title: Sp1-mediated transcriptional regulation of NFBD1/MDC1 plays a critical role in DNA damage response pathway.
abstract: NFBD1/MDC1 is a large nuclear protein with an anti-apoptotic potential which participates in DNA damage response. Recently, we have demonstrated that NFBD1 has an inhibitory effect on pro-apoptotic p53 and DNA damage-induced transcriptional repression of NFBD1 plays an important role in p53-dependent apoptotic response. In this study, we have found that NFBD1 promoter region contains canonical Sp1-, STAT-1- and NF-Y-binding sites and finally we have identified Sp1 as a transcriptional activator for NFBD1. The 5'-RACE and bioinformatic analyses revealed that NFBD1 encodes at least four transcriptional variants arising from distinct transcriptional start sites. Luciferase reporter assays using a series of NFBD1 promoter deletion mutants demonstrated that the proximal Sp1-binding site is required for the transcriptional activation of NFBD1. Indeed, the endogenous Sp1 was recruited onto the proximal Sp1-binding site as examined by chromatin immunoprecipitation (ChIP) assay and siRNA-mediated knockdown of the endogenous Sp1 in HeLa cells reduced the expression levels of NFBD1, which renders cells sensitive to adriamycin (ADR). In support of this notion, mithramycin A (MA, Sp1 inhibitor) treatment resulted in a significant down-regulation of NFBD1. Taken together, our present findings suggest that Sp1-mediated transcriptional regulation of NFBD1 plays an important role in the regulation of DNA damage response.
authors.affiliation: Division of Biochemistry, Chiba Cancer Center Research Institute, Chiba 260-8717, Japan.
authors.forename: Youquan
authors.initials: Y
authors.lastname: Bu
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Suenaga
authors.forename: Sayaka
authors.initials: S
authors.lastname: Ono
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Koda
authors.forename: Fangzhou
authors.initials: F
authors.lastname: Song
authors.forename: Akira
authors.initials: A
authors.lastname: Nakagawara
authors.forename: Toshinori
authors.initials: T
authors.lastname: Ozaki
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D001483:Base Sequence; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000502:physiology; D008926:Plicamycin / Q000031:analogs & derivatives / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics* / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C413163:MDC1 protein, human; D009687:Nuclear Proteins; D016329:Sp1 Transcription Factor; D015534:Trans-Activators; C066851:mithramycin A; D008926:Plicamycin