Acta Biochim Biophys Sin (Shanghai). 2022 Apr 25;54(4):463-473. doi: 10.3724/abbs.2022037.
NORAD is a newly identified long non-coding RNA (lncRNA) that plays an important role in cancers. NORAD has been found to be highly expressed in the mouse model of acute myocardial infarction (AMI). However, the role of NORAD in the regulation of AMI remains unknown. In the present study, we aimed to investigate the function of NORAD in AMI and explore the potential regulatory mechanisms. A mouse model of AMI was established and NORAD was knocked-down. The infarcted size of heart tissues and the cardiac function were evaluated. In addition, two cardiomyocyte cell lines were treated with hypoxia/re-oxygenation (H/R) to mimic AMI . Luciferase reporter assay, RNA pull-down assay, fluorescence hybridization, qRT-PCR, and western blot analysis were performed. Apoptotic cells and the levels of L-lactate dehydrogenase (LDH) and malondialdehyde (MDA) were detected. Our results show that downregulation of NORAD efficiently attenuates heart damage in the AMI mouse model. NORAD interacts with miR-22-3p. Knock-down of NORAD inhibits H/R-induced cell apoptosis and reduces LDH and MDA levels, while its effects are abolished by miR-22-3p inhibitor. MiR-22-3p interacts with PTEN and inhibits its expression. Overexpression of miR-22-3p inhibits H/R-induced cell apoptosis and reduces LDH and MDA levels, while its effects are abolished by overexpression of PTEN. Finally, overexpression of NORAD inhibits the AKT/mTOR signaling pathway, and its effects are attenuated by overexpression of miR-22-3p. Taken together, our study reveals that NORAD promotes the progression of AMI by regulating the miR-22-3p/PTEN axis, and the AKT/mTOR signaling may also be involved in the regulatory processes.
NORAD 是一种新鉴定的长链非编码 RNA（lncRNA），在癌症中发挥重要作用。NORAD 在急性心肌梗死（AMI）的小鼠模型中被发现高度表达。然而，NORAD 在调节 AMI 中的作用尚不清楚。在本研究中，我们旨在研究 NORAD 在 AMI 中的功能，并探讨潜在的调节机制。建立了 AMI 的小鼠模型并敲低 NORAD。评估心脏组织的梗死面积和心功能。此外，用缺氧/复氧（H/R）处理两种心肌细胞系模拟 AMI。进行荧光素酶报告基因检测、RNA 下拉实验、荧光杂交、qRT-PCR 和 Western blot 分析。检测凋亡细胞以及 L-乳酸脱氢酶（LDH）和丙二醛（MDA）的水平。我们的结果表明，下调 NORAD 可有效减轻 AMI 小鼠模型中的心脏损伤。NORAD 与 miR-22-3p 相互作用。敲低 NORAD 可抑制 H/R 诱导的细胞凋亡并降低 LDH 和 MDA 水平，而 miR-22-3p 抑制剂可消除其作用。miR-22-3p 与 PTEN 相互作用并抑制其表达。过表达 miR-22-3p 可抑制 H/R 诱导的细胞凋亡并降低 LDH 和 MDA 水平，而过表达 PTEN 可消除其作用。最后，过表达 NORAD 抑制 AKT/mTOR 信号通路，而过表达 miR-22-3p 可减弱其作用。总之，我们的研究表明，NORAD 通过调节 miR-22-3p/PTEN 轴促进 AMI 的进展，AKT/mTOR 信号通路也可能参与调节过程。
