title: Atrial natriuretic peptide suppresses endothelin gene expression and proliferation in cardiac fibroblasts through a GATA4-dependent mechanism.
abstract: OBJECTIVE
  Atrial natriuretic peptide (ANP) is a hormone that has both antihypertrophic and antifibrotic properties in the heart. We hypothesized that myocyte-derived ANP inhibits endothelin (ET) gene expression in fibroblasts.
  
  
  RESULTS
  We have investigated the mechanism(s) involved in the antiproliferative effect of ANP on cardiac fibroblasts in a cell culture model. We found that cardiac myocytes inhibited DNA synthesis in co-cultured cardiac fibroblasts as did treatment with the ET-1 antagonist BQ610. The effect of co-culture was reversed by antibody directed against ANP or the ANP receptor antagonist HS-142-1. ANP inhibited the expression of the ET-1 gene and ET-1 gene promoter activity in cultured fibroblasts. The site of the inhibition was localized to a GATA-binding site positioned between -132 and -135 upstream from the transcription start site. GATA4 expression was demonstrated in cardiac fibroblasts, GATA4 bound the ET-1 promoter both in vitro and in vivo, and siRNA-mediated knockdown of GATA4 inhibited ET-1 expression. ET-1 treatment resulted in increased levels of phospho-serine(105) GATA4 in cardiac fibroblasts and this induction was partially suppressed by co-treatment with ANP.
  
  
  CONCLUSIONS
  Collectively, these findings suggest that locally produced ET-1 serves as an autocrine stimulator of fibroblast proliferation, that ANP produced in neighbouring myocytes serves as a paracrine inhibitor of this proliferation, and that the latter effect operates through a reduction in GATA4 phosphorylation and coincident reduction in GATA4-dependent transcriptional activity.
authors: Department of Medicine, University of California at San Francisco, San Francisco, CA, USA.
authors: Denis J
authors: DJ
authors: Glenn
authors: Dolkun
authors: D
authors: Rahmutula
authors: Minobu
authors: M
authors: Nishimoto
authors: Faquan
authors: F
authors: Liang
authors: David G
authors: DG
authors: Gardner
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D019898:Autocrine Communication; D001665:Binding Sites; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D004261:DNA Replication; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D019332:Endothelin-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D050991:GATA4 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D006352:Heart Ventricles / Q000166:cytology / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology; D019899:Paracrine Communication; D010766:Phosphorylation; D011134:Polysaccharides / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D017461:Receptors, Atrial Natriuretic Factor / Q000037:antagonists & inhibitors / Q000378:metabolism; D012694:Serine; D015398:Signal Transduction; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D019332:Endothelin-1; D050991:GATA4 Transcription Factor; C084365:Gata4 protein, rat; C072551:HS 142-1; D009842:Oligopeptides; D011134:Polysaccharides; C087220:BQ 610; D012694:Serine; D009320:Atrial Natriuretic Factor; D048049:Extracellular Signal-Regulated MAP Kinases; D017461:Receptors, Atrial Natriuretic Factor