HIV-1: to Splice Or Not to Splice, That Is the Question
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An Exonic Splicing Silencer Is Involved in the Regulated Splicing of Glucose 6-Phosphate Dehydrogenase Mrna Wioletta Szeszel-Fedorowicz
Faculty Scholarship 2006 An Exonic Splicing Silencer Is Involved In The Regulated Splicing Of Glucose 6-Phosphate Dehydrogenase Mrna Wioletta Szeszel-Fedorowicz Indrani Talukdar Brian N. Griffith Callee M. Walsh Lisa M. Salati Follow this and additional works at: https://researchrepository.wvu.edu/faculty_publications Digital Commons Citation Szeszel-Fedorowicz, Wioletta; Talukdar, Indrani; Griffith,r B ian N.; Walsh, Callee M.; and Salati, Lisa M., "An Exonic Splicing Silencer Is Involved In The Regulated Splicing Of Glucose 6-Phosphate Dehydrogenase Mrna" (2006). Faculty Scholarship. 464. https://researchrepository.wvu.edu/faculty_publications/464 This Article is brought to you for free and open access by The Research Repository @ WVU. It has been accepted for inclusion in Faculty Scholarship by an authorized administrator of The Research Repository @ WVU. For more information, please contact [email protected]. THE JOURNAL OF BIOLOGICAL CHEMISTRY VOL. 281, NO. 45, pp. 34146–34158, November 10, 2006 © 2006 by The American Society for Biochemistry and Molecular Biology, Inc. Printed in the U.S.A. An Exonic Splicing Silencer Is Involved in the Regulated Splicing of Glucose 6-Phosphate Dehydrogenase mRNA* Received for publication, April 20, 2006, and in revised form, September 14, 2006 Published, JBC Papers in Press, September 15, 2006, DOI 10.1074/jbc.M603825200 Wioletta Szeszel-Fedorowicz, Indrani Talukdar, Brian N. Griffith, Callee M. Walsh, and Lisa M. Salati1 From the Department of Biochemistry and Molecular Pharmacology, West Virginia University, Morgantown, West Virginia 26506 The inhibition of glucose-6-phosphate dehydrogenase (G6PD) in converting excess dietary energy into a storage form. Con- expression by arachidonic acid occurs by changes in the rate sistent with this role in energy homeostasis, the capacity of this of pre-mRNA splicing. -
Serine Arginine-Rich Protein-Dependent Suppression Of
Serine͞arginine-rich protein-dependent suppression of exon skipping by exonic splicing enhancers El Che´ rif Ibrahim*, Thomas D. Schaal†, Klemens J. Hertel‡, Robin Reed*, and Tom Maniatis†§ *Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115; †Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138; and ‡Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697-4025 Contributed by Tom Maniatis, January 28, 2005 The 5 and 3 splice sites within an intron can, in principle, be joined mechanisms by which exon skipping is prevented. Our data to those within any other intron during pre-mRNA splicing. How- reveal that splicing to the distal 3Ј splice site is suppressed by ever, exons are joined in a strict 5 to 3 linear order in constitu- proximal exonic sequences and that SR proteins are required for tively spliced pre-mRNAs. Thus, specific mechanisms must exist to this suppression. Thus, SR protein͞exonic enhancer complexes prevent the random joining of exons. Here we report that insertion not only function in exon and splice-site recognition but also play of exon sequences into an intron can inhibit splicing to the a role in ensuring that 5Ј and 3Ј splice sites within the same intron .downstream 3 splice site and that this inhibition is independent of are used, thus suppressing exon skipping intron size. The exon sequences required for splicing inhibition were found to be exonic enhancer elements, and their inhibitory Materials and Methods activity requires the binding of serine͞arginine-rich splicing fac- Construction of Plasmids. -
HIV-1 Rev Downregulates Tat Expression and Viral Replication Via Modulation of NAD(P)H:Quinine Oxidoreductase 1 (NQO1)
ARTICLE Received 25 Jul 2014 | Accepted 22 Apr 2015 | Published 10 Jun 2015 DOI: 10.1038/ncomms8244 HIV-1 Rev downregulates Tat expression and viral replication via modulation of NAD(P)H:quinine oxidoreductase 1 (NQO1) Sneh Lata1,*, Amjad Ali2,*, Vikas Sood1,2,w, Rameez Raja2 & Akhil C. Banerjea2 HIV-1 gene expression and replication largely depend on the regulatory proteins Tat and Rev, but it is unclear how the intracellular levels of these viral proteins are regulated after infection. Here we report that HIV-1 Rev causes specific degradation of cytoplasmic Tat, which results in inhibition of HIV-1 replication. The nuclear export signal (NES) region of Rev is crucial for this activity but is not involved in direct interactions with Tat. Rev reduces the levels of ubiquitinated forms of Tat, which have previously been reported to be important for its transcriptional properties. Tat is stabilized in the presence of NAD(P)H:quinine oxidoreductase 1 (NQO1), and potent degradation of Tat is induced by dicoumarol, an NQO1 inhibitor. Furthermore, Rev causes specific reduction in the levels of endogenous NQO1. Thus, we propose that Rev is able to induce degradation of Tat indirectly by downregulating NQO1 levels. Our findings have implications in HIV-1 gene expression and latency. 1 Department of Microbiology, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi 110095, India. 2 Laboratory of Virology, National Institute of Immunology, New Delhi 110067, India. * These authors contributed equally to this work. w Present address: Translational Health Science and Technology Institute, Faridabad, Haryana 121004, India. Correspondence and requests for materials should be addressed to A.C.B. -
In Silico Tools for Splicing Defect Prediction: a Survey from the Viewpoint of End Users
© American College of Medical Genetics and Genomics REVIEW In silico tools for splicing defect prediction: a survey from the viewpoint of end users Xueqiu Jian, MPH1, Eric Boerwinkle, PhD1,2 and Xiaoming Liu, PhD1 RNA splicing is the process during which introns are excised and informaticians in relevant areas who are working on huge data sets exons are spliced. The precise recognition of splicing signals is critical may also benefit from this review. Specifically, we focus on those tools to this process, and mutations affecting splicing comprise a consider- whose primary goal is to predict the impact of mutations within the able proportion of genetic disease etiology. Analysis of RNA samples 5′ and 3′ splicing consensus regions: the algorithms used by different from the patient is the most straightforward and reliable method to tools as well as their major advantages and disadvantages are briefly detect splicing defects. However, currently, the technical limitation introduced; the formats of their input and output are summarized; prohibits its use in routine clinical practice. In silico tools that predict and the interpretation, evaluation, and prospection are also discussed. potential consequences of splicing mutations may be useful in daily Genet Med advance online publication 21 November 2013 diagnostic activities. In this review, we provide medical geneticists with some basic insights into some of the most popular in silico tools Key Words: bioinformatics; end user; in silico prediction tool; for splicing defect prediction, from the viewpoint of end users. Bio- medical genetics; splicing consensus region; splicing mutation INTRODUCTION TO PRE-mRNA SPLICING AND small nuclear ribonucleoproteins and more than 150 proteins, MUTATIONS AFFECTING SPLICING serine/arginine-rich (SR) proteins, heterogeneous nuclear ribo- Sixty years ago, the milestone discovery of the double-helix nucleoproteins, and the regulatory complex (Figure 1). -
Viroporins: Structures and Functions Beyond Cell Membrane Permeabilization
Editorial Viroporins: Structures and Functions beyond Cell Membrane Permeabilization José Luis Nieva 1,* and Luis Carrasco 2,* Received: 17 September 2015 ; Accepted: 21 September 2015 ; Published: 29 September 2015 Academic Editor: Eric O. Freed 1 Biophysics Unit (CSIC, UPV/EHU) and Biochemistry and Molecular Biology Department, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain 2 Centro de Biología Molecular Severo Ochoa (CSIC, UAM), c/Nicolás Cabrera, 1, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain * Correspondence: [email protected] (J.L.N.); [email protected] (L.C.); Tel.: +34-94-601-3353 (J.L.N.); +34-91-497-8450 (L.C.) Viroporins represent an interesting group of viral proteins that exhibit two sets of functions. First, they participate in several viral processes that are necessary for efficient production of virus progeny. Besides, viroporins interfere with a number of cellular functions, thus contributing to viral cytopathogenicity. Twenty years have elapsed from the first review on viroporins [1]; since then several reviews have covered the advances on viroporin structure and functioning [2–8]. This Special Issue updates and revises new emerging roles of viroporins, highlighting their potential use as antiviral targets and in vaccine development. Viroporin structure. Viroporins are usually short proteins with at least one hydrophobic amphipathic helix. Homo-oligomerization is achieved by helix–helix interactions in membranes rendering higher order structures, forming aqueous pores. Progress in viroporin structures during the last 2–3 years has in some instances provided a detailed knowledge of their functional architecture, including the fine definition of binding sites for effective inhibitors. -
Opportunistic Intruders: How Viruses Orchestrate ER Functions to Infect Cells
REVIEWS Opportunistic intruders: how viruses orchestrate ER functions to infect cells Madhu Sudhan Ravindran*, Parikshit Bagchi*, Corey Nathaniel Cunningham and Billy Tsai Abstract | Viruses subvert the functions of their host cells to replicate and form new viral progeny. The endoplasmic reticulum (ER) has been identified as a central organelle that governs the intracellular interplay between viruses and hosts. In this Review, we analyse how viruses from vastly different families converge on this unique intracellular organelle during infection, co‑opting some of the endogenous functions of the ER to promote distinct steps of the viral life cycle from entry and replication to assembly and egress. The ER can act as the common denominator during infection for diverse virus families, thereby providing a shared principle that underlies the apparent complexity of relationships between viruses and host cells. As a plethora of information illuminating the molecular and cellular basis of virus–ER interactions has become available, these insights may lead to the development of crucial therapeutic agents. Morphogenesis Viruses have evolved sophisticated strategies to establish The ER is a membranous system consisting of the The process by which a virus infection. Some viruses bind to cellular receptors and outer nuclear envelope that is contiguous with an intri‑ particle changes its shape and initiate entry, whereas others hijack cellular factors that cate network of tubules and sheets1, which are shaped by structure. disassemble the virus particle to facilitate entry. After resident factors in the ER2–4. The morphology of the ER SEC61 translocation delivering the viral genetic material into the host cell and is highly dynamic and experiences constant structural channel the translation of the viral genes, the resulting proteins rearrangements, enabling the ER to carry out a myriad An endoplasmic reticulum either become part of a new virus particle (or particles) of functions5. -
Position-Dependent Splicing Activation and Repression by SR and Hnrnp Proteins Rely on Common Mechanisms
Position-dependent splicing activation and repression by SR and hnRNP proteins rely on common mechanisms STEFFEN ERKELENZ,1,3 WILLIAM F. MUELLER,2,3 MELANIE S. EVANS,2 ANKE BUSCH,2 KATRIN SCHO¨ NEWEIS,1 KLEMENS J. HERTEL,2,4 and HEINER SCHAAL1,4 1Institute of Virology, Heinrich-Heine-University, D-40225 Du¨sseldorf, Germany 2Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, California 92697-4025, USA ABSTRACT Alternative splicing is regulated by splicing factors that modulate splice site selection. In some cases, however, splicing factors show antagonistic activities by either activating or repressing splicing. Here, we show that these opposing outcomes are based on their binding location relative to regulated 59 splice sites. SR proteins enhance splicing only when they are recruited to the exon. However, they interfere with splicing by simply relocating them to the opposite intronic side of the splice site. hnRNP splicing factors display analogous opposing activities, but in a reversed position dependence. Activation by SR or hnRNP proteins increases splice site recognition at the earliest steps of exon definition, whereas splicing repression promotes the assembly of nonproductive complexes that arrest spliceosome assembly prior to splice site pairing. Thus, SR and hnRNP splicing factors exploit similar mechanisms to positively or negatively influence splice site selection. Keywords: SR protein; hnRNP protein; pre-mRNA splicing; splicing activation; splicing repression INTRODUCTION their RS domain (Fu and Maniatis 1992; Lin and Fu 2007) or through RNA binding domain interactions with U1 Alternative pre-mRNA splicing promotes high proteomic snRNP-specific protein 70K (Cho et al. 2011). However, in diversity despite the limited number of protein coding some cases SR proteins were shown to interfere with exon genes (Nilsen and Graveley 2010). -
Human Retroviruses in the Second Decade: a Personal Perspective
© 1995 Nature Publishing Group http://www.nature.com/naturemedicine • REVIEW Human retroviruses in the second decade: A personal perspective Human retroviruses have developed novel strategies for their propagation and survival. A consequence of their success has been the induction of an extraordinarily diverse set of human dlst!ases, including AIDS, cancers and neurological and Inflammatory disorders. Early research focused on their characterization, linkage to these dlst!ases, and the mechanisms Involved. Research should now aim at the eradication of human retroviruses and on treatment of infected people. Retroviruses are transmitted either geneti- .................... ···.. .... ·. ..... .. discovered". Though its characteristics are cally (endogenous form) or as infectious ROBERT C. GALLO strikingly similar to HTLV-1, HTLV-II is not agents (exogenous form)'·'. As do many so clearly linked to human disease. It is cu other animal species, humans have both forms ..... In general, rious that HTLV-11 is endemic in some American Indians and endogenous retroviruses are evolutionary relics of old infec more prevalent in drug addicts than HTLV-I"·'•. tions and are not known to cause disease. The DNA of many HIV-1 is also most prevalent in equatorial Africa, but in con species, including humans, harbours multiple copies of differ trast to HTLV the demography of the HIV epidemic is still in ent retroviral proviruses. The human endogenous proviral flux, and the virus is new to most of the world. The number of sequences are virtually all defective, and comprise about one infected people worldwide is now estimated to be about 17 mil percent of the human genome, though R. Kurth's group in lion and is predicted to reach 30 to SO million by the year 2000. -
Mechanisms of Action of Novel Influenza A/M2 Viroporin Inhibitors Derived from Hexamethylene Amiloride S
Supplemental material to this article can be found at: http://molpharm.aspetjournals.org/content/suppl/2016/05/18/mol.115.102731.DC1 1521-0111/90/2/80–95$25.00 http://dx.doi.org/10.1124/mol.115.102731 MOLECULAR PHARMACOLOGY Mol Pharmacol 90:80–95, August 2016 Copyright ª 2016 by The American Society for Pharmacology and Experimental Therapeutics Mechanisms of Action of Novel Influenza A/M2 Viroporin Inhibitors Derived from Hexamethylene Amiloride s Pouria H. Jalily, Jodene Eldstrom, Scott C. Miller, Daniel C. Kwan, Sheldon S. -H. Tai, Doug Chou, Masahiro Niikura, Ian Tietjen, and David Fedida Department of Anesthesiology, Pharmacology, and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver (P.H.J., J.E., S.C.M., D.C.K., D.C., I.T., D.F.), and Faculty of Health Sciences, Simon Fraser University, Burnaby (S.S.-H.T., M.N., I.T.), British Columbia, Canada Received December 7, 2015; accepted May 12, 2016 Downloaded from ABSTRACT The increasing prevalence of influenza viruses with resistance to [1,19-biphenyl]-4-carboxylate (27) acts both on adamantane- approved antivirals highlights the need for new anti-influenza sensitive and a resistant M2 variant encoding a serine to asparagine therapeutics. Here we describe the functional properties of hexam- 31 mutation (S31N) with improved efficacy over amantadine and – 5 m m ethylene amiloride (HMA) derived compounds that inhibit the wild- HMA (IC50 0.6 Mand4.4 M, respectively). Whereas 9 inhibited molpharm.aspetjournals.org type and adamantane-resistant forms of the influenza A M2 ion in vitro replication of influenza virus encoding wild-type M2 (EC50 5 channel. -
Determinants of Exon 7 Splicing in the Spinal Muscular Atrophy Genes, SMN1 and SMN2 Luca Cartegni,*,† Michelle L
Determinants of Exon 7 Splicing in the Spinal Muscular Atrophy Genes, SMN1 and SMN2 Luca Cartegni,*,† Michelle L. Hastings,* John A. Calarco,‡ Elisa de Stanchina, and Adrian R. Krainer Cold Spring Harbor Laboratory, Cold Spring Harbor, NY Spinal muscular atrophy is a neurodegenerative disorder caused by the deletion or mutation of the survival-of- motor-neuron gene, SMN1. An SMN1 paralog, SMN2, differs by a CrT transition in exon 7 that causes substantial skipping of this exon, such that SMN2 expresses only low levels of functional protein. A better understanding of SMN splicing mechanisms should facilitate the development of drugs that increase survival motor neuron (SMN) protein levels by improving SMN2 exon 7 inclusion. In addition, exonic mutations that cause defective splicing give rise to many genetic diseases, and the SMN1/2 system is a useful paradigm for understanding exon-identity determinants and alternative-splicing mechanisms. Skipping of SMN2 exon 7 was previously attributed either to the loss of an SF2/ASF–dependent exonic splicing enhancer or to the creation of an hnRNP A/B–dependent exonic splicing silencer, as a result of the CrT transition. We report the extensive testing of the enhancer-loss and silencer- gain models by mutagenesis, RNA interference, overexpression, RNA splicing, and RNA-protein interaction ex- periments. Our results support the enhancer-loss model but also demonstrate that hnRNP A/B proteins antagonize SF2/ASF–dependent ESE activity and promote exon 7 skipping by a mechanism that is independent of the CrT transition and is, therefore, common to both SMN1 and SMN2. Our findings explain the basis of defective SMN2 splicing, illustrate the fine balance between positive and negative determinants of exon identity and alternative splicing, and underscore the importance of antagonistic splicing factors and exonic elements in a disease context. -
Filoviral Immune Evasion Mechanisms
Viruses 2011, 3, 1634-1649; doi:10.3390/v3091634 OPEN ACCESS viruses ISSN 1999-4915 www.mdpi.com/journal/viruses Review Filoviral Immune Evasion Mechanisms Parameshwaran Ramanan 1,3, Reed S. Shabman 2, Craig S. Brown 1,4, Gaya K. Amarasinghe 1,*, Christopher F. Basler 2,* and Daisy W. Leung 1,* 1 Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA 2 Department of Microbiology, Mount Sinai School of Medicine, New York, NY 10029, USA 3 Biochemistry Graduate Program, Iowa State University, Ames, IA 50011, USA 4 Biochemistry Undergraduate Program, Iowa State University, Ames, IA 50011, USA * Authors to whom correspondence should be addressed; [email protected] (G.K.A); [email protected] (C.F.B); [email protected] (D.W.L.). Received: 11 August 2011 / Accepted: 15 August 2011 / Published: 7 September 2011 Abstract: The Filoviridae family of viruses, which includes the genera Ebolavirus (EBOV) and Marburgvirus (MARV), causes severe and often times lethal hemorrhagic fever in humans. Filoviral infections are associated with ineffective innate antiviral responses as a result of virally encoded immune antagonists, which render the host incapable of mounting effective innate or adaptive immune responses. The Type I interferon (IFN) response is critical for establishing an antiviral state in the host cell and subsequent activation of the adaptive immune responses. Several filoviral encoded components target Type I IFN responses, and this innate immune suppression is important for viral replication and pathogenesis. For example, EBOV VP35 inhibits the phosphorylation of IRF-3/7 by the TBK-1/IKKε kinases in addition to sequestering viral RNA from detection by RIG-I like receptors. -
A Novel Ebola Virus VP40 Matrix Protein-Based Screening for Identification of Novel Candidate Medical Countermeasures
viruses Communication A Novel Ebola Virus VP40 Matrix Protein-Based Screening for Identification of Novel Candidate Medical Countermeasures Ryan P. Bennett 1,† , Courtney L. Finch 2,† , Elena N. Postnikova 2 , Ryan A. Stewart 1, Yingyun Cai 2 , Shuiqing Yu 2 , Janie Liang 2, Julie Dyall 2 , Jason D. Salter 1 , Harold C. Smith 1,* and Jens H. Kuhn 2,* 1 OyaGen, Inc., 77 Ridgeland Road, Rochester, NY 14623, USA; [email protected] (R.P.B.); [email protected] (R.A.S.); [email protected] (J.D.S.) 2 NIH/NIAID/DCR/Integrated Research Facility at Fort Detrick (IRF-Frederick), Frederick, MD 21702, USA; courtney.fi[email protected] (C.L.F.); [email protected] (E.N.P.); [email protected] (Y.C.); [email protected] (S.Y.); [email protected] (J.L.); [email protected] (J.D.) * Correspondence: [email protected] (H.C.S.); [email protected] (J.H.K.); Tel.: +1-585-697-4351 (H.C.S.); +1-301-631-7245 (J.H.K.) † These authors contributed equally to this work. Abstract: Filoviruses, such as Ebola virus and Marburg virus, are of significant human health concern. From 2013 to 2016, Ebola virus caused 11,323 fatalities in Western Africa. Since 2018, two Ebola virus disease outbreaks in the Democratic Republic of the Congo resulted in 2354 fatalities. Although there is progress in medical countermeasure (MCM) development (in particular, vaccines and antibody- based therapeutics), the need for efficacious small-molecule therapeutics remains unmet. Here we describe a novel high-throughput screening assay to identify inhibitors of Ebola virus VP40 matrix protein association with viral particle assembly sites on the interior of the host cell plasma membrane.