Wu Haibo, Wang Yuncan, Wang Xuechao, Li Ruyi, Yin Deyun
Department of Cardiology, The People's Hospital of Hebei Province, Shijiazhuang, Hebei 050000, China.
Department of Ultrasound, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, China.
Biochem Biophys Res Commun. 2017 Mar 4;484(2):304-310. doi: 10.1016/j.bbrc.2017.01.108. Epub 2017 Jan 24.
Evidence is emerging of a tight link between cardiomyocyte autophagy and cardiac hypertrophy (CH). Sustained exposure to stress leads CH to progress to heart failure. Several miRNAs have been described in heart failure, and miRNA-based therapeutic approaches are being pursued. Although microRNA-365 (miR-365) has been testified as a positive modulator of CH, the specific mechanism remains unclear. In the present study, we observed that miR-365 expression was up-regulated in hypertrophic cardiomyocytes both in vivo and in vitro, and was accompanied by dysregulation of autophagy. We found that miR-365 negatively modulates autophagy in hypertrophic cardiomyocytes by targeting Skp2. Overexpression of Skp2 promoted autophagy and rescued CH induced by Ang-II; conversely, Skp2 knockdown further inhibited autophagy and CH. Furthermore, we found that the activation of mammalian target of rapamycin (mTOR) signaling was regulated by Skp2 following Ang-II treatment, as indicated by the up-regulation of p-S6K and p-4EBP1 levels. The inactivation of mTOR by rapamycin completely abolished the Ang-II-induced inhibition of autophagy. In conclusion, our study provides substantial evidence that miR-365 and its target gene Skp2 play a functional role in CH and suggests the development of novel therapeutic options based on miR-365 and Skp2.
越来越多的证据表明心肌细胞自噬与心脏肥大(CH)之间存在紧密联系。持续暴露于应激会导致CH进展为心力衰竭。在心力衰竭中已经描述了几种 microRNA,基于 microRNA 的治疗方法也在不断探索。尽管 microRNA - 365(miR - 365)已被证明是 CH 的正向调节因子,但其具体机制仍不清楚。在本研究中,我们观察到 miR - 365 在体内和体外的肥大心肌细胞中表达均上调,并且伴有自噬失调。我们发现 miR - 365 通过靶向 Skp2 对肥大心肌细胞中的自噬起负向调节作用。Skp2 的过表达促进自噬并挽救了由 Ang - II 诱导的 CH;相反,Skp2 的敲低进一步抑制了自噬和 CH。此外,我们发现雷帕霉素处理后,Skp2 调节了哺乳动物雷帕霉素靶蛋白(mTOR)信号通路的激活,这表现为 p - S6K 和 p - 4EBP1 水平的上调。雷帕霉素使 mTOR 失活完全消除了 Ang - II 诱导的自噬抑制。总之,我们的研究提供了大量证据表明 miR - 365 及其靶基因 Skp2 在 CH 中发挥功能性作用,并提示基于 miR - 365 和 Skp2 开发新的治疗方案。