HIV GENOME TRANSCRIPTION INDUCED BY POLYO MA-VIRUS MIDDLE T-ANTIGEN THROUGH BOTH ENHANCER-DEPENDENT AND PROMOTER-DEPENDENT LTR ACTIVATION

In order to understand the regulation of HIV genome transcription indu ced by cell stimulation through transmembrane receptors, we have trans fected cells with polyoma middle T antigen (PyMT) expression vectors, thus mimicking activated receptor-dependent cell stimulation. PyMT-exp ressing Cos7 cells provided an environment where transcription of an H IV provirus was activated. PyMT expression induced the activity of bot h enhancer- and piomoter-dependent HIV-LTR luciferase vectors. Inducti on of the HIV promoter domain depended on Sp1-binding sites and could be blocked by Wortmannin, an inhibitor of phosphatidylinositol 3-kinas e (PI3K). This indicates that PyMT-induced HIV transcription and repli cation are controlled by bath the enhancer and promoter domains of the HIV-LTR. The latter, but not the former, was induced in a PI3K-depend ent way. Thus at least 2 different transduction pathways appear to col laborate for induction of full HIV genome transcription in activated c ells.