title: BRCA1 regulates GADD45 through its interactions with the OCT-1 and CAAT motifs.
abstract: BRCA1, a breast and ovarian cancer susceptibility gene, has been implicated in gene regulation. Previous studies demonstrate that BRCA1 induces GADD45, a p53-regulated and stress-inducible gene that plays an important role in cellular response to DNA damage. However, the mechanism(s) by which BRCA1 regulates GADD45 remains unclear. In this report, we have shown that BRCA1 activation of the GADD45 promoter is mediated through the OCT-1 and CAAT motifs located at the GADD45 promoter region. Site-directed mutations of both OCT-1 and CAAT motifs abrogate induction of the GADD45 promoter by BRCA1. Both OCT-1 and CAAT motifs are able to confer BRCA1 inducibility in a non-related minimal promoter. Physical associations of BRCA1 protein with transcription factors Oct-1 and NF-YA, which directly bind to the OCT-1 and CAAT motifs, are established by biotin-streptavidin pull-down and coimmunoprecipitation assays. Such protein interactions are required for interaction of BRCA1 with the GADD45 promoter because either immunodepletion of Oct-1 and NF-YA proteins or mutations in the OCT-1 and CAAT motifs disrupt BRCA1 binding to the GADD45 promoter. These findings indicate that BRCA1 can up-regulate its targeted genes through protein-protein interactions and provide a novel mechanism by which BRCA1 participates in transcriptional regulation.
authors.affiliation: Department of Radiation Oncology, Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Wenhong
authors.initials: W
authors.lastname: Fan
authors.forename: Shunqian
authors.initials: S
authors.lastname: Jin
authors.forename: Tong
authors.initials: T
authors.lastname: Tong
authors.forename: Hongcheng
authors.initials: H
authors.lastname: Zhao
authors.forename: Feiyue
authors.initials: F
authors.lastname: Fan
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Antinore
authors.forename: Baskaran
authors.initials: B
authors.lastname: Rajasekaran
authors.forename: Min
authors.initials: M
authors.lastname: Wu
authors.forename: Qimin
authors.initials: Q
authors.lastname: Zhan
mesh_terms: D020816:Amino Acid Motifs; D019313:BRCA1 Protein / Q000378:metabolism*; D001483:Base Sequence; D001710:Biotin / Q000378:metabolism; D023081:CCAAT-Binding Factor / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D019398:Genes, BRCA1; D051863:Host Cell Factor C1; D006801:Humans; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D050811:Octamer Transcription Factor-1; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D000097642:GADD45 Proteins
chemical_list: D019313:BRCA1 Protein; D001710:Biotin; D023081:CCAAT-Binding Factor; D022762:CCAAT-Enhancer-Binding Proteins; D015500:Chloramphenicol O-Acetyltransferase; D004268:DNA-Binding Proteins; D051863:Host Cell Factor C1; D047908:Intracellular Signaling Peptides and Proteins; D050811:Octamer Transcription Factor-1; D011506:Proteins; D014157:Transcription Factors; D000097642:GADD45 Proteins; C497692:HCFC1 protein, human; C492061:NFYA protein, human; C494165:POU2F1 protein, human