title: A cis-acting element in Rous sarcoma virus long terminal repeat required for promoter repression by HeLa nuclear protein p21.
abstract: HeLa cell basic nuclear protein (p21), which represses Rous sarcoma virus long terminal repeat (RSV LTR) promoter activity, diminished v-src expression and the appearance at permissive temperature of the transformed phenotype in tsRSVLA23 Rat-1, a cell line transformed with a temperature-sensitive mutant of RSV. Nuclear run-on analyses using COS-1 cells cotransfected with p21 cDNA and chloramphenicol acetyltransferase reporter indicated that p21 inhibits transcription initiation by targeting a region in the RSV LTR promoter between positions -108 and -85 upstream of the cap site. Insertion of this 24-base pair sequence in place of one of the 72-base pair enhancers in the SV40 early promoter rendered it sensitive to p21 repression. Electrophoretic mobility shift assays using a synthetic oligomer corresponding to the 24-base pair LTR promoter element revealed that p21 altered the pattern of protein.DNA complex formation apparently without binding DNA directly. Complex formation assayed by UV cross-linking and DNA affinity chromatography indicated further that a cellular factor which can interact with this element was decreased in cells transfected with p21 expression plasmid. The results indicate that p21 repression of RSV LTR is mediated by a cis-acting element and may occur by alteration of protein complexes formed on this promoter element.
authors.affiliation: Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey 08854, USA.
authors.forename: C H
authors.initials: CH
authors.lastname: Yeh
authors.forename: A J
authors.initials: AJ
authors.lastname: Shatkin
mesh_terms: D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics*; D001483:Base Sequence; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D051381:Rats; D012091:Repetitive Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D012097:Repressor Proteins; C087628:TCEAL1 protein, human; D014157:Transcription Factors; D004247:DNA