BACKGROUND Our previous study showed that knockdown of long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) attenuated myocardial apoptosis in mouse acute myocardial infarction (AMI). This study aims to explore whether MALAT1 enhanced cardiomyocyte apoptosis via autophagy regulation and the underlying mechanisms of MALAT1 regulating autophagy. METHODS Cardiomyocytes were isolated from neonatal mice and then stimulated with hypoxia/reoxygenation (H/R) injury to mimic AMI. The autophagy level was assessed using GFP-LC3 immunofluorescence and western blot analysis of autophagy-related proteins. RNA pull-down and RNA immunoprecipitation (RIP) was performed to analyze the binding of MALAT1 and EZH2. Chromatin immunoprecipitation (ChIP) assay was performed to analyze the binding of TSC2 promoter and EZH2. The cell apoptosis was evaluated using TUNEL staining and western blot analysis of apoptosis-related proteins. RESULTS H/R injury increased MALAT1 expression in cardiomyocytes. Furthermore, MALAT1 overexpression inhibited, whereas MALAT1 knockdown enhanced the autophagy of cardiomyocytes. Moreover, MALAT1 overexpression recruited EZH2 to TSC2 promoter regions to elevate H3K27me3 and epigenetically inhibited TSC2 transcription. Importantly, TSC2 overexpression suppressed mTOR signaling and then activated the autophagy. Further results showed that MALAT1 inhibited proliferation and enhanced apoptosis of cardiomyocytes through inhibiting TSC2 and autophagy. CONCLUSION These findings demonstrate that the increased MALAT1 expression induced by H/R injury enhances cardiomyocyte apoptosis through autophagy inhibition by regulating TSC2-mTOR signaling.

中文翻译：

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长的非编码RNA MALAT1通过调节TSC2-mTOR信号传导的自噬抑制作用来增强心肌细胞的凋亡。

背景我们以前的研究表明，敲低长非编码RNA（lncRNA）转移相关的肺腺癌转录本1（MALAT1）可以减轻小鼠急性心肌梗塞（AMI）的心肌细胞凋亡。这项研究旨在探讨MALAT1是否通过自噬调节增强了心肌细胞的凋亡以及MALAT1调节自噬的潜在机制。方法从新生小鼠中分离心肌细胞，然后通过缺氧/复氧（H / R）损伤刺激以模拟AMI。使用GFP-LC3免疫荧光和自噬相关蛋白的蛋白质印迹分析来评估自噬水平。进行RNA下拉和RNA免疫沉淀（RIP）来分析MALAT1和EZH2的结合。进行染色质免疫沉淀（ChIP）分析以分析TSC2启动子和EZH2的结合。使用TUNEL染色和细胞凋亡相关蛋白的蛋白质印迹分析来评估细胞凋亡。结果H / R损伤增加了心肌细胞中MALAT1的表达。此外，MALAT1的过表达被抑制，而MALAT1的敲低则增强了心肌细胞的自噬。此外，MALAT1过表达将EZH2募集到TSC2启动子区域，以升高H3K27me3并在表观遗传上抑制TSC2转录。重要的是，TSC2过表达抑制mTOR信号传导，然后激活自噬。进一步的结果表明，MALAT1通过抑制TSC2和自噬来抑制心肌细胞的增殖并增强其凋亡。结论这些发现表明，H / R损伤诱导的MALAT1表达增加通过调节TSC2-mTOR信号转导的自噬抑制作用增强了心肌细胞的凋亡。