Janikiewicz et al. Cell Death and Disease (2018) 9:332 DOI 10.1038/s41419-017-0105-5 Cell Death & Disease

REVIEW ARTICLE Open Access Mitochondria-associated membranes in aging and senescence: structure, function, and dynamics Justyna Janikiewicz1,Jędrzej Szymański1, Dominika Malinska1, Paulina Patalas-Krawczyk1,BernadetaMichalska1, Jerzy Duszyński1, Carlotta Giorgi2, Massimo Bonora3, Agnieszka Dobrzyn1 and Mariusz R. Wieckowski1

Abstract Sites of close contact between mitochondria and the endoplasmic reticulum (ER) are known as mitochondria- associated membranes (MAM) or mitochondria-ER contacts (MERCs), and play an important role in both cell physiology and pathology. A growing body of evidence indicates that changes observed in the molecular composition of MAM and in the number of MERCs predisposes MAM to be considered a dynamic structure. Its involvement in processes such as biosynthesis and trafficking, calcium homeostasis, reactive oxygen species production, and autophagy has been experimentally confirmed. Recently, MAM have also been studied in the context of different pathologies, including Alzheimer's disease, Parkinson’s disease, amyotrophic lateral sclerosis, type 2 diabetes mellitus and GM1-. An underappreciated amount of data links MAM with aging or senescence processes. In the present review, we summarize the current knowledge of basic MAM biology, composition and action, and discuss the potential connections supporting the idea that MAM are significant players in longevity. 1234567890 1234567890 Facts Open questions

● Contacts between mitochondria and the endoplasmic ● Are there any direct or indirect links between aging reticulum not only can be visualized by microscopic and MAM composition, function and dynamics? techniques but can also be isolated in order to ● Which proteins present in the MAM could be investigate their protein and lipid composition. involved in aging or senescence? ● The molecular composition of the mitochondria- ● Does the lipid composition of MAM change during associated membranes (MAM) is closely related to its aging-related processes? role in pivotal cellular processes. ● The involvement of the MAM fraction in numerous Introduction aging-associated pathologies has been confirmed. Aging is a complex phenomenon related to gradual deterioration of cell, tissue, and whole organism functions throughout the lifespan. At the cellular level, aging was found to be associated with oxidative stress, accumulation of DNA modifications, impaired proteostasis, and ineffi- Correspondence: Mariusz R Wieckowski ([email protected]) cient organelle turnover1,2. Not surprisingly, aging affects 1Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland function of individual organelles, including mitochondria 2Department of Morphology, Surgery and Experimental Medicine, Section of and endoplasmic reticulum (ER), and thus, may also have Pathology, Oncology and Experimental Biology, Laboratory for Technologies of impact on their contact sites. These contact sites can be Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy fi Full list of author information is available at the end of the article identi ed as regions of biochemically distinct molecular Justyna Janikiewicz and Jędrzej Szymański contributed equally to this work. Edited by P. Pinton

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composition, which are spatially restricted to the close production, lipid fluxes, autophagy, and regulation of Ca2 + vicinity of the interacting membrane fragments. The turnover in senescence. molecular assemblies forming such link provide a local environment, which can enhance the exchange of cargo or MAM in aging and senescence: a proteomic signals between organelles. Studies conducted in the past perspective decades revealed that mitochondria-associated mem- The MAM proteome was comprehensively analyzed for branes (MAM) form a physical platform enabling com- the first time by Zhang et al.19, who identified 991 pro- munication between the ER and mitochondria, which is teins in the “heavy” MAM fraction (which can be isolated + involved in lipid synthesis, Ca2 trafficking and exchange at lower centrifugal forces compared to standard MAM (See Fig. 1)3. In addition, the proteome of the MAM isolation procedures). Later on, Poston et al.20 reported fraction remains under intensive investigation in the 1212 candidates, including weak soluble proteins, present context of different age-related disorders, such as Alz- at the MAM. Among them were commonly recognized – – heimer's disease4 8, amyotrophic lateral sclerosis9 11, and MAM proteins: ACAT1, BiP/GRP78, calnexin, calreticu- type 2 diabetes mellitus12,13, as well as in obesity14, GM1- lin, Erlin-1, Erlin-2, ERP44, HSPA9, MFN1, PDIA3, gangliosidosis15, and viral infection by human cytomega- VDAC1, VDAC2, and VDAC3. The MS analysis enabled lovirus or hepatitis C virus16,17. Since the function of the characterization and classification of proteins identi- MAM has been better understood, different groups have fied in MAM into three groups: (1) those localized only in tried to investigate their molecular composition and MAM (“MAM-resident proteins”); (2) those localized in reveal which proteins found in MAM are truly transient MAM but present in other cellular compartments or constantly present in MAM, as well as which molecules (“MAM-enriched proteins”); and (3) those temporarily are simply a contamination caused by the imperfectness present in MAM (“MAM-associated proteins”)20.Upto of used cell sub-fractionation protocols. In the present date, increasing number of reports has been published work, we describe close contacts between mitochondria describing importance of the MAM proteome in regula- – and the ER following Giacomello’s and Pellegrini’s ter- tion of cellular biology and senescence17 23. minology, according to which isolated or purified mem- branes (involved in mitochondria-ER interactions) are Mitochondrial structure and MERCs referred to as the “MAM fraction”; however, when the Mitochondrial malfunctioning and structural variations architecture or ultrastructural organization of such con- have been linked with aging and age-associated dis- tacts is discussed, we refer to them as mitochondria-ER orders21,22. Mitochondrial morphology is very dynamic contacts, “MERCs”18. In the present review we focus on and can vary from a fragmented to a filamentous network the MAM proteome and its involvement in ROS as an effect of competition between the processes of

Fig. 1 The historical timeline of the most important experimental observations and key discoveries in the course of studies devoted to interactions between mitochondria and the ER

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fusion and fission, which are the key determinants of the clear that aging process is far too complex to be explained mitochondrial quality control23. In particular, the levels of by one mechanism, the evidence that accumulation of mitochondrial fusion proteins Mfn1 and Mfn2 were oxidative damage is among the events contributing to shown to be increased in aging skeletal muscle, indicating aging phenomenon is quite extensive. Proteins respon- for upregulated fusion, likely in response to the accu- sible for intracellular ROS generation are located nearly in mulated mutations in the mitochondrial DNA24,25. The all subcellular compartments including mitochondria and increased fusion was accompanied by reduced levels of the ER34,35. ROS present at moderate levels participate in the fission protein Fis1. Interestingly, mitochondrial net- intracellular signaling; however, excessive amount of these work rearrangements are regulated by MERCs, which highly reactive molecules is harmful. Since MAM are have been shown to mark the sites of mitochondrial fis- dynamic structures enhancing communication between sion26. Furthermore, senescent human adipose- mitochondria and ER, they may play role in regulation of derived mesenchymal stromal/stem cells exhibited ROS production by ER and mitochondria. increased levels of mitochondrial mass, superoxide and mitochondrial fusion proteins as mitofusin 1 (Mfn1) and ROS sources in mitochondria and ER dynamin-related GTPase (OPA1) compared with Mitochondrial respiratory chain has long been recog- young cells at low passages27. These observations indicate nized as the main source of deleterious free radicals such .•− that changes in mitochondrial morphology observed in as superoxide radical anion (O2 ), which are responsible aging cells can be linked to the misregulated processes of for age-related oxidative stress36,37. In recent years this fission and fusion. view has been challenged and other intracellular ROS sources are gaining increased attention38. Depending on Misfolded protein aggregates present in MERCs the tissue type, physiological state or pathological condi- The loss of proteostasis, which is manifested by the tions, various enzymes localized in different subcellular decreased protein degradation ability of a cell, is one of the compartments may be the dominant ROS producers. hallmarks of aging. Consequently, aggregates of damaged However, the significance of mitochondrial ROS in the or misfolded proteins accumulate, leading to cell degen- aging process is supported by the marked over- eration, and many pathologies. It has been recently representation of the mitochondrial proteome among the reported that mitochondria are involved in the asymmetric proteins subjected to oxidative damage throughout a segregation of the toxic aggregates during cell division in lifespan39. The main ROS produced in mitochondria is 28–30 •− yeast , which provides a mechanism for rejuvenation superoxide radical anion O2 , which is dismutated to of the bud. In this process, the cellular debris is retained in H2O2. In turn, H2O2 gives rise to highly reactive OH in the older mother cell, while the younger bud is essentially the reaction catalyzed by transition metals. There are free of toxic protein waste. The protein aggregates have several sites in mitochondria where ROS can be formed, been shown to associate with the ER surface and localize at including the respiratory chain complexes I and III. The MERCs, indicating the possible role of MERCs in the rate of superoxide generation by these sites depends protein quality control system28. A similar process was strictly on the redox state of the respiratory chain33. Other •− observed in immortalized human mammary epithelial known mitochondrial ROS sources, releasing either O2 stem-like cells undergoing asymmetric division, where or H2O2, include the following: mitochondrial cyto- newly synthesized mitochondria segregated preferentially chrome b5 reductase40 and monoamine oxidases41 to the daughter cell maintaining stemness properties, (associated with outer mitochondrial membrane), dihy- while daughter cells which received older mitochondria droorotate dehydrogenase42, and glycerol-3-phosphate gave rise to differentiated cells31. Further studies using the dehydrogenase (located at the outer surface of the inner split-GFP system in human RPE1 cells and in yeast mitochondrial membrane)43, electron transfer revealed that cytosolic proteins prone to aggregation are flavoprotein-ubiquinone oxidoreductase (localized on the imported into mitochondria in order to undergo degra- matrix face of the inner mitochondrial membrane), and dation by mitochondrial proteases, such as Pim129. two mitochondrial matrix enzyme complexes: α- This indicates that mitochondria play a role in both seg- ketoglutarate dehydrogenase44,45, and pyruvate dehy- regation and degradation of protein aggregates. drogenase35. Interestingly, most of the abovementioned proteins and protein complexes have been found to be Cooperation of mitochondria, the ER and MAM in ROS increasingly carbonylated during aging and senescence39. production When compared with mitochondria, ROS production in Reactive oxygen species (ROS) and aging the ER is less studied, partly due to the limited choices of Increased intracellular levels of ROS and consequential appropriate tools for measuring the ROS levels in this oxidative damage to proteins, , and DNA have been compartment. In the ER, proteins from the cytochrome – reported in many models of aging32 34. Although it is now P450 family46, NADPH oxidase 4 (Nox4)47, and

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endoplasmic reticulum oxireductin (Ero1)48 are the well- state of PDI and transfers the accepted electrons from PDI 64–66 known ROS producers. Ero1 exists in two isoforms: Ero1- to molecular oxygen, leading to H2O2 synthesis .In – α and Ero1-β49 51. Interestingly, Ero1-Lα binds to the ER addition, Ero1-Lα is crucial in the regulation of calcium membrane especially in regions involved in MAM for- release via MAM and IP3R1. During ER stress, Ero1-Lα + mation, and approximately 75% of Ero1-Lα is localized in oxidizes IP3R1, which potentiates the release of Ca2 the MAM fraction52. There is still missing evidence from the ER49. Next, ERp44 (ER luminal chaperone pro- regarding ROS levels in the ER at different stages of life; tein), which can also be found in MAM, binds to IP3R1, + however, aging appears to be accompanied by increased resulting in the inhibition of Ca2 transfer to mitochon- oxidative damage and the dysfunction of specificER dria at MERCs67. Interestingly, IP3R1 oxidation by Ero1- proteins, such as the ryanodine receptor (RyR)53, the Lα causes the dissociation of ERp44 from IP3R1, thus chaperones protein disulfide isomerase (PDI) and immu- promoting the activation of calcium release via IP3R149,68. noglobulin heavy chain binding protein (BiP)54,55. Proteins present in MAM and involved in ROS gen- eration are presented in Fig. 2. Mitochondria-ER contact sites as modulators of ROS synthesis and targets of oxidative damage P66Shc and its involvement in ROS production and aging The MAM structure facilitates mitochondrial calcium Among the many proteins found in the MAM, the 66- uptake upon its release from the ER by coupling IP3R with kilodalton isoform of the growth factor adapter Shc a voltage-dependent anion channel (VDAC)56. The influx (p66Shc) protein has been reported to stimulate ROS + of Ca2 to the mitochondrial matrix affects multiple synthesis and be tightly connected with the oxidative – aspects of mitochondrial function, such as Krebs cycle challenge, age-derived diseases and the aging process69 71. enzyme activity, ATP synthesis, mitochondrial perme- P66Shc together with p52Shc and p46Shc belongs to the ability transition pore (PTP) opening, the mitochondrial ShcA family, and plays the role of a dominant negative membrane potential and respiration, and in consequence, regulator in the from the growth – mitochondrial ROS production57 61. Mutual dependen- factor receptor via the Ras-mediated signaling72,73. Fur- cies between ER function and mitochondrial ROS thermore, it has been demonstrated that p66Shc knockout production have also been demonstrated upon the aging- mice are less sensitive to oxidative and hypoxic stress and dependent deterioration of RyR function53,59. In the live approximately 30% longer than wild-type animals69. skeletal muscle of aged mice, increased carbonylation and While p66Shc is considered a cytosolic protein, it has cysteine nitrosylation of RyR1 was accompanied by also been found in the following locations: (a) the mito- + channel “leakiness,” reduced Ca2 transients upon electric chondrial matrix74; (b) the mitochondrial intermembrane stimulation of the muscle fibers, increased ROS levels and space70; (c) associated with the OMM from its cytosolic impaired muscle force production. The mitochondrially side71; and finally (d) in the MAM fraction. Exogenous or targeted overexpression of catalase diminished the oxi- endogenous oxidative stress can stimulate the critical dative modifications of RyR59. On the other hand, RyR1 phosphorylation of p66Shc at the Ser36 residue69 and destabilization by rapamycin treatment resulted in enhance its translocation to or association with mito- + increased Ca2 levels in the mitochondrial matrix, a chondria75. The p66Shc is phosphorylated at Ser36, and decreased mitochondrial membrane potential and subsequently isomerized, dephosphorylated, and finally enhanced mitochondrial superoxide production59. Fur- translocated to the mitochondrial intermembrane space thermore, increased mitochondrial lipid peroxidation in (MIMS) and/or the MAM fraction, where it participates – the skeletal muscle of mice with the Y522S mutation in in ROS production70,75 80. The p66Shc catalyzes the 2+ RyR1 was associated with increased Ca leakage through reduction of O2 to H2O2 in the mitochondrial inter- the channel62. Interestingly, mitochondrial damage, as membrane space at the cost of cytochrome c oxidation, well as accompanying muscle dysfunction, could be which appears to be an important step in the induction of diminished by treatment with the antioxidant N-acet- apoptosis through the mitochondrial pathway70. Unfor- ylcysteine, indicating involvement of ROS62. tunately, whether p66Shc is translocated to the MIMS in The translocation and enrichment of the MAM fraction mitochondria70 or binds to the OMM (from the cytosolic with the Ero1-Lα isoform is regulated by the oxidor- side) involved in MAM formation71 remains a matter of eductive status of the ER environment. In fact, hypoxic debate. Yet, regardless in which cellular compartment conditions lead to the complete relocation of Ero1-Lα p66Shc contributes to ROS production81, its participation from MAM52. Ero1-Lα is a FAD-dependent oxidase that in the feedback loop of ROS-induced p66Shc ROS pro- together with PDI plays an essential role in protein fold- duction indicates that p66Shc could be involved in ing63,64. PDI directly interacts with newly synthesized and mammalian lifespan regulation. Thus, by translating oxi- folded proteins and catalyzes disulfide bond formation by dative stress damage into cell death, p66Shc becomes an accepting electrons. In turn, Ero1 restores the oxidized apoptotic inducer shortening the lifespan75. The p66Shc

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Fig. 2 ROS-producing proteins localized in mitochondria, the ER, and MAM. Schematic representation of ER, mitochondria, and MAMs with major mechanism of ROS production and Ca2+ cross-talk. 2OGDH Oxoglutarate dehydrogenase, CYB5R3 NADH:cytochrome b5 reductase, cyt. c cytochrome c, DHODH dihydroorotate dehydrogenase, Ero1 endoplasmic reticulum oxireductin, ETF electron transfer flavoprotein-ubiquinone oxidoreductase, Ero1α endoplasmic reticulum oxidoreductin, GPDH glycerol-3-phosphate dehydrogenase, GRP75 75 kDa -regulated protein, NADH:ubiquinone oxidoreductase (I), CoQH2-cytochrome c reductase (III), IMM inner mitochondrial membrane, IP3R inositol triphosphate receptor, KGDHC α-ketoglutarate dehydrogenase complex, MAO monoamine oxidases A/B, Nox4 NADPH oxidase 4, OMM outer mitochondrial membrane, p66Shc p66Shc protein, PDI protein disulfide isomerase, PDH , VDAC voltage-dependent anion channel mRNA and p66Shc protein were highly expressed in p66Shc is also present in plasma membrane-associated fibroblasts from centenarians compared with fibroblasts membranes (PAM). Interestingly, the level of p66Shc from young and elderly individuals82. In contrast, the changes reciprocally in PAM and MAM, depending on primary cultures of skin fibroblasts derived from newborn the age of the animal71. and 18-month-old mice expressed similar levels of It has been demonstrated that an extracellular agonist- + p66Shc71. However, the expression of p66Shc was sig- stimulated Ca2 uptake by mitochondria in mouse nificantly higher in the liver, heart, lungs, skin, and dia- embryonic fibroblasts (MEFs) is gradually decreased with phragm of adult mice than in newborn littermates69. culture time (see Fig. 3)75. Interestingly, such dependency Higher levels of p66Shc in the MAM isolated from the was not reported in p66Shc-deficient MEFs75. After oxi- + livers of old mice and increased ROS production by crude dative challenge, a reduction in the mitochondrial Ca2 mitochondria (containing MAM) argue in favor of the response and fragmentation of the three-dimensional translocation of p66Shc to the MAM in the cellular mitochondrial network was observed in wild-type MEFs, + response to age-related oxidative stress71,83. Moreover, but only minor changes in the Ca2 response and

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2+ 2+ Fig. 3 Mitochondrial calcium uptake as a function of passage number. Mitochondrial Ca responses ([Ca ]mit) in MEFs during ATP challenge as a function of a passage number. The pseudocolor scale (on the right) indicates the approximate changes of mitochondrial calcium level, where light pink represents low Ca2+ and red high (physiological) Ca2+ levels. Blue dots—represent senescence marker, β-galactosidase activity

– – morphology were detected in p66Shc / cells75. Moreover, as well as the number and structure of MERCs. Indeed, the inhibition of p66Shc phosphorylation at Ser36 with the number of contact sites is a well-known determinant + the use of hispidin, a specific blocker of the PKCβ isoform, of the extent of Ca2 transferred between mitochondria preserved the mitochondrial morphology in wild-type and ER88,89. The mechanism of such regulation relies on MEFs. Similarly, no alterations in the passage-dependent the laws of diffusion, according to which doubling the decrease in mitochondrial calcium were observed in these distance causes a fourfold increase in the travel time cells after treatment with hispidin75. required, thus reducing the efficiency of diffusional transport at larger distances18. Recently, it was demon- MAM, the link between mitochondria and the ER in strated that ultrastructure of the MERCs itself, in parti- + mitochondrial Ca2 uptake in senescent cells cular the thickness of MERCs, is a crucial factor + Studies of a neuronal aging model revealed increased regulating the efficiency of Ca2 transport18. Interestingly, + Ca2 transfer from the ER to mitochondria in long-term knockdown of MCU and inositol 1,4,5-trisphosphate cultured neurons, whereas no functional coupling was receptor type 2 (ITPR2), both involved in the accumula- observed between the ER and mitochondria during tion of calcium in mitochondria, resulted in senescence + short-term culturing84. The increased Ca2 uptake by escape, indicating the role of mitochondrial calcium mitochondria is considered to be responsible for the accumulation in senescence induction90. Similarly, lower downregulation of store-operated calcium entry, which in number of contacts between mitochondria and the ER in turn causes the impaired stability of mushroom spines, senescent human fibroblasts could be also responsible for leading to aging-associated cognitive decline84. The the compromised mitochondrial calcium uptake in + increased ER-mitochondria Ca2 transfer was accom- senescent cells. Notwithstanding this, additional studies panied by the upregulation of the mitochondrial calcium are needed to identify which factors have the highest + uniporter (MCU)85, which suggests the involvement of influence of the regulation of Ca2 fluxes through MERCs + MERCs in the process, since they are hotspots for Ca2 in aging cells. + signaling86,87. Increased Ca2 transfer to mitochondria could serve as a regulatory mechanism to counterbalance MAM and longevity: a lipidomic perspective the loss of mitochondrial potential in aging cells. The Morphological data indicate that MERCs are a critical + proposed mechanism of the Ca2 flux through MERCs platform for direct interorganelle lipid synthesis and rapid involves control over the calcium channel expression level lipid transit91. In fact, MAM formation, integrity and

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functioning depend on tightly regulated lipid species and acyltransferase/sterol O-acyltransferase 1 (ACAT1/ a flexible, yet unique, proteome92. SOAT1), diacylglycerol O-acyltransferase 2 (DGAT2), phosphatidylserine synthases 1 and 2 (PSS1 and PSS2), Structural composition and dynamic role of MAM finally phosphatidylethanolamine N-methyltransferase 2 come of age (PEMT2), fatty-acid CoA ligase 4 (FACL4/ACS4), fatty- In comparison to the bulk of the ER, MAM are char- acid transport protein 4 (FATP4), and stearoyl-CoA – acterized by an increased thickness due to their reinfor- desaturase 1 (SCD1) (See Fig. 4)93 98. cement with cholesterol and . Additionally, Initially, MAM were recognized as domains enriched in MAM are characterized by a different degree of curvature, enzymes of the phospholipid biosynthesis and remodeling phospholipid composition, and degree of unsaturation7. pathway99. Indeed, phosphatidylserine (PS) is synthesized As a consequence, the disruption of MAM integrity and in the ER by the MAM enzymes PSS1 and PSS2. The MAM malfunction are linked to an aberrant newly formed PS is transferred to the outer surface of the and a decreased lifespan. Hence, not surprisingly, MAM mitochondrial inner membrane via MAM, where it is are enriched with several lipid transfer proteins and converted into phosphatidylethanolamine (PE) by phos- biosynthesis enzymes, including acyl-CoA:cholesterol phatidylserine decarboxylase. Subsequently, PE returns to

Fig. 4 Lipid network at the MAMs. The ER-mitochondria contact sites integrate assembly of autophagosomes, synthesis, and trafficking of phospholipids, cholesterol (Chol) and (Cer) by a network of MAM- residing enzymes. AP autophagosome, LC3B microtubule-associated protein 1 light chain 3, CL , PA phosphatidic acid, PS phosphatidylserine, PE phosphatidylethanolamine, PC phosphatidylcholine, Preg pregnolone

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the ER, where PEMT2 mediates the synthesis of phos- (ATG), including ATG5, declines in the of aging phatidylcholine (PC). The serine exchange activity is individuals112. Under starvation, the omegasome marker catalyzed by both enzymes, PSS1 and PSS2, whereas PSS1 DCFP1 (double FYVE domain-containing protein 1), the governs the exchange of choline exclusively91,100. Never- pre-AP marker ATG14, Vps34 and ATG5, proteins that theless, the transfer of PS into mitochondria through are critical for AP formation, relocalize toward the MAM MAM is the rate-limiting step during the generation of fraction111. Disruption of the interaction between ATG14 PE91. and DCFP1 in MAM by the knockdown of Pacs2 and In addition, MAM accommodate enzymes indis- Mfn2 in cells prevented proper AP formation and – pensable for cholesterol biosynthesis101 104. The intra- downstream microtubule-associated protein 1 light chain cellular conversion of free cholesterol to cholesteryl esters 3 (LC3) lipidation113. In agreement with this model, dis- is catalyzed by ACAT1 in order to coordinate the dynamic ruption of MERCs by the ablation of Mfn2 in human equilibrium between membrane-bound and cytoplasm- cancer cell lines inhibits interorganelle lipid transfer and stored cholesterol in a resting state105. However, during a starvation-induced autophagy by halting the PS trafficking stress response, cholesterol import to mitochondria is between the ER and mitochondria-derived APs113. sustained where cytochrome P450 initiates steroidogen- Moreover, the abundance of mitochondria-derived PE esis101. Moreover, the depletion of cholesterol in MAM and PS corresponds to longevity107,114. was found to favor the association between MAM and More recently, a role of lipid rafts in regulating autop- mitochondria and lead to not only a decline in the de hagy induction was defined in primary human and mouse novo synthesis of PS but also an improvement in PE embryo fibroblasts115. The account for synthesis101. paradigmatic constituents116. The GD3 gang- Since the proteome of MAM contains lioside was reported to participate in AP biogenesis and phosphodiesterase (SMase), synthase (CerS), maturation by molecular association with key modulators and dihydroceramide desaturase (DES), a certain pool of of autophagic vacuoles, including LC3-II, PtdIns3P, ceramides is believed to be produced at the aforemen- LAMP1, AMBRA1, and BECN1115,117. Moreover, GD3 tioned contact sites102,103,106. Importantly, due to the was reported to be enriched in ER-mitochondria- proapoptotic character of ceramides in mitochondria, associated membranes118, also upon autophagic stimula- MAM might represent a critical checkpoint for prevent- tion115. In addition, lipid rafts were confirmed at the ing ceramide influx, hence regulating shifts in the cellular MAM location during autophagic sequelae115. Hence, lifespan. aforementioned data favor the hypothesis that MAMs operate as a functional platform for early steps of the AP The commitment of MAM and autophagy to lifespan formation, thus any disturbances in the MAMs action and regulation integrity are potentially transitioned into impaired In order to promote longevity, protection against cell autophagy. damage and death is also mediated through autophagy, with The membrane theory of aging supports the idea that special regards of the macroautophagy class. Macro- lifespan is inversely related to unsaturated membrane PL autophagy (hereafter referred as autophagy) is recognized as content119. Caloric restriction (CR) without malnutrition a catabolic process that degrades and recycles the bulk of is the most effective strategy for inducing autophagy and cytosolic components and organelles in response to cellular the key anti-aging intervention for extending the lifespan stress and bioenergetic demands107,108.Theformationofa of yeast, flies, and mice110. Concordantly, CR results in a double-layered structure known as an autophagosome (AP), decrease in the percentage of n-3 and an increase in the is a mandatory hallmark of autophagy. The AP sequesters percentage of n-6 polyunsaturated fatty acids (PUFA)120, components and then fuses with in order to but the ratio of n-3:n-6 PUFAs decreases with increasing deliver its cargo for degradation by lysosomal proteases and lifespan. Such a decrease in membrane PUFA and a hydrolases109. Basal autophagy levels are indispensable for reduced degree of unsaturation contribute positively to physiological quality control, but the impairment and the aging process by lowering susceptibility to perox- declined efficacy of autophagy have been implicated in idative damage22. Moreover, MAM-enriched SCD1 is a numerous human pathologies and aging110. critical enzyme that regulates the cel- Since the discovery of autophagy, there has been lular ratios of saturated/monounsaturated fatty acids intensive debate regarding the membrane and lipid donor (MUFA), and thus remains fundamental for the structure source, which is necessary for the expansion and of cellular membranes121. The gene expression of DGAT2, maturation of the AP. The membranes of mitochondria, which co-localizes with SCD1 in the ER98, was reported to the ER, golgi apparatus, and PM, and fairly recently, decrease in the skin of aging individuals122. In line with MAM, have been proposed to contribute to AP assem- this notion, the inhibition of SCD1 impaired AP biogen- bly107,111. The abundance of autophagy-related proteins esis and affected AP fusion with lysosomes123,124.

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Diminished SCD1 activity was associated with alterations exhibited diminished binding to MAM and disrupted ER- in the status of cellular membrane PE, PC, PS, and car- mitochondria tethers137. diolipin (CL) accumulation, composition, and satura- In AD pathology, sequential proteolytic cleavage of tion124. Furthermore, MAM-delivered PL are critical amyloid precursor protein (APP) releases toxic amyloid β contributors to ATG protein activation and of autophagy peptides (Aβ)93. MAM were shown to be the major site of sequela initiation109. the Aβ formation, since APPs and the majority of the The depletion of CL and its pathological remodeling γ-secretase localized to the MAM4,139,140, followed by coincide with aging. In turn, these changes affect MAM enlarged ER-mitochondria contact area and increased structure and function107, and CL transfer was proposed MAM functionality5. In fact, upregulation of several to depend on MAM125. Unlike other PLs, CL is found MAM-associated lipid metabolism enzymes, including almost exclusively in the mitochondrial inner membrane, ACAT15, was reported in human AD cortical tissue, 141 where it governs the organization and assembly of APPSwe/Lon mice, and primary neurons exposed to Aβ . respiratory complexes126, as well as is involved in control Genetic or pharmacological blockage of ACAT1 increased of the mitochondrial fission machinery127,128. In eukar- APs formation and diminished amyloidopathy in brains of yotic tissues, CL contains MUFA or di-unsaturated chains young and old transgenic AD mice142. Moreover, sig- with 16–18 carbons107, predisposing CL to be more oxi- nificant elevation of membrane- and autophagic vacuole- dative stress-susceptible. In fact, the CL fatty acids were derived lipid species, including cardiolipin, gangliosides, remodeled from linoleic acid (18:2n-6) to more unsatu- or cholesteryl esters was observed alongside exacerbated rated acids, such as arachidonic (20:4n-6) and doc- Aβ levels in cellular systems, AD mouse models and AD osahexaenoic (22:6n-3), in aged rats129. One of the individuals143,144. Hence, a plethora of evidence points to enzymes involved in CL remodeling is MAM-enriched tightly regulated composition and dynamics of MAM acyl-CoA:lysoCL acyltransferase 1 (ALCAT1), which in lipids as a requirement during autophagy and cellular pathological conditions, remodels CL with acyl-CoAs lifespan, but the underlying molecular mechanisms of enriched in long-chain highly unsaturated fatty acids107. such relationship remain a matter of intense investigation. − − Consequently, ALCAT1 / mice were protected from the onset of age-related diseases, including obesity, type 2 Concluding remarks diabetes and hepatosteatosis107. In the current biological perspective, a direct link between the molecular composition of MAM and aging Time flies: defects in MAM couples to aberrant autophagy remains highly underappreciated and awaits further sci- during entific attention. The following indirect evidence supports Dysregulation of autophagic flux leads to accumulation the assumption that MAM significantly impact cellular of abnormal protein aggregates and deteriorated orga- function and longevity: (a) the cell passage-dependent nelles, which alongside reduced expression of ATG, are gradual decrease in mitochondrial calcium uptake and the commonly observed in aging130. Hence, age is the greatest lower number of MERCs in senescent cells; (b) the risk factor for the development of neurodegenerative association between the abundance of p66Shc protein in disorders such as Parkinson’s disease (PD) or Alzheimer’s MAM and animal lifespan; (c) the importance of MAMs disease (AD)131. in regulation of lipid fluxes and autophagy, and (d) the The PD-related proteins, Parkin, and PTEN-induced enrichment of MAMs with the proteins that are involved novel kinase 1 (PINK1) are involved in mitochondrial in the development of age-related neurological and recycling and sequester damaged mitochondria for metabolic disorders. Whether some of the described autophagic clearance by mitophagy132. Moreover, muta- proteins are truly localized in MAM or their presence in tions in Parkin and PTEN were associated with familiar MAM fraction results from imperfectness of the frac- and sporadic cases of PD130,133 and MAMs were identified tioning techniques remain matter of intense debate. as the prime location for local recruitment of LC3-II and a Nevertheless, targeting MAM structure, function, and membrane source for the mitophagosome134. The dynamics might expand the therapeutic repertoire for α-synuclein (SNCA) is another factor contributing to numerous disease conditions, as well as sustained degeneration of dopaminergic neurons in familiar and longevity. sporadic PD incidents135. The aberrant aggregation of SNCA into oligomers during PD is limited by the Acknowledgements 136 We are deeply indebted to past and present collaborators. This work was chaperone-mediated autophagy . The majority of SNCA supported by the Polish National Science Center grants (UMO-2014/15/B/NZ1/ resides in cytoplasm; however, a subpopulation of SNCA 00490) for M.R.W., (UMO-2013/08/W/NZ1/00687) for J.D., J.S., B.M., and P.P.K., was found in MAM137, and its overexpression increased (UMO-2011/03/B/NZ3/00693 and UMO-2013/10/E/NZ3/00670) for A.D. and 137,138 (UMO-2015/19/D/NZ4/03705) for J.J. C.G. was supported by the Italian the extent of contact sites and MAM activity . Fur- Association for Cancer Research (AIRC) and the Italian Ministry of Health and thermore, PD-associated mutant forms of human SNCA Cariplo.

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Author details 19. Zhang, A. et al. Quantitative proteomic analyses of human cytomegalovirus- 1Department of Biochemistry, Nencki Institute of Experimental Biology, induced restructuring of endoplasmic reticulum-mitochondrial contacts at Warsaw, Poland. 2Department of Morphology, Surgery and Experimental late times of infection. Mol. Cell. Proteom. 10, M111.009936 (2011). Medicine, Section of Pathology, Oncology and Experimental Biology, 20. Poston, C. N., Krishnan, S. C. & Bazemore-Walker, C. R. In-depth proteomic Laboratory for Technologies of Advanced Therapies (LTTA), University of analysis of mammalian mitochondria-associated membranes (MAM). J. Pro- Ferrara, Ferrara, Italy. 3Departments of Cell Biology and Gottesman Institute for teom. 79,219–230 (2013). Stem Cell & Regenerative Medicine Research, Albert Einstein College of 21. Veitia,R.A.,Govindaraju,D.R.,Bottani, S. & Birchler, J. A. Aging: Somatic Medicine, Bronx, NY, USA mutations, epigenetic drift and gene dosage imbalance. Trends Cell Biol. 27, 299–310 (2017). Conflict of interest 22. Gonzalez-Freire, M. et al. Reconsidering the Role of Mitochondria in Aging. J. The authors declare that they have no Conflict of interest. Gerontol. Biol. Sci. Med. Sci. 70,1334–1342 (2015). 23. Bernhardt, D., Muller, M., Reichert, A. S. & Osiewacz, H. D. Simultaneous fi Publisher's note impairment of mitochondrial ssion and fusion reduces mitophagy and Springer Nature remains neutral with regard to jurisdictional claims in shortens replicative lifespan. Sci. Rep. 5,7885(2015). published maps and institutional affiliations. 24. Joseph, A. M. et al. Dysregulation of mitochondrial quality control processes contribute to sarcopenia in a mouse model of premature aging. PLoS ONE 8, e69327 (2013). Received: 27 July 2017 Revised: 26 October 2017 Accepted: 27 October 25. O’Leary,M.F.,Vainshtein,A.,Iqbal,S.,Ostojic,O.&Hood,D.A.Adaptive 2017 plasticity of autophagic proteins to denervation in aging skeletal muscle. Am. J. Physiol. Cell Physiol. 304,C422–C430 (2013). 26. Friedman, J. R. et al. ER tubules mark sites of mitochondrial division. Science 334,358–362 (2011). 27. Stab, B. R. et al. Mitochondrial functional changes characterization in young References and senescent human adipose derived MSCs. Front. Aging Neurosci. 8,299 1. Guillaumet-Adkins, A. et al. Epigenetics and Oxidative Stress in Aging. Oxid. (2016). Med Cell. Longev. 2017, 9175806 (2017). 28. Zhou, C. et al. Organelle-based aggregation and retention of damaged 2. Höhn, A. et al. Happily (n)ever after: Aging in the context of oxidative stress, proteins in asymmetrically dividing cells. Cell 159, 530–542 (2014). – proteostasis loss and cellular senescence. Redox Biol. 11,482 501 (2017). 29. Ruan, L. et al. Cytosolic proteostasis through importing of misfolded proteins ń 3. Szyma ski J. et al. Interaction of mitochondria with the endoplasmic reti- into mitochondria. Nature 543, 443–446 (2017). fi culum and plasma membrane in calcium homeostasis, lipid traf cking and 30. Mogk, A. & Bukau, B. Mitochondria tether protein trash to rejuvenate cellular mitochondrial structure. Int. J. Mol. Sci. 18, https://doi.org/10.3390/ environments. Cell 159,471–472 (2014). ijms18071576 (2017). 31. Katajisto, P. et al. Stem cells. Asymmetric apportioning of aged mitochondria 4. Area-Gomez, E. et al. Presenilins are enriched in endoplasmic reticulum between daughter cells is required for stemness. Science 348,340–343 – membranes associated with mitochondria. Am.J.Pathol.175,181016 (2015). (2009). 32. Barja,G.Themitochondrial free radical theory of aging. Prog. Mol. Biol. Transl. 5. Area-Gomez, E. et al. Upregulated function of mitochondria-associated {ER} Sci. 127,1–27 (2014). – membranes in Alzheimer disease. Embo. J. 31,4106 4123 (2012). 33. Brand, M. D., Orr, A. L., Perevoshchikova, I. V.&Quinlan, C. L. The role of 6. Tambini, M. D. et al. ApoE4 upregulates the activity of mitochondria- mitochondrial function and cellular bioenergetics in ageing and disease. Br. J. – associated ER membranes. Embo. Rep. 17,27 36 (2016). Dermatol. 169Suppl 2, 1–8 (2013). 7. Area-Gomez, E. & Schon, E. A. Mitochondria-associated ER membranes and 34. Rinnerthaler,M.,Bischof,J.,Streubel,M.K.,Trost,A.&Richter,K.Oxidative – Alzheimer disease. Curr. Opin. Genet. Dev. 38,90 96 (2016). stress in aging human skin. Biomolecules 5,545–589 (2015). ’ 8. Area-Gomez, E. & Schon, E. A. On the pathogenesis of Alzheimer sDisease: 35. Holmstrom, K. M. & Finkel, T. Cellular mechanisms and physiological con- – The MAM hypothesis. FASEB J. 31, 864 867 (2017). sequences of redox-dependent signalling. Nat. Rev. Mol. Cell. Biol. 15, 9. Watanabe,S.etal.Mitochondria-associated membrane collapse is a com- 411–421 (2014). mon pathomechanism in SIGMAR1- and SOD1-linked ALS. EMBO Mol. Med. 36. Grivennikova, V. G. & Vinogradov, A. D. Mitochondrial production of reactive – 8, 1421 1437 (2016). oxygen species. Biochem. Biokhimiia 78,1490–1511 (2013). 10. Stoica, R. et al. ER-mitochondria associations are regulated by the VAPB- 37.Wojtala,A.etal.Methodsto monitor ROS production by fluorescence PTPIP51 interaction and are disrupted by ALS/FTD-associated TDP-43. Nat. microscopy and fluorometry. Methods Enzymol. 542,243–262 (2014). Commun. 5, 3996 (2014). 38. Brown, G. C. & Borutaite, V. There is no evidence that mitochondria are the 11. Stoica, R. et al. ALS/FTD-associated FUS activates GSK-3beta to disrupt the main source of reactive oxygen species in mammalian cells. Mitochondrion VAPB-PTPIP51 interaction and ER-mitochondria associations. Embo. Rep. 17, 12,1–4(2012). – 1326 1342 (2016). 39. Cabiscol, E., Tamarit, J. & Ros, J. Protein carbonylation: proteomics, specificity 12. Tubbs, E. & Rieusset, J. Metabolic signaling functions of ER-mitochondria and relevance to aging. Mass Spectrom. Rev. 33,21–48 (2014). – contact sites: role in metabolic diseases. Soc. Endocrinol. 1,1 55 (2016). 40. Nishino, H. & Ito, A. Subcellular distribution of OM cytochrome b-mediated 13. Tubbs,E.etal.Mitochondria-associated endoplasmic reticulum membrane NADH-semidehydroascorbate reductase activity in rat liver. J. Biochem. 100, (MAM) integrity is required for insulin signaling and is implicated in hepatic 1523–1531 (1986). – insulin resistance. Diabetes 63, 3279 3294 (2014). 41. Kunduzova, O. R., Bianchi, P., Parini, A. & Cambon, C. Hydrogen peroxide 14. Arruda, A. P. et al. Chronic enrichment of hepatic endoplasmic reticulum- production by monoamine oxidase during ischemia/reperfusion. Eur. J. mitochondria contact leads to mitochondrial dysfunction in obesity. Nat. Pharmacol. 448,225–230 (2002). – Med. 20,1427 1435 (2014). 42. Forman, H. J. & Kennedy, J. Superoxide production and electron transport in 15. Sano, R. et al. GM1- accumulation at the mitochondria-associated mitochondrial oxidation of dihydroorotic acid. J. Biol. Chem. 250,4322–4326 ER membranes links ER stress to Ca(2+)-dependent mitochondrial apoptosis. (1975). – Mol. Cell 36,500 511 (2009). 43. Mracek,T.,Pecinova,A.,Vrbacky,M.,Drahota,Z.&Houstek,J.Highefficiency 16. Williamson, C. D. & Colberg-Poley, A. M. Access of viral proteins to mito- of ROS production by glycerophosphate dehydrogenase in mammalian chondria via mitochondria-associated membranes. Rev. Med. Virol. 19, mitochondria. Arch. Biochem. Biophys. 481,30–36 (2009). – 147 164 (2009). 44. Tretter, L. & Adam-Vizi, V. Generation of reactive oxygen species in the 17.Horner,S.M.,Liu,H.M.,Park,H.S.,Briley,J.&Gale,M.Mitochondrial- reaction catalyzed by alpha-ketoglutarate dehydrogenase. J. Neurosci. 24, associated endoplasmic reticulum membranes (MAM) form innate immune 7771–7778 (2004). synapses and are targeted by hepatitis C virus. Proc. Natl Acad. Sci. USA 108, 45. Starkov, A. A. et al. Mitochondrial alpha-ketoglutarate dehydrogenase com- – 14590 14595 (2011). plex generates reactive oxygen species. J. Neurosci. 24,7779–7788 (2004). 18. Giacomello, M. & Pellegrini, L. The coming of age of the mitochondria-ER contact: a matter of thickness. Cell Death Differ. 23, 1417–1427 (2016).

Official journal of the Cell Death Differentiation Association Janikiewicz et al. Cell Death and Disease (2018) 9:332 Page 11 of 12

46. Bhattacharyya, S., Sinha, K. & Sil, P. C. Cytochrome P450s: mechanisms and 73. Migliaccio, E. et al. Opposite effects of the p52shc/p46shc and p66shc spli- biological implications in drug metabolism and its interaction with oxidative cing isoforms on the EGF receptor-MAP kinase-fos signalling pathway. Embo. stress. Curr. Drug Metab. 15,719–742 (2014). J. 16, 706–716 (1997). 47. Chen, K., Kirber, M. T., Xiao, H., Yang, Y. & Keaney, J. F. Regulation of ROS signal 74. Orsini, F. et al. The life span determinant p66Shc localizes to mitochondria transduction by NADPH oxidase 4 localization. J. Cell Biol. 181, 1129–1139 where it associates with mitochondrial heat shock protein 70 and regulates (2008). trans-membrane potential. J. Biol. Chem. 279, 25689–25695 (2004). 48. Zito, E. ERO1: A protein disulfide oxidase and H2O2 producer. Free Radic. Biol. 75. Pinton, P. et al. Protein kinase C beta and prolyl isomerase 1 regulate Med. 83,299–304 (2015). mitochondrial effects of the life-span determinant p66Shc. Science 315, 49. Anelli, T. et al. Ero1α regulates Ca(2+) fluxes at the endoplasmic reticulum- 659–663 (2007). mitochondria interface (MAM). Antioxid. Redox Signal. 16,1077–1087 (2012). 76. Lebiedzinska, M. et al. Oxidative stress-dependent p66Shc phosphorylation in 50. Raturi, A. & Simmen, T. Where the endoplasmic reticulum and the mito- skin fibroblasts of children with mitochondrial disorders. Biochim. Biophys. chondrion tie the knot: The mitochondria-associated membrane (MAM). Acta 1797,952–960 (2010). Biochim. Biophys. Acta - Mol. Cell Res. 2013,213–224 (1833). 77. Lebiedzinska, M. et al. Disrupted ATP synthase activity and mitochondrial 51. Enyedi, B., Varnai, P. & Geiszt, M. Redox state of the endoplasmic reticulum is hyperpolarisation-dependent oxidative stress is associated with p66Shc controlled by Ero1L-alpha and intraluminal calcium. Antioxid. Redox Signal. phosphorylation in fibroblasts of NARP patients. Int. J. Biochem. Cell Biol. 45, 13,721–729 (2010). 141–150 (2013). 52. Gilady, S. Y. et al. Ero1alpha requires oxidizing and normoxic conditions to 78. Le,S.,Connors,T.J.&Maroney,A.C.c-JunN-terminalkinasespecifically localize to the mitochondria-associated membrane (MAM). Cell Stress Cha- phosphorylates p66ShcA at serine 36 in response to ultraviolet irradiation. J. peron. 15, 619–629 (2010). Biol. Chem. 276,48332–48336 (2001). 53. Andersson, D. C. et al. Ryanodine receptor oxidation causes intracellular 79. Hu, Y. et al. ERK phosphorylates p66shcA on Ser36 and subsequently reg- calcium leak and muscle weakness in aging. Cell Metab. 14,196–207 (2011). ulates p27kip1 expression via the Akt-FOXO3a pathway: implication of 54.Rabek,J.P.,Boylston,W.H.&Papaconstantinou,J.CarbonylationofER p27kip1 in cell response to oxidative stress. Mol. Biol. Cell. 16,3705–3718 chaperone proteins in aged mouse liver. Biochem. Biophys. Res. Commun. (2005). 305,566–572 (2003). 80. Li,M.,Chiou,K.-R.&Kass,D.A.Shearstress inhibition of H(2)O(2) inducedp66 55. Nuss, J. E., Choksi, K. B., DeFord, J. H. & Papaconstantinou, J. Decreased (Shc) phosphorylation by ASK1-JNK inactivation in endothelium. Heart Vessels enzyme activities of chaperones PDI and BiP in aged mouse livers. Biochem. 22,423–427 (2007). Biophys. Res. Commun. 365,355–361 (2008). 81. Mancuso, M. et al. Diagnostic approach to mitochondrial disorders: the need 56. Szabadkai, G. et al. Chaperone-mediated coupling of endoplasmic reticulum for a reliable biomarker. Curr. Mol. Med. 9,1095–1107 (2009). and mitochondrial Ca2+ channels. J. Cell Biol. 175, 901–911 (2006). 82. Pandolfi, S. et al. p66(shc) is highly expressed in fibroblasts from centenarians. 57. Gunter, T. E., Yule, D. I., Gunter, K. K., Eliseev, R. A. & Salter, J. D. Calcium and Mech. Ageing Dev. 126, 839–844 (2005). mitochondria. FEBS Lett. 567,96–102 (2004). 83. Sohal,R.S.&Weindruch,R.Oxidativestress, caloric restriction, and aging. 58. Malinska, D. et al. Complex III-dependent superoxide production of brain Science 273,59–63 (1996). mitochondria contributes to seizure-related ROS formation. Biochim. Biophys. 84. Calvo-Rodriguez, M., Garcia-Durillo, M., Villalobos, C. & Nunez, L. In vitro aging Acta 1797,1163–1170 (2010). promotes endoplasmic reticulum (ER)-mitochondria Ca(2+) cross talk and 59. Hou, T. et al. Synergistic triggering of superoxide flashes by mitochondrial loss of store-operated Ca(2+) entry (SOCE) in rat hippocampal neurons. Ca2+ uniport and basal reactive oxygen species elevation. J. Biol. Chem. 288, Biochim. Biophys. Acta 1863, 2637–2649 (2016). 4602–4612 (2013). 85. Marchi, S. & Pinton, P. The mitochondrial calcium uniporter complex: 60. Bonora, M. et al. Mitochondrial permeability transition involves dissociation of molecular components, structure and physiopathological implications. J. F1FO ATP synthase dimers and C-ring conformation. Embo. Rep. 18, Physiol. 592,829–839 (2014). 1077–1089 (2017). 86. Krols,M.,Bultynck,G.&Janssens,S.ER-Mitochondriacontactsites:Anewreg- 61. Bonora, M. et al. Role of the c subunit of the F O ATP synthase in mito- ulator of cellular calcium fluxcomesintoplay.J. Cell Biol. 214,367–370 (2016). chondrial permeability transition. Cell Cycle 12,674–683 (2014). 87. Danese, A. et al. Calcium regulates cell death in cancer: Roles of the mito- 62. Durham, W. J. et al. RyR1 S-nitrosylation underlies environmental heat stroke chondria and mitochondria-associated membranes (MAMs). Biochim. Bio- and sudden death in Y522S RyR1 knockin mice. Cell 133,53–65 (2008). phys. Acta 1858, 615–627 (2017). 63. Cabibbo, A. et al. ERO1-L, a human protein that favors disulfide bond for- 88. Szabadkai,G.etal.Mitochondrial dynamics and Ca2+ signaling. Biochim. mation in the endoplasmic reticulum. J. Biol. Chem. 275,4827–4833 (2000). Biophys. Acta 1763,442–449 (2006). 64. Ellgaard, L. & Ruddock, L. W. The human protein disulphide isomerase family: 89. Patergnani, S. et al. Calcium signaling around mitochondria associated substrate interactions and functional properties. Embo. Rep. 6,28–32 (2005). membranes (MAMs). Cell Commun. Signal.: CCS 9, 19 (2011). 65. Tu, B. P., Ho-Schleyer, S. C., Travers, K. J. & Weissman, J. S. Biochemical basis of 90. Wiel, C. et al. Endoplasmic reticulum calcium release through ITPR2 channels oxidative protein folding in the endoplasmic reticulum. Science 290, leads to mitochondrial calcium accumulation and senescence. Nat. Com- 1571–1574 (2000). mun. 5, 3792 (2014). 66. Hatahet, F. & Ruddock, L. W. Protein disulfide isomerase: a critical evaluation 91. Vance, J. E. Biochimica et Biophysica Acta MAM (mitochondria-associated of its function in disulfide bond formation. Antioxid. Redox Signal. 11, membranes) in mammalian cells : Lipids and beyond. BBA - Mol. Cell Biol. 2807–2850 (2009). Lipids 1841,595–609 (2014). 67. Higo, T. et al. Subtype-specific and ER lumenal environment-dependent 92. van Vliet, A. R., Verfaillie, T. & Agostinis, P. New functions of mitochondria regulation of inositol 1,4,5-trisphosphatereceptortype1byERp44.Cell 120, associated membranes in cellular signaling. Biochim. Biophys. Acta - Mol. Cell 85–98 (2005). Res. 1843,2253–2262 (2014). 68. Li, G. et al. Role of ERO1-alpha-mediated stimulation of inositol 1,4,5-tri- 93. Schon, E. A. & Area-Gomez, E. Mitochondria-associated ER membranes in phosphate receptor activity in endoplasmic reticulum stress-induced apop- Alzheimer disease. Mol. Cell. Neurosci. 55,26–36 (2013). tosis. J. Cell Biol. 186,783–792 (2009). 94. Rusinol,A.E.,Cui,Z.,Chen,M.H.&Vance,J.E.Auniquemitochondria- 69. Migliaccio, E. et al. The p66shc adaptor protein controls oxidative stress associated membrane fraction from rat liver has a high capacity for lipid response and life span in mammals. Nature 402, 309–313 (1999). synthesis and contains pre-Golgi secretory proteins including nascent lipo- 70. Giorgio, M. et al. Electron transfer between cytochrome c and p66Shc proteins. J. Biol. Chem. 269, 27494–27502 (1994). generates reactive oxygen species that trigger mitochondrial apoptosis. Cell 95. Stone,S.J.etal.Theendoplasmicreticulum enzyme DGAT2 is found in 122,221–233 (2005). mitochondria-associated membranes and has a mitochondrial targeting 71. Lebiedzinska,M.,Duszynski,J.,Rizzuto,R.,Pinton,P.&Wieckowski,M.R.Age- signal that promotes its association with mitochondria. J. Biol. Chem. 284, related changes in levels of p66Shc and serine 36-phosphorylated p66Shc in 5352–5361 (2009). organs and mouse tissues. Arch. Biochem. Biophys. 486,73–80 (2009). 96. Cui,Z.,Vance,J.E.,Chen,M.H.,Voelker,D.R.&Vance,D.E.Cloningand 72. Okada, S. et al. The 66-kDa Shc isoform is a negative regulator of the expression of a novel phosphatidylethanolamine N-methyltransferase—a epidermal growth factor-stimulated mitogen-activated protein kinase path- specific biochemical and cytological marker for a unique membrane-fraction way. J. Biol. Chem. 272, 28042–28049 (1997). in rat-liver. J. Biol. Chem. 268, 16655–16663 (1993).

Official journal of the Cell Death Differentiation Association Janikiewicz et al. Cell Death and Disease (2018) 9:332 Page 12 of 12

97. Lewin, T. M., Van Horn, C. G., Krisans, S. K. & Coleman, R. A. Rat liver acyl-CoA membrane peroxidizability in rat liver mitochondria. Mech. Ageing Dev. 125, synthetase 4 is a peripheral-membrane protein located in two distinct 529–538 (2004). subcellular organelles, peroxisomes, and mitochondrial-associated mem- 121. Dobrzyn, P., Jazurek, M. & Dobrzyn, A. Stearoyl-CoA desaturase and insulin brane. Arch. Biochem. Biophys. 404,263–270 (2002). signaling–what is the molecular switch? Biochim. Biophys. Acta 1797, 98. Man,W.C.,Miyazaki,M.,Chu,K.&Ntambi, J. Colocalization of SCD1 and 1189–1194 (2010). DGAT2: implying preference for endogenous monounsaturated fatty acids in 122. MitchellW.D.,ThompsonT.L.Psychiatric distress in systemic lupus erythe- triglyceride synthesis. J. Lipid Res. 47,1928–1939 (2006). matosus outpatients. Psychosomatics 31: 293–300 (1990). 99. Vance, J. E. Phospholipid synthesis in a membrane fraction associated with 123. Ogasawara, Y. et al. Stearoyl-CoA desaturase 1 activity is required for mitochondria. J. Biol. Chem. 265, 7248–7256 (1990). autophagosome formation. J. Biol. Chem. 289,23938–23950 (2014). 100. Naon, D. & Scorrano, L. At the right distance: ER-mitochondria juxtapo- 124. Janikiewicz, J. et al. Inhibition of SCD1 impairs palmitate-derived autophagy sition in cell life and death. Biochim. Biophys. Acta - Mol. Cell Res. 1843, at the step of autophagosome- fusion in pancreatic β-cells. J. Lipid 2184–2194 (2014). Res. 56, 1901–1911 (2015). 101. Fujimoto, M., Hayashi, T. & Su, T. P. The role of cholesterol in the association of 125. Giorgi, C. et al. Mitochondria-associated membranes: composition, molecular endoplasmic reticulum membranes with mitochondria. Biochem. Biophys. mechanisms, and physiopathological implications. Antioxid. Redox Signal. 22, Res. Commun. 417,635–639 (2012). 995–1019 (2015). 102. Wu,B.X.,Rajagopalan,V.,Roddy,P.L.,Clarke,C.J.&Hannun,Y.A.Identifi- 126. Monteiro,J.P.,Oliveira,P.J.&Jurado,A.S.Mitochondrialmembranelipid cation and characterization of murine mitochondria-associated neutral remodeling in pathophysiology: a new target for diet and therapeutic sphingomyelinase (MA-nSMase), the mammalian sphingomyelin phospho- interventions. Prog. Lipid Res. 52,513–528 (2013). diesterase 5. J. Biol. Chem. 285, 17993–18002 (2010). 127. Adachi, Y. et al. Coincident phosphatidic acid interaction restrains Drp1 in 103. Bionda,C.,Portoukalian,J.,Schmitt,D.,Rodriguez-Lafrasse,C.&Ardail,D. mitochondrial division. Mol. Cell 63,1034–1043 (2016). Subcellular compartmentalization of ceramide metabolism: MAM (mito- 128. Stepanyants, N. et al. Cardiolipin’s propensity for phase transition and its chondria-associated membrane) and/or mitochondria? Biochem. J. 382, reorganization by dynamin-related protein 1 form a basis for mitochondrial 527–533 (2004). membrane fission. Mol. Biol. Cell. 26,3104–3116 (2015). 104. Issop, L. et al. Mitochondria-associated membrane formation in - 129. Lee,H.J.,Mayette,J.,Rapoport,S.I.&Bazinet,R.P.Selectiveremodelingof stimulated leydig cell steroidogenesis: Role of ATAD3. Endocrinology 156, cardiolipin fatty acids in the aged rat heart. Lipids Health Dis. 5, 2 (2006). 334–345 (2015). 130. Banerjee,R.,Beal,M.F.&Thomas,B.Autophagyinneurodegenerativedis- 105. Puglielli, L. et al. Acyl-coenzyme A: cholesterol acyltransferase modulates orders: pathogenic roles and therapeutic implications. Trends Neurosci. 33, the generation of the amyloid beta-peptide. Nat. Cell Biol. 3,905–912 541–549 (2010). (2001). 131. Krols, M. et al. Mitochondria-associated membranes as hubs for neurode- 106. Stiban,J.,Caputo,L.&Colombini,M.Ceramidesynthesisintheendoplasmic generation. Acta Neuropathol. (Berl.) 131,505–523 (2016). reticulum can permeabilize mitochondria to proapoptotic proteins. J. Lipid 132. Eiyama, A. & Okamoto, K. PINK1/Parkin-mediated mitophagy in mammalian Res. 49, 625–634 (2008). cells. Curr. Opin. Cell Biol. 33,95–101 (2015). 107. Hsu, P. & Shi, Y. Regulation of autophagy by mitochondrial phospholipids in 133. Deas,E.,Wood,N.W.&Plun-Favreau,H.MitophagyandParkinson’sdisease: health and diseases. Biochim. Biophys. Acta 1862,114–129 (2017). the PINK1-parkin link. Biochim. Biophys. Acta 1813, 623–633 (2011). 108. Green, D. R., Galluzzi, L. & Kroemer, G. Mitochondria and the autophagy- 134. Yang, J. -Y. & Yang, W. Y. Bit-by-bit autophagic removal of parkin-labelled inflammation-cell death axis in organismal aging. Science 333, mitochondria. Nat. Commun. 4, 2428 (2013). 1109–1112 (2011). 135. Rodríguez-Arribas M. et al. Mitochondria-associated membranes (MAMs): 109. Janikiewicz, J., Hanzelka, K., Kozinski, K., Kolczynska,K.&Dobrzyn,A.Isletbeta- Overview and its role in Parkinson’sdisease.Mol. Neurobiol.https://doi.org/ cell failure in type 2 diabetes–Within the network of toxic lipids. Biochem. 10.1007/s12035-016-0140-8 (2016). Biophys. Res. Commun. 460,491–496 (2015). 136. Cuervo,A.M.,Stefanis,L.,Fredenburg,R.,Lansbury,P.T.&Sulzer,D.Impaired 110. Rubinsztein, D. C., Marino, G. & Kroemer, G. Autophagy and aging. Cell 146, degradation of mutant alpha-synuclein by chaperone-mediated autophagy. 682–695 (2011). Science 305, 1292–1295 (2004). 111. Hamasaki, M. et al. Autophagosomes form at ER-mitochondria contact sites. 137. Guardia-Laguarta, C., Area-Gomez, E., Schon, E. A. & Przedborski, S. Novel Nature 495,389–393 (2013). subcellular localization for α-synuclein: possible functional consequences. 112. Lipinski,M.M.etal.Genome-wideanalysis reveals mechanisms modulating Front. Neuroanat. 9, 17 (2015). autophagy in normal brain aging and in Alzheimer’sdisease.Proc. Natl Acad. 138. Calì, T., Ottolini, D., Negro, A. & Brini, M. α-Synuclein controls mitochondrial Sci. USA 107, 14164–14169 (2010). calcium homeostasis by enhancing endoplasmic reticulum-mitochondria 113. Hailey, D. W. et al. Mitochondria supply membranes for autophagosome interactions. J. Biol. Chem. 287,17914–17929 (2012). biogenesis during starvation. Cell 141,656–667 (2010). 139. Schreiner, B., Hedskog, L., Wiehager, B. & Ankarcrona, M. Amyloid-β peptides 114. Rockenfeller, P. et al. Phosphatidylethanolamine positively regulates autop- are generated in mitochondria-associated endoplasmic reticulum mem- hagy and longevity. Cell Death Differ. 22,499–508 (2015). branes. J. Alzheimers Dis. JAD 43,369–374 (2015). 115. Garofalo, T. et al. Evidence for the involvement of lipid rafts localized at the 140. Del Prete, D. et al. Localization and processing of the amyloid-β protein ER-mitochondria associated membranes in autophagosome formation. precursor in mitochondria-associated membranes. J. Alzheimers Dis. JAD 55, Autophagy 12,917–935 (2016). 1549–1570 (2017). 116. Sonnino, S. & Prinetti, A. Membrane domains and the ‘lipid raft’ concept. Curr. 141. Hedskog, L. et al. Modulation of the endoplasmic reticulum-mitochondria Med. Chem. 20,4–21 (2013). interface in Alzheimer’s disease and related models. Proc. Natl Acad. Sci. USA 117. Matarrese, P. et al. Evidence for the involvement of GD3 ganglioside in 110, 7916–7921 (2013). autophagosome formation and maturation. Autophagy 10,750–765 (2014). 142. Shibuya, Y. et al. Acyl-coenzyme A:cholesterol acyltransferase1blockage 118. Mattei, V. et al. Recruitment of cellular prion protein to mitochondrial raft-like enhances autophagy in the neurons of triple transgenic Alzheimer’sdisease microdomains contributes to apoptosis execution. Mol. Biol. Cell 22, mouse and reduces human P301L-tau content at the presymptomatic stage. 4842–4853 (2011). Neurobiol. Aging 36,2248–2259 (2015). 119. Pamplona, R., Barja, G. & Portero-Otin, M. Membrane fatty acid unsaturation, 143. Chan, R. B. et al. Comparative lipidomic analysis of mouse and human brain protection against oxidative stress, and maximum life span: a homeoviscous- with Alzheimer disease. J. Biol. Chem. 287,2678–2688 (2012). longevity adaptation? Ann. N. Acad. Sci. 959,475–490 (2002). 144. Yang D. -S, et al.Defective macroautophagic turnover of brain lipids in the 120. Lambert,A.J.,Portero-Otin,M.,Pamplona,R.&Merry,B.J.Effectofageing TgCRND8 Alzheimer mouse model: prevention by correcting lysosomal and caloric restriction on specific markers of protein oxidative damage and proteolytic deficits. Brain J. Neurol.137,3300–3318 (2014).

Official journal of the Cell Death Differentiation Association