sepsis, cardiotoxicity and elusive goal. LVAD implantation is expensive and commonly used as a infection, as well as, interventions that aid in protecting the diseased bridge-to-transplant while the impact of cardiac unloading on improving heart, including LVAD-support and cardio-regeneration. Treatments cardiac performance has shown variable success. LVAD and heart using membrane sealants, such as Poloxamer P188 that target car- transplant related hospitalizations remain costly and post-discharge diomyocyte membrane instability, have been shown to prevent devel- mortality is high. Multiple strategies have been investigated, including opment of dystrophic cardiomyopathy [283,290,291] and protect cell-transplantation-based treatments, to replace damaged car- against ischemia-reperfusion injury in a number of models [284,292, diomyocytes in failing hearts. Understanding the cases where remodeling 293]. In the case of dystrophin loss due to non-polio enterovirus infec- of the DGC due to unloading improves cardiac function will provide tion, acute heart failure can cause sudden mortality. No effective anti- insight on whether intervention at earlier time points may increase virals are currently available, however, recently, the synthesized success if treatment is initiated prior to the point of irreversible decline. antiviral 6aw shows potent broad-spectrum antiviral activity against non-polio enteroviruses and good stability in mouse microsomes [294]. 2.2.7.3. Regenerative strategies. Based upon the current need to design The studies discussed in the present review, can provide a basis for therapeutic options for treatment of heart failure and related comor- understanding the common mechanisms leading to dystrophin and DGC bidities more information needs to be gathered to understand the mo- loss from the sarcolemma as well as the role that the DGC plays as a lecular aspects regulating stability of the cardiomyocyte sarcolemma and signaling scaffold to direct essential functions for cardiomyocyte main- cytoskeleton. The acquisition of new knowledge will allow development tenance. Early studies have examined the deleterious effects of ischemia of innovative therapeutic strategies that stimulate cardiogenesis or in the heart and proposed protective strategies pre- and post-ischemic safeguard existing cardiomyocytes to protect against myocardial infarc- events aimed at maintaining dystrophin at the sarcolemma. In terms of tion and/or heart failure [273]. Much effort has been put forward toward acute events, such as myocardial infarction, challenges remain in main- regenerative therapies for improving myocardial function, including taining the structurally important DGC at the sarcolemma and preventing stem cell therapies, however, none have provided significant regenera- internalization of DGC proteins during myocardial stunning or calpain tion [274]. Numerous replacement cell sources have been examined cleavage. Increased expression of proteins that augment dystrophin including embryonic stem cells, cardiac progenitor cells and other non- expression [71] or that maintain the integrity of the DGC in car- cardiomyocyte cell types [268–271] may deliver needed cellular rein- diomyocytes exposed to hypoxia/reoxygenation conditions has been forcement to the myocardium. Tissue engineering and genetic shown to lessen the severity of myocardial infarction injury [289]. While modification approaches provide a complementary technique to cell these strategies may improve cardiomyocyte integrity and heart function, transplant methods [272]. Ongoing efforts include development of the immediate repercussions of cardiac injury must also be addressed, 2þ matured engineered human myocardium as a treatment strategy to repair including unregulated Ca entry, calpain activation, dystrophin cleav- failing hearts [275]. Successful treatment of guinea pigs with engineered age and mislocalization as well as inflammation. heart tissue derived from pluripotent stem cells has been reported [276]. 2.2.7.4.1. Engineered tissue strategies or enhanced delivery Other regenerative approaches have been directed at regulating cell cycle options. Since a number of disease conditions lead to development of to stimulate proliferation in adult cardiomyocytes [277] or used recon- cardiomyopathy or heart failure as a result of dystrophin loss in discrete stitution strategies to regenerate adult mammalian hearts [278]. portions of the heart, delivery of mini-dystrophins or proteins that

65 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71 stabilize the DGC to areas of cardiac injury could potentially halt the Declaration of competing interest deleterious downstream events that cause heart failure. Delivery methods to introduce DGC proteins or genes or therapeutic strategies that The authors declare no conflict of interests. increase its expression have been greatly improved and centered on correcting genetic diseases such as DMD. In addition, recent technolog- References ical advancements may provide better methods to repair damaged areas of the heart. Injectable hydrogels and cardiac patches are the most [1] Porter GA, Dmytrenko GM, Winkelmann JC, Bloch RJ. Dystrophin colocalizes with beta-spectrin in distinct subsarcolemmal domains in mammalian skeletal commonly employed approaches for localized cardiac delivery of cells muscle. J Cell Biol 1992;117(5):997–1005. overexpressing a missing DGC component, i.e. mini-dystrophin and/or [2] Hoffman EP, Brown Jr RH, Kunkel LM. Dystrophin: the protein product of the other therapeutics shown to increase DGC expression. Both hydrogels Duchenne muscular dystrophy locus. Cell 1987;51(6):919–28. [3] Muntoni F, Torelli S, Ferlini A. Dystrophin and mutations: one gene, several and cardiac patches can be further combined with polymeric, lipid-based proteins, multiple phenotypes. Lancet Neurol 2003;2(12):731–40. or inorganic nanocarriers designed to enable delivery of bioactive pro- [4] Crosbie RH, Yamada H, Venzke DP, Lisanti MP, Campbell KP. Caveolin-3 is not an teins, peptides, nucleic acids or drugs to or near the area of injury integral component of the dystrophin glycoprotein complex. FEBS Lett 1998; – (reviewed in Ref. [295]). Intended to be administered to the heart in a 427(2):279 82. [5] Venema VJ, Ju H, Zou R, Venema RC. Interaction of neuronal nitric-oxide minimally invasive fashion via intravenous, intracoronary, or intra- synthase with caveolin-3 in skeletal muscle. Identification of a novel caveolin myocardial routes, injectable hydrogels composed of naturally derived or scaffolding/inhibitory domain. J Biol Chem 1997;272(45):28187–90. synthetic polymers are typically designed to undergo a stimuli-triggered [6] Perronnet C, Vaillend C. Dystrophins, utrophins, and associated scaffolding complexes: role in mammalian brain and implications for therapeutic strategies. sol-gel transition upon implantation. J Biomed Biotechnol 2010;2010:849426. By contract, cardiac patches consisting of electrospun polymeric [7] Tinsley JM, Davies KE. Utrophin: a potential replacement for dystrophin? – – membranes, hydrogels or decellularized extracellular matrix (ECM) Neuromuscul Disord 1993;3(5 6):537 9. [8] Lapidos KA, Kakkar R, McNally EM. The dystrophin glycoprotein complex: scaffolds are directly transplanted onto the epicardial surface and are signaling strength and integrity for the sarcolemma. Circ Res 2004;94(8): generally used to cover larger tissue areas and provide some mechanical 1023–31. support [296]. Various cardiac patches [297–300] and injectable [9] McNally E, Allikian M, Wheeler MT, Mislow JM, Heydemann A. Cytoskeletal – – defects in cardiomyopathy. J Mol Cell Cardiol 2003;35(3):231 41. hydrogel systems [301 304] have been shown to successfully localize [10] Han F, Lu YM, Hasegawa H, Kanai H, Hachimura E, Shirasaki Y, et al. Inhibition of delivery of peptides, proteins and nucleic acids in preclinical MI models, dystrophin breakdown and endothelial nitric-oxide synthase uncoupling accounts as well as enhance transplanted cell engraftment. Such strategies could for cytoprotection by 3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6- dimethoxy-1-(4-imidazo lylmethyl)-1H-indazole dihydrochloride 3.5 hydrate (DY- thus be adapted to localize cardiac delivery of DGC proteins or proteins 9760e) in left ventricular hypertrophied Mice. J Pharmacol Exp Therapeut 2010; that stabilize the DGC, nucleic acids that encode such proteins, or cells 332(2):421–8. engineered to overexpress these proteins. [11] Khairallah M, Khairallah R, Young ME, Dyck JR, Petrof BJ, Rosiers C Des. Metabolic and signaling alterations in dystrophin-deficient hearts precede overt cardiomyopathy. J Mol Cell Cardiol 2007;43(2):119–29. 3. Conclusions [12] Takahashi M, Tanonaka K, Yoshida H, Koshimizu M, Oikawa R, Daicho T, et al. Effects of angiotensin I-converting enzyme inhibitor and angiotensin II type 1 Overall, in the cardiac pathologies associated with the DGC, cleavage receptor blocker on the right ventricular sarcoglycans and dystrophin after left coronary artery ligation. Eur J Pharmacol 2005;522(1–3):84–93. of dystrophin has been detected in human hearts of DCM patients of [13] Takahashi M, Tanonaka K, Yoshida H, Oikawa R, Koshimizu M, Daicho T, et al. unknown etiologies. These alterations in dystrophin localization and Effects of ACE inhibitor and AT1 blocker on dystrophin-related proteins and – sarcolemma stability have far reaching consequences for associated calpain in failing heart. Cardiovasc Res 2005;65(2):356 65. [14] Schroen B, Heymans S, Sharma U, Blankesteijn WM, Pokharel S, Cleutjens JP, proteins outside the DGC as well as the cytoskeletal architecture. This et al. Thrombospondin-2 is essential for myocardial matrix integrity: increased supports the overarching role of dystrophin cleavage and translocation to expression identifies failure-prone cardiac hypertrophy. Circ Res 2004;95(5): the myoplasm as a primary source of sarcolemmal instability, irrespective 515–22. [15] Ervasti JM, Campbell KP. A role for the dystrophin-glycoprotein complex as a of disease course and origin. Designing therapeutic strategies aimed at transmembrane linker between laminin and actin. J Cell Biol 1993;122(4): mitigating these changes may be beneficial to a whole spectrum of dis- 809–23. eases with cardiac dysfunction arising from DGC and dystrophin [16] Badorff C, Lee GH, Lamphear BJ, Martone ME, Campbell KP, Rhoads RE, et al. Enteroviral protease 2A cleaves dystrophin: evidence of cytoskeletal disruption in remodeling. an acquired cardiomyopathy. Nat Med 1999;5(3):320–6. [17] Yoshida H, Takahashi M, Koshimizu M, Tanonaka K, Oikawa R, Toyo-oka T, et al. Financial disclosure Decrease in sarcoglycans and dystrophin in failing heart following acute myocardial infarction. Cardiovasc Res 2003;59(2):419–27. [18] Celes MR, Torres-Duenas D, Malvestio LM, Blefari V, Campos EC, Ramos SG, et al. Michelle S. Parvatiyar has received funding from the following Disruption of sarcolemmal dystrophin and beta-dystroglycan may be a potential sources: the American Heart Association 16SDG29120002, Florida State mechanism for myocardial dysfunction in severe sepsis. Lab Invest 2010;90(4): – University, FSU Council on Research and Creativity funding; and 531 42. [19] Prado CM, Celes MR, Malvestio LM, Campos EC, Silva JS, Jelicks LA, et al. Early Michelle S. Parvatiyar and Isela C. Valera from the Collaborative Colli- dystrophin disruption in the pathogenesis of experimental chronic Chagas sion COVID-19 Seed Fund. cardiomyopathy. Microb Infect 2012;14(1):59–68. [20] Malvestio LM, Celes MR, Milanezi C, Silva JS, Jelicks LA, Tanowitz HB, et al. Role of dystrophin in acute Trypanosoma cruzi infection. Microb Infect 2014;16(9): The author contribution 768–77. [21] Kawada T, Masui F, Tezuka A, Ebisawa T, Kumagai H, Nakazawa M, et al. A novel Study Design: Michelle S. Parvatiyar, Isela C. Valera. scheme of dystrophin disruption for the progression of advanced heart failure. Biochim Biophys Acta 2005;1751(1):73–81. Data Collection: n/a. [22] Campos EC, Romano MM, Prado CM, Rossi MA. Isoproterenol induces primary Statistical Analysis: n/a. loss of dystrophin in rat hearts: correlation with myocardial injury. Int J Exp Data Interpretation: n/a. Pathol 2008;89(5):367–81. [23] Campos EC, O’Connell JL, Malvestio LM, Romano MM, Ramos SG, Celes MR, et al. Manuscript Preparation: Michelle S. Parvatiyar, Isela C. Valera, Calpain-mediated dystrophin disruption may be a potential structural culprit Amanda L. Wacker, Hyun-Seok Hwang, Christina Holmes, Orlando Lai- behind chronic doxorubicin-induced cardiomyopathy. Eur J Pharmacol 2011; tano, Andrew P. Landstrom. 670(2–3):541–53. Literature Search: Michelle S. Parvatiyar, Amanda L. Wacker, Isela C. [24] Muller AL, Dhalla NS. Role of various proteases in cardiac remodeling and progression of heart failure. Heart Fail Rev 2012;17(3):395–409. Valera. [25] Cottin P, Poussard S, Mornet D, Brustis JJ, Mohammadpour M, Leger J, et al. In Funds Collection: n/a. vitro digestion of dystrophin by calcium-dependent proteases, calpains I and II. Biochimie 1992;74(6):565–70.

66 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71

[26] Purintrapiban J, Wang MC, Forsberg NE. Degradation of sarcomeric and [55] Hara Y, Balci-Hayta B, Yoshida-Moriguchi T, Kanagawa M, Beltran-Valero de cytoskeletal proteins in cultured skeletal muscle cells. Comp Biochem Physiol B Bernabe D, Gundesli H, et al. A dystroglycan mutation associated with limb-girdle Biochem Mol Biol 2003;136(3):393–401. muscular dystrophy. N Engl J Med 2011;364(10):939–46. [27] Greyson CR, Schwartz GG, Lu L, Ye S, Helmke S, Xu Y, et al. Calpain inhibition [56] Gee SH, Montanaro F, Lindenbaum MH, Carbonetto S. Dystroglycan-alpha, a attenuates right ventricular contractile dysfunction after acute pressure overload. dystrophin-associated glycoprotein, is a functional agrin receptor. Cell 1994; J Mol Cell Cardiol 2008;44(1):59–68. 77(5):675–86. [28] Towbin JA. The role of cytoskeletal proteins in cardiomyopathies. Curr Opin Cell [57] Talts JF, Andac Z, Gohring W, Brancaccio A, Timpl R. Binding of the G domains of Biol 1998;10(1):131–9. laminin alpha1 and alpha2 chains and perlecan to heparin, sulfatides, alpha- [29] Fabbrizio E, Leger J, Anoal M, Leger JJ, Mornet D. Monoclonal antibodies targeted dystroglycan and several extracellular matrix proteins. EMBO J 1999;18(4): against the C-terminal domain of dystrophin or utrophin. FEBS Lett 1993;322(1): 863–70. 10–4. [58] Ettinger AJ, Feng G, Sanes JR. epsilon-Sarcoglycan, a broadly expressed [30] Prado FP, Dos Santos DO, Blefari V, Silva CA, Machado J, Kettelhut IDC, et al. homologue of the gene mutated in limb-girdle muscular dystrophy 2D. J Biol Early dystrophin loss is coincident with the transition of compensated cardiac Chem 1997;272(51):32534–8. hypertrophy to heart failure. PloS One 2017;12(12):e0189469. [59] McNally EM, Ly CT, Kunkel LM. Human epsilon-sarcoglycan is highly related to [31] Kaprielian RR, Stevenson S, Rothery SM, Cullen MJ, Severs NJ. Distinct patterns of alpha-sarcoglycan (adhalin), the limb girdle muscular dystrophy 2D gene. FEBS dystrophin organization in myocyte sarcolemma and transverse tubules of normal Lett 1998;422(1):27–32. and diseased human myocardium. Circulation 2000;101(22):2586–94. [60] Wheeler MT, Zarnegar S, McNally EM. Zeta-sarcoglycan, a novel component of the [32] Anastasi G, Cutroneo G, Gaeta R, Di Mauro D, Arco A, Consolo A, et al. Dystrophin- sarcoglycan complex, is reduced in muscular dystrophy. Hum Mol Genet 2002; glycoprotein complex and vinculin-talin-integrin system in human adult cardiac 11(18):2147–54. muscle. Int J Mol Med 2009;23(2):149–59. [61] Bonnemann CG, Modi R, Noguchi S, Mizuno Y, Yoshida M, Gussoni E, et al. Beta- [33] Masubuchi N, Shidoh Y, Kondo S, Takatoh J, Hanaoka K. Subcellular localization sarcoglycan (A3b) mutations cause autosomal recessive muscular dystrophy with of dystrophin isoforms in cardiomyocytes and phenotypic analysis of dystrophin- loss of the sarcoglycan complex. Nat Genet 1995;11(3):266–73. deficient mice reveal cardiac myopathy is predominantly caused by a deficiency in [62] Crosbie RH, Lebakken CS, Holt KH, Venzke DP, Straub V, Lee JC, et al. Membrane full-length dystrophin. Exp Anim 2013;62(3):211–7. targeting and stabilization of sarcospan is mediated by the sarcoglycan [34] Vatta M, Stetson SJ, Perez-Verdia A, Entman ML, Noon GP, Torre-Amione G, et al. subcomplex. J Cell Biol 1999;145(1):153–65. Molecular remodelling of dystrophin in patients with end-stage cardiomyopathies [63] Belkin AM, NI Zhidkova, Balzac F, Altruda F, Tomatis D, Maier A, et al. Beta 1D and reversal in patients on assistance-device therapy. Lancet 2002;359(9310): integrin displaces the beta 1A isoform in striated muscles: localization at 936–41. junctional structures and signaling potential in nonmuscle cells. J Cell Biol 1996; [35] Crossman DJ, Shen X, Jullig M, Munro M, Hou Y, Middleditch M, et al. Increased 132(1–2):211–26. collagen within the transverse tubules in human heart failure. Cardiovasc Res [64] Burkin DJ, Gu M, Hodges BL, Campanelli JT, Kaufman SJ. A functional role for 2017;113(8):879–91. specific spliced variants of the alpha7beta1 integrin in acetylcholine receptor [36] Belanto JJ, Mader TL, Eckhoff MD, Strandjord DM, Banks GB, Gardner MK, et al. clustering. J Cell Biol 1998;143(4):1067–75. Microtubule binding distinguishes dystrophin from utrophin. Proc Natl Acad Sci U [65] Belkin AM, Retta SF, Pletjushkina OY, Balzac F, Silengo L, Fassler R, et al. Muscle S A 2014;111(15):5723–8. beta1D integrin reinforces the cytoskeleton-matrix link: modulation of integrin [37] Prins KW, Humston JL, Mehta A, Tate V, Ralston E, Ervasti JM. Dystrophin is a adhesive function by alternative splicing. J Cell Biol 1997;139(6):1583–95. microtubule-associated protein. J Cell Biol 2009;186(3):363–9. [66] Crosbie RH, Heighway J, Venzke DP, Lee JC, Campbell KP. Sarcospan, the 25-kDa [38] Kombairaju P, Kerr JP, Roche JA, Pratt SJP, Lovering RM, Sussan TE, et al. Genetic transmembrane component of the dystrophin-glycoprotein complex. J Biol Chem silencing of Nrf2 enhances X-ROS in dysferlin-deficient muscle. Front Physiol 1997;272(50):31221–4. 2014;5:57. [67] Marshall JL, Chou E, Oh J, Kwok A, Burkin DJ, Crosbie-Watson RH. Dystrophin [39] Khairallah RJ, Shi G, Sbrana F, Prosser BL, Borroto C, Mazaitis MJ, et al. and utrophin expression require sarcospan: loss of alpha7 integrin exacerbates a Microtubules underlie dysfunction in duchenne muscular dystrophy. Sci Signal newly discovered muscle phenotype in sarcospan-null mice. Hum Mol Genet 2012; 2012;5(236):ra56. 21(20):4378–93. [40] Prosser BL, Ward CW, Lederer WJ. X-ROS signaling: rapid mechano-chemo [68] Marshall JL, Oh J, Chou E, Lee JA, Holmberg J, Burkin DJ, et al. Sarcospan transduction in heart. Science 2011;333(6048):1440–5. integration into laminin-binding adhesion complexes that ameliorate muscular [41] Kerr JP, Robison P, Shi G, Bogush AI, Kempema AM, Hexum JK, et al. dystrophy requires utrophin and alpha7 integrin. Hum Mol Genet 2015;24(7): Detyrosinated microtubules modulate mechanotransduction in heart and skeletal 2011–22. muscle. Nat Commun 2015;6:8526. [69] Parvatiyar MS, Marshall JL, Nguyen RT, Jordan MC, Richardson VA, Roos KP, [42] Stevenson S, Rothery S, Cullen MJ, Severs NJ. Dystrophin is not a specific et al. Sarcospan regulates cardiac isoproterenol response and prevents duchenne component of the cardiac costamere. Circ Res 1997;80(2):269–80. muscular dystrophy-associated cardiomyopathy. J Am Heart Assoc 2015;4(12). [43] Kyoi S, Otani H, Hamano A, Matsuhisa S, Akita Y, Fujiwara H, et al. Dystrophin is [70] Lebakken CS, Venzke DP, Hrstka RF, Consolino CM, Faulkner JA, Williamson RA, a possible end-target of ischemic preconditioning against cardiomyocyte oncosis et al. Sarcospan-deficient mice maintain normal muscle function. Mol Cell Biol during the early phase of reperfusion. Cardiovasc Res 2006;70(2):354–63. 2000;20(5):1669–77. [44] Straub V, Ettinger AJ, Durbeej M, Venzke DP, Cutshall S, Sanes JR, et al. epsilon- [71] Parvatiyar MS, Brownstein AJ, Kanashiro-Takeuchi RM, Collado JR, Dieseldorff sarcoglycan replaces alpha-sarcoglycan in smooth muscle to form a unique Jones KM, Gopal J, et al. Stabilization of the cardiac sarcolemma by sarcospan dystrophin-glycoprotein complex. J Biol Chem 1999;274(39):27989–96. rescues DMD-associated cardiomyopathy. JCI Insight 2019;5. [45] Straub V, Bittner RE, Leger JJ, Voit T. Direct visualization of the dystrophin [72] Panzer AA, Regmi SD, Cormier D, Danzo MT, Chen ID, Winston JB, et al. Nkx2-5 network on skeletal muscle fiber membrane. J Cell Biol 1992;119(5):1183–91. and Sarcospan genetically interact in the development of the muscular ventricular [46] Sharpe KM, Premsukh MD, Townsend D. Alterations of dystrophin-associated septum of the heart. Sci Rep 2017;7:46438. glycoproteins in the heart lacking dystrophin or dystrophin and utrophin. J Muscle [73] Ahn AH, Freener CA, Gussoni E, Yoshida M, Ozawa E, Kunkel LM. The three Res Cell Motil 2013;34(5–6):395–405. human syntrophin genes are expressed in diverse tissues, have distinct [47] Danialou G, Comtois AS, Dudley R, Karpati G, Vincent G, Des Rosiers C, et al. chromosomal locations, and each bind to dystrophin and its relatives. J Biol Chem Dystrophin-deficient cardiomyocytes are abnormally vulnerable to mechanical 1996;271(5):2724–30. stress-induced contractile failure and injury. Faseb J 2001;15(9):1655–7. [74] Newey SE, Benson MA, Ponting CP, Davies KE, Blake DJ. Alternative splicing of [48] Johnson EK, Zhang L, Adams ME, Phillips A, Freitas MA, Froehner SC, et al. dystrobrevin regulates the stoichiometry of syntrophin binding to the dystrophin Proteomic analysis reveals new cardiac-specific dystrophin-associated proteins. protein complex. Curr Biol 2000;10(20):1295–8. PloS One 2012;7(8):e43515. [75] Brenman JE, Chao DS, Gee SH, McGee AW, Craven SE, Santillano DR, et al. [49] Murphy S, Dowling P, Zweyer M, Mundegar RR, Henry M, Meleady P, et al. Interaction of nitric oxide synthase with the postsynaptic density protein PSD-95 Proteomic analysis of dystrophin deficiency and associated changes in the aged and alpha1-syntrophin mediated by PDZ domains. Cell 1996;84(5):757–67. mdx-4cv heart model of dystrophinopathy-related cardiomyopathy. J Proteomics [76] Adams ME, Mueller HA, Froehner SC. In vivo requirement of the alpha-syntrophin 2016;145:24–36. PDZ domain for the sarcolemmal localization of nNOS and aquaporin-4. J Cell Biol [50] Mulvey C, Mullen E, Ohlendieck K. The pathobiochemical role of the dystrophin- 2001;155(1):113–22. dystroglycan complex and the Ca2þ-handling apparatus in diabetes-related [77] Gee SH, Sekely SA, Lombardo C, Kurakin A, Froehner SC, Kay BK. Cyclic peptides muscle weakness (Review). Mol Med Rep 2008;1(3):297–306. as non-carboxyl-terminal ligands of syntrophin PDZ domains. J Biol Chem 1998; [51] Acharyya S, Butchbach ME, Sahenk Z, Wang H, Saji M, Carathers M, et al. 273(34):21980–7. Dystrophin glycoprotein complex dysfunction: a regulatory link between muscular [78] Hogan A, Shepherd L, Chabot J, Quenneville S, Prescott SM, Topham MK, et al. dystrophy and cancer cachexia. Canc Cell 2005;8(5):421–32. Interaction of gamma 1-syntrophin with diacylglycerol kinase-zeta. Regulation of [52] Ervasti JM, Ohlendieck K, Kahl SD, Gaver MG, Campbell KP. Deficiency of a nuclear localization by PDZ interactions. J Biol Chem 2001;276(28):26526–33. glycoprotein component of the dystrophin complex in dystrophic muscle. Nature [79] Gonzalez JP, Crassous PA, Schneider JS, Beuve A, Fraidenraich D. Neuronal nitric 1990;345(6273):315–9. oxide synthase localizes to utrophin expressing intercalated discs and stabilizes [53] Ibraghimov-Beskrovnaya O, Ervasti JM, Leveille CJ, Slaughter CA, Sernett SW, their structural integrity. Neuromuscul Disord 2015;25(12):964–76. Campbell KP. Primary structure of dystrophin-associated glycoproteins linking [80] Garbincius JF, Michele DE. Dystrophin-glycoprotein complex regulates muscle dystrophin to the extracellular matrix. Nature 1992;355(6362):696–702. nitric oxide production through mechanoregulation of AMPK signaling. Proc Natl [54] Brancaccio A, Schulthess T, Gesemann M, Engel J. Electron microscopic evidence Acad Sci U S A 2015;112(44):13663–8. for a mucin-like region in chick muscle alpha-dystroglycan. FEBS Lett 1995; [81] Nawrotzki R, Loh NY, MA Ruegg, Davies KE, Blake DJ. Characterisation of alpha- 368(1):139–42. dystrobrevin in muscle. J Cell Sci 1998;111(Pt 17):2595–605.

67 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71

[82] Sadoulet-Puccio HM, Rajala M, Kunkel LM. Dystrobrevin and dystrophin: an [111] Muntoni F, Wilson L, Marrosu G, Marrosu MG, Cianchetti C, Mestroni L, et al. interaction through coiled-coil motifs. Proc Natl Acad Sci U S A 1997;94(23): A mutation in the dystrophin gene selectively affecting dystrophin expression in 12413–8. the heart. J Clin Invest 1995;96(2):693–9. [83] Yoshida M, Hama H, Ishikawa-Sakurai M, Imamura M, Mizuno Y, Araishi K, et al. [112] Franz WM, Muller M, Muller OJ, Herrmann R, Rothmann T, Cremer M, et al. Biochemical evidence for association of dystrobrevin with the sarcoglycan- Association of nonsense mutation of dystrophin gene with disruption of sarcospan complex as a basis for understanding sarcoglycanopathy. Hum Mol sarcoglycan complex in X-linked dilated cardiomyopathy. Lancet 2000;355(9217): Genet 2000;9(7):1033–40. 1781–5. [84] Sotgia F, Lee JK, Das K, Bedford M, Petrucci TC, Macioce P, et al. Caveolin-3 [113] Bies RD, Maeda M, Roberds SL, Holder E, Bohlmeyer T, Young JB, et al. A 5’ directly interacts with the C-terminal tail of beta -dystroglycan. Identification of a dystrophin duplication mutation causes membrane deficiency of alpha- central WW-like domain within caveolin family members. J Biol Chem 2000; dystroglycan in a family with X-linked cardiomyopathy. J Mol Cell Cardiol 1997; 275(48):38048–58. 29(12):3175–88. [85] Cartaud A, Coutant S, Petrucci TC, Cartaud J. Evidence for in situ and in vitro [114] Singh SM, Bandi S, Shah DD, Armstrong G, Mallela KM. Missense mutation association between beta-dystroglycan and the subsynaptic 43K rapsyn protein. Lys18Asn in dystrophin that triggers X-linked dilated cardiomyopathy decreases Consequence for acetylcholine receptor clustering at the synapse. J Biol Chem protein stability, increases protein unfolding, and perturbs protein structure, but 1998;273(18):11321–6. does not affect protein function. PloS One 2014;9(10):e110439. [86] Willott RH, Gomes AV, Chang AN, Parvatiyar MS, Pinto JR, Potter JD. Mutations [115] Nguyen AT, He J, Taranova O, Zhang Y. Essential role of DOT1L in maintaining in Troponin that cause HCM, DCM AND RCM: what can we learn about thin normal adult hematopoiesis. Cell Res 2011;21(9):1370–3. filament function? J Mol Cell Cardiol 2010;48(5):882–92. [116] DiSalvo TG. Epigenetic regulation in heart failure: part II DNA and chromatin. [87] Brancaccio A. A molecular overview of the primary dystroglycanopathies. J Cell Cardiol Rev 2015;23(6):269–81. Mol Med 2019;23(5):3058–62. [117] Kyrychenko S, Polakova E, Kang C, Pocsai K, Ullrich ND, Niggli E, et al. [88] Ichida F, Tsubata S, Bowles KR, Haneda N, Uese K, Miyawaki T, et al. Novel gene Hierarchical accumulation of RyR post-translational modifications drives disease mutations in patients with left ventricular noncompaction or Barth syndrome. progression in dystrophic cardiomyopathy. Cardiovasc Res 2013;97(4):666–75. Circulation 2001;103(9):1256–63. [118] Colussi C, Rosati J, Straino S, Spallotta F, Berni R, Stilli D, et al. Nepsilon-lysine [89] Bushby K, Finkel R, Birnkrant DJ, Case LE, Clemens PR, Cripe L, et al. Diagnosis acetylation determines dissociation from GAP junctions and lateralization of and management of Duchenne muscular dystrophy, part 1: diagnosis, and connexin 43 in normal and dystrophic heart. Proc Natl Acad Sci U S A 2011; pharmacological and psychosocial management. Lancet Neurol 2010;9(1):77–93. 108(7):2795–800. [90] Nakamura A. X-linked dilated cardiomyopathy: a cardiospecific phenotype of [119] Johnstone VP, Viola HM, Hool LC. Dystrophic cardiomyopathy-potential role of dystrophinopathy. Pharmaceuticals (Basel) 2015;8(2):303–20. calcium in pathogenesis, treatment and novel therapies. Genes (Basel) 2017;8(4). [91] Markham LW, Michelfelder EC, Border WL, Khoury PR, Spicer RL, Wong BL, et al. [120] Lorin C, Vogeli I, Niggli E. Dystrophic cardiomyopathy: role of TRPV2 channels in Abnormalities of diastolic function precede dilated cardiomyopathy associated stretch-induced cell damage. Cardiovasc Res 2015;106(1):153–62. with Duchenne muscular dystrophy. J Am Soc Echocardiogr 2006;19(7):865–71. [121] Allen DG, Whitehead NP, Yeung EW. Mechanisms of stretch-induced muscle [92] Tsuda T, Fitzgerald KK. Dystrophic cardiomyopathy: complex pathobiological damage in normal and dystrophic muscle: role of ionic changes. J Physiol 2005; processes to generate clinical phenotype. J Cardiovasc Dev Dis 2017;4(3). 567(Pt 3):723–35. [93] McNally EM, Kaltman JR, Benson DW, Canter CE, Cripe LH, Duan D, et al. [122] Shin J, Tajrishi MM, Ogura Y, Kumar A. Wasting mechanisms in muscular Contemporary cardiac issues in duchenne muscular dystrophy. Working group of dystrophy. Int J Biochem Cell Biol 2013;45(10):2266–79. the national heart, lung, and blood institute in collaboration with parent project [123] Vallejo-Illarramendi A, Toral-Ojeda I, Aldanondo G, Lopez de Munain A. muscular dystrophy. Circulation 2015;131(18):1590–8. Dysregulation of calcium homeostasis in muscular dystrophies. Expet Rev Mol [94] Jefferies JL, Eidem BW, Belmont JW, Craigen WJ, Ware SM, Fernbach SD, et al. Med 2014;16:e16. Genetic predictors and remodeling of dilated cardiomyopathy in muscular [124] Williams IA, Allen DG. Intracellular calcium handling in ventricular myocytes dystrophy. Circulation 2005;112(18):2799–804. from mdx mice. Am J Physiol Heart Circ Physiol 2007;292(2):H846–55. [95] Kamdar F, Garry DJ. Dystrophin-deficient cardiomyopathy. J Am Coll Cardiol [125] Weller B, Karpati G, Carpenter S. Dystrophin-deficient mdx muscle fibers are 2016;67(21):2533–46. preferentially vulnerable to necrosis induced by experimental lengthening [96] Chiang DY, Allen HD, Kim JJ, Valdes SO, Wang Y, Pignatelli RH, et al. Relation of contractions. J Neurol Sci 1990;100(1–2):9–13. cardiac dysfunction to rhythm abnormalities in patients with duchenne or becker [126] Petrof BJ, Shrager JB, Stedman HH, Kelly AM, Sweeney HL. Dystrophin protects muscular dystrophies. Am J Cardiol 2016;117(8):1349–54. the sarcolemma from stresses developed during muscle contraction. Proc Natl [97] Corrado G, Lissoni A, Beretta S, Terenghi L, Tadeo G, Foglia-Manzillo G, et al. Acad Sci U S A 1993;90(8):3710–4. Prognostic value of electrocardiograms, ventricular late potentials, ventricular [127] Rando TA. The dystrophin-glycoprotein complex, cellular signaling, and the arrhythmias, and left ventricular systolic dysfunction in patients with Duchenne regulation of cell survival in the muscular dystrophies. Muscle Nerve 2001;24(12): muscular dystrophy. Am J Cardiol 2002;89(7):838–41. 1575–94. [98] Villa CR, Czosek RJ, Ahmed H, Khoury PR, Anderson JB, Knilans TK, et al. [128] Lemasters JJ, Theruvath TP, Zhong Z, Nieminen AL. Mitochondrial calcium and Ambulatory monitoring and arrhythmic outcomes in pediatric and adolescent the permeability transition in cell death. Biochim Biophys Acta 2009;1787(11): patients with duchenne muscular dystrophy. J Am Heart Assoc 2015;5(1). 1395–401. [99] Brandsema JF, Darras BT. Dystrophinopathies. Semin Neurol 2015;35(4):369–84. [129] Bhattacharya S, Das A, Ghosh S, Dasgupta R, Bagchi A. Hypoglycosylation of [100] van Putten M, van der Pijl EM, Hulsker M, Verhaart IE, Nadarajah VD, van der dystroglycan due to T192M mutation: a molecular insight behind the fact. Gene Weerd L, et al. Low dystrophin levels in heart can delay heart failure in mdx mice. 2014;537(1):108–14. J Mol Cell Cardiol 2014;69:17–23. [130] Williamson RA, Henry MD, Daniels KJ, Hrstka RF, Lee JC, Sunada Y, et al. [101] Politano L, Nigro V, Nigro G, Petretta VR, Passamano L, Papparella S, et al. Dystroglycan is essential for early embryonic development: disruption of Development of cardiomyopathy in female carriers of Duchenne and Becker Reichert’s membrane in Dag1-null mice. Hum Mol Genet 1997;6(6):831–41. muscular dystrophies. JAMA 1996;275(17):1335–8. [131] Barresi R, Campbell KP. Dystroglycan: from biosynthesis to pathogenesis of human [102] Meyers TA, Heitzman JA, Townsend D. DMD carrier model with mosaic disease. J Cell Sci 2006;119(Pt 2):199–207. dystrophin expression in the heart reveals complex vulnerability to myocardial [132] Blaeser A, Sparks S, Brown SC, Campbell K, Lu Q. Third international workshop for injury. Hum Mol Genet 2020;29(6):944–54. glycosylation defects in muscular dystrophies, 18-19 april 2013, charlotte, USA. [103] Flanigan KM. Duchenne and Becker muscular dystrophies. Neurol Clin 2014; Brain Pathol 2014;24(3):280–4. 32(3):671–88. viii. [133] Muntoni F. Journey into muscular dystrophies caused by abnormal glycosylation. [104] Bradley WG, Jones MZ, Mussini JM, Fawcett PR. Becker-type muscular dystrophy. Acta Myol 2004;23(2):79–84. Muscle Nerve 1978;1(2):111–32. [134] Martin PT. The dystroglycanopathies: the new disorders of O-linked glycosylation. [105] Komaki R, Hashimoto Y, Mori-Yoshimura M, Oya Y, Takizawa H, Minami N, et al. Semin Pediatr Neurol 2005;12(3):152–8. Severe cardiac involvement with preserved truncated dystrophin expression in [135] Hara Y, Kanagawa M, Kunz S, Yoshida-Moriguchi T, Satz JS, Kobayashi YM, et al. Becker muscular dystrophy by þ1G>A DMD splice-site mutation: a case report. Like-acetylglucosaminyltransferase (LARGE)-dependent modification of J Hum Genet 2020;65(10):903–9. dystroglycan at Thr-317/319 is required for laminin binding and arenavirus [106] Berko BA, Swift M. X-linked dilated cardiomyopathy. N Engl J Med 1987;316(19): infection. Proc Natl Acad Sci U S A 2011;108(42):17426–31. 1186–91. [136] Chung W, Campanelli JT. WW and EF hand domains of dystrophin-family proteins [107] Towbin JA, Hejtmancik JF, Brink P, Gelb B, Zhu XM, Chamberlain JS, et al. X- mediate dystroglycan binding. Mol Cell Biol Res Commun 1999;2(3):162–71. linked dilated cardiomyopathy. Molecular genetic evidence of linkage to the [137] Michele DE, Kabaeva Z, Davis SL, Weiss RM, Campbell KP. Dystroglycan matrix Duchenne muscular dystrophy (dystrophin) gene at the Xp21 locus. Circulation receptor function in cardiac myocytes is important for limiting activity-induced 1993;87(6):1854–65. myocardial damage. Circ Res 2009;105(10):984–93. [108] Muntoni F, Cau M, Ganau A, Congiu R, Arvedi G, Mateddu A, et al. Brief report: [138] Barresi R, Michele DE, Kanagawa M, Harper HA, Dovico SA, Satz JS, et al. LARGE deletion of the dystrophin muscle-promoter region associated with X-linked can functionally bypass alpha-dystroglycan glycosylation defects in distinct dilated cardiomyopathy. N Engl J Med 1993;329(13):921–5. congenital muscular dystrophies. Nat Med 2004;10(7):696–703. [109] Yoshida K, Nakamura A, Yazaki M, Ikeda S, Takeda S. Insertional mutation by [139] Ujihara Y, Kanagawa M, Mohri S, Takatsu S, Kobayashi K, Toda T, et al. transposable element, L1, in the DMD gene results in X-linked dilated Elimination of fukutin reveals cellular and molecular pathomechanisms in cardiomyopathy. Hum Mol Genet 1998;7(7):1129–32. muscular dystrophy-associated heart failure. Nat Commun 2019;10(1):5754. [110] Neri M, Valli E, Alfano G, Bovolenta M, Spitali P, Rapezzi C, et al. The absence of [140] Angelini C, Fanin M, Freda MP, Duggan DJ, Siciliano G, Hoffman EP. The clinical dystrophin brain isoform expression in healthy human heart ventricles explains spectrum of sarcoglycanopathies. Neurology 1999;52(1):176–9. the pathogenesis of 5’ X-linked dilated cardiomyopathy. BMC Med Genet 2012;13: 20.

68 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71

[141] Alavi A, Esmaeili S, Nilipour Y, Nafissi S, Tonekaboni SH, Zamani G, et al. [170] Bergmann O, Zdunek S, Alkass K, Druid H, Bernard S, Frisen J. Identification of LGMD2E is the most common type of sarcoglycanopathies in the Iranian cardiomyocyte nuclei and assessment of ploidy for the analysis of cell turnover. population. J Neurogenet 2017;31(3):161–9. Exp Cell Res 2011;317(2):188–94. [142] Fanin M, Angelini C. Regeneration in sarcoglycanopathies: expression studies of [171] Kajstura J, Gurusamy N, Ogorek B, Goichberg P, Clavo-Rondon C, Hosoda T, et al. sarcoglycans and other muscle proteins. J Neurol Sci 1999;165(2):170–7. Myocyte turnover in the aging human heart. Circ Res 2010;107(11):1374–86. [143] Draviam R, Billington L, Senchak A, Hoffman EP, Watkins SC. Confocal analysis of [172] Walsh S, Ponten A, Fleischmann BK, Jovinge S. Cardiomyocyte cell cycle control the dystrophin protein complex in muscular dystrophy. Muscle Nerve 2001;24(2): and growth estimation in vivo–an analysis based on cardiomyocyte nuclei. 262–72. Cardiovasc Res 2010;86(3):365–73. [144] Klinge L, Dekomien G, Aboumousa A, Charlton R, Epplen JT, Barresi R, et al. [173] Bezanilla M, Gladfelter AS, Kovar DR, Lee WL. Cytoskeletal dynamics: a view from Sarcoglycanopathies: can muscle immunoanalysis predict the genotype? the membrane. J Cell Biol 2015;209(3):329–37. Neuromuscul Disord 2008;18(12):934–41. [174] Peter AK, Cheng H, Ross RS, Knowlton KU, Chen J. The costamere bridges [145] Vainzof M, Passos-Bueno MR, Canovas M, Moreira ES, Pavanello RC, Marie SK, sarcomeres to the sarcolemma in striated muscle. Prog Pediatr Cardiol 2011;31(2): et al. The sarcoglycan complex in the six autosomal recessive limb-girdle muscular 83–8. dystrophies. Hum Mol Genet 1996;5(12):1963–9. [175] Dupont S, Morsut L, Aragona M, Enzo E, Giulitti S, Cordenonsi M, et al. Role of [146] Bonnemann CG, Finkel RS. Sarcolemmal proteins and the spectrum of limb-girdle YAP/TAZ in mechanotransduction. Nature 2011;474(7350):179–83. muscular dystrophies. Semin Pediatr Neurol 2002;9(2):81–99. [176] Morikawa Y, Heallen T, Leach J, Xiao Y, Martin JF. Dystrophin-glycoprotein [147] Matsumura K, Zhong D, Saito F, Arai K, Adachi K, Kawai H, et al. Proteolysis of complex sequesters Yap to inhibit cardiomyocyte proliferation. Nature 2017; beta-dystroglycan in muscular diseases. Neuromuscul Disord 2005;15(5):336–41. 547(7662):227–31. [148] Sandona D, Betto R. Sarcoglycanopathies: molecular pathogenesis and therapeutic [177] Xin M, Kim Y, Sutherland LB, Murakami M, Qi X, McAnally J, et al. Hippo pathway prospects. Expet Rev Mol Med 2009;11:e28. effector Yap promotes cardiac regeneration. Proc Natl Acad Sci U S A 2013; [149] Holt KH, Campbell KP. Assembly of the sarcoglycan complex. Insights for 110(34):13839–44. muscular dystrophy. J Biol Chem 1998;273(52):34667–70. [178] Heallen T, Zhang M, Wang J, Bonilla-Claudio M, Klysik E, Johnson RL, et al. Hippo [150] Holt KH, Lim LE, Straub V, Venzke DP, Duclos F, Anderson RD, et al. Functional pathway inhibits Wnt signaling to restrain cardiomyocyte proliferation and heart rescue of the sarcoglycan complex in the BIO 14.6 hamster using delta-sarcoglycan size. Science 2011;332(6028):458–61. gene transfer. Mol Cell 1998;1(6):841–8. [179] Leach JP, Heallen T, Zhang M, Rahmani M, Morikawa Y, Hill MC, et al. Hippo [151] Ryoke T, Gu Y, Ikeda Y, Martone ME, Oh SS, Jeon ES, et al. Apoptosis and oncosis pathway deficiency reverses systolic heart failure after infarction. Nature 2017; in the early progression of left ventricular dysfunction in the cardiomyopathic 550(7675):260–4. hamster. Basic Res Cardiol 2002;97(1):65–75. [180] Kshitiz ME Hubbi, Ahn EH, Downey J, Afzal J, Kim DH, et al. Matrix rigidity [152] Sakamoto A. Molecular pathogenesis of severe cardiomyopathy in the TO-2 controls endothelial differentiation and morphogenesis of cardiac precursors. Sci hamster. Exp Clin Cardiol 2003;8(3):143–6. Signal 2012;5(227):ra41. [153] Toyo-Oka T, Kawada T, Nakata J, Xie H, Urabe M, Masui F, et al. Translocation [181] Bassat E, Mutlak YE, Genzelinakh A, Shadrin IY, Baruch Umansky K, Yifa O, et al. and cleavage of myocardial dystrophin as a common pathway to advanced heart The extracellular matrix protein agrin promotes heart regeneration in mice. failure: a scheme for the progression of cardiac dysfunction. Proc Natl Acad Sci U S Nature 2017;547(7662):179–84. A 2004;101(19):7381–5. [182] Morikawa Y, Zhang M, Heallen T, Leach J, Tao G, Xiao Y, et al. Actin cytoskeletal [154] Kondoh H, Sawa Y, Fukushima N, Matsumiya G, Miyagawa S, Kitagawa- remodeling with protrusion formation is essential for heart regeneration in Hippo- Sakakida S, et al. Reorganization of cytoskeletal proteins and prolonged life deficient mice. Sci Signal 2015;8(375):ra41. expectancy caused by hepatocyte growth factor in a hamster model of late-phase [183] Richardson GD, Laval S, Owens WA. Cardiomyocyte regeneration in the mdx dilated cardiomyopathy. J Thorac Cardiovasc Surg 2005;130(2):295–302. mouse model of nonischemic cardiomyopathy. Stem Cell Dev 2015;24(14): [155] Hack AA, Ly CT, Jiang F, Clendenin CJ, Sigrist KS, Wollmann RL, et al. Gamma- 1672–9. sarcoglycan deficiency leads to muscle membrane defects and apoptosis [184] Halder G, Dupont S, Piccolo S. Transduction of mechanical and cytoskeletal cues independent of dystrophin. J Cell Biol 1998;142(5):1279–87. by YAP and TAZ. Nat Rev Mol Cell Biol 2012;13(9):591–600. [156] Coral-Vazquez R, Cohn RD, Moore SA, Hill JA, Weiss RM, Davisson RL, et al. [185] Stetson SJ, Perez-Verdia A, Vatta M, Bowles NE, Towbin JA, Torre-Amione G. Disruption of the sarcoglycan-sarcospan complex in vascular smooth muscle: a Improved myocardial structure following LVAD support: effect of unloading on novel mechanism for cardiomyopathy and muscular dystrophy. Cell 1999;98(4): dystrophin expression. J Heart Lung Transplant 2001;20(2):240. 465–74. [186] Birks EJ, Hall JL, Barton PJ, Grindle S, Latif N, Hardy JP, et al. Gene profiling [157] Matsunari H, Honda M, Watanabe M, Fukushima S, Suzuki K, Miyagawa S, et al. changes in cytoskeletal proteins during clinical recovery after left ventricular- Pigs with delta-sarcoglycan deficiency exhibit traits of genetic cardiomyopathy. assist device support. Circulation 2005;112(9 Suppl):I57–64. Lab Invest 2020;100(6):887–99. [187] Birks EJ. Molecular changes after left ventricular assist device support for heart [158] Lancioni A, Rotundo IL, Kobayashi YM, D’Orsi L, Aurino S, Nigro G, et al. failure. Circ Res 2013;113(6):777–91. Combined deficiency of alpha and epsilon sarcoglycan disrupts the cardiac [188] Vatta M, Stetson SJ, Jimenez S, Entman ML, Noon GP, Bowles NE, et al. Molecular dystrophin complex. Hum Mol Genet 2011;20(23):4644–54. normalization of dystrophin in the failing left and right ventricle of patients [159] Araishi K, Sasaoka T, Imamura M, Noguchi S, Hama H, Wakabayashi E, et al. Loss treated with either pulsatile or continuous flow-type ventricular assist devices. of the sarcoglycan complex and sarcospan leads to muscular dystrophy in beta- J Am Coll Cardiol 2004;43(5):811–7. sarcoglycan-deficient mice. Hum Mol Genet 1999;8(9):1589–98. [189] Perri G, Filippelli S, Adorisio R, Iacobelli R, Iodice F, Testa G, et al. Left ventricular [160] Cohn RD, Durbeej M, Moore SA, Coral-Vazquez R, Prouty S, Campbell KP. assist device as destination therapy in cardiac end-stage dystrophinopathies: Prevention of cardiomyopathy in mouse models lacking the smooth muscle midterm results. J Thorac Cardiovasc Surg 2017;153(3):669–74. sarcoglycan-sarcospan complex. J Clin Invest 2001;107(2):R1–7. [190] Drakos SG, Mehra MR. Clinical myocardial recovery during long-term mechanical [161] Daicho T, Daisho Y, Kojima S, Takano S, Tejima Y, Marunouchi T, et al. Alterations support in advanced heart failure: insights into moving the field forward. J Heart in dystrophin-related glycoproteins in development of right ventricular failure in Lung Transplant 2016;35(4):413–20. rats. J Pharmacol Sci 2009;111(4):405–15. [191] Birks EJ, Tansley PD, Hardy J, George RS, Bowles CT, Burke M, et al. Left [162] Lemler MS, Bies RD, Frid MG, Sastravaha A, Zisman LS, Bohlmeyer T, et al. ventricular assist device and drug therapy for the reversal of heart failure. N Engl J Myocyte cytoskeletal disorganization and right heart failure in hypoxia-induced Med 2006;355(18):1873–84. neonatal pulmonary hypertension. Am J Physiol Heart Circ Physiol 2000;279(3): [192] Birks EJ, McGee Jr EC, Aaronson KD, Boyce S, Cotts WG, Najjar SS, et al. An H1365–76. examination of survival by sex and race in the HeartWare ventricular assist device [163] Kostin S, Scholz D, Shimada T, Maeno Y, Mollnau H, Hein S, et al. The internal and for the treatment of advanced heart failure (ADVANCE) bridge to transplant (BTT) external protein scaffold of the T-tubular system in cardiomyocytes. Cell Tissue and continued access protocol trials. J Heart Lung Transplant 2015;34(6):815–24. Res 1998;294(3):449–60. [193] Margulies KB, Matiwala S, Cornejo C, Olsen H, Craven WA, Bednarik D. Mixed [164] Armstrong SC, Latham CA, Shivell CL, Ganote CE. Ischemic loss of sarcolemmal messages: transcription patterns in failing and recovering human myocardium. dystrophin and spectrin: correlation with myocardial injury. J Mol Cell Cardiol Circ Res 2005;96(5):592–9. 2001;33(6):1165–79. [194] Topkara VK, Chambers KT, Yang KC, Tzeng HP, Evans S, Weinheimer C, et al. [165] Rodriguez M, Cai WJ, Kostin S, Lucchesi BR, Schaper J. Ischemia depletes Functional significance of the discordance between transcriptional profile and left dystrophin and inhibits protein synthesis in the canine heart: mechanisms of ventricular structure/function during reverse remodeling. JCI Insight 2016;1(4): myocardial ischemic injury. J Mol Cell Cardiol 2005;38(5):723–33. e86038. [166] Kyoi S, Otani H, Sumida T, Okada T, Osako M, Imamura H, et al. Loss of [195] Uriel N, Sayer G, Annamalai S, Kapur NK, Burkhoff D. Mechanical unloading in intracellular dystrophin: a potential mechanism for myocardial reperfusion injury. heart failure. J Am Coll Cardiol 2018;72(5):569–80. Circ J 2003;67(8):725–7. [196] Rajdev A, Groh WJ. Arrhythmias in the muscular dystrophies. Card Electrophysiol [167] Shojima T, Hayashida N, Nishi A, Takagi K, Hori H, Yoshikawa K, et al. Effects of Clin 2015;7(2):303–8. nicorandil preconditioning on membrane dystrophin. Eur J Cardio Thorac Surg [197] Wehling-Henricks M, Jordan MC, Roos KP, Deng B, Tidball JG. Cardiomyopathy in 2006;30(3):472–9. dystrophin-deficient hearts is prevented by expression of a neuronal nitric oxide [168] Moriguchi A, Otani H, Yoshioka K, Shimazu T, Fujita M, Okazaki T, et al. synthase transgene in the myocardium. Hum Mol Genet 2005;14(14):1921–33. Inhibition of contractile activity during postconditioning enhances [198] Burr AR, Molkentin JD. Genetic evidence in the mouse solidifies the calcium cardioprotection by restoring sarcolemmal dystrophin through hypothesis of myofiber death in muscular dystrophy. Cell Death Differ 2015;22(9): phosphatidylinositol 3-kinase. Circ J 2010;74(11):2393–402. 1402–12. [169] Bergmann O, Bhardwaj RD, Bernard S, Zdunek S, Barnabe-Heider F, Walsh S, et al. [199] Sachs F. Stretch-activated ion channels: what are they? Physiology (Bethesda) Evidence for cardiomyocyte renewal in humans. Science 2009;324(5923):98–102. 2010;25(1):50–6.

69 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71

[200] Fanchaouy M, Polakova E, Jung C, Ogrodnik J, Shirokova N, Niggli E. Pathways of [229] Gianni L, Herman EH, Lipshultz SE, Minotti G, Sarvazyan N, Sawyer DB. abnormal stress-induced Ca2þ influx into dystrophic mdx cardiomyocytes. Cell Anthracycline cardiotoxicity: from bench to bedside. J Clin Oncol 2008;26(22): Calcium 2009;46(2):114–21. 3777–84. [201] Koenig X, Rubi L, Obermair GJ, Cervenka R, Dang XB, Lukacs P, et al. Enhanced [230] Annane D, Bellissant E, Cavaillon JM. Septic shock. Lancet 2005;365(9453): currents through L-type calcium channels in cardiomyocytes disturb the 63–78. electrophysiology of the dystrophic heart. Am J Physiol Heart Circ Physiol 2014; [231] Vieillard-Baron A. Septic cardiomyopathy. Ann Intensive Care 2011;1(1):6. 306(4):H564–73. [232] Klietsch R, Ervasti JM, Arnold W, Campbell KP, Jorgensen AO. Dystrophin- [202] Jung C, Martins AS, Niggli E, Shirokova N. Dystrophic cardiomyopathy: glycoprotein complex and laminin colocalize to the sarcolemma and transverse amplification of cellular damage by Ca2þ signalling and reactive oxygen species- tubules of cardiac muscle. Circ Res 1993;72(2):349–60. generating pathways. Cardiovasc Res 2008;77(4):766–73. [233] Hein S, Kostin S, Heling A, Maeno Y, Schaper J. The role of the cytoskeleton in [203] Sarma S, Li N, van Oort RJ, Reynolds C, Skapura DG, Wehrens XH. Genetic heart failure. Cardiovasc Res 2000;45(2):273–8. inhibition of PKA phosphorylation of RyR2 prevents dystrophic cardiomyopathy. [234] Kostin S, Hein S, Arnon E, Scholz D, Schaper J. The cytoskeleton and related Proc Natl Acad Sci U S A 2010;107(29):13165–70. proteins in the human failing heart. Heart Fail Rev 2000;5(3):271–80. [204] van Oort RJ, Garbino A, Wang W, Dixit SS, Landstrom AP, Gaur N, et al. Disrupted [235] Suzuki T, Morisaki H, Serita R, Yamamoto M, Kotake Y, Ishizaka A, et al. Infusion junctional membrane complexes and hyperactive ryanodine receptors after acute of the beta-adrenergic blocker esmolol attenuates myocardial dysfunction in septic junctophilin knockdown in mice. Circulation 2011;123(9):979–88. rats. Crit Care Med 2005;33(10):2294–301. [205] Ather S, Wang W, Wang Q, Li N, Anderson ME, Wehrens XH. Inhibition of CaMKII [236] Celes MR, Torres-Duenas D, Prado CM, Campos EC, Moreira JE, Cunha FQ, et al. phosphorylation of RyR2 prevents inducible ventricular arrhythmias in mice with Increased sarcolemmal permeability as an early event in experimental septic Duchenne muscular dystrophy. Heart Rhythm 2013;10(4):592–9. cardiomyopathy: a potential role for oxidative damage to lipids and proteins. [206] Fontes MS, van Veen TA, de Bakker JM, HV van Rijen. Functional consequences of Shock 2010;33(3):322–31. abnormal Cx43 expression in the heart. Biochim Biophys Acta 2012;1818(8): [237] Ventura Spagnolo E, Mondello C, Di Mauro D, Vermiglio G, Asmundo A, 2020–9. Filippini E, et al. Analysis on sarcoglycans expression as markers of septic [207] Gonzalez JP, Ramachandran J, Xie LH, Contreras JE, Fraidenraich D. Selective cardiomyopathy in sepsis-related death. Int J Leg Med 2018;132(6):1685–92. Connexin43 inhibition prevents isoproterenol-induced arrhythmias and lethality [238] Baboonian C, Davies MJ, Booth JC, McKenna WJ. Coxsackie B viruses and human in muscular dystrophy mice. Sci Rep 2015;5:13490. heart disease. Curr Top Microbiol Immunol 1997;223:31–52. [208] Himelman E, Lillo MA, Nouet J, Gonzalez JP, Zhao Q, Xie LH, et al. Prevention of [239] Gupta HL, Khare S, Biswas A, Chattopadhya D, Kumari S. Coxsackie B virus in the connexin-43 remodeling protects against Duchenne muscular dystrophy etiology of heart diseases in Delhi. J Commun Dis 1995;27(4):223–8. cardiomyopathy. J Clin Invest 2020. [240] McCarthy 3rd RE, Boehmer JP, Hruban RH, Hutchins GM, Kasper EK, Hare JM, [209] Rybakova IN, Humston JL, Sonnemann KJ, Ervasti JM. Dystrophin and utrophin et al. Long-term outcome of fulminant myocarditis as compared with acute bind actin through distinct modes of contact. J Biol Chem 2006;281(15): (nonfulminant) myocarditis. N Engl J Med 2000;342(10):690–5. 9996–10001. [241] Kandolf R, Klingel K, Zell R, Selinka HC, Raab U, Schneider-Brachert W, et al. [210] Iwata Y, Sampaolesi M, Shigekawa M, Wakabayashi S. Syntrophin is an actin- Molecular pathogenesis of enterovirus-induced myocarditis: virus persistence and binding protein the cellular localization of which is regulated through cytoskeletal chronic inflammation. Intervirology 1993;35(1–4):140–51. reorganization in skeletal muscle cells. Eur J Cell Biol 2004;83(10):555–65. [242] Spartalis M, E Tzatzaki, E Spartalis, C Damaskos, S Mavrogeni and V Voudris. [211] Bossuyt J, Taylor BE, James-Kracke M, Hale CC. Evidence for cardiac sodium- Parvovirus. calcium exchanger association with caveolin-3. FEBS Lett 2002;511(1–3):113–7. [243] Bowles NE, Vallejo J. Viral causes of cardiac inflammation. Curr Opin Cardiol [212] Feron O, Kelly RA. Gaining respectability: membrane-delimited, caveolar- 2003;18(3):182–8. restricted activation of ion channels. Circ Res 2002;90(4):369–70. [244] Reddy S, Eliassen E, Krueger GR, Das BB. Human herpesvirus 6-induced [213] Venema RC, Ju H, Zou R, Ryan JW, Venema VJ. Subunit interactions of inflammatory cardiomyopathy in immunocompetent children. Ann Pediatr Cardiol endothelial nitric-oxide synthase. Comparisons to the neuronal and inducible 2017;10(3):259–68. nitric-oxide synthase isoforms. J Biol Chem 1997;272(2):1276–82. [245] Matsumori A, Yutani C, Ikeda Y, Kawai S, Sasayama S. Hepatitis C virus from the [214] Campbell KP, Kahl SD. Association of dystrophin and an integral membrane hearts of patients with myocarditis and cardiomyopathy. Lab Invest 2000;80(7): glycoprotein. Nature 1989;338(6212):259–62. 1137–42. [215] Durbeej M, Campbell KP. Muscular dystrophies involving the dystrophin- [246] Chimenti C, Russo A, Pieroni M, Calabrese F, Verardo R, Thiene G, et al. glycoprotein complex: an overview of current mouse models. Curr Opin Genet Dev Intramyocyte detection of Epstein-Barr virus genome by laser capture 2002;12(3):349–61. microdissection in patients with inflammatory cardiomyopathy. Circulation 2004; [216] McMahon CJ, Vatta M, Fraser Jr CD, Towbin JA, Chang AC. Altered dystrophin 110(23):3534–9. expression in the right atrium of a patient after Fontan procedure with atrial [247] Schultz JC, Hilliard AA, Cooper Jr LT, Rihal CS. Diagnosis and treatment of viral flutter. Heart 2004;90(12):e65. myocarditis. Mayo Clin Proc 2009;84(11):1001–9. [217] Reilly SN, Liu X, Carnicer R, Recalde A, Muszkiewicz A, Jayaram R, et al. Up- [248] Puntmann V, Nagel E. Cardiac involvement after recovering from COVID-19-reply. regulation of miR-31 in human atrial fibrillation begets the arrhythmia by JAMA Cardiol 2020. depleting dystrophin and neuronal nitric oxide synthase. Sci Transl Med 2016; [249] Henry MD, Campbell KP. A role for dystroglycan in basement membrane 8(340):340ra374. assembly. Cell 1998;95(6):859–70. [218] Vad OB, Paludan-Muller C, Ahlberg G, Kalsto SM, Ghouse J, Andreasen L, et al. [250] Cohn RD, Henry MD, DE Michele, Barresi R, Saito F, Moore SA, et al. Disruption of Loss-of-Function variants in cytoskeletal genes are associated with early-onset DAG1 in differentiated skeletal muscle reveals a role for dystroglycan in muscle atrial fibrillation. J Clin Med 2020;9(2). regeneration. Cell 2002;110(5):639–48. [219] Takemura G, Fujiwara H. Doxorubicin-induced cardiomyopathy from the [251] Cao W, Henry MD, Borrow P, Yamada H, Elder JH, Ravkov EV, et al. Identification cardiotoxic mechanisms to management. Prog Cardiovasc Dis 2007;49(5):330–52. of alpha-dystroglycan as a receptor for lymphocytic choriomeningitis virus and [220] Singal PK, Deally CM, Weinberg LE. Subcellular effects of adriamycin in the heart: Lassa fever virus. Science 1998;282(5396):2079–81. a concise review. J Mol Cell Cardiol 1987;19(8):817–28. [252] Kanagawa M, Saito F, Kunz S, Yoshida-Moriguchi T, Barresi R, Kobayashi YM, [221] Kalyanaraman B, Perez-Reyes E, Mason RP. Spin-trapping and direct electron spin et al. Molecular recognition by LARGE is essential for expression of functional resonance investigations of the redox metabolism of quinone anticancer drugs. dystroglycan. Cell 2004;117(7):953–64. Biochim Biophys Acta 1980;630(1):119–30. [253] de Greef JC, Slutter B, Anderson ME, Hamlyn R, O’Campo Landa R, McNutt EJ, [222] Kalivendi SV, Kotamraju S, Zhao H, Joseph J, Kalyanaraman B. Doxorubicin- et al. Protective role for the N-terminal domain of alpha-dystroglycan in Influenza induced apoptosis is associated with increased transcription of endothelial nitric- A virus proliferation. Proc Natl Acad Sci U S A 2019;116(23):11396–401. oxide synthase. Effect of antiapoptotic antioxidants and calcium. J Biol Chem [254] Wessely R, Klingel K, Santana LF, Dalton N, Hongo M, Jonathan Lederer W, et al. 2001;276(50):47266–76. Transgenic expression of replication-restricted enteroviral genomes in heart [223] Wang L, Ma W, Markovich R, Chen JW, Wang PH. Regulation of cardiomyocyte muscle induces defective excitation-contraction coupling and dilated apoptotic signaling by insulin-like growth factor I. Circ Res 1998;83(5):516–22. cardiomyopathy. J Clin Invest 1998;102(7):1444–53. [224] Arola OJ, Saraste A, Pulkki K, Kallajoki M, Parvinen M, Voipio-Pulkki LM. Acute [255] Andreoletti L, Venteo L, Douche-Aourik F, Canas F, Lorin de la Grandmaison G, doxorubicin cardiotoxicity involves cardiomyocyte apoptosis. Canc Res 2000; Jacques J, et al. Active Coxsackieviral B infection is associated with disruption of 60(7):1789–92. dystrophin in endomyocardial tissue of patients who died suddenly of acute [225] Kim Y, Ma AG, Kitta K, Fitch SN, Ikeda T, Ihara Y, et al. Anthracycline-induced myocardial infarction. J Am Coll Cardiol 2007;50(23):2207–14. suppression of GATA-4 transcription factor: implication in the regulation of [256] Lim BK, Peter AK, Xiong D, Narezkina A, Yung A, Dalton ND, et al. Inhibition of cardiac myocyte apoptosis. Mol Pharmacol 2003;63(2):368–77. Coxsackievirus-associated dystrophin cleavage prevents cardiomyopathy. J Clin [226] Aries A, Paradis P, Lefebvre C, Schwartz RJ, Nemer M. Essential role of GATA-4 in Invest 2013;123(12):5146–51. cell survival and drug-induced cardiotoxicity. Proc Natl Acad Sci U S A 2004; [257] Barnabei MS, Sjaastad FV, Townsend D, Bedada FB, Metzger JM. Severe 101(18):6975–80. dystrophic cardiomyopathy caused by the enteroviral protease 2A-mediated C- [227] Dudnakova TV, Lakomkin VL, Tsyplenkova VG, Shekhonin BV, Shirinsky VP, terminal dystrophin cleavage fragment. Sci Transl Med 2015;7(294):294ra106. Kapelko VI. Alterations in myocardial cytoskeletal and regulatory protein [258] Yun SH, Shin HH, Ju ES, Lee YJ, Lim BK, Jeon ES. Inhibition of RNA helicase expression following a single Doxorubicin injection. J Cardiovasc Pharmacol activity prevents Coxsackievirus B3-induced myocarditis in human iPS 2003;41(5):788–94. cardiomyocytes. Int J Mol Sci 2020;21(9). [228] Deng S, Kulle B, Hosseini M, Schluter G, Hasenfuss G, Wojnowski L, et al. [259] Chen C, Zhou Y, Wang DW. SARS-CoV-2: a potential novel etiology of fulminant Dystrophin-deficiency increases the susceptibility to doxorubicin-induced myocarditis. Herz; 2020. cardiotoxicity. Eur J Heart Fail 2007;9(10):986–94. [260] Zheng YY, Ma YT, Zhang JY, Xie X. COVID-19 and the cardiovascular system. Nat Rev Cardiol 2020.

70 I.C. Valera et al. Advances in Medical Sciences 66 (2021) 52–71

[261] Inciardi RM, Lupi L, Zaccone G, Italia L, Raffo M, Tomasoni D, et al. Cardiac [284] Bartos JA, Matsuura TR, Tsangaris A, Olson M, McKnite SH, Rees JN, et al. involvement in a patient with coronavirus disease 2019 (COVID-19). JAMA Intracoronary poloxamer 188 prevents reperfusion injury in a porcine model of Cardiol 2020. ST-segment elevation myocardial infarction. JACC Basic Transl Sci 2016;1(4): [262] Machado FS, Tyler KM, Brant F, Esper L, Teixeira MM, Tanowitz HB. Pathogenesis 224–34. of Chagas disease: time to move on. Front Biosci (Elite Ed) 2012;4:1743–58. [285] Weisleder N, Takizawa N, Lin P, Wang X, Cao C, Zhang Y, et al. Recombinant [263] Rassi Jr A, JAN Marin, Rassi A. Chronic Chagas cardiomyopathy: a review of the MG53 protein modulates therapeutic cell membrane repair in treatment of main pathogenic mechanisms and the efficacy of aetiological treatment following muscular dystrophy. Sci Transl Med 2012;4(139):139ra185. the BENznidazole Evaluation for Interrupting Trypanosomiasis (BENEFIT) trial. [286] Houang EM, Bartos J, Hackel BJ, Lodge TP, Yannopoulos D, Bates FS, et al. Cardiac Mem Inst Oswaldo Cruz 2017;112(3):224–35. muscle membrane stabilization in myocardial reperfusion injury. JACC Basic [264] Malvestio LM, Celes MR, Jelicks LA, Tanowitz HB, Prado CM. Dantrolene improves Transl Sci 2019;4(2):275–87. in vitro structural changes induced by serum from Trypanosoma cruzi-infected [287] Doroudgar S, Glembotski CC. ATF6 [corrected] and thrombospondin 4: the mice. Parasitol Res 2017;116(1):429–33. dynamic duo of the adaptive endoplasmic reticulum stress response. Circ Res [265] Gascon J, Bern C, Pinazo MJ. Chagas disease in Spain, the United States and other 2013;112(1):9–12. non-endemic countries. Acta Trop 2010;115(1–2):22–7. [288] Lynch JM, Maillet M, Vanhoutte D, Schloemer A, Sargent MA, Blair NS, et al. [266] Develoux M, Lescure FX, Jaureguiberry S, Jeannel D, Elghouzzi MH, Gay F, et al. A thrombospondin-dependent pathway for a protective ER stress response. Cell [Emergence of Chagas’ disease in Europe: description of the first cases observed in 2012;149(6):1257–68. Latin American immigrants in mainland France]. Med Trop (Mars) 2010;70(1): [289] Okada H, Lai NC, Kawaraguchi Y, Liao P, Copps J, Sugano Y, et al. Integrins 38–42. protect cardiomyocytes from ischemia/reperfusion injury. J Clin Invest 2013; [267] Finsterer J, Cripe L. Treatment of dystrophin cardiomyopathies. Nat Rev Cardiol 123(10):4294–308. 2014;11(3):168–79. [290] Moloughney JG, Weisleder N. Poloxamer 188 (p188) as a membrane resealing [268] Cahill TJ, Choudhury RP, Riley PR. Heart regeneration and repair after myocardial reagent in biomedical applications. Recent Pat Biotechnol 2012;6(3):200–11. infarction: translational opportunities for novel therapeutics. Nat Rev Drug Discov [291] Townsend D, Turner I, Yasuda S, Martindale J, Davis J, Shillingford M, et al. 2017;16(10):699–717. Chronic administration of membrane sealant prevents severe cardiac injury and [269] Telukuntla KS, Suncion VY, Schulman IH, Hare JM. The advancing field of cell- ventricular dilatation in dystrophic dogs. J Clin Invest 2010;120(4):1140–50. based therapy: insights and lessons from clinical trials. J Am Heart Assoc 2013; [292] Spurney CF, Guerron AD, Yu Q, Sali A, van der Meulen JH, Hoffman EP, et al. 2(5):e000338. Membrane sealant Poloxamer P188 protects against isoproterenol induced [270] Vaseghi H, Liu J, Qian L. Molecular barriers to direct cardiac reprogramming. cardiomyopathy in dystrophin deficient mice. BMC Cardiovasc Disord 2011;11:20. Protein Cell 2017;8(10):724–34. [293] Hunter RL, Luo AZ, Zhang R, Kozar RA, Moore FA. Poloxamer 188 inhibition of [271] Gao X, Lu A, Tang Y, Schneppendahl J, Liebowitz AB, Scibetta AC, et al. Influences ischemia/reperfusion injury: evidence for a novel anti-adhesive mechanism. Ann of donor and host age on human muscle-derived stem cell-mediated bone Clin Lab Sci 2010;40(2):115–25. regeneration. Stem Cell Res Ther 2018;9(1):316. [294] Musharrafieh R, Kitamura N, Hu Y, Wang J. Development of broad-spectrum [272] Yanamandala M, Zhu W, Garry DJ, Kamp TJ, Hare JM, Jun HW, et al. Overcoming enterovirus antivirals based on quinoline scaffold. Bioorg Chem 2020;101: the roadblocks to cardiac cell therapy using tissue engineering. J Am Coll Cardiol 103981. 2017;70(6):766–75. [295] Bar A, Cohen S. Inducing endogenous cardiac regeneration: can biomaterials [273] Ali H, Braga L, Giacca M. Cardiac regeneration and remodelling of the connect the dots? Front Bioeng Biotechnol 2020;8:126. cardiomyocyte cytoarchitecture. FEBS J 2020;287(3):417–38. [296] Kapnisi M, Mansfield C, Marijon C, Guex AG, Perbellini F, Bardi I, et al. Auxetic [274] Eschenhagen T, Bolli R, Braun T, Field LJ, Fleischmann BK, Frisen J, et al. cardiac patches with tunable mechanical and conductive properties toward Cardiomyocyte regeneration: a consensus statement. Circulation 2017;136(7): treating myocardial infarction. Adv Funct Mater 2018;28(21):1800618. 680–6. [297] Simpson D, Liu H, Fan TH, Nerem R, Dudley Jr SC. A tissue engineering approach [275] Tiburcy M, Hudson JE, Balfanz P, Schlick S, Meyer T, Chang Liao ML, et al. to progenitor cell delivery results in significant cell engraftment and improved Defined engineered human myocardium with advanced maturation for myocardial remodeling. Stem Cell 2007;25(9):2350–7. applications in heart failure modeling and repair. Circulation 2017;135(19): [298] Chung HJ, Kim JT, Kim HJ, Kyung HW, Katila P, Lee JH, et al. Epicardial delivery 1832–47. of VEGF and cardiac stem cells guided by 3-dimensional PLLA mat enhancing [276] Weinberger F, Breckwoldt K, Pecha S, Kelly A, Geertz B, Starbatty J, et al. Cardiac cardiac regeneration and angiogenesis in acute myocardial infarction. J Contr repair in Guinea pigs with human engineered heart tissue from induced Release 2015;205:218–30. pluripotent stem cells. Sci Transl Med 2016;8(363):363ra148. [299] Gu X, Matsumura Y, Tang Y, Roy S, Hoff R, Wang B, et al. Sustained viral gene [277] Mohamed TMA, Ang YS, Radzinsky E, Zhou P, Huang Y, Elfenbein A, et al. delivery from a micro-fibrous, elastomeric cardiac patch to the ischemic rat heart. Regulation of cell cycle to stimulate adult cardiomyocyte proliferation and cardiac Biomaterials 2017;133:132–43. regeneration. Cell 2018;173(1):104–116 e112. [300] Shafiq M, Zhang Y, Zhu D, Zhao Z, Kim DH, Kim SH, et al. In situ cardiac [278] Wei K, Serpooshan V, Hurtado C, Diez-Cunado M, Zhao M, Maruyama S, et al. regeneration by using neuropeptide substance P and IGF-1C peptide eluting heart Epicardial FSTL1 reconstitution regenerates the adult mammalian heart. Nature patches. Regen Biomater 2018;5(5):303–16. 2015;525(7570):479–85. [301] Roche ET, Hastings CL, Lewin SA, Shvartsman D, Brudno Y, Vasilyev NV, et al. [279] Meyers TA, Townsend D. Cardiac pathophysiology and the future of cardiac Comparison of biomaterial delivery vehicles for improving acute retention of stem therapies in duchenne muscular dystrophy. Int J Mol Sci 2019;20(17). cells in the infarcted heart. Biomaterials 2014;35(25):6850–8. [280] Duan D. Challenges and opportunities in dystrophin-deficient cardiomyopathy [302] Ruvinov E, Leor J, Cohen S. The promotion of myocardial repair by the sequential gene therapy. Hum Mol Genet 2006;15 Spec(2):R253–61. delivery of IGF-1 and HGF from an injectable alginate biomaterial in a model of [281] Wheeler MT, Allikian MJ, Heydemann A, Hadhazy M, Zarnegar S, McNally EM. acute myocardial infarction. Biomaterials 2011;32(2):565–78. Smooth muscle cell-extrinsic vascular spasm arises from cardiomyocyte [303] Wang LL, Liu Y, Chung JJ, Wang T, Gaffey AC, Lu M, et al. Local and sustained degeneration in sarcoglycan-deficient cardiomyopathy. J Clin Invest 2004;113(5): miRNA delivery from an injectable hydrogel promotes cardiomyocyte 668–75. proliferation and functional regeneration after ischemic injury. Nat Biomed Eng [282] Wheeler MT, Korcarz CE, Collins KA, Lapidos KA, Hack AA, Lyons MR, et al. 2017;1:983–92. Secondary coronary artery vasospasm promotes cardiomyopathy progression. Am [304] Yuan Z, Tsou YH, Zhang XQ, Huang S, Yang Y, Gao M, et al. Injectable citrate- J Pathol 2004;164(3):1063–71. based hydrogel as an angiogenic biomaterial improves cardiac repair after [283] Yasuda S, Townsend D, Michele DE, Favre EG, Day SM, Metzger JM. Dystrophic myocardial infarction. ACS Appl Mater Interfaces 2019;11(42):38429–39. heart failure blocked by membrane sealant poloxamer. Nature 2005;436(7053): 1025–9.

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