NFAT1 enhances HIV-1 gene expression in primary human CD4 T cells.
Cyclosporin A (CsA) is a potent inhibitor of the NFAT family of transcription factors that enhance T cell activation. The observation that human immunodeficiency virus type 1 (HIV-1)-positive transplant recipients have a reduced HIV-1 viral burden during treatment with CsA suggested that NFAT may play a direct role in enhancing transcription of the HIV-1 viral genome. Two sets of NFAT binding sites were identified in the HIV-1 long terminal repeat (LTR) promoter by in vitro footprinting with full-length recombinant NFAT protein, and gel shift analysis of nuclear protein from polyclonally activated primary CD4 T cells revealed specific binding of NFAT1 to the NFkappaB binding sites of the HIV-1 LTR. Activation of primary CD4 T cells transiently transfected with a HIV-1 LTR luciferase reporter plasmid, lacking the NFAT binding sites in the upstream putative negative regulatory element but maintaining the NFkappaB/NFAT sites, demonstrated increased HIV-1 gene expression when cotransfected with a NFAT1 expression vector. Moreover, CsA, FK506, and a dominant-negative NFAT1 protein independently inhibited HIV-1 LTR promoter activity in CD4 T cells stimulated with phorbol ester and calcium ionophore. In primary human CD4 T cells, CsA also inhibited promoter activity directed by multimers of binding sites for NFAT, while having no effect on NFkappaB multimer-driven promoter activity. Increasing NFAT1 levels in CD4 T cells transiently transfected with a HIV-1 provirus also increased p24 protein expression. Thus, NFAT may be a target for prevention of HIV-1 LTR-directed gene expression in human CD4 T cells.
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Division of Immunology and Transplantation Biology, Stanford University Medical Center, Palo Alto, California 94304-5208, USA.
Bartz
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Clausell
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A
Bort
S J
SJ
Klebanoff
S J
SJ
Lewis
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D001665:Binding Sites; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism* / Q000821:virology; D016572:Cyclosporine / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D016655:HIV Core Protein p24 / Q000235:genetics; D016325:HIV Long Terminal Repeat / Q000187:drug effects; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*
D004268:DNA-Binding Proteins; D016655:HIV Core Protein p24; D016328:NF-kappa B; D050778:NFATC Transcription Factors; C494006:NFATC2 protein, human; D009687:Nuclear Proteins; D014157:Transcription Factors; D016572:Cyclosporine