title: Identification of a p53-dependent negative response element in the bcl-2 gene.
abstract: Recently, we have shown that the p53 tumor suppressor gene product can inhibit expression of the bcl-2 gene. In this report, we explored the molecular basis for p53-mediated down-regulation of bcl-2 gene expression using a cotransfection approach involving p53 expression plasmids and chloramphenicol acetyltransferase (CAT) reporter gene constructs containing regions from the bcl-2 gene. When transfected into a p53-deficient human lung cancer cell line H358, reporter gene constructs containing only the promoter region of bcl-2 and upstream sequences were not suppressed by p53. Inclusion of bcl-2 gene sequences corresponding to the 5' untranslated region in bcl-2/CAT constructs, however, resulted in p53-dependent down-regulation. A 195-base pair segment from the bcl-2 gene 5' untranslated region was found to be capable of conferring p53-dependent repression on a heterologous expression plasmid containing CAT under the control of an SV40 immediate early-region promoter. This p53-negative response element functioned in an orientation-independent manner when placed either upstream or downstream of the SV40-CAT transcription unit. The results demonstrate the existence of a negative response element in the bcl-2 gene through which p53 may either directly or indirectly transcriptionally down-regulate expression of this gene involved in the regulation of programmed cell death.
authors.affiliation: La Jolla Cancer Research Foundation, Cancer Research Center, California 92037.
authors.forename: T
authors.initials: T
authors.lastname: Miyashita
authors.forename: M
authors.initials: M
authors.lastname: Harigai
authors.forename: M
authors.initials: M
authors.lastname: Hanada
authors.forename: J C
authors.initials: JC
authors.lastname: Reed
mesh_terms: D001483:Base Sequence; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D015536:Down-Regulation; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D005809:Genes, Regulator; D017930:Genes, Reporter; D016158:Genes, p53; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2; D013539:Simian virus 40 / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*
chemical_list: D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D015500:Chloramphenicol O-Acetyltransferase