title: Cytochrome c oxidase is essential for copper-induced regression of cardiomyocyte hypertrophy.
abstract: Previous studies have shown that both copper (Cu) and vascular endothelial growth factor (VEGF) reduce the size of hypertrophic cardiomyocytes, but the Cu-induced regression is VEGF dependent. Studies in vivo have shown that hypertrophic cardiomyopathy is associated with a depression in cytochrome c oxidase (COX) activity, which could be involved in VEGF-mediated cellular function. The present study was undertaken to test the hypothesis that COX is a determinant factor in Cu-induced regression of cardiomyocyte hypertrophy. Primary cultures of neonatal rat cardiomyocytes were treated with phenylepherine (PE) at a final concentration of 100 microM in cultures for 48 h to induce cell hypertrophy. The hypertrophic cells were then treated with Cu sulfate at a final concentration of 5 microM in cultures for 24 h with a concomitant presence of PE to examine the effect of Cu on the regression of cardiomyocyte hypertrophy. Cell size changes were determined by flow cytometry, protein content, and molecular markers. Gene silencing was applied to study the effect of COX activity change on the regression of cardiomyocyte hypertrophy. PE treatment decreased COX activity in hypertrophic cardiomyocytes, and Cu addition restored the activity along with the regression of cell hypertrophy. Gene silencing using siRNA targeting COX-I significantly inhibited COX activity and blocked the Cu-induced regression of cell hypertrophy. VEGF alone also restored COX activity; but under the condition of COX inhibition by gene silencing, VEGF-induced regression of cell hypertrophy was suppressed. This study demonstrates that both Cu and VEGF can restore COX activity that is depressed in hypertrophic cardiomyocytes, and COX plays a determinant role in both Cu- and VEGF-induced regression of cardiomyocyte hypertrophy.
authors.affiliation: Regenerative Medicine Research Center and Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Zuo
authors.forename: Huiqi
authors.initials: H
authors.lastname: Xie
authors.forename: Daoyin
authors.initials: D
authors.lastname: Dong
authors.forename: Nenggang
authors.initials: N
authors.lastname: Jiang
authors.forename: Hongming
authors.initials: H
authors.lastname: Zhu
authors.forename: Y James
authors.initials: YJ
authors.lastname: Kang
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D006332:Cardiomegaly / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology; D048429:Cell Size; D002478:Cells, Cultured; D003300:Copper / Q000378:metabolism / Q000627:therapeutic use*; D051545:Cyclooxygenase 1 / Q000378:metabolism; D004032:Diet; D003576:Electron Transport Complex IV / Q000378:metabolism*; D005434:Flow Cytometry; D020868:Gene Silencing; D007150:Immunohistochemistry; D008297:Male; D032383:Myocytes, Cardiac / Q000201:enzymology* / Q000473:pathology*; D010656:Phenylephrine / Q000494:pharmacology; D034741:RNA, Small Interfering; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D000316:Adrenergic alpha-Agonists; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; D010656:Phenylephrine; D003300:Copper; D051545:Cyclooxygenase 1; D003576:Electron Transport Complex IV