Activation of the human immunodeficiency virus type 1 long terminal repeat by transforming mutants of human p53.
We have studied the effects of human wild-type and mutant p53s on the long terminal repeat (LTR) promoter of human immunodeficiency virus type 1 (HIV). HeLa cells were cotransfected with a wild-type or mutant p53 expression plasmid and a plasmid containing a chloramphenicol acetyltransferase reporter gene under HIV LTR promoter control. As expected, expression of wild-type p53 inhibited promoter function. Expression of a p53 mutated at any one of the four amino acid positions 175, 248, 273, and 281 correlated with a significant increase of the HIV promoter activity. The HIV LTR was also significantly activated in Saos-2 cells that do not express endogenous p53. This finding suggests a gain-of-transactivation function by mutation of the p53 gene. Cotransfection of wild-type and mutant p53-281G expression plasmids indicated that either the wild type or the mutant was dominant in inhibiting or enhancing promoter activity, respectively, when transfected in excess of the other. Transfection experiments showed transactivation even when the Sp1, NF-kappa B, and TATA sites in the LTR were individually mutated. Synthetic minimal promoter constructs containing two Sp1 sites or two NF-kappa B sites or an ATF site are also significantly activated by the mutant p53-281G. Thus, the mutant protein may activate transcription through interaction with either a general transcription factor or a common factor that bridges the basal transcription machinery and the transcription factors Sp1, NF-kappa B, and ATF.
Subler
M A
MA
Department of Microbiology, University of Texas Health Science Center, San Antonio 78284.
Martin
D W
DW
Deb
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D051696:Activating Transcription Factors; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001798:Blood Proteins / Q000378:metabolism; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000378:metabolism; D017930:Genes, Reporter; D016158:Genes, p53; D016325:HIV Long Terminal Repeat / Q000235:genetics*; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000378:metabolism; D035181:TATA-Box Binding Protein; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection; D014170:Transformation, Genetic; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000494:pharmacology
D051696:Activating Transcription Factors; D001798:Blood Proteins; D004268:DNA-Binding Proteins; D016328:NF-kappa B; D016329:Sp1 Transcription Factor; D035181:TATA-Box Binding Protein; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53