Cloning and characterization of the human BAG-1 gene promoter: upregulation by tumor-derived p53 mutants

Oncogene. 1999 Aug 12;18(32):4546-53. doi: 10.1038/sj.onc.1202843.

Abstract

BAG-1 is an anti-apoptotic protein that interacts with Bcl-2, Bcl-XL, Hsp70/Hsc70, Raf-1 and numerous hormone or growth factor receptors. Recently, BAG-1 has been found to be overexpressed in a variety of human cancer cell lines and some tumors. However, the molecular mechanism of BAG-1 upregulation is still unclear. In this study, we cloned 0.9 kb of human genomic DNA, BGEV, 5' flanking the BAG-1 open reading frame. BGEV subcloned into a promoterless luciferase reporter vector conferred high promoter activity in various human cancer cell lines. Deletion analysis of this sequence localized the region of maximal BAG-1 promoter activity from nucleotide positions -353 to -54, upstream of the first start codon CTG. Sequence analysis of the BAG-1 promoter region showed the absence of a TATA box but identified a CCAAT box, several GC boxes, a CpG island and several transcriptional factor binding sites, which may be important in the regulation of BAG-1 transcription. Most importantly, functional characterization of the BAG-1 promoter in vivo demonstrated that gain-of-function p53 mutants derived from human tumors upregulated the transcription of BAG-1 RNA and the expression of a reporter gene from the BAG-1 promoter. These results indicated that we have isolated the functional constitutive BAG-1 promoter. Furthermore, the data suggested that overexpression of BAG-1 in some tumors may be due to upregulation of the human BAG-1 promoter by mutant p53.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Carrier Proteins / genetics*
  • Chromosome Mapping
  • Cloning, Molecular
  • DNA-Binding Proteins
  • HeLa Cells
  • Humans
  • Molecular Sequence Data
  • Mutation
  • Promoter Regions, Genetic*
  • Sequence Analysis, DNA
  • Transcription Factors
  • Transcriptional Activation
  • Tumor Cells, Cultured
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • Tumor Suppressor Protein p53 / pharmacology
  • Up-Regulation*

Substances

  • BCL2-associated athanogene 1 protein
  • Carrier Proteins
  • DNA-Binding Proteins
  • Transcription Factors
  • Tumor Suppressor Protein p53