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Chen R, Han X, Xu H, Xu J, Cao T, Shan Y, He F, Fang W, Li X. N-terminal domain of classical swine fever virus N pro induces proteasomal degradation of specificity protein 1 with reduced HDAC1 expression to evade from innate immune responses. J Virol 2023; 97:e0111523. [PMID: 37796122 PMCID: PMC10617410 DOI: 10.1128/jvi.01115-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 08/25/2023] [Indexed: 10/06/2023] Open
Abstract
IMPORTANCE Of the flaviviruses, only CSFV and bovine viral diarrhea virus express Npro as the non-structural protein which is not essential for viral replication but functions to dampen host innate immunity. We have deciphered a novel mechanism with which CSFV uses to evade the host antiviral immunity by the N-terminal domain of its Npro to facilitate proteasomal degradation of Sp1 with subsequent reduction of HDAC1 and ISG15 expression. This is distinct from earlier findings involving Npro-mediated IRF3 degradation via the C-terminal domain. This study provides insights for further studies on how HDAC1 plays its role in antiviral immunity, and if and how other viral proteins, such as the core protein of CSFV, the nucleocapsid protein of porcine epidemic diarrhea virus, or even other coronaviruses, exert antiviral immune responses via the Sp1-HDAC1 axis. Such research may lead to a deeper understanding of viral immune evasion strategies as part of their pathogenetic mechanisms.
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Affiliation(s)
- Rong Chen
- Zhejiang University Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China
| | - Xiao Han
- Zhejiang University Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China
| | - Hankun Xu
- Zhejiang University Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China
| | - Jidong Xu
- Zhejiang University Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China
| | - Tong Cao
- Zhejiang University Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China
| | - Ying Shan
- Zhejiang University Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China
| | - Fang He
- Zhejiang University Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China
| | - Weihuan Fang
- Zhejiang University Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China
| | - Xiaoliang Li
- Zhejiang University Institute of Preventive Veterinary Medicine & Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China
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Iyer K, Mitra A, Mitra D. Identification of 5' upstream sequence involved in HSPBP1 gene transcription and its downregulation during HIV-1 infection. Virus Res 2023; 324:199034. [PMID: 36581045 DOI: 10.1016/j.virusres.2022.199034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 12/14/2022] [Accepted: 12/25/2022] [Indexed: 12/27/2022]
Abstract
The Human Immunodeficiency Virus-1 (HIV-1) is known to modulate the host environment for successful replication and propagation like other viruses. The virus utilises its proteins to interact with or modulate host factors and host signalling pathways that may otherwise restrict the virus. A previous study from our lab has shown that the host heat shock protein 70 (HSP70) binding protein (HSPBP1) is a co-chaperone that inhibits viral replication. We have also shown that the virus downregulates HSPBP1 during infection. However, the mechanism of downregulation remains to be elucidated. In the present study, we hypothesized that the HSPBP1 promoter may be repressed during infection leading to its downmodulation at the RNA and protein levels. The 5' upstream region of the HSPBP1 gene was first mapped and it was identified that a fragment comprising of a ∼600 bp upstream region of the transcription start site show the highest promoter-like activity. Further, the Sp1 transcription factor was shown to be essential for normal promoter activation. Our results further demonstrate that HIV-1 downregulates the activity of the identified promoter. It was seen that the viral transactivator protein, Tat, was responsible for the downmodulation of the HSPBP1 promoter. HIV-1 Tat is known to bind and regulate several cellular promoters during infection, thereby making the environment conducive for establishment of the virus. Our results further show that Tat is recruited to the HSPBP1 promoter and in the presence of Tat, recruitment of Sp1 on HSPBP1 promoter was decreased, which explains the suppression of HSPBP1 during HIV-1 infection. Therefore, this study further adds to the list of cellular promoters that are modulated by Tat during HIV-1 infection either directly or indirectly.
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Affiliation(s)
- Kruthika Iyer
- National Centre for Cell Science, NCCS Complex, Savitribai Phule Pune University Campus, Ganeshkhind, Pune, Maharashtra 411007, India
| | - Alapani Mitra
- National Centre for Cell Science, NCCS Complex, Savitribai Phule Pune University Campus, Ganeshkhind, Pune, Maharashtra 411007, India
| | - Debashis Mitra
- National Centre for Cell Science, NCCS Complex, Savitribai Phule Pune University Campus, Ganeshkhind, Pune, Maharashtra 411007, India.
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McAllister JJ, Dahiya S, Berman R, Collins M, Nonnemacher MR, Burdo TH, Wigdahl B. Altered recruitment of Sp isoforms to HIV-1 long terminal repeat between differentiated monoblastic cell lines and primary monocyte-derived macrophages. FRONTIERS IN VIROLOGY 2022. [DOI: 10.3389/fviro.2022.971293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) transcription in cells of the monocyte-macrophage lineage is regulated by interactions between the HIV-1 long terminal repeat (LTR) and a variety of host cell and viral proteins. Binding of the Sp family of transcription factors (TFs) to the G/C box array of the LTR governs both basal as well as activated LTR-directed transcriptional activity. The effect of monocytic differentiation on Sp factor binding and transactivation was examined with respect to the HIV-1 LTR. The binding of Sp1, full-length Sp3 and truncated Sp3 to a high affinity HIV-1 Sp element was specifically investigated and results showed that Sp1 binding increased relative to the binding of the sum of full-length and truncated Sp3 binding following chemically-induced monocytic differentiation in monoblastic (U-937, THP-1) and myelomonocytic (HL-60) cells. In addition, Sp binding ratios from PMA-induced cell lines were shown to more closely approximate those derived from primary monocyte-derived macrophages (MDMs) than did ratios derived from uninduced cell lines. The altered Sp binding phenotype associated with changes in the transcriptional activation mediated by the HIV-1 G/C box array. Additionally, analysis of post-translational modifications on Sp1 and Sp3 revealed a loss of phosphorylation on serine and threonine residues with chemically-induced differentiation indicating that the activity of Sp factors is additionally regulated at the level of post-translational modifications (PTMs).
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Salifou K, Burnard C, Basavarajaiah P, Grasso G, Helsmoortel M, Mac V, Depierre D, Franckhauser C, Beyne E, Contreras X, Dejardin J, Rouquier S, Cuvier O, Kiernan R. Chromatin-associated MRN complex protects highly transcribing genes from genomic instability. SCIENCE ADVANCES 2021; 7:7/21/eabb2947. [PMID: 34020942 PMCID: PMC8139584 DOI: 10.1126/sciadv.abb2947] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 03/31/2021] [Indexed: 05/05/2023]
Abstract
MRN-MDC1 plays a central role in the DNA damage response (DDR) and repair. Using proteomics of isolated chromatin fragments, we identified DDR factors, such as MDC1, among those highly associating with a genomic locus upon transcriptional activation. Purification of MDC1 in the absence of exogenous DNA damage revealed interactions with factors involved in gene expression and RNA processing, in addition to DDR factors. ChIP-seq showed that MRN subunits, MRE11 and NBS1, colocalized throughout the genome, notably at TSSs and bodies of actively transcribing genes, which was dependent on the RNAPII transcriptional complex rather than transcription per se. Depletion of MRN increased RNAPII abundance at MRE11/NBS1-bound genes. Prolonged MRE11 or NBS1 depletion induced single-nucleotide polymorphisms across actively transcribing MRN target genes. These data suggest that association of MRN with the transcriptional machinery constitutively scans active genes for transcription-induced DNA damage to preserve the integrity of the coding genome.
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Affiliation(s)
- Kader Salifou
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
| | - Callum Burnard
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
- Center of Integrative Biology (CBI) CNRS/Université de Toulouse (UMR 5077), 31000, France
| | - Poornima Basavarajaiah
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
| | - Giuseppa Grasso
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
| | - Marion Helsmoortel
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
| | - Victor Mac
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
| | - David Depierre
- Center of Integrative Biology (CBI) CNRS/Université de Toulouse (UMR 5077), 31000, France
| | - Céline Franckhauser
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
| | - Emmanuelle Beyne
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
| | - Xavier Contreras
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
| | - Jérôme Dejardin
- CNRS-UMR 9002, IGH/University of Montpellier, Biology of Repeated Sequences Lab, 34396, France
| | - Sylvie Rouquier
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France
| | - Olivier Cuvier
- Center of Integrative Biology (CBI) CNRS/Université de Toulouse (UMR 5077), 31000, France
| | - Rosemary Kiernan
- CNRS-UMR 9002, Institute of Human Genetics (IGH)/University of Montpellier, Gene Regulation Lab, 34396, France.
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Anisenko A, Kan M, Shadrina O, Brattseva A, Gottikh M. Phosphorylation Targets of DNA-PK and Their Role in HIV-1 Replication. Cells 2020; 9:E1907. [PMID: 32824372 PMCID: PMC7464883 DOI: 10.3390/cells9081907] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 08/13/2020] [Accepted: 08/14/2020] [Indexed: 02/07/2023] Open
Abstract
The DNA dependent protein kinase (DNA-PK) is a trimeric nuclear complex consisting of a large protein kinase and the Ku heterodimer. The kinase activity of DNA-PK is required for efficient repair of DNA double-strand breaks (DSB) by non-homologous end joining (NHEJ). We also showed that the kinase activity of DNA-PK is essential for post-integrational DNA repair in the case of HIV-1 infection. Besides, DNA-PK is known to participate in such cellular processes as protection of mammalian telomeres, transcription, and some others where the need for its phosphorylating activity is not clearly elucidated. We carried out a systematic search and analysis of DNA-PK targets described in the literature and identified 67 unique DNA-PK targets phosphorylated in response to various in vitro and/or in vivo stimuli. A functional enrichment analysis of DNA-PK targets and determination of protein-protein associations among them were performed. For 27 proteins from these 67 DNA-PK targets, their participation in the HIV-1 life cycle was demonstrated. This information may be useful for studying the functioning of DNA-PK in various cellular processes, as well as in various stages of HIV-1 replication.
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Affiliation(s)
- Andrey Anisenko
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (O.S.); (M.G.)
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Marina Kan
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Olga Shadrina
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (O.S.); (M.G.)
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Anna Brattseva
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Marina Gottikh
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (O.S.); (M.G.)
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Roebuck KA, Saifuddin M. Regulation of HIV-1 transcription. Gene Expr 2018; 8:67-84. [PMID: 10551796 PMCID: PMC6157391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Human immunodeficiency virus type-1 (HIV-1) is a highly pathogenic lentivirus that requires transcription of its provirus genome for completion of the viral life cycle and the production of progeny virions. Since the first genetic analysis of HIV-1 in 1985, much has been learned about the transcriptional regulation of the HIV-1 genome in infected cells. It has been demonstrated that HIV-1 transcription depends on a varied and complex interaction of host cell transcription factors with the viral long terminal repeat (LTR) promoter. The regulatory elements within the LTR interact with constitutive and inducible transcription factors to direct the assembly of a stable transcription complex that stimulates multiple rounds of transcription by RNA polymerase II (RNAPII). However, the majority of these transcripts terminate prematurely in the absence of the virally encoded trans-activator protein Tat, which stimulates HIV-1 transcription elongation by interacting with a stem-loop RNA element (TAR) formed at the extreme 5' end of all viral transcripts. The Tat-TAR interaction recruits a cellular kinase into the initiation-elongation complex that alters the elongation properties of RNAPII during its transit through TAR. This review summarizes our current knowledge and understanding of the regulation of HIV-1 transcription in infected cells and highlights the important contributions human lentivirus gene regulation has made to our general understanding of the transcription process.
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Affiliation(s)
- K A Roebuck
- Department of Immunology/Microbiology, Rush Presbyterian St. Luke's Medical Center, Chicago, IL 60612, USA.
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7
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Chen L, Keppler OT, Schölz C. Post-translational Modification-Based Regulation of HIV Replication. Front Microbiol 2018; 9:2131. [PMID: 30254620 PMCID: PMC6141784 DOI: 10.3389/fmicb.2018.02131] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/20/2018] [Indexed: 12/13/2022] Open
Abstract
Human immunodeficiency virus (HIV) relies heavily on the host cellular machinery for production of viral progeny. To exploit cellular proteins for replication and to overcome host factors with antiviral activity, HIV has evolved a set of regulatory and accessory proteins to shape an optimized environment for its replication and to facilitate evasion from the immune system. Several cellular pathways are hijacked by the virus to modulate critical steps during the viral life cycle. Thereby, post-translational modifications (PTMs) of viral and cellular proteins gain increasingly attention as modifying enzymes regulate virtually every step of the viral replication cycle. This review summarizes the current knowledge of HIV-host interactions influenced by PTMs with a special focus on acetylation, ubiquitination, and phosphorylation of proteins linked to cellular signaling and viral replication. Insights into these interactions are surmised to aid development of new intervention strategies.
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Affiliation(s)
- Lin Chen
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Oliver T Keppler
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Christian Schölz
- Max von Pettenkofer-Institute and Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
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8
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Vicenzi E, Poli G. The interferon-stimulated gene TRIM22: A double-edged sword in HIV-1 infection. Cytokine Growth Factor Rev 2018; 40:40-47. [PMID: 29650252 DOI: 10.1016/j.cytogfr.2018.02.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 02/07/2018] [Indexed: 12/17/2022]
Abstract
Infection of target cells by the human immunodeficiency virus type-1 (HIV-1) is hampered by constitutively expressed host cell proteins preventing or curtailing virus replication and therefore defined as "restriction factors". Among them, members of the tripartite motif (TRIM) family have emerged as important players endowed with both antiviral effects and modulatory capacity of the innate immune response. TRIM5α and TRIM19 (i.e. promyelocytic leukemia, PML) are among the best-characterized family members; however, in this review we will focus on the potential role of another family member, i.e. TRIM22, a factor strongly induced by interferon stimulation, in HIV infection in vivo and in vitro in the context of its broader antiviral effects. We will also focus on the potential role of TRIM22 in HIV-1-infected individuals speculating on its dual role in controlling virus replication and more complex role in chronic infection. At the molecular levels, we will review the evidence in favor of a relevant role of TRIM22 as epigenetic inhibitor of HIV-1 transcription acting by preventing the binding of the host cell transcription factor Sp1 to the viral promoter. These evidences suggest that TRIM22 should be considered a potential new player in either the establishment or maintenance of HIV-1 reservoirs of latently infected cells unaffected by combination antiretroviral therapy.
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Affiliation(s)
- Elisa Vicenzi
- Viral Pathogens and Biosafety Unit, P2-P3 Laboratories, DIBIT, Via Olgettina n. 58, 20132, Milano, Italy.
| | - Guido Poli
- AIDS Immunopathogenesis Unit, San Raffaele Scientific Institute, Milan, Italy; Vita-Salute San Raffaele University, School of Medicine, Milan, Italy
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Abstract
Despite the success of cART, greater than 50% of HIV infected people develop cognitive and motor deficits termed HIV-associated neurocognitive disorders (HAND). Macrophages are the major cell type infected in the CNS. Unlike for T cells, the virus does not kill macrophages and these long-lived cells may become HIV reservoirs in the brain. They produce cytokines/chemokines and viral proteins that promote inflammation and neuronal damage, playing a key role in HIV neuropathogenesis. HIV Tat is the transactivator of transcription that is essential for replication and transcriptional regulation of the virus and is the first protein to be produced after HIV infection. Even with successful cART, Tat is produced by infected cells. In this study we examined the role of the HIV Tat protein in the regulation of gene expression in human macrophages. Using THP-1 cells, a human monocyte/macrophage cell line, and their infection with lentivirus, we generated stable cell lines that express Tat-Flag. We performed ChIP-seq analysis of these cells and found 66 association sites of Tat in promoter or coding regions. Among these are C5, CRLF2/TSLPR, BDNF, and APBA1/Mint1, genes associated with inflammation/damage. We confirmed the association of Tat with these sequences by ChIP assay and expression of these genes in our THP-1 cell lines by qRT-PCR. We found that HIV Tat increased expression of C5, APBA1, and BDNF, and decreased CRLF2. The K50A Tat-mutation dysregulated expression of these genes without affecting the binding of the Tat complex to their gene sequences. Our data suggest that HIV Tat, produced by macrophage HIV reservoirs in the brain despite successful cART, contributes to neuropathogenesis in HIV-infected people.
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Maubert ME, Wigdahl B, Nonnemacher MR. Opinion: Inhibition of Blood-Brain Barrier Repair as a Mechanism in HIV-1 Disease. Front Neurosci 2017; 11:228. [PMID: 28491017 PMCID: PMC5405129 DOI: 10.3389/fnins.2017.00228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 04/05/2017] [Indexed: 12/22/2022] Open
Affiliation(s)
- Monique E Maubert
- Department of Microbiology and Immunology, and Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of MedicinePhiladelphia, PA, USA
| | - Brian Wigdahl
- Department of Microbiology and Immunology, and Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of MedicinePhiladelphia, PA, USA.,Sidney Kimmel Cancer Center, Thomas Jefferson UniversityPhiladelphia, PA, USA
| | - Michael R Nonnemacher
- Department of Microbiology and Immunology, and Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of MedicinePhiladelphia, PA, USA
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Chekuri A, Bhaskar C, Bollimpelli VS, Kondapi AK. TopoisomeraseIIβ in HIV-1 transactivation. Arch Biochem Biophys 2016; 593:90-7. [DOI: 10.1016/j.abb.2016.02.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 12/15/2022]
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Cieślik M, Bekiranov S. Genome-wide predictors of NF-κB recruitment and transcriptional activity. BioData Min 2015; 8:37. [PMID: 26617673 PMCID: PMC4661973 DOI: 10.1186/s13040-015-0071-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 11/18/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Inducible transcription factors (TFs) mediate transcriptional responses to environmental cues. In response to multiple inflammatory signals active NF-κB dimers enter the nucleus and trigger cell-type-, and stimulus-specific transcriptional programs. Although much is known about NF-κB inducing pathways and about locus-specific mechanisms of transcriptional control, it is poorly understood how the pre-existing chromatin landscape determines NF-κB target selection and activation. Specifically, it is not known which epigenetic marks and pre-bound TFs serve genome-wide as positive (negative) cues for active NF-κB. RESULTS We applied multivariate and combinatorial data mining techniques on a comprehensive dataset of DNA methylation, DNase I hypersensitivity, eight epigenetic marks, and 34 TFs to arrive at genome-wide patterns that predict NF-κB binding. Strikingly, we observed NF-κB recruitment to accessible and nucleosome-bound sites. Within nucleosomal DNA NF-κB binding was primed by H3K4me1 and H2A.Z, but also hyper-methylated DNA outside of promoters and CpG-islands. Many of these predictors showed combinatorial cooperativity and statistically significant interactions. Recruitment to pre-accessible sites was more frequent and influenced by chromatin-associated TFs. We observed that specific TF-combinations are greatly enriched for (or depleted of) NF-κB binding events. CONCLUSIONS We provide evidence of NF-κB binding within genomic regions that lack classical marks of activity. These pioneer binding events are relatively often associated with transcriptional regulation. Further, our predictive models indicate that specific combinations of epigenetic marks and transcription factors predetermine the NF-κB cistrome, supporting the feasibility of using statistical approaches to identify "histone codes".
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Affiliation(s)
- Marcin Cieślik
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia USA
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48109 USA
| | - Stefan Bekiranov
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia USA
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Measles Virus Infection Inactivates Cellular Protein Phosphatase 5 with Consequent Suppression of Sp1 and c-Myc Activities. J Virol 2015; 89:9709-18. [PMID: 26157124 DOI: 10.1128/jvi.00825-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 07/02/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Measles virus (MeV) causes several unique syndromes, including transient immunosuppression. To clarify the cellular responses to MeV infection, we previously analyzed a MeV-infected epithelial cell line and a lymphoid cell line by microarray and showed that the expression of numerous genes was up- or downregulated in the epithelial cells. In particular, there was a characteristic comprehensive downregulation of housekeeping genes during late stage infection. To identify the mechanism underlying this phenomenon, we examined the phosphorylation status of transcription factors and kinase/phosphatase activities in epithelial cells after infection. MeV infection inactivated cellular protein phosphatase 5 (PP5) that consequently inactivated DNA-dependent protein kinase, which reduced Sp1 phosphorylation levels, and c-Myc degradation, both of which downregulated the expression of many housekeeping genes. In addition, intracellular accumulation of viral nucleocapsid inactivated PP5 and subsequent downstream responses. These findings demonstrate a novel strategy of MeV during infection, which causes the collapse of host cellular functions. IMPORTANCE Measles virus (MeV) is one of the most important pathogens in humans. We previously showed that MeV infection induces the comprehensive downregulation of housekeeping genes in epithelial cells. By examining this phenomenon, we clarified the molecular mechanism underlying the constitutive expression of housekeeping genes in cells, which is maintained by cellular protein phosphatase 5 (PP5) and DNA-dependent protein kinase. We also demonstrated that MeV targets PP5 for downregulation in epithelial cells. This is the first report to show how MeV infection triggers a reduction in overall cellular functions of infected host cells. Our findings will help uncover unique pathogenicities caused by MeV.
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Abstract
Antiretroviral therapy (ART) inhibits HIV-1 replication, but the virus persists in latently infected resting memory CD4+ T cells susceptible to viral reactivation. The virus-encoded early gene product Tat activates transcription of the viral genome and promotes exponential viral production. Here we show that the Tat inhibitor didehydro-cortistatin A (dCA), unlike other antiretrovirals, reduces residual levels of viral transcription in several models of HIV latency, breaks the Tat-mediated transcriptional feedback loop, and establishes a nearly permanent state of latency, which greatly diminishes the capacity for virus reactivation. Importantly, treatment with dCA induces inactivation of viral transcription even after its removal, suggesting that the HIV promoter is epigenetically repressed. Critically, dCA inhibits viral reactivation upon CD3/CD28 or prostratin stimulation of latently infected CD4+ T cells from HIV-infected subjects receiving suppressive ART. Our results suggest that inclusion of a Tat inhibitor in current ART regimens may contribute to a functional HIV-1 cure by reducing low-level viremia and preventing viral reactivation from latent reservoirs. Antiretroviral therapy (ART) reduces HIV-1 replication to very low levels, but the virus persists in latently infected memory CD4+ T cells, representing a long-lasting source of resurgent virus upon ART interruption. Based on the mode of action of didehydro-cortistatin A (dCA), a Tat-dependent transcription inhibitor, our work highlights an alternative approach to current HIV-1 eradication strategies to decrease the latent reservoir. In our model, dCA blocks the Tat feedback loop initiated after low-level basal reactivation, blocking transcriptional elongation and hence viral production from latently infected cells. Therefore, dCA combined with ART would be aimed at delaying or halting ongoing viral replication, reactivation, and replenishment of the latent viral reservoir. Thus, the latent pool of cells in an infected individual would be stabilized, and death of the long-lived infected memory T cells would result in a continuous decay of this pool over time, possibly culminating in the long-awaited sterilizing cure.
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15
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Beishline K, Azizkhan-Clifford J. Sp1 and the 'hallmarks of cancer'. FEBS J 2015; 282:224-58. [PMID: 25393971 DOI: 10.1111/febs.13148] [Citation(s) in RCA: 369] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 09/26/2014] [Accepted: 11/10/2014] [Indexed: 12/19/2022]
Abstract
For many years, transcription factor Sp1 was viewed as a basal transcription factor and relegated to a role in the regulation of so-called housekeeping genes. Identification of Sp1's role in recruiting the general transcription machinery in the absence of a TATA box increased its importance in gene regulation, particularly in light of recent estimates that the majority of mammalian genes lack a TATA box. In this review, we briefly consider the history of Sp1, the founding member of the Sp family of transcription factors. We review the evidence suggesting that Sp1 is highly regulated by post-translational modifications that positively and negatively affect the activity of Sp1 on a wide array of genes. Sp1 is over-expressed in many cancers and is associated with poor prognosis. Targeting Sp1 in cancer treatment has been suggested; however, our review of the literature on the role of Sp1 in the regulation of genes that contribute to the 'hallmarks of cancer' illustrates the extreme complexity of Sp1 functions. Sp1 both activates and suppresses the expression of a number of essential oncogenes and tumor suppressors, as well as genes involved in essential cellular functions, including proliferation, differentiation, the DNA damage response, apoptosis, senescence and angiogenesis. Sp1 is also implicated in inflammation and genomic instability, as well as epigenetic silencing. Given the apparently opposing effects of Sp1, a more complete understanding of the function of Sp1 in cancer is required to validate its potential as a therapeutic target.
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Affiliation(s)
- Kate Beishline
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
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Hau PM, Deng W, Jia L, Yang J, Tsurumi T, Chiang AKS, Huen MSY, Tsao SW. Role of ATM in the formation of the replication compartment during lytic replication of Epstein-Barr virus in nasopharyngeal epithelial cells. J Virol 2015; 89:652-68. [PMID: 25355892 PMCID: PMC4301132 DOI: 10.1128/jvi.01437-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 10/10/2014] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED Epstein-Barr virus (EBV), a type of oncogenic herpesvirus, is associated with human malignancies. Previous studies have shown that lytic reactivation of EBV in latently infected cells induces an ATM-dependent DNA damage response (DDR). The involvement of ATM activation has been implicated in inducing viral lytic gene transcription to promote lytic reactivation. Its contribution to the formation of a replication compartment during lytic reactivation of EBV remains poorly defined. In this study, the role of ATM in viral DNA replication was investigated in EBV-infected nasopharyngeal epithelial cells. We observed that induction of lytic infection of EBV triggers ATM activation and localization of DDR proteins at the viral replication compartments. Suppression of ATM activity using a small interfering RNA (siRNA) approach or a specific chemical inhibitor profoundly suppressed replication of EBV DNA and production of infectious virions in EBV-infected cells induced to undergo lytic reactivation. We further showed that phosphorylation of Sp1 at the serine-101 residue is essential in promoting the accretion of EBV replication proteins at the replication compartment, which is crucial for replication of viral DNA. Knockdown of Sp1 expression by siRNA effectively suppressed the replication of viral DNA and localization of EBV replication proteins to the replication compartments. Our study supports an important role of ATM activation in lytic reactivation of EBV in epithelial cells, and phosphorylation of Sp1 is an essential process downstream of ATM activation involved in the formation of viral replication compartments. Our study revealed an essential role of the ATM-dependent DDR pathway in lytic reactivation of EBV, suggesting a potential antiviral replication strategy using specific DDR inhibitors. IMPORTANCE Epstein-Barr virus (EBV) is closely associated with human malignancies, including undifferentiated nasopharyngeal carcinoma (NPC), which has a high prevalence in southern China. EBV can establish either latent or lytic infection depending on the cellular context of infected host cells. Recent studies have highlighted the importance of the DNA damage response (DDR), a surveillance mechanism that evolves to maintain genome integrity, in regulating lytic EBV replication. However, the underlying molecular events are largely undefined. ATM is consistently activated in EBV-infected epithelial cells when they are induced to undergo lytic reactivation. Suppression of ATM inhibits replication of viral DNA. Furthermore, we observed that phosphorylation of Sp1 at the serine-101 residue, a downstream event of ATM activation, plays an essential role in the formation of viral replication compartments for replication of virus DNA. Our study provides new insights into the mechanism through which EBV utilizes the host cell machinery to promote replication of viral DNA upon lytic reactivation.
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Affiliation(s)
- Pok Man Hau
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Wen Deng
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Lin Jia
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Jie Yang
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Tatsuya Tsurumi
- Division of Virology, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Alan Kwok Shing Chiang
- Department of Pediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
| | - Michael Shing-Yan Huen
- Genome Stability Research Laboratory, Department of Anatomy and Centre for Cancer Research, The University of Hong Kong, Hong Kong SAR
| | - Sai Wah Tsao
- Department of Anatomy and Center for Cancer Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
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Yang HC, Chuang JY, Jeng WY, Liu CI, Wang AHJ, Lu PJ, Chang WC, Hung JJ. Pin1-mediated Sp1 phosphorylation by CDK1 increases Sp1 stability and decreases its DNA-binding activity during mitosis. Nucleic Acids Res 2014; 42:13573-87. [PMID: 25398907 PMCID: PMC4267622 DOI: 10.1093/nar/gku1145] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 10/27/2014] [Accepted: 10/27/2014] [Indexed: 11/15/2022] Open
Abstract
We have shown that Sp1 phosphorylation at Thr739 decreases its DNA-binding activity. In this study, we found that phosphorylation of Sp1 at Thr739 alone is necessary, but not sufficient for the inhibition of its DNA-binding activity during mitosis. We demonstrated that Pin1 could be recruited to the Thr739(p)-Pro motif of Sp1 to modulate the interaction between phospho-Sp1 and CDK1, thereby facilitating CDK1-mediated phosphorylation of Sp1 at Ser720, Thr723 and Thr737 during mitosis. Loss of the C-terminal end of Sp1 (amino acids 741-785) significantly increased Sp1 phosphorylation, implying that the C-terminus inhibits CDK1-mediated Sp1 phosphorylation. Binding analysis of Sp1 peptides to Pin1 by isothermal titration calorimetry indicated that Pin1 interacts with Thr739(p)-Sp1 peptide but not with Thr739-Sp1 peptide. X-ray crystallography data showed that the Thr739(p)-Sp1 peptide occupies the active site of Pin1. Increased Sp1 phosphorylation by CDK1 during mitosis not only stabilized Sp1 levels by decreasing interaction with ubiquitin E3-ligase RNF4 but also caused Sp1 to move out of the chromosomes completely by decreasing its DNA-binding activity, thereby facilitating cell cycle progression. Thus, Pin1-mediated conformational changes in the C-terminal region of Sp1 are critical for increased CDK1-mediated Sp1 phosphorylation to facilitate cell cycle progression during mitosis.
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Affiliation(s)
- Hang-Che Yang
- Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan
| | - Jian-Ying Chuang
- The PhD Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Wen-Yih Jeng
- Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan
| | - Chia-I Liu
- Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei 110, Taiwan
| | - Andrew H-J Wang
- Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
| | - Pei-Jung Lu
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, Tainan 70403, Taiwan
| | - Wen-Chang Chang
- Graduate Institute of Medical Sciences, College of Medicine, and Center for Neurotrauma and Neuroregeneration, Taipei Medical University, Taipei 110, Taiwan
| | - Jan-Jong Hung
- Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei 110, Taiwan Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan Center for Infectious Disease and Signal Transduction Research, National Cheng Kung University, Tainan 701, Taiwan
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Phenyl-1-Pyridin-2yl-ethanone-based iron chelators increase IκB-α expression, modulate CDK2 and CDK9 activities, and inhibit HIV-1 transcription. Antimicrob Agents Chemother 2014; 58:6558-71. [PMID: 25155598 DOI: 10.1128/aac.02918-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
HIV-1 transcription is activated by the Tat protein, which recruits CDK9/cyclin T1 to the HIV-1 promoter. CDK9 is phosphorylated by CDK2, which facilitates formation of the high-molecular-weight positive transcription elongation factor b (P-TEFb) complex. We previously showed that chelation of intracellular iron inhibits CDK2 and CDK9 activities and suppresses HIV-1 transcription, but the mechanism of the inhibition was not understood. In the present study, we tested a set of novel iron chelators for the ability to inhibit HIV-1 transcription and elucidated their mechanism of action. Novel phenyl-1-pyridin-2yl-ethanone (PPY)-based iron chelators were synthesized and examined for their effects on cellular iron, HIV-1 inhibition, and cytotoxicity. Activities of CDK2 and CDK9, expression of CDK9-dependent and CDK2-inhibitory mRNAs, NF-κB expression, and HIV-1- and NF-κB-dependent transcription were determined. PPY-based iron chelators significantly inhibited HIV-1, with minimal cytotoxicity, in cultured and primary cells chronically or acutely infected with HIV-1 subtype B, but they had less of an effect on HIV-1 subtype C. Iron chelators upregulated the expression of IκB-α, with increased accumulation of cytoplasmic NF-κB. The iron chelators inhibited CDK2 activity and reduced the amount of CDK9/cyclin T1 in the large P-TEFb complex. Iron chelators reduced HIV-1 Gag and Env mRNA synthesis but had no effect on HIV-1 reverse transcription. In addition, iron chelators moderately inhibited basal HIV-1 transcription, equally affecting HIV-1 and Sp1- or NF-κB-driven transcription. By virtue of their involvement in targeting several key steps in HIV-1 transcription, these novel iron chelators have the potential for the development of new therapeutics for the treatment of HIV-1 infection.
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Kukkonen S, Martinez-Viedma MDP, Kim N, Manrique M, Aldovini A. HIV-1 Tat second exon limits the extent of Tat-mediated modulation of interferon-stimulated genes in antigen presenting cells. Retrovirology 2014; 11:30. [PMID: 24742347 PMCID: PMC4036831 DOI: 10.1186/1742-4690-11-30] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 03/27/2014] [Indexed: 12/14/2022] Open
Abstract
Background We have shown that HIV-1 Tat interaction with MAP2K3, MAP2K6, and IRF7 promoters is key to IFN-stimulated genes (ISG) activation in immature dendritic cells and macrophages. Results We evaluated how Tat alleles and mutants differ in cellular gene modulation of immature dendritic cells and monocyte-derived macrophages and what similarities this modulation has with that induced by interferons. The tested alleles and mutants modulated to different degrees ISG, without concomitant induction of interferons. The first exon TatSF21-72 and the minimal transactivator TatSF21-58, all modulated genes to a significantly greater extent than full-length wild type, two-exon Tat, indicating that Tat second exon is critical in reducing the innate response triggered by HIV-1 in these cells. Mutants with reduced LTR transactivation had a substantially reduced effect on host gene expression modulation than wild type TatSF2. However, the more potent LTR transactivator TatSF2A58T modulated ISG expression to a lower degree compared to TatSF2. A cellular gene modulation similar to that induced by Tat and Tat mutants in immature dendritic cells could be observed in monocyte-derived macrophages, with the most significant pathways affected by Tat being the same in both cell types. Tat expression in cells deleted of the type I IFN locus or receptor resulted in a gene modulation pattern similar to that induced in primary immature dendritic cells and monocyte-derived macrophages, excluding the involvement of type I IFNs in Tat-mediated gene modulation. ISG activation depends on Tat interaction with MAP2K3, MAP2K6, and IRF7 promoters and a single exon Tat protein more strongly modulated the luciferase activity mediated by MAP2K3, MAP2K6, and IRF7 promoter sequences located 5′ of the RNA start site than the wild type two-exon Tat, while a cysteine and lysine Tat mutants, reduced in LTR transactivation, had negligible effects on these promoters. Chemical inhibition of CDK9 or Sp1 decreased Tat activation of MAP2K3-, MAP2K6-, and IRF7-mediated luciferase transcription. Conclusions Taken together, these data indicate that the second exon of Tat is critical to the containment of the innate response stimulated by Tat in antigen presenting cells and support a role for Tat in stimulating cellular transcription via its interaction with transcription factors present at promoters.
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Affiliation(s)
| | | | | | | | - Anna Aldovini
- Department of Pediatrics, Harvard Medical School, Department of Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
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Bruce JW, Reddington R, Mathieu E, Bracken M, Young JAT, Ahlquist P. ZASC1 stimulates HIV-1 transcription elongation by recruiting P-TEFb and TAT to the LTR promoter. PLoS Pathog 2013; 9:e1003712. [PMID: 24204263 PMCID: PMC3812036 DOI: 10.1371/journal.ppat.1003712] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 08/30/2013] [Indexed: 01/11/2023] Open
Abstract
Transcription from the HIV-1 LTR promoter efficiently initiates but rapidly terminates because of a non-processive form of RNA polymerase II. This premature termination is overcome by assembly of an HIV-1 TAT/P-TEFb complex at the transactivation response region (TAR), a structured RNA element encoded by the first 59 nt of HIV-1 mRNA. Here we have identified a conserved DNA-binding element for the cellular transcription factor, ZASC1, in the HIV-1 core promoter immediately upstream of TAR. We show that ZASC1 interacts with TAT and P-TEFb, co-operating with TAT to regulate HIV-1 gene expression, and promoting HIV-1 transcriptional elongation. The importance of ZASC1 to HIV-1 transcription elongation was confirmed through mutagenesis of the ZASC1 binding sites in the LTR promoter, shRNAs targeting ZASC1 and expression of dominant negative ZASC1. Chromatin immunoprecipitation analysis revealed that ZASC1 recruits Tat and P-TEFb to the HIV-1 core promoter in a TAR-independent manner. Thus, we have identified ZASC1 as novel regulator of HIV-1 gene expression that functions through the DNA-dependent, RNA-independent recruitment of TAT/P-TEFb to the HIV-1 promoter.
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Affiliation(s)
- James W. Bruce
- Morgridge Institute for Research, Madison, Wisconsin, United States of America
- Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin, United States of America
- McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Rachel Reddington
- Morgridge Institute for Research, Madison, Wisconsin, United States of America
- Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin, United States of America
- Howard Hughes Medical Institute, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Elizabeth Mathieu
- Morgridge Institute for Research, Madison, Wisconsin, United States of America
- Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Megan Bracken
- Morgridge Institute for Research, Madison, Wisconsin, United States of America
- Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - John A. T. Young
- Nomis Foundation Laboratories for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Paul Ahlquist
- Morgridge Institute for Research, Madison, Wisconsin, United States of America
- Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin, United States of America
- McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, Wisconsin, United States of America
- Howard Hughes Medical Institute, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail:
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Functional role of post-translational modifications of Sp1 in tumorigenesis. J Biomed Sci 2012; 19:94. [PMID: 23148884 PMCID: PMC3503885 DOI: 10.1186/1423-0127-19-94] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 10/03/2012] [Indexed: 12/17/2022] Open
Abstract
Specific protein 1 (Sp1), the first transcription factor to be isolated, regulates the expression of numerous genes involved in cell proliferation, apoptosis, and differentiation. Recent studies found that an increase in Sp1 transcriptional activity is associated with the tumorigenesis. Moreover, post-translational modifications of Sp1, including glycosylation, phosphorylation, acetylation, sumoylation, ubiquitination, and methylation, regulate Sp1 transcriptional activity and modulate target gene expression by affecting its DNA binding activity, transactivation activity, or protein level. In addition, recent studies have investigated several compounds with anti-cancer activity that could inhibit Sp1 transcriptional activity. In this review, we describe the effect of various post-translational modifications on Sp1 transcriptional activity and discuss compounds that inhibit the activity of Sp1.
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22
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Transcriptional regulation by post-transcriptional modification—Role of phosphorylation in Sp1 transcriptional activity. Gene 2012; 508:1-8. [DOI: 10.1016/j.gene.2012.07.022] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 05/22/2012] [Accepted: 07/16/2012] [Indexed: 01/05/2023]
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Impact of Tat Genetic Variation on HIV-1 Disease. Adv Virol 2012; 2012:123605. [PMID: 22899925 PMCID: PMC3414192 DOI: 10.1155/2012/123605] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 05/14/2012] [Indexed: 01/08/2023] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) promoter or long-terminal repeat (LTR) regulates viral gene expression by interacting with multiple viral and host factors. The viral transactivator protein Tat plays an important role in transcriptional activation of HIV-1 gene expression. Functional domains of Tat and its interaction with transactivation response element RNA and cellular transcription factors have been examined. Genetic variation within tat of different HIV-1 subtypes has been shown to affect the interaction of the viral transactivator with cellular and/or viral proteins, influencing the overall level of transcriptional activation as well as its action as a neurotoxic protein. Consequently, the genetic variability within tat may impact the molecular architecture of functional domains of the Tat protein that may impact HIV pathogenesis and disease. Tat as a therapeutic target for anti-HIV drugs has also been discussed.
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Ammosova T, Platonov M, Yedavalli VRK, Obukhov Y, Gordeuk VR, Jeang KT, Kovalskyy D, Nekhai S. Small molecules targeted to a non-catalytic "RVxF" binding site of protein phosphatase-1 inhibit HIV-1. PLoS One 2012; 7:e39481. [PMID: 22768081 PMCID: PMC3387161 DOI: 10.1371/journal.pone.0039481] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 05/22/2012] [Indexed: 11/18/2022] Open
Abstract
HIV-1 Tat protein recruits host cell factors including CDK9/cyclin T1 to HIV-1 TAR RNA and thereby induces HIV-1 transcription. An interaction with host Ser/Thr protein phosphatase-1 (PP1) is critical for this function of Tat. PP1 binds to a Tat sequence, Q35VCF38, which resembles the PP1-binding “RVxF” motif present on PP1-binding regulatory subunits. We showed that expression of PP1 binding peptide, a central domain of Nuclear Inhibitor of PP1, disrupted the interaction of HIV-1 Tat with PP1 and inhibited HIV-1 transcription and replication. Here, we report small molecule compounds that target the “RVxF”-binding cavity of PP1 to disrupt the interaction of PP1 with Tat and inhibit HIV-1 replication. Using the crystal structure of PP1, we virtually screened 300,000 compounds and identified 262 small molecules that were predicted to bind the “RVxF”-accommodating cavity of PP1. These compounds were then assayed for inhibition of HIV-1 transcription in CEM T cells. One of the compounds, 1H4, inhibited HIV-1 transcription and replication at non-cytotoxic concentrations. 1H4 prevented PP1-mediated dephosphorylation of a substrate peptide containing an RVxF sequence in vitro. 1H4 also disrupted the association of PP1 with Tat in cultured cells without having an effect on the interaction of PP1 with the cellular regulators, NIPP1 and PNUTS, or on the cellular proteome. Finally, 1H4 prevented the translocation of PP1 to the nucleus. Taken together, our study shows that HIV- inhibition can be achieved through using small molecules to target a non-catalytic site of PP1. This proof-of-principle study can serve as a starting point for the development of novel antiviral drugs that target the interface of HIV-1 viral proteins with their host partners.
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Affiliation(s)
- Tatiana Ammosova
- Center for Sickle Cell Disease, Howard University, Washington, D.C., United States of America
- RCMI Proteomics Core Facility, Howard University, Washington, D.C., United States of America
- Department of Medicine, Howard University, Washington, D.C., United States of America
| | - Maxim Platonov
- ChemBio Center, National Taras Shevchenko University, Kiev, Ukraine
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kiev, Ukraine
| | - Venkat R. K. Yedavalli
- Molecular Virology Section, Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yuri Obukhov
- RCMI Proteomics Core Facility, Howard University, Washington, D.C., United States of America
| | - Victor R. Gordeuk
- Center for Sickle Cell Disease, Howard University, Washington, D.C., United States of America
- Sickle Cell Center, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Kuan-Teh Jeang
- Molecular Virology Section, Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Dmytro Kovalskyy
- ChemBio Center, National Taras Shevchenko University, Kiev, Ukraine
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kiev, Ukraine
| | - Sergei Nekhai
- Center for Sickle Cell Disease, Howard University, Washington, D.C., United States of America
- RCMI Proteomics Core Facility, Howard University, Washington, D.C., United States of America
- Department of Medicine, Howard University, Washington, D.C., United States of America
- * E-mail:
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Dey SS, Xue Y, Joachimiak MP, Friedland GD, Burnett JC, Zhou Q, Arkin AP, Schaffer DV. Mutual information analysis reveals coevolving residues in Tat that compensate for two distinct functions in HIV-1 gene expression. J Biol Chem 2012; 287:7945-55. [PMID: 22253435 DOI: 10.1074/jbc.m111.302653] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Viral genomes are continually subjected to mutations, and functionally deleterious ones can be rescued by reversion or additional mutations that restore fitness. The error prone nature of HIV-1 replication has resulted in highly diverse viral sequences, and it is not clear how viral proteins such as Tat, which plays a critical role in viral gene expression and replication, retain their complex functions. Although several important amino acid positions in Tat are conserved, we hypothesized that it may also harbor functionally important residues that may not be individually conserved yet appear as correlated pairs, whose analysis could yield new mechanistic insights into Tat function and evolution. To identify such sites, we combined mutual information analysis and experimentation to identify coevolving positions and found that residues 35 and 39 are strongly correlated. Mutation of either residue of this pair into amino acids that appear in numerous viral isolates yields a defective virus; however, simultaneous introduction of both mutations into the heterologous Tat sequence restores gene expression close to wild-type Tat. Furthermore, in contrast to most coevolving protein residues that contribute to the same function, structural modeling and biochemical studies showed that these two residues contribute to two mechanistically distinct steps in gene expression: binding P-TEFb and promoting P-TEFb phosphorylation of the C-terminal domain in RNAPII. Moreover, Tat variants that mimic HIV-1 subtypes B or C at sites 35 and 39 have evolved orthogonal strengths of P-TEFb binding versus RNAPII phosphorylation, suggesting that subtypes have evolved alternate transcriptional strategies to achieve similar gene expression levels.
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Affiliation(s)
- Siddharth S Dey
- Department of Chemical and Biomolecular Engineering and the Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA
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Law AYS, Yeung BHY, Ching LY, Wong CKC. Sp1 is a transcription repressor to stanniocalcin-1 expression in TSA-treated human colon cancer cells, HT29. J Cell Biochem 2011; 112:2089-96. [PMID: 21465530 DOI: 10.1002/jcb.23127] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Our previous study demonstrated that, stanniocalcin-1 (STC1) was a target of histone deacetylase (HDAC) inhibitors and was involved in trichostatin A (TSA) induced apoptosis in the human colon cancer cells, HT29. In this study, we reported that the transcriptional factor, specificity protein 1 (Sp1) in association with retinoblastoma (Rb) repressed STC1 gene transcription in TSA-treated HT29 cells. Our data demonstrated that, a co-treatment of the cells with TSA and Sp1 inhibitor, mithramycin A (MTM) led to a marked synergistic induction of STC1 transcript levels, STC1 promoter (1 kb)-driven luciferase activity and an increase of apoptotic cell population. The knockdown of Sp1 gene expression in TSA treated cells, revealed the repressor role of Sp1 in STC1 transcription. Using a protein phosphatase inhibitor okadaic acid (OKA), an increase of Sp1 hyperphosphorylation and so a reduction of its transcriptional activity, led to a significant induction of STC1 gene expression. Chromatin immunoprecipitation (ChIP) assay revealed that Sp1 binding on STC1 proximal promoter in TSA treated cells. The binding of Sp1 to STC1 promoter was abolished by the co-treatment of MTM or OKA in TSA-treated cells. Re-ChIP assay illustrated that Sp1-mediated inhibition of STC1 transcription was associated with the recruitment of another repressor molecule, Rb. Collectively our findings identify STC1 is a downstream target of Sp1.
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Affiliation(s)
- Alice Y S Law
- Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong
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Waby JS, Bingle CD, Corfe BM. Post-translational control of sp-family transcription factors. Curr Genomics 2011; 9:301-11. [PMID: 19471608 PMCID: PMC2685645 DOI: 10.2174/138920208785133244] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 05/14/2008] [Accepted: 05/15/2008] [Indexed: 11/22/2022] Open
Abstract
Sp-family transcription factors are widely expressed in human tissues and involved in the regulation of many cellular processes and response to cellular microenvironment. These responses appear to be mediated by alterations in transcription factor affinity for DNA rather than altered protein level. How might such changes be effected? This review will identify the range of known post-translational modifications (PTMs) of Sp-factors and the sometimes conflicting literature about the roles of PTMs in regulating activity. We will speculate on the interaction between cell environment, chromatin microenvironment and the role of PTM in governing functionality of the proteins and the complexes to which they belong.
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Affiliation(s)
- J S Waby
- School of Medicine and Biomedical Sciences, University of Sheffield, Royal Hallamshire Hospital, Sheffield, S10 2JF, UK
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Abstract
It is generally acknowledged that the Tat protein has a pivotal role in HIV-1 replication because it stimulates transcription from the viral long terminal repeat (LTR) promoter by binding to the TAR hairpin in the nascent RNA transcript. However, a multitude of additional Tat functions have been suggested. The importance of these functions is difficult to assess in replication studies with Tat-mutated HIV-1 variants because of the dominant negative effect on viral gene expression. We therefore used an HIV-1 construct that does not depend on the Tat-TAR interaction for transcription to reevaluate whether or not Tat has a second essential function in HIV-1 replication. This HIV-rtTA variant uses the incorporated Tet-On gene expression system for activation of transcription and replicates efficiently upon complete TAR deletion. Here we demonstrated that Tat inactivation does nevertheless severely inhibit replication. Upon long-term culturing, the Tat-minus HIV-rtTA variant acquired mutations in the U3 region that improved promoter activity and reestablished replication. We showed that in the absence of a functional TAR, Tat remains important for viral transcription via Sp1 sequence elements in the U3 promoter region. Substitution of these U3 sequences with nonrelated promoter elements created a virus that replicates efficiently without Tat in SupT1 T cells. These results indicate that Tat has a versatile role in transcription via TAR and U3 elements. The results also imply that Tat has no other essential function in viral replication in cultured T cells.
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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.
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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
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Tyagi S, Ochem A, Tyagi M. DNA-dependent protein kinase interacts functionally with the RNA polymerase II complex recruited at the human immunodeficiency virus (HIV) long terminal repeat and plays an important role in HIV gene expression. J Gen Virol 2011; 92:1710-1720. [PMID: 21450944 DOI: 10.1099/vir.0.029587-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
DNA-dependent protein kinase (DNA-PK), a nuclear protein kinase that specifically requires association with DNA for its kinase activity, plays important roles in the regulation of different DNA transactions, including transcription, replication and DNA repair, as well as in the maintenance of telomeres. Due to its large size, DNA-PK is also known to facilitate the activities of other factors by providing the docking platform at their site of action. In this study, by running several chromatin immunoprecipitation assays, we demonstrate the parallel distribution of DNA-PK with RNA polymerase II (RNAP II) along the human immunodeficiency virus (HIV) provirus before and after activation with tumour necrosis factor alpha. The association between DNA-PK and RNAP II is also long-lasting, at least for up to 4 h (the duration analysed in this study). Knockdown of endogenous DNA-PK using specific small hairpin RNAs expressed from lentiviral vectors resulted in significant reduction in HIV gene expression and replication, demonstrating the importance of DNA-PK for HIV gene expression. Sequence analysis of the HIV-1 Tat protein revealed three potential target sites for phosphorylation by DNA-PK and, by using kinase assays, we confirmed that Tat is an effective substrate of DNA-PK. Through peptide mapping, we found that two of these three potential phosphorylation sites are recognized and phosphorylated by DNA-PK. Mutational studies on the DNA-PK target sites of Tat further demonstrated the functional significance of the Tat-DNA-PK interaction. Thus, overall our results clearly demonstrate the functional interaction between DNA-PK and RNAP II during HIV transcription.
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Affiliation(s)
- Shilpi Tyagi
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Wernher and Beit Building (South), Anzio Road, Observatory 7925, Cape Town, South Africa.,National Center for Biodefense and Infectious Diseases, George Mason University, Biomedical Research Laboratory, 10650 Pyramid Place, MS 1J5, Manassas, VA 20110, USA
| | - Alex Ochem
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Wernher and Beit Building (South), Anzio Road, Observatory 7925, Cape Town, South Africa
| | - Mudit Tyagi
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Adelbert Road, Cleveland, OH 44106, USA.,National Center for Biodefense and Infectious Diseases, George Mason University, Biomedical Research Laboratory, 10650 Pyramid Place, MS 1J5, Manassas, VA 20110, USA
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Xu J, Zhu D, He S, Spee C, Ryan SJ, Hinton DR. Transcriptional regulation of bone morphogenetic protein 4 by tumor necrosis factor and its relationship with age-related macular degeneration. FASEB J 2011; 25:2221-33. [PMID: 21411747 DOI: 10.1096/fj.10-178350] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bone morphogenetic protein-4 (BMP4) may be involved in the molecular switch that determines which late form of age-related macular degeneration (AMD) an individual develops. BMP4 expression is high in retinal pigment epithelium (RPE) cells in late, dry AMD patients, while BMP4 expression is low in the wet form of the disease, characterized by choroidal neovascularization (CNV). Here, we sought to determine the mechanism by which BMP4 is down-regulated in CNV. BMP4 expression was decreased within laser-induced CNV lesions in mice at a time when tumor necrosis factor (TNF) expression was high (7 d postlaser) and was reexpressed in RPE when TNF levels declined (14 d postlaser). We found that TNF, an important angiogenic stimulus, significantly down-regulates BMP4 expression in cultured human fetal RPE cells, ARPE-19 cells, and RPE cells in murine posterior eye cup explants. We identified two specificity protein 1 (Sp1) binding sites in the BMP4 promoter that are required for basal expression of BMP4 and its down-regulation by TNF. Through c-Jun NH(2)-terminal kinase (JNK) activation, TNF modulates Sp1 phosphorylation, thus decreasing its affinity to the BMP4 promoter. The down-regulation of BMP4 expression by TNF in CNV and mechanisms established might be useful for defining novel targets for AMD therapy.
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Affiliation(s)
- Jing Xu
- Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
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González OA, Ebersole JL, Huang CB. The oral commensal, Streptococcus gordonii, synergizes with Tat protein to induce HIV-1 promoter activation in monocytes/macrophages. Cell Immunol 2011; 269:38-45. [PMID: 21459369 DOI: 10.1016/j.cellimm.2011.03.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 02/24/2011] [Accepted: 03/09/2011] [Indexed: 01/02/2023]
Abstract
Trans-activator of transcription (Tat) is an HIV-1 protein essential for viral replication. Oral periodontopathogens (e.g. Fusobacterium nucleatum) enhance HIV-1LTR promoter activation in monocytes/macrophages in absence of Tat; however, some oral commensals fail to trigger this response. We sought to determine the effect of Tat on HIV-1LTR promoter activation induced by the representative oral commensal Streptococcus gordonii in monocytes/macrophages. S. gordonii enhanced HIV-1LTR reactivation in THP89GFP (Tat(+)), but not in BF24 (Tat(-)) cells. Interestingly, S. gordonii, but not Streptococcus sanguinis enhanced HIV-1LTR activation in the presence of recombinant Tat in BF24 cells. This response correlated with IL-8 but not TNFα or IL-6 production, and was abrogated by the NFκB inhibitor BAY 11-7082. Kinetics of NFκB-RelA activation did not explain the S. gordonii-induced HIV-1LTR activation in presence of Tat. These results suggest that S. gordonii-induced HIV-1 reactivation in monocytes/macrophages is Tat-dependent and appears to involve NFκB activation.
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Affiliation(s)
- Octavio A González
- Center for Oral Health Research, College of Dentistry, University of Kentucky, Lexington, KY, USA.
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Interplay between PKCδ and Sp1 on histone deacetylase inhibitor-mediated Epstein-Barr virus reactivation. J Virol 2010; 85:2373-85. [PMID: 21159880 DOI: 10.1128/jvi.01602-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Epstein-Barr virus (EBV) undergoes latent and lytic replication cycles, and its reactivation from latency to lytic replication is initiated by expression of the two viral immediate-early transactivators, Zta and Rta. In vitro, reactivation of EBV can be induced by anti-immunoglobulin, tetradecanoyl phorbol acetate, and histone deacetylase inhibitor (HDACi). We have discovered that protein kinase C delta (PKCδ) is required specifically for EBV reactivation by HDACi. Overexpression of PKCδ is sufficient to induce the activity of the Zta promoter (Zp) but not of the Rta promoter (Rp). Deletion analysis revealed that the ZID element of Zp is important for PKCδ activation. Moreover, the Sp1 putative sequence on ZID is essential for PKCδ-induced Zp activity, and the physiological binding of Sp1 on ZID has been confirmed. After HDACi treatment, activated PKCδ can phosphorylate Sp1 at serine residues and might result in dissociation of the HDAC2 repressor from ZID. HDACi-mediated HDAC2-Sp1 dissociation can be inhibited by the PKCδ inhibitor, Rotterlin. Furthermore, overexpression of HDAC2 can suppress the HDACi-induced Zp activity. Consequently, we hypothesize that HDACi induces PKCδ activation, causing phosphorylation of Sp1, and that the interplay between PKCδ and Sp1 results in the release of HDAC2 repressor from Zp and initiation of Zta expression.
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Ammosova T, Yedavalli VRK, Niu X, Jerebtsova M, Van Eynde A, Beullens M, Bollen M, Jeang KT, Nekhai S. Expression of a protein phosphatase 1 inhibitor, cdNIPP1, increases CDK9 threonine 186 phosphorylation and inhibits HIV-1 transcription. J Biol Chem 2010; 286:3798-804. [PMID: 21098020 DOI: 10.1074/jbc.m110.196493] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
CDK9/cyclin T1, a key enzyme in HIV-1 transcription, is negatively regulated by 7SK RNA and the HEXIM1 protein. Dephosphorylation of CDK9 on Thr(186) by protein phosphatase 1 (PP1) in stress-induced cells or by protein phosphatase M1A in normally growing cells activates CDK9. Our previous studies showed that HIV-1 Tat protein binds to PP1 through the Tat Q(35)VCF(38) sequence, which is similar to the PP1-binding RVXF motif and that this interaction facilitates HIV-1 transcription. In the present study, we analyzed the effect of expression of the central domain of nuclear inhibitor of PP1 (cdNIPP1) in an engineered cell line and also when cdNIPP1 was expressed as part of HIV-1 pNL4-3 in place of nef. Stable expression of cdNIPP1 increased CDK9 phosphorylation on Thr(186) and the association of CDK9 with 7SK RNA. The stable expression of cdNIPP1 disrupted the interaction of Tat and PP1 and inhibited HIV-1 transcription. Expression of cdNIPP1 as a part of the HIV-1 genome inhibited HIV-1 replication. Our study provides a proof-of-concept for the future development of PP1-targeting compounds as inhibitors of HIV-1 replication.
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Affiliation(s)
- Tatiana Ammosova
- Center for Sickle Cell Disease, Howard University, Washington, DC 20001, USA
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Debebe Z, Ammosova T, Breuer D, Lovejoy DB, Kalinowski DS, Kumar K, Jerebtsova M, Ray P, Kashanchi F, Gordeuk VR, Richardson DR, Nekhai S. Iron chelators of the di-2-pyridylketone thiosemicarbazone and 2-benzoylpyridine thiosemicarbazone series inhibit HIV-1 transcription: identification of novel cellular targets--iron, cyclin-dependent kinase (CDK) 2, and CDK9. Mol Pharmacol 2010; 79:185-96. [PMID: 20956357 DOI: 10.1124/mol.110.069062] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
HIV-1 transcription is activated by HIV-1 Tat protein, which recruits cyclin-dependent kinase 9 (CDK9)/cyclin T1 and other host transcriptional coactivators to the HIV-1 promoter. Tat itself is phosphorylated by CDK2, and inhibition of CDK2 by small interfering RNA, the iron chelator 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311), and the iron chelator deferasirox (ICL670) inhibits HIV-1 transcription. Here we have analyzed a group of novel di-2-pyridylketone thiosemicarbazone- and 2-benzoylpyridine thiosemicarbazone-based iron chelators that exhibit marked anticancer activity in vitro and in vivo (Proc Natl Acad Sci USA 103:7670-7675, 2006; J Med Chem 50:3716-3729, 2007). Several of these iron chelators, in particular 2-benzoylpyridine 4-allyl-3-thiosemicarbazone (Bp4aT) and 2-benzoylpyridine 4-ethyl-3-thiosemicarbazone (Bp4eT), inhibited HIV-1 transcription and replication at much lower concentrations than did 311 and ICL670. Neither Bp4aT nor Bp4eT were toxic after a 24-h incubation. However, longer incubations for 48 h or 72 h resulted in cytotoxicity. Analysis of the molecular mechanism of HIV-1 inhibition showed that the novel iron chelators inhibited basal HIV-1 transcription, but not the nuclear factor-κB-dependent transcription or transcription from an HIV-1 promoter with inactivated SP1 sites. The chelators inhibited the activities of CDK2 and CDK9/cyclin T1, suggesting that inhibition of CDK9 may contribute to the inhibition of HIV-1 transcription. Our study suggests the potential usefulness of Bp4aT or Bp4eT in antiretroviral regimens, particularly where resistance to standard treatment occurs.
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Affiliation(s)
- Zufan Debebe
- Center for Sickle Cell Disease, Department of Medicine, Howard University, Washington DC 20001, USA
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HIV-1 reactivation induced by the periodontal pathogens Fusobacterium nucleatum and Porphyromonas gingivalis involves Toll-like receptor 2 [corrected] and 9 activation in monocytes/macrophages. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 17:1417-27. [PMID: 20610663 DOI: 10.1128/cvi.00009-10] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Although oral coinfections (e.g., periodontal disease) are highly prevalent in human immunodeficiency virus type 1-positive (HIV-1(+)) patients and appear to positively correlate with viral load levels, the potential for oral bacteria to induce HIV-1 reactivation in latently infected cells has received little attention. We showed that HIV-1 long terminal repeat (LTR) promoter activation can be induced by periodontopathogens in monocytes/macrophages; nevertheless, the mechanisms involved in this response remain undetermined. Since Toll-like receptor 2 (TLR2), TLR4, and TLR9 activation have been involved in HIV-1 recrudescence, we sought to determine the role of these TLRs in HIV-1 reactivation induced by the periodontal pathogens Fusobacterium nucleatum and Porphyromonas gingivalis using BF24 monocytes/macrophages stably transfected with the HIV-1 promoter driving chloramphenicol acetyltransferase (CAT) expression and THP89GFP cells, a model of HIV-1 latency. We demonstrated that TLR9 activation by F. nucleatum and TLR2 activation by both bacteria appear to be involved in HIV-1 reactivation; however, TLR4 activation had no effect. Moreover, the autocrine activity of tumor necrosis factor alpha (TNF-alpha) but not interleukin-1beta (IL-1beta) produced in response to bacteria could impact viral reactivation. The transcription factors NF-kappaB and Sp1 appear to be positively regulating HIV-1 reactivation induced by these oral pathogens. These results suggest that oral Gram-negative bacteria (F. nucleatum and P. gingivalis) associated with oral and systemic chronic inflammatory disorders enhance HIV-1 reactivation in monocytes/macrophages through TLR2 and TLR9 activation in a mechanism that appears to be transcriptionally regulated. Increased bacterial growth and emergence of these bacteria or their products accompanying chronic oral inflammatory diseases could be risk modifiers for viral replication, systemic immune activation, and AIDS progression in HIV-1(+) patients.
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Kilareski EM, Shah S, Nonnemacher MR, Wigdahl B. Regulation of HIV-1 transcription in cells of the monocyte-macrophage lineage. Retrovirology 2009; 6:118. [PMID: 20030845 PMCID: PMC2805609 DOI: 10.1186/1742-4690-6-118] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 12/23/2009] [Indexed: 12/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) has been shown to replicate productively in cells of the monocyte-macrophage lineage, although replication occurs to a lesser extent than in infected T cells. As cells of the monocyte-macrophage lineage become differentiated and activated and subsequently travel to a variety of end organs, they become a source of infectious virus and secreted viral proteins and cellular products that likely initiate pathological consequences in a number of organ systems. During this process, alterations in a number of signaling pathways, including the level and functional properties of many cellular transcription factors, alter the course of HIV-1 long terminal repeat (LTR)-directed gene expression. This process ultimately results in events that contribute to the pathogenesis of HIV-1 infection. First, increased transcription leads to the upregulation of infectious virus production, and the increased production of viral proteins (gp120, Tat, Nef, and Vpr), which have additional activities as extracellular proteins. Increased viral production and the presence of toxic proteins lead to enhanced deregulation of cellular functions increasing the production of toxic cellular proteins and metabolites and the resulting organ-specific pathologic consequences such as neuroAIDS. This article reviews the structural and functional features of the cis-acting elements upstream and downstream of the transcriptional start site in the retroviral LTR. It also includes a discussion of the regulation of the retroviral LTR in the monocyte-macrophage lineage during virus infection of the bone marrow, the peripheral blood, the lymphoid tissues, and end organs such as the brain. The impact of genetic variation on LTR-directed transcription during the course of retrovirus disease is also reviewed.
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Affiliation(s)
- Evelyn M Kilareski
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, 245 N 15th St, Philadelphia, Pennsylvania 19102, USA
- Center for Molecular Therapeutics and Resistance, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, 245 N 15th St, Philadelphia, Pennsylvania 19102, USA
- Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, USA
| | - Sonia Shah
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, 245 N 15th St, Philadelphia, Pennsylvania 19102, USA
- Center for Molecular Therapeutics and Resistance, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, 245 N 15th St, Philadelphia, Pennsylvania 19102, USA
- Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, USA
| | - Michael R Nonnemacher
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, 245 N 15th St, Philadelphia, Pennsylvania 19102, USA
- Center for Molecular Therapeutics and Resistance, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, 245 N 15th St, Philadelphia, Pennsylvania 19102, USA
- Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, USA
| | - Brian Wigdahl
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, 245 N 15th St, Philadelphia, Pennsylvania 19102, USA
- Center for Molecular Therapeutics and Resistance, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, 245 N 15th St, Philadelphia, Pennsylvania 19102, USA
- Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, USA
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Charles S, Ammosova T, Cardenas J, Foster A, Rotimi J, Jerebtsova M, Ayodeji AA, Niu X, Ray PE, Gordeuk VR, Kashanchi F, Nekhai S. Regulation of HIV-1 transcription at 3% versus 21% oxygen concentration. J Cell Physiol 2009; 221:469-79. [PMID: 19626680 DOI: 10.1002/jcp.21882] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
HIV transcription is induced by the HIV-1 Tat protein, in concert with cellular co-factors including CDK9, CDK2, NF-kappaB, and others. The cells of most of the body's organs are exposed to approximately 3-6% oxygen, but most in vitro studies of HIV replication are conducted at 21% oxygen. We hypothesized that activities of host cell factors involved in HIV-1 replication may differ at 3% versus 21% O(2), and that such differences may affect HIV-1 replication. Here we show that Tat-induced HIV-1 transcription was reduced at 3% O(2) compared to 21% O(2). HIV-1 replication was also reduced in acutely or chronically infected cells cultured at 3% O(2) compared to 21% O(2). This reduction was not due the decreased cell growth or increased cellular toxicity and also not due to the induction of hypoxic response. At 3% O(2), the activity of CDK9/cyclin T1 was inhibited and Sp1 activity was reduced, whereas the activity of other host cell factors such as CDK2 or NF-kappaB was not affected. CDK9-specific inhibitor ARC was much less efficient at 3% compared to 21% O(2) and also expression of CDK9/cyclin T1-dependent IkappaB inhibitor alpha was repressed. Our results suggest that lower HIV-1 transcription at 3% O(2) compared to 21% O(2) may be mediated by lower activity of CDK9/cyclin T1 and Sp1 at 3% O(2) and that additional host cell factors such as CDK2 and NF-kappaB might be major regulators of HIV-1 transcription at low O(2) concentrations.
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Affiliation(s)
- Sharroya Charles
- Center for Sickle Cell Disease, Howard University, Washington, DC 20001, USA
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Kim HS, Lim IK. Phosphorylated extracellular signal-regulated protein kinases 1 and 2 phosphorylate Sp1 on serine 59 and regulate cellular senescence via transcription of p21Sdi1/Cip1/Waf1. J Biol Chem 2009; 284:15475-86. [PMID: 19318349 DOI: 10.1074/jbc.m808734200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Expression of p21(Sdi1) downstream of p53 is essential for induction of cellular senescence, although cancer cell senescence can also occur in the p53 null condition. We report herein that senescence-associated phosphorylated extracellular signal-regulated protein kinases 1 and 2 (SA-pErk1/2) enhanced p21(Sdi1) transcription by phosphorylating Sp1 on Ser(59) downstream of protein kinase C (PKC) alpha. Reactive oxygen species (ROS), which was increased in cellular senescence, significantly activated both PKCalpha and PKCbetaI. However, PKCalpha, but not PKCbetaI, regulated ROS generation and cell proliferation in senescent cells along with activation of cdk2, proven by siRNAs. PKCalpha-siRNA also reduced SA-pErk1/2 expression in old human diploid fibroblast cells, accompanied with changes of senescence phenotypes to young cell-like. Regulation of SA-pErk1/2 was also confirmed by using catalytically active PKCalpha and its DN-mutant construct. These findings strongly suggest a new pathway to regulate senescence phenotypes by ROS via Sp1 phosphorylation between PKCalpha and SA-pErk1/2: employing GST-Sp1 mutants and MEK inhibitor analyses, we found that SA-pErk1/2 regulated Sp1 phosphorylation on the Ser(59) residue in vivo, but not threonine, in cellular senescence, which regulated transcription of p21(Sdi1) expression. In summary, PKCalpha, which was activated in senescent cells by ROS strongly activated Erk1/2, and the SA-pErk1/2 in turn phosphorylated Sp1 on Ser(59). Sp1-enhanced transcription of p21(Sdi1) resulted in regulation of cellular senescence in primary human diploid fibroblast cells.
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Affiliation(s)
- Hong Seok Kim
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon 443-721, Korea
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Wang SA, Chuang JY, Yeh SH, Wang YT, Liu YW, Chang WC, Hung JJ. Heat shock protein 90 is important for Sp1 stability during mitosis. J Mol Biol 2009; 387:1106-19. [PMID: 19245816 DOI: 10.1016/j.jmb.2009.02.040] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 01/08/2009] [Accepted: 02/13/2009] [Indexed: 10/21/2022]
Abstract
Our previous study has revealed that heat shock protein (Hsp) 90 can interact with Sp1 to regulate the transcriptional activity of 12(S)-lipoxygenase. Herein, we further found that the interaction between Hsp90 and Sp1 occurred during mitosis. By geldanamycin (GA) treatment and knockdown of Hsp90, we found that this interaction during mitosis was involved in the maintenance of Sp1 stability, and that the phospho-c-Jun N-terminal kinase (JNK)-1 level also decreased. As the JNK-1 was knocked down by the shRNA of JNK-1, Sp1 was degraded through a ubiquitin-dependent proteasome pathway. In addition, for mutation of the JNK-1 phosphorylated residues of Sp1, namely, Sp1(T278/739A) and Sp1(T278/739D), the effect of GA on Sp1 stability was reversed. Finally, based on the involvement of Hsp90 in Sp1 stability, the transcriptional activities of p21(WAF1/CIP1) and 12(S)-lipoxygenase under GA treatment were observed to have decreased. Taken together, Hsp90 is important for maintaining Sp1 stability during mitosis by the JNK-1-mediated phosphorylation of Sp1 to enable division into daughter cells and to regulate the expression of related genes in the interphase.
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Affiliation(s)
- Shao-An Wang
- Institute of Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng-Kung University, Tainan 701, Taiwan
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42
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O-linked N-acetylglucosaminylation of Sp1 inhibits the human immunodeficiency virus type 1 promoter. J Virol 2009; 83:3704-18. [PMID: 19193796 DOI: 10.1128/jvi.01384-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) gene expression and replication are regulated by the promoter/enhancer located in the U3 region of the proviral 5' long terminal repeat (LTR). The binding of cellular transcription factors to specific regulatory sites in the 5' LTR is a key event in the replication cycle of HIV-1. Since transcriptional activity is regulated by the posttranslational modification of transcription factors with the monosaccharide O-linked N-acetyl-D-glucosamine (O-GlcNAc), we evaluated whether increased O-GlcNAcylation affects HIV-1 transcription. In the present study we demonstrate that treatment of HIV-1-infected lymphocytes with the O-GlcNAcylation-enhancing agent glucosamine (GlcN) repressed viral transcription in a dose-dependent manner. Overexpression of O-GlcNAc transferase (OGT), the sole known enzyme catalyzing the addition of O-GlcNAc to proteins, specifically inhibited the activity of the HIV-1 LTR promoter in different T-cell lines and in primary CD4(+) T lymphocytes. Inhibition of HIV-1 LTR activity in infected T cells was most efficient (>95%) when OGT was recombinantly overexpressed prior to infection. O-GlcNAcylation of the transcription factor Sp1 and the presence of Sp1-binding sites in the LTR were found to be crucial for this inhibitory effect. From this study, we conclude that O-GlcNAcylation of Sp1 inhibits the activity of the HIV-1 LTR promoter. Modulation of Sp1 O-GlcNAcylation may play a role in the regulation of HIV-1 latency and activation and links viral replication to the glucose metabolism of the host cell. Hence, the establishment of a metabolic treatment might supplement the repertoire of antiretroviral therapies against AIDS.
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Li B, Wang X, Zhou F, Saunders NA, Frazer IH, Zhao KN. Up-regulated expression of Sp1 protein coincident with a viral protein in human and mouse differentiating keratinocytes may act as a cell differentiation marker. Differentiation 2008; 76:1068-80. [DOI: 10.1111/j.1432-0436.2008.00300.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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44
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Jiang NY, Woda BA, Banner BF, Whalen GF, Dresser KA, Lu D. Sp1, a new biomarker that identifies a subset of aggressive pancreatic ductal adenocarcinoma. Cancer Epidemiol Biomarkers Prev 2008; 17:1648-52. [PMID: 18628415 DOI: 10.1158/1055-9965.epi-07-2791] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pancreatic adenocarcinoma is one of the leading causes of cancer-related deaths in the United States. Sp1 is a sequence-specific DNA binding protein that is important in the transcription of a number of regulatory genes involved in cancer cell growth, differentiation, and metastasis. In this study, we investigated Sp1 expression in pancreatic ductal adenocarcinoma and its association with clinical outcome. We studied 42 patients with primary pancreatic adenocarcinoma. The expression of Sp1 in pancreatic adenocarcinoma was evaluated by immunohistochemical staining. All 42 patients had clinical follow-up information and were evaluated for survival. Sp1 protein was aberrantly overexpressed in a subset of primary pancreatic adenocarcinoma. These tumors all developed metastasis, whereas none of the primary tumors without lymph node metastasis showed Sp1 overexpression. Statistically, Sp1 overexpression was associated with higher stage, higher grade, and lymph node metastasis (P < 0.001, P = 0.036, and P < 0.0001, respectively). Additionally, patients of this subset had a much shorter overall survival than patients without Sp1 overexpression, as evidenced by Kaplan-Meier plots and the log-rank test (P = 0.002). The 5-year overall survival rate was 19% in patients with Sp1 overexpression, compared with 55% in patients without Sp1 overexpression. The median survival was only 13 months for patients with Sp1 overexpression, compared with 65 months for patients without Sp1 overexpression. In conclusion, Sp1 is a new biomarker that identifies a subset of pancreatic ductal adenocarcinoma with aggressive clinical behavior. It can be used at initial diagnosis of pancreatic adenocarcinoma to identify patients with an increased probability of cancer metastasis and much shortened overall survival.
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Affiliation(s)
- Naomi Y Jiang
- Massachusetts Institute of Technology, Cambridge, MA, USA
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Van Duyne R, Kehn-Hall K, Klase Z, Easley R, Heydarian M, Saifuddin M, Wu W, Kashanchi F. Retroviral proteomics and interactomes: intricate balances of cell survival and viral replication. Expert Rev Proteomics 2008; 5:507-28. [PMID: 18532916 DOI: 10.1586/14789450.5.3.507] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Overall changes in the host cellular proteome upon retroviral infection intensify from the initial entry of the virus to the incorporation of viral DNA into the host genome, and finally to the consistent latent state of infection. The host cell reacts to both the entry of viral elements and the manipulation of host cellular machinery, resulting in a cascade of signaling events and pathway activation. Cell type- and tissue-specific responses are also characteristic of infection and can be classified based on the differential expression of genes and proteins between normal and disease states. The characterization of differentially expressed proteins upon infection is also critical in identifying potential biomarkers within infected bodily fluids. Biomarkers can be used to monitor the progression of infection, track the effectiveness of specific treatments and characterize the mechanisms of disease pathogenesis. Standard proteomic approaches have been applied to monitor the changes in global protein expression and localization in infected cells, tissues and fluids. Here we report on recent investigations into the characterization of proteomes in response to retroviral infection.
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Affiliation(s)
- Rachel Van Duyne
- The George Washington University, Department of Microbiology, Immunology, & Tropical Medicine, 2300 I Street, NW, Washington, DC 20037, USA.
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Kim JI, Cordova AC, Hirayama Y, Madri JA, Sumpio BE. Differential effects of shear stress and cyclic strain on Sp1 phosphorylation by protein kinase Czeta modulates membrane type 1-matrix metalloproteinase in endothelial cells. ACTA ACUST UNITED AC 2008; 15:33-42. [PMID: 18568943 DOI: 10.1080/10623320802092260] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Membrane type 1-matrix metalloproteinase (MT1-MMP) plays a key role in extracellular matrix remodeling, endothelial cell (EC) migration, and angiogenesis. Whereas cyclic strain (CS) increases MT1-MMP expression, shear stress (SS) decreases MT1-MMP expression. The aim of this study was to determine if changes in levels of Sp1 phosphorylation induced by protein kinase Czeta (PKCzeta) in ECs exposed to SS but not CS are important for MT1-MMP expression. The results showed that SS increased Sp1 phosphorylation, which could be inhibited by pretreatment with PKCzeta inhibitors. In the presence of PKCzeta inhibitors, the SS-mediated decrease in MT1-MMP protein expression was also abolished. These data demonstrate that increased affinity of Sp1 for MT1-MMP's promoter site occurs as a consequence of PKCzeta-induced phosphorylation of Sp1 in response to SS, increasing Sp1 binding affinity for the promoter site, preventing Egr-1 binding, and consequently decreasing MT1-MMP expression.
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Affiliation(s)
- Ji Il Kim
- Department of Vascular Surgery, Yale University School of Medicine, New Haven, Connecticut, USA
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47
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Liao M, Zhang Y, Dufau ML. Protein kinase Calpha-induced derepression of the human luteinizing hormone receptor gene transcription through ERK-mediated release of HDAC1/Sin3A repressor complex from Sp1 sites. Mol Endocrinol 2008; 22:1449-63. [PMID: 18372343 DOI: 10.1210/me.2008-0035] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
LH receptor (LHR) gene transcription is subject to repression/derepression through various modes and multiple effectors. Epigenetic silencing and activation of the LHR is achieved through coordinated regulation at both histone and DNA levels. The LHR gene is subject to repression by deacetylation and methylation at its promoter region, where a HDAC/mSin3A repressor complex is anchored at Sp1 sites. The present studies revealed that protein kinase C (PKC) alpha/ERK signaling is important for the activation of LHR promoter activity, and the increase of endogenous transcripts induced by phorbol-12-myristate-13-acetate (PMA) in HeLa cells. Whereas these effects were attributable to PKCalpha activity, the ERK pathway was the downstream effector in LHR activation. PMA caused a significant enhancement of Sp1 phosphorylation at serine residue (s), which was blocked by PKCalpha or ERK inhibition. The interaction of activated phosphorylated ERK with Sp1 and ERK's association with the LHR promoter points to Sp1 as a direct target of ERK. After Sp1 phosphorylation, the HDAC1/mSin3A repressor complex dissociated from Sp1 sites, histone 3 was acetylated, and transcription factor II B and RNA polymerase II were recruited. In addition, overexpression of a constitutively active PKCalpha (PKCalpha CA) strongly activated LHR transcription in MCF-7 cells (devoid of PKCalpha), induced Sp1 phosphorylation at serine residue (s) and caused derecruitment of HDAC1/mSin3A complex from the promoter. These effects were negated by cotransfection of a dominant-negative PKCalpha. In conclusion, these studies have revealed a novel regulatory signaling mechanism of transcriptional control in which the LHR is derepressed through PKCalpha/ERK-mediated Sp1 phosphorylation, causing the release of HDAC1/mSin3A complex from the promoter.
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Affiliation(s)
- Mingjuan Liao
- Program in Developmental Endocrinology and Genetics, National Institutes of Health, Bethesda, Maryland 20892-4510, USA
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Tan NY, Midgley VC, Kavurma MM, Santiago FS, Luo X, Peden R, Fahmy RG, Berndt MC, Molloy MP, Khachigian LM. Angiotensin II-inducible platelet-derived growth factor-D transcription requires specific Ser/Thr residues in the second zinc finger region of Sp1. Circ Res 2008; 102:e38-51. [PMID: 18258854 DOI: 10.1161/circresaha.107.167395] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sp1, the first identified and cloned transcription factor, regulates gene expression via multiple mechanisms including direct protein-DNA interactions, protein-protein interactions, chromatin remodeling, and maintenance of methylation-free CpG islands. Sp1 is itself regulated at different levels, for example, by glycosylation, acetylation, and phosphorylation by kinases such as the atypical protein kinase C-zeta. Although Sp1 controls the basal and inducible regulation of many genes, the posttranslational processes regulating its function and their relevance to pathology are not well understood. Here we have used a variety of approaches to identify 3 amino acids (Thr668, Ser670, and Thr681) in the zinc finger domain of Sp1 that are modified by PKC-zeta and have generated novel anti-peptide antibodies recognizing the PKC-zeta-phosphorylated form of Sp1. Angiotensin II, which activates PKC-zeta phosphorylation (at Thr410) via the angiotensin II type 1 receptor, stimulates Sp1 phosphorylation and increases Sp1 binding to the platelet-derived growth factor-D promoter. All 3 residues in Sp1 (Thr668, Ser670, and Thr681) are required for Sp1-dependent platelet-derived growth factor-D activation in response to angiotensin II. Immunohistochemical analysis revealed that phosphorylated Sp1 is expressed in smooth muscle cells of human atherosclerotic plaques and is dynamically expressed together with platelet-derived growth factor-D in smooth muscle cells of the injured rat carotid artery wall. This study provides new insights into the regulatory mechanisms controlling the PKC-zeta-phospho-Sp1 axis and angiotensin II-inducible gene expression.
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Affiliation(s)
- Nicole Y Tan
- Centre for Vascular Research, School of Medical Sciences, University of New South Wales, Sydney, Australia
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Chuang JY, Wang YT, Yeh SH, Liu YW, Chang WC, Hung JJ. Phosphorylation by c-Jun NH2-terminal kinase 1 regulates the stability of transcription factor Sp1 during mitosis. Mol Biol Cell 2008; 19:1139-51. [PMID: 18199680 DOI: 10.1091/mbc.e07-09-0881] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The transcription factor Sp1 is ubiquitously expressed in different cells and thereby regulates the expression of genes involved in many cellular processes. This study reveals that Sp1 was phosphorylated during the mitotic stage in three epithelial tumor cell lines and one glioma cell line. By using different kinase inhibitors, we found that during mitosis in HeLa cells, the c-Jun NH(2)-terminal kinase (JNK) 1 was activated that was then required for the phosphorylation of Sp1. In addition, blockade of the Sp1 phosphorylation via inhibition JNK1 activity in mitosis resulted in the ubiquitination and degradation of Sp1. JNK1 phosphorylated Sp1 at Thr278/739. The Sp1 mutated at Thr278/739 was unstable during mitosis, possessing less transcriptional activity for the 12(S)-lipoxygenase expression and exhibiting a decreased cell growth rate compared with wild-type Sp1 in HeLa cells. In N-methyl-N-nitrosourea-induced mammary tumors, JNK1 activation provided a potential relevance with the accumulation of Sp1. Together, our results indicate that JNK1 activation is necessary to phosphorylate Sp1 and to shield Sp1 from the ubiquitin-dependent degradation pathway during mitosis in tumor cell lines.
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Affiliation(s)
- Jian-Ying Chuang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng-Kung University, Tainan 701, Taiwan
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50
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Klase ZA, Van Duyne R, Kashanchi F. Identification of potential drug targets using genomics and proteomics: a systems approach. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2008; 56:327-68. [PMID: 18086417 DOI: 10.1016/s1054-3589(07)56011-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Zachary A Klase
- Department of Biochemistry, Medical Center, The George Washington University, Washington, DC 20037, USA
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