title: Tumor suppressor SMAR1 mediates cyclin D1 repression by recruitment of the SIN3/histone deacetylase 1 complex.
abstract: Matrix attachment region binding proteins have been shown to play an important role in gene regulation by altering chromatin in a stage- and tissue-specific manner. Our previous studies report that SMAR1, a matrix-associated protein, regresses B16-F1-induced tumors in mice. Here we show SMAR1 targets the cyclin D1 promoter, a gene product whose dysregulation is attributed to breast malignancies. Our studies reveal that SMAR1 represses cyclin D1 gene expression, which can be reversed by small interfering RNA specific to SMAR1. We demonstrate that SMAR1 interacts with histone deacetylation complex 1, SIN3, and pocket retinoblastomas to form a multiprotein repressor complex. This interaction is mediated by the SMAR1(160-350) domain. Our data suggest SMAR1 recruits a repressor complex to the cyclin D1 promoter that results in deacetylation of chromatin at that locus, which spreads to a distance of at least the 5 kb studied upstream of the cyclin D1 promoter. Interestingly, we find that the high induction of cyclin D1 in breast cancer cell lines can be correlated to the decreased levels of SMAR1 in these lines. Our results establish the molecular mechanism exhibited by SMAR1 to regulate cyclin D1 by modification of chromatin.
authors.affiliation: National Center for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India.
authors.forename: Shravanti
authors.initials: S
authors.lastname: Rampalli
authors.forename: L
authors.initials: L
authors.lastname: Pavithra
authors.forename: Altaf
authors.initials: A
authors.lastname: Bhatt
authors.forename: Tapas K
authors.initials: TK
authors.lastname: Kundu
authors.forename: Samit
authors.initials: S
authors.lastname: Chattopadhyay
mesh_terms: D001665:Binding Sites; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D048429:Cell Size; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D019938:Cyclin D1 / Q000737:chemistry* / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism*; D016193:G1 Phase; D015972:Gene Expression Regulation, Neoplastic; D005982:Glutathione Transferase / Q000378:metabolism; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008156:Luciferases / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D012175:Retinoblastoma / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016196:S Phase; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D056264:Sin3 Histone Deacetylase and Corepressor Complex; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C417914:BANP protein, human; D018797:Cell Cycle Proteins; D002843:Chromatin; D017931:DNA Primers; D004268:DNA-Binding Proteins; D006657:Histones; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D016160:Retinoblastoma Protein; C071731:SIN3 protein, S cerevisiae; C099683:SIN3A transcription factor; C492042:SIN3B protein, human; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D019938:Cyclin D1; D008156:Luciferases; D005982:Glutathione Transferase; C110550:HDAC1 protein, human; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases; D056264:Sin3 Histone Deacetylase and Corepressor Complex