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di Bari I, Franzin R, Picerno A, Stasi A, Cimmarusti MT, Di Chiano M, Curci C, Pontrelli P, Chironna M, Castellano G, Gallone A, Sabbà C, Gesualdo L, Sallustio F. Severe acute respiratory syndrome coronavirus 2 may exploit human transcription factors involved in retinoic acid and interferon-mediated response: a hypothesis supported by an in silico analysis. New Microbes New Infect 2021; 41:100853. [PMID: 33680474 PMCID: PMC7912353 DOI: 10.1016/j.nmni.2021.100853] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/22/2021] [Accepted: 02/24/2021] [Indexed: 02/06/2023] Open
Abstract
The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19), resulting in acute respiratory disease, is a worldwide emergency. Because recently it has been found that SARS-CoV is dependent on host transcription factors (TF) to express the viral genes, efforts are required to understand the molecular interplay between virus and host response. By bioinformatic analysis, we investigated human TF that can bind the SARS-CoV-2 sequence and can be involved in viral transcription. In particular, we analysed the key role of TF involved in interferon (IFN) response. We found that several TF could be induced by the IFN antiviral response, specifically some induced by IFN-stimulated gene factor 3 (ISGF3) and by unphosphorylated ISGF3, which were found to promote the transcription of several viral open reading frame. Moreover, we found 22 TF binding sites present only in the sequence of virus infecting humans but not bat coronavirus RaTG13. The 22 TF are involved in IFN, retinoic acid signalling and regulation of transcription by RNA polymerase II, thus facilitating its own replication cycle. This mechanism, by competition, may steal the human TF involved in these processes, explaining SARS-CoV-2's disruption of IFN-I signalling in host cells and the mechanism of the SARS retinoic acid depletion syndrome leading to the cytokine storm. We identified three TF binding sites present exclusively in the Brazilian SARS-CoV-2 P.1 variant that may explain the higher severity of the respiratory syndrome. These data shed light on SARS-CoV-2 dependence from the host transcription machinery associated with IFN response and strengthen our knowledge of the virus's transcription and replicative activity, thus paving the way for new targets for drug design and therapeutic approaches.
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Affiliation(s)
- I di Bari
- Department of Emergency and Organ Transplantation, University of Bari 'Aldo Moro', Bari, Italy
| | - R Franzin
- Department of Emergency and Organ Transplantation, University of Bari 'Aldo Moro', Bari, Italy
| | - A Picerno
- Department of Emergency and Organ Transplantation, University of Bari 'Aldo Moro', Bari, Italy
| | - A Stasi
- Department of Emergency and Organ Transplantation, University of Bari 'Aldo Moro', Bari, Italy
| | - M T Cimmarusti
- Department of Emergency and Organ Transplantation, University of Bari 'Aldo Moro', Bari, Italy
| | - M Di Chiano
- Department of Emergency and Organ Transplantation, University of Bari 'Aldo Moro', Bari, Italy
| | - C Curci
- Department of Emergency and Organ Transplantation, University of Bari 'Aldo Moro', Bari, Italy.,Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari 'Aldo Moro', Bari, Italy
| | - P Pontrelli
- Department of Emergency and Organ Transplantation, University of Bari 'Aldo Moro', Bari, Italy
| | - M Chironna
- Department of Biomedical Sciences and Human Oncology- Hygiene Section, University of Bari, Bari, Italy
| | - G Castellano
- Department of Medical and Surgical Science, University of Foggia, Foggia, Italy
| | - A Gallone
- Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari 'Aldo Moro', Bari, Italy
| | - C Sabbà
- Department of Interdisciplinary Medicine, University of Bari 'Aldo Moro', Bari, Italy
| | - L Gesualdo
- Department of Emergency and Organ Transplantation, University of Bari 'Aldo Moro', Bari, Italy
| | - F Sallustio
- Department of Interdisciplinary Medicine, University of Bari 'Aldo Moro', Bari, Italy
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Lee Yu K, Jung YM, Park SH, Lee SD, You JC. Human transcription factor YY1 could upregulate the HIV-1 gene expression. BMB Rep 2021. [PMID: 31818358 PMCID: PMC7262509 DOI: 10.5483/bmbrep.2020.53.5.222] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Gene expression in HIV-1 is regulated by the promoters in 5’ long-terminal repeat (LTR) element, which contain multiple DNA regulatory elements that serve as binding sites for cellular transcription factors. YY1 could repress HIV-1 gene expression and latent infection. Here, however, we observed that virus production can be increased by YY1 over-expression and decreased under YY1 depleted condition by siRNA treatment. To identify functional domain(s) of YY1 activation, we constructed a number of YY1 truncated mutants. Our data show that full-length YY1 enhances the viral transcription both through U3 and U3RU5 promoters. Moreover, the C-terminal region (296-414 residues) of YY1 is responsible for the transcriptional upregulation, which could be enhanced further in the presence of the viral Tat protein. The central domain of YY1 (155-295 residues) does not affect LTR activity but has a negative effect on HIV-1 gene expression. Taken together, our study shows that YY1 could act as a transcriptional activator in HIV-1 replication, at least in the early stages of infection.
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Affiliation(s)
- Kyung Lee Yu
- National Research Laboratory of Molecular Virology, Department of Pathology, The Catholic University of Korea, Seoul 63071, Korea
| | - Yu Mi Jung
- National Research Laboratory of Molecular Virology, Department of Pathology, The Catholic University of Korea, Seoul 63071, Korea
| | - Seong Hyun Park
- National Research Laboratory of Molecular Virology, Department of Pathology, The Catholic University of Korea, Seoul 63071, Korea
| | - Seong Deok Lee
- National Research Laboratory of Molecular Virology, Department of Pathology, The Catholic University of Korea, Seoul 63071, Korea
| | - Ji Chang You
- National Research Laboratory of Molecular Virology, Department of Pathology, The Catholic University of Korea, Seoul 63071, Korea
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3
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Li Z, Wang Y, Liu X, Xing X, Zhang Y. Interleukin‐32ε induces caspase‐independent apoptosis mediated by N‐Myc interactor in macrophages infected with
Mycobacterium tuberculosis. FEBS J 2018; 286:572-583. [DOI: 10.1111/febs.14717] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 10/18/2018] [Accepted: 11/30/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Zhongxia Li
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture College of Veterinary Medicine Northwest A&F University Yangling China
| | - Yizhi Wang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture College of Veterinary Medicine Northwest A&F University Yangling China
| | - Xin Liu
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture College of Veterinary Medicine Northwest A&F University Yangling China
| | - Xupeng Xing
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture College of Veterinary Medicine Northwest A&F University Yangling China
| | - Yong Zhang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture College of Veterinary Medicine Northwest A&F University Yangling China
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De Crignis E, Mahmoudi T. HIV eradication: combinatorial approaches to activate latent viruses. Viruses 2014; 6:4581-608. [PMID: 25421889 PMCID: PMC4246239 DOI: 10.3390/v6114581] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 11/01/2014] [Accepted: 11/13/2014] [Indexed: 12/11/2022] Open
Abstract
The concept of eradication of the Human Immune Deficiency Virus (HIV) from infected patients has gained much attention in the last few years. While combination Anti-Retroviral Therapy (c-ART) has been extremely effective in suppressing viral replication, it is not curative. This is due to the presence of a reservoir of latent HIV infected cells, which persist in the presence of c-ART. Recently, pharmaceutical approaches have focused on the development of molecules able to induce HIV-1 replication from latently infected cells in order to render them susceptible to viral cytopathic effects and host immune responses. Alternative pathways and transcription complexes function to regulate the activity of the HIV promoter and might serve as molecular targets for compounds to activate latent HIV. A combined therapy coupling various depressors and activators will likely be the most effective in promoting HIV replication while avoiding pleiotropic effects at the cellular level. Moreover, in light of differences among HIV subtypes and variability in integration sites, the combination of multiple agents targeting multiple pathways will increase likelihood of therapeutic effectiveness and prevent mutational escape. This review provides an overview of the mechanisms that can be targeted to induce HIV activation focusing on potential combinatorial approaches.
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Affiliation(s)
- Elisa De Crignis
- Department of Biochemistry, Erasmus University Medical Center, Rotterdam 3015 CN, The Netherlands.
| | - Tokameh Mahmoudi
- Department of Biochemistry, Erasmus University Medical Center, Rotterdam 3015 CN, The Netherlands.
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5
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Mechanisms of HIV Transcriptional Regulation and Their Contribution to Latency. Mol Biol Int 2012; 2012:614120. [PMID: 22701796 PMCID: PMC3371693 DOI: 10.1155/2012/614120] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 04/09/2012] [Indexed: 12/26/2022] Open
Abstract
Long-lived latent HIV-infected cells lead to the rebound of virus replication following antiretroviral treatment interruption and present a major barrier to eliminating HIV infection. These latent reservoirs, which include quiescent memory T cells and tissue-resident macrophages, represent a subset of cells with decreased or inactive proviral transcription. HIV proviral transcription is regulated at multiple levels including transcription initiation, polymerase recruitment, transcription elongation, and chromatin organization. How these biochemical processes are coordinated and their potential role in repressing HIV transcription along with establishing and maintaining latency are reviewed.
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Santhekadur PK, Rajasekaran D, Siddiq A, Gredler R, Chen D, Schaus SE, Hansen U, Fisher PB, Sarkar D. The transcription factor LSF: a novel oncogene for hepatocellular carcinoma. Am J Cancer Res 2012; 2:269-285. [PMID: 22679558 PMCID: PMC3365805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/05/2012] [Indexed: 06/01/2023] Open
Abstract
The transcription factor LSF (Late SV40 Factor), also known as TFCP2, belongs to the LSF/CP2 family related to Grainyhead family of proteins and is involved in many biological events, including regulation of cellular and viral promoters, cell cycle, DNA synthesis, cell survival and Alzheimer's disease. Our recent studies establish an oncogenic role of LSF in Hepatocellular carcinoma (HCC). LSF overexpression is detected in human HCC cell lines and in more than 90% cases of human HCC patients, compared to normal hepatocytes and liver, and its expression level showed significant correlation with the stages and grades of the disease. Forced overexpression of LSF in less aggressive HCC cells resulted in highly aggressive, angiogenic and multi-organ metastatic tumors in nude mice. Conversely, inhibition of LSF significantly abrogated growth and metastasis of highly aggressive HCC cells in nude mice. Microarray studies revealed that as a transcription factor LSF modulated specific genes regulating invasion, angiogenesis, chemoresistance and senescence. LSF transcriptionally regulates thymidylate synthase (TS) gene, thus contributing to cell cycle regulation and chemoresistance. Our studies identify a network of proteins, including osteopontin (OPN), Matrix metalloproteinase-9 (MMP-9), c-Met and complement factor H (CFH), that are directly regulated by LSF and play important role in LSF-induced hepatocarcinogenesis. A high throughput screening identified small molecule inhibitors of LSF DNA binding and the prototype of these molecules, Factor Quinolinone inhibitor 1 (FQI1), profoundly inhibited cell viability and induced apoptosis in human HCC cells without exerting harmful effects to normal immortal human hepatocytes and primary mouse hepatocytes. In nude mice xenograft studies, FQI1 markedly inhibited growth of human HCC xenografts as well as angiogenesis without exerting any toxicity. These studies establish a key role of LSF in hepatocarcinogenesis and usher in a novel therapeutic avenue for HCC, an invariably fatal disease.
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Affiliation(s)
- Prasanna K Santhekadur
- Department of Human and Molecular Genetics,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
| | - Devaraja Rajasekaran
- Department of Human and Molecular Genetics,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
| | - Ayesha Siddiq
- Department of Human and Molecular Genetics,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
| | - Rachel Gredler
- Department of Human and Molecular Genetics,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
| | - Dong Chen
- Department of Pathology,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
| | - Scott E Schaus
- Department of Chemistry, Center for Chemical Methodology and Library Development at Boston University (CMLDBU)Boston, MA 02215, USA
| | - Ulla Hansen
- Department of Biology, Boston UniversityBoston, MA 02215, USA
| | - Paul B Fisher
- Department of Human and Molecular Genetics,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
- VCU Institute of Molecular Medicine, Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
- VCU Massey Cancer Center,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
| | - Devanand Sarkar
- Department of Human and Molecular Genetics,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
- Department of Pathology,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
- VCU Institute of Molecular Medicine, Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
- VCU Massey Cancer Center,Virginia Commonwealth University, School of MedicineRichmond, VA 23298, USA
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Tschulena U, Sanzenbacher R, Mühlebach MD, Berger A, Münch J, Schindler M, Kirchhoff F, Plesker R, Coulibaly C, Panitz S, Prüfer S, Muckenfuss H, Hamdorf M, Schweizer M, Cichutek K, Flory E. Mutation of a diacidic motif in SIV-PBj Nef impairs T-cell activation and enteropathic disease. Retrovirology 2011; 8:14. [PMID: 21366921 PMCID: PMC3060844 DOI: 10.1186/1742-4690-8-14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 03/02/2011] [Indexed: 11/10/2022] Open
Abstract
Background The non-pathogenic course of SIV infection in its natural host is characterized by robust viral replication in the absence of chronic immune activation and T cell proliferation. In contrast, acutely lethal enteropathic SIVsmm strain PBj induces a strong immune activation and causes a severe acute and lethal disease in pig-tailed macaques after cross-species transmission. One important pathogenicity factor of the PBj virus is the PBj-Nef protein, which contains a conserved diacidic motif and, unusually, an immunoreceptor tyrosine-based activation motif (ITAM). Results Mutation of the diacidic motif in the Nef protein of the SIVsmmPBj abolishes the acute phenotype of this virus. In vitro, wild-type and mutant PBj (PBj-Nef202/203GG) viruses replicated to similar levels in macaque PBMCs, but PBj-Nef202/203GG no longer triggers ERK mitogen-activated protein (MAP) kinase pathway including an alteration of a Nef-associated Raf-1/ERK-2 multiprotein signaling complex. Moreover, stimulation of IL-2 and down-modulation of CD4 and CD28 were impaired in the mutant virus. Pig-tailed macaques infected with PBj-Nef202/203GG did not show enteropathic complications and lethality as observed with wild-type PBj virus, despite efficient replication of both viruses in vivo. Furthermore, PBj-Nef202/203GG infected animals revealed reduced T-cell activation in periphery lymphoid organs and no detectable induction of IL-2 and IL-6. Conclusions In sum, we report here that mutation of the diacidic motif in the PBj-Nef protein abolishes disease progression in pig-tailed macaques despite efficient replication. These data suggest that alterations in the ability of a lentivirus to promote T cell activation and proliferation can have a dramatic impact on its pathogenic potential.
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Affiliation(s)
- Ulrich Tschulena
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany.
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8
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Saxena UH, Owens L, Graham JR, Cooper GM, Hansen U. Prolyl isomerase Pin1 regulates transcription factor LSF (TFCP2) by facilitating dephosphorylation at two serine-proline motifs. J Biol Chem 2010; 285:31139-47. [PMID: 20682773 DOI: 10.1074/jbc.m109.078808] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Transcription factor LSF is essential for cell cycle progression, being required for activating expression of the thymidylate synthase (Tyms) gene at the G1/S transition. We previously established that phosphorylation of LSF in early G1 at Ser-291 and Ser-309 inhibits its transcriptional activity and that dephosphorylation later in G1 is required for its reactivation. Here we reveal the role of prolyl cis-trans isomerase Pin1 in activating LSF, by facilitating dephosphorylation at both Ser-291 and Ser-309. We demonstrate that Pin1 binds LSF both in vitro and in vivo. Using coimmunoprecipitation assays, we identify three SP/TP motifs in LSF (at residues Ser-291, Ser-309, and Thr-329) that are required and sufficient for association with Pin1. Co-expression of Pin1 enhances LSF transactivation potential in reporter assays. The Pin1-dependent enhancement of LSF activity requires residue Thr-329 in LSF, requires both the WW and PPiase domains of Pin1, and correlates with hypophosphorylation of LSF at Ser-291 and Ser-309. These findings support a model in which the binding of Pin1 at the Thr-329-Pro-330 motif in LSF permits isomerization by Pin1 of the peptide bonds at the nearby phosphorylated SP motifs (Ser-291 and Ser-309) to the trans configuration, thereby facilitating their dephosphorylation.
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Affiliation(s)
- Utsav H Saxena
- Department of Biology, Boston University, Boston, Massachusetts 02215, USA
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9
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Hansen U, Owens L, Saxena UH. Transcription factors LSF and E2Fs: tandem cyclists driving G0 to S? Cell Cycle 2009; 8:2146-51. [PMID: 19556876 DOI: 10.4161/cc.8.14.9089] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cell cycle progression in mammalian cells from G(1) into S phase requires sensing and integration of multiple inputs, in order to determine whether to continue to cellular DNA replication and subsequently, to cell division. Passage to S requires transition through the restriction point, which at a molecular level consists of a bistable switch involving E2Fs and pRb family members. At the G(1)/S boundary, a number of genes essential for DNA replication and cell cycle progression are upregulated, promoting entry into S phase. Although the activating E2Fs are the most extensively characterized transcription factors driving G(1)/S expression, LSF is also a transcription factor essential for stimulating G(1)/S gene expression. A critical LSF target gene at this stage, Tyms, encodes thymidylate synthetase. In investigating how LSF is activated in a cell cycle-dependent manner, we recently identified a novel time delay mechanism for regulating its activity during G(1) progression, which is apparently independent of the E2F/pRb axis. This involves inhibition of LSF in early G(1) by two major proliferative signaling pathways: ERK and cyclin C/CDK, followed by gradual dephosphorylation during mid- to late-G(1). Whether LSF and E2F act independently or in concert to promote G(1)/S progression remains to be determined.
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Affiliation(s)
- Ulla Hansen
- Department of Biology and Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA 02215, USA.
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Repetny KJ, Zhong X, Holodick NE, Rothstein TL, Hansen U. Binding of LBP-1a to specific immunoglobulin switch regions in vivo correlates with specific repression of class switch recombination. Eur J Immunol 2009; 39:1387-94. [PMID: 19384868 PMCID: PMC3407417 DOI: 10.1002/eji.200838226] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Upon stimulation of mature B cells, class switch recombination (CSR) can alter the specific immunoglobulin heavy chain constant region that is expressed. In a tissue culture cell line, we previously demonstrated that inhibition of late SV40 factor (LSF) family members enhanced IgM to IgA CSR. Here, isotype specificity of CSR regulation by LSF family members is addressed in primary mouse splenic B cells. First, we demonstrate that leader-binding protein-1a (LBP-1a) is the prevalent family member in B lymphocytes. Second, we demonstrate by ChIP that LBP-1a binds genomic sequences around mouse switch (S) regions in an isotype-specific manner, in accordance with computational predictions: binding is observed to Smu and Salpha, but not to the tested Sgamma1, regions. Importantly, binding of LBP-1a is tightly regulated, with occupancy at genomic S regions dramatically decreasing following LPS stimulation. Finally, the consequence of DNA-binding by LBP-1a is determined using bone marrow chimeric mice in which LSF/LBP-1 activity is inhibited in hematopoietic lineages. Upon in vitro stimulation of such primary B cells, CSR occurs with a higher efficiency to IgA, but not to IgG1. These results are supportive of a model whereby LBP-1a represses CSR in an isotype-specific manner via direct interaction with S regions involved in the recombination.
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Affiliation(s)
| | - Xuemei Zhong
- Department of Medicine, Boston University School of Medicine, Boston MA
| | - Nichol E. Holodick
- Department of Pathology, Boston University School of Medicine, Boston MA
| | | | - Ulla Hansen
- Department of Biology, Boston University, Boston MA
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11
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Phosphorylation by cyclin C/cyclin-dependent kinase 2 following mitogenic stimulation of murine fibroblasts inhibits transcriptional activity of LSF during G1 progression. Mol Cell Biol 2009; 29:2335-45. [PMID: 19237534 DOI: 10.1128/mcb.00687-08] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Transcription factor LSF is required for progression from quiescence through the cell cycle, regulating thymidylate synthase (Tyms) expression at the G(1)/S boundary. Given the constant level of LSF protein from G(0) through S, we investigated whether LSF is regulated by phosphorylation in G(1). In vitro, LSF is phosphorylated by cyclin E/cyclin-dependent kinase 2 (CDK2), cyclin C/CDK2, and cyclin C/CDK3, predominantly on S309. Phosphorylation of LSF on S309 is maximal 1 to 2 h after mitogenic stimulation of quiescent mouse fibroblasts. This phosphorylation is mediated by cyclin C-dependent kinases, as shown by coimmunoprecipitation of LSF and cyclin C in early G(1) and by abrogation of LSF S309 phosphorylation upon suppression of cyclin C with short interfering RNA. Although mouse fibroblasts lack functional CDK3 (the partner of cyclin C in early G(1) in human cells), CDK2 compensates for this absence. By transient transfection assays, phosphorylation at S309, mediated by cyclin C overexpression, inhibits LSF transactivation. Moreover, overexpression of cyclin C and CDK3 inhibits induction of endogenous Tyms expression at the G(1)/S transition. These results identify LSF as only the second known target (in addition to pRb) of cyclin C/CDK activity during progression from quiescence to early G(1). Unexpectedly, this phosphorylation prevents induction of LSF target genes until late G(1).
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Witte V, Laffert B, Gintschel P, Krautkrämer E, Blume K, Fackler OT, Baur AS. Induction of HIV Transcription by Nef Involves Lck Activation and Protein Kinase Cθ Raft Recruitment Leading to Activation of ERK1/2 but Not NFκB. THE JOURNAL OF IMMUNOLOGY 2008; 181:8425-32. [DOI: 10.4049/jimmunol.181.12.8425] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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13
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YY1 and FoxD3 regulate antiretroviral zinc finger protein OTK18 promoter activation induced by HIV-1 infection. J Neuroimmune Pharmacol 2008; 4:103-15. [PMID: 19034670 DOI: 10.1007/s11481-008-9139-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 11/07/2008] [Indexed: 10/21/2022]
Abstract
OTK18 is a C2H2 type zinc finger protein involved in the regulation of HIV-1 replication in human mononuclear phagocytes. Previously, we reported OTK18 expression in brain perivascular macrophages but not in microglia in HIV encephalitis brain. We have cloned the OTK18 promoter region proximal to the transcriptional start site and determined the region responsible (-884/+1) for the basal transcriptional activity in a microglia cell line. Sequential deletion mutation analyses reveal three important response elements: Yingyang-1 (YY1; -805/-777), an HIV-1 response element for promoter activation; FoxD3 (-743/-725), a negative regulatory element; and Ets response element (-725/-707), a basal transcriptional activity response element. HIV-1 infection-induced upregulation of YY1 and c-Ets-1 protein, binding to the promoter region as determined by immunoblotting and chromatin immunoprecipitation and polymerase chain reaction (PCR) assays, and induction of YY1 was also observed in virus-infected monocyte-derived macrophages. Silencing of FoxD3 and YY1 in the cell line by small interfering RNA duplexes specific to these molecules significantly up- and downregulated basal OTK18 promoter activity in FoxD3 and YY1 response element-dependent manners, respectively. On the other hand, infection of primary cultured human microglia significantly reduced YY1 expression and induced FoxD3 as determined by immunoblotting and reverse transcription real-time PCR. These data suggest that HIV-1 induces OTK18 expression through a YY1-mediated manner in human macrophages, although its gene expression is suppressed by FoxD3 upregulation and YY1 downregulation in human microglia. This mechanism may explain the perivascular macrophage-specific expression of OTK18 in HIV encephalitis brains.
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Choudhary SK, Archin NM, Margolis DM. Hexamethylbisacetamide and disruption of human immunodeficiency virus type 1 latency in CD4(+) T cells. J Infect Dis 2008; 197:1162-70. [PMID: 18419522 DOI: 10.1086/529525] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Novel therapeutic approaches are needed to attack persistent proviral human immunodeficiency type 1 (HIV-1) infection. Hexamethylbisacetamide (HMBA), a hybrid bipolar compound, induces expression of the HIV-1 promoter in the long terminal repeat (LTR) region in a Tat-independent manner but mimics the effect of Tat, overcoming barriers to LTR expression and increasing the processivity of LTR transcription complexes. METHODS We studied alterations in cellular factors and their LTR occupancy induced by HMBA in models of latent HIV-1 infection. We measured the induction of viral outgrowth by HMBA in resting CD4(+) T cells from aviremic HIV-1-infected donors. RESULTS HMBA induced outgrowth of HIV-1 from resting CD4(+) T cells recovered from aviremic patients treated with antiretroviral therapy (ART). HMBA triggered cyclin-dependent kinase 9 (CDK9) recruitment to the LTR, a key factor in the induction of efficient HIV-1 expression, via an unexpected interaction with the transcription factor Sp1. The availability of Sp1 and Sp1 DNA binding sites were necessary for HMBA-induced CDK9 recruitment and LTR expression. HMBA signaling via both protein kinase C mu and phosphatidylinositol 3-kinase appeared to contribute to LTR induction. CONCLUSIONS The novel mechanism through which HMBA disrupts latent HIV-1 infection involves 2 cellular kinases that may be therapeutically exploited to induce expression of persistent proviral HIV-1.
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Affiliation(s)
- Shailesh K Choudhary
- Departments of Medicine, University of North Carolina at Chapel Hill 27599-7435, USA
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15
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Klatt A, Zhang Z, Kalantari P, Hankey PA, Gilmour DS, Henderson AJ. The receptor tyrosine kinase RON represses HIV-1 transcription by targeting RNA polymerase II processivity. THE JOURNAL OF IMMUNOLOGY 2008; 180:1670-7. [PMID: 18209063 DOI: 10.4049/jimmunol.180.3.1670] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Efficient HIV-1 transcription requires the induction of cellular transcription factors, such as NF-kappaB, and the viral factor Tat, which through the recruitment of P-TEFb enhances processive transcription. However, whether cellular signals repress HIV-1 transcription to establish proviral latency has not been well studied. Previously, it has been shown that the receptor tyrosine kinase RON inhibits HIV transcription. To gain insights into the biochemical mechanisms by which RON inhibits transcription we examined the binding of transcription factors to the HIV provirus long terminal repeat using chromatin immunoprecipitation. RON expression decreased basal levels of NF-kappaB and RNA polymerase II (Pol II) binding to the HIV provirus long terminal repeat but did not prevent the induction of these complexes following treatment with cytokines. However, RON did decrease efficient transcription elongation because reduced RNA Pol II was associated with HIV-1 genomic sequences downstream of the transcriptional start site. There was a correlation between RON expression and increased binding of factors that negatively regulate transcription elongation, NELF, Spt5, and Pcf11. Furthermore, the ability of RON to inhibit HIV-1 transcription was sensitive to a histone deacetylase inhibitor and was associated with nucleosome remodeling. These results indicate that RON represses HIV transcription at multiple transcriptional check points including initiation, elongation and chromatin organization and are the first studies to show that cellular signaling pathways target Pol II pausing to repress gene expression.
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Affiliation(s)
- Alicia Klatt
- Center of Molecular Immunology and Infectious Diseases, Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA 16802, USA
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Malcolm T, Chen J, Chang C, Sadowski I. Induction of chromosomally integrated HIV-1 LTR requires RBF-2 (USF/TFII-I) and Ras/MAPK signaling. Virus Genes 2007; 35:215-23. [PMID: 17546494 DOI: 10.1007/s11262-007-0109-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 04/30/2007] [Indexed: 10/23/2022]
Abstract
The HIV-1 LTR is regulated by multiple signaling pathways responsive to T cell activation. In this study, we have examined the contribution of the MAPK, calcineurin-NFAT and TNFalpha-NF-kappaB pathways on induction of chromosomally integrated HIV-1 LTR reporter genes. We find that induction by T-cell receptor (CD3) cross-linking and PMA is completely dependent upon a binding site for RBF-2 (USF1/2-TFII-I), known as RBEIII at -120. The MAPK pathway is essential for induction of the wild type LTR by these treatments, as the MEK inhibitors PD98059 and U0126 block induction by both PMA treatment and CD3 cross-linking. Stimulation of cells with ionomycin on its own has no effect on the integrated LTR, indicating that calcineurin-NFAT is incapable of causing induction in the absence of additional signals, but stimulation with both PMA and ionomycin produces a synergistic response. In contrast, stimulation of NF-kappaB by treatment with TNFalpha causes induction of both the wild type and RBEIII mutant LTRs, an effect that is independent of MAPK signaling. USF1, USF2 and TFII-I from unstimulated cells are capable of binding RBEIII in vitro, and furthermore can be observed on the LTR in vivo by chromatin imunoprecipitation from untreated cells. DNA binding activity of USF1/2 is marginally stimulated by PMA/ ionomycin treatment, and all three factors appear to remain associated with the LTR throughout the course of induction. These results implicate major roles for the MAPK pathway and RBF-2 (USF1/2-TFII-I) in coordinating events necessary for transition of latent integrated HIV-1 to active transcription in response to T cell signaling.
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Affiliation(s)
- Tom Malcolm
- Department of Biochemistry and Molecular Biology, Molecular Epigenetics, LSI, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
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Wang CC, Chen JJW, Yang PC. Multifunctional transcription factor YY1: a therapeutic target in human cancer? Expert Opin Ther Targets 2006; 10:253-66. [PMID: 16548774 DOI: 10.1517/14728222.10.2.253] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The multifunctional transcription factor Yin Yang 1 (YY1) is a complex protein that has been shown to play pivotal roles in development, differentiation, cellular proliferation and apoptosis. It can act as a transcriptional repressor, an activator, or an initiator element binding protein that directs and initiates transcription of numerous cellular and viral genes. Because the expression and function of YY1 are known to be intimately associated with cell-cycle progression, the physiological significance of YY1 activity has recently been applied to models of cancer biology. Several lines of evidence imply that YY1 expression and/or activation is associated with tumourigenesis, in addition to its regulatory roles in normal biological processes. However, controversial results also raised and indicated that further studies are still needed to piece all of the seemingly contradictory data into a complete picture. On the basis of YY1 regulations and functions, novel drugs and specific treatment strategies may be developed with new therapeutic applications for tumour patients in the future.
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Affiliation(s)
- Chi-Chung Wang
- National Taiwan University College of Medicine, NTU Center for Genomic Medicine, Taipei, Taiwan, Republic of China
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Stevens M, De Clercq E, Balzarini J. The regulation of HIV-1 transcription: molecular targets for chemotherapeutic intervention. Med Res Rev 2006; 26:595-625. [PMID: 16838299 PMCID: PMC7168390 DOI: 10.1002/med.20081] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The regulation of transcription of the human immunodeficiency virus (HIV) is a complex event that requires the cooperative action of both viral and cellular components. In latently infected resting CD4(+) T cells HIV-1 transcription seems to be repressed by deacetylation events mediated by histone deacetylases (HDACs). Upon reactivation of HIV-1 from latency, HDACs are displaced in response to the recruitment of histone acetyltransferases (HATs) by NF-kappaB or the viral transcriptional activator Tat and result in multiple acetylation events. Following chromatin remodeling of the viral promoter region, transcription is initiated and leads to the formation of the TAR element. The complex of Tat with p-TEFb then binds the loop structures of TAR RNA thereby positioning CDK9 to phosphorylate the cellular RNA polymerase II. The Tat-TAR-dependent phosphorylation of RNA polymerase II plays an important role in transcriptional elongation as well as in other post-transcriptional events. As such, targeting of Tat protein (and/or cellular cofactors) provide an interesting perspective for therapeutic intervention in the HIV replicative cycle and may afford lifetime control of the HIV infection.
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Affiliation(s)
- Miguel Stevens
- Rega Institute for Medical Research, Minderbroedersstraat 10, B‐3000 Leuven, Belgium
| | - Erik De Clercq
- Rega Institute for Medical Research, Minderbroedersstraat 10, B‐3000 Leuven, Belgium
| | - Jan Balzarini
- Rega Institute for Medical Research, Minderbroedersstraat 10, B‐3000 Leuven, Belgium
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Abstract
Hijacking of the host cell’s signal transduction machinery has been increasingly regarded as an important strategy for facilitating virus propagation. The positive-transcription elongation factor (P-TEFb) complex, cyclin-dependent kinase (CDK)9/cyclin T1, is an example of such an attack by HIV. Upon infection of cells, the HIV protein transactivator of transcription (Tat) forms a highly specific complex with the two host cell proteins CDK9 and cyclin T1. This complex ensures phosphorylation of the native CDK9 substrate, RNA polymerase II, leading to productive elongation of viral RNA in the host cell. Although challenging, inhibition of CDK9 activity with small molecules is a therapeutically valid strategy to inhibit HIV replication. Other than direct antiviral agents, that inhibit HIV replication through a direct interaction with viral proteins, CDK9 inhibitors might not suffer from the emergence of resistant virus strains. This review outlines the advantages and prospects of selective CDK9 inhibitors in the management of HIV infections.
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Affiliation(s)
- Bert M Klebl
- GPC Biotech AG, Fraunhoferstr. 20, D-82152 Martinsried, Germany
| | - Axel Choidas
- GPC Biotech AG, Fraunhoferstr. 20, D-82152 Martinsried, Germany
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