1
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Jin J, Bai H, Yan H, Deng T, Li T, Xiao R, Fan L, Bai X, Ning H, Liu Z, Zhang K, Wu X, Liang K, Ma P, Gao X, Hu D. PRMT2 promotes HIV-1 latency by preventing nucleolar exit and phase separation of Tat into the Super Elongation Complex. Nat Commun 2023; 14:7274. [PMID: 37949879 PMCID: PMC10638354 DOI: 10.1038/s41467-023-43060-1] [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: 05/20/2023] [Accepted: 10/30/2023] [Indexed: 11/12/2023] Open
Abstract
The HIV-1 Tat protein hijacks the Super Elongation Complex (SEC) to stimulate viral transcription and replication. However, the mechanisms underlying Tat activation and inactivation, which mediate HIV-1 productive and latent infection, respectively, remain incompletely understood. Here, through a targeted complementary DNA (cDNA) expression screening, we identify PRMT2 as a key suppressor of Tat activation, thus contributing to proviral latency in multiple cell line latency models and in HIV-1-infected patient CD4+ T cells. Our data reveal that the transcriptional activity of Tat is oppositely regulated by NPM1-mediated nucleolar retention and AFF4-induced phase separation in the nucleoplasm. PRMT2 preferentially methylates Tat arginine 52 (R52) to reinforce its nucleolar sequestration while simultaneously counteracting its incorporation into the SEC droplets, thereby leading to its functional inactivation to promote proviral latency. Thus, our studies unveil a central and unappreciated role for Tat methylation by PRMT2 in connecting its subnuclear distribution, liquid droplet formation, and transactivating function, which could be therapeutically targeted to eradicate latent viral reservoirs.
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Affiliation(s)
- Jiaxing Jin
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China
| | - Hui Bai
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China
| | - Han Yan
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China
| | - Ting Deng
- Key Laboratory of Breast Cancer Prevention and Therapy of Ministry of Education, Key Laboratory of Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital, 300060, Tianjin, China
| | - Tianyu Li
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, 430071, Wuhan, China
| | - Ruijing Xiao
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, 430071, Wuhan, China
| | - Lina Fan
- Department of Infectious Diseases, Tianjin Second People's Hospital, Nankai University, 300192, Tianjin, China
| | - Xue Bai
- The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, School of Basic Medical Sciences, Tianjin Medical University, 300070, Tianjin, China
| | - Hanhan Ning
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China
| | - Zhe Liu
- The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, School of Basic Medical Sciences, Tianjin Medical University, 300070, Tianjin, China
| | - Kai Zhang
- The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, School of Basic Medical Sciences, Tianjin Medical University, 300070, Tianjin, China
| | - Xudong Wu
- The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, School of Basic Medical Sciences, Tianjin Medical University, 300070, Tianjin, China
| | - Kaiwei Liang
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, 430071, Wuhan, China
| | - Ping Ma
- Department of Infectious Diseases, Tianjin Second People's Hospital, Nankai University, 300192, Tianjin, China.
| | - Xin Gao
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, 300020, Tianjin, China.
- Tianjin Institutes of Health Science, 301600, Tianjin, China.
| | - Deqing Hu
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China.
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2
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Pluta AJ, Studniarek C, Murphy S, Norbury CJ. Cyclin-dependent kinases: Masters of the eukaryotic universe. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 15:e1816. [PMID: 37718413 PMCID: PMC10909489 DOI: 10.1002/wrna.1816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 07/21/2023] [Accepted: 08/03/2023] [Indexed: 09/19/2023]
Abstract
A family of structurally related cyclin-dependent protein kinases (CDKs) drives many aspects of eukaryotic cell function. Much of the literature in this area has considered individual members of this family to act primarily either as regulators of the cell cycle, the context in which CDKs were first discovered, or as regulators of transcription. Until recently, CDK7 was the only clear example of a CDK that functions in both processes. However, new data points to several "cell-cycle" CDKs having important roles in transcription and some "transcriptional" CDKs having cell cycle-related targets. For example, novel functions in transcription have been demonstrated for the archetypal cell cycle regulator CDK1. The increasing evidence of the overlap between these two CDK types suggests that they might play a critical role in coordinating the two processes. Here we review the canonical functions of cell-cycle and transcriptional CDKs, and provide an update on how these kinases collaborate to perform important cellular functions. We also provide a brief overview of how dysregulation of CDKs contributes to carcinogenesis, and possible treatment avenues. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Processing > 3' End Processing RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
| | | | - Shona Murphy
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
| | - Chris J. Norbury
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
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3
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Hafer TL, Felton A, Delgado Y, Srinivasan H, Emerman M. A CRISPR Screen of HIV Dependency Factors Reveals That CCNT1 Is Non-Essential in T Cells but Required for HIV-1 Reactivation from Latency. Viruses 2023; 15:1863. [PMID: 37766271 PMCID: PMC10535513 DOI: 10.3390/v15091863] [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: 07/28/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023] Open
Abstract
We sought to explore the hypothesis that host factors required for HIV-1 replication also play a role in latency reversal. Using a CRISPR gene library of putative HIV dependency factors, we performed a screen to identify genes required for latency reactivation. We identified several HIV-1 dependency factors that play a key role in HIV-1 latency reactivation including ELL, UBE2M, TBL1XR1, HDAC3, AMBRA1, and ALYREF. The knockout of Cyclin T1 (CCNT1), a component of the P-TEFb complex that is important for transcription elongation, was the top hit in the screen and had the largest effect on HIV latency reversal with a wide variety of latency reversal agents. Moreover, CCNT1 knockout prevents latency reactivation in a primary CD4+ T cell model of HIV latency without affecting the activation of these cells. RNA sequencing data showed that CCNT1 regulates HIV-1 proviral genes to a larger extent than any other host gene and had no significant effects on RNA transcripts in primary T cells after activation. We conclude that CCNT1 function is non-essential in T cells but is absolutely required for HIV latency reversal.
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Affiliation(s)
- Terry L. Hafer
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA 98195, USA;
| | - Abby Felton
- Divisions of Human Biology and Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Yennifer Delgado
- Divisions of Human Biology and Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Harini Srinivasan
- Bioinformatics Shared Resource, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Michael Emerman
- Divisions of Human Biology and Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
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4
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Hafer TL, Felton A, Delgado Y, Srinivasan H, Emerman M. A CRISPR screen of HIV dependency factors reveals CCNT1 is non-essential in T cells but required for HIV-1 reactivation from latency. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.28.551016. [PMID: 37546973 PMCID: PMC10402164 DOI: 10.1101/2023.07.28.551016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
We sought to explore the hypothesis that host factors required for HIV-1 replication also play a role in latency reversal. Using a CRISPR gene library of putative HIV dependency factors, we performed a screen to identify genes required for latency reactivation. We identified several HIV-1 dependency factors that play a key role in HIV-1 latency reactivation including ELL , UBE2M , TBL1XR1 , HDAC3 , AMBRA1 , and ALYREF . Knockout of Cyclin T1 ( CCNT1 ), a component of the P-TEFb complex important for transcription elongation, was the top hit in the screen and had the largest effect on HIV latency reversal with a wide variety of latency reversal agents. Moreover, CCNT1 knockout prevents latency reactivation in a primary CD4+ T cell model of HIV latency without affecting activation of these cells. RNA sequencing data showed that CCNT1 regulates HIV-1 proviral genes to a larger extent than any other host gene and had no significant effects on RNA transcripts in primary T cells after activation. We conclude that CCNT1 function is redundant in T cells but is absolutely required for HIV latency reversal.
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Affiliation(s)
- Terry L Hafer
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA 98195, USA
| | - Abby Felton
- Divisions of Human Biology and Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Yennifer Delgado
- Divisions of Human Biology and Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Harini Srinivasan
- Bioinformatics Shared Resource, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Michael Emerman
- Divisions of Human Biology and Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
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5
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Wasserman JS, Feiser F, Palacio S, Patel K, Gonzalez J, Fowle H, Graña X. Protocol to assess substrate dephosphorylation by serine/threonine phosphoprotein phosphatases in vitro. STAR Protoc 2023; 4:102148. [PMID: 37074907 DOI: 10.1016/j.xpro.2023.102148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/18/2023] [Accepted: 02/10/2023] [Indexed: 04/20/2023] Open
Abstract
Serine/threonine protein phosphatase 2 (PP2A) forms heterotrimeric holoenzymes, where a scaffold subunit bridges the PP2A catalytic subunit to a B regulatory subunit, e.g., B55α. The PP2A/B55α holoenzyme plays key roles in signaling and cell-cycle control targeting multiple substrates. Here, we describe semiquantitative approaches to determine PP2A/B55α substrate specificity. Parts I and II detail approaches to assess PP2A/B55α-mediated dephosphorylation of immobilized substrate peptide variants. Parts III and IV detail methods to assess PP2A/B55α-substrate-binding specificity. These approaches are adaptable to other serine/threonine phosphatases. For complete details on the use and execution of this protocol, please refer to Fowle et al..1.
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Affiliation(s)
- Jason S Wasserman
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA.
| | - Felicity Feiser
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Seren Palacio
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Kishan Patel
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Joy Gonzalez
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Holly Fowle
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA
| | - Xavier Graña
- Fels Cancer Institute for Personalized Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA.
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6
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Huang F, Feng Y, Peterlin BM, Fujinaga K. P-TEFb is degraded by Siah1/2 in quiescent cells. Nucleic Acids Res 2022; 50:5000-5013. [PMID: 35524561 PMCID: PMC9122529 DOI: 10.1093/nar/gkac291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 04/05/2022] [Accepted: 04/12/2022] [Indexed: 11/12/2022] Open
Abstract
P-TEFb, composed of CycT1 and CDK9, regulates the elongation of transcription by RNA polymerase II. In proliferating cells, it is regulated by 7SK snRNA in the 7SK snRNP complex. In resting cells, P-TEFb is absent, because CycT1 is dephosphorylated, released from CDK9 and rapidly degraded. In this study, we identified the mechanism of this degradation. We mapped the ubiquitination and degradation of free CycT1 to its N-terminal region from positions 1 to 280. This region is ubiquitinated at six lysines, where E3 ligases Siah1 and Siah2 bind and degrade these sequences. Importantly, the inhibition of Siah1/2 rescued the expression of free CycT1 in proliferating as well as resting primary cells. We conclude that Siah1/2 are the E3 ligases that bind and degrade the dissociated CycT1 in resting, terminally differentiated, anergic and/or exhausted cells.
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Affiliation(s)
- Fang Huang
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Yongmei Feng
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - B Matija Peterlin
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Koh Fujinaga
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
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7
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Huang F, Nguyen TT, Echeverria I, Rakesh R, Cary DC, Paculova H, Sali A, Weiss A, Peterlin BM, Fujinaga K. Reversible phosphorylation of cyclin T1 promotes assembly and stability of P-TEFb. eLife 2021; 10:68473. [PMID: 34821217 PMCID: PMC8648303 DOI: 10.7554/elife.68473] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 11/19/2021] [Indexed: 01/06/2023] Open
Abstract
The positive transcription elongation factor b (P-TEFb) is a critical coactivator for transcription of most cellular and viral genes, including those of HIV. While P-TEFb is regulated by 7SK snRNA in proliferating cells, P-TEFb is absent due to diminished levels of CycT1 in quiescent and terminally differentiated cells, which has remained unexplored. In these cells, we found that CycT1 not bound to CDK9 is rapidly degraded. Moreover, productive CycT1:CDK9 interactions are increased by PKC-mediated phosphorylation of CycT1 in human cells. Conversely, dephosphorylation of CycT1 by PP1 reverses this process. Thus, PKC inhibitors or removal of PKC by chronic activation results in P-TEFb disassembly and CycT1 degradation. This finding not only recapitulates P-TEFb depletion in resting CD4+ T cells but also in anergic T cells. Importantly, our studies reveal mechanisms of P-TEFb inactivation underlying T cell quiescence, anergy, and exhaustion as well as proviral latency and terminally differentiated cells.
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Affiliation(s)
- Fang Huang
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States
| | - Trang Tt Nguyen
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States.,The Howard Hughes Medical Institute, San Francisco, United States
| | - Ignacia Echeverria
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, United States.,Departmentof Cellular Molecular Pharmacology, California Institute for Quantitative Biosciences (QBI), and Department of Bioengineering and Therapeutic Sciences, San Francisco, United States
| | - Ramachandran Rakesh
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, United States.,Departmentof Cellular Molecular Pharmacology, California Institute for Quantitative Biosciences (QBI), and Department of Bioengineering and Therapeutic Sciences, San Francisco, United States
| | - Daniele C Cary
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States
| | - Hana Paculova
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, United States.,Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences (QBI), San Francisco, United States
| | - Arthur Weiss
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States.,The Howard Hughes Medical Institute, San Francisco, United States
| | - Boris Matija Peterlin
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States
| | - Koh Fujinaga
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States
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8
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Tantale K, Garcia-Oliver E, Robert MC, L'Hostis A, Yang Y, Tsanov N, Topno R, Gostan T, Kozulic-Pirher A, Basu-Shrivastava M, Mukherjee K, Slaninova V, Andrau JC, Mueller F, Basyuk E, Radulescu O, Bertrand E. Stochastic pausing at latent HIV-1 promoters generates transcriptional bursting. Nat Commun 2021; 12:4503. [PMID: 34301927 PMCID: PMC8302722 DOI: 10.1038/s41467-021-24462-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 06/17/2021] [Indexed: 02/06/2023] Open
Abstract
Promoter-proximal pausing of RNA polymerase II is a key process regulating gene expression. In latent HIV-1 cells, it prevents viral transcription and is essential for latency maintenance, while in acutely infected cells the viral factor Tat releases paused polymerase to induce viral expression. Pausing is fundamental for HIV-1, but how it contributes to bursting and stochastic viral reactivation is unclear. Here, we performed single molecule imaging of HIV-1 transcription. We developed a quantitative analysis method that manages multiple time scales from seconds to days and that rapidly fits many models of promoter dynamics. We found that RNA polymerases enter a long-lived pause at latent HIV-1 promoters (>20 minutes), thereby effectively limiting viral transcription. Surprisingly and in contrast to current models, pausing appears stochastic and not obligatory, with only a small fraction of the polymerases undergoing long-lived pausing in absence of Tat. One consequence of stochastic pausing is that HIV-1 transcription occurs in bursts in latent cells, thereby facilitating latency exit and providing a rationale for the stochasticity of viral rebounds.
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Affiliation(s)
- Katjana Tantale
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Encar Garcia-Oliver
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Marie-Cécile Robert
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France
| | - Adèle L'Hostis
- LPHI, UMR CNRS 5235, University of Montpellier, Montpellier, France
| | - Yueyuxiao Yang
- LPHI, UMR CNRS 5235, University of Montpellier, Montpellier, France
| | - Nikolay Tsanov
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Rachel Topno
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France
- LPHI, UMR CNRS 5235, University of Montpellier, Montpellier, France
| | - Thierry Gostan
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Alja Kozulic-Pirher
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Meenakshi Basu-Shrivastava
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Kamalika Mukherjee
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Vera Slaninova
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France
| | - Jean-Christophe Andrau
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Florian Mueller
- Unité Imagerie et Modélisation, Institut Pasteur and CNRS UMR 3691, Paris, France
| | - Eugenia Basyuk
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France.
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France.
- Microbiology Fundamental and Pathogenicity CNRS UMR 5234, University of Bordeaux, Bordeaux, France.
| | - Ovidiu Radulescu
- LPHI, UMR CNRS 5235, University of Montpellier, Montpellier, France.
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France.
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France.
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France.
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9
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Eyvazi S, Hejazi MS, Kahroba H, Abasi M, Zamiri RE, Tarhriz V. CDK9 as an Appealing Target for Therapeutic Interventions. Curr Drug Targets 2020; 20:453-464. [PMID: 30362418 DOI: 10.2174/1389450119666181026152221] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 10/15/2018] [Accepted: 10/16/2018] [Indexed: 02/05/2023]
Abstract
Cyclin Dependent Kinase 9 (CDK9) as a serine/threonine kinase belongs to a great number of CDKs. CDK9 is the main core of PTEF-b complex and phosphorylates RNA polymerase (RNAP) II besides other transcription factors which regulate gene transcription elongation in numerous physiological processes. Multi-functional nature of CDK9 in diverse cellular pathways proposes that it is as an appealing target. In this review, we summarized the recent findings on the molecular interaction of CDK9 with critical participant molecules to modulate their activity in various diseases. Furthermore, the presented review provides a rationale supporting the use of CDK9 as a therapeutic target in clinical developments for crucial diseases; particularly cancers will be reviewed.
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Affiliation(s)
- Shirin Eyvazi
- Molecular Medicine Research Center, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran.,Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Saeid Hejazi
- Molecular Medicine Research Center, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran.,Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Molecular Medicine, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Homan Kahroba
- Molecular Medicine Research Center, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Molecular Medicine, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mozghan Abasi
- Molecular Medicine Research Center, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran.,Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Reza Eghdam Zamiri
- Faculty of medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Vahideh Tarhriz
- Molecular Medicine Research Center, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
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10
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P-TEFb as A Promising Therapeutic Target. Molecules 2020; 25:molecules25040838. [PMID: 32075058 PMCID: PMC7070488 DOI: 10.3390/molecules25040838] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 01/19/2023] Open
Abstract
The positive transcription elongation factor b (P-TEFb) was first identified as a general factor that stimulates transcription elongation by RNA polymerase II (RNAPII), but soon afterwards it turned out to be an essential cellular co-factor of human immunodeficiency virus (HIV) transcription mediated by viral Tat proteins. Studies on the mechanisms of Tat-dependent HIV transcription have led to radical advances in our knowledge regarding the mechanism of eukaryotic transcription, including the discoveries that P-TEFb-mediated elongation control of cellular transcription is a main regulatory step of gene expression in eukaryotes, and deregulation of P-TEFb activity plays critical roles in many human diseases and conditions in addition to HIV/AIDS. P-TEFb is now recognized as an attractive and promising therapeutic target for inflammation/autoimmune diseases, cardiac hypertrophy, cancer, infectious diseases, etc. In this review article, I will summarize our knowledge about basic P-TEFb functions, the regulatory mechanism of P-TEFb-dependent transcription, P-TEFb’s involvement in biological processes and diseases, and current approaches to manipulating P-TEFb functions for the treatment of these diseases.
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11
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Gagne M, Michaels D, Schiralli Lester GM, Gummuluru S, Wong WW, Henderson AJ. Strength of T cell signaling regulates HIV-1 replication and establishment of latency. PLoS Pathog 2019; 15:e1007802. [PMID: 31116788 PMCID: PMC6548398 DOI: 10.1371/journal.ppat.1007802] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/04/2019] [Accepted: 04/30/2019] [Indexed: 01/27/2023] Open
Abstract
A major barrier to curing HIV-1 is the long-lived latent reservoir that supports re-emergence of HIV-1 upon treatment interruption. Targeting this reservoir will require mechanistic insights into the establishment and maintenance of HIV-1 latency. Whether T cell signaling at the time of HIV-1 infection influences productive replication or latency is not fully understood. We used a panel of chimeric antigen receptors (CARs) with different ligand binding affinities to induce a range of signaling strengths to model differential T cell receptor signaling at the time of HIV-1 infection. Stimulation of T cell lines or primary CD4+ T cells expressing chimeric antigen receptors supported HIV-1 infection regardless of affinity for ligand; however, only signaling by the highest affinity receptor facilitated HIV-1 expression. Activation of chimeric antigen receptors that had intermediate and low binding affinities did not support provirus transcription, suggesting that a minimal signal is required for optimal HIV-1 expression. In addition, strong signaling at the time of infection produced a latent population that was readily inducible, whereas latent cells generated in response to weaker signals were not easily reversed. Chromatin immunoprecipitation showed HIV-1 transcription was limited by transcriptional elongation and that robust signaling decreased the presence of negative elongation factor, a pausing factor, by more than 80%. These studies demonstrate that T cell signaling influences HIV-1 infection and the establishment of different subsets of latently infected cells, which may have implications for targeting the HIV-1 reservoir.
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Affiliation(s)
- Matthew Gagne
- Department of Microbiology, Boston University School of Medicine, Boston, MA, United States of America
| | - Daniel Michaels
- Department of Microbiology, Boston University School of Medicine, Boston, MA, United States of America
- Department of Medicine, Section of Infectious Diseases, Boston University Medical Center, Boston, MA, United States of America
| | - Gillian M. Schiralli Lester
- Department of Pediatrics, Neonatology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Suryaram Gummuluru
- Department of Microbiology, Boston University School of Medicine, Boston, MA, United States of America
| | - Wilson W. Wong
- Department of Biomedical Engineering, Boston University, Boston, MA, United States of America
- Biological Design Center, Boston University, Boston, MA, United States of America
| | - Andrew J. Henderson
- Department of Microbiology, Boston University School of Medicine, Boston, MA, United States of America
- Department of Medicine, Section of Infectious Diseases, Boston University Medical Center, Boston, MA, United States of America
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12
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Abstract
Current primary cell models for HIV latency correlate poorly with the reactivation behavior of patient cells. We have developed a new model, called QUECEL, which generates a large and homogenous population of latently infected CD4+ memory cells. By purifying HIV-infected cells and inducing cell quiescence with a defined cocktail of cytokines, we have eliminated the largest problems with previous primary cell models of HIV latency: variable infection levels, ill-defined polarization states, and inefficient shutdown of cellular transcription. Latency reversal in the QUECEL model by a wide range of agents correlates strongly with RNA induction in patient samples. This scalable and highly reproducible model of HIV latency will permit detailed analysis of cellular mechanisms controlling HIV latency and reactivation. The latent HIV reservoir is generated following HIV infection of activated effector CD4 T cells, which then transition to a memory phenotype. Here, we describe an ex vivo method, called QUECEL (quiescent effector cell latency), that mimics this process efficiently and allows production of large numbers of latently infected CD4+ T cells. Naïve CD4+ T cells were polarized into the four major T cell subsets (Th1, Th2, Th17, and Treg) and subsequently infected with a single-round reporter virus which expressed GFP/CD8a. The infected cells were purified and coerced into quiescence using a defined cocktail of cytokines, including tumor growth factor beta, interleukin-10 (IL-10), and IL-8, producing a homogeneous population of latently infected cells. Flow cytometry and transcriptome sequencing (RNA-Seq) demonstrated that the cells maintained the correct polarization phenotypes and had withdrawn from the cell cycle. Key pathways and gene sets enriched during transition from quiescence to reactivation include E2F targets, G2M checkpoint, estrogen response late gene expression, and c-myc targets. Reactivation of HIV by latency-reversing agents (LRAs) closely mimics RNA induction profiles seen in cells from well-suppressed HIV patient samples using the envelope detection of in vitro transcription sequencing (EDITS) assay. Since homogeneous populations of latently infected cells can be recovered, the QUECEL model has an excellent signal-to-noise ratio and has been extremely consistent and reproducible in numerous experiments performed during the last 4 years. The ease, efficiency, and accuracy of the mimicking of physiological conditions make the QUECEL model a robust and reproducible tool to study the molecular mechanisms underlying HIV latency.
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13
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Couturier J, Orozco AF, Liu H, Budhiraja S, Siwak EB, Nehete PN, Sastry KJ, Rice AP, Lewis DE. Regulation of cyclin T1 during HIV replication and latency establishment in human memory CD4 T cells. Virol J 2019; 16:22. [PMID: 30786885 PMCID: PMC6381639 DOI: 10.1186/s12985-019-1128-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 02/12/2019] [Indexed: 01/30/2023] Open
Abstract
Background The regulatory cyclin, Cyclin T1 (CycT1), is a host factor essential for HIV-1 replication in CD4 T cells and macrophages. The importance of CycT1 and the Positive Transcription Elongation Factor b (P-TEFb) complex for HIV replication is well-established, but regulation of CycT1 expression and protein levels during HIV replication and latency establishment in CD4 T cells is less characterized. Methods To better define the regulation of CycT1 levels during HIV replication in CD4 T cells, multiparameter flow cytometry was utilized to study the interaction between HIV replication (intracellular p24) and CycT1 of human peripheral blood memory CD4 T cells infected with HIV in vitro. CycT1 was further examined in CD4 T cells of human lymph nodes. Results In activated (CD3+CD28 costimulation) uninfected blood memory CD4 T cells, CycT1 was most significantly upregulated in maximally activated (CD69+CD25+ and HLA.DR+CD38+) cells. In memory CD4 T cells infected with HIV in vitro, two distinct infected populations of p24+CycT1+ and p24+CycT1- cells were observed during 7 days infection, suggestive of different phases of productive HIV replication and subsequent latency establishment. Intriguingly, p24+CycT1- cells were the predominant infected population in activated CD4 T cells, raising the possibility that productively infected cells may transition into latency subsequent to CycT1 downregulation. Additionally, when comparing infected p24+ cells to bystander uninfected p24- cells (after bulk HIV infections), HIV replication significantly increased T cell activation (CD69, CD25, HLA.DR, CD38, and Ki67) without concomitantly increasing CycT1 protein levels, possibly due to hijacking of P-TEFb by the viral Tat protein. Lastly, CycT1 was constitutively expressed at higher levels in lymph node CD4 T cells compared to blood T cells, potentially enhancing latency generation in lymphoid tissues. Conclusions CycT1 is most highly upregulated in maximally activated memory CD4 T cells as expected, but may become less associated with T cell activation during HIV replication. The progression into latency may further be predicated by substantial generation of p24+CycT1- cells during HIV replication. Electronic supplementary material The online version of this article (10.1186/s12985-019-1128-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jacob Couturier
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Aaron F Orozco
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Hongbing Liu
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Sona Budhiraja
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Edward B Siwak
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Pramod N Nehete
- Department of Veterinary Sciences, The University of Texas MD Anderson Cancer Center, Bastrop, TX, USA
| | - K Jagannadha Sastry
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Andrew P Rice
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Dorothy E Lewis
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
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14
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Zhang H, Pandey S, Travers M, Sun H, Morton G, Madzo J, Chung W, Khowsathit J, Perez-Leal O, Barrero CA, Merali C, Okamoto Y, Sato T, Pan J, Garriga J, Bhanu NV, Simithy J, Patel B, Huang J, Raynal NJM, Garcia BA, Jacobson MA, Kadoch C, Merali S, Zhang Y, Childers W, Abou-Gharbia M, Karanicolas J, Baylin SB, Zahnow CA, Jelinek J, Graña X, Issa JPJ. Targeting CDK9 Reactivates Epigenetically Silenced Genes in Cancer. Cell 2018; 175:1244-1258.e26. [PMID: 30454645 PMCID: PMC6247954 DOI: 10.1016/j.cell.2018.09.051] [Citation(s) in RCA: 153] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 09/19/2018] [Accepted: 09/24/2018] [Indexed: 12/31/2022]
Abstract
Cyclin-dependent kinase 9 (CDK9) promotes transcriptional elongation through RNAPII pause release. We now report that CDK9 is also essential for maintaining gene silencing at heterochromatic loci. Through a live cell drug screen with genetic confirmation, we discovered that CDK9 inhibition reactivates epigenetically silenced genes in cancer, leading to restored tumor suppressor gene expression, cell differentiation, and activation of endogenous retrovirus genes. CDK9 inhibition dephosphorylates the SWI/SNF protein BRG1, which contributes to gene reactivation. By optimization through gene expression, we developed a highly selective CDK9 inhibitor (MC180295, IC50 = 5 nM) that has broad anti-cancer activity in vitro and is effective in in vivo cancer models. Additionally, CDK9 inhibition sensitizes to the immune checkpoint inhibitor α-PD-1 in vivo, making it an excellent target for epigenetic therapy of cancer.
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Affiliation(s)
- Hanghang Zhang
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Somnath Pandey
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Meghan Travers
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21231, USA
| | - Hongxing Sun
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - George Morton
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Jozef Madzo
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Woonbok Chung
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Jittasak Khowsathit
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA; Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
| | - Oscar Perez-Leal
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Carlos A Barrero
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Carmen Merali
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Yasuyuki Okamoto
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Takahiro Sato
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Joshua Pan
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA
| | - Judit Garriga
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Natarajan V Bhanu
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Johayra Simithy
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Bela Patel
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Jian Huang
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Noël J-M Raynal
- Département de pharmacologie et physiologie, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Benjamin A Garcia
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marlene A Jacobson
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Cigall Kadoch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA
| | - Salim Merali
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Yi Zhang
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Wayne Childers
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Magid Abou-Gharbia
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - John Karanicolas
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Stephen B Baylin
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21231, USA
| | - Cynthia A Zahnow
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21231, USA
| | - Jaroslav Jelinek
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Xavier Graña
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Jean-Pierre J Issa
- Fels Institute for Cancer Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA.
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15
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Machado Andrade V, Stevenson M. Host and Viral Factors Influencing Interplay between the Macrophage and HIV-1. J Neuroimmune Pharmacol 2018; 14:33-43. [PMID: 29995208 DOI: 10.1007/s11481-018-9795-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 06/26/2018] [Indexed: 12/29/2022]
Abstract
HIV-1 persists in cellular reservoirs that cannot be eliminated by antiretroviral therapy (ART). The major reservoir in infected individuals on effective ART is composed of resting memory CD4+ T cells that harbor proviral cDNA, and undergo a state of latency in which viral gene expression is minimal to absent. The CD4+ T cell reservoir has been extensively characterized. However, other HIV-1-permissive cells may contribute to HIV-1 persistence. Lentiviruses have a long recognized association with macrophages. However, the role, if any, played by macrophages in HIV-1 persistence is not well understood. Macrophages are resistant to cell death upon HIV-1 infection, and can survive for long periods of time, making them ideal host cells in which the virus might persist. Studying macrophages is challenging, as these cells reside in nearly all tissues. Moreover, detecting viral DNA or RNA in macrophages does not necessarily indicate that these cells will produce replication-competent viral particles. Currently, the gold standard assay to detect cellular reservoirs is the ex vivo quantitative viral outgrowth assay (QVOA), which requires a patient blood draw. However, macrophages reside deep within tissues that are inaccessible in living subjects, such as the central nervous system (CNS). Therefore, tools other than QVOA must be developed to identify cellular reservoirs that reside in the tissues. In this review, we will focus on the main aspects involved in HIV-1 persistence, including the molecular mechanisms of viral evasion, the main cell types responsible for harboring persistent HIV-1 and the tissue compartments that are likely to be reservoirs for HIV-1.
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Affiliation(s)
- Viviane Machado Andrade
- Molecular Cell and Developmental Biology, Miller School of Medicine, University of Miami, Miami, FL, 33136, USA.
| | - Mario Stevenson
- Division of Infectious Diseases, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, 33136, USA
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16
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Li X, Xu JX, Jia XS, Li WY, Han YC, Wang EH, Li F. Dormancy activation mechanism of tracheal stem cells. Oncotarget 2018; 7:23730-9. [PMID: 27009861 PMCID: PMC5029659 DOI: 10.18632/oncotarget.8179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/02/2016] [Indexed: 01/23/2023] Open
Abstract
Accurate markers and molecular mechanisms of stem cell dormancy and activation are poorly understood. In this study, the anti-cancer drug, 5-fluorouracil, was used to selectively kill proliferating cells of human bronchial epithelial (HBE) cell line. This method can enrich and purify stem cell population. The dormant versus active status of stem cells was determined by phosphorylation of RNAp II Ser2. The surviving stem cells were cultured to form stem cell spheres expressing stem cell markers and transplanted into nude mice to form a teratoma. The results demonstrated the properties of stem cells and potential for multi-directional differentiation. Bisulfite sequencing polymerase chain reaction showed that demethylation of the Sox2 promoter by 5-FU resulted in Sox2 expression in the dormant stem cells. This study shows that the dormancy and activation of HBE stem cells is closely related to epigenetic modification.
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Affiliation(s)
- Xin Li
- Department of Physiology, College of Life Science and Biopharmaceutics of Shenyang Pharmaceutical University, Shenyang, China.,Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China.,Department of Pathology, First Affiliated Hospital of China Medical University, Shenyang, China
| | - Jing-Xian Xu
- Department of Ophthalmology, The 4th Affiliated Hospital, Eye Institute, China Medical University, The Key Laboratory of Lens Research, Shenyang, China
| | - Xin-Shan Jia
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China.,Department of Pathology, First Affiliated Hospital of China Medical University, Shenyang, China
| | - Wen-Ya Li
- Department of Thoracic Surgery, The First Affiliated Hospital, China Medical University, Shenyang, China
| | - Yi-Chen Han
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China.,Department of Pathology, First Affiliated Hospital of China Medical University, Shenyang, China
| | - En-Hua Wang
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China.,Department of Pathology, First Affiliated Hospital of China Medical University, Shenyang, China
| | - Fang Li
- IVF Michigan, Bloomfield Hills, MI, USA
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17
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SUN2 Silencing Impairs CD4 T Cell Proliferation and Alters Sensitivity to HIV-1 Infection Independently of Cyclophilin A. J Virol 2017; 91:JVI.02303-16. [PMID: 28077629 DOI: 10.1128/jvi.02303-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 12/29/2016] [Indexed: 11/20/2022] Open
Abstract
Linker of nucleoskeleton and cytoskeleton (LINC) complexes connect the nucleus to the cytoskeleton in eukaryotic cells. We previously reported that the overexpression of SUN2, an inner nuclear membrane protein and LINC complex component, inhibits HIV infection between the steps of reverse transcription and nuclear import in a capsid-specific manner. We also reported that SUN2 silencing does not modulate HIV infection in several cell lines. Silencing of SUN2 was recently reported to decrease HIV infection of CD4 T cells, an effect which was suggested to result from modulation of cyclophilin A (CypA)-dependent steps of HIV infection. We confirm here that HIV infection of primary CD4 T cells is compromised in the absence of endogenous SUN2, and we extend these findings to additional viral strains. However, we find that CypA is not required for the decreased infection observed in SUN2-silenced cells and, conversely, that endogenous SUN2 is not required for the well-documented positive modulation of HIV infection by CypA. In contrast, CD4 T cells lacking SUN2 exhibit a considerable defect in proliferative capacity and display reduced levels of activation markers and decreased viability. Additionally, SUN2-silenced CD4 T cells that become infected support reduced levels of viral protein expression. Our results demonstrate that SUN2 is required for the optimal activation and proliferation of primary CD4 T cells and suggest that the disruption of these processes explains the contribution of endogenous SUN2 to HIV infection in primary lymphocytes.IMPORTANCE Linker of nucleoskeleton and cytoskeleton (LINC) complexes connect the nucleus to the cytoskeleton. We previously reported that the overexpression of the LINC complex protein SUN2 inhibits HIV infection by targeting the viral capsid and blocking infection before the virus enters the nucleus. A recent report showed that the depletion of endogenous SUN2 in primary CD4 T cells results in decreased HIV infection and that this involves cyclophilin A (CypA), a host protein that interacts with the capsid of HIV to promote infection. We confirm that HIV infection is reduced in CD4 T cells lacking SUN2, but we find no role for CypA. Instead, SUN2 silencing results in CD4 T cells with decreased viability and much lower proliferation rates. Our results show that SUN2 is required for optimal CD4 T cell activation and proliferation and explain the reduced level of HIV infection in the absence of SUN2.
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18
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Han Y, Zhao S, Gong Y, Hou G, Li X, Li L. Serum cyclin-dependent kinase 9 is a potential biomarker of atherosclerotic inflammation. Oncotarget 2016; 7:1854-62. [PMID: 26636538 PMCID: PMC4811502 DOI: 10.18632/oncotarget.6443] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 11/16/2015] [Indexed: 11/25/2022] Open
Abstract
Atherosclerotic coronary artery disease (CAD) is one of the most prevalent diseases worldwide. Atherosclerosis was considered to be the single most important contributor to CAD. In this study, a distinct serum protein expression pattern in CAD patients was demonstrated by proteomic analysis with two-dimensional gel electrophoresis coupled with mass spectrometry. In particular, CDK9 was found to be highly elevated in serum, monocytes and artery plaque samples of CAD patients. Furthermore, there was high infiltration of CD14+ monocytes/macrophages within artery plaques correlated with the expression of CDK9. Moreover, Flavopiridol (CDK9 inhibitor) could inhibit THP-1 cell (monocytic acute leukemia cell line) proliferation by targeting CDK9. Altogether, These findings indicate that CDK9 represent an important role for inflammation in the pathogenesis of atherosclerosis. It may be a potential biomarker of atherosclerotic inflammation and offer insights into the pathophysiology and targeted therapy for atherosclerotic CAD.
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Affiliation(s)
- Yeming Han
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Department of of Cardiology, Qilu Hospital, Shandong University, Jinan, Shandong, 250012, China
| | - Shanshan Zhao
- Laboratory of Experimental Teratology, Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Yaoqin Gong
- Laboratory of Experimental Teratology, Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Department of Genetics, School of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Guihua Hou
- Laboratory of Experimental Teratology, Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Xi Li
- Laboratory of Experimental Teratology, Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Department of Genetics, School of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Li Li
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Department of of Cardiology, Qilu Hospital, Shandong University, Jinan, Shandong, 250012, China
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De Luca A, Tosolini A, Russo P, Severino A, Baldi A, De Luca L, Cavallotti I, Baldi F, Giordano A, Testa JR, Paggi MG. Cyclin T2A Gene Maps on Human Chromosome 2q21. J Histochem Cytochem 2016; 49:693-8. [PMID: 11373316 DOI: 10.1177/002215540104900603] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cyclin T2a was recently identified as one of the regulatory subunits of the cdk–cyclin complex P-TEFb, the most studied positive factor in the regulation of transcription elongation. By fluorescent in situ hybridization (FISH), the gene codifying for cyclin T2a has been mapped on human chromosome 2q21. This locus also has been linked to different forms of myopathy. By use of a new specific antiserum raised against cyclin T2a, the immunohistochemical pattern of expression of cyclin T2a in human tissues has been examined and compared to that of cyclin T1, described in the previous report. The observation that immunohistochemical expression of cyclin T2a was high in skeletal muscle cells, whereas it was undetectable in two cases of centronuclear myopathy, together with its chromosomal location, suggests an involvement of the cdk9–cyclin T2a complex in this disease.
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Affiliation(s)
- A De Luca
- Laboratory of Cell Metabolism and Pharmacokinetics, CRS, Regina Elena Cancer Institute, Rome, Italy
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20
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Lin LF, Jin JS, Chen JC, Huang CC, Sheu JH, Chen W, Tsao TY, Hsu CW. Positive cyclin T expression as a favorable prognostic factor in treating gastric gastrointestinal stromal tumors. Mol Clin Oncol 2016; 4:971-975. [PMID: 27284431 DOI: 10.3892/mco.2016.835] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 10/26/2015] [Indexed: 12/13/2022] Open
Abstract
Positive transcriptional elongation factor b (P-TEFb) contains the catalytic subunit cyclin-dependent kinase 9 (Cdk9) and the regulatory subunit cyclin T. Cyclin T1 and Cdk9 are the key factors of the PTEFb pathways and are overexpressed in the human head and neck carcinoma cell line. However, there have been limited studies regarding the role of cyclin T1 and Cdk9 in gastric gastrointestinal stromal tumors (GISTs). The aim of the present study was to assess the association between cyclin T1 and Cdk9 and their clinical significance in gastric GISTs. A total of 30 gastric GIST patients who underwent either laparoscopic or laparotomic partial gastrectomy were enrolled in the study. The surgical tissue slides were stained with Cdk9 and cyclin T1 antibodies, and the immunohistochemistry scores and disease-free survival (DFS) were analyzed. Ten patients were cyclin T1-positive, and 20 were negative. All 11 patients with recurrent tumors or distant metastases were cyclin T1-negative patients. Old age, large tumor size, a high Ki67 IHC staining score, high mitotic count and negative cyclin T1 staining revealed a worse clinical outcome in univariate analysis. By contrast, the Cdk9 score was not associated with clinical parameters. The Kaplan-Meier survival curve illustrated that the DFS rate of the patients with negative cyclin T1 staining was significantly lower than that of the patients with positive cyclin T1 staining. Positive expression of cyclin T1 was a good prognostic factor in patients with gastric GISTs.
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Affiliation(s)
- Lien-Fu Lin
- Division of Gastroenterology, Department of Internal Medicine, Tungs' Taichung MetroHarbor Hospital, Taichung 435, Taiwan R.O.C
| | - Jong-Shiaw Jin
- Department of Pathology, Tungs' Taichung MetroHarbor Hospital, Taichung 435, Taiwan R.O.C
| | - Jui-Chang Chen
- Department of Applied Chemistry, National Chia-Yi University, Chia-Yi 600, Taiwan R.O.C
| | - Chia-Chi Huang
- Center of Nano Bio-Detection, National Chung Cheng University Chia-Yi, Chia-Yi 621, Taiwan R.O.C
| | - Jeng-Horng Sheu
- Department of Applied Chemistry, National Chia-Yi University, Chia-Yi 600, Taiwan R.O.C
| | - Wenlung Chen
- Department of Applied Chemistry, National Chia-Yi University, Chia-Yi 600, Taiwan R.O.C
| | - Tang-Yi Tsao
- Department of Pathology, Tungs' Taichung MetroHarbor Hospital, Taichung 435, Taiwan R.O.C
| | - Chih-Wei Hsu
- Department of Applied Chemistry, National Chia-Yi University, Chia-Yi 600, Taiwan R.O.C.; Division of General Surgery, Department of Surgery, Tungs' Taichung MetroHarbor Hospital, Taichung 435, Taiwan R.O.C
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Yeh YY, Chen R, Hessler J, Mahoney E, Lehman AM, Heerema NA, Grever MR, Plunkett W, Byrd JC, Johnson AJ. Up-regulation of CDK9 kinase activity and Mcl-1 stability contributes to the acquired resistance to cyclin-dependent kinase inhibitors in leukemia. Oncotarget 2015; 6:2667-79. [PMID: 25596730 PMCID: PMC4413609 DOI: 10.18632/oncotarget.2096] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 06/11/2014] [Indexed: 11/25/2022] Open
Abstract
Flavopiridol is a small molecule inhibitor of cyclin-dependent kinases (CDK) known to impair global transcription via inactivation of positive transcription elongation factor b. It has been demonstrated to have significant activity predominantly in chronic lymphocytic leukemia and acute myeloid leukemia in phase I/II clinical trials while other similar CDK inhibitors are vigorously being pursued in pre-clinical and clinical studies. Although flavopiridol is a potent therapeutic agent against blood diseases, some patients still have primary or acquired resistance throughout their clinical course. Considering the limited knowledge of resistance mechanisms of flavopiridol, we investigated the potential mechanisms of resistance to flavopiridol in a cell line system, which gradually acquired resistance to flavopiridol in vitro, and then confirmed the mechanism in patient samples. Herein, we present that this resistant cell line developed resistance through up-regulation of phosphorylation of RNA polymerase II C-terminal domain, activation of CDK9 kinase activity, and prolonged Mcl-1 stability to counter flavopiridol's drug actions. Further analyses suggest MAPK/ERK activation-mediated Mcl-1 stabilization contributes to the resistance and knockdown of Mcl-1 in part restores sensitivity to flavopiridol-induced cytotoxicity. Altogether, these findings demonstrate that CDK9 is the most relevant target of flavopiridol and provide avenues to improve the therapeutic strategies in blood malignancies.
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Affiliation(s)
- Yuh-Ying Yeh
- Division of Hematology, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA
| | - Rong Chen
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Joshua Hessler
- Division of Hematology, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA
| | - Emilia Mahoney
- Division of Hematology, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA
| | - Amy M Lehman
- Center for Biostatistics, The Ohio State University, Columbus, Ohio, USA
| | - Nyla A Heerema
- Department of Pathology, The Ohio State University, Columbus, Ohio, USA
| | - Michael R Grever
- Division of Hematology, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA
| | - William Plunkett
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - John C Byrd
- Division of Hematology, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA.,Division of Medicinal Chemistry, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Amy J Johnson
- Division of Hematology, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA.,Division of Medicinal Chemistry, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
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22
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Jin JS, Lin LF, Chen JC, Huang CC, Sheu JH, Chen W, Tsao TY, Hsu CW. Increased cyclin T1 expression as a favorable prognostic factor in treating gastric adenocarcinoma. Oncol Lett 2015; 10:3712-3718. [PMID: 26788195 DOI: 10.3892/ol.2015.3749] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 08/17/2015] [Indexed: 12/11/2022] Open
Abstract
The expression of cyclin A, B1, D1 and E in gastric adenocarcinoma is known to be associated with clinical outcome. However, few studies have investigated the role of cyclin T1 and cyclin-dependent kinase 9 (CDK9) in gastric adenocarcinoma. Therefore, this study assessed the clinical significance of cyclin T1 and CDK9 expression in gastric adenocarcinoma. A total of 39 gastric adenocarcinoma patients received either radical total or distal gastrectomy in this study. Surgical tissue slides were stained with CDK9 and cyclin T1 antibodies, and immunohistochemistry scores and disease-free survival (DFS) rates were analyzed. Among the 19 patients with tumor-recurrent or distant metastasis, 16 were recorded as exhibiting low expression of cyclin T1. The remaining three patients exhibited high expression of the antibody. The results of patients with a higher T stage, N stage and tumor grade were less favorable. For patients with adenocarcinoma, the percentage of tissue slides stained with cyclin T1 was significantly higher than for those with normal stomach epithelia. The DFS rates of patients with low expression of cyclin T1 were significantly associated with poorer DFS rates. In conclusion, high expression of cyclin T1 is a favorable prognostic factor in treating patients with stomach adenocarcinoma.
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Affiliation(s)
- Jong-Shiaw Jin
- Department of Pathology, Department of Internal Medicine, Tungs' Taichung Metro Harbor Hospital, Taichung 43503, Taiwan, R.O.C
| | - Lien-Fu Lin
- Division of Gastroenterology, Department of Internal Medicine, Tungs' Taichung Metro Harbor Hospital, Taichung 43503, Taiwan, R.O.C
| | - Jui-Chang Chen
- Department of Applied Chemistry, National Chiayi University, Chia-Yi 60004, Taiwan, R.O.C
| | - Chia-Chi Huang
- Center of Nano Bio-detection, National Chung Cheng University, Chia-Yi 62102, Taiwan, R.O.C
| | - Jeng-Horng Sheu
- Department of Applied Chemistry, National Chiayi University, Chia-Yi 60004, Taiwan, R.O.C
| | - Wenlung Chen
- Department of Applied Chemistry, National Chiayi University, Chia-Yi 60004, Taiwan, R.O.C
| | - Tang-Yi Tsao
- Division of General Surgery, Department of Surgery, Tungs' Taichung Metro Harbor Hospital, Taichung 43503, Taiwan, R.O.C
| | - Chih-Wei Hsu
- Department of Applied Chemistry, National Chiayi University, Chia-Yi 60004, Taiwan, R.O.C.; Division of General Surgery, Department of Surgery, Tungs' Taichung Metro Harbor Hospital, Taichung 43503, Taiwan, R.O.C
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23
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Selective HDAC inhibition for the disruption of latent HIV-1 infection. PLoS One 2014; 9:e102684. [PMID: 25136952 PMCID: PMC4138023 DOI: 10.1371/journal.pone.0102684] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 06/23/2014] [Indexed: 11/30/2022] Open
Abstract
Selective histone deacetylase (HDAC) inhibitors have emerged as a potential anti-latency therapy for persistent human immunodeficiency virus type 1 (HIV-1) infection. We utilized a combination of small molecule inhibitors and short hairpin (sh)RNA-mediated gene knockdown strategies to delineate the key HDAC(s) to be targeted for selective induction of latent HIV-1 expression. Individual depletion of HDAC3 significantly induced expression from the HIV-1 promoter in the 2D10 latency cell line model. However, depletion of HDAC1 or −2 alone or in combination did not significantly induce HIV-1 expression. Co-depletion of HDAC2 and −3 resulted in a significant increase in expression from the HIV-1 promoter. Furthermore, concurrent knockdown of HDAC1, −2, and −3 resulted in a significant increase in expression from the HIV-1 promoter. Using small molecule HDAC inhibitors of differing selectivity to ablate the residual HDAC activity that remained after (sh)RNA depletion, the effect of depletion of HDAC3 was further enhanced. Enzymatic inhibition of HDAC3 with the selective small-molecule inhibitor BRD3308 activated HIV-1 transcription in the 2D10 cell line. Furthermore, ex vivo exposure to BRD3308 induced outgrowth of HIV-1 from resting CD4+ T cells isolated from antiretroviral-treated, aviremic HIV+ patients. Taken together these findings suggest that HDAC3 is an essential target to disrupt HIV-1 latency, and inhibition of HDAC2 may also contribute to the effort to purge and eradicate latent HIV-1 infection.
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Negative elongation factor is required for the maintenance of proviral latency but does not induce promoter-proximal pausing of RNA polymerase II on the HIV long terminal repeat. Mol Cell Biol 2014; 34:1911-28. [PMID: 24636995 DOI: 10.1128/mcb.01013-13] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The role of the negative elongation factor (NELF) in maintaining HIV latency was investigated following small hairpin RNA (shRNA) knockdown of the NELF-E subunit, a condition that induced high levels of proviral transcription in latently infected Jurkat T cells. Chromatin immunoprecipitation (ChIP) assays showed that latent proviruses accumulate RNA polymerase II (RNAP II) on the 5' long terminal repeat (LTR) but not on the 3' LTR. NELF colocalizes with RNAP II, and its level increases following proviral induction. RNAP II pause sites on the HIV provirus were mapped to high resolution by ChIP with high-throughput sequencing (ChIP-Seq). Like cellular promoters, RNAP II accumulates at around position +30, but HIV also shows additional pausing at +90, which is immediately downstream of a transactivation response (TAR) element and other distal sites on the HIV LTR. Following NELF-E knockdown or tumor necrosis factor alpha (TNF-α) stimulation, promoter-proximal RNAP II levels increase up to 3-fold, and there is a dramatic increase in RNAP II levels within the HIV genome. These data support a kinetic model for proviral transcription based on continuous replacement of paused RNAP II during both latency and productive transcription. In contrast to most cellular genes, HIV is highly activated by the combined effects of NELF-E depletion and activation of initiation by TNF-α, suggesting that opportunities exist to selectively activate latent HIV proviruses.
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25
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Affiliation(s)
- Jiannan Guo
- Biochemistry Department, University of Iowa , Iowa City, Iowa 52242, United States
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26
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Deregulations in the cyclin-dependent kinase-9-related pathway in cancer: implications for drug discovery and development. ISRN ONCOLOGY 2013; 2013:305371. [PMID: 23840966 PMCID: PMC3690251 DOI: 10.1155/2013/305371] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 05/19/2013] [Indexed: 12/21/2022]
Abstract
The CDK9-related pathway is an important regulator of mammalian cell biology and is also involved in the replication cycle of several viruses, including the human immunodeficiency virus type 1. CDK9 is present in two isoforms termed CDK9-42 and CDK9-55 that bind noncovalently type T cyclins and cyclin K. This association forms a heterodimer, where CDK9 carries the enzymatic site and the cyclin partner functions as a regulatory subunit. This heterodimer is the main component of the positive transcription elongation factor b, which stabilizes RNA elongation via phosphorylation of the RNA pol II carboxyl terminal domain. Abnormal activities in the CDK9-related pathway were observed in human malignancies and cardiac hypertrophies. Thus, the elucidation of the CDK9 pathway deregulations may provide useful insights into the pathogenesis and progression of human malignancies, cardiac hypertrophy, AIDS and other viral-related maladies. These studies may lead to the improvement of kinase inhibitors for the treatment of the previously mentioned pathological conditions. This review describes the CDK9-related pathway deregulations in malignancies and the development of kinase inhibitors in cancer therapy, which can be classified into three categories: antagonists that block the ATP binding site of the catalytic domain, allosteric inhibitors, and small molecules that disrupt protein-protein interactions.
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27
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Pan X, Baldauf HM, Keppler OT, Fackler OT. Restrictions to HIV-1 replication in resting CD4+ T lymphocytes. Cell Res 2013; 23:876-85. [PMID: 23732522 PMCID: PMC3698640 DOI: 10.1038/cr.2013.74] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
CD4+ T lymphocytes represent the main target cell population of human immunodeficiency virus (HIV). In an activated state, CD4+ T cells residing in lymphoid organs are a major reservoir of ongoing HIV-1 replication in infected individuals. In contrast, resting CD4+ T cells are highly resistant to productive HIV-1 infection, yet are massively depleted during disease progression and represent a substantial latent reservoir for the virus in vivo. Barriers preventing replication of HIV-1 in resting CD4+ T cells include a rigid layer of cortical actin and, early after HIV-1 entry, a block that limits reverse transcription of incoming viral RNA genomes. Defining the molecular bases of these restrictions has remained one of the central open questions in HIV research. Recent advances unraveled mechanisms by which HIV-1 bypasses the entry block and established the host cell restriction factor SAMHD1, a deoxynucleoside triphosphate triphosphohydrolase, as a central determinant of the cellular restriction to HIV-1 reverse transcription in resting CD4+ T cells. This review summarizes our current molecular and pathophysiological understanding of the multi-faceted interactions of HIV-1 with resting CD4+ T lymphocytes.
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Affiliation(s)
- Xiaoyu Pan
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
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28
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Casimiro MC, Crosariol M, Loro E, Li Z, Pestell RG. Cyclins and cell cycle control in cancer and disease. Genes Cancer 2013; 3:649-57. [PMID: 23634253 DOI: 10.1177/1947601913479022] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cyclin D1 overexpression is found in more than 50% of human breast cancers and causes mammary cancer in transgenic mice. Dysregulation of cyclin D1 gene expression or function contributes to the loss of normal cell cycle control during tumorigenesis. Recent studies have demonstrated that cyclin D1 conducts additional specific functions to regulate gene expression in the context of local chromatin, promote cellular migration, and promote chromosomal instability. It is anticipated that these additional functions contribute to the pathology associated with dysregulated cyclin D1 abundance. This article discusses evidence that examines the functional roles that cyclin D1 may play in cancer with an emphasis on other cyclin family members that also may contribute to cancer and disease in a similar fashion.
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29
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Gao G, Wu X, Zhou J, He M, He JJ, Guo D. Inhibition of HIV-1 transcription and replication by a newly identified cyclin T1 splice variant. J Biol Chem 2013; 288:14297-14309. [PMID: 23569210 DOI: 10.1074/jbc.m112.438465] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A variety of cellular factors participates in the HIV-1 life cycle. Among them is the well characterized cyclin T1 (CYCT1). CycT1 binds to cyclin-dependent kinase 9 (CDK9) and forms the positive transcription elongation factor-b (P-TEFb). P-TEFb is then recruited by HIV-1 TAT to the HIV-1 long terminal repeat (LTR) promoter and subsequently leads to phosphorylation of the C-terminal domain of RNA polymerase II (pol II), enhanced processivity of pol II, and transcription of a full-length HIV-1 RNA. In this study, we report the identification of a new CYCT1 splice variant, designated as CYCT1b, and accordingly we renamed CYCT1 as CYCT1a. CYCT1b was detected in several cell lines, including primary human CD4 T cells, and its expression was subject to cell cycle regulation. Similar to CYCT1a, CYCT1b was primarily localized in the nucleus. CYCT1b expression was found to be inversely correlated with HIV-1 gene expression and replication. This inverse correlation appeared to involve TAT transactivation, CDK9 binding, and subsequent recruitment of P-TEFb to the HIV-1 LTR promoter and pol II C-terminal domain phosphorylation. In agreement with these findings, CYCT1b expression led to direct inhibition of TAT-transactivated transcription of the HIV-1 LTR promoter. Taken together, these results show that the newly identified CYCT1b splice variant inhibits HIV-1 transcription and may provide new clues for the development of anti-HIV strategies.
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Affiliation(s)
- Guozhen Gao
- State Key Laboratory of Virology and Modern Virology Research Center, Wuhan University College of Life Sciences, 430072 Wuhan, China; Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Xiaoyun Wu
- State Key Laboratory of Virology and Modern Virology Research Center, Wuhan University College of Life Sciences, 430072 Wuhan, China
| | - Jieqiong Zhou
- State Key Laboratory of Virology and Modern Virology Research Center, Wuhan University College of Life Sciences, 430072 Wuhan, China
| | - Mingfeng He
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Johnny J He
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana 46202; Center for AIDS Research, Indiana University School of Medicine, Indianapolis, Indiana 46202; University of North Texas Health Science Center, Fort Worth, Texas 76107.
| | - Deyin Guo
- State Key Laboratory of Virology and Modern Virology Research Center, Wuhan University College of Life Sciences, 430072 Wuhan, China; Institute of Medical Virology, Wuhan University School of Medicine, 430071 Wuhan, China.
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Dhamija N, Rawat P, Mitra D. Epigenetic regulation of HIV-1 persistence and evolving strategies for virus eradication. Subcell Biochem 2013; 61:479-505. [PMID: 23150264 DOI: 10.1007/978-94-007-4525-4_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Despite the intense effort put by researchers globally to understand Human Immunodeficiency Virus (HIV-1) pathogenesis since its discovery 30 years ago, the acquired knowledge till date is not good enough to eradicate HIV-1 from an infected individual. HIV-1 infects cells of the human immune system and integrates into the host cell genome thereby leading to persistent infection in these cells. Based on the activation status of the cells, the infection could be productive or result in latent infection. The current regimen used to treat HIV-1 infection in an AIDS patient includes combination of antiretroviral drugs called Highly Active Anti-Retroviral Therapy (HAART). A major challenge for the success of HAART has been these latent reservoirs of HIV which remain hidden and pose major hurdle for the eradication of virus. Combination of HAART therapy with simultaneous activation of latent reservoirs of HIV-1 seems to be the future of anti-retroviral therapy; however, this will require a much better understanding of the mechanisms and regulation of HIV-1 latency. In this chapter, we have tried to elaborate on HIV-1 latency, highlighting the strategies employed by the virus to ensure persistence in the host with specific focus on epigenetic regulation of latency. A complete understanding of HIV-1 latency will be extremely essential for ultimate eradication of HIV-1 from the human host.
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Affiliation(s)
- Neeru Dhamija
- National Centre for Cell Science, NCCS Complex, Pune University Campus, Ganeshkhind, Pune, 411007, India
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Cyclin T1 and CDK9 T-loop phosphorylation are downregulated during establishment of HIV-1 latency in primary resting memory CD4+ T cells. J Virol 2012; 87:1211-20. [PMID: 23152527 DOI: 10.1128/jvi.02413-12] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
P-TEFb, a cellular kinase composed of Cyclin T1 and CDK9, is essential for processive HIV-1 transcription. P-TEFb activity is dependent on phosphorylation of Thr186 in the CDK9 T loop. In resting CD4(+) T cells which are nonpermissive for HIV-1 replication, the levels of Cyclin T1 and T-loop-phosphorylated CDK9 are very low but increase significantly upon cellular activation. Little is known about how P-TEFb activity and expression are regulated in resting central memory CD4(+) T cells, one of the main reservoirs of latent HIV-1. We used an in vitro primary cell model of HIV-1 latency to show that P-TEFb availability in resting memory CD4(+) T cells is governed by the differential expression and phosphorylation of its subunits. This is in contrast to previous observations in dividing cells, where P-TEFb can be regulated by its sequestration in the 7SK RNP complex. We find that resting CD4(+) T cells, whether naïve or memory and independent of their infection status, have low levels of Cyclin T1 and T-loop-phosphorylated CDK9, which increase upon activation. We also show that the decrease in Cyclin T1 protein upon the acquisition of a memory phenotype is in part due to proteasome-mediated proteolysis and likely also to posttranscriptional downregulation by miR-150. We also found that HEXIM1 levels are very low in ex vivo- and in vitro-generated resting memory CD4(+) T cells, thus limiting the sequestration of P-TEFb in the 7SK RNP complex, indicating that this mechanism is unlikely to be a driver of viral latency in this cell type.
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Ramakrishnan R, Liu H, Donahue H, Malovannaya A, Qin J, Rice AP. Identification of novel CDK9 and Cyclin T1-associated protein complexes (CCAPs) whose siRNA depletion enhances HIV-1 Tat function. Retrovirology 2012; 9:90. [PMID: 23110726 PMCID: PMC3494656 DOI: 10.1186/1742-4690-9-90] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 10/05/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND HIV-1 Tat activates RNA Polymerase II (RNAP II) elongation of the integrated provirus by recruiting a protein kinase known as P-TEFb to TAR RNA at the 5' end of nascent viral transcripts. The catalytic core of P-TEFb contains CDK9 and Cyclin T1 (CCNT1). A human endogenous complexome has recently been described - the set of multi-protein complexes in HeLa cell nuclei. We mined this complexome data set and identified 12 distinct multi-protein complexes that contain both CDK9 and CCNT1. We have termed these complexes CCAPs for CDK9/CCNT1-associated protein complexes. Nine CCAPs are novel, while three were previously identified as Core P-TEFb, the 7SK snRNP, and the Super-Elongation Complex. We have investigated the role of five newly identified CCAPs in Tat function and viral gene expression. RESULTS We examined five CCAPs that contain: 1) PPP1R10/TOX3/WDR82; 2) TTF2; 3) TPR; 4) WRNIP1; 5) FBXO11/CUL1/SKP1. SiRNA depletions of protein subunits of the five CCAPs enhanced Tat activation of an integrated HIV-1 LTR-Luciferase reporter in TZM-bl cells. Using plasmid transfection assays in HeLa cells, we also found that siRNA depletions of TTF2, FBXO11, PPP1R10, WDR82, and TOX3 enhanced Tat activation of an HIV-1 LTR-luciferase reporter, but the depletions did not enhance expression of an NF-κB reporter plasmid with the exception of PPP1R10. We found no evidence that depletion of CCAPs perturbed the level of CDK9/CCNT1 in the 7SK snRNP. We also found that the combination of siRNA depletions of both TTF2 and FBXO11 sensitized a latent provirus in Jurkat cells to reactivation by sub-optimal amounts of αCD3/CD28 antibodies. CONCLUSIONS Our results identified five novel CDK9/CCNT1 complexes that are capable of negative regulation of HIV-1 Tat function and viral gene expression. Because siRNA depletions of CCAPs enhance Tat function, it is possible that these complexes reduce the level of CDK9 and CCNT1 available for Tat, similar to the negative regulation of Tat by the 7SK snRNP. Our results highlight the complexity in the biological functions of CDK9 and CCNT1.
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Affiliation(s)
- Rajesh Ramakrishnan
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, Texas, USA
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33
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Narayanan A, Sampey G, Van Duyne R, Guendel I, Kehn-Hall K, Roman J, Currer R, Galons H, Oumata N, Joseph B, Meijer L, Caputi M, Nekhai S, Kashanchi F. Use of ATP analogs to inhibit HIV-1 transcription. Virology 2012; 432:219-31. [PMID: 22771113 DOI: 10.1016/j.virol.2012.06.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 02/21/2012] [Accepted: 06/02/2012] [Indexed: 12/18/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) is the etiological agent of AIDS. Chronic persistent infection is an important reason for the presence of "latent cell populations" even after Anti-Retroviral Therapy (ART). We have analyzed the effect of ATP analogs in inhibiting cdk9/T1 complex in infected cells. A third generation drug named CR8#13 is an effective inhibitor of Tat activated transcription. Following drug treatment, we observed a decreased loading of cdk9 onto the HIV-1 DNA. We found multiple novel cdk9/T1 complexes present in infected and uninfected cells with one complex being unique to infected cells. This complex is sensitive to CR8#13 in kinase assays. Treatment of PBMC with CR8#13 does not kill infected cells as compared to Flavopiridol. Interestingly, there is a difference in sensitivity of various clades to these analogs. Collectively, these results point to targeting novel complexes for inhibition of cellular proteins that are unique to infected cells.
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Affiliation(s)
- Aarthi Narayanan
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA 20110, USA
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Urano E, Miyauchi K, Ichikawa R, Futahashi Y, Komano J. Regulation of cyclin T1 expression and function by an alternative splice variant that skips exon 7 and contains a premature termination codon. Gene 2012; 505:1-8. [PMID: 22692005 DOI: 10.1016/j.gene.2012.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/15/2012] [Accepted: 06/04/2012] [Indexed: 11/19/2022]
Abstract
Cyclin T1 (CCNT1), a gene containing nine exons, forms the positive transcription elongation factor b (P-TEFb) complex and regulates a wide variety of biological processes including transcription. We discovered a novel splice variant of CCNT1 that lacks exon 7 (dE7). RT-PCR analysis revealed that the dE7 transcript was detected in almost all tissues examined. The dE7/FL transcript ratio was high in quiescent peripheral blood mononuclear cells (PBMC) and in tissues poor in cell division; however, it was low in activated PBMC and in tissues with high cell proliferative potential. These results suggest that exon 7 skipping is linked to cell cycle progression. Increasing the dE7/FL transcript ratio resulted in the reduction of CCNT1 protein levels, indicating that the expression of CCNT1 protein is controlled by exon skipping. Exon 7 skipping yields a +1 frameshift at exon 8, which generates a premature termination codon (PTC). The dE7 transcript levels increased when cells were treated with the protein synthesis inhibitor cycloheximide (CHX) or a kinase inhibitor wortmannin (WORT), whilst the FL transcript levels were unchanged, suggesting that the dE7 transcript is a target of nonsense-mediated decay (NMD). Importantly, reduction of dE7 transcript by WORT correlated well with the decrement of CCNT1 protein expression. The dE7 transcript would produce an approximately 23kDa protein that covers approximately 70% of the cyclin box. The ectopically expressed dE7 protein physically interacted with CDK9 and competed with FL CCNT1 for CDK9, thus should act dominant-negatively on FL CCNT1. The replication of human immunodeficiency virus type 1 (HIV-1), heavily dependent on the CCNT1 function, was inhibited by dE7 protein through the attenuation of Tat/long terminal repeat (LTR)-driven transcription. Taken together, these results suggest that dE7 is a novel splice variant that regulates the expression and function of CCNT1.
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Affiliation(s)
- Emiko Urano
- AIDS Research Center, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
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35
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Abstract
Regulation of the elongation phase of transcription by RNA polymerase II (Pol II) is utilized extensively to generate the pattern of mRNAs needed to specify cell types and to respond to environmental changes. After Pol II initiates, negative elongation factors cause it to pause in a promoter proximal position. These polymerases are poised to respond to the positive transcription elongation factor P-TEFb, and then enter productive elongation only under the appropriate set of signals to generate full-length properly processed mRNAs. Recent global analyses of Pol II and elongation factors, mechanisms that regulate P-TEFb involving the 7SK small nuclear ribonucleoprotein (snRNP), factors that control both the negative and positive elongation properties of Pol II, and the mRNA processing events that are coupled with elongation are discussed.
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Affiliation(s)
- Qiang Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.
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Toossi Z, Wu M, Hirsch CS, Mayanja-Kizza H, Baseke J, Aung H, Canaday DH, Fujinaga K. Activation of P-TEFb at sites of dual HIV/TB infection, and inhibition of MTB-induced HIV transcriptional activation by the inhibitor of CDK9, Indirubin-3'-monoxime. AIDS Res Hum Retroviruses 2012; 28:182-7. [PMID: 21453127 DOI: 10.1089/aid.2010.0211] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
At sites of Mycobacterium tuberculosis (MTB) infection, HIV-1 replication is increased during tuberculosis (TB). Here we investigated the role of positive transcription elongation factor (P-TEFb), comprised of CycT1 and CDK9, as the cellular cofactor of HIV-1 Tat protein in transcriptional activation of HIV-1 in mononuclear cells from HIV-1-infected patients with pleural TB. Expression of CycT1 in response to MTB was assessed in mononuclear cells from pleural fluid (PFMC) and blood (PBMC) from HIV/TB patients with pleural TB, and in blood monocytes (MN) from singly infected HIV-1-seropositive subjects. We then examined whether the CDK9 inhibitor, Indirubin 3'-monoxime (IM), was effective in inhibition of MTB-induced HIV-1 mRNA expression. We found higher expression of CycT1 mRNA in PFMCs as compared to PBMCs from HIV/TB-coinfected subjects. MTB induced the expression of CycT1 and HIV-1 gag/pol mRNA in both PFMCs from HIV/TB subjects and MN from HIV-1-infected subjects. CycT1 protein was also induced by MTB stimulation in PFMCs from HIV/TB patients, and both MN and in vitro-derived macrophages. Inhibition of CDK9 by IM in both PFMCs from HIV/TB and MN from HIV-1-infected subjects in response to MTB led to inhibition of HIV-1 mRNA expression. These data imply that IM may be useful as an adjunctive therapy in control of HIV-1 replication in HIV/TB dually infected subjects.
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Affiliation(s)
- Zahra Toossi
- Case Western Reserve University, Cleveland, Ohio
- Veterans Affairs Medical Center, Cleveland, Ohio
| | - Mianda Wu
- Case Western Reserve University, Cleveland, Ohio
| | | | - Harriet Mayanja-Kizza
- Makerere University and National Tuberculosis and Leprosy Program, Kampala, Uganda
- Joint Clinical Research Center, Kampala, Uganda
| | - Joy Baseke
- Joint Clinical Research Center, Kampala, Uganda
| | - Htin Aung
- Case Western Reserve University, Cleveland, Ohio
| | | | - Koh Fujinaga
- Case Western Reserve University, Cleveland, Ohio
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Regulation of cyclin T1 and HIV-1 Replication by microRNAs in resting CD4+ T lymphocytes. J Virol 2011; 86:3244-52. [PMID: 22205749 DOI: 10.1128/jvi.05065-11] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The replication of integrated human immunodeficiency virus type 1 (HIV-1) is dependent on the cellular cofactor cyclin T1, which binds the viral Tat protein and activates the RNA polymerase II transcription of the integrated provirus. The activation of resting CD4(+) T cells upregulates cyclin T1 protein levels independently of an increase in cyclin T1 mRNA levels, suggesting a translational repression of cyclin T1 in resting CD4(+) T cells. Hypothesizing that microRNAs (miRNAs) repress cyclin T1 translation in resting CD4(+) T cells and that this inhibition is lifted upon cell activation, we used microarray expression analysis to identify miRNAs miR-27b, miR-29b, miR-150, and miR-223 as being significantly downregulated upon CD4(+) T cell activation. The overexpression of these miRNAs decreased endogenous cyclin T1 protein levels, while treatment with the corresponding antagomiRs increased cyclin T1 protein levels. An miR-27b binding site within the cyclin T1 3' untranslated region (3'UTR) was identified and confirmed to be functional after the mutation of key resides abrogated the ability of miR-27b to decrease the expression of a luciferase reporter upstream of the cyclin T1 3'UTR. Ago2 immunoprecipitation revealed an association with cyclin T1 mRNA that was decreased following treatment with miR-27b and miR-29b antagomiRs. Cells overexpressing miR-27b showed decreased viral gene expression levels of the HIV-1 reporter virus and a decreased replication of strain NL4.3; a partial rescue of viral transcription could be seen following the transfection of cyclin T1. These results implicate miR-27b as a novel regulator of cyclin T1 protein levels and HIV-1 replication, while miR-29b, miR-223, and miR-150 may regulate cyclin T1 indirectly.
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Nilson KA, Price DH. The Role of RNA Polymerase II Elongation Control in HIV-1 Gene Expression, Replication, and Latency. GENETICS RESEARCH INTERNATIONAL 2011; 2011:726901. [PMID: 22567366 PMCID: PMC3335632 DOI: 10.4061/2011/726901] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 07/22/2011] [Indexed: 11/20/2022]
Abstract
HIV-1 usurps the RNA polymerase II elongation control machinery to regulate the expression of its genome during lytic and latent viral stages. After integration into the host genome, the HIV promoter within the long terminal repeat (LTR) is subject to potent downregulation in a postinitiation step of transcription. Once produced, the viral protein Tat commandeers the positive transcription elongation factor, P-TEFb, and brings it to the engaged RNA polymerase II (Pol II), leading to the production of viral proteins and genomic RNA. HIV can also enter a latent phase during which factors that regulate Pol II elongation may play a role in keeping the virus silent. HIV, the causative agent of AIDS, is a worldwide health concern. It is hoped that knowledge of the mechanisms regulating the expression of the HIV genome will lead to treatments and ultimately a cure.
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Affiliation(s)
- Kyle A Nilson
- Molecular and Cellular Biology Program, The University of Iowa, Iowa City, IA 52242, USA
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Hoque M, Shamanna RA, Guan D, Pe'ery T, Mathews MB. HIV-1 replication and latency are regulated by translational control of cyclin T1. J Mol Biol 2011; 410:917-32. [PMID: 21763496 DOI: 10.1016/j.jmb.2011.03.060] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 03/24/2011] [Accepted: 03/25/2011] [Indexed: 11/29/2022]
Abstract
Human immunodeficiency virus (HIV) exploits cellular proteins during its replicative cycle and latent infection. The positive transcription elongation factor b (P-TEFb) is a key cellular transcription factor critical for these viral processes and is a drug target. During viral replication, P-TEFb is recruited via interactions of its cyclin T1 subunit with the HIV Tat (transactivator of transcription) protein and TAR (transactivation response) element. Through RNA silencing and over-expression experiments, we discovered that nuclear factor 90 (NF90), a cellular RNA binding protein, regulates P-TEFb expression. NF90 depletion reduced cyclin T1 protein levels by inhibiting translation initiation. Regulation was mediated by the 3' untranslated region of cyclin T1 mRNA independently of microRNAs. Cyclin T1 induction is involved in the escape of HIV-1 from latency. We show that the activation of viral replication by phorbol ester in latently infected monocytic cells requires the posttranscriptional induction of NF90 and cyclin T1, implicating NF90 in protein kinase C signaling pathways. This investigation reveals a novel mechanism of cyclin T1 regulation and establishes NF90 as a regulator of HIV-1 replication during both productive infection and induction from latency.
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Affiliation(s)
- Mainul Hoque
- Department of Biochemistry and Molecular Biology, UMDNJ-New Jersey Medical School, PO Box 1709, Newark, NJ 07101-1709, USA
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40
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Khan SZ, Mitra D. Cyclin K inhibits HIV-1 gene expression and replication by interfering with cyclin-dependent kinase 9 (CDK9)-cyclin T1 interaction in Nef-dependent manner. J Biol Chem 2011; 286:22943-54. [PMID: 21555514 DOI: 10.1074/jbc.m110.201194] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human immunodeficiency virus-1 (HIV-1) exploits a number of host cellular factors for successful survival and propagation. The viral protein Nef plays an important role in HIV-1 pathogenesis by interacting with various cellular proteins. In the present work, we identified Cyclin K (CycK) as a novel Nef-interacting protein, and for the first time, we showed that CycK inhibits HIV-1 gene expression and replication in a Nef-dependent manner. The positive elongation factor b complex comprising cyclin-dependent kinase 9 (CDK9) and Cyclin T1 is a critical cellular complex required for viral gene expression and replication. Enhanced expression of CycK in the presence of Nef induced CycK-CDK9 binding, which prevented CDK9-Cyclin T1 complex formation and nuclear translocation of CDK9, resulting in inhibition of HIV-1 long terminal repeat-driven gene expression. Furthermore, this effect of CycK was not observed with Nef-deleted virus, indicating the importance of Nef in this phenomenon. Finally, silencing of CycK in HIV-1-infected cells resulted in increased translocation of CDK9 into the nucleus, leading to increased viral gene expression and replication. These data also suggest that endogenous CycK might act as an inhibitory factor for HIV-1 gene expression and replication in T-cells. Thus, our results clearly demonstrate that CycK utilizes HIV-1 Nef protein to displace CycT1 from the positive elongation factor b complex, resulting in inhibition of HIV-1 gene expression and replication.
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Choudhary SK, Margolis DM. Curing HIV: Pharmacologic approaches to target HIV-1 latency. Annu Rev Pharmacol Toxicol 2011; 51:397-418. [PMID: 21210747 DOI: 10.1146/annurev-pharmtox-010510-100237] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
HIV-1 infection persists even after years of antiretroviral therapy (ART). Although ART can halt viral replication and thereby reduce viremia to clinically undetectable levels, proviral latency established within the host genome remains largely unaffected by ART and can replenish systemic infection following interruption of therapy. Pharmacologic strategies, which not only target viral replication but also deplete proviral infection, are required for successful clearance of HIV-1 infection. This review highlights the current understanding of molecular mechanisms that establish and maintain HIV-1 latency in its major reservoir, the resting memory CD4(+) T cell. We also identify the molecular targets that might be exploited to induce HIV-1 expression, remove epigenetic restrictions, or enhance effective transcription. Finally, we discuss the potential pharmacologic approaches toward targeting viral persistence in different cellular and anatomical reservoirs to achieve a cure of HIV-1 infection.
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Affiliation(s)
- Shailesh K Choudhary
- Departments of Medicine, University of North Carolina at Chapel Hill, 27599, USA
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Freter R, Osawa M, Nishikawa SI. Adult stem cells exhibit global suppression of RNA polymerase II serine-2 phosphorylation. Stem Cells 2010; 28:1571-80. [PMID: 20641035 DOI: 10.1002/stem.476] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Adult stem cells, which are characterized by their capacity for self-renewal and differentiation, participate in tissue homeostasis and response to injury. They are thought to enter a state of relative quiescence, known as reversible cell cycle arrest, but the underlying molecular mechanisms remain poorly characterized. Previous data from our laboratory has shown that housekeeping gene expression is downregulated in melanocyte stem cells (MelSCs), suggesting a global suppression of mRNA transcription. We now show, using antibodies against specific phosphorylated forms of RNA polymerase II (RNApII), that adult MelSCs do not undergo productive mRNA transcription elongation, while RNApII is activated and initialized, ready to synthesize mRNA upon stimulation, and that the RNApII kinase CDK9 is absent in adult MelSCs. Interestingly, other adult stem cells also, including keratinocyte, muscle, spermatogonia, and hematopoietic stem cells, showed a similar absence of RNApII phosphorylation. Although it is difficult to show the functional significance of this observation in vivo, CDK9 inhibition resulted in enhanced survival of cells that are deprived from survival factors. We conclude that the absence of productive mRNA transcription is an early, specific, and conserved characteristic of adult stem cells. Downregulation of mRNA transcription may lead to decreased rates of metabolism, and protection from cellular and genetic damage. Screening heterogeneous tissues, including tumors, for transcriptionally quiescent cells may result in the identification of cells with stem cell-like phenotypes.
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Affiliation(s)
- Rasmus Freter
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, United Kingdom.
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Du T, Li B, Li H, Li M, Hertz L, Peng L. Signaling pathways of isoproterenol-induced ERK1/2 phosphorylation in primary cultures of astrocytes are concentration-dependent. J Neurochem 2010; 115:1007-23. [PMID: 20831657 DOI: 10.1111/j.1471-4159.2010.06995.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Stimulation of β-adrenoceptors activates the canonical adenylate cyclase pathway (via G(s) protein) but can also evoke phosphorylation of extracellular-regulated kinases 1 and 2 (ERK(1/2) ) via G(s)/G(i) switching or β-arrestin-mediated recruitment of Src. In primary cultures of mouse astrocytes, activation of the former of these pathways required micromolar concentrations of the β(1)/β(2) -adrenergic agonist isoproterenol, that acted on β(1)-adrenoceptors, whereas the latter was activated already by nanomolar concentrations, acting on β(2) receptors. Protein kinase A activity was required for G(s)/G(i) switching, which was followed by Ca(2+) release from intracellular stores and G(iα)- and metalloproteinase-dependent transactivation of the epidermal growth factor receptor (EGFR; at its Y1173 phophorylation site), via its receptor-tyrosine kinase, β-arrestin 1/2 recruitment, and MAPK/ERK kinase-dependent ERK(1/2) phosphorylation. ERK(1/2) phosphorylation by Src activation depended on β-arrestin 2, but not β-arrestin 1, was accompanied by Src/EGFR co-precipitation and phosphorylation of the EGFR at the Src-phosphorylated Y845 site and the Y1045 autophosphorylation site; it was independent of transactivation but dependent on MAPK/ERK kinase activity, suggesting EGFR phosphorylation independently of the receptor-tyrosine kinase or activation of Ras or Raf directly from Src. Most astrocytic consequences of activating either pathway (or both) are unknown, but morphological differentiation and increase in glial fibrillary acidic protein in response to dibutyryl cAMP-mediated increase in cAMP depend on G(s)/G(i) switching and transactivation.
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Affiliation(s)
- Ting Du
- Department of Clinical Pharmacology, China Medical University, Shenyang, China
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44
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Dow EC, Liu H, Rice AP. T-loop phosphorylated Cdk9 localizes to nuclear speckle domains which may serve as sites of active P-TEFb function and exchange between the Brd4 and 7SK/HEXIM1 regulatory complexes. J Cell Physiol 2010; 224:84-93. [PMID: 20201073 DOI: 10.1002/jcp.22096] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
P-TEFb functions to induce the elongation step of RNA polymerase II transcription by phosphorylating the carboxyl-terminal domain of the largest subunit of RNA polymerase II. Core P-TEFb is comprised of Cdk9 and a cyclin regulatory subunit, with Cyclin T1 being the predominant Cdk9-associated cyclin. The kinase activity of P-TEFb is dependent on phosphorylation of the Thr186 residue located within the T-loop domain of the Cdk9 subunit. Here, we used immunofluorescence deconvolution microscopy to examine the subcellular distribution of phospho-Thr186 Cdk9/Cyclin T1 P-TEFb heterodimers. We found that phospho-Thr186 Cdk9 displays a punctate distribution throughout the non-nucleolar nucleoplasm and it co-localizes with Cyclin T1 almost exclusively within nuclear speckle domains. Phospho-Thr186 Cdk9 predominantly co-localized with the hyperphosphorylated forms of RNA polymerase II. Transient expression of kinase-defective Cdk9 mutants revealed that neither is Thr186 phosphorylation or kinase activity required for Cdk9 speckle localization. Lastly, both the Brd4 and HEXIM1 proteins interact with P-TEFb at or very near speckle domains and treatment of cells with the Cdk9 inhibitor flavopiridol alters this distribution. These results indicate that the active form of P-TEFb resides in nuclear speckles and raises the possibility that speckles are sites of P-TEFb function and exchange between negative and positive P-TEFb regulatory complexes.
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Affiliation(s)
- Eugene C Dow
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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Garriga J, Xie H, Obradovic Z, Graña X. Selective control of gene expression by CDK9 in human cells. J Cell Physiol 2009; 222:200-8. [PMID: 19780058 DOI: 10.1002/jcp.21938] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
CDK9 associates with T-type cyclins and positively regulates transcriptional elongation by phosphorylating RNA polymerase II (RNAPII) and negative elongation factors. However, it is unclear whether CDK9 is required for transcription of most genes by RNAPII or alternatively plays a role regulating the expression of restricted subsets of genes. We have investigated the direct effects of inhibiting cellular CDK9 activity in global gene expression in human cells by using a dominant-negative form of CDK9 (dnCDK9). We have also compared direct inhibition of cellular CDK9 activity to pharmacological inhibition with flavopiridol (FVP), a CDK inhibitor that potently inhibits CDK9 and cellular transcription. Because of its presumed selectivity for CDK9, FVP has been previously used as a tool to infer the role of CDK9 on global gene expression. DNA microarray analyses described here show that inhibition of gene expression by FVP is consistent with global inhibition of transcription. However, specific inhibition of CDK9 activity with dnCDK9 leads to a distinctive pattern of changes in gene expression, with more genes being specifically upregulated (122) than downregulated (84). Indeed, the expression of many short-lived transcripts downregulated by FVP is not modulated by dnCDK9. Nevertheless, consistently with FVP inhibiting CDK9 activity, a significant number of the genes downregulated/upregulated by dnCDK9 are modulated with a similar trend by FVP. Our data suggests that the potent effects of FVP on transcription are likely to involve inhibition of CTD kinases in addition to CDK9. Our data also suggest complex and gene-specific modulation of gene expression by CDK9.
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Affiliation(s)
- Judit Garriga
- Fels Institute for Cancer Research and Molecular Biology, Philadelphia, Pennsylvania 19140, USA
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46
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Functional Evolution of Cyclin-Dependent Kinases. Mol Biotechnol 2009; 42:14-29. [DOI: 10.1007/s12033-008-9126-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Accepted: 11/01/2008] [Indexed: 10/21/2022]
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47
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Epigenetic silencing of human immunodeficiency virus (HIV) transcription by formation of restrictive chromatin structures at the viral long terminal repeat drives the progressive entry of HIV into latency. J Virol 2008; 82:12291-303. [PMID: 18829756 DOI: 10.1128/jvi.01383-08] [Citation(s) in RCA: 244] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The molecular mechanisms utilized by human immunodeficiency virus (HIV) to enter latency are poorly understood. Following the infection of Jurkat T cells with lentiviral vectors that express Tat in cis, gene expression is progressively silenced. Silencing is greatly enhanced when the lentiviral vectors carry an attenuated Tat gene with the H13L mutation. Individual clones of lentivirus-infected cells showed a wide range of shutdown rates, with the majority showing a 50% silencing frequency between 30 to 80 days. The silenced clones characteristically contained a small fraction (0 to 15%) of activated cells that continued to express d2EGFP. When d2EGFP(+) and d2EGFP(-) cell populations were isolated from the shutdown clones, they quickly reverted to the original distribution of inactive and active cells, suggesting that the d2EGFP(+) cells arise from stochastic fluctuations in gene expression. The detailed analysis of transcription initiation and elongation using chromatin immunoprecipitation (ChIP) assays confirms that Tat levels are restricted in the latently infected cells but gradually rise during proviral reactivation. ChIP assays using clones of latently infected cells demonstrate that the latent proviruses carry high levels of deacetylated histones and trimethylated histones. In contrast, the cellular genes IkappaB alpha and GAPDH had high levels of acetylated histones and no trimethylated histones. The levels of trimethylated histone H3 and HP1-alpha associated with HIV proviruses fell rapidly after tumor necrosis factor alpha activation. The progressive shutdown of HIV transcription following infection suggests that epigenetic mechanisms targeting chromatin structures selectively restrict HIV transcription initiation. This decreases Tat production below the levels that are required to sustain HIV gene expression.
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48
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Choudhary SK, Archin NM, Margolis DM. Hexamethylbisacetamide and disruption of human immunodeficiency virus type 1 latency in CD4(+) T cells. J Infect Dis 2008; 197:1162-70. [PMID: 18419522 DOI: 10.1086/529525] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Novel therapeutic approaches are needed to attack persistent proviral human immunodeficiency type 1 (HIV-1) infection. Hexamethylbisacetamide (HMBA), a hybrid bipolar compound, induces expression of the HIV-1 promoter in the long terminal repeat (LTR) region in a Tat-independent manner but mimics the effect of Tat, overcoming barriers to LTR expression and increasing the processivity of LTR transcription complexes. METHODS We studied alterations in cellular factors and their LTR occupancy induced by HMBA in models of latent HIV-1 infection. We measured the induction of viral outgrowth by HMBA in resting CD4(+) T cells from aviremic HIV-1-infected donors. RESULTS HMBA induced outgrowth of HIV-1 from resting CD4(+) T cells recovered from aviremic patients treated with antiretroviral therapy (ART). HMBA triggered cyclin-dependent kinase 9 (CDK9) recruitment to the LTR, a key factor in the induction of efficient HIV-1 expression, via an unexpected interaction with the transcription factor Sp1. The availability of Sp1 and Sp1 DNA binding sites were necessary for HMBA-induced CDK9 recruitment and LTR expression. HMBA signaling via both protein kinase C mu and phosphatidylinositol 3-kinase appeared to contribute to LTR induction. CONCLUSIONS The novel mechanism through which HMBA disrupts latent HIV-1 infection involves 2 cellular kinases that may be therapeutically exploited to induce expression of persistent proviral HIV-1.
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Affiliation(s)
- Shailesh K Choudhary
- Departments of Medicine, University of North Carolina at Chapel Hill 27599-7435, USA
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49
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De Falco G, Leucci E, Onnis A, Bellan C, Tigli C, Wirths S, Cerino G, Cocco M, Crupi D, De Luca A, Lanzavecchia A, Tosi P, Leoncini L, Giordano A. Cdk9/Cyclin T1 complex: A key player during the activation/differentiation process of normal lymphoid B cells. J Cell Physiol 2008; 215:276-82. [DOI: 10.1002/jcp.21311] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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50
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Acetylation of conserved lysines in the catalytic core of cyclin-dependent kinase 9 inhibits kinase activity and regulates transcription. Mol Cell Biol 2008; 28:2201-12. [PMID: 18250157 DOI: 10.1128/mcb.01557-07] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Promoter clearance and transcriptional processivity in eukaryotic cells are fundamentally regulated by the phosphorylation of the carboxy-terminal domain of RNA polymerase II (RNAPII). One of the kinases that essentially performs this function is P-TEFb (positive transcription elongation factor b), which is composed of cyclin-dependent kinase 9 (CDK9) associated with members of the cyclin T family. Here we show that cellular GCN5 and P/CAF, members of the GCN5-related N-acetyltransferase family of histone acetyltransferases, regulate CDK9 function by specifically acetylating the catalytic core of the enzyme and, in particular, a lysine that is essential for ATP coordination and the phosphotransfer reaction. Acetylation markedly reduces both the kinase function and transcriptional activity of P-TEFb. In contrast to unmodified CDK9, the acetylated fraction of the enzyme is specifically found in the insoluble nuclear matrix compartment. Acetylated CDK9 associates with the transcriptionally silent human immunodeficiency virus type 1 provirus; upon transcriptional activation, it is replaced by the unmodified form, which is involved in the elongating phase of transcription marked by Ser2-phosphorylated RNAPII. Given the conservation of the CDK9 acetylated residues in the catalytic task of virtually all CDK proteins, we anticipate that this mechanism of regulation might play a broader role in controlling the function of other members of this kinase family.
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