title: Regulatory factor for X-box family proteins differentially interact with histone deacetylases to repress collagen alpha2(I) gene (COL1A2) expression.
abstract: Our studies indicate that the regulatory factor for X-box (RFX) family proteins repress collagen alpha2(I) gene (COL1A2) expression (Xu, Y., Wang, L., Buttice, G., Sengupta, P. K., and Smith, B. D. (2003) J. Biol. Chem. 278, 49134-49144; Xu, Y., Wang, L., Buttice, G., Sengupta, P. K., and Smith, B. D. (2004) J. Biol. Chem. 279, 41319-41332). In this study, we examined the mechanism(s) underlying the repression of collagen gene by RFX proteins. Two members of the RFX family, RFX1 and RFX5, associate with distinct sets of co-repressors on the collagen transcription start site in vitro. RFX5 specifically interacts with histone deacetylase 2 (HDAC2) and the mammalian transcriptional repressor (mSin3B), whereas RFX1 preferably interacts with HDAC1 and mSin3A. HDAC2 cooperates with RFX5 to down-regulate collagen promoter activity, whereas HDAC1 enhances inhibition of collagen promoter activity by RFX1. Interferon-gamma promotes the recruitment of RFX5/HDAC2/mSin3B to the collagen transcription start site but decreases the occupancy by RFX1/mSin3A as manifested by chromatin immunoprecipitation assay. RFX1 binds to the methylated collagen sequence with much higher affinity than unmethylated sequence, recruiting more HDAC1 and mSin3A. The DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine, which inhibits DNA methylation, reduces RFX1/HDAC1 binding to the collagen transcription start site in chromatin immunoprecipitation assays. Finally, both RFX1 and RFX5 are acetylated in vivo. Trichostatin A stimulates the acetylation of RFX proteins and activates the collagen promoter activity. Collectively, our data strongly indicate two separate pathways for RFX proteins to repress collagen gene expression as follows: one for RFX5/HDAC2 in interferon-gamma-mediated repression, and the other for RFX1/HDAC1 in methylation-mediated collagen silencing.
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Xu
authors.forename: Pritam K
authors.initials: PK
authors.lastname: Sengupta
authors.forename: Edward
authors.initials: E
authors.lastname: Seto
authors.forename: Barbara D
authors.initials: BD
authors.lastname: Smith
mesh_terms: D024042:Collagen Type I / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005347:Fibroblasts; D005354:Fibrosarcoma / Q000473:pathology; D005786:Gene Expression Regulation; D056284:Histone Deacetylase 1; D056464:Histone Deacetylase 2; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000502:physiology; D008168:Lung / Q000166:cytology; D000071701:Regulatory Factor X Transcription Factors; D000071716:Regulatory Factor X1; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D024042:Collagen Type I; D004268:DNA-Binding Proteins; C000605537:RFX1 protein, human; C093524:RFX5 protein, human; D000071701:Regulatory Factor X Transcription Factors; D000071716:Regulatory Factor X1; D012097:Repressor Proteins; D014157:Transcription Factors; D007371:Interferon-gamma; C110550:HDAC1 protein, human; D056284:Histone Deacetylase 1; D056464:Histone Deacetylase 2; D006655:Histone Deacetylases