The muscle-specific microRNAs miR-1 and miR-133 produce opposing effects on apoptosis by targeting HSP60, HSP70 and caspase-9 in cardiomyocytes.
The microRNAs miR-1 and miR-133 are preferentially expressed in cardiac and skeletal muscles and have been shown to regulate differentiation and proliferation of these cells. We report here a novel aspect of cellular function of miR-1 and miR-133 regulation of cardiomyocyte apoptosis. miR-1 and miR-133 produced opposing effects on apoptosis, induced by oxidative stress in H9c2 rat ventricular cells, with miR-1 being pro-apoptotic and miR-133 being anti-apoptotic. miR-1 level was significantly increased in response to oxidative stress. We identified single target sites for miR-1 only, in the 3'-untranslated regions of the HSP60 and HSP70 genes, and multiple putative target sites for miR-133 throughout the sequence of the caspase-9 gene. miR-1 reduced the levels of HSP60 and HSP70 proteins without changing their transcript levels, whereas miR-133 did not affect HSP60 and HSP70 expression at all. By contrast, miR-133 repressed caspase-9 expression at both the protein and mRNA levels. The post-transcriptional repression of HSP60 and HSP70 and caspase-9 was further confirmed by luciferase reporter experiments. Our results indicate that miR-1 and miR-133 are involved in regulating cell fate with increased miR-1 and/or decreased miR-133 levels favoring apoptosis and decreased miR-1 and/or miR-133 levels favoring survival. Post-transcriptional repression of HSP60 and HSP70 by miR-1 and of caspase-9 by miR-133 contributes significantly to their opposing actions.
Xu
Chaoqian
C
Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, Harbin, Heilongjiang 150086, People's Republic of China.
Lu
Yanjie
Y
Pan
Zhenwei
Z
Chu
Wenfeng
W
Luo
Xiaobin
X
Lin
Huixian
H
Xiao
Jiening
J
Shan
Hongli
H
Wang
Zhiguo
Z
Yang
Baofeng
B
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001483:Base Sequence; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D018834:Chaperonin 60 / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006321:Heart / Q000502:physiology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000502:physiology; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000502:physiology*; D016877:Oxidants / Q000378:metabolism; D018384:Oxidative Stress; D051381:Rats
D018834:Chaperonin 60; D018840:HSP70 Heat-Shock Proteins; D035683:MicroRNAs; D016877:Oxidants; D006861:Hydrogen Peroxide; D053148:Caspase 3; D053453:Caspase 9