THE HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 LONG TERMINAL REPEAT IS ACTIVATED BY MONOFUNCTIONAL AND BIFUNCTIONAL DNA ALKYLATING-AGENTS IN HUMAN-LYMPHOCYTES

The activation of the human immunodeficiency virus, type 1 (HIV-1) by the DNA alkylating agents ethyl methanesulfonate, methyl methanesulfon ate, and mitomycin C was observed in human B lymphocytes transiently t ransfected with plasmids in which the HIV-1 long terminal repeat (LTR) directed the expression of the bacterial chloramphenicol acetyltransf erase gene. Deletion of the two NF-kappaB-binding sites of LTR abolish ed the HIV-1 activation induced by the three mutagens, while deletion of the three Sp1-binding sites slightly reduced it. Electrophoretic mo bility shift assays revealed an increased binding to the kappaB sites of HIV-1 LTR in the nuclear extracts of human B lymphocytes upon mutag en treatment, while binding to Sp1 sites was unaffected. The TAR regio n was also involved in the mutagen- mediated activation of HIV-1 LTR i nasmuch as a small deletion in the TAR sequence (nucleotides +34 to +3 7) greatly decreased the induction of HIV-1 expression. Moreover, an e nhanced binding activity to the TAR DNA sequence (nucleotides +24 to 47) was observed in nuclear extracts of mutagen-treated lymphocytes. T hus, both the enhancer and the 5'-untranslated region of HIV-1 functio nally cooperate in the mutagen-mediated induction of HIV-1 expression.