title: The Transcription Factor MEF2 Is a Novel Regulator of Gsta Gene Class in Mouse MA-10 Leydig Cells.
abstract: Testosterone is essential for spermatogenesis and the development of male sexual characteristics. However, steroidogenesis produces a significant amount of reactive oxygen species (ROS), which can disrupt testosterone production. The myocyte enhancer factor 2 (MEF2) is an important regulator of organogenesis and cell differentiation in various tissues. In the testis, MEF2 is present in Sertoli and Leydig cells throughout fetal and adult life. MEF2-deficient MA-10 Leydig cells exhibit a significant decrease in steroidogenesis concomitant with a reduction in glutathione S-transferase (GST) activity and in the expression of the 4 Gsta members (GST) that encode ROS inactivating enzymes. Here, we report a novel role for MEF2 in ROS detoxification by directly regulating Gsta expression in Leydig cells. Endogenous Gsta1-4 mRNA levels were decreased in MEF2-deficient MA-10 Leydig cells. Conversely, overexpression of MEF2 increased endogenous Gsta1 levels. MEF2 recruitment to the proximal Gsta1 promoter and direct binding on the -506-bp MEF2 element were confirmed by chromatin immunoprecipitation and DNA precipitation assays. In MA-10 Leydig cells, MEF2 activates the Gsta1 promoter and cooperates with Ca(2+)/calmodulin-dependent kinases I to further enhance Gsta1 promoter activity. These effects were lost when the -506-bp MEF2 element was mutated or when a MEF2-Engrailed dominant negative protein was used. Similar results were obtained on the Gsta2, Gsta3, and Gsta4 promoters, suggesting a global role for MEF2 factors in the regulation of all 4 Gsta genes. Altogether, our results identify a novel role for MEF2 in the expression of genes involved in ROS detoxification, a process essential for adequate testosterone production in Leydig cells.
authors.affiliation: Reproduction, Mother and Child Health (M.D.-L., C.B., F.B., J.J.T.), 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.forename: Mickaël
authors.initials: M
authors.lastname: Di-Luoffo
authors.affiliation: Reproduction, Mother and Child Health (M.D.-L., C.B., F.B., J.J.T.), 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.forename: Catherine
authors.initials: C
authors.lastname: Brousseau
authors.affiliation: Reproduction, Mother and Child Health (M.D.-L., C.B., F.B., J.J.T.), 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.forename: Francis
authors.initials: F
authors.lastname: Bergeron
authors.affiliation: Reproduction, Mother and Child Health (M.D.-L., C.B., F.B., J.J.T.), 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.forename: Jacques J
authors.initials: JJ
authors.lastname: Tremblay
mesh_terms: D000818:Animals; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1 / Q000378:metabolism; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D018507:Gene Expression Regulation, Developmental; D055786:Gene Knockout Techniques; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007985:Leydig Cells; D064326:MEF2 Transcription Factors / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013739:Testosterone / Q000096:biosynthesis*
chemical_list: D007527:Isoenzymes; D064326:MEF2 Transcription Factors; C578036:Mef2a protein, mouse; C578039:Mef2b protein, mouse; C578041:Mef2c protein, mouse; C578044:Mef2d protein, mouse; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013739:Testosterone; C000605561:GSTA2 protein, mouse; C000594000:GSTA3 protein, mouse; C529117:GSTA4-4 protein, mouse; D005982:Glutathione Transferase; C119995:glutathione S-transferase alpha; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; C517598:Camk1 protein, mouse