MicroRNAs are dynamically regulated in hypertrophic hearts, and miR-199a is essential for the maintenance of cell size in cardiomyocytes.
Cardiac hypertrophy, which is characterized by an increase in cell size and reactivation of fetal genes, occurs as an adaptive response to diverse forms of stress and often results in heart failure and sudden death. Growing evidence indicates that microRNAs (miRNAs) are involved in cardiac hypertrophy, but the function of these miRNAs remains elusive. Here, using real time PCR analysis, we showed that several miRNAs were dynamically regulated in the rat hypertrophic hearts and miR-199a was up-regulated by 10-fold in hypertrophic hearts after abdominal aorta constriction for 12 weeks. With tissue profiling analysis, we showed that miR-199a was predominantly expressed in cardiomyocytes, but was also faintly detected in cardiac fibroblasts. To investigate whether miR-199a was involved in cardiac hypertrophy, both over-expression and knockdown of miR-199a were performed in cultured cardiomyocytes. Over-expression of miR-199a in cardiomyocytes increased the cell size as measured by cell surface area, and also reduced the mRNA expression level of alpha-myosin heavy chain. In accordance, knockdown of endogenous miR-199a in cardiomyocytes reduced the cell size. Down-regulation of miR-199a also attenuated the phenylephrine-induced increase of cell size. Furthermore, bioinformatic algorithms were used to predict the potential targets of miR-199a in cardiac hypertrophy, and hypoxia-inducible factor 1 alpha was confirmed by the luciferase reporter assay to be a potential target of miR-199a. Taken together, our results demonstrated that miR-199a, which was predominantly expressed in cardiomyocytes, was essential for the maintenance of cell size of cardiomyocytes and might play a role in the regulation of cardiac hypertrophy.
Song
Xiao-Wei
XW
Department of Cardiology, Changhai Hospital, Shanghai, China.
Li
Qing
Q
Lin
Li
L
Wang
Xiao-Chen
XC
Li
Dong-Feng
DF
Wang
Guo-Kun
GK
Ren
An-Jing
AJ
Wang
Yan-Rong
YR
Qin
Yong-Wen
YW
Yuan
Wen-Jun
WJ
Jing
Qing
Q
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D006332:Cardiomegaly / Q000378:metabolism*; D048429:Cell Size; D015536:Down-Regulation; D017353:Gene Deletion; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
D000316:Adrenergic alpha-Agonists; C552425:MIRN199 microRNA, rat; D035683:MicroRNAs; D010656:Phenylephrine