title: Nitric oxide regulates shear stress-induced early growth response-1. Expression via the extracellular signal-regulated kinase pathway in endothelial cells.
abstract: Endothelial cells (ECs) subjected to shear stress constantly release nitric oxide (NO). The effect of NO on shear stress-induced endothelial responses was examined. ECs subjected to shear stress induced a transient and shear force-dependent increase in early growth response-1 (Egr-1) mRNA levels. Treatment of ECs with an NO donor, S-nitroso-N-acetylpenicillamine (SNAP) or 3-morpholinosydnonimine (SIN-1), inhibited this shear stress-induced Egr-1 expression. Conversely, an NO synthase inhibitor to ECs, N(G)-monomethyl-L-arginine, augmented this Egr-1 expression. NO modulation of Egr-1 expression was demonstrated by functional analysis of Egr-1 promoter activity using a chimera containing the Egr-1 promoter region (-698 bp) and reporter gene luciferase. In contrast to the enhanced promoter activity after N(G)-monomethyl-L-arginine treatment, shear stress-induced Egr-1 promoter activity was attenuated after ECs were treated with an NO donor. ECs cotransfected with a dominant negative mutant of Ras (RasN17), Raf-1 (Raf301), or a catalytically inactive mutant of extracellular signal-regulated kinase (ERK)-2 (mERK) inhibited shear stress-induced Egr-1 promoter activity. NO modulation of the signaling pathway was shown by its inhibitory effect on shear stress-induced ERK1/ERK2 phosphorylation and activity. This inhibitory effect was further substantiated by the inhibition of NO on both the shear stress-induced transcriptional activity of Elk-1 (an ERK substrate) and the promoter activity of a reporter construct containing serum response element. NO-treated ECs resulted in a reduction of binding of nuclear proteins to the Egr-1 binding sequences in the platelet-derived growth factor-A promoter region. These results indicate that shear stress-induced Egr-1 expression is modulated by NO via the ERK signaling pathway in ECs. Our findings support the importance of NO as a negative regulator in endothelial responses to hemodynamic forces.
authors.affiliation: Cardiovascular Division, Institute of Biomedical Sciences, Academia Sinica, Taiwan University, Taipei, Taiwan, ROC.
authors.forename: J J
authors.initials: JJ
authors.lastname: Chiu
authors.forename: B S
authors.initials: BS
authors.lastname: Wung
authors.forename: H J
authors.initials: HJ
authors.lastname: Hsieh
authors.forename: L W
authors.initials: LW
authors.lastname: Lo
authors.forename: D L
authors.initials: DL
authors.lastname: Wang
mesh_terms: D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D017874:Immediate-Early Proteins; D009569:Nitric Oxide / Q000494:pharmacology*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D013314:Stress, Mechanical; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D050807:ets-Domain Protein Elk-1; D018631:ras Proteins / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; C494112:ELK1 protein, human; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D010982:Platelet-Derived Growth Factor; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; C075278:platelet-derived growth factor A; D009569:Nitric Oxide; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D018631:ras Proteins