Department of Cardiovascular, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, P.R. China.
Biochem Cell Biol. 2020 Apr;98(2):130-136. doi: 10.1139/bcb-2019-0062. Epub 2020 Jan 27.
Induction of autophagy promotes cardiomyocyte survival and confers a cardioprotective effect on acute myocardial infarction (AMI). Our previous study showed that knockdown of long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) attenuated myocardial apoptosis in mouse AMI. Herein, this study further investigated whether the mechanisms by which MALAT1 enhanced cardiomyocyte apoptosis involved the autophagy regulation. To address this, cardiomyocytes were isolated from neonatal mice and then stimulated with hypoxia/reoxygenation (H/R) injury to mimic AMI. The cell apoptosis was evaluated using TUNEL staining and Western blot analysis of apoptosis-related proteins. The autophagy level was assessed using GFP-LC3 immunofluorescence and Western blot analysis of autophagy-related proteins. The results showed that H/R injury increased MALAT1 expression. Furthermore, MALAT1 overexpression significantly enhanced apoptosis and regulated autophagy of cardiomyocytes, whereas MALAT1 knockdown exerted the opposite effect. Moreover, rapamycin (an autophagy activator) effectively attenuated the MALAT1-mediated enhancement of cardiomyocyte apoptosis. Overall, our findings demonstrated that the increased MALAT1 expression induced by H/R injury enhances cardiomyocyte apoptosis, at least in part, through autophagy modulation.
自噬的诱导可促进心肌细胞存活，并对急性心肌梗死（AMI）产生心脏保护作用。我们之前的研究表明，长链非编码 RNA（lncRNA）转移相关肺腺癌转录本 1（MALAT1）的敲低可减轻小鼠 AMI 中的心肌细胞凋亡。在此，本研究进一步探讨了 MALAT1 增强心肌细胞凋亡的机制是否涉及自噬调节。为此，从小鼠分离心肌细胞，然后用缺氧/复氧（H/R）损伤刺激以模拟 AMI。通过 TUNEL 染色和凋亡相关蛋白的 Western blot 分析评估细胞凋亡。通过 GFP-LC3 免疫荧光和自噬相关蛋白的 Western blot 分析评估自噬水平。结果表明，H/R 损伤增加了 MALAT1 的表达。此外，MALAT1 的过表达显著增强了心肌细胞的凋亡并调节了自噬，而 MALAT1 的敲低则产生了相反的效果。此外，雷帕霉素（一种自噬激活剂）可有效减轻 MALAT1 介导的心肌细胞凋亡增强作用。总的来说，我们的研究结果表明，H/R 损伤引起的 MALAT1 表达增加至少部分通过自噬调节来增强心肌细胞凋亡。
