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ASSA13-03-39 Autophagy Induced by Ischemia/Reperfusion Protects Against Apopotosis by Downregulation of PI3K in Cardiac Myocytes
  1. Wang Luqiao1,
  2. Huang Chahua1,
  3. Huang Bo2,
  4. Wang Ling2,
  5. Cheng Xiaoshu1
  1. 1Department of Cardiovasology, the Second Affiliated Hospital of Nanchang University
  2. 2Department of clinical laboratory, the Second Affiliated Hospital of Nanchang University

Abstract

Objective The purpose of this study was to investigate the potential cardioprotection roles of autophagy induced by ischemia/reperfusion (I/R) against apopotosis in cardiac myocytes, and tries to clarify the effects of PI3K in this process.

Methods We employed simulated I/R of neonatal rat ventricular myocytes as an in vitro model of I/R injury to the heart. Cardiac myocytes were exposed to 3h hypoxia followed by 14h of reoxygenation, and during the reoxygenation cardiac myocytes were treated with 10mM 3-Methyladenine (3-MA) to inhibit autophagy or 50uM rapamycin to enhance autophagy. Then, we used real-time quantitative PCR (qPCR) to investigate the expression levels of Beclin 1, Bim, and caspase-3. Western blot analysis was used to examine variation in the expression of LC3-II/I (a marker of autophagy), Bim, caspase-3 and PI3K.

Results Our results demonstrated that the mRNA expression of Beclin 1 and the ratio of LC3II/I were significantly increased when myocytes followed sI/R (simulated I/R). Moreover, autophagy enhanced by rapamycin during sI/R, significantly reduced the mRNA expression of Bim and caspase-3, and downregulation of the protein expression level of Bim, caspase-3 and PI3K. In contrast, the mRNA expression of Bim and caspase-3 was increased significantly, and the expression of Bim, caspase-3 and PI3K elevated when 3-MA inhibited the activation of autophagy.

Conclusions Our results demonstrate that autophagy induced by sI/R constitutes a powerful and previously uncharacterized protective mechanism against apopotosis in cardiac myocytes via downregulating the pro-apopototic protein Bim and caspase-3, which is downregulated by PI3K. Rapamycin, the autophagic induction, can be used to reduced damage of fatal I/R injury via protecting against apoptosis, which may provide novel strategies for clinical treatment of I/R injury.

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