title: Phorbol ester enhances human immunodeficiency virus-promoted gene expression and acts on a repeated 10-base-pair functional enhancer element.
abstract: T-cell activation pathways are involved in the regulation of human immunodeficiency virus (HIV) expression. Phorbol 12-myristate 13-acetate (PMA) is a potent inducer of T-cell immune functions and has recently been demonstrated to increase viral replication in cell lines infected with HIV. To define sequences required for viral induction by PMA. T-cell lines were transiently transfected with viral long terminal repeat (LTR) sequences directing chloramphenicol acetyltransferase (CAT) gene expression. PMA added to transfected cell cultures 24 h before harvest reproducibly increased both CAT mRNA and enzyme expression 2- to 2-fold. Sequences necessary for basal and PMA-induced levels of CAT expression were determined by deletion and enhancer reconstitution constructs with fragments and oligonucleotides from the original LTR-CAT expression plasmid. PMA-inducible and basal activity required tandem repeats of a core enhancer element (GGGACTTTCC) located in the LTR between -105 and -82 relative to the RNA start site. The enhancerlike sequence could be inserted at a site distant to the CAT gene open reading frame and functioned in a position- and orientation-independent manner. The data thus define a transcriptionally active regulatory-enhancer element critical to the control of HIV gene expression.
mesh_terms: D002874:Chromosome Mapping; D004252:DNA Mutational Analysis; D004279:DNA, Viral / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation / Q000187:drug effects*; D006678:HIV / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D013601:T-Lymphocytes / Q000382:microbiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D004279:DNA, Viral; D013755:Tetradecanoylphorbol Acetate