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  2. MicroRNA-223 protects neonatal rat cardiomyocytes and H9c2 cells from hypoxia-induced apoptosis and excessive autophagy via the Akt/mTOR pathway by targeting PARP-1

MicroRNA-223 protects neonatal rat cardiomyocytes and H9c2 cells from hypoxia-induced apoptosis and excessive autophagy via the Akt/mTOR pathway by targeting PARP-1

  • J Mol Cell Cardiol. 2018 May;118:133-146. doi: 10.1016/j.yjmcc.2018.03.018.
Xiaoxiao Liu 1 Yunfei Deng 1 Yifeng Xu 1 Wei Jin 2 Hongli Li 3
Affiliations

Affiliations

  • 1 Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
  • 2 Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China. Electronic address: jinwei225@yeah.net.
  • 3 Department of Cardiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China. Electronic address: dohonglili1234@163.com.
Abstract

Myocardial infarction (MI), characterized by interruption of blood and oxygen to myocardium, is a common yet fatal cardiovascular event that causes progressive damage to myocardial tissue and eventually leads to heart failure. Previous studies have shown increased expression of microRNA-223 (miR-223) in infarcted myocardial tissues of humans and in rat models of MI. However, the role of miR-223 in cell survival during MI has not been elucidated. Thus, we aimed to investigate whether miR-223 participates in the regulation of cardiac ischemia-induced injury and to elucidate the underlying mechanisms of this process. qRT-PCR revealed that miR-223 expression levels are significantly upregulated in the myocardial tissues of rats with post-MI heart failure and in hypoxia-treated neonatal rat cardiomyocytes (NRCMs) and H9c2 cells, which indicates that miR-223 may be associated with chronic ischemia. We also transfected NRCMs and H9c2 cells with miR-223 mimics or inhibitors in vitro, and the results revealed that increasing miR-223 expression protected cells from hypoxia-induced Apoptosis and excessive Autophagy, whereas decreasing miR-223 expression had contrasting effects. Further exploration of the mechanism showed that poly(ADP-ribose) polymerase 1 (PARP-1) is a target gene of miR-223 and that silencing PARP-1 prevented hypoxia-induced cell injury; additionally, silencing PARP-1 blocked the aggravated impact of miR-223 inhibitors. Thus, PARP-1 mediates the protective effects of miR-223 in hypoxia-treated cardiomyocytes. We also investigated the involvement of the Akt/mTOR pathway in the above phenomena. We found that miR-223 overexpression and PARP-1 silencing positively regulated the Akt/mTOR pathway and that treating cells with NVP-BEZ235 (BEZ235), a novel dual Akt/mTOR Inhibitor, could reverse the inhibitory effects of both the miR-223 mimics and PARP-1 siRNA on hypoxia-induced Apoptosis and Autophagy. Taken together, our findings showed that miR-223 protects NRCMs and H9c2 cells from hypoxia-induced Apoptosis and excessive Autophagy via the Akt/mTOR pathway by targeting PARP-1; thus, miR-223 may be a potential target in the treatment of MI in the future.

Keywords

Akt/mTOR signaling pathway; Apoptosis; Autophagy; MicroRNA-223; Myocardial infarction; PARP-1.

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