title: Downregulation of bone morphogenetic protein 4 expression in coronary arterial endothelial cells: role of shear stress and the cAMP/protein kinase A pathway.
abstract: OBJECTIVE
  Bone morphogenetic protein 4 (BMP-4) is a transforming growth factor beta family member cytokine that exerts proinflammatory effects on the endothelium and is likely to play a role in atherogenesis. Recent studies suggested that atheroprotective levels of shear stress control endothelial BMP-4 expression; however, the underlying mechanisms remained unknown.
  
  
  RESULTS
  We found that shear stress downregulated BMP-4 expression in human and rat coronary arterial endothelial cells (CAECs) as well as in cultured mesenteric arterioles, although it had no effect on the expression of BMP-2, a related cytokine. In human coronary arterial endothelial cells, 8-bromo-cAMP, the adenylate cyclase activator forskolin, or a cAMP-dependent protein kinase (PKA) activator effectively decreased BMP-4 expression, mimicking the effects of shear stress. Indeed, shear stress induced the nuclear translocation of PKA-c, and inhibition of PKA attenuated the effects of shear stress and forskolin on BMP-4 expression. RNA decay assay and BMP-4 promoter-driven luciferase reporter gene assay showed that cAMP regulates BMP-4 expression at the transcriptional level.
  
  
  CONCLUSIONS
  Laminar shear stress and the cAMP/PKA pathway are important negative regulators of BMP-4 expression in the vascular endothelium. Because BMP-4 elicits endothelial activation and dysfunction, hypertension, and vascular calcification, inhibition of BMP-4 expression by shear stress and the cAMP/PKA pathway is likely to exert antiatherogenic and vasculoprotective effects.
authors.affiliation: Department of Physiology, New York Medical College, Valhalla, New York 10595, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Csiszar
authors.forename: Nazar
authors.initials: N
authors.lastname: Labinskyy
authors.forename: Kira E
authors.initials: KE
authors.lastname: Smith
authors.forename: Aracelie
authors.initials: A
authors.lastname: Rivera
authors.forename: Erik N T P
authors.initials: EN
authors.lastname: Bakker
authors.forename: Hanjoong
authors.initials: H
authors.lastname: Jo
authors.forename: Jason
authors.initials: J
authors.lastname: Gardner
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Orosz
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Ungvari
mesh_terms: D000818:Animals; D001160:Arterioles / Q000378:metabolism; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D015536:Down-Regulation; D042783:Endothelial Cells / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013152:Splanchnic Circulation; D013314:Stress, Mechanical; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: C525809:BMP4 protein, human; C525811:Bmp4 protein, rat; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D012333:RNA, Messenger; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases