The Human Immunodeficiency Virus Type-l Tat Protein Upregulates Bcl-2 Gene Expression in Jurkat T-cell Lines and Primary Peripheral Blood Mononuclear Cells

The regulatory Tat protein of human immunodeficiency virus type-l (HIV-1) exerts a pleyotropic activity on the survival and proliferation of different cell types in culture. In this report, we investigated the effect of either endogenous or exogenous Tat on Bcl-2 proto-oncogene expression and cell survival in Jurkat T-cell lines and primary peripheral blood mononuclear cells. Stable and transient transfections of Jurkat cells with the cDNA of tat and a plasmid containing Bcl2 promoter in front of CAT (Bcl-2 PrlCAT) stimulated CAT activity and showed an increase of Bcl-2 mRNA and protein expression. This effect was specifically related to tat, because Jurkat cells transfected with the cDNA of tat in antisense orientation, tat carrying a mutation in the amino acid cysp-glp, or the control vector alone (pRPneo-SW) did not show any significant difference in Bcl-2 promoter activity with respect to parental Jurkat cells. We also observed a specific correlation between tat-induced Bcl-2 gene expression and inhibition of apoptosis induced by serum with-