Tat competes with CIITA for the binding to P-TEFb and blocks the expression of MHC class II genes in HIV infection. NLM AIDSLINE Important note: Information in this article was accurate in 2000. The state of the art may have changed since the publication date.

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Tat competes with CIITA for the binding to P-TEFb and blocks the expression of MHC class II genes in HIV infection.

Immunity. 2000 Jan;12(1):61-70. Unique Identifier : AIDSLINE MED/20125022
Kanazawa S; Okamoto T; Peterlin BM; Howard Hughes Medical Institute, Department of Medicine,; University of California, San Francisco 94143, USA.

Abstract: AIDS and the bare lymphocyte syndrome (BLS) are severe combined immunodeficiencies. BLS results from mutations in genes that regulate the expression of class II major histocompatibility (MHC II) determinants. One of these is the class II transactivator (CIITA). HIV and its transcriptional transactivator (Tat) also block the expression of MHC II genes. By binding to the same surface in the cyclin T1, which together with CDK9 forms the positive transcription elongation factor b (P-TEFb) complex, Tat inhibits CIITA. CIITA can also activate transcription when tethered artificially to RNA. Moreover, a dominant-negative CDK9 protein inhibits the activity of MHC II promoters. Thus, CIITA is a novel cellular coactivator that binds to P-TEFb for the expression of its target genes.

Keywords: JOURNAL ARTICLE Animal Antigen Presentation/IMMUNOLOGY B-Lymphocytes/IMMUNOLOGY Cells, Cultured Cyclin-Dependent Kinases/METABOLISM Cyclins/GENETICS/METABOLISM Enterotoxins/IMMUNOLOGY Gene Products, tat/GENETICS/*METABOLISM *Genes, MHC Class II Human HIV Infections/*METABOLISM HIV-1/IMMUNOLOGY HLA-DR Antigens/*GENETICS Promoter Regions (Genetics) Protein-Serine-Threonine Kinases/*METABOLISM Superantigens/IMMUNOLOGY Support, Non-U.S. Gov't Trans-Activation (Genetics) Trans-Activators/GENETICS/*METABOLISMKWDjournalarticleanimalantigenpresentation/immunologyb-lymphocytes/immunologycells,culturedcyclin-dependentkinases/metabolismcyclins/genetics/metabolismenterotoxins/immunologygeneproducts,tat/genetics/KWDmetabolismKWDgenes,mhcclassiihumanhivinfections/KWDmetabolismhiv-1/immunologyhla-drantigens/KWDgeneticspromoterregions(genetics)protein-serine-threoninekinases/KWDmetabolismsuperantigens/immunologysupport,non-uKWDsKWDgov'ttrans-activation(genetics)trans-activators/genetics/KWDmetabolism
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