title: MEF2 Cooperates With Forskolin/cAMP and GATA4 to Regulate Star Gene Expression in Mouse MA-10 Leydig Cells.
abstract: In Leydig cells, steroidogenic acute regulatory protein (STAR) participates in cholesterol shuttling from the outer to the inner mitochondrial membrane, the rate-limiting step in steroidogenesis. Steroid hormone biosynthesis and steroidogenic gene expression are regulated by LH, which activates various signaling pathways and transcription factors, including cAMP/Ca(2+)/CAMK (Ca(2+)/calmodulin-dependent kinase)-myocyte enhancer factor 2 (MEF2). The 4 MEF2 transcription factors are essential regulators of cell differentiation and organogenesis in numerous tissues. Recently, MEF2 was identified in Sertoli and Leydig cells of the testis. Here, we report that MEF2 regulates steroidogenesis in mouse MA-10 Leydig cells by acting on the Star gene. In MA-10 cells depleted of MEF2 using siRNAs (small interfering RNAs), STAR protein levels, Star mRNA levels, and promoter activity were significantly decreased. On its own, MEF2 did not activate the mouse Star promoter but was found to cooperate with forskolin/cAMP. By chromatin immunoprecipitation and DNA precipitation assays, we confirmed MEF2 binding to a consensus element located at -232 bp of the Star promoter. Mutation or deletion of the MEF2 element reduced but did not abrogate the MEF2/cAMP cooperation, indicating that MEF2 cooperates with other DNA-bound transcription factor(s). We identified GATA4 (GATA binding protein 4) as a partner for MEF2 in Leydig cells, because mutation of the GATA element abrogated the MEF2/cAMP cooperation on a reporter lacking a MEF2 element. MEF2 and GATA4 interact as revealed by coimmunoprecipitation, and MEF2 and GATA4 transcriptionally cooperate on the Star promoter. Altogether, our results define MEF2 as a novel regulator of steroidogenesis and Star transcription in Leydig cells and identify GATA4 as a key partner for MEF2-mediated action.
authors: Reproduction (C.D., M.D.-L., E.P., J.J.T.), Mother and Child Health, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada G1V 4G2; and Centre de Recherche en Biologie de la Reproduction (J.J.T.), Department of Obstetrics, Gynecology, and Reproduction, Faculty of Medicine, Université Laval, Québec City, Québec, Canada G1V 0A6.
authors: Caroline
authors: C
authors: Daems
authors: Reproduction (C.D., M.D.-L., E.P., J.J.T.), Mother and Child Health, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada G1V 4G2; and Centre de Recherche en Biologie de la Reproduction (J.J.T.), Department of Obstetrics, Gynecology, and Reproduction, Faculty of Medicine, Université Laval, Québec City, Québec, Canada G1V 0A6.
authors: Mickaël
authors: M
authors: Di-Luoffo
authors: Reproduction (C.D., M.D.-L., E.P., J.J.T.), Mother and Child Health, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada G1V 4G2; and Centre de Recherche en Biologie de la Reproduction (J.J.T.), Department of Obstetrics, Gynecology, and Reproduction, Faculty of Medicine, Université Laval, Québec City, Québec, Canada G1V 0A6.
authors: Élise
authors: É
authors: Paradis
authors: Reproduction (C.D., M.D.-L., E.P., J.J.T.), Mother and Child Health, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada G1V 4G2; and Centre de Recherche en Biologie de la Reproduction (J.J.T.), Department of Obstetrics, Gynecology, and Reproduction, Faculty of Medicine, Université Laval, Québec City, Québec, Canada G1V 0A6.
authors: Jacques J
authors: JJ
authors: Tremblay
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D050991:GATA4 Transcription Factor / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics*; D055785:Gene Knockdown Techniques; D012739:Gonadal Steroid Hormones / Q000096:biosynthesis; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D064326:MEF2 Transcription Factors / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D010750:Phosphoproteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D050991:GATA4 Transcription Factor; C484171:Gata4 protein, mouse; D012739:Gonadal Steroid Hormones; D064326:MEF2 Transcription Factors; D010750:Phosphoproteins; D012333:RNA, Messenger; D000098682:Steroidogenic Acute Regulatory Protein; D005576:Colforsin; D007986:Luteinizing Hormone; D000242:Cyclic AMP