Nitric oxide inhibits endothelin-1-induced cardiomyocyte hypertrophy through cGMP-mediated suppression of extracellular-signal regulated kinase phosphorylation.
Cardiac hypertrophy is a compensatory mechanism in response to a variety of cardiovascular diseases. Recently, reactive oxygen species and nitric oxide (NO) have been demonstrated to be involved in the pathogenesis of atherosclerosis; however, the role of these free radicals in the development of cardiac hypertrophy remains unclear. In this study, we investigate NO modulation of cellular signaling in endothelin-1 (ET-1)-induced cardiomyocyte hypertrophy in culture. ET-1 treatment of cardiomyocytes increased constitutive NO synthase activity and induced NO production via the stimulation of ET-receptor subtype ET(B). Using Northern blot analysis and chloramphenicol acetyltransferase assay, we found that NO suppressed the ET-1-induced increase in c-fos mRNA level and promoter activity. In contrast, ET-1 stimulation of c-fos expression was augmented by depletion of endogenous NO generation with the addition of NO scavenger PTIO into cardiomyocytes. Cells cotransfected with the dominant negative and positive mutants of signaling molecules revealed that the Ras/Raf/extracellular-signal regulated kinase (ERK) signaling pathway is involved in ET-induced c-fos gene expression. Furthermore, NO directly inhibited ET-1-induced ERK phosphorylation and activation in a cGMP-dependent manner, indicating that NO modulates ET-1-induced c-fos expression via its inhibitory effect on ERK signaling pathway. The ET-1-stimulated activator protein-1 (AP-1) DNA binding activity and AP-1-mediated reporter activity were attenuated by NO. In addition, NO also significantly inhibited ET-1-stimulated promoter activity of hypertrophic marker gene beta-myosin heavy chain and the enhanced protein synthesis. Taken together, our findings provide the molecular basis of NO as a negative regulator in ET-1-induced cardiac hypertrophy.
Cheng
Tzu-Hurng
TH
Department of Medicine, Taipei Medical University-Wan Fang Medical Center, Taipei, Taiwan, R.O.C.
Shih
Neng-Lang
NL
Chen
Shin-Yee
SY
Lin
Jia-Wei
JW
Chen
Yen-Ling
YL
Chen
Cheng-Hsien
CH
Lin
Heng
H
Cheng
Ching-Feng
CF
Chiu
Wen-Ta
WT
Wang
Danny Ling
DL
Chen
Jin-Jer
JJ
D000818:Animals; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D019332:Endothelin-1 / Q000037:antagonists & inhibitors* / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D016762:Genes, fos; D006352:Heart Ventricles / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors / Q000502:physiology
D019332:Endothelin-1; D018808:Transcription Factor AP-1; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D048049:Extracellular Signal-Regulated MAP Kinases; D006152:Cyclic GMP