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      The expression of the interleukin 6 gene is induced by the human immunodeficiency virus 1 TAT protein

      research-article
      The Journal of Experimental Medicine
      The Rockefeller University Press

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          Abstract

          Human immunodeficiency virus 1 (HIV1) infection is associated with severe psoriasis, B cell lymphoma, and Kaposi's sarcoma. A deregulated production of interleukin 6 (IL-6) has been implicated in the pathogenesis of these diseases. The molecular mechanisms underlying the abnormal IL-6 secretion of HIV1-infected cells may include transactivation of the IL-6 gene by HIV1. To test this hypothesis, we used the pIL6Pr-chloramphenicol acetyltransferase (CAT) plasmid, an IL- 6 promoter-CAT construct, as a target of the transactivating function of the HIV1 TAT protein. By cotransfecting the pIL6Pr-CAT and the tat- expressing pSVT8 plasmid in MC3 B-lymphoblastoid or in HeLa epithelial cells, we observed that TAT transactivates the human IL-6 promoter. These results were confirmed when pIL6Pr-CAT was transfected in MC3 or HeLa cells that constitutively expressed the tat gene in a sense (pSVT8 cells) or antisense (pSVT10 cells) orientation. 5' deletion plasmids of pIL6Pr-CAT, in which regions at -658, -287, and -172 were inserted 5' to the cat gene, were transiently transfected in pSVT10 and pSVT8 cells and showed that TAT-induced activation of the IL-6 promoter required a minimal region located between -287 and -54 bp. Moreover, experiments with plasmids carrying the -658, -287, and -172 bp regions of the IL-6 promoter inserted downstream to a TAR-deleted HIV1-LTR identified the sequence of -172 to -54 as the minimal region of the IL-6 promoter required for TAT to transactivate the TAR-deleted HIV1-LTR. By DNA- protein binding experiments, tat-transfected cells expressed a consistent increase in kappa B and nuclear factor (NF)-IL-6 binding activity. Accordingly, the pDRCAT and IL-1REK9CAT, carrying tandem repeats of NF-kappa B or NF-IL6 binding motifs, respectively, were activated in TAT-expressing cells. The biological relevance of the TAT- induced IL-6 secretion was addressed by generating 7TD1 cells, an IL-6- dependent mouse cell line, stably expressing the tat gene. These tat- positive cells expressed the endogenous IL-6 gene, secreted high amounts of murine IL-6, and grew efficiently in the absence of exogenous IL-6. Moreover, the tat-positive 7TD1 cells sustained the growth of parental 7TD1 cells and showed a dramatic increase in their tumorigenic potency. These results suggest that TAT protein may play a role in the pathogenesis of some HIV1-associated diseases by modulating the expression of host cellular genes.

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          Author and article information

          Journal
          J Exp Med
          The Journal of Experimental Medicine
          The Rockefeller University Press
          0022-1007
          1540-9538
          1 March 1994
          : 179
          : 3
          : 961-971
          Article
          94157417
          10.1084/jem.179.3.961
          2191426
          8113688
          7cb3580a-fde3-48be-a932-5b62b1b3f1c2
          History
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          Medicine
          Medicine

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