title: Regulation of serum response factor activity and smooth muscle cell apoptosis by chromodomain helicase DNA-binding protein 8.
abstract: Serum response factor (SRF) is a widely expressed protein that plays a key role in the regulation of smooth muscle differentiation, proliferation, migration, and apoptosis. It is generally accepted that one mechanism by which SRF regulates these diverse functions is through pathway-specific cofactor interactions. A novel SRF cofactor, chromodomain helicase DNA binding protein 8 (CHD8), was isolated from a yeast two-hybrid screen using SRF as bait. CHD8 is highly expressed in adult smooth muscle tissues. Coimmunoprecipitation assays from A10 smooth muscle cells demonstrated binding of endogenous SRF and CHD8. Data from GST-pulldown assays indicate that the NH(2)-terminus of CHD8 can interact directly with the MADS domain of SRF. Adenoviral-mediated knockdown of CHD8 in smooth muscle cells resulted in attenuated expression of SRF-dependent, smooth muscle-specific genes. Knockdown of CHD8, SRF, or CTCF, a previously described binding partner of CHD8, in A10 VSMCs also resulted in a marked induction of apoptosis. Mechanistically, apoptosis induced by CHD8 knockdown was accompanied by attenuated expression of the anti-apoptotic proteins, Birc5, and CARD10, whereas SRF knockdown attenuated expression of CARD10 and Mcl-1, but not Birc5, and CTCF knockdown attenuated expression of Birc5. These data suggest that CHD8 plays a dual role in smooth muscle cells modulating SRF activity toward differentiation genes and promoting cell survival through interactions with both SRF and CTCF to regulate expression of Birc5 and CARD10.
authors.affiliation: Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5120, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Rodenberg
authors.forename: April M
authors.initials: AM
authors.lastname: Hoggatt
authors.forename: Meng
authors.initials: M
authors.lastname: Chen
authors.forename: Ketrija
authors.initials: K
authors.lastname: Touw
authors.forename: Rebekah
authors.initials: R
authors.lastname: Jones
authors.forename: B Paul
authors.initials: BP
authors.lastname: Herring
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001483:Base Sequence; D053468:CARD Signaling Adaptor Proteins / Q000235:genetics / Q000378:metabolism; D000076246:CCCTC-Binding Factor; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D026362:Serum Response Factor / Q000235:genetics / Q000378:metabolism*; D000077022:Survivin; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: C117749:Birc5 protein, mouse; D053468:CARD Signaling Adaptor Proteins; D000076246:CCCTC-Binding Factor; C523331:CHD8 protein, human; C000619697:CTCF protein, human; C498975:Card10 protein, mouse; C000619698:Ctcf protein, mouse; D004268:DNA-Binding Proteins; D051034:Inhibitor of Apoptosis Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D026362:Serum Response Factor; D000077022:Survivin; D014157:Transcription Factors; C515814:duplin protein, mouse