1
|
Bromodomain and Extra-Terminal Inhibitor BMS-986158 Reverses Latent HIV-1 Infection In Vitro and Ex Vivo by Increasing CDK9 Phosphorylation and Recruitment. Pharmaceuticals (Basel) 2022; 15:ph15030338. [PMID: 35337136 PMCID: PMC8952190 DOI: 10.3390/ph15030338] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/03/2022] [Accepted: 03/08/2022] [Indexed: 02/01/2023] Open
Abstract
Latent reservoir persistence remains a major obstacle for curing human immunodeficiency virus type 1 (HIV-1) infection. Thus, strategies for the elimination of latent HIV-1 are urgently needed. As a bromodomain and extra-terminal (BET) inhibitor, BMS-986158 has been used in clinical trials for advanced solid tumors and hematological malignancies. Here, we found that BMS-986158 reactivated latent HIV-1 in three types of HIV-1 latency cells in vitro, and in combination antiretroviral therapy (cART)-treated patient-derived peripheral blood mononuclear cells ex vivo, without influencing global immune cell activation. BMS-986158 reactivated latent HIV-1 by increasing phosphorylation of CDK9 at Thr186 and promoting recruitment of CDK9 and RNA polymerase II to the HIV-1 long terminal repeat in J-Lat cells. Furthermore, BMS-986158 exerted strong synergism in reactivating latent HIV-1 when combined with prostratin and vorinostat and enhanced the antiviral activity of anti-HIV-1 drugs. Finally, BMS-986158 showed antiviral activity in an HIV-1 acute infection model, possibly by arresting the cell cycle in infected cells. Thus, these results suggest that BMS-986158 is a potential candidate for AIDS/HIV-1 therapy.
Collapse
|
2
|
Mele AR, Marino J, Dampier W, Wigdahl B, Nonnemacher MR. HIV-1 Tat Length: Comparative and Functional Considerations. Front Microbiol 2020; 11:444. [PMID: 32265877 PMCID: PMC7105873 DOI: 10.3389/fmicb.2020.00444] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 03/02/2020] [Indexed: 12/22/2022] Open
Affiliation(s)
- Anthony R Mele
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, United States.,Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Jamie Marino
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, United States.,Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Will Dampier
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, United States.,Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, United States.,School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, United States
| | - Brian Wigdahl
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, United States.,Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, United States.,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States
| | - Michael R Nonnemacher
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, United States.,Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, United States.,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States
| |
Collapse
|
3
|
Shadrina O, Garanina I, Korolev S, Zatsepin T, Van Assche J, Daouad F, Wallet C, Rohr O, Gottikh M. Analysis of RNA binding properties of human Ku protein reveals its interactions with 7SK snRNA and protein components of 7SK snRNP complex. Biochimie 2020; 171-172:110-123. [PMID: 32105815 DOI: 10.1016/j.biochi.2020.02.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/21/2020] [Indexed: 12/21/2022]
Abstract
Human Ku heterodimeric protein composed of Ku70 and Ku80 subunits plays an important role in the non-homologous end-joining DNA repair pathway as a sensor of double strand DNA breaks. Ku is also involved in numerous cellular processes, and in some of them it acts in an RNA-dependent manner. However, RNA binding properties of the human Ku have not been well studied. Here we have analyzed interactions of a recombinant Ku heterodimer with a set of RNAs of various structure as well as eCLIP (enhanced crosslinking and immunoprecipitation) data for human Ku70. As a result, we have proposed a consensus RNA structure preferable for the Ku binding that is a hairpin possessing a bulge just near GpG sequence-containing terminal loop. 7SK snRNA is a scaffold for a ribonucleoprotein complex (7SK snRNP), which is known to participate in transcription regulation. We have shown that the recombinant Ku specifically binds a G-rich loop of hairpin 1 within 7SK snRNA. Moreover, Ku protein has been co-precipitated from HEK 293T cells with endogenous 7SK snRNA and such proteins included in 7SK snRNP as HEXIM1, Cdk9 and CTIP2. Ku and Cdk9 binding is found to be RNA-independent, meanwhile HEXIM1 and Ku co-precipitation depended on the presence of intact 7SK snRNA. The latter result has been confirmed using recombinant HEXIM1 and Ku proteins. Colocalization of Ku and CTIP2 was additionally confirmed by confocal microscopy. These results allow us to propose human Ku as a new component of the 7SK snRNP complex.
Collapse
Affiliation(s)
- Olga Shadrina
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992, Moscow, Russia.
| | - Irina Garanina
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia
| | - Sergey Korolev
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992, Moscow, Russia
| | - Timofei Zatsepin
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Skolkovo Institute of Science and Technology, Skolkovo, 121205, Russia
| | - Jeanne Van Assche
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Fadoua Daouad
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Clementine Wallet
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Olivier Rohr
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Marina Gottikh
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992, Moscow, Russia
| |
Collapse
|
4
|
Clark E, Nava B, Caputi M. Tat is a multifunctional viral protein that modulates cellular gene expression and functions. Oncotarget 2018; 8:27569-27581. [PMID: 28187438 PMCID: PMC5432358 DOI: 10.18632/oncotarget.15174] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 01/24/2017] [Indexed: 12/02/2022] Open
Abstract
The human immunodeficiency virus type I (HIV-1) has developed several strategies to condition the host environment to promote viral replication and spread. Viral proteins have evolved to perform multiple functions, aiding in the replication of the viral genome and modulating the cellular response to the infection. Tat is a small, versatile, viral protein that controls transcription of the HIV genome, regulates cellular gene expression and generates a permissive environment for viral replication by altering the immune response and facilitating viral spread to multiple tissues. Studies carried out utilizing biochemical, cellular, and genomic approaches show that the expression and activity of hundreds of genes and multiple molecular networks are modulated by Tat via multiple mechanisms.
Collapse
Affiliation(s)
- Evan Clark
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| | - Brenda Nava
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| | - Massimo Caputi
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| |
Collapse
|
5
|
Liu Y, Nonnemacher MR, Alexaki A, Pirrone V, Banerjee A, Li L, Kilareski E, Wigdahl B. Functional Studies of CCAAT/Enhancer Binding Protein Site Located Downstream of the Transcriptional Start Site. Clin Med Insights Pathol 2017; 10:1179555717694556. [PMID: 29162980 PMCID: PMC5692137 DOI: 10.1177/1179555717694556] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 09/20/2016] [Indexed: 12/13/2022] Open
Abstract
Previous studies have identified a CCAAT/enhancer binding protein (C/EBP) site located downstream of the transcriptional start site (DS3). The role of the DS3 element with respect to HIV-1 transactivation by Tat and viral replication has not been characterized. We have demonstrated that DS3 was a functional C/EBPβ binding site and mutation of this site to the C/EBP knockout DS3-9C variant showed lower HIV-1 long terminal repeat (LTR) transactivation by C/EBPβ. However, it was able to exhibit similar or even higher transcription levels by Tat compared to the parental LTR. C/EBPβ and Tat together further enhanced the transcription level of the parental LAI-LTR and DS3-9C LTR, with higher levels in the DS3-9C LTR. HIV molecular clone viruses carrying the DS3-9C variant LTR demonstrated a decreased replication capacity and delayed rate of replication. These results suggest that DS3 plays a role in virus transcriptional initiation and provides new insight into C/EBP regulation of HIV-1.
Collapse
Affiliation(s)
- Yujie Liu
- Department of Microbiology and Immunology, Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Michael R Nonnemacher
- Department of Microbiology and Immunology, Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Aikaterini Alexaki
- Department of Microbiology and Immunology, Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Vanessa Pirrone
- Department of Microbiology and Immunology, Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Anupam Banerjee
- Department of Microbiology and Immunology, Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Luna Li
- Department of Microbiology and Immunology, Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Evelyn Kilareski
- Department of Microbiology and Immunology, Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Brian Wigdahl
- Department of Microbiology and Immunology, Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA.,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| |
Collapse
|
6
|
Kaminski R, Chen Y, Salkind J, Bella R, Young WB, Ferrante P, Karn J, Malcolm T, Hu W, Khalili K. Negative Feedback Regulation of HIV-1 by Gene Editing Strategy. Sci Rep 2016; 6:31527. [PMID: 27528385 PMCID: PMC4985742 DOI: 10.1038/srep31527] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/20/2016] [Indexed: 12/21/2022] Open
Abstract
The CRISPR/Cas9 gene editing method is comprised of the guide RNA (gRNA) to target a specific DNA sequence for cleavage and the Cas9 endonuclease for introducing breaks in the double-stranded DNA identified by the gRNA. Co-expression of both a multiplex of HIV-1-specific gRNAs and Cas9 in cells results in the modification and/or excision of the segment of viral DNA, leading to replication-defective virus. In this study, we have personalized the activity of CRISPR/Cas9 by placing the gene encoding Cas9 under the control of a minimal promoter of HIV-1 that is activated by the HIV-1 Tat protein. We demonstrate that functional activation of CRISPR/Cas9 by Tat during the course of viral infection excises the designated segment of the integrated viral DNA and consequently suppresses viral expression. This strategy was also used in a latently infected CD4+ T-cell model after treatment with a variety of HIV-1 stimulating agents including PMA and TSA. Controlled expression of Cas9 by Tat offers a new strategy for safe implementation of the Cas9 technology for ablation of HIV-1 at a very early stage of HIV-1 replication during the course of the acute phase of infection and the reactivation of silent proviral DNA in latently infected cells.
Collapse
Affiliation(s)
- Rafal Kaminski
- Department of Neuroscience Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor Philadelphia, PA 19140, USA
| | - Yilan Chen
- Department of Neuroscience Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor Philadelphia, PA 19140, USA
| | - Julian Salkind
- Department of Neuroscience Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor Philadelphia, PA 19140, USA
| | - Ramona Bella
- Department of Neuroscience Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor Philadelphia, PA 19140, USA
| | - Won-Bin Young
- Department of Radiology University of Pittsburgh School of Medicine Pittsburgh, PA 15219, USA
| | - Pasquale Ferrante
- Department of Neuroscience Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor Philadelphia, PA 19140, USA.,Microbiology and Clinical Microbiology, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Milan, Italy
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Thomas Malcolm
- Excision Biotherapeutics, Inc., 3624 Market Street, #514, Philadelphia, PA 19104, USA
| | - Wenhui Hu
- Department of Neuroscience Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor Philadelphia, PA 19140, USA
| | - Kamel Khalili
- Department of Neuroscience Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor Philadelphia, PA 19140, USA
| |
Collapse
|
7
|
López-Huertas MR, Li J, Zafar A, Rodríguez-Mora S, García-Domínguez C, Mateos E, Alcamí J, Rao S, Coiras M. PKCθ and HIV-1 Transcriptional Regulator Tat Co-exist at the LTR Promoter in CD4(+) T Cells. Front Immunol 2016; 7:69. [PMID: 26973648 PMCID: PMC4770193 DOI: 10.3389/fimmu.2016.00069] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 02/15/2016] [Indexed: 11/17/2022] Open
Abstract
PKCθ is essential for the activation of CD4+ T cells. Upon TCR/CD28 stimulation, PKCθ is phosphorylated and migrates to the immunological synapse, inducing the activation of cellular transcription factors such as NF-κB and kinases as ERK that are critical for HIV-1 replication. We previously demonstrated that PKCθ is also necessary for HIV-1 replication but the precise mechanism is unknown. Efficient HIV-1 transcription and elongation are absolutely dependent on the synergy between NF-κB and the viral regulator Tat. Tat exerts its function by binding a RNA stem-loop structure proximal to the viral mRNA cap site termed TAR. Besides, due to its effect on cellular metabolic pathways, Tat causes profound changes in infected CD4+ T cells such as the activation of NF-κB and ERK. We hypothesized that the aberrant upregulation of Tat-mediated activation of NF-κB and ERK occurred through PKCθ signaling. In fact, Jurkat TetOff cells with stable and doxycycline-repressible expression of Tat (Jurkat-Tat) expressed high levels of mRNA for PKCθ. In these cells, PKCθ located at the plasma membrane was phosphorylated at T538 residue in undivided cells, in the absence of stimulation. Treatment with doxycycline inhibited PKCθ phosphorylation in Jurkat-Tat, suggesting that Tat expression was directly related to the activation of PKCθ. Both NF-κB and Ras/Raf/MEK/ERK signaling pathway were significantly activated in Jurkat-Tat cells, and this correlated with high transactivation of HIV-1 LTR promoter. RNA interference for PKCθ inhibited NF-κB and ERK activity, as well as LTR-mediated transactivation even in the presence of Tat. In addition to Tat-mediated activation of PKCθ in the cytosol, we demonstrated by sequential ChIP that Tat and PKCθ coexisted in the same complex bound at the HIV-1 LTR promoter, specifically at the region containing TAR loop. In conclusion, PKCθ-Tat interaction seemed to be essential for HIV-1 replication in CD4+ T cells and could be used as a therapeutic target.
Collapse
Affiliation(s)
- María Rosa López-Huertas
- AIDS Immunopathology Unit, National Center of Microbiology, Instituto de Salud Carlos III , Madrid , Spain
| | - Jasmine Li
- Department of Microbiology and Immunology, The Doherty Institute for Infection and Immunity, University of Melbourne , Melbourne, VIC , Australia
| | - Anjum Zafar
- Biomedical Sciences, Faculty of Education, Science, Technology and Mathematics, University of Canberra , Canberra, ACT , Australia
| | - Sara Rodríguez-Mora
- AIDS Immunopathology Unit, National Center of Microbiology, Instituto de Salud Carlos III , Madrid , Spain
| | - Carlota García-Domínguez
- Functional Research Unit in Chronic Diseases, National Center of Microbiology, Instituto de Salud Carlos III , Madrid , Spain
| | - Elena Mateos
- AIDS Immunopathology Unit, National Center of Microbiology, Instituto de Salud Carlos III , Madrid , Spain
| | - José Alcamí
- AIDS Immunopathology Unit, National Center of Microbiology, Instituto de Salud Carlos III , Madrid , Spain
| | - Sudha Rao
- Biomedical Sciences, Faculty of Education, Science, Technology and Mathematics, University of Canberra , Canberra, ACT , Australia
| | - Mayte Coiras
- AIDS Immunopathology Unit, National Center of Microbiology, Instituto de Salud Carlos III , Madrid , Spain
| |
Collapse
|
8
|
Tang X, Liang Y, Liu X, Zhou S, Liu L, Zhang F, Xie C, Cai S, Wei J, Zhu Y, Hou W. PLGA-PEG Nanoparticles Coated with Anti-CD45RO and Loaded with HDAC Plus Protease Inhibitors Activate Latent HIV and Inhibit Viral Spread. NANOSCALE RESEARCH LETTERS 2015; 10:413. [PMID: 26489856 PMCID: PMC4614850 DOI: 10.1186/s11671-015-1112-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 10/09/2015] [Indexed: 05/21/2023]
Abstract
Activating HIV-1 proviruses in latent reservoirs combined with inhibiting viral spread might be an effective anti-HIV therapeutic strategy. Active specific delivery of therapeutic drugs into cells harboring latent HIV, without the use of viral vectors, is a critical challenge to this objective. In this study, nanoparticles of poly(lactic-co-glycolic acid)-polyethylene glycol diblock copolymers conjugated with anti-CD45RO antibody and loaded with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) and/or protease inhibitor nelfinavir (Nel) were tested for activity against latent virus in vitro. Nanoparticles loaded with SAHA, Nel, and SAHA + Nel were characterized in terms of size, surface morphology, zeta potential, entrapment efficiency, drug release, and toxicity to ACH-2 cells. We show that SAHA- and SAHA + Nel-loaded nanoparticles can target latently infected CD4(+) T-cells and stimulate virus production. Moreover, nanoparticles loaded with SAHA + NEL were capable of both activating latent virus and inhibiting viral spread. Taken together, these data demonstrate the potential of this novel reagent for targeting and eliminating latent HIV reservoirs.
Collapse
Affiliation(s)
- Xiaolong Tang
- Huainan First People's Hospital and First Affiliated Hospital of Medical College, Anhui University of Science and Technology, Huainan, 232001, China
- The State Key Laboratory of Virology, Life Sciences College, Wuhan University, Wuhan, 430072, China
| | - Yong Liang
- Clinical Laboratory, The Affiliated Huai'an Hospital of Xuzhou Medical College, Huai'an, 223002, China
| | - Xinkuang Liu
- Huainan First People's Hospital and First Affiliated Hospital of Medical College, Anhui University of Science and Technology, Huainan, 232001, China
| | - Shuping Zhou
- Huainan First People's Hospital and First Affiliated Hospital of Medical College, Anhui University of Science and Technology, Huainan, 232001, China
| | - Liang Liu
- Huainan First People's Hospital and First Affiliated Hospital of Medical College, Anhui University of Science and Technology, Huainan, 232001, China
| | - Fujina Zhang
- Huainan First People's Hospital and First Affiliated Hospital of Medical College, Anhui University of Science and Technology, Huainan, 232001, China
| | - Chunmei Xie
- School of Biotechnology, Southern Medical University, Guangzhou, 510515, China
| | - Shuyu Cai
- Huainan First People's Hospital and First Affiliated Hospital of Medical College, Anhui University of Science and Technology, Huainan, 232001, China
| | - Jia Wei
- Huainan First People's Hospital and First Affiliated Hospital of Medical College, Anhui University of Science and Technology, Huainan, 232001, China
| | - Yongqiang Zhu
- Department of Medical Genetics, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, People's Republic of China.
| | - Wei Hou
- The State Key Laboratory of Virology, Life Sciences College, Wuhan University, Wuhan, 430072, China.
| |
Collapse
|
9
|
Gordon N, Rosenblum R, Nussbaum-Shochat A, Eliahoo E, Amster-Choder O. A Search for Ribonucleic Antiterminator Sites in Bacterial Genomes: Not Only Antitermination? J Mol Microbiol Biotechnol 2015; 25:143-53. [PMID: 26159075 DOI: 10.1159/000375263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BglG/LicT-like proteins are transcriptional antiterminators that prevent termination of transcription at intrinsic terminators by binding to ribonucleic antiterminator (RAT) sites and stabilizing an RNA conformation which is mutually exclusive with the terminator structure. The known RAT sites, which are located in intergenic regions of sugar utilization operons, show low sequence conservation but significant structural analogy. To assess the prevalence of RATs in bacterial genomes, we employed bioinformatic tools that describe RNA motifs based on both sequence and structural constraints. Using descriptors with different stringency, we searched the genomes of Escherichiacoli K12, uropathogenic E. coli and Bacillus subtilis for putative RATs. Our search identified all known RATs and additional putative RAT elements. Surprisingly, most putative RATs do not overlap an intrinsic terminator and many reside within open reading frames (ORFs). The ability of one of the putative RATs, which is located within an antiterminator-encoding ORF and does not overlap a terminator, to bind to its cognate antiterminator protein in vitro and in vivo was confirmed experimentally. Our results suggest that the capacity of RAT elements has been exploited during evolution to mediate activities other than antitermination, for example control of transcription elongation or of RNA stability.
Collapse
Affiliation(s)
- Noa Gordon
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University Faculty of Medicine, Jerusalem, Israel
| | | | | | | | | |
Collapse
|
10
|
Lata S, Ali A, Sood V, Raja R, Banerjea AC. HIV-1 Rev downregulates Tat expression and viral replication via modulation of NAD(P)H:quinine oxidoreductase 1 (NQO1). Nat Commun 2015; 6:7244. [DOI: 10.1038/ncomms8244] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 04/22/2015] [Indexed: 12/30/2022] Open
|
11
|
Wang X, Wang P, Fu Z, Ji H, Qu X, Zeng H, Zhu X, Deng J, Lu P, Zha S, Song Z, Zhu H. Designed transcription activator-like effector proteins efficiently induced the expression of latent HIV-1 in latently infected cells. AIDS Res Hum Retroviruses 2015; 31:98-106. [PMID: 25403229 DOI: 10.1089/aid.2014.0121] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
HIV latency is the foremost barrier to clearing HIV infection from patients. Reactivation of latent HIV-1 represents a promising strategy to deplete these viral reservoirs. Here, we report a novel approach to reactivate latent HIV-1 provirus using artificially designed transcription activator-like effector (TALE) fusion proteins containing a DNA-binding domain specifically targeting the HIV-1 promoter and the herpes simplex virus-based transcriptional activator VP64 domain. We engineered four TALE genes (TALE1-4) encoding TALE proteins, each specifically targeting different 20-bp DNA sequences within the HIV-1 promoter, and we constructed four TALE-VP64 expression vectors corresponding to TALE1-4. We found that TALE1-VP64 effectively reactivated HIV-1 gene expression in latently infected C11 and A10.6 cells. We further confirmed that TALE1-VP64 reactivated latent HIV-1 via specific binding to the HIV-LTR promoter. Moreover, we also found that TALE1-VP64 did not affect cell proliferation or cell cycle distribution. Taken together, our data demonstrated that TALE1-VP64 can specifically and effectively reactivate latent HIV-1 transcription, suggesting that this strategy may provide a novel approach for anti-HIV-1 latency therapy in the future.
Collapse
Affiliation(s)
- Xiaohui Wang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Pengfei Wang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Zheng Fu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Haiyan Ji
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Xiying Qu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Hanxian Zeng
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Xiaoli Zhu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Junxiao Deng
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Panpan Lu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Shijun Zha
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Zhishuo Song
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| | - Huanzhang Zhu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, China
| |
Collapse
|
12
|
Ruiz A, Pauls E, Badia R, Riveira-Muñoz E, Clotet B, Ballana E, Esté JA. Characterization of the influence of mediator complex in HIV-1 transcription. J Biol Chem 2014; 289:27665-76. [PMID: 25100719 DOI: 10.1074/jbc.m114.570341] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
HIV-1 exploits multiple host proteins during infection. siRNA-based screenings have identified new proteins implicated in different pathways of the viral cycle that participate in a broad range of cellular functions. The human Mediator complex (MED) is composed of 28 elements and represents a fundamental component of the transcription machinery, interacting with the RNA polymerase II enzyme and regulating its ability to express genes. Here, we provide an evaluation of the MED activity on HIV replication. Knockdown of 9 out of 28 human MED proteins significantly impaired viral replication without affecting cell viability, including MED6, MED7, MED11, MED14, MED21, MED26, MED27, MED28, and MED30. Impairment of viral replication by MED subunits was at a post-integration step. Inhibition of early HIV transcripts was observed by siRNA-mediated knockdown of MED6, MED7, MED11, MED14, and MED28, specifically affecting the transcription of the nascent viral mRNA transactivation-responsive element. In addition, MED14 and MED30 were shown to have special relevance during the formation of unspliced viral transcripts (p < 0.0005). Knockdown of the selected MED factors compromised HIV transcription induced by Tat, with the strongest inhibitory effect shown by siMED6 and siMED14 cells. Co-immunoprecipitation experiments suggested physical interaction between MED14 and HIV-1 Tat protein. A better understanding of the mechanisms and factors controlling HIV-1 transcription is key to addressing the development of new strategies required to inhibit HIV replication or reactivate HIV-1 from the latent reservoirs.
Collapse
Affiliation(s)
- Alba Ruiz
- From the AIDS Research Institute-IrsiCaixa and AIDS Unit, Hospital Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Eduardo Pauls
- From the AIDS Research Institute-IrsiCaixa and AIDS Unit, Hospital Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Roger Badia
- From the AIDS Research Institute-IrsiCaixa and AIDS Unit, Hospital Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Eva Riveira-Muñoz
- From the AIDS Research Institute-IrsiCaixa and AIDS Unit, Hospital Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Bonaventura Clotet
- From the AIDS Research Institute-IrsiCaixa and AIDS Unit, Hospital Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Ester Ballana
- From the AIDS Research Institute-IrsiCaixa and AIDS Unit, Hospital Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - José A Esté
- From the AIDS Research Institute-IrsiCaixa and AIDS Unit, Hospital Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| |
Collapse
|
13
|
Van Lint C, Bouchat S, Marcello A. HIV-1 transcription and latency: an update. Retrovirology 2013; 10:67. [PMID: 23803414 PMCID: PMC3699421 DOI: 10.1186/1742-4690-10-67] [Citation(s) in RCA: 237] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 05/29/2013] [Indexed: 12/11/2022] Open
Abstract
Combination antiretroviral therapy, despite being potent and life-prolonging, is not curative and does not eradicate HIV-1 infection since interruption of treatment inevitably results in a rapid rebound of viremia. Reactivation of latently infected cells harboring transcriptionally silent but replication-competent proviruses is a potential source of persistent residual viremia in cART-treated patients. Although multiple reservoirs may exist, the persistence of resting CD4+ T cells carrying a latent infection represents a major barrier to eradication. In this review, we will discuss the latest reports on the molecular mechanisms that may regulate HIV-1 latency at the transcriptional level, including transcriptional interference, the role of cellular factors, chromatin organization and epigenetic modifications, the viral Tat trans-activator and its cellular cofactors. Since latency mechanisms may also operate at the post-transcriptional level, we will consider inhibition of nuclear RNA export and inhibition of translation by microRNAs as potential barriers to HIV-1 gene expression. Finally, we will review the therapeutic approaches and clinical studies aimed at achieving either a sterilizing cure or a functional cure of HIV-1 infection, with a special emphasis on the most recent pharmacological strategies to reactivate the latent viruses and decrease the pool of viral reservoirs.
Collapse
Affiliation(s)
- Carine Van Lint
- Université Libre de Bruxelles (ULB), Service of Molecular Virology, Institute of Molecular Biology and Medicine, 12, Rue des Profs Jeener et Brachet, 6041, Gosselies, Belgium.
| | | | | |
Collapse
|
14
|
Hong HW, Lee SW, Myung H. Induced degradation of Tat by nucleocapsid (NC) via the proteasome pathway and its effect on HIV transcription. Viruses 2013; 5:1143-52. [PMID: 23611845 PMCID: PMC3705270 DOI: 10.3390/v5041143] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/16/2013] [Accepted: 04/16/2013] [Indexed: 11/16/2022] Open
Abstract
Human Immunodeficiency Virus type 1 (HIV-1) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS). HIV-1 Tat protein upregulates transcriptional transactivation. The nucleocapsid protein NC of HIV-1 is a component of virion and plays a key role in genome packaging. Herein, we have demonstrated the interaction between NC and Tat by means of a yeast two-hybrid assay, GST pull-down analysis, co-immunoprecipitation and subcellular colocalization analysis. We observed that the level of Tat was significantly reduced in the presence of NC. But NC did not affect mRNA expression level of Tat. The level of Tat in the presence of NC was increased by treating cells with a proteasome inhibitor, MG132. The ubiquitination state of Tat was not seen to increase in the presence of NC, suggesting the proteasomal degradation was independent of ubiquitination. Lowered level of Tat in the presence of NC led to a decrease in Tat-mediated transcriptional transactivation.
Collapse
Affiliation(s)
- Hye-Won Hong
- Department of Bioscience and Biotechnology, Hankuk University of Foreign Studies, Yong-In, Gyung-Gi Do 449-791, Korea; E-Mail:
| | - Seong-Wook Lee
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yong-In, Gyung-Gi Do 448-701, Korea; E-Mail:
| | - Heejoon Myung
- Department of Bioscience and Biotechnology, Hankuk University of Foreign Studies, Yong-In, Gyung-Gi Do 449-791, Korea; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +82-31-330-4098; Fax: +82-31-330-4566
| |
Collapse
|
15
|
Kula A, Marcello A. Dynamic Post-Transcriptional Regulation of HIV-1 Gene Expression. BIOLOGY 2012; 1:116-33. [PMID: 24832221 PMCID: PMC4009772 DOI: 10.3390/biology1020116] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 06/15/2012] [Accepted: 06/18/2012] [Indexed: 01/08/2023]
Abstract
Gene expression of the human immunodeficiency virus type 1 (HIV-1) is a highly regulated process. Basal transcription of the integrated provirus generates early transcripts that encode for the viral products Tat and Rev. Tat promotes the elongation of RNA polymerase while Rev mediates the nuclear export of viral RNAs that contain the Rev-responsive RNA element (RRE). These RNAs are exported from the nucleus to allow expression of Gag-Pol and Env proteins and for the production of full-length genomic RNAs. A balance exists between completely processed mRNAs and RRE-containing RNAs. Rev functions as an adaptor that recruits cellular factors to re-direct singly spliced and unspliced viral RNAs to nuclear export. The aim of this review is to address the dynamic regulation of this post-transcriptional pathway in light of recent findings that implicate several novel cellular cofactors of Rev function.
Collapse
Affiliation(s)
- Anna Kula
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano, Trieste 99 34012, Italy.
| | - Alessandro Marcello
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano, Trieste 99 34012, Italy.
| |
Collapse
|
16
|
Abstract
Transcription by RNA polymerase II is the process that copies DNA into RNA leading to the expression of a specific gene. Averaged estimates of polymerase elongation rates in mammalian cells have been shown to vary between 1 and 4 kilobases per minute. However, recent advances in live cell imaging allowed direct measurements of RNA biogenesis from a single gene exceeded 50 kb·min(-1) . This unexpected finding opens novel and intriguing perspectives on the control of metazoan transcription.
Collapse
Affiliation(s)
- Alessandro Marcello
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
| |
Collapse
|
17
|
Ka WH, Jeong YY, You JC. Identification of the HIV-1 packaging RNA sequence (Ψ) as a major determinant for the translation inhibition conferred by the HIV-1 5' UTR. Biochem Biophys Res Commun 2011; 417:501-7. [PMID: 22166215 DOI: 10.1016/j.bbrc.2011.11.149] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 11/29/2011] [Indexed: 10/14/2022]
Abstract
The HIV-1 5' untranslated region (UTR) contains conserved sequences and unique structural motifs associated with many steps in virus replication. Because unspliced HIV mRNA containing the full-length UTR serves as a template for replication and transcription as well as packaging genomic RNA into virion, it has been postulated that the UTR may play a role in translational regulation. However, the effect and the region(s) responsible for translation control remain controversial. We used deletion mutations of the 5' UTR region in both cell-based and in vitro assays to determine if secondary structural elements within the 5' UTR confer translation inhibition, and to identify which of these elements are involved. The results indicate clearly that the entire HIV-1 5' UTR confers translation inhibition in vitro and in cells; the Psi (Ψ) region specifically has the most translation inhibitory activity among the highly-structured elements in the HIV-1 5' UTR. Moreover, it was found that the SL4 structure in the Psi (Ψ) region is the major determinant of translation inhibition, and that elimination of the SL4 RNA sequence led to increased translation. The results suggest a functional role for the Psi element and the SL4 structure in the translational control of HIV-1 full-length mRNA.
Collapse
Affiliation(s)
- Won Hye Ka
- Department of Pathology, School of Medicine, The Catholic University of Korea, Seoul, South Korea
| | | | | |
Collapse
|
18
|
Maiuri P, Knezevich A, De Marco A, Mazza D, Kula A, McNally JG, Marcello A. Fast transcription rates of RNA polymerase II in human cells. EMBO Rep 2011; 12:1280-5. [PMID: 22015688 DOI: 10.1038/embor.2011.196] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 08/19/2011] [Accepted: 09/02/2011] [Indexed: 11/09/2022] Open
Abstract
Averaged estimates of RNA polymerase II (RNAPII) elongation rates in mammalian cells have been shown to range between 1.3 and 4.3 kb min(-1). In this work, nascent RNAs from an integrated human immunodeficiency virus type 1-derived vector were detectable at the single living cell level by fluorescent RNA tagging. At steady state, a constant number of RNAs was measured corresponding to a minimal density of polymerases with negligible fluctuations over time. Recovery of fluorescence after photobleaching was complete within seconds, indicating a high rate of RNA biogenesis. The calculated transcription rate above 50 kb min(-1) points towards a wide dynamic range of RNAPII velocities in living cells.
Collapse
Affiliation(s)
- Paolo Maiuri
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, Trieste 34149, Italy.
| | | | | | | | | | | | | |
Collapse
|
19
|
Abstract
The current anti-HIV treatments fail to completely eradicate the virus in HIV-infected individuals, mainly as a result of a small pool of latently infected cells. This issue, together with the emergence of multidrug-resistant viruses, clearly highlights the need to find additional strategies. An overview of the Tat-mediated transcription inhibitors 6-desfluoroquinolones (6-DFQs), identified by our group, is given in this review along with a critical appraisal of their advantages and drawbacks. Attempts are also made to place them within the context of new potential anti-HIV therapeutics. Due to their innovative mechanism of action, the 6-DFQs could be interesting candidates for use in association with the currently used cocktail of drugs. Their potential as antivirals deserves further investigation.
Collapse
|
20
|
Colin L, Vandenhoudt N, de Walque S, Van Driessche B, Bergamaschi A, Martinelli V, Cherrier T, Vanhulle C, Guiguen A, David A, Burny A, Herbein G, Pancino G, Rohr O, Van Lint C. The AP-1 binding sites located in the pol gene intragenic regulatory region of HIV-1 are important for viral replication. PLoS One 2011; 6:e19084. [PMID: 21526160 PMCID: PMC3079759 DOI: 10.1371/journal.pone.0019084] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 03/15/2011] [Indexed: 01/06/2023] Open
Abstract
Our laboratory has previously identified an important intragenic region in the human immunodeficiency virus type 1 (HIV-1) genome, whose complete functional unit is composed of the 5103 fragment, the DNaseI-hypersensitive site HS7 and the 5105 fragment. These fragments (5103 and 5105) both exhibit a phorbol 12-myristate 13-acetate (PMA)-inducible enhancer activity on the herpes simplex virus thymidine kinase promoter. Here, we characterized the three previously identified AP-1 binding sites of fragment 5103 by showing the PMA-inducible in vitro binding and in vivo recruitment of c-Fos, JunB and JunD to this fragment located at the end of the pol gene. Functional analyses demonstrated that the intragenic AP-1 binding sites are fully responsible for the PMA-dependent enhancer activity of fragment 5103. Moreover, infection of T-lymphoid Jurkat and promonocytic U937 cells with wild-type and mutant viruses demonstrated that mutations of the intragenic AP-1 sites individually or in combination altered HIV-1 replication. Importantly, mutations of the three intragenic AP-1 sites led to a decreased in vivo recruitment of RNA polymerase II to the viral promoter, strongly supporting that the deleterious effect of these mutations on viral replication occurs, at least partly, at the transcriptional level. Single-round infections of monocyte-derived macrophages confirmed the importance of intragenic AP-1 sites for HIV-1 infectivity.
Collapse
Affiliation(s)
- Laurence Colin
- Laboratoire de Virologie Moléculaire, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Nathalie Vandenhoudt
- Laboratoire de Virologie Moléculaire, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Stéphane de Walque
- Laboratoire de Virologie Moléculaire, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Benoît Van Driessche
- Laboratoire de Virologie Moléculaire, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Anna Bergamaschi
- Institut Pasteur, Unité de Régulation des Infections Rétrovirales, Paris, France
| | - Valérie Martinelli
- Laboratoire de Virologie Moléculaire, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Thomas Cherrier
- IUT Louis Pasteur de Schiltigheim, University of Strasbourg, Schiltigheim, France
| | - Caroline Vanhulle
- Laboratoire de Virologie Moléculaire, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Allan Guiguen
- Laboratoire de Virologie Moléculaire, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Annie David
- Institut Pasteur, Unité de Régulation des Infections Rétrovirales, Paris, France
| | - Arsène Burny
- Laboratoire de Virologie Moléculaire, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Georges Herbein
- Department of Virology, EA3186, IFR133, Franche-Comte University, Hôpital Saint-Jacques, Besançon, France
| | - Gianfranco Pancino
- Institut Pasteur, Unité de Régulation des Infections Rétrovirales, Paris, France
| | - Olivier Rohr
- IUT Louis Pasteur de Schiltigheim, University of Strasbourg, Schiltigheim, France
| | - Carine Van Lint
- Laboratoire de Virologie Moléculaire, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| |
Collapse
|
21
|
Abstract
The lack of an efficacious HIV-1 vaccine and the continued emergence of drug-resistant HIV-1 strains have pushed the research community to explore novel avenues for AIDS therapy. Over the last decade, one new avenue that has been realized involves cellular HIV-1 restriction factors, defined as host cellular proteins or factors that restrict or inhibit HIV-1 replication. Many of these factors are interferon-induced and inhibit specific stages of the HIV-1 lifecycle that are not targeted by current AIDS therapies. Our understanding of the molecular mechanisms underlying HIV-1 restriction is far from complete, but our current knowledge of these factors offers hope for the future development of novel therapeutic ideas.
Collapse
Affiliation(s)
- Stephen D Barr
- Department of Microbiology & Immunology, The University of Western Ontario, London, ON, Canada
| |
Collapse
|
22
|
Maiuri P, Knezevich A, Bertrand E, Marcello A. Real-time imaging of the HIV-1 transcription cycle in single living cells. Methods 2010; 53:62-7. [PMID: 20600934 DOI: 10.1016/j.ymeth.2010.06.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 03/29/2010] [Accepted: 06/19/2010] [Indexed: 01/09/2023] Open
Abstract
The dynamic nature of cellular processes is emerging as an important modulator of physiological and pathological events. The key event in the life cycle of the human immunodeficiency virus type 1 (HIV-1) is transcription: it controls both viral gene expression and the latent phenotype. The basal transcription machinery and cellular and viral regulatory elements are dynamically recruited to the proviral DNA embedded into chromatin and to newly synthesized viral RNA. Their interactions determine fundamental steps, such as RNA polymerase recruitment, initiation, elongation, splicing, termination, and processing of pre-mRNA. The study of these events requires a novel armamentarium of techniques for live-cell imaging and fluorescence tagging of proteins and nucleic acids. The final outcome should not be only a descriptive view of the process but, most importantly, a quantitative analysis of the kinetics involved. Here, we provide an overview of the methodologies available for fluorescent labeling proteins and nucleic acids in live-cell imaging. We also describe the concept of fluorescent recovery after photobleaching (FRAP) and how it can be used to obtain information about HIV RNA transcription dynamics in living cells.
Collapse
Affiliation(s)
- Paolo Maiuri
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano, 99, 34012 Trieste, Italy
| | | | | | | |
Collapse
|
23
|
Hapgood JP, Tomasicchio M. Modulation of HIV-1 virulence via the host glucocorticoid receptor: towards further understanding the molecular mechanisms of HIV-1 pathogenesis. Arch Virol 2010; 155:1009-19. [PMID: 20446002 DOI: 10.1007/s00705-010-0678-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 03/26/2010] [Indexed: 10/19/2022]
Abstract
The glucocorticoid receptor (GR) is a steroid receptor that regulates diverse functions, which include the immune response. In humans, the GR acts via binding to cortisol, resulting in the transcriptional modulation of key host genes. Several lines of evidence suggest that the host GR could be a key protein exploited by HIV at multiple levels to ensure its pathogenic success. Endogenous and therapeutic glucocorticoids play important roles in patients with HIV due to their well-established effects on immune function. AIDS patients develop glucocorticoid hypersensitivity, consistent with a mechanism involving an HIV-1-induced increase in expression or activity of the GR. Both the HIV-1 accessory protein Vpr and the host GR affect transcription of viral proteins from the long terminal repeat (LTR) region of the HIV-1 promoter. In addition, Vpr modulates host GR function to affect transcription of host genes, most likely via direct interaction with the GR. Vpr appears to regulate GR function by acting as a co-activator for the GR. Since both the GR and Vpr are involved in apoptosis in T cells and dendritic cells, crosstalk between these proteins may also regulate apoptosis in these and other cells. Given that cortisol is not the only ligand that activates the GR, other endogenous as well as synthetic GR ligands such as progestins may also modulate HIV pathogenesis, in particular in the cervicovaginal environment. Investigating the molecular determinants, ligand-selectivity and role in HIV pathogenesis of the GR-Vpr interaction may lead to new strategies for development of anti-HIV drugs.
Collapse
Affiliation(s)
- Janet Patricia Hapgood
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa.
| | | |
Collapse
|
24
|
Massari S, Daelemans D, Barreca ML, Knezevich A, Sabatini S, Cecchetti V, Marcello A, Pannecouque C, Tabarrini O. A 1,8-naphthyridone derivative targets the HIV-1 Tat-mediated transcription and potently inhibits the HIV-1 replication. J Med Chem 2010; 53:641-8. [PMID: 19958026 DOI: 10.1021/jm901211d] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The emergence of multidrug resistant HIV-1 strains and the inability of the HAART to eradicate HIV-1 virus from infected patients demand new drugs able to interfere with an alternative step of the replicative cycle. The naphthyridone 3 (HM13N), described in the present study, is a promising anti-HIV agent due to its ability to inhibit the HIV-1 Tat-mediated transcription and the potent antiviral activity observed in acutely, chronically, and latently infected cells. The absence of any tendency to select for resistance mutations in vitro adds to the potential clinical value of this type of compounds, especially as these compounds are drug-like and obey the Lipinski rules.
Collapse
Affiliation(s)
- Serena Massari
- Dipartimento di Chimica e Tecnologia del Farmaco, Università di Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
López-Huertas MR, Callejas S, Abia D, Mateos E, Dopazo A, Alcamí J, Coiras M. Modifications in host cell cytoskeleton structure and function mediated by intracellular HIV-1 Tat protein are greatly dependent on the second coding exon. Nucleic Acids Res 2010; 38:3287-307. [PMID: 20139419 PMCID: PMC2879518 DOI: 10.1093/nar/gkq037] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) regulator Tat is essential for viral replication because it achieves complete elongation of viral transcripts. Tat can be released to the extracellular space and taken up by adjacent cells, exerting profound cytoskeleton rearrangements that lead to apoptosis. In contrast, intracellular Tat has been described as protector from apoptosis. Tat gene is composed by two coding exons that yield a protein of 101 amino acids (aa). First exon (1–72aa) is sufficient for viral transcript elongation and second exon (73–101 aa) appears to contribute to non-transcriptional functions. We observed that Jurkat cells stably expressing intracellular Tat101 showed gene expression deregulation 4-fold higher than cells expressing Tat72. Functional experiments were performed to evaluate the effect of this deregulation. First, NF-κB-, NF-AT- and Sp1-dependent transcriptional activities were greatly enhanced in Jurkat-Tat101, whereas Tat72 induced milder but efficient activation. Second, cytoskeleton-related functions as cell morphology, proliferation, chemotaxis, polarization and actin polymerization were deeply altered in Jurkat-Tat101, but not in Jurkat-Tat72. Finally, expression of several cell surface receptors was dramatically impaired by intracellular Tat101 but not by Tat72. Consequently, these modifications were greatly dependent on Tat second exon and they could be related to the anergy observed in HIV-1-infected T cells.
Collapse
Affiliation(s)
- M R López-Huertas
- AIDS Immunopathology Unit, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain
| | | | | | | | | | | | | |
Collapse
|
26
|
Amino acids special issue 'Protein interactions in the virus-host relationship'. Amino Acids 2009; 41:1135-6. [PMID: 20020162 DOI: 10.1007/s00726-009-0441-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 12/01/2009] [Indexed: 10/20/2022]
|
27
|
Subcellular localization of the interaction between the human immunodeficiency virus transactivator Tat and the nucleosome assembly protein 1. Amino Acids 2009; 38:1583-93. [DOI: 10.1007/s00726-009-0378-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 10/14/2009] [Indexed: 10/20/2022]
|
28
|
Role of Tat protein in HIV neuropathogenesis. Neurotox Res 2009; 16:205-20. [PMID: 19526283 DOI: 10.1007/s12640-009-9047-8] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 03/09/2009] [Accepted: 03/09/2009] [Indexed: 12/13/2022]
Abstract
The Tat protein of the human immunodeficiency virus (HIV) has been implicated in the pathophysiology of the neurocognitive deficits associated with HIV infection. This is the earliest protein to be produced by the proviral DNA in the infected cell. The protein not only drives the regulatory regions of the virus but may also be actively released from the cell and then interact with the cell surface receptors of other uninfected cells in the brain leading to cellular dysfunction. It may also be taken up by these cells and can then activate a number of host genes. The Tat protein is highly potent and has the unique ability to travel along neuronal pathways. Importantly, its production is not impacted by the use of antiretroviral drugs once the proviral DNA has been formed. This article reviews the pleomorphic actions of Tat protein and the evidence supporting its central role in the neuropathogenesis of the HIV infection.
Collapse
|
29
|
Abstract
A broad range of nanomedicines is being developed to improve drug delivery for CNS disorders. The structure of the blood-brain barrier (BBB), the presence of efflux pumps and the expression of metabolic enzymes pose hurdles for drug-brain entry. Nanoformulations can circumvent the BBB to improve CNS-directed drug delivery by affecting such pumps and enzymes. Alternatively, they can be optimized to affect their size, shape, and protein and lipid coatings to facilitate drug uptake, release and ingress across the barrier. This is important as the brain is a sanctuary for a broad range of pathogens including HIV-1. Improved drug delivery to the CNS would affect pharmacokinetic and drug biodistribution properties. This article focuses on how nanotechnology can serve to improve the delivery of antiretroviral medicines, termed nanoART, across the BBB and affect the biodistribution and clinical benefit for HIV-1 disease.
Collapse
Affiliation(s)
- Ari Nowacek
- Department of Pharmacology & Experimental Neuroscience, Center for Neurovirology & Neurodegenerative Disorders, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | | |
Collapse
|
30
|
Transcriptional competence of the integrated HIV-1 provirus at the nuclear periphery. EMBO J 2009; 28:2231-43. [PMID: 19478796 DOI: 10.1038/emboj.2009.141] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 04/29/2009] [Indexed: 11/08/2022] Open
Abstract
Spatial distribution of genes within the nucleus contributes to transcriptional control, allowing optimal gene expression as well as constitutive or regulated gene repression. Human immunodeficiency virus type 1 (HIV-1) integrates into host chromatin to transcribe and replicate its genome. Lymphocytes harbouring a quiescent but inducible provirus are a challenge to viral eradication in infected patients undergoing antiviral therapy. Therefore, our understanding of the contribution of sub-nuclear positioning to viral transcription may also have far-reaching implications in the pathology of the infection. To gain an insight into the conformation of chromatin at the site of HIV-1 integration, we investigated lymphocytes carrying a single latent provirus. In the silenced state, the provirus was consistently found at the nuclear periphery, associated in trans with a pericentromeric region of chromosome 12 in a significant number of quiescent cells. After induction of the transcription, this association was lost, although the location of the transcribing provirus remained peripheral. These results, extended to several other cell clones, unveil a novel mechanism of transcriptional silencing involved in HIV-1 post-transcriptional latency and reinforce the notion that gene transcription may also occur at the nuclear periphery.
Collapse
|
31
|
Faller E, Kakal J, Kumar R, MacPherson P. IL-7 and the HIV Tat protein act synergistically to down-regulate CD127 expression on CD8 T cells. Int Immunol 2009; 21:203-16. [DOI: 10.1093/intimm/dxn140] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
|
32
|
De Marco A, Biancotto C, Knezevich A, Maiuri P, Vardabasso C, Marcello A. Intragenic transcriptional cis-activation of the human immunodeficiency virus 1 does not result in allele-specific inhibition of the endogenous gene. Retrovirology 2008; 5:98. [PMID: 18983639 PMCID: PMC2586024 DOI: 10.1186/1742-4690-5-98] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Accepted: 11/04/2008] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND The human immunodeficiency virus type 1 (HIV-1) favors integration in active genes of host chromatin. It is believed that transcriptional interference of the viral promoter over the endogenous gene or vice versa might occur with implications in HIV-1 post-integrative transcriptional latency. RESULTS In this work a cell line has been transduced with a HIV-based vector and selected for Tat-inducible expression. These cells were found to carry a single silent integration in sense orientation within the second intron of the HMBOX1 gene. The HIV-1 Tat transactivator induced the viral LTR and repressed HMBOX1 expression independently of vector integration. Instead, single-cell quantitative in situ hybridization revealed that allele-specific transcription of HMBOX1 carrying the integrated provirus was not affected by the transactivation of the viral LTR in cis. CONCLUSION A major observation of the work is that the HIV-1 genome has inserted in genes that are also repressed by Tat and this could be an advantage for the virus during transcriptional reactivation. In addition, it has also been observed that transcription of the provirus and of the endogenous gene in which it is integrated may coexist at the same time in the same genomic location.
Collapse
Affiliation(s)
- Alex De Marco
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
| | | | | | | | | | | |
Collapse
|
33
|
CDK13, a new potential human immunodeficiency virus type 1 inhibitory factor regulating viral mRNA splicing. J Virol 2008; 82:7155-66. [PMID: 18480452 DOI: 10.1128/jvi.02543-07] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Tat is a 14-kDa viral protein that acts as a potent transactivator by binding to the transactivation-responsive region, a structured RNA element located at the 5' end of all HIV-1 transcripts. Tat transactivates viral gene expression by inducing the phosphorylation of the C-terminal domain of RNA polymerase II through several Tat-activated kinases and by recruiting chromatin-remodeling complexes and histone-modifying enzymes to the HIV-1 long terminal repeat. Histone acetyltransferases, including p300 and hGCN5, not only acetylate histones but also acetylate Tat at lysine positions 50 and 51 in the arginine-rich motif. Acetylated Tat at positions 50 and 51 interacts with a specialized protein module, the bromodomain, and recruits novel factors having this particular domain, such as P/CAF and SWI/SNF. In addition to having its effect on transcription, Tat has been shown to be involved in splicing. In this study, we demonstrate that Tat interacts with cyclin-dependent kinase 13 (CDK13) both in vivo and in vitro. We also found that CDK13 increases HIV-1 mRNA splicing and favors the production of the doubly spliced protein Nef. In addition, we demonstrate that CDK13 acts as a possible restriction factor, in that its overexpression decreases the production of the viral proteins Gag and Env and subsequently suppresses virus production. Using small interfering RNA against CDK13, we show that silencing of CDK13 leads to a significant increase in virus production. Finally, we demonstrate that CDK13 mediates its effect on splicing through the phosphorylation of ASF/SF2.
Collapse
|
34
|
Boireau S, Maiuri P, Basyuk E, de la Mata M, Knezevich A, Pradet-Balade B, Bäcker V, Kornblihtt A, Marcello A, Bertrand E. The transcriptional cycle of HIV-1 in real-time and live cells. ACTA ACUST UNITED AC 2007; 179:291-304. [PMID: 17954611 PMCID: PMC2064765 DOI: 10.1083/jcb.200706018] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
RNA polymerase II (RNAPII) is a fundamental enzyme, but few studies have analyzed its activity in living cells. Using human immunodeficiency virus (HIV) type 1 reporters, we study real-time messenger RNA (mRNA) biogenesis by photobleaching nascent RNAs and RNAPII at specific transcription sites. Through modeling, the use of mutant polymerases, drugs, and quantitative in situ hybridization, we investigate the kinetics of the HIV-1 transcription cycle. Initiation appears efficient because most polymerases demonstrate stable gene association. We calculate an elongation rate of approximately 1.9 kb/min, and, surprisingly, polymerases remain at transcription sites 2.5 min longer than nascent RNAs. With a total polymerase residency time estimated at 333 s, 114 are assigned to elongation, and 63 are assigned to 3′-end processing and/or transcript release. However, mRNAs were released seconds after polyadenylation onset, and analysis of polymerase density by chromatin immunoprecipitation suggests that they pause or lose processivity after passing the polyA site. The strengths and limitations of this kinetic approach to analyze mRNA biogenesis in living cells are discussed.
Collapse
Affiliation(s)
- Stéphanie Boireau
- Institute of Molecular Genetics of Montpellier, Unité Mixte de Recherche 5535, Centre National de la Recherche Scientifique, 34293 Montpellier, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Gendron K, Charbonneau J, Dulude D, Heveker N, Ferbeyre G, Brakier-Gingras L. The presence of the TAR RNA structure alters the programmed -1 ribosomal frameshift efficiency of the human immunodeficiency virus type 1 (HIV-1) by modifying the rate of translation initiation. Nucleic Acids Res 2007; 36:30-40. [PMID: 17984074 PMCID: PMC2248755 DOI: 10.1093/nar/gkm906] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
HIV-1 uses a programmed -1 ribosomal frameshift to synthesize the precursor of its enzymes, Gag-Pol. The frameshift efficiency that is critical for the virus replication, is controlled by an interaction between the ribosome and a specific structure on the viral mRNA, the frameshift stimulatory signal. The rate of cap-dependent translation initiation is known to be altered by the TAR RNA structure, present at the 5' and 3' end of all HIV-1 mRNAs. Depending upon its concentration, TAR activates or inhibits the double-stranded RNA-dependent protein kinase (PKR). We investigated here whether changes in translation initiation caused by TAR affect HIV-1 frameshift efficiency. CD4+ T cells and 293T cells were transfected with a dual-luciferase construct where the firefly luciferase expression depends upon the HIV-1 frameshift. Translation initiation was altered by adding TAR in cis or trans of the reporter mRNA. We show that HIV-1 frameshift efficiency correlates negatively with changes in the rate of translation initiation caused by TAR and mediated by PKR. A model is presented where changes in the rate of initiation affect the probability of frameshifting by altering the distance between elongating ribosomes on the mRNA, which influences the frequency of encounter between these ribosomes and the frameshift stimulatory signal.
Collapse
Affiliation(s)
- Karine Gendron
- Département de Biochimie, Université de Montréal, Montréal, Québec, Canada
| | | | | | | | | | | |
Collapse
|
36
|
Molecular basis of the internalization of bovine immunodeficiency virus Tat protein. Virus Genes 2007; 36:85-94. [DOI: 10.1007/s11262-007-0137-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Accepted: 07/02/2007] [Indexed: 10/22/2022]
|
37
|
Molle D, Maiuri P, Boireau S, Bertrand E, Knezevich A, Marcello A, Basyuk E. A real-time view of the TAR:Tat:P-TEFb complex at HIV-1 transcription sites. Retrovirology 2007; 4:36. [PMID: 17537237 PMCID: PMC1904240 DOI: 10.1186/1742-4690-4-36] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Accepted: 05/30/2007] [Indexed: 11/23/2022] Open
Abstract
HIV-1 transcription is tightly regulated: silent in long-term latency and highly active in acutely-infected cells. Transcription is activated by the viral protein Tat, which recruits the elongation factor P-TEFb by binding the TAR sequence present in nascent HIV-1 RNAs. In this study, we analyzed the dynamic of the TAR:Tat:P-TEFb complex in living cells, by performing FRAP experiments at HIV-1 transcription sites. Our results indicate that a large fraction of Tat present at these sites is recruited by Cyclin T1. We found that in the presence of Tat, Cdk9 remained bound to nascent HIV-1 RNAs for 71s. In contrast, when transcription was activated by PMA/ionomycin, in the absence of Tat, Cdk9 turned-over rapidly and resided on the HIV-1 promoter for only 11s. Thus, the mechanism of trans-activation determines the residency time of P-TEFb at the HIV-1 gene, possibly explaining why Tat is such a potent transcriptional activator. In addition, we observed that Tat occupied HIV-1 transcription sites for 55s, suggesting that the TAR:Tat:P-TEFb complex dissociates from the polymerase following transcription initiation, and undergoes subsequent cycles of association/dissociation.
Collapse
Affiliation(s)
- Dorothée Molle
- IGMM-CNRS UMR 5535, 1919, route de Mende, 34293 Montpellier, France
| | - Paolo Maiuri
- Laboratory of Molecular Virology, ICGEB, Padriciano 99, 34012 Trieste, Italy
| | | | - Edouard Bertrand
- IGMM-CNRS UMR 5535, 1919, route de Mende, 34293 Montpellier, France
| | - Anna Knezevich
- Laboratory of Molecular Virology, ICGEB, Padriciano 99, 34012 Trieste, Italy
| | - Alessandro Marcello
- Laboratory of Molecular Virology, ICGEB, Padriciano 99, 34012 Trieste, Italy
| | - Eugenia Basyuk
- IGMM-CNRS UMR 5535, 1919, route de Mende, 34293 Montpellier, France
| |
Collapse
|
38
|
Ramírez YJP, Tasciotti E, Gutierrez-Ortega A, Donayre Torres AJ, Olivera Flores MT, Giacca M, Gómez Lim MA. Fruit-specific expression of the human immunodeficiency virus type 1 tat gene in tomato plants and its immunogenic potential in mice. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 14:685-92. [PMID: 17460112 PMCID: PMC1951073 DOI: 10.1128/cvi.00028-07] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The human immunodeficiency virus type 1 (HIV-1) Tat protein is considered a potential candidate vaccine antigen. In an effort to design a strategy for noninvasive vaccination against HIV-1, we developed transgenic tomatoes expressing the Tat protein. Two independent plants testing positive in transgene detection analysis were selected and grown to maturity. Monoclonal antibodies against Tat recognized a protein of the expected size. Interestingly, expression of Tat seemed to be toxic to the plant, as in all cases the fruit exhibited underdeveloped reproductive structures and no seeds. Nine groups of 10 pathogen-free BALB/c male mice were primed either orally, intraperitoneally, or intramuscularly with 10 mg of tomato fruit extract derived from transgenic or wild-type plants and with 10 microg of Tat86 recombinant protein. Mice were immunized at days 0, 14, and 28, and given boosters after 15 weeks; sera were drawn 7 days after each booster, and the antibody titer was determined by enzyme-linked immunosorbent assay. All three immunization approaches induced the development of a strong anti-Tat immunological response, which increased over time. Isotype subclass determination showed the presence of mucosal (immunoglobulin A) immunity soon after the beginning of the oral immunization protocol, and the data were confirmed by the presence of anti-Tat antibodies in fecal pellets and in vaginal washes. We also demonstrated that sera from immunized mice inhibited with high efficiency recombinant Tat-dependent transactivation of the HIV-1 long terminal repeat promoter. This neutralization activity might be relevant for the suppression of extracellular Tat activities, which play an important role in HIV disease development.
Collapse
Affiliation(s)
- Yuri Jorge Peña Ramírez
- Departamento de Ingeniería Genética, Cinvestav Campus Guanajuato, Irapuato, Km 9.6 Libramiento norte, Apartado Postal 629, Irapuato, Gto., México 365002
| | | | | | | | | | | | | |
Collapse
|
39
|
Chéné ID, Basyuk E, Lin YL, Triboulet R, Knezevich A, Chable-Bessia C, Mettling C, Baillat V, Reynes J, Corbeau P, Bertrand E, Marcello A, Emiliani S, Kiernan R, Benkirane M. Suv39H1 and HP1gamma are responsible for chromatin-mediated HIV-1 transcriptional silencing and post-integration latency. EMBO J 2007; 26:424-35. [PMID: 17245432 PMCID: PMC1783455 DOI: 10.1038/sj.emboj.7601517] [Citation(s) in RCA: 248] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 11/30/2006] [Indexed: 12/11/2022] Open
Abstract
HIV-1 gene expression is the major determinant regulating the rate of virus replication and, consequently, AIDS progression. Following primary infection, most infected cells produce virus. However, a small population becomes latently infected and constitutes the viral reservoir. This stable viral reservoir seriously challenges the hope of complete viral eradication. Viewed in this context, it is critical to define the molecular mechanisms involved in the establishment of transcriptional latency and the reactivation of viral expression. We show that Suv39H1, HP1gamma and histone H3Lys9 trimethylation play a major role in chromatin-mediated repression of integrated HIV-1 gene expression. Suv39H1, HP1gamma and histone H3Lys9 trimethylation are reversibly associated with HIV-1 in a transcription-dependent manner. Finally, we show in different cellular models, including PBMCs from HIV-1-infected donors, that HIV-1 reactivation could be achieved after HP1gamma RNA interference.
Collapse
Affiliation(s)
- Isaure du Chéné
- Laboratoire de Virologie Moléculaire, Institut de Génétique Humaine, UPR 1142, Montpellier, France
| | - Euguenia Basyuk
- Traffic et Assemblage des RNPs, Institut de Génétique Moléculaire, UMR 5355, Montpellier, France
| | - Yea-Lih Lin
- Lentivirus et Transfert de Gènes, Institut de Génétique Humaine, UPR 1142, Montpellier, France
| | - Robinson Triboulet
- Laboratoire de Virologie Moléculaire, Institut de Génétique Humaine, UPR 1142, Montpellier, France
| | - Anna Knezevich
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Christine Chable-Bessia
- Laboratoire de Virologie Moléculaire, Institut de Génétique Humaine, UPR 1142, Montpellier, France
| | - Clement Mettling
- Lentivirus et Transfert de Gènes, Institut de Génétique Humaine, UPR 1142, Montpellier, France
| | - Vincent Baillat
- Service des Maladies Infectieuses et Tropicales Hôpital Gui de Chauliac, Institut de Génétique Moléculaire, UMR 5355, Montpellier, France
| | - Jacques Reynes
- Service des Maladies Infectieuses et Tropicales Hôpital Gui de Chauliac, Institut de Génétique Moléculaire, UMR 5355, Montpellier, France
| | - Pierre Corbeau
- Lentivirus et Transfert de Gènes, Institut de Génétique Humaine, UPR 1142, Montpellier, France
| | - Edouard Bertrand
- Traffic et Assemblage des RNPs, Institut de Génétique Moléculaire, UMR 5355, Montpellier, France
| | - Alessandro Marcello
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Stephane Emiliani
- Département de Maladies Infectieuses, Institut Cochin, Paris, France
| | - Rosemary Kiernan
- Laboratoire de Virologie Moléculaire, Institut de Génétique Humaine, UPR 1142, Montpellier, France
| | - Monsef Benkirane
- Laboratoire de Virologie Moléculaire, Institut de Génétique Humaine, UPR 1142, Montpellier, France
- Laboratoire de Virologie Moléculaire, Institut de Génétique Humaine, CNRS, UPR 1142, Montpellier, 141 rue la Cardonille, 34396 Montpellier Cedex 5, France. Tel.: +33 4 99 61 99 32; Fax: + 33 4 99 61 99 01; E-mail:
| |
Collapse
|
40
|
Nekhai S, Bhat UG, Ammosova T, Radhakrishnan SK, Jerebtsova M, Niu X, Foster A, Layden TJ, Gartel AL. A novel anticancer agent ARC antagonizes HIV-1 and HCV. Oncogene 2006; 26:3899-903. [PMID: 17173067 DOI: 10.1038/sj.onc.1210158] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) pose major public health concerns worldwide. HCV is clearly associated with the occurrence of hepatocellular carcinoma, and recently HIV infection has also been linked to the development of a multitude of cancers. Previously, we identified a novel nucleoside analog transcriptional inhibitor ARC (4-amino-6-hydrazino-7-beta-D-ribofuranosyl-7H-pyrrolo[2,3-d]-pyrimidine-5-carboxamide) that exhibited proapoptotic and antiangiogenic properties in vitro. Here, we evaluated the effect of ARC on HIV-1 transcription and HCV replication. Using reporter assays, we found that ARC inhibited HIV-1 Tat-based transactivation in different cell systems. Also, using hepatoma cells that harbor subgenomic and full-length replicons of HCV, we found that ARC inhibited HCV replication. Together, our data indicate that ARC could be a promising candidate for the development of antiviral therapeutics against HIV and HCV.
Collapse
Affiliation(s)
- S Nekhai
- Center for Sickle Cell Disease, Howard University College of Medicine, Washington, DC, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Deng G, Qiao W, Su Y, Sha R, Geng Y, Chen Q. Internalization of Jembrana disease virus Tat: Possible pathway and implication. Virus Res 2006; 121:122-33. [PMID: 16870296 DOI: 10.1016/j.virusres.2006.01.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Revised: 01/22/2006] [Accepted: 01/23/2006] [Indexed: 11/21/2022]
Abstract
Jembrana disease virus (JDV) is a lentivirus highly related to the bovine immunodeficiency virus (BIV). It causes an acute disease with high mortality rate within 1-2 weeks. JDV encodes the most potent Tat (JTat) of any of the lentiviruses. JTat can transactivate all LTRs and functionally substitute for HIV Tat in the viral genome and may function as a pivotal regulator in the acute pathogenesis of JDV. The goal of this paper is to study JTat internalization by cells, the mechanisms involved in internalization, and the effect of JTat on neighbouring cells. By quantification and fluorescence microscopy, we found that the internalization of extracellular EGFP-JTat fusion protein was both time and dose-dependent, but endocytosis and energy independent. We identified that arginines which were responsible for the internalization. Internalized JTat was distributed in both the nucleus and the cytoplasm, could transactivate JDV LTR and modulate cellular gene expression. Based on our findings, we propose that secretion and internalization of JTat may be a way for JDV to influence neighbouring cells and make the cellular environment more amenable to viral infection.
Collapse
Affiliation(s)
- Gang Deng
- College of Life Sciences and Tianjin State Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, China
| | | | | | | | | | | |
Collapse
|
42
|
Faller EM, McVey MJ, Kakal JA, MacPherson PA. Interleukin-7 Receptor Expression on CD8 T-Cells Is Downregulated by the HIV Tat Protein. J Acquir Immune Defic Syndr 2006; 43:257-69. [PMID: 16967044 DOI: 10.1097/01.qai.0000230319.78288.f4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have previously shown decreased expression of the interleukin (IL)-7 receptor alpha-chain (CD127) on CD8 T-cells in HIV-infected patients and an apparent recovery of this receptor in those receiving antiretroviral therapy with sustained viral suppression. Here, we demonstrate that the HIV Tat protein specifically downregulates cell surface expression of CD127 on human CD8 T-cells in a dose- and time-dependent manner. The effects of Tat on CD127 expression could be blocked with anti-Tat monoclonal antibodies or by preincubating Tat with heparin. Tat had no effect on the expression of other cell surface proteins examined, including CD132, or on cell viability over 72 hours. Further, CD127 expression was not altered by other HIV proteins, including gp160 or Nef. Preincubation of purified CD8 T-cells with Tat protein inhibited CD8 T-cell proliferation and perforin synthesis after stimulation with IL-7. Because IL-7 signaling is essential for optimal CD8 T-cell proliferation and function, the downregulation of CD127 and apparent inhibition of cytotoxic activity by Tat may play an important role in HIV-induced immune dysregulation and impaired cell-mediated immunity.
Collapse
|
43
|
Abstract
HIV-1 Tat protein is a crucial element for viral replication; therefore, its inhibition might be exploited against the AIDS infection. To gain insights on the natural variability of this protein, we present a comparative investigation on the relationship between the primary sequences and the experimentally available three-dimensional structures from the HIV-1 Tat variants Z2, BRU, and MAL. Our computational tools include sequence conservation algorithms, structural analysis, electrostatic modeling, and molecular dynamics (MD) simulations. We find that two regions located between residues 10-18 and 41-52 display the highest primary sequence conservation, while the most conserved region among the available structures corresponds approximately to the segment between positions approximately 44 and 50. Furthermore, in spite of their large structural divergence, Tat variants share a common mode for long-range intramolecular interactions. Finally, the flexibility of the Z2, BRU, and MAL variants, as emerging from multinanosecond MD simulations, is rather similar. Based on this work, we conclude that the turnlike region between amino acids 44 and 50 is structurally most conserved, emerging as an important motif for pharmaceutical targeting aimed toward inhibiting Tat action.
Collapse
Affiliation(s)
- Sergio Pantano
- International School for Advanced Studies and INFM-DEMOCRITOS Modeling Center for Research in Atomistic Simulation, Trieste, Italy
| | | |
Collapse
|
44
|
Berro R, Kehn K, de la Fuente C, Pumfery A, Adair R, Wade J, Colberg-Poley AM, Hiscott J, Kashanchi F. Acetylated Tat regulates human immunodeficiency virus type 1 splicing through its interaction with the splicing regulator p32. J Virol 2006; 80:3189-204. [PMID: 16537587 PMCID: PMC1440361 DOI: 10.1128/jvi.80.7.3189-3204.2006] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) potent transactivator Tat protein mediates pleiotropic effects on various cell functions. Posttranslational modification of Tat affects its activity during viral transcription. Tat binds to TAR and subsequently becomes acetylated on lysine residues by histone acetyltransferases. Novel protein-protein interaction domains on acetylated Tat are then established, which are necessary for both sustained transcriptional activation of the HIV-1 promoter and viral transcription elongation. In this study, we investigated the identity of proteins that preferentially bound acetylated Tat. Using a proteomic approach, we identified a number of proteins that preferentially bound AcTat, among which p32, a cofactor of splicing factor ASF/SF-2, was identified. We found that p32 was recruited to the HIV-1 genome, suggesting a mechanism by which acetylation of Tat may inhibit HIV-1 splicing needed for the production of full-length transcripts. Using Tat from different clades, harboring a different number of acetylation sites, as well as Tat mutated at lysine residues, we demonstrated that Tat acetylation affected splicing in vivo. Finally, using confocal microscopy, we found that p32 and Tat colocalize in vivo in HIV-1-infected cells.
Collapse
Affiliation(s)
- Reem Berro
- Genetics Program, The George Washington University, Washington, D.C. 20037, Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, D.C. 20037, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada, The Institute for Genomic Research, Rockville, Maryland 20850
| | - Kylene Kehn
- Genetics Program, The George Washington University, Washington, D.C. 20037, Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, D.C. 20037, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada, The Institute for Genomic Research, Rockville, Maryland 20850
| | - Cynthia de la Fuente
- Genetics Program, The George Washington University, Washington, D.C. 20037, Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, D.C. 20037, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada, The Institute for Genomic Research, Rockville, Maryland 20850
| | - Anne Pumfery
- Genetics Program, The George Washington University, Washington, D.C. 20037, Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, D.C. 20037, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada, The Institute for Genomic Research, Rockville, Maryland 20850
| | - Richard Adair
- Genetics Program, The George Washington University, Washington, D.C. 20037, Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, D.C. 20037, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada, The Institute for Genomic Research, Rockville, Maryland 20850
| | - John Wade
- Genetics Program, The George Washington University, Washington, D.C. 20037, Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, D.C. 20037, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada, The Institute for Genomic Research, Rockville, Maryland 20850
| | - Anamaris M. Colberg-Poley
- Genetics Program, The George Washington University, Washington, D.C. 20037, Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, D.C. 20037, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada, The Institute for Genomic Research, Rockville, Maryland 20850
| | - John Hiscott
- Genetics Program, The George Washington University, Washington, D.C. 20037, Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, D.C. 20037, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada, The Institute for Genomic Research, Rockville, Maryland 20850
| | - Fatah Kashanchi
- Genetics Program, The George Washington University, Washington, D.C. 20037, Department of Biochemistry and Molecular Biology, The George Washington University School of Medicine, Washington, D.C. 20037, Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, Washington, D.C. 20010, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada, The Institute for Genomic Research, Rockville, Maryland 20850
- Corresponding author. Mailing address: The George Washington University, 2300 I St., NW, Ross Hall, Room 551, Washington, DC 20037. Phone: (202) 994-1781. Fax: (202) 994-1780. E-mail:
| |
Collapse
|
45
|
Wilson ME, Allred KF, Bisotti AJ, Bruce-Keller A, Chuahan A, Nath A. Estradiol negatively regulates HIV-LTR promoter activity in glial cells. AIDS Res Hum Retroviruses 2006; 22:350-6. [PMID: 16623639 DOI: 10.1089/aid.2006.22.350] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
HIV-associated dementia results from neuronal loss and an alteration of neuronal function due to a loss of synapses. While HIV infection in astrocytes is limited, astrocytes exhibit a chronic nonproductive infection that can lead to the release of neurotoxic proteins. Additionally, infection can disrupt the normal neurotrophic role of astrocytes that results in neuronal death. Gonadal steroid hormones are known to act as trophic and protective factors in the brain under a variety of normal and pathological conditions. In the present study, to determine if estrogen plays a role in the ability of Tat to function as a transcriptional activator within astrocytes, we examined the effect of estrogen on regulation of viral transcription. We utilized an immortalized human astrocyte cell line (SVGA) stably transfected with a reporter plasmid containing the HIV-1IIIB LTR driving the chloramphenicol acetyltransferase (CAT) gene. The amount of transcriptional activity was measured by quantifying the amount of CAT produced. We determined that 17beta-estradiol treatment (1 nM) had no effect on basal LTR activity. Following transfection with a Tat-expressing plasmid, there was a 100-fold increase in CAT production. This induction was reduced by 40% in cells pretreated with 17beta-estradiol. 17beta- Estradiol only suppressed transcription stimulated by Tat. Furthermore, we determined that this effect was specific to 17beta-estradiol and estrogen receptor agonists. This activity was limited to astrocytes as no effect was observed in a monocytic cell line. Finally, the mechanism of action did not involve an alteration in levels of Cdk9 or Cyclin T1 proteins necessary for Tat activation of the HIV-1 LTR. This study demonstrates a novel activity of 17beta-estradiol in glial cells that could play a role in the maintenance of neuronal health during HIV infection of the central nervous system.
Collapse
Affiliation(s)
- Melinda E Wilson
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky 40536, USA.
| | | | | | | | | | | |
Collapse
|
46
|
Pantano S, Marcello A, Ferrari A, Gaudiosi D, Sabò A, Pellegrini V, Beltram F, Giacca M, Carloni P. Insights on HIV-1 Tat:P/CAF bromodomain molecular recognition from in vivo experiments and molecular dynamics simulations. Proteins 2006; 62:1062-73. [PMID: 16362936 DOI: 10.1002/prot.20805] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Structural and functional studies indicate that, through its bromodomain, the cellular acetyltransferase P/CAF binds the acetylated Tat protein of human immunodeficiency virus type 1 (HIV-1) and promotes transcriptional activation of the integrated provirus. Based on the NMR structure of P/CAF complexed with an acetylated Tat peptide, here we use molecular dynamics simulations to construct a model describing the interaction between full length Tat and the P/CAF bromodomain. Our calculations show that the protein-protein interface involves hydrophobic interactions between the P/CAF ZA loop and the Tat core domain. In particular, tyrosines 760 and 761 of P/CAF, two residues that are highly conserved in most known bromodomains, play an essential role for the binding. Fluorescence resonance energy transfer (FRET) experiments performed in this work demonstrate that P/CAF proteins in which these tyrosines are mutated into hydrophilic residues neither bind to Tat inside the cells nor mediate Tat transactivation. The combination of theoretical and in vivo studies provides new insights into the specificity of bromodomain recognition.
Collapse
Affiliation(s)
- Sergio Pantano
- International School for Advanced Studies, INFM-DEMOCRITOS Modeling Center for Research in Atomistic Simulation, Trieste, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Frugier M, Ryckelynck M, Giegé R. tRNA-balanced expression of a eukaryal aminoacyl-tRNA synthetase by an mRNA-mediated pathway. EMBO Rep 2006; 6:860-5. [PMID: 16113655 PMCID: PMC1369159 DOI: 10.1038/sj.embor.7400481] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 06/09/2005] [Accepted: 06/09/2005] [Indexed: 11/09/2022] Open
Abstract
Aminoacylation of transfer RNAs is a key step during translation. It is catalysed by the aminoacyl-tRNA synthetases (aaRSs) and requires the specific recognition of their cognate substrates, one or several tRNAs, ATP and the amino acid. Whereas the control of certain aaRS genes is well known in prokaryotes, little is known about the regulation of eukaryotic aaRS genes. Here, it is shown that expression of AspRS is regulated in yeast by a feedback mechanism that necessitates the binding of AspRS to its messenger RNA. This regulation leads to a synchronized expression of AspRS and tRNA(Asp). The correlation between AspRS expression and mRNA(AspRS) and tRNA(Asp) concentrations, as well as the presence of AspRS in the nucleus, suggests an original regulation mechanism. It is proposed that the surplus of AspRS, not sequestered by tRNA(Asp), is imported into the nucleus where it binds to mRNA(AspRS) and thus inhibits its accumulation.
Collapse
Affiliation(s)
- Magali Frugier
- Département Machineries Traductionnelles, UPR 9002, Institut de Biologie Moléculaire et Cellulaire du CNRS, 15 rue René Descartes, 67084 Strasbourg Cedex, France.
| | | | | |
Collapse
|
48
|
Williams CA, Mondal D, Agrawal KC. The HIV-1 Tat protein enhances megakaryocytic commitment of K562 cells by facilitating CREB transcription factor coactivation by CBP. Exp Biol Med (Maywood) 2006; 230:872-84. [PMID: 16339753 DOI: 10.1177/153537020523001113] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Tat protein regulates transcription factor functions and alters cellular gene expression. Because hematopoietic progenitor cell (HPC) differentiation requires activation of lineage-specific transcription factors, Tat may affect hematopoiesis in HIV-1-infected micro-environments. We have monitored the molecular effects of Tat on megakaryocytic differentiation in the HPC line, K562. Flow cytometry analysis of CD61 indicated that phorbol myristate acetate (PMA) (16 nM) stimulated megakaryocytic commitment of K562 cells was increased (3- to 4-fold) following exposure to Tat (1-100 ng/ml). Activation of the megakaryocytic transcription factor cAMP regulatory element binding protein (CREB) and its coactivation by the CREB binding protein (CBP) was subsequently monitored. CREB phosphorylation and DNA binding were measured by Western immunodetection and electrophoretic mobility shift assays (EMSA), respectively. Within 2 hrs after stimulation, Tat increased both CREB phosphorylation and DNA binding by 7- to 10-fold. Transient cotransfection with CREB reporter and CBP expression plasmids demonstrated that Tat treatment increases (3- to 4-fold) both PMA-stimulated and CBP-mediated transcription via the cAMP regulatory element. Histone acetyl transferase (HAT) activity was increased (8- to 10-fold) in Tat-stimulated cells, which suggested increased chromosomal accessibility of transcription factors. Two-hybrid cotransfection assays using reporter plasmid containing the GAL4 DNA-binding domain and expression plasmid coding for the GAL4-CBP fusion protein, showed that Tat increases (2-fold) CBP-mediated coactivation of CREB. Both reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis showed that Tat treatment increases CBP gene expression (7- to 9-fold) and protein levels (5- to 7-fold) within 6-12 hrs after stimulation. Our findings indicated that Tat treatment increases both CREB function and CREB coactivation by CBP, which may facilitate megakaryocytic commitment of K562 cells. Induction of this molecular signaling by HIV-1 Tat protein may have relevance in understanding the HIV-induced hematologic manifestations and possibly in regulation of viral infectivity parameters in progenitor cell reservoirs.
Collapse
Affiliation(s)
- Christopher A Williams
- Department of Pharmacology, Tulane University Health Sciences Center, New Orleans, LA 70112, USA
| | | | | |
Collapse
|
49
|
Abstract
Eradication of HIV-1 from an infected individual cannot be achieved by current regimens. Viral reservoirs established early during the infection remain unaffected by anti-retroviral therapy for a long time and are able to replenish systemic infection upon interruption of the treatment. Therapeutic targeting of viral latency will require a better understanding of the basic mechanisms underlying the establishment and long-term maintenance of HIV-1 in resting memory CD4 T cells, the most prominent reservoir of transcriptionally silent provirus. Since the molecular mechanisms that permit long term transcriptional control of proviral gene expression in these cells are still obscure, this review aims at summarizing the various aspects of the problem that need to be considered. In particular, this review will focus the attention on the control of transcription imposed by chromatin through various epigenetic mechanisms. Exploring the molecular details of viral latency will provide new insights for eventual future therapeutics that aim at viral eradication.
Collapse
Affiliation(s)
- Alessandro Marcello
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano, 99 - 34012 Trieste, Italy.
| |
Collapse
|
50
|
Dormeyer W, Ott M, Schnölzer M. Analysis of p300 acetyltransferase substrate specificity by MALDI TOF mass spectrometry. Methods 2005; 36:376-82. [PMID: 16085422 DOI: 10.1016/j.ymeth.2005.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/30/2005] [Indexed: 11/19/2022] Open
Abstract
Acetyltransferase enzymes target specific lysine residues in substrate proteins. While the list of histone and nonhistone substrates is growing, the mechanisms of substrate selection remain unclear. Here, we describe a mass spectrometric approach to examine the site selection of the acetyltransferase p300 in the HIV-1 protein Tat. Tat is acetylated by p300 at a single lysine (K50) within its basic RNA-binding domain. To determine the sequence requirements for K50 recognition within this domain, we synthesized mixtures of "degenerated" Tat peptides, in which one of the surrounding residues was substituted by all proteinogenic amino acids. Peptide mixtures were assembled based on nonoverlapping peptide masses and acetylated by p300 in a standard in vitro acetylation reaction. Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identified amino acid substitutions that prevented acetylation by p300. This approach represents a fast and comprehensive screening method that was applied to the six surrounding residues of K50 in Tat. It can be applied to any known acetyltransferase substrate and might help to define consensus recognition sequences for individual acetyltransferase enzymes.
Collapse
Affiliation(s)
- Wilma Dormeyer
- Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | | | | |
Collapse
|