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Mukim A, Smith DM, Deshmukh S, Qazi AA, Beliakova-Bethell N. A Camptothetin Analog, Topotecan, Promotes HIV Latency via Interference with HIV Transcription and RNA Splicing. J Virol 2023; 97:e0163022. [PMID: 36719238 PMCID: PMC9973035 DOI: 10.1128/jvi.01630-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 01/11/2023] [Indexed: 02/01/2023] Open
Abstract
Low level HIV transcription during modern antiretroviral therapy (ART) in persons with HIV is linked to residual inflammation and associated diseases, like cardiovascular disease and cancer. The "block and lock" approach to hold HIV in a state of deep latency may help decrease residual inflammation in a person with HIV on ART and thus improve health. A camptothecin analog topotecan (TPT) was previously implicated as an inhibitor of active HIV replication. Using an in vitro primary T cell model of HIV latency, we demonstrated that (i) TPT reduces HIV transcriptional activity in latently infected cells; (ii) downregulation of HIV RNA by TPT cannot be reversed by latency reversing agents; (iii) several primary and secondary mechanism of action of TPT may be involved in control of HIV replication; (iv) regulation of HIV RNA by TPT is dependent on splicing complexity; (v) increase in proportion of unspliced HIV transcripts was facilitated by intron retention and upregulation of splicing factors, specifically SRSF6, by TPT. Although high TPT dosing (10 μM) was needed to achieve the observed effects, viability of primary CD4+ T cells was not greatly affected. Because toxicity can be observed with TPT in persons with cancer, TPT is unlikely to be used as an anti-HIV agent in clinic, but our study provides proof that camptothetin has "block and lock" activity. Other camptothetin analogs, which are less toxic than TPT, should be designed and tested as HIV "block and lock" agents. IMPORTANCE HIV survives in a state of very low activity, called latency, for long periods in persons with HIV on antiretroviral therapy. This low activity of HIV is linked to residual inflammation and associated diseases, such as heart disease and cancer. New strategies are being explored to further silence the HIV provirus and suppress residual inflammation. This study provides strong evidence that the camptothetin analog, Topotecan, can reduce residual activity of HIV in an experimental model of HIV latency. While Topotecan itself is likely not suitable for use in the clinic due to its toxicity, other camptothetin analogs should be designed and investigated as "block and lock" agents.
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Affiliation(s)
- Amey Mukim
- Veterans Medical Research Foundation, San Diego, California, USA
| | - Davey M. Smith
- Department of Medicine, University of California, San Diego, California, USA
| | - Savitha Deshmukh
- Veterans Medical Research Foundation, San Diego, California, USA
| | - Andrew A. Qazi
- Veterans Medical Research Foundation, San Diego, California, USA
| | - Nadejda Beliakova-Bethell
- Veterans Medical Research Foundation, San Diego, California, USA
- Department of Medicine, University of California, San Diego, California, USA
- VA San Diego Healthcare System, San Diego, California, USA
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Dahal S, Clayton K, Been T, Fernet-Brochu R, Ocando AV, Balachandran A, Poirier M, Maldonado RK, Shkreta L, Boligan KF, Guvenc F, Rahman F, Branch D, Bell B, Chabot B, Gray-Owen SD, Parent LJ, Cochrane A. Opposing roles of CLK SR kinases in controlling HIV-1 gene expression and latency. Retrovirology 2022; 19:18. [PMID: 35986377 PMCID: PMC9389714 DOI: 10.1186/s12977-022-00605-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 07/29/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The generation of over 69 spliced HIV-1 mRNAs from one primary transcript by alternative RNA splicing emphasizes the central role that RNA processing plays in HIV-1 replication. Control is mediated in part through the action of host SR proteins whose activity is regulated by multiple SR kinases (CLK1-4, SRPKs). METHODS Both shRNA depletion and small molecule inhibitors of host SR kinases were used in T cell lines and primary cells to evaluate the role of these factors in the regulation of HIV-1 gene expression. Effects on virus expression were assessed using western blotting, RT-qPCR, and immunofluorescence. RESULTS The studies demonstrate that SR kinases play distinct roles; depletion of CLK1 enhanced HIV-1 gene expression, reduction of CLK2 or SRPK1 suppressed it, whereas CLK3 depletion had a modest impact. The opposing effects of CLK1 vs. CLK2 depletion were due to action at distinct steps; reduction of CLK1 increased HIV-1 promoter activity while depletion of CLK2 affected steps after transcript initiation. Reduced CLK1 expression also enhanced the response to several latency reversing agents, in part, by increasing the frequency of responding cells, consistent with a role in regulating provirus latency. To determine whether small molecule modulation of SR kinase function could be used to control HIV-1 replication, we screened a GSK library of protein kinase inhibitors (PKIS) and identified several pyrazolo[1,5-b] pyridazine derivatives that suppress HIV-1 gene expression/replication with an EC50 ~ 50 nM. The compounds suppressed HIV-1 protein and viral RNA accumulation with minimal impact on cell viability, inhibiting CLK1 and CLK2 but not CLK3 function, thereby selectively altering the abundance of individual CLK and SR proteins in cells. CONCLUSIONS These findings demonstrate the unique roles played by individual SR kinases in regulating HIV-1 gene expression, validating the targeting of these functions to either enhance latency reversal, essential for "Kick-and-Kill" strategies, or to silence HIV protein expression for "Block-and-Lock" strategies.
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Affiliation(s)
- Subha Dahal
- grid.17063.330000 0001 2157 2938Dept. of Molecular Genetics, University of Toronto, 1 King’s College Circle, Toronto, ON M5S1A8 Canada
| | - Kiera Clayton
- grid.168645.80000 0001 0742 0364Department of Pathology, University of Massachusetts Medical School, Worcester, MA 01605 USA
| | - Terek Been
- grid.17063.330000 0001 2157 2938Dept. of Molecular Genetics, University of Toronto, 1 King’s College Circle, Toronto, ON M5S1A8 Canada
| | - Raphaële Fernet-Brochu
- grid.17063.330000 0001 2157 2938Dept. of Molecular Genetics, University of Toronto, 1 King’s College Circle, Toronto, ON M5S1A8 Canada
| | - Alonso Villasmil Ocando
- grid.461656.60000 0004 0489 3491Ragon Institute of MGH, MIT and Harvard, Cambridge, MA 02139 USA
| | - Ahalya Balachandran
- grid.17063.330000 0001 2157 2938Dept. of Molecular Genetics, University of Toronto, 1 King’s College Circle, Toronto, ON M5S1A8 Canada
| | - Mikaël Poirier
- grid.86715.3d0000 0000 9064 6198Dept. of Microbiology & Infectious Diseases, Université de Sherbrooke, Sherbrooke, QC Canada
| | - Rebecca Kaddis Maldonado
- grid.240473.60000 0004 0543 9901Department of Medicine, Penn State College of Medicine, Hershey, PA 17033 USA ,grid.240473.60000 0004 0543 9901Microbiology & Immunology, Penn State College of Medicine, Hershey, PA 17033 USA
| | - Lulzim Shkreta
- grid.86715.3d0000 0000 9064 6198Dept. of Microbiology & Infectious Diseases, Université de Sherbrooke, Sherbrooke, QC Canada
| | - Kayluz Frias Boligan
- grid.423370.10000 0001 0285 1288Center for Innovation, Canadian Blood Services, Toronto, ON Canada
| | - Furkan Guvenc
- grid.17063.330000 0001 2157 2938Dept. of Molecular Genetics, University of Toronto, 1 King’s College Circle, Toronto, ON M5S1A8 Canada
| | - Fariha Rahman
- grid.17063.330000 0001 2157 2938Dept. of Molecular Genetics, University of Toronto, 1 King’s College Circle, Toronto, ON M5S1A8 Canada
| | - Donald Branch
- grid.423370.10000 0001 0285 1288Center for Innovation, Canadian Blood Services, Toronto, ON Canada
| | - Brendan Bell
- grid.86715.3d0000 0000 9064 6198Dept. of Microbiology & Infectious Diseases, Université de Sherbrooke, Sherbrooke, QC Canada
| | - Benoit Chabot
- grid.86715.3d0000 0000 9064 6198Dept. of Microbiology & Infectious Diseases, Université de Sherbrooke, Sherbrooke, QC Canada
| | - Scott D. Gray-Owen
- grid.17063.330000 0001 2157 2938Dept. of Molecular Genetics, University of Toronto, 1 King’s College Circle, Toronto, ON M5S1A8 Canada
| | - Leslie J. Parent
- grid.240473.60000 0004 0543 9901Department of Medicine, Penn State College of Medicine, Hershey, PA 17033 USA ,grid.240473.60000 0004 0543 9901Microbiology & Immunology, Penn State College of Medicine, Hershey, PA 17033 USA
| | - Alan Cochrane
- grid.17063.330000 0001 2157 2938Dept. of Molecular Genetics, University of Toronto, 1 King’s College Circle, Toronto, ON M5S1A8 Canada
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Trypsteen W, White CH, Mukim A, Spina CA, De Spiegelaere W, Lefever S, Planelles V, Bosque A, Woelk CH, Vandekerckhove L, Beliakova-Bethell N. Long non-coding RNAs and latent HIV - A search for novel targets for latency reversal. PLoS One 2019; 14:e0224879. [PMID: 31710657 PMCID: PMC6844474 DOI: 10.1371/journal.pone.0224879] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 10/23/2019] [Indexed: 12/23/2022] Open
Abstract
The latent cellular reservoir of HIV is recognized as the major barrier to cure from HIV infection. Long non-coding RNAs (lncRNAs) are more tissue and cell type-specific than protein coding genes, and may represent targets of choice for HIV latency reversal. Using two in vitro primary T-cell models, we identified lncRNAs dysregulated in latency. PVT1 and RP11-347C18.3 were up-regulated in common between the two models, and RP11-539L10.2 was down-regulated. The major component of the latent HIV reservoir, memory CD4+ T-cells, had higher expression of these lncRNAs, compared to naïve T-cells. Guilt-by-association analysis demonstrated that lncRNAs dysregulated in latency were associated with several cellular pathways implicated in HIV latency establishment and maintenance: proteasome, spliceosome, p53 signaling, and mammalian target of rapamycin (MTOR). PVT1, RP11-347C18.3, and RP11-539L10.2 were down-regulated by latency reversing agents, suberoylanilide hydroxamic acid and Romidepsin, suggesting that modulation of lncRNAs is a possible secondary mechanism of action of these compounds. These results will facilitate prioritization of lncRNAs for evaluation as targets for HIV latency reversal. Importantly, our study provides insights into regulatory function of lncRNA during latent HIV infection.
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Affiliation(s)
- Wim Trypsteen
- HIV Cure Research Center, Department of Internal Medicine, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Cory H. White
- Faculty of Medicine, University of Southampton, Southampton, Hants, United Kingdom
| | - Amey Mukim
- San Diego VA Medical Center and Veterans Medical Research Foundation, San Diego, CA, United States of America
| | - Celsa A. Spina
- San Diego VA Medical Center and Veterans Medical Research Foundation, San Diego, CA, United States of America
- Department of Pathology, University of California San Diego, La Jolla, CA, United States of America
| | - Ward De Spiegelaere
- Department of Morphology, Faculty of Veterinary Sciences, Ghent University, Ghent, Belgium
| | - Steve Lefever
- Center for Medical Genetics, Ghent University, Ghent, Belgium
| | - Vicente Planelles
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, United States of America
| | - Alberto Bosque
- Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Washington, DC, United States of America
| | - Christopher H. Woelk
- Faculty of Medicine, University of Southampton, Southampton, Hants, United Kingdom
| | - Linos Vandekerckhove
- HIV Cure Research Center, Department of Internal Medicine, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Nadejda Beliakova-Bethell
- San Diego VA Medical Center and Veterans Medical Research Foundation, San Diego, CA, United States of America
- Department of Medicine, University of California San Diego, La Jolla, CA, United States of America
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4
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Control of HIV-1 gene expression by SR proteins. Biochem Soc Trans 2017; 44:1417-1425. [PMID: 27911724 DOI: 10.1042/bst20160113] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 07/08/2016] [Accepted: 07/12/2016] [Indexed: 12/24/2022]
Abstract
Cellular proteins are required for all steps of human immunodeficiency virus type 1 (HIV-1) gene expression including transcription, splicing, 3'-end formation/polyadenylation, nuclear export and translation. SR proteins are a family of cellular RNA-binding proteins that regulate and functionally integrate multiple steps of gene expression. Specific SR proteins are best characterised for regulating HIV-1 RNA splicing by binding specific locations in the viral RNA, though recently they have also been shown to control transcription, 3'-end formation, and translation. Due to their importance in regulating HIV-1 gene expression, SR proteins and their regulatory factors are potential antiviral drug targets.
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Dlamini Z, Hull R. Can the HIV-1 splicing machinery be targeted for drug discovery? HIV AIDS-RESEARCH AND PALLIATIVE CARE 2017; 9:63-75. [PMID: 28331370 PMCID: PMC5354533 DOI: 10.2147/hiv.s120576] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
HIV-1 is able to express multiple protein types and isoforms from a single 9 kb mRNA transcript. These proteins are also expressed at particular stages of viral development, and this is achieved through the control of alternative splicing and the export of these transcripts from the nucleus. The nuclear export is controlled by the HIV protein Rev being required to transport incompletely spliced and partially spliced mRNA from the nucleus where they are normally retained. This implies a close relationship between the control of alternate splicing and the nuclear export of mRNA in the control of HIV-1 viral proliferation. This review discusses both the processes. The specificity and regulation of splicing in HIV-1 is controlled by the use of specific splice sites as well as exonic splicing enhancer and exonic splicing silencer sequences. The use of these silencer and enhancer sequences is dependent on the serine arginine family of proteins as well as the heterogeneous nuclear ribonucleoprotein family of proteins that bind to these sequences and increase or decrease splicing. Since alternative splicing is such a critical factor in viral development, it presents itself as a promising drug target. This review aims to discuss the inhibition of splicing, which would stall viral development, as an anti-HIV therapeutic strategy. In this review, the most recent knowledge of splicing in human immunodeficiency viral development and the latest therapeutic strategies targeting human immunodeficiency viral splicing are discussed.
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Affiliation(s)
- Zodwa Dlamini
- Research, Innovation & Engagements Portfolio, Mangosuthu University of Technology, Durban, South Africa
| | - Rodney Hull
- Research, Innovation & Engagements Portfolio, Mangosuthu University of Technology, Durban, South Africa
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6
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Finley J. Reactivation of latently infected HIV-1 viral reservoirs and correction of aberrant alternative splicing in the LMNA gene via AMPK activation: Common mechanism of action linking HIV-1 latency and Hutchinson–Gilford progeria syndrome. Med Hypotheses 2015; 85:320-32. [DOI: 10.1016/j.mehy.2015.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 05/25/2015] [Accepted: 06/08/2015] [Indexed: 12/30/2022]
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Balanced splicing at the Tat-specific HIV-1 3'ss A3 is critical for HIV-1 replication. Retrovirology 2015; 12:29. [PMID: 25889056 PMCID: PMC4422144 DOI: 10.1186/s12977-015-0154-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 02/26/2015] [Indexed: 11/12/2022] Open
Abstract
Background The viral regulatory protein Tat is essential for establishing a productive transcription from the 5′-LTR promoter during the early phase of viral gene expression. Formation of the Tat-encoding mRNAs requires splicing at the viral 3′ss A3, which has previously been shown to be both negatively and positively regulated by the downstream splicing regulatory elements (SREs) ESS2p and ESE2/ESS2. However, using the novel RESCUE-type computational HEXplorer algorithm, we were recently able to identify another splicing enhancer (ESE5807-5838, henceforth referred to as ESEtat) located between ESS2p and ESE2/ESS2. Here we show that ESEtat has a great impact on viral tat-mRNA splicing and that it is fundamental for regulated 3′ss A3 usage. Results Mutational inactivation or locked nucleic acid (LNA)-directed masking of the ESEtat sequence in the context of a replication-competent virus was associated with a failure (i) to activate viral 3′ss A3 and (ii) to accumulate Tat-encoding mRNA species. Consequently, due to insufficient amounts of Tat protein efficient viral replication was drastically impaired. RNA in vitro binding assays revealed SRSF2 and SRSF6 as candidate splicing factors acting through ESEtat and ESE2 for 3′ss A3 activation. This notion was supported by coexpression experiments, in which wild-type, but not ESEtat-negative provirus responded to higher levels of SRSF2 and SRSF6 proteins with higher levels of tat-mRNA splicing. Remarkably, we could also find that SRSF6 overexpression established an antiviral state within provirus-transfected cells, efficiently blocking virus particle production. For the anti-HIV-1 activity the arginine-serine (RS)-rich domain of the splicing factor was dispensable. Conclusions Based on our results, we propose that splicing at 3′ss A3 is dependent on binding of the enhancing SR proteins SRSF2 and SRSF6 to the ESEtat and ESE2 sequence. Mutational inactivation or interference specifically with ESEtat activity by LNA-directed masking seem to account for an early stage defect in viral gene expression, probably by cutting off the supply line of Tat that HIV needs to efficiently transcribe its genome.
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8
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Rubicz R, Yolken R, Drigalenko E, Carless MA, Dyer TD, Kent J, Curran JE, Johnson MP, Cole SA, Fowler SP, Arya R, Puppala S, Almasy L, Moses EK, Kraig E, Duggirala R, Blangero J, Leach CT, Göring HHH. Genome-wide genetic investigation of serological measures of common infections. Eur J Hum Genet 2015; 23:1544-8. [PMID: 25758998 DOI: 10.1038/ejhg.2015.24] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 12/09/2014] [Accepted: 01/27/2015] [Indexed: 12/16/2022] Open
Abstract
Populations and individuals differ in susceptibility to infections because of a number of factors, including host genetic variation. We previously demonstrated that differences in antibody titer, which reflect infection history, are significantly heritable. Here we attempt to identify the genetic factors influencing variation in these serological phenotypes. Blood samples from >1300 Mexican Americans were quantified for IgG antibody level against 12 common infections, selected on the basis of their reported role in cardiovascular disease risk: Chlamydia pneumoniae; Helicobacter pylori; Toxoplasma gondii; cytomegalovirus; herpes simplex I virus; herpes simplex II virus; human herpesvirus 6 (HHV6); human herpesvirus 8 (HHV8); varicella zoster virus; hepatitis A virus (HAV); influenza A virus; and influenza B virus. Pathogen-specific quantitative antibody levels were analyzed, as were three measures of pathogen burden. Genome-wide linkage and joint linkage and association analyses were performed using ~1 million SNPs. Significant linkage (lod scores >3.0) was obtained for HHV6 (on chromosome 7), HHV8 (on chromosome 6), and HAV (on chromosome 13). SNP rs4812712 on chromosome 20 was significantly associated with C. pneumoniae (P=5.3 × 10(-8)). However, no genome-wide significant loci were obtained for the other investigated antibodies. We conclude that it is possible to localize host genetic factors influencing some of these antibody traits, but that further larger-scale investigations will be required to elucidate the genetic mechanisms contributing to variation in antibody levels.
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Affiliation(s)
- Rohina Rubicz
- Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Robert Yolken
- Stanley Division of Developmental Neurovirology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Eugene Drigalenko
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Melanie A Carless
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Thomas D Dyer
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Jack Kent
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Joanne E Curran
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Matthew P Johnson
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Shelley A Cole
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Sharon P Fowler
- Division of Clinical Epidemiology, Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Rector Arya
- Division of Endocrinology and Diabetes, Department of Pediatrics, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Sobha Puppala
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Laura Almasy
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Eric K Moses
- Center for Genetic Epidemiology and Biostatistics, The University of Western Australia, Perth, WA, Australia
| | - Ellen Kraig
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | | | - John Blangero
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Charles T Leach
- Department of Pediatrics, Section of Infectious Diseases, Baylor College of Medicine/Children's Hospital of San Antonio, San Antonio, TX, USA
| | - Harald H H Göring
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA
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Aberrant splicing of HTT generates the pathogenic exon 1 protein in Huntington disease. Proc Natl Acad Sci U S A 2013; 110:2366-70. [PMID: 23341618 DOI: 10.1073/pnas.1221891110] [Citation(s) in RCA: 351] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Huntington disease (HD) is a devastating, late-onset, inherited neurodegenerative disorder that manifests with personality changes, movement disorders, and cognitive decline. It is caused by a CAG repeat expansion in exon 1 of the HTT gene that translates to a polyglutamine tract in the huntingtin protein (HTT). The formation of HTT fragments has been implicated as an essential step in the molecular pathogenesis of HD and several proteases that cleave HTT have been identified. However, the importance of smaller N-terminal fragments has been highlighted by their presence in HD postmortem brains and by the fact that nuclear inclusions are only detected by antibodies to the N terminus of HTT. Despite an intense research effort, the precise length of these fragments and the mechanism by which they are generated remains unknown. Here we show that CAG repeat length-dependent aberrant splicing of exon 1 HTT results in a short polyadenylated mRNA that is translated into an exon 1 HTT protein. Given that mutant exon 1 HTT proteins have consistently been shown to be highly pathogenic in HD mouse models, the aberrant splicing of HTT mRNA provides a mechanistic basis for the molecular pathogenesis of HD. RNA-targeted therapeutic strategies designed to lower the levels of HTT are under development. Many of these approaches would not prevent the production of exon 1 HTT and should be reviewed in light of our findings.
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Yin X, Jin N, Gu J, Shi J, Zhou J, Gong CX, Iqbal K, Grundke-Iqbal I, Liu F. Dual-specificity tyrosine phosphorylation-regulated kinase 1A (Dyrk1A) modulates serine/arginine-rich protein 55 (SRp55)-promoted Tau exon 10 inclusion. J Biol Chem 2012; 287:30497-506. [PMID: 22767602 PMCID: PMC3436298 DOI: 10.1074/jbc.m112.355412] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 06/10/2012] [Indexed: 11/06/2022] Open
Abstract
Tau exon 10, which encodes the second microtubule-binding repeat, is regulated by alternative splicing. Its alternative splicing generates Tau isoforms with three- or four-microtubule-binding repeats, named 3R-tau and 4R-tau. Adult human brain expresses equal levels of 3R-tau and 4R-tau. Imbalance of 3R-tau and 4R-tau causes Tau aggregation and neurofibrillary degeneration. In the present study, we found that splicing factor SRp55 (serine/arginine-rich protein 55) promoted Tau exon 10 inclusion. Knockdown of SRp55 significantly promoted Tau exon 10 exclusion. The promotion of Tau exon 10 inclusion by SRp55 required the arginine/serine-rich region, which was responsible for the subnucleic speckle localization. Dyrk1A (dual specificity tyrosine-phosphorylated and regulated kinase 1A) interacted with SRp55 and mainly phosphorylated its proline-rich domain. Phosphorylation of SRp55 by Dyrk1A suppressed its ability to promote Tau exon 10 inclusion. Up-regulation of Dyrk1A as in Down syndrome could lead to neurofibrillary degeneration by shifting the alternative splicing of Tau exon 10 to an increase in the ratio of 3R-tau/4R-tau.
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Affiliation(s)
- Xiaomin Yin
- From the Jiangsu Key Laboratory of Neuroregeneration and
- the Department of Biochemistry and Molecular Biology, Medical School, Nantong University, Nantong, Jiangsu, 226001, China and
| | - Nana Jin
- From the Jiangsu Key Laboratory of Neuroregeneration and
| | - Jianlan Gu
- From the Jiangsu Key Laboratory of Neuroregeneration and
- the Department of Biochemistry and Molecular Biology, Medical School, Nantong University, Nantong, Jiangsu, 226001, China and
| | - Jianhua Shi
- From the Jiangsu Key Laboratory of Neuroregeneration and
- the Department of Biochemistry and Molecular Biology, Medical School, Nantong University, Nantong, Jiangsu, 226001, China and
| | - Jianhua Zhou
- From the Jiangsu Key Laboratory of Neuroregeneration and
| | - Cheng-Xin Gong
- From the Jiangsu Key Laboratory of Neuroregeneration and
- the Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314
| | - Khalid Iqbal
- the Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314
| | - Inge Grundke-Iqbal
- the Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314
| | - Fei Liu
- From the Jiangsu Key Laboratory of Neuroregeneration and
- the Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314
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Ocwieja KE, Sherrill-Mix S, Mukherjee R, Custers-Allen R, David P, Brown M, Wang S, Link DR, Olson J, Travers K, Schadt E, Bushman FD. Dynamic regulation of HIV-1 mRNA populations analyzed by single-molecule enrichment and long-read sequencing. Nucleic Acids Res 2012; 40:10345-55. [PMID: 22923523 PMCID: PMC3488221 DOI: 10.1093/nar/gks753] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Alternative RNA splicing greatly expands the repertoire of proteins encoded by genomes. Next-generation sequencing (NGS) is attractive for studying alternative splicing because of the efficiency and low cost per base, but short reads typical of NGS only report mRNA fragments containing one or few splice junctions. Here, we used single-molecule amplification and long-read sequencing to study the HIV-1 provirus, which is only 9700 bp in length, but encodes nine major proteins via alternative splicing. Our data showed that the clinical isolate HIV-1(89.6) produces at least 109 different spliced RNAs, including a previously unappreciated ∼1 kb class of messages, two of which encode new proteins. HIV-1 message populations differed between cell types, longitudinally during infection, and among T cells from different human donors. These findings open a new window on a little studied aspect of HIV-1 replication, suggest therapeutic opportunities and provide advanced tools for the study of alternative splicing.
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Affiliation(s)
- Karen E Ocwieja
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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