Expression of the type 1 human immunodeficiency virus Nef protein in T cells prevents antigen receptor-mediated induction of interleukin 2 mRNA.
Stable transformants of the Jurkat T-cell line have been obtained that express either of two distinct forms of the type 1 human immunodeficiency virus nef gene: the nef-1-encoded protein (Nef-1) contains alanine, glycine, and valine at positions 15, 29, and 33, respectively; the protein specified by nef-2 (Nef-2) has threonine, arginine, and alanine at the corresponding positions. When Jurkat cells or their Nef-2-expressing transformants are treated with phorbol 12-myristate 13-acetate (PMA) plus either phytohemagglutinin (PHA) or antibodies against CD3 epsilon, T-cell receptor beta chain, or CD2, there is a prompt increase in interleukin 2 (IL-2) mRNA and intracellular calcium and in the IL-2 receptor alpha chain on the cell surface. Although cells expressing Nef-1 also induce calcium mobilization and the production of IL-2 receptor alpha chain, the formation of IL-2 mRNA is blocked in response to these stimuli. Moreover, Nef-1-expressing cells transfected with a plasmid in which the IL-2 promoter is fused to the chloramphenicol acetyltransferase (CAT) gene fail to induce CAT following treatment with PMA and PHA. By contrast, the parental and Nef-2-containing cells induce CAT normally. Nef-1-expressing cells can produce IL-2 mRNA in response to a combination of PMA and ionomycin, although much less efficiently than the parental Jurkat cells or Nef-2-expressing cells. These findings, and others described herein, suggest that the virally encoded Nef protein interferes with a signal emanating from the T-cell receptor complex that induces IL-2 gene transcription.
Luria
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S
Department of Biochemistry, Beckman Center, Stanford University Medical Center, CA 94305.
Chambers
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I
Berg
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P
D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D005786:Gene Expression Regulation; D015693:Gene Products, nef / Q000235:genetics*; D005814:Genes, Viral; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics*; D015759:Ionomycin / Q000494:pharmacology; D008213:Lymphocyte Activation; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000187:drug effects; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D013601:T-Lymphocytes / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic; D014162:Transfection; D054311:nef Gene Products, Human Immunodeficiency Virus
D015693:Gene Products, nef; D007376:Interleukin-2; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D054311:nef Gene Products, Human Immunodeficiency Virus; D015759:Ionomycin; D015500:Chloramphenicol O-Acetyltransferase; D013755:Tetradecanoylphorbol Acetate