Surgical Department Cardiovascular Division, China Medical University Hospital, Taiwan, Republic of China.
Institute of Biochemistry, Microbiology and Immunology, Chung Shan Medical University, Taiwan, Republic of China.
Biofactors. 2021 May;47(3):386-402. doi: 10.1002/biof.1704. Epub 2021 Jan 27.
Acute myocardial infarction (AMI) and the following heart failure are public health problems faced all over the globe. The current study set out to investigate the role of B-cell lymphoma 6 (BCL-6) in cardiac protection after AMI. Initially, AMI mouse models and H9c2 cell oxygen-glucose deprivation (OGD) models were established. The cell models were transfected with the vectors containing oe-BCL-6, oe-EZH2, sh-EZH2, miR-34a mimic, and miR-34a inhibitor. RT-qPCR and Western blot analysis were applied to detect the expression patterns of microRNA-34a (miR-34a), BCL-6, enhancer of zeste homolog 2 (EZH2), and C1q tumor necrosis factor-related protein 9 (CTRP9) in the treated cell models. ChIP-qPCR and co-immunoprecipitation assay were performed to detect EZH2 enrichment and H3K27me3 levels in the miR-34a promoter region and the interaction between BCL-2 and EZH2, respectively. EdU staining, TUNEL staining, and flow cytometry were performed to detect cell proliferation and apoptosis, while ELISA was conducted to detect the oxidative stress levels. It was found that miR-34a was highly expressed in heart tissues of AMI models, while BCL-6 and EZH2 were poorly expressed. BCL-2 overexpression increased the recruitment of EZH2, upregulated H3K27me3 level in the miR-34a promoter region, and inhibited the miR-34a expression. Ctrp9, the downstream negative-regulatory molecule of miR-34a, was upregulated. Besides, miR-34a/CTRP9 expression changes were found to affect cardiomyocyte apoptosis, oxidation stress, and proliferation, and prevent myocardial injury in AMI mice. Our findings indicate that BCL-6 increases the level of H3K27me3 in the promoter region of miR-34a via EZH2 recruitment and CTRP9 upregulation, which inhibits the apoptosis of myocardial cells.
急性心肌梗死（AMI）和心力衰竭是全球面临的公共卫生问题。本研究旨在探讨 B 细胞淋巴瘤 6（BCL-6）在 AMI 后心脏保护中的作用。首先，建立 AMI 小鼠模型和 H9c2 细胞氧葡萄糖剥夺（OGD）模型。将含有 oe-BCL-6、oe-EZH2、sh-EZH2、miR-34a 模拟物和 miR-34a 抑制剂的载体转染细胞模型。应用 RT-qPCR 和 Western blot 分析检测处理细胞模型中 microRNA-34a（miR-34a）、BCL-6、增强子 of zeste 同源物 2（EZH2）和 C1q 肿瘤坏死因子相关蛋白 9（CTRP9）的表达模式。进行 ChIP-qPCR 和共免疫沉淀测定，以分别检测 miR-34a 启动子区域中 EZH2 的富集和 H3K27me3 水平，以及 BCL-2 和 EZH2 之间的相互作用。进行 EdU 染色、TUNEL 染色和流式细胞术检测细胞增殖和凋亡，同时进行 ELISA 检测氧化应激水平。结果发现，miR-34a 在 AMI 模型的心脏组织中高表达，而 BCL-6 和 EZH2 表达水平较低。BCL-2 的过表达增加了 EZH2 的募集，上调了 miR-34a 启动子区域的 H3K27me3 水平，并抑制了 miR-34a 的表达。miR-34a 的下游负调控分子 Ctrp9 上调。此外，miR-34a/CTRP9 表达变化影响心肌细胞凋亡、氧化应激和增殖，并防止 AMI 小鼠的心肌损伤。我们的研究结果表明，BCL-6 通过募集 EZH2 和上调 CTRP9 增加 miR-34a 启动子区域的 H3K27me3 水平，抑制心肌细胞凋亡。
