1
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CDK9 keeps RNA polymerase II on track. Cell Mol Life Sci 2021; 78:5543-5567. [PMID: 34146121 PMCID: PMC8257543 DOI: 10.1007/s00018-021-03878-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/26/2021] [Accepted: 06/08/2021] [Indexed: 12/30/2022]
Abstract
Cyclin-dependent kinase 9 (CDK9), the kinase component of positive transcription elongation factor b (P-TEFb), is essential for transcription of most protein-coding genes by RNA polymerase II (RNAPII). By releasing promoter-proximally paused RNAPII into gene bodies, CDK9 controls the entry of RNAPII into productive elongation and is, therefore, critical for efficient synthesis of full-length messenger (m)RNAs. In recent years, new players involved in P-TEFb-dependent processes have been identified and an important function of CDK9 in coordinating elongation with transcription initiation and termination has been unveiled. As the regulatory functions of CDK9 in gene expression continue to expand, a number of human pathologies, including cancers, have been associated with aberrant CDK9 activity, underscoring the need to properly regulate CDK9. Here, I provide an overview of CDK9 function and regulation, with an emphasis on CDK9 dysregulation in human diseases.
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2
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Moranguinho I, Valente ST. Block-And-Lock: New Horizons for a Cure for HIV-1. Viruses 2020; 12:v12121443. [PMID: 33334019 PMCID: PMC7765451 DOI: 10.3390/v12121443] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/01/2020] [Accepted: 12/08/2020] [Indexed: 12/12/2022] Open
Abstract
HIV-1/AIDS remains a global public health problem. The world health organization (WHO) reported at the end of 2019 that 38 million people were living with HIV-1 worldwide, of which only 67% were accessing antiretroviral therapy (ART). Despite great success in the clinical management of HIV-1 infection, ART does not eliminate the virus from the host genome. Instead, HIV-1 remains latent as a viral reservoir in any tissue containing resting memory CD4+ T cells. The elimination of these residual proviruses that can reseed full-blown infection upon treatment interruption remains the major barrier towards curing HIV-1. Novel approaches have recently been developed to excise or disrupt the virus from the host cells (e.g., gene editing with the CRISPR-Cas system) to permanently shut off transcription of the virus (block-and-lock and RNA interference strategies), or to reactivate the virus from cell reservoirs so that it can be eliminated by the immune system or cytopathic effects (shock-and-kill strategy). Here, we will review each of these approaches, with the major focus placed on the block-and-lock strategy.
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3
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Tamalet C, Devaux C, Dubourg G, Colson P. Resistance to human immunodeficiency virus infection: a rare but neglected state. Ann N Y Acad Sci 2020; 1485:22-42. [PMID: 33009659 DOI: 10.1111/nyas.14452] [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: 04/15/2020] [Revised: 06/25/2020] [Accepted: 07/07/2020] [Indexed: 11/29/2022]
Abstract
The natural history of human immunodeficiency virus (HIV) infection is well understood. In most individuals sexually exposed to HIV, the risk of becoming infected depends on the viral load and on sexual practices and gender. However, a low percentage of individuals who practice frequent unprotected sexual intercourse with HIV-infected partners remain uninfected. Although the systematic study of these individuals has made it possible to identify HIV resistance factors including protective genetic patterns, such epidemiological situations remain paradoxical and not fully understood. In vitro experiments have demonstrated that peripheral blood mononuclear cells (PBMCs) from HIV-free, unexposed blood donors are not equally susceptible to HIV infection; in addition, PBMCs from highly exposed seronegative individuals are generally resistant to infection by primary HIV clinical isolates. We review the literature on permissiveness of PBMCs from healthy blood donors and uninfected hyperexposed individuals to sustained infection and replication of HIV-1 in vitro. In addition, we focus on recent evidence indicating that the gut microbiota may either contribute to natural resistance to or delay replication of HIV infected individuals.
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Affiliation(s)
- Catherine Tamalet
- IHU Méditerranée Infection and Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique-Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
| | - Christian Devaux
- IHU Méditerranée Infection and Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique-Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
| | - Gregory Dubourg
- IHU Méditerranée Infection and Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique-Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
| | - Philippe Colson
- IHU Méditerranée Infection and Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique-Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
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4
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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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5
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DeMarino C, Cowen M, Pleet ML, Pinto DO, Khatkar P, Erickson J, Docken SS, Russell N, Reichmuth B, Phan T, Kuang Y, Anderson DM, Emelianenko M, Kashanchi F. Differences in Transcriptional Dynamics Between T-cells and Macrophages as Determined by a Three-State Mathematical Model. Sci Rep 2020; 10:2227. [PMID: 32042107 PMCID: PMC7010665 DOI: 10.1038/s41598-020-59008-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 01/17/2020] [Indexed: 12/18/2022] Open
Abstract
HIV-1 viral transcription persists in patients despite antiretroviral treatment, potentially due to intermittent HIV-1 LTR activation. While several mathematical models have been explored in the context of LTR-protein interactions, in this work for the first time HIV-1 LTR model featuring repressed, intermediate, and activated LTR states is integrated with generation of long (env) and short (TAR) RNAs and proteins (Tat, Pr55, and p24) in T-cells and macrophages using both cell lines and infected primary cells. This type of extended modeling framework allows us to compare and contrast behavior of these two cell types. We demonstrate that they exhibit unique LTR dynamics, which ultimately results in differences in the magnitude of viral products generated. One of the distinctive features of this work is that it relies on experimental data in reaction rate computations. Two RNA transcription rates from the activated promoter states are fit by comparison of experimental data to model predictions. Fitting to the data also provides estimates for the degradation/exit rates for long and short viral RNA. Our experimentally generated data is in reasonable agreement for the T-cell as well macrophage population and gives strong evidence in support of using the proposed integrated modeling paradigm. Sensitivity analysis performed using Latin hypercube sampling method confirms robustness of the model with respect to small parameter perturbations. Finally, incorporation of a transcription inhibitor (F07#13) into the governing equations demonstrates how the model can be used to assess drug efficacy. Collectively, our model indicates transcriptional differences between latently HIV-1 infected T-cells and macrophages and provides a novel platform to study various transcriptional dynamics leading to latency or activation in numerous cell types and physiological conditions.
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MESH Headings
- Anti-HIV Agents/pharmacology
- Anti-HIV Agents/therapeutic use
- Cell Line
- Drug Resistance, Viral/drug effects
- Drug Resistance, Viral/genetics
- Drug Resistance, Viral/immunology
- Gene Expression Regulation, Viral/immunology
- HIV Infections/blood
- HIV Infections/drug therapy
- HIV Infections/immunology
- HIV Long Terminal Repeat/genetics
- HIV-1/drug effects
- HIV-1/genetics
- HIV-1/immunology
- Humans
- Macrophages/immunology
- Macrophages/virology
- Models, Genetic
- Models, Immunological
- Primary Cell Culture
- RNA, Viral/genetics
- RNA, Viral/metabolism
- T-Lymphocytes/immunology
- T-Lymphocytes/virology
- Transcription, Genetic/drug effects
- Transcription, Genetic/immunology
- Virus Replication/drug effects
- Virus Replication/genetics
- Virus Replication/immunology
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Affiliation(s)
- Catherine DeMarino
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA, USA
| | - Maria Cowen
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA, USA
| | - Michelle L Pleet
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA, USA
| | - Daniel O Pinto
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA, USA
| | - Pooja Khatkar
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA, USA
| | - James Erickson
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA, USA
| | - Steffen S Docken
- Department of Mathematics, University of California Davis, Davis, CA, USA
| | - Nicholas Russell
- Department of Mathematical Sciences, University of Delaware, Newark, DE, USA
| | - Blake Reichmuth
- Department of Mathematical Sciences, George Mason University, Fairfax, VA, USA
| | - Tin Phan
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, USA
| | - Yang Kuang
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, USA
| | - Daniel M Anderson
- Department of Mathematical Sciences, George Mason University, Fairfax, VA, USA.
| | - Maria Emelianenko
- Department of Mathematical Sciences, George Mason University, Fairfax, VA, USA.
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA, USA.
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6
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Mukherjee K, English N, Meers C, Kim H, Jonke A, Storici F, Torres M. Systematic analysis of linker histone PTM hotspots reveals phosphorylation sites that modulate homologous recombination and DSB repair. DNA Repair (Amst) 2019; 86:102763. [PMID: 31821952 DOI: 10.1016/j.dnarep.2019.102763] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 11/26/2019] [Accepted: 11/28/2019] [Indexed: 02/07/2023]
Abstract
Double strand-breaks (DSBs) of genomic DNA caused by ionizing radiation or mutagenic chemicals are a common source of mutation, recombination, chromosomal aberration, and cell death. Linker histones are DNA packaging proteins with established roles in chromatin compaction, gene transcription, and in homologous recombination (HR)-mediated DNA repair. Using a machine-learning model for functional prioritization of eukaryotic post-translational modifications (PTMs) in combination with genetic and biochemical experiments with the yeast linker histone, Hho1, we discovered that site-specific phosphorylation sites regulate HR and HR-mediated DSB repair. Five total sites were investigated (T10, S65, S141, S173, and S174), ranging from high to low function potential as determined by the model. Of these, we confirmed S173/174 are phosphorylated in yeast by mass spectrometry and found no evidence of phosphorylation at the other sites. Phospho-nullifying mutations at these two sites results in a significant decrease in HR-mediated DSB repair templated either with oligonucleotides or a homologous chromosome, while phospho-mimicing mutations have no effect. S65, corresponding to a mammalian phosphosite that is conserved in yeast, exhibited similar effects. None of the mutations affected base- or nucleotide-excision repair, nor did they disrupt non-homologous end joining or RNA-mediated repair of DSBs when sequence heterology between the break and repair template strands was low. More extensive analysis of the S174 phospho-null mutant revealed that its repression of HR and DSB repair is proportional to the degree of sequence heterology between DSB ends and the HR repair template. Taken together, these data demonstrate the utility of machine learning for the discovery of functional PTM hotspots, reveal linker histone phosphorylation sites necessary for HR and HR-mediated DSB repair, and provide insight into the context-dependent control of DNA integrity by the yeast linker histone Hho1.
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Affiliation(s)
- Kuntal Mukherjee
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive NW Atlanta GA 30332,USA
| | - Nolan English
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive NW Atlanta GA 30332,USA
| | - Chance Meers
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive NW Atlanta GA 30332,USA
| | - Hyojung Kim
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive NW Atlanta GA 30332,USA; School of Chemistry and Biochemistry, Georgia Institute of Technology, 950 Atlantic Drive NW Atlanta GA 30332,USA
| | - Alex Jonke
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive NW Atlanta GA 30332,USA
| | - Francesca Storici
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive NW Atlanta GA 30332,USA
| | - Matthew Torres
- School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Drive NW Atlanta GA 30332,USA.
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7
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Chen L, Keppler OT, Schölz C. Post-translational Modification-Based Regulation of HIV Replication. Front Microbiol 2018; 9:2131. [PMID: 30254620 PMCID: PMC6141784 DOI: 10.3389/fmicb.2018.02131] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/20/2018] [Indexed: 12/13/2022] Open
Abstract
Human immunodeficiency virus (HIV) relies heavily on the host cellular machinery for production of viral progeny. To exploit cellular proteins for replication and to overcome host factors with antiviral activity, HIV has evolved a set of regulatory and accessory proteins to shape an optimized environment for its replication and to facilitate evasion from the immune system. Several cellular pathways are hijacked by the virus to modulate critical steps during the viral life cycle. Thereby, post-translational modifications (PTMs) of viral and cellular proteins gain increasingly attention as modifying enzymes regulate virtually every step of the viral replication cycle. This review summarizes the current knowledge of HIV-host interactions influenced by PTMs with a special focus on acetylation, ubiquitination, and phosphorylation of proteins linked to cellular signaling and viral replication. Insights into these interactions are surmised to aid development of new intervention strategies.
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Affiliation(s)
- Lin Chen
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Oliver T Keppler
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Christian Schölz
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
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8
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Paparidis NFDS, Durvale MC, Canduri F. The emerging picture of CDK9/P-TEFb: more than 20 years of advances since PITALRE. MOLECULAR BIOSYSTEMS 2017; 13:246-276. [PMID: 27833949 DOI: 10.1039/c6mb00387g] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
CDK9 is a prominent member of the transcriptional CDKs subfamily, a group of kinases whose function is to control the primary steps of mRNA synthesis and processing by eukaryotic RNA polymerase II. As a cyclin-dependent kinase, CDK9 activation in vivo depends upon its association with T-type cyclins to assemble the positive transcription elongation factor (P-TEFb). Although CDK9/P-TEFb phosphorylates the C-terminal domain of RNAP II in the same positions targeted by CDK7 (TFIIH) and CDK8 (Mediator), the former does not participate in the transcription initiation, but rather plays a unique role by driving the polymerase to productive elongation. In addition to RNAP II CTD, the negative transcription elongation factors DSIF and NELF also represent major CDK9 substrates, whose phosphorylation is required to overcome the proximal pause of the polymerase. CDK9 is recruited to specific genes through proteins that interact with both P-TEFb and distinct elements in DNA, RNA or chromatin, where it modulates the activity of individual RNAP II transcription complexes. The regulation of CDK9 function is an intricate network that includes post-translational modifications (phosphorylation/dephosphorylation and acetylation/deacetylation of key residues) as well as the association of P-TEFb with various proteins that can stimulate or inhibit its kinase activity. Several cases of CDK9 deregulation have been linked to important human diseases, including various types of cancer and also AIDS (due to its essential role in HIV replication). Not only HIV, but also many other human viruses have been shown to depend strongly on CDK9 activity to be transcribed within host cells. This review summarizes the main advances made on CDK9/P-TEFb field in more than 20 years, introducing the structural, functional and genetic aspects that have been elucidated ever since.
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Affiliation(s)
- Nikolas Ferreira Dos Santos Paparidis
- Department of Chemistry and Molecular Physics, Institute of Chemistry of Sao Carlos, Sao Paulo University, Av. Trabalhador Sãocarlense, 400, Zip Code 780, 13560-970, São Carlos-SP, Brazil.
| | - Maxwell Castro Durvale
- Department of Biochemistry, Institute of Chemistry, Sao Paulo University, Av. Prof. Lineu Prestes, 748, 05508-000, Butantã - São Paulo - SP, Brazil
| | - Fernanda Canduri
- Department of Chemistry and Molecular Physics, Institute of Chemistry of Sao Carlos, Sao Paulo University, Av. Trabalhador Sãocarlense, 400, Zip Code 780, 13560-970, São Carlos-SP, Brazil.
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9
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Turner AMW, Margolis DM. Chromatin Regulation and the Histone Code in HIV Latency
. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2017; 90:229-243. [PMID: 28656010 PMCID: PMC5482300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The formation of a latent reservoir of Human Immunodeficiency Virus (HIV) infection hidden from immune clearance remains a significant obstacle to approaches to eradicate HIV infection. Towards an understanding of the mechanisms of HIV persistence, there is a growing body of work implicating epigenetic regulation of chromatin in establishment and maintenance of this latent reservoir. Here we discuss recent advances in the field of chromatin regulation, specifically in our understanding of the histone code, and how these discoveries relate to our current knowledge of the chromatin mechanisms linked to HIV transcriptional repression and the reversal of latency. We also examine mechanisms unexplored in the context of HIV latency and briefly discuss current therapies aimed at the induction of proviral expression within latently infected cells. We aim to emphasize that a greater understanding of the epigenetic mechanisms which govern HIV latency could lead to new therapeutic targets for latency reversal and clearance cure strategies.
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Affiliation(s)
- Anne-Marie W. Turner
- UNC HIV Cure Center, University of North Carolina at Chapel Hill, Chapel Hill, NC,Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - David M. Margolis
- UNC HIV Cure Center, University of North Carolina at Chapel Hill, Chapel Hill, NC,Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC,Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC,Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC,To whom all correspondence should be addressed: David Margolis, University of North Carolina at Chapel Hill, 2016 Genetic Medicine Building, CB#7042, 120 Mason Farm Road, Chapel Hill, NC, 27599-7435, Tel: (919) 966-6388, .
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10
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Liao R, Mizzen CA. Site-specific regulation of histone H1 phosphorylation in pluripotent cell differentiation. Epigenetics Chromatin 2017; 10:29. [PMID: 28539972 PMCID: PMC5440973 DOI: 10.1186/s13072-017-0135-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 05/11/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Structural variation among histone H1 variants confers distinct modes of chromatin binding that are important for differential regulation of chromatin condensation, gene expression and other processes. Changes in the expression and genomic distributions of H1 variants during cell differentiation appear to contribute to phenotypic differences between cell types, but few details are known about the roles of individual H1 variants and the significance of their disparate capacities for phosphorylation. In this study, we investigated the dynamics of interphase phosphorylation at specific sites in individual H1 variants during the differentiation of pluripotent NT2 and mouse embryonic stem cells and characterized the kinases involved in regulating specific H1 variant phosphorylations in NT2 and HeLa cells. RESULTS Here, we show that the global levels of phosphorylation at H1.5-Ser18 (pS18-H1.5), H1.2/H1.5-Ser173 (pS173-H1.2/5) and H1.4-Ser187 (pS187-H1.4) are regulated differentially during pluripotent cell differentiation. Enrichment of pS187-H1.4 near the transcription start site of pluripotency factor genes in pluripotent cells is markedly reduced upon differentiation, whereas pS187-H1.4 levels at housekeeping genes are largely unaltered. Selective inhibition of CDK7 or CDK9 rapidly diminishes pS187-H1.4 levels globally and its enrichment at housekeeping genes, and similar responses were observed following depletion of CDK9. These data suggest that H1.4-S187 is a bona fide substrate for CDK9, a notion that is further supported by the significant colocalization of CDK9 and pS187-H1.4 to gene promoters in reciprocal re-ChIP analyses. Moreover, treating cells with actinomycin D to inhibit transcription and trigger the release of active CDK9/P-TEFb from 7SK snRNA complexes induces the accumulation of pS187-H1.4 at promoters and gene bodies. Notably, the levels of pS187-H1.4 enrichment after actinomycin D treatment or cell differentiation reflect the extent of CDK9 recruitment at the same loci. Remarkably, the global levels of H1.5-S18 and H1.2/H1.5-S173 phosphorylation are not affected by these transcription inhibitor treatments, and selective inhibition of CDK2 does not affect the global levels of phosphorylation at H1.4-S187 or H1.5-S18. CONCLUSIONS Our data provide strong evidence that H1 variant interphase phosphorylation is dynamically regulated in a site-specific and gene-specific fashion during pluripotent cell differentiation, and that enrichment of pS187-H1.4 at genes is positively related to their transcription. H1.4-S187 is likely to be a direct target of CDK9 during interphase, suggesting the possibility that this particular phosphorylation may contribute to the release of paused RNA pol II. In contrast, the other H1 variant phosphorylations we investigated appear to be mediated by distinct kinases and further analyses are needed to determine their functional significance.
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Affiliation(s)
- Ruiqi Liao
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, B107 Chemistry and Life Sciences Building, MC-123 601 S. Goodwin Ave., Urbana, IL 61801 USA
| | - Craig A Mizzen
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, B107 Chemistry and Life Sciences Building, MC-123 601 S. Goodwin Ave., Urbana, IL 61801 USA.,Institute for Genomic Biology, University of Illinois at Urbana Champaign, Urbana, IL 61801 USA
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11
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The pol II CTD: new twists in the tail. Nat Struct Mol Biol 2016; 23:771-7. [DOI: 10.1038/nsmb.3285] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 08/03/2016] [Indexed: 12/13/2022]
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12
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Romani B, Kamali Jamil R, Hamidi-Fard M, Rahimi P, Momen SB, Aghasadeghi MR, Allahbakhshi E. HIV-1 Vpr reactivates latent HIV-1 provirus by inducing depletion of class I HDACs on chromatin. Sci Rep 2016; 6:31924. [PMID: 27550312 PMCID: PMC4994036 DOI: 10.1038/srep31924] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 07/29/2016] [Indexed: 12/25/2022] Open
Abstract
HIV-1 Vpr is an accessory protein that induces proteasomal degradation of multiple proteins. We recently showed that Vpr targets class I HDACs on chromatin for proteasomal degradation. Here we show that Vpr induces degradation of HDAC1 and HDAC3 in HIV-1 latently infected J-Lat cells. Degradation of HDAC1 and HDAC3 was also observed on the HIV-1 LTR and as a result, markers of active transcription were recruited to the viral promoter and induced viral activation. Knockdown of HDAC1 and HDAC3 activated the latent HIV-1 provirus and complementation with HDAC3 inhibited Vpr-induced HIV-1 reactivation. Viral reactivation and degradation of HDAC1 and HDAC3 was conserved among Vpr proteins of HV-1 group M. Serum Vpr isolated from patients or the release of virion-incorporated Vpr from viral lysates also activated HIV-1 in latently infected cell lines and PBMCs from HIV-1 infected patients. Our results indicate that Vpr counteracts HIV-1 latency by inducing proteasomal degradation of HDAC1 and 3 leading to reactivation of the viral promoter.
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Affiliation(s)
- Bizhan Romani
- Cellular and Molecular Research Center (CMRC), Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences (AJUMS), Ahvaz, 61357-15794, Iran.,Department of Biology, Faculty of Science, University of Isfahan, Isfahan, 81746-73441, Iran
| | - Razieh Kamali Jamil
- Department of Human Viral Vaccines, Razi Vaccine and Serum Research Institute, Karaj, 31976-19751, Iran
| | - Mojtaba Hamidi-Fard
- Hepatitis and AIDS Department, Pasteur Institute of Iran, Tehran, 13169-43551, Iran
| | - Pooneh Rahimi
- Hepatitis and AIDS Department, Pasteur Institute of Iran, Tehran, 13169-43551, Iran
| | - Seyed Bahman Momen
- Pilot Biotechnology Department, Pasteur Institute of Iran, Tehran, 13169-43551, Iran
| | | | - Elham Allahbakhshi
- Cellular and Molecular Research Center (CMRC), Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences (AJUMS), Ahvaz, 61357-15794, Iran
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13
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Liao R, Mizzen CA. Interphase H1 phosphorylation: Regulation and functions in chromatin. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1859:476-85. [PMID: 26657617 DOI: 10.1016/j.bbagrm.2015.11.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 11/24/2015] [Accepted: 11/25/2015] [Indexed: 12/25/2022]
Abstract
Many metazoan cell types differentially express multiple non-allelic amino acid sequence variants of histone H1. Although early work revealed that H1 variants, collectively, are phosphorylated during interphase and mitosis, differences between individual H1 variants in the sites they possess for mitotic and interphase phosphorylation have been elucidated only relatively recently. Here, we review current knowledge on the regulation and function of interphase H1 phosphorylation, with a particular emphasis on how differences in interphase phosphorylation among the H1 variants of mammalian cells may enable them to have differential effects on transcription and other chromatin processes.
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Affiliation(s)
- Ruiqi Liao
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, USA
| | - Craig A Mizzen
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, USA; Institute for Genomic Biology, University of Illinois at Urbana Champaign, USA.
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14
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Sherrill-Mix S, Ocwieja KE, Bushman FD. Gene activity in primary T cells infected with HIV89.6: intron retention and induction of genomic repeats. Retrovirology 2015; 12:79. [PMID: 26377088 PMCID: PMC4574318 DOI: 10.1186/s12977-015-0205-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 08/28/2015] [Indexed: 02/07/2023] Open
Abstract
Background HIV infection has been reported to alter cellular gene activity, but published studies have commonly assayed transformed cell lines and lab-adapted HIV strains, yielding inconsistent results. Here we carried out a deep RNA-Seq analysis of primary human T cells infected with the low passage HIV isolate HIV89.6. Results Seventeen percent of cellular genes showed altered activity 48 h after infection. In a meta-analysis including four other studies, our data differed from studies of HIV infection in cell lines but showed more parallels with infections of primary cells. We found a global trend toward retention of introns after infection, suggestive of a novel cellular response to infection. HIV89.6 infection was also associated with activation of several human endogenous retroviruses (HERVs) and retrotransposons, of interest as possible novel antigens that could serve as vaccine targets. The most highly activated group of HERVs was a subset of the ERV-9. Analysis showed that activation was associated with a particular variant of ERV-9 long terminal repeats that contains an indel near the U3-R border. These data also allowed quantification of >70 splice forms of the HIV89.6 RNA and specified the main types of chimeric HIV89.6-host RNAs. Comparison to over 100,000 integration site sequences from the same infected cell populations allowed quantification of authentic versus artifactual chimeric reads, showing that 5′ read-in, splicing out of HIV89.6 from the D4 donor and 3′ read-through were the most common HIV89.6-host cell chimeric RNA forms. Conclusions Analysis of RNA abundance after infection of primary T cells with the low passage HIV89.6 isolate disclosed multiple novel features of HIV-host interactions, notably intron retention and induction of transcription of retrotransposons and endogenous retroviruses. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0205-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Scott Sherrill-Mix
- Department of Microbiology, Perelman School of Medicine at the University of Pennsylvania, 425 Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA, 19104, USA.
| | - Karen E Ocwieja
- Children's Hospital of Philadelphia, 3401 Civic Center Blvd., Philadelphia, PA, 19104, USA.
| | - Frederic D Bushman
- Department of Microbiology, Perelman School of Medicine at the University of Pennsylvania, 425 Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA, 19104, USA.
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15
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Li S, Kong L, Yu X, Zheng Y. Host-virus interactions: from the perspectives of epigenetics. Rev Med Virol 2014; 24:223-41. [PMID: 24677359 DOI: 10.1002/rmv.1783] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 12/23/2013] [Accepted: 01/16/2014] [Indexed: 12/25/2022]
Abstract
Chromatin structure and histone modifications play key roles in gene regulation. Some virus genomes are organized into chromatin-like structure, which undergoes different histone modifications facilitating complex functions in virus life cycles including replication. Here, we present a comprehensive summary of recent research in this field regarding the interaction between viruses and host epigenetic factors with emphasis on how chromatin modifications affect viral gene expression and virus infection. We also describe the strategies employed by viruses to manipulate the host epigenetic program to facilitate virus replication as well as the underlying mechanisms. Together, knowledge from this field not only generates novel insights into virus life cycles but may also have important therapeutic implications.
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Affiliation(s)
- Shanshan Li
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA, USA
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16
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Soe KC, Devaiah BN, Singer DS. Transcriptional coactivator CIITA, a functional homolog of TAF1, has kinase activity. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:1184-90. [PMID: 24036077 DOI: 10.1016/j.bbagrm.2013.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 09/03/2013] [Accepted: 09/04/2013] [Indexed: 11/26/2022]
Abstract
The Major Histocompatibility Complex (MHC) class II transactivator (CIITA) mediates activated immune responses and its deficiency results in the Type II Bare Lymphocyte Syndrome. CIITA is a transcriptional co-activator that regulates γ-interferon-activated transcription of MHC class I and class II genes. It is also a functional homolog of TAF1, a component of the general transcription factor complex TFIID. TAF1 and CIITA both possess intrinsic acetyltransferase (AT) activity that is required for transcription initiation. In response to induction by γ-interferon, CIITA and it's AT activity bypass the requirement for TAF1 AT activity. TAF1 also has kinase activity that is essential for its function. However, no similar activity has been identified for CIITA thus far. Here we report that CIITA, like TAF1, is a serine-threonine kinase. Its substrate specificity parallels, but does not duplicate, that of TAF1 in phosphorylating the TFIID component TAF7, the RAP74 subunit of the general transcription factor TFIIF and histone H2B. Like TAF1, CIITA autophosphorylates, affecting its interaction with TAF7. Additionally, CIITA phosphorylates histone H2B at Ser36, a target of TAF1 that is required for transcription during cell cycle progression and stress response. However, unlike TAF1, CIITA also phosphorylates all the other histones. The identification of this novel kinase activity of CIITA further clarifies its role as a functional homolog of TAF1 which may operate during stress and γ-IFN activated MHC gene transcription.
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Affiliation(s)
- Katherine C Soe
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA
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17
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Bagashev A, Fan S, Mukerjee R, Claudio PP, Chabrashvili T, Leng RP, Benchimol S, Sawaya BE. Cdk9 phosphorylates Pirh2 protein and prevents degradation of p53 protein. Cell Cycle 2013; 12:1569-77. [PMID: 23603988 DOI: 10.4161/cc.24733] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Several reports have pointed to the negative involvement of p53 in transcriptional regulation of the human immunodeficiency virus type 1 long-terminal repeat (HIV-1 LTR). We recently demonstrated that through their physical interaction, cdk9 phosphorylates p53 on Ser-392, leading to p53 stability and accumulation. As a result, p53 stalled transcriptional elongation of the HIV-1 LTR and significantly reduced HIV-1 replication in primary microglia and astrocytes. Therefore, we sought to identify the mechanisms used by cdk9 to allow this p53 function. Using western blot analysis, we found that cdk9 promotes inhibition and phosphorylation of Mdm2 on Ser-395, thus preventing degradation of p53, a protein that is directly involved in promoting p53 ubiquitination. On the other hand, we showed that cdk9 phosphorylates Pirh2 on Ser-211 and Thr-217 residues through their physical interaction. Phosphorylation of Pirh2 renders it inactive and may contribute to p53-inhibition of transcriptional elongation of the HIV-1 LTR. Hence, we suggest that phosphorylation of Pirh2 may be a novel target for the inhibition of HIV-1 gene expression.
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Affiliation(s)
- Asen Bagashev
- Molecular Studies of Neurodegenerative Diseases Lab, The Fels Institute for Cancer Research & Molecular Biology, Temple University School of Medicine, Philadelphia, PA, USA
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18
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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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19
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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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20
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Abstract
Thirteen years ago, human cyclin T1 was identified as part of the positive transcription elongation factor b (P-TEFb) and the long-sought host cofactor for the HIV-1 transactivator Tat. Recent years have brought new insights into the intricate regulation of P-TEFb function and its relationship with Tat, revealing novel mechanisms for controlling HIV transcription and fueling new efforts to overcome the barrier of transcriptional latency in eradicating HIV. Moreover, the improved understanding of HIV and Tat forms a basis for studying transcription elongation control in general. Here, we review advances in HIV transcription research with a focus on the growing family of cellular P-TEFb complexes, structural insights into the interactions between Tat, P-TEFb, and TAR RNA, and the multifaceted regulation of these interactions by posttranscriptional modifications of Tat.
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O'Brien SK, Knight KL, Rana TM. Phosphorylation of histone H1 by P-TEFb is a necessary step in skeletal muscle differentiation. J Cell Physiol 2011; 227:383-9. [PMID: 21503884 DOI: 10.1002/jcp.22797] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Positive transcription elongation factor b (P-TEFb), the complex of Cyclin T1 and CDK9, activates the transcription of many viral and eukaryotic genes at the point of mRNA elongation. The activity of P-TEFb has been implicated in the differentiation of a number of cell types, including skeletal muscle. In order to promote transcription, P-TEFb hyperphosphorylates RNA Pol II, thereby increasing its processivity. Our previous work identified histone H1 as a P-TEFb substrate during HIV-1 and immediate-early transcription. Here, we examine the role of P-TEFb phosphorylation of histone H1 during differentiation, using the myoblast cell line C2C12 as a model for skeletal muscle differentiation. We found that H1 phosphorylation is elevated in differentiating C2C12, and this phosphorylation is sensitive to P-TEFb inhibition. H1 phosphorylation was also necessary for the induction of three muscle marker genes that require P-TEFb for expression. Additionally, ChIP experiments demonstrate that H1 dissociates from muscle differentiation marker genes in C2C12 cells under active P-TEFb conditions. We determine that both P-TEFb activity and H1 phosphorylation are necessary for the full differentiation of C2C12 myoblasts into myotubes.
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Affiliation(s)
- Siobhan K O'Brien
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School Worcester, Worcester, Massachusetts, USA
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Węsierska-Gądek J, Kramer MP. The impact of multi-targeted cyclin-dependent kinase inhibition in breast cancer cells: clinical implications. Expert Opin Investig Drugs 2011; 20:1611-28. [PMID: 22017180 DOI: 10.1517/13543784.2011.628985] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The progression of the mammalian cell cycle is driven by the transient activation of complexes consisting of cyclins and cyclin-dependent kinases (CDKs). Loss of control over the cell cycle results in accelerated cell division and malignant transformation and can be caused by the upregulation of cyclins, the aberrant activation of CDKs or the inactivation of cellular CDK inhibitors. For these reasons, cell cycle regulators are regarded as very promising therapeutic targets for the treatment of human malignancies. AREAS COVERED This review covers the structures and anti-breast cancer activity of selected pharmacological pan-specific CDK inhibitors. Multi-targeted CDK inhibitors affect CDKs involved in the regulation of both cell cycle progression and transcriptional control. The inhibition of CDK7/CDK9 has a serious impact on the activity of RNA polymerase II; when its carboxy-terminal domain is unphosphorylated, it is unable to recruit the cofactors required for transcriptional elongation, resulting in a global transcriptional block. Multi-targeted inhibition of CDKs represses anti-apoptotic proteins and thus promotes the induction of apoptosis. Moreover, the inhibition of CDK7 in estrogen receptor (ER)-positive breast cancer cells prevents activating phosphorylation of ER-α. EXPERT OPINION These diverse modes of action make multi-targeted CDK inhibitors promising drugs for the treatment of breast cancers.
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Affiliation(s)
- Józefa Węsierska-Gądek
- Medical University of Vienna, Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Center, Cell Cycle Regulation Group, Borschkegasse 8a, 1090 Vienna, Austria.
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