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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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Multiple Inhibitory Factors Act in the Late Phase of HIV-1 Replication: a Systematic Review of the Literature. Microbiol Mol Biol Rev 2018; 82:82/1/e00051-17. [PMID: 29321222 DOI: 10.1128/mmbr.00051-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The use of lentiviral vectors for therapeutic purposes has shown promising results in clinical trials. The ability to produce a clinical-grade vector at high yields remains a critical issue. One possible obstacle could be cellular factors known to inhibit human immunodeficiency virus (HIV). To date, five HIV restriction factors have been identified, although it is likely that more factors are involved in the complex HIV-cell interaction. Inhibitory factors that have an adverse effect but do not abolish virus production are much less well described. Therefore, a gap exists in the knowledge of inhibitory factors acting late in the HIV life cycle (from transcription to infection of a new cell), which are relevant to the lentiviral vector production process. The objective was to review the HIV literature to identify cellular factors previously implicated as inhibitors of the late stages of lentivirus production. A search for publications was conducted on MEDLINE via the PubMed interface, using the keyword sequence "HIV restriction factor" or "HIV restriction" or "inhibit HIV" or "repress HIV" or "restrict HIV" or "suppress HIV" or "block HIV," with a publication date up to 31 December 2016. Cited papers from the identified records were investigated, and additional database searches were performed. A total of 260 candidate inhibitory factors were identified. These factors have been identified in the literature as having a negative impact on HIV replication. This study identified hundreds of candidate inhibitory factors for which the impact of modulating their expression in lentiviral vector production could be beneficial.
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Ma X, Yang L, Xiao L, Tang M, Liu L, Li Z, Deng M, Sun L, Cao Y. Down-regulation of EBV-LMP1 radio-sensitizes nasal pharyngeal carcinoma cells via NF-κB regulated ATM expression. PLoS One 2011; 6:e24647. [PMID: 22096476 PMCID: PMC3212510 DOI: 10.1371/journal.pone.0024647] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 08/16/2011] [Indexed: 02/06/2023] Open
Abstract
Background The latent membrane protein 1 (LMP1) encoded by EBV is expressed in the majority of EBV-associated human malignancies and has been suggested to be one of the major oncogenic factors in EBV-mediated carcinogenesis. In previous studies we experimentally demonstrated that down-regulation of LMP1 expression by DNAzymes could increase radiosensitivity both in cells and in a xenograft NPC model in mice. Results In this study we explored the molecular mechanisms underlying the radiosensitization caused by the down-regulation of LMP1 in nasopharyngeal carcinoma. It was confirmed that LMP1 could up-regulate ATM expression in NPCs. Bioinformatic analysis of the ATM ptomoter region revealed three tentative binding sites for NF-κB. By using a specific inhibitor of NF-κB signaling and the dominant negative mutant of IkappaB, it was shown that the ATM expression in CNE1-LMP1 cells could be efficiently suppressed. Inhibition of LMP1 expression by the DNAzyme led to attenuation of the NF-κB DNA binding activity. We further showed that the silence of ATM expression by ATM-targeted siRNA could enhance the radiosensitivity in LMP1 positive NPC cells. Conclusions Together, our results indicate that ATM expression can be regulated by LMP1 via the NF-κB pathways through direct promoter binding, which resulted in the change of radiosensitivity in NPCs.
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Affiliation(s)
- Xiaoqian Ma
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, China
| | - Lifang Yang
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, China
- Center for Molecular Medicine, Central South University, Xiangya Hospital, Changsha, China
| | - Lanbo Xiao
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, China
| | - Min Tang
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, China
| | - Liyu Liu
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, China
| | - Zijian Li
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, China
| | - Mengyao Deng
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, China
| | - Lunquan Sun
- Center for Molecular Medicine, Central South University, Xiangya Hospital, Changsha, China
- Center for Molecular Imaging, Central South University, Changsha, China
- * E-mail: (LQS); (YC)
| | - Ya Cao
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, China
- Key Laboratory of Carcinogenesis and Invasion, Ministry of Education, Key Laboratory of Carcinogenesis, Ministry of Health, Changsha, China
- Center for Molecular Imaging, Central South University, Changsha, China
- * E-mail: (LQS); (YC)
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4
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Gutierrez-Sanmartin D, Varela-Ledo E, Aguilera A, Romero-Yuste S, Romero-Jung P, Gomez-Tato A, Regueiro BJ. Implication of p38 mitogen-activated protein kinase isoforms (alpha, beta, gamma and delta) in CD4+ T-cell infection with human immunodeficiency virus type I. J Gen Virol 2008; 89:1661-1671. [PMID: 18559936 DOI: 10.1099/vir.0.82971-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The CD4(+) T-cell reduction characteristic of human immunodeficiency virus type 1 (HIV-1) infection is thought to result, in addition to infected T-cell death, mainly from uninfected bystander T-cell apoptosis. Nevertheless, the immunological and virological mechanisms leading to T-cell death during HIV-1 infection are not yet fully understood. In the present study, we analysed the individual implication of the p38 mitogen-activated protein kinase (MAPK) isoforms (p38alpha, p38beta, p38gamma and p38delta) during apoptosis induced by HIV-1, taking into account that HIV-1 replication is known to be blocked by p38 inhibitors. For this purpose, we used the SupT1 cell line, where death induced by HIV-1 mainly occurs by uninfected bystander cell apoptosis. A variety of SupT1-based cell lines were constructed constitutively expressing, under the control of cytomegalovirus promoter (PCMV), each dominant-negative (dn) p38 isoform and each wild-type p38 isoform as a control. An enhanced green fluorescent protein marker gene, under the control of the HIV-1 promoter, was inserted in all of them. These cell lines were infected with HIV-1 and analysed by flow cytometry. We found that survival in SupT1-based cell lines infected by HIV-1 was increased by the p38alphadn, p38gammadn and p38deltadn isoforms, but not by the p38betadn isoform. HIV-1 replication was delayed most by p38deltadn and to a lesser extent by p38alphadn and p38gammadn. Moreover, these three isoforms, p38alphadn, p38gammadn and p38deltadn, reduced apoptosis induced by HIV-1. These results suggest that, in SupT1-based cell lines, p38alpha, p38gamma and p38delta, but not p38beta, are implicated in both HIV-1 induced replication and apoptosis in infected and uninfected bystander cells.
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Affiliation(s)
- Dolores Gutierrez-Sanmartin
- Clinical Microbiology, Hospital de Conxo, Complejo Hospitalario Universitario de Santiago (CHUS), 15706 Santiago de Compostela, Spain
| | - Eduardo Varela-Ledo
- Clinical Microbiology, Hospital de Conxo, Complejo Hospitalario Universitario de Santiago (CHUS), 15706 Santiago de Compostela, Spain
| | - Antonio Aguilera
- Clinical Microbiology, Hospital de Conxo, Complejo Hospitalario Universitario de Santiago (CHUS), 15706 Santiago de Compostela, Spain
| | - Susana Romero-Yuste
- Rheumatology, Hospital Provincial, Complejo Hospitalario de Pontevedra (CHOP), Pontevedra, Spain
| | - Patricia Romero-Jung
- Clinical Microbiology, Hospital de Conxo, Complejo Hospitalario Universitario de Santiago (CHUS), 15706 Santiago de Compostela, Spain
| | - Antonio Gomez-Tato
- Facultad de Matematicas, Universidad de Santiago (Campus Sur), Santiago de Compostela, Spain
| | - Benito J Regueiro
- Clinical Microbiology, Hospital de Conxo, Complejo Hospitalario Universitario de Santiago (CHUS), 15706 Santiago de Compostela, Spain
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5
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Abstract
Nuclear factor (NF)-kappaB and inhibitor of NF-kappaB kinase (IKK) proteins regulate many physiological processes, including the innate- and adaptive-immune responses, cell death and inflammation. Disruption of NF-kappaB or IKK function contributes to many human diseases, including cancer. However, the NF-kappaB and IKK pathways do not exist in isolation and there are many mechanisms that integrate their activity with other cell-signalling networks. This crosstalk constitutes a decision-making process that determines the consequences of NF-kappaB and IKK activation and, ultimately, cell fate.
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Affiliation(s)
- Neil D Perkins
- College of Life Sciences, Division of Gene Regulation and Expression, James Black Centre, Dow Street, University of Dundee, Dundee, DD1 5EH, Scotland, UK.
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6
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Liu HD, Zheng H, Li M, Hu DS, Tang M, Cao Y. Upregulated expression of kappa light chain by Epstein-Barr virus encoded latent membrane protein 1 in nasopharyngeal carcinoma cells via NF-kappaB and AP-1 pathways. Cell Signal 2006; 19:419-27. [PMID: 16979873 DOI: 10.1016/j.cellsig.2006.07.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Accepted: 07/24/2006] [Indexed: 12/13/2022]
Abstract
B lymphocytes are generally considered to be the only source of immunoglobulins. However, increasing evidence revealed that some human epithelial cancer cell lines, including nasopharyngeal carcinoma (NPC) cell lines, expressed immunoglobulins. Moreover, we previously found that expression of kappa light chain in NPC cells could be upregulated by EBV-encoded latent membrane protein 1 (LMP1). Here, Western blot and flow cytometric analysis of intracellular kappa staining indicated that upregulation of the expression of kappa was inhibited by using LMP1-targeted DNAzyme and that Bay11-7082 and SP600125, inhibitors of JNK and NF-kappaB, respectively, inhibited LMP1-augmented kappa light chain expression in NPC cells. LMP1-positive NPC cells expressing the dominant-negative mutant of IkappaBalpha (DNMIkappaBalpha) or of c-Jun (TAM67) exhibited significantly decreasing kappa production compared with their parental cells. These results suggest that LMP1 elevated kappa light chain through activation of the NF-kappaB and AP-1 signaling pathways. The present study provided some hints of possible mechanisms by which human cancer cells of epithelial origin produced immunoglobulins.
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Affiliation(s)
- Hai-dan Liu
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Xiangya Road #110, Changsha, Hunan 410078, PR China
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7
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Ganesh L, Yoshimoto T, Moorthy NC, Akahata W, Boehm M, Nabel EG, Nabel GJ. Protein methyltransferase 2 inhibits NF-kappaB function and promotes apoptosis. Mol Cell Biol 2006; 26:3864-74. [PMID: 16648481 PMCID: PMC1488990 DOI: 10.1128/mcb.26.10.3864-3874.2006] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 12/18/2005] [Accepted: 02/18/2006] [Indexed: 11/20/2022] Open
Abstract
The protein arginine methyltransferases (PRMTs) include a family of proteins with related putative methyltransferase domains that modify chromatin and regulate cellular transcription. Although some family members, PRMT1 and PRMT4, have been implicated in transcriptional modulation or intracellular signaling, the roles of other PRMTs in diverse cellular processes have not been fully established. Here, we report that PRMT2 inhibits NF-kappaB-dependent transcription and promotes apoptosis. PRMT2 exerted this effect by blocking nuclear export of IkappaB-alpha through a leptomycin-sensitive pathway, increasing nuclear IkappaB-alpha and decreasing NF-kappaB DNA binding. The highly conserved S-adenosylmethionine-binding domain of PRMT2 mediated this effect. PRMT2 also rendered cells susceptible to apoptosis by cytokines or cytotoxic drugs, likely due to its effects on NF-kappaB. Mouse embryo fibroblasts from PRMT2 genetic knockouts showed elevated NF-kappaB activity and decreased susceptibility to apoptosis compared to wild-type or complemented cells. Taken together, these data suggest that PRMT2 inhibits cell activation and promotes programmed cell death through this NF-kappaB-dependent mechanism.
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Affiliation(s)
- Lakshmanan Ganesh
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 40, Room 4502, 40 Convent Dr., Bethesda, Maryland 20892-3005, USA
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8
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Abstract
A role for the NF-kappaB family of transcription factors as tumor promoters is firmly established. However, other data suggest that NF-kappaB can also inhibit tumor growth. Moreover, NF-kappaB activity is modulated by tumor suppressors, such as p53 and ARF, whereby NF-kappaB subunits repress, rather than activate, the expression of tumor-promoting genes. This suggests a dual function of NF-kappaB during tumor progression - in the early stages, NF-kappaB inhibits tumor growth but, as further mutations lead to a loss of tumor suppressor expression, the oncogenic functions of NF-kappaB become unleashed, allowing it to actively contribute to tumorigenesis. Here, I discuss this hypothesis, its implications for NF-kappaB function, and how this might influence the use of NF-kappaB-based anticancer therapies.
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Affiliation(s)
- Neil D Perkins
- Division of Gene Regulation and Expression, School of Life Sciences, MSI/WTB Complex, Dow Street, University of Dundee, Dundee, UK DD1 5EH.
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9
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Tao YG, Tan YN, Liu YP, Song X, Zeng L, Gu HH, Tang M, Li W, Yi W, Cao Y. Epstein-Barr virus latent membrane protein 1 modulates epidermal growth factor receptor promoter activity in a nuclear factor kappa B-dependent manner. Cell Signal 2004; 16:781-90. [PMID: 15115657 DOI: 10.1016/j.cellsig.2003.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Revised: 12/01/2003] [Accepted: 12/02/2003] [Indexed: 11/24/2022]
Abstract
The Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) oncoprotein may cause multiple cellular changes including the induction of epidermal growth factor receptor (EGFR) expression and activation of the NFkappaB transcription factor. LMP1 increases the levels of both EGFR protein and mRNA, but does not stabilize EGFR mRNA. Thus, the effects of LMP1 are likely to be mediated by the direct activation of the EGFR promoter. In this study, induction of LMP1 increased the EGFR in both protein and promoter levels in a dose-dependent manner using tetracycline-regulated LMP1 expression in nasopharyngeal carcinoma (NPC) cell line. Mutational analysis of the LMP1 protein indicated that the C-terminal activation region-1 (CTAR1) domain was mainly involved in the EGFR promoter induction, while CTAR2 was necessary but not sufficient to induce EGFR promoter. Inhibition of LMP1-mediated NFkappaB activation by constitutive repressive IkappaBalpha marginally decreased EGFR promoter activity using transiently transfected IkappaBalpha dominant negative mutant. Promoter mutagenesis analysis demonstrated that two putative NFkappaB binding sites of EGFR promoter were very necessary for the transcriptional activity of EGFR induced by LMP1, the proximal NFkappaB binding site was more important than the distal NFkappaB binding site, and both NFkappaB binding sites played a cooperative role. Taken together, Epstein-Barr virus latent membrane protein 1 modulated the EGFR promoter activity in a NFkappaB-dependent manner.
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Affiliation(s)
- Yong-Guang Tao
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, 410078, Hunan, PR China
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10
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Cheng H, Cenciarelli C, Tao M, Parks WP, Cheng-Mayer C. HTLV-1 Tax-associated hTid-1, a human DnaJ protein, is a repressor of Ikappa B kinase beta subunit. J Biol Chem 2002; 277:20605-10. [PMID: 11927590 DOI: 10.1074/jbc.m201204200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
hTid-1, a human DnaJ protein, is a novel cellular target for HTLV-1 Tax. Here, we show that hTid-1 represses NF-kappaB activity induced by Tax as well as other activators such as tumor necrosis factor alpha (TNFalpha) and Bcl10. hTid-1 specifically suppresses serine phosphorylation of IkappaBalpha by activated IkappaB kinase beta (IKKbeta), but the activities of other serine kinases including p38, ERK2, and JNK1 are not affected. The suppressive activity of hTid-1 on IKKbeta requires a functional J domain that mediates association with heat shock proteins and results in prolonging the half-life of the NF-kappaB inhibitors IkappaBalpha and IkappaBbeta. Collectively, our data suggest that hTid-1, in association with heat shock proteins, exerts a negative regulatory effect on the NF-kappaB activity induced by various extracellular and intracellular activators including HTLV-1 Tax.
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Affiliation(s)
- Hua Cheng
- Aaron Diamond AIDS Research Center, Rockefeller University, New York, New York 10021, USA.
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11
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Asin S, Bren GD, Carmona EM, Solan NJ, Paya CV. NF-kappaB cis-acting motifs of the human immunodeficiency virus (HIV) long terminal repeat regulate HIV transcription in human macrophages. J Virol 2001; 75:11408-16. [PMID: 11689622 PMCID: PMC114727 DOI: 10.1128/jvi.75.23.11408-11416.2001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The role of NF-kappaB in the reactivation of human immunodeficiency virus (HIV) from latency in CD4 T lymphocytes is well documented. However, its role in driving HIV transcription in human macrophages, which contain a constitutive nuclear pool of NF-kappaB, is less well understood. In this study we have investigated the role that the constitutive pool of NF-kappaB and the NF-kappaB cis-acting motifs of the HIV long terminal repeat (LTR) play in regulating HIV transcription in human monocytic cells and primary macrophages. Inhibition of the constitutive nuclear pool of NF-kappaB (RelA and RelB) in the promonocytic U937 cell line using dominant-negative IkappaBalpha significantly decreases HIV replication. Moreover, it is demonstrated that in the differentiated monocytic cell line THP1, which contains a constitutive nuclear pool of NF-kappaB (RelB),an HIV provirus containing mutations of the kappaB cis-acting sites in the LTR is transcriptionally impaired. Reduction of the constitutive pool of NF-kappaB in human macrophages by an adenovirus vector expressing a dominant-negative IkappaBalpha also reduces HIV transcription. Lastly, mutation of the NF-kappaB cis-acting sites in the LTR of an R5 HIV provirus completely abrogates the first cycle of HIV transcription. These studies indicate that the cis-acting NF-kappaB motifs of the HIV LTR are critical in initiating HIV transcription in human macrophages and suggest that the constitutive nuclear pool of NF-kappaB is important in regulating HIV transcription in these cells.
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Affiliation(s)
- S Asin
- Department of Immunology, Mayo Clinic, Rochester, Minnesota 55905, USA
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12
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Rabson AB, Lin HC. NF-kappa B and HIV: linking viral and immune activation. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2001; 48:161-207. [PMID: 10987091 DOI: 10.1016/s1054-3589(00)48006-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- A B Rabson
- Department of Molecular Genetics and Microbiology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854, USA
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13
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Dayton AI, Zhang MJ. Therapies directed against the Rev axis of HIV autoregulation. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2001; 49:199-228. [PMID: 11013765 DOI: 10.1016/s1054-3589(00)49028-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- A I Dayton
- Laboratory of Molecular Virology, Food and Drug Administration, Rockville, Maryland 20852-1448, USA
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14
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Abstract
Induction of transcription from the human immunodeficiency virus 1 long terminal repeat by the RelA (p65) NF-kappaB subunit has been shown to be dependent upon an interaction with the zinc finger DNA-binding domain of Sp1. It was unknown, however, whether NF-kappaB could also interact with other zinc finger-containing transcription factors. In this study we demonstrate that the early growth response transcription factor Egr-1, whose DNA-binding domain shares a high degree of homology with that of Sp1, can also interact with RelA in vitro and regulate NF-kappaB transcriptional activity in vivo. Similar to the interaction with Sp1, the Rel homology domain of RelA interacts with the zinc finger domain of Egr-1. Surprisingly, and in contrast to Sp1, Egr-1 specifically represses RelA transcriptional activity through its zinc finger domain. Moreover, the interaction between RelA and the Egr-1 zinc fingers is mutually exclusive with DNA binding suggesting a model in which Egr-1 directly sequesters NF-kappaB from its target promoters. Because Egr-1 is induced by many of the same stimuli that activate NF-kappaB, this novel transcriptional regulatory mechanism has many implications for the involvement of both factors in cellular processes such as apoptosis and the response to stress and infection.
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Affiliation(s)
- N R Chapman
- Department of Biochemistry, Division of Gene Expression and Regulation, MSI/WTB Complex, Dow Street, University of Dundee, Dundee, DD1 5EH Scotland, United Kingdom
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15
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Kjems J, Askjaer P. Rev protein and its cellular partners. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2000; 48:251-98. [PMID: 10987094 DOI: 10.1016/s1054-3589(00)48009-9] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- J Kjems
- Department of Molecular and Structural Biology, University of Aarhus, Denmark
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16
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Webster GA, Perkins ND. Transcriptional cross talk between NF-kappaB and p53. Mol Cell Biol 1999; 19:3485-95. [PMID: 10207072 PMCID: PMC84141 DOI: 10.1128/mcb.19.5.3485] [Citation(s) in RCA: 474] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/1998] [Accepted: 02/12/1999] [Indexed: 11/20/2022] Open
Abstract
Many cellular stimuli result in the induction of both the tumor suppressor p53 and NF-kappaB. In contrast to activation of p53, which is associated with the induction of apoptosis, stimulation of NF-kappaB has been shown to promote resistance to programmed cell death. These observations suggest that a regulatory mechanism must exist to integrate these opposing outcomes and coordinate this critical cellular decision-making event. Here we show that both p53 and NF-kappaB inhibit each other's ability to stimulate gene expression and that this process is controlled by the relative levels of each transcription factor. Expression of either wild-type p53 or the RelA(p65) NF-kappaB subunit suppresses stimulation of transcription by the other factor from a reporter plasmid in vivo. Moreover, endogenous, tumor necrosis factor alpha-activated NF-kappaB will inhibit endogenous wild-type p53 transactivation. Following exposure to UV light, however, the converse is observed, with p53 downregulating NF-kappaB-mediated transcriptional activation. Both p53 and RelA(p65) interact with the transcriptional coactivator proteins p300 and CREB-binding protein (CBP), and we demonstrate that these results are consistent with competition for a limiting pool of p300/CBP complexes in vivo. These observations have many implications for regulation of the transcriptional decision-making mechanisms that govern cellular processes such as apoptosis. Furthermore, they suggest a previously unrealized mechanism through which dysregulated NF-kappaB can contribute to tumorigenesis and disease.
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Affiliation(s)
- G A Webster
- Department of Biochemistry, Division of Gene Regulation and Expression, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
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17
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Asin S, Taylor JA, Trushin S, Bren G, Paya CV. Ikappakappa mediates NF-kappaB activation in human immunodeficiency virus-infected cells. J Virol 1999; 73:3893-903. [PMID: 10196284 PMCID: PMC104167 DOI: 10.1128/jvi.73.5.3893-3903.1999] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human monocytes and macrophages are persistent reservoirs of human immunodeficiency virus (HIV) type-1. Persistent HIV infection of these cells results in increased levels of NF-kappaB in the nucleus secondary to increased IkappaBalpha, IkappaBbeta, and IkappaBepsilon degradation, a mechanism postulated to regulate viral persistence. To characterize the molecular mechanisms regulating HIV-mediated degradation of IkappaB, we have sought to identify the regulatory domains of IkappaBalpha targeted by HIV infection. Using monocytic cells stably expressing different transdominant molecules of IkappaBalpha, we determined that persistent HIV infection of these cells targets the NH2 but not the COOH terminus of IkappaBalpha. Further analysis demonstrated that phosphorylation at S32 and S36 is necessary for HIV-dependent IkappaBalpha degradation and NF-kappaB activation. Of the putative N-terminal IkappaBalpha kinases, we demonstrated that the Ikappakappa complex, but not p90(rsk), is activated by HIV infection and mediates HIV-dependent NF-kappaB activation. Analysis of viral replication in cells that constitutively express IkappaBalpha negative transdominant molecules demonstrated a lack of correlation between virus-induced NF-kappaB (p65/p50) nuclear translocation and degree of viral persistence in human monocytes.
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Affiliation(s)
- S Asin
- Department of Immunology, Mayo Clinic, Rochester, Minnesota 55905, USA
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18
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Wang CY, Mayo MW, Korneluk RG, Goeddel DV, Baldwin AS. NF-kappaB antiapoptosis: induction of TRAF1 and TRAF2 and c-IAP1 and c-IAP2 to suppress caspase-8 activation. Science 1998; 281:1680-3. [PMID: 9733516 DOI: 10.1126/science.281.5383.1680] [Citation(s) in RCA: 2154] [Impact Index Per Article: 82.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Tumor necrosis factor alpha (TNF-alpha) binding to the TNF receptor (TNFR) potentially initiates apoptosis and activates the transcription factor nuclear factor kappa B (NF-kappaB), which suppresses apoptosis by an unknown mechanism. The activation of NF-kappaB was found to block the activation of caspase-8. TRAF1 (TNFR-associated factor 1), TRAF2, and the inhibitor-of-apoptosis (IAP) proteins c-IAP1 and c-IAP2 were identified as gene targets of NF-kappaB transcriptional activity. In cells in which NF-kappaB was inactive, all of these proteins were required to fully suppress TNF-induced apoptosis, whereas c-IAP1 and c-IAP2 were sufficient to suppress etoposide-induced apoptosis. Thus, NF-kappaB activates a group of gene products that function cooperatively at the earliest checkpoint to suppress TNF-alpha-mediated apoptosis and that function more distally to suppress genotoxic agent-mediated apoptosis.
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Affiliation(s)
- C Y Wang
- Department of Endodontics, School of Dentistry, Lineberger Comprehensive Cancer Center, and Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599-7295, USA
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19
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Latimer M, Ernst MK, Dunn LL, Drutskaya M, Rice NR. The N-terminal domain of IkappaB alpha masks the nuclear localization signal(s) of p50 and c-Rel homodimers. Mol Cell Biol 1998; 18:2640-9. [PMID: 9566883 PMCID: PMC110643 DOI: 10.1128/mcb.18.5.2640] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Members of the Rel/NF-kappaB family of transcription factors are related to each other over a region of about 300 amino acids called the Rel Homology Domain (RHD), which governs DNA binding, dimerization, and binding to inhibitor. At the C-terminal end of the RHD, each protein has a nuclear localization signal (NLS). The crystal structures of the p50 and RelA family members show that the RHD consists of two regions: an N-terminal section which contains some of the DNA contacts and a C-terminal section which contains the remaining DNA contacts and controls dimerization. In unstimulated cells, the homo- or heterodimeric Rel/NF-kappaB proteins are cytoplasmic by virtue of binding to an inhibitor protein (IkappaB) which somehow masks the NLS of each member of the dimer. The IkappaB proteins consist of an ankyrin-repeat-containing domain that is required for binding to dimers and N- and C-terminal domains that are dispensable for binding to most dimers. In this study, we examined the interaction between IkappaB alpha and Rel family homodimers by mutational analysis. We show that (i) the dimerization regions of p50, RelA, and c-Rel are sufficient for binding to IkappaB alpha, (ii) the NLSs of RelA and c-Rel are not required for binding to IkappaB alpha but do stabilize the interaction, (iii) the NLS of p50 is required for binding to IkappaB alpha, (iv) only certain residues within the p50 NLS are required for binding, and (v) in a p50-IkappaB alpha complex or a c-Rel-IkappaB alpha complex, the N terminus of IkappaB alpha either directly or indirectly masks one or both of the dimer NLSs.
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Affiliation(s)
- M Latimer
- Molecular Basis of Carcinogenesis Laboratory, ABL-Basic Research Program, National Cancer Institute-Frederick Cancer Research and Development Center, Maryland 21701, USA
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DeLuca C, Kwon H, Pelletier N, Wainberg MA, Hiscott J. NF-kappaB protects HIV-1-infected myeloid cells from apoptosis. Virology 1998; 244:27-38. [PMID: 9581775 DOI: 10.1006/viro.1998.9085] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
HIV-1 infection of primary monocytic cells and myeloid cell lines results in sustained NF-kappaB activation. Recently, NF-kappaB induction has been shown to play a role in protecting cells from programmed cell death. In the present study, we sought to investigate whether constitutive NF-kappaB activity in chronically HIV-1-infected promonocytic U937 (U9-IIIB) and myeloblastic PLB-985 (PLB-IIIB) cells affects apoptotic signaling. TNFalpha and cycloheximide caused infected cells to undergo apoptosis more rapidly than parental U937 and PLB-985 cells. Inhibition of TNFalpha-induced NF-kappaB activation using the antioxidant N-acetylcysteine (NAC) resulted in increased apoptosis in both U937 and U9-IIIB cells, while preactivation of NF-kappaB with the non-apoptotic inducer IL-1beta caused a relative decrease in apoptosis. Inhibition of constitutive NF-kappaB activity in U9-IIIB and PLB-IIIB cells also induced apoptosis, suggesting that NF-kappaB protects cells from a persistent apoptotic signal. TNFalpha plus NAC treatment resulted in a marked decrease in Bcl-2 protein levels in HIV-1-infected cells, coupled with an increase in Bax protein compared to uninfected cells, suggesting that the difference in susceptibility to TNFalpha-induced apoptosis may relate to the differences in relative levels of Bcl-2 and Bax. The protective role of NF-kappaB in blocking TNFalpha- and HIV-1-induced apoptosis was supported by studies in Jurkat T cells engineered to express IkappaB alpha repressor mutants (TD-IkappaB) under the control of a tetracycline-responsive promoter. Cells underwent apoptosis in response to TNFalpha only when NF-kappaB activation was inhibited by TD-IkappaB expression. As was observed for the U9-IIIB cells, TNFalpha treatment also induced a marked decrease in Bcl-2 protein levels in TD-IkappaB expressing cells. These experiments demonstrate that apoptotic signaling is perturbed in HIV-1-infected U9-IIIB cells and indicate that NF-kappaB activation may play an additional protective role against HIV-1-induced apoptosis in myeloid cells.
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Affiliation(s)
- C DeLuca
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Department of Medicine, McGill University, Montreal, Quebec, Canada
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21
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Kwon H, Pelletier N, DeLuca C, Genin P, Cisternas S, Lin R, Wainberg MA, Hiscott J. Inducible expression of IkappaBalpha repressor mutants interferes with NF-kappaB activity and HIV-1 replication in Jurkat T cells. J Biol Chem 1998; 273:7431-40. [PMID: 9516441 DOI: 10.1074/jbc.273.13.7431] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human immunodeficiency virus (HIV-1) utilizes the NF-kappaB/Rel proteins to regulate transcription through NF-kappaB binding sites in the HIV-1 long terminal repeat (LTR). Normally, NF-kappaB is retained in the cytoplasm by inhibitory IkappaB proteins; after stimulation by multiple activators including viruses, IkappaBalpha is phosphorylated and degraded, resulting in NF-kappaB release. In the present study, we examined the effect of tetracycline-inducible expression of transdominant repressors of IkappaBalpha (TD-IkappaBalpha) on HIV-1 multiplication using stably selected Jurkat T cells. TD-IkappaBalpha was inducibly expressed as early as 3 h after doxycycline addition and dramatically reduced both NF-kappaB DNA binding activity and LTR-directed gene activity. Interestingly, induced TD-IkappaBalpha expression also decreased endogenous IkappaBalpha expression to undetectable levels by 24 h after induction, demonstrating that TD-IkappaBalpha repressed endogenous NF-kappaB-dependent gene transcription. TD-IkappaBalpha expression also sensitized Jurkat cells to tumor necrosis factor-induced apoptosis. De novo HIV-1 infection of Jurkat cells was dramatically altered by TD-IkappaBalpha induction, resulting in inhibition of HIV-1 multiplication, as measured by p24 antigen, reverse transcriptase, and viral RNA. Given the multiple functions of the NF-kappaB/IkappaB pathway, TD-IkappaBalpha expression may interfere with HIV-1 multiplication at several levels: LTR-mediated transcription, Rev-mediated export of viral RNA, inhibition of HIV-1-induced pro-inflammatory cytokines, and increased sensitivity of HIV-1-infected cells to apoptosis.
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Affiliation(s)
- H Kwon
- Lady Davis Institute for Medical Research, McGill University, Montreal, Quebec H3T 1E2, Canada
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Roth J, Dobbelstein M. Export of hepatitis B virus RNA on a Rev-like pathway: inhibition by the regenerating liver inhibitory factor IkappaB alpha. J Virol 1997; 71:8933-9. [PMID: 9343262 PMCID: PMC192368 DOI: 10.1128/jvi.71.11.8933-8939.1997] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Nuclear export of hepatitis B virus (HBV) RNA is mediated by a specific RNA element but, in contrast to lentivirus genomic RNA, does not depend on viral proteins. We show that nonetheless, the export of HBV RNA can be blocked by competitive inhibitors of Rev-mediated lentivirus RNA export, suggesting that the export pathways of both viral species share components and might be driven by the same nuclear export machinery. HBV RNA export is also inhibited by overexpression of IkappaB alpha, as reported previously for the export of human immunodeficiency virus RNA. Since IkappaB alpha is strongly overexpressed during liver regeneration, its inhibition of HBV RNA export might contribute to elimination or silent persistence of HBV.
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Affiliation(s)
- J Roth
- ZIM, Gastroenterologie, Klinikum der Universität Marburg, Germany
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