title: The histone demethylase, Jmjd1a, interacts with the myocardin factors to regulate SMC differentiation marker gene expression.
abstract: We and others have previously shown that the myocardin transcription factors play critical roles in the regulation of smooth muscle cell (SMC) differentiation marker gene expression. In a yeast 2-hybrid screen for proteins that interact with myocardin-related transcription factor-A (MRTF-A), we identified the histone 3 lysine 9 (H3K9)-specific demethylase, Jmjd1a. GST pull-down assays demonstrated that Jmjd1a bound all 3 myocardin family members, and further mapping studies showed that the jumonjiC domain of Jmjd1a was sufficient to mediate this interaction. Overexpression of Jmjd1a in multipotential 10T1/2 cells decreased global levels of di-methyl H3K9, stimulated the SM alpha-actin and SM22 promoters, and synergistically enhanced MRTF-A- and myocardin-dependent transactivation. Using chromatin immunoprecipitation assays, we also demonstrated that TGF-beta-mediated upregulation of SMC differentiation marker gene expression in 10T1/2 cells was associated with decreased H3K9 dimethylation at the CArG-containing regions of the SMC differentiation marker gene promoters. Importantly, knockdown of Jmjd1a in 10T1/2 cells and primary rat aortic SMCs by retroviral delivery of siRNA attenuated TGF-beta-induced upregulation of endogenous SM myosin heavy chain expression. These effects were concomitant with increased H3K9 dimethylation at the SMC differentiation marker gene promoters and with inhibition of MRTF-A-dependent transactivation of the SMC-specific transcription. These results suggest, for the first time, that SMC differentiation marker gene expression is regulated by H3K9 methylation and that the effects of the myocardin factors on SMC-specific transcription may involve the recruitment of Jmjd1a to the SMC-specific promoters.
authors.affiliation: Department of Pathology, University of North Carolina, Chapel Hill, NC 27599-7525, USA.
authors.forename: Kashelle
authors.initials: K
authors.lastname: Lockman
authors.forename: Joan M
authors.initials: JM
authors.lastname: Taylor
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Mack
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000502:physiology*; D006657:Histones / Q000378:metabolism; D056484:Jumonji Domain-Containing Histone Demethylases; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000201:enzymology*; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D010089:Oxidoreductases, N-Demethylating / Q000378:metabolism*; D051381:Rats; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D000099251:Myocardin
chemical_list: D015415:Biomarkers; D006657:Histones; D056484:Jumonji Domain-Containing Histone Demethylases; D009687:Nuclear Proteins; D010089:Oxidoreductases, N-Demethylating; D015534:Trans-Activators; D000099251:Myocardin; C511173:Mrtfa protein, mouse; C511045:Kdm3a protein, mouse