Role of mitogen-activated protein kinase pathway in reactive oxygen species-mediated endothelin-1-induced beta-myosin heavy chain gene expression and cardiomyocyte hypertrophy.
Endothelin-1 (ET-1) has been found to increase cardiac beta-myosin heavy chain (beta-MyHC) gene expression and induce hypertrophy in cardiomyocytes. ET-1 has been demonstrated to increase intracellular reactive oxygen species (ROS) in cardiomyocytes. The exact molecular mechanism by which ROS regulate ET-1-induced beta-MyHC gene expression and hypertrophy in cardiomyocytes, however, has not yet been fully described. We aim to elucidate the molecular regulatory mechanism of ROS on ET-1-induced beta-MyHC gene expression and hypertrophic signaling in neonatal rat cardiomyocytes. Following stimulation with ET-1, cultured neonatal rat cardiomyocytes were examined for 3H-leucine incorporation and beta-MyHC promoter activities. The effects of antioxidant pretreatment on ET-1-induced cardiac hypertrophy and mitogen-activated protein kinase (MAPKs) phosphorylation were studied to elucidate the redox-sensitive pathway in cardiomyocyte hypertrophy and beta-MyHC gene expression. ET-1 increased 3H-leucine incorporation and beta-MyHC promoter activities, which were blocked by the specific ET(A) receptor antagonist BQ-485. Antioxidants significantly reduced ET-1-induced 3H-leucine incorporation, beta-MyHC gene promoter activities and MAPK (extracellular signal-regulated kinase, p38, and c-Jun NH2 -terminal kinase) phosphorylation. Both PD98059 and SB203580 inhibited ET-1-increased 3H-leucine incorporation and beta-MyHC promoter activities. Co-transfection of the dominant negative mutant of Ras, Raf, and MEK1 decreased the ET-1-induced beta-MyHC promoter activities, suggesting that the Ras-Raf-MAPK pathway is required for ET-1 action. Truncation analysis of the beta-MyHC gene promoter showed that the activator protein-2 (AP-2)/specificity protein-1 (SP-1) binding site(s) were(was) important cis-element(s) in ET-1-induced beta-MyHC gene expression. Moreover, ET-1-induced AP-2 and SP-1 binding activities were also inhibited by antioxidant. These data demonstrate the involvement of ROS in ET-1-induced hypertrophic responses and beta-MyHC expression. ROS mediate ET-1-induced activation of MAPK pathways, which culminates in hypertrophic responses and beta-MyHC expression.
Cheng
Tzu-Hurng
TH
Department of Medicine, Taipei Medical University-Wan Fang Hospital, Taiwan.
Shih
Neng-Lang
NL
Chen
Cheng-Hsien
CH
Lin
Heng
H
Liu
Ju-Chi
JC
Chao
Hung-Hsing
HH
Liou
Jer-Young
JY
Chen
Yen-Ling
YL
Tsai
Hsing-Wen
HW
Chen
Yee-Shiuan
YS
Cheng
Ching-Feng
CF
Chen
Jin-Jer
JJ
D000818:Animals; D000831:Animals, Newborn; D024722:Cardiac Myosins; D002478:Cells, Cultured; D019332:Endothelin-1 / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D006984:Hypertrophy; D020935:MAP Kinase Signaling System / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000473:pathology* / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000235:genetics* / Q000378:metabolism; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D044022:Receptor, Endothelin A / Q000378:metabolism
D019332:Endothelin-1; D004791:Enzyme Inhibitors; C501641:MYH7 protein, human; D017382:Reactive Oxygen Species; D044022:Receptor, Endothelin A; D024722:Cardiac Myosins; D018995:Myosin Heavy Chains