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 tar 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.

The expression of the interleukin-6 gene is induced by the Human Immunodeficiency Virus-1 Tat protein / Scala, G.; Ruocco, MARIA ROSARIA; Ambrosino, C.; Mallardo, M.; Giordano, V.; Baldassarre, F.; Dragonetti, E.; Quinto, I.; Venuta, S.. - In: JOURNAL OF EXPERIMENTAL MEDICINE. - ISSN 0022-1007. - STAMPA. - 179:3(1994), pp. 961-971. [10.1084/jem.179.3.961]

The expression of the interleukin-6 gene is induced by the Human Immunodeficiency Virus-1 Tat protein.

RUOCCO, MARIA ROSARIA;M. MALLARDO;
1994

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 tar 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.
1994
The expression of the interleukin-6 gene is induced by the Human Immunodeficiency Virus-1 Tat protein / Scala, G.; Ruocco, MARIA ROSARIA; Ambrosino, C.; Mallardo, M.; Giordano, V.; Baldassarre, F.; Dragonetti, E.; Quinto, I.; Venuta, S.. - In: JOURNAL OF EXPERIMENTAL MEDICINE. - ISSN 0022-1007. - STAMPA. - 179:3(1994), pp. 961-971. [10.1084/jem.179.3.961]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/159494
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