title: Regulation of connexin43 expression by c-fos and c-jun in myometrial cells.
abstract: Labor is associated with a dramatic increase in the myometrial expression of connexin43 (Cx43) which is thought to mediate myocyte contractile coupling. The transcription factor c-fos is also dramatically increased prior to the onset of labor and is therefore a potential regulator of Cx43. The promoter region of Cx43 contains a conserved activator protein-1 (AP-1) site, which binds dimers of Fos and Jun proteins. We constructed expression vectors for c-Fos and c-Jun to investigate the role of these transcription factors in the regulation of Cx43 expression. These expression vectors were then co-transfected into SHM (syrian hamster myocyte) cells with a Cx43 promoter-Luciferase vector. The combinations of c-Fos and c-Jun proteins activated the Cx43 promoter while c-Jun alone had no effect on Cx43 promoter activity. Mutation of the AP-1 site was found to reduce this responsiveness. These data indicate that the transcription factors c-Fos and c-Jun are important in the regulation of Cx43 expression.
authors.affiliation: Program in Development and Fetal Health, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada.
authors.forename: J A
authors.initials: JA
authors.lastname: Mitchell
authors.forename: S J
authors.initials: SJ
authors.lastname: Lye
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D018031:Connexin 43 / Q000235:genetics* / Q000378:metabolism; D006224:Cricetinae; D005260:Female; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005822:Genetic Vectors; D007743:Labor, Obstetric / Q000378:metabolism; D032342:Muscle Cells / Q000166:cytology / Q000502:physiology; D009215:Myometrium / Q000166:cytology / Q000378:metabolism*; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D018808:Transcription Factor AP-1 / Q000378:metabolism
chemical_list: D018031:Connexin 43; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1