Medical Center, Hainan General Hospital (Hainan Affiliated Hospital of Hainan Medical University), Haikou 570311, Hainan Province, P.R. China.
Department of Otorhinolaryngology Head and Neck Surgery, Hainan General Hospital (Hainan Affiliated Hospital of Hainan Medical University), Haikou 570311, Hainan Province, P.R. China.
Toxicol Appl Pharmacol. 2021 Dec 15;433:115782. doi: 10.1016/j.taap.2021.115782. Epub 2021 Nov 2.
Epigallocatechin gallate (EGCG) has attracted increasing attention due to its beneficial effect on cardiovascular health. The aim of this study was to investigate the underlying mechanism by which EGCG protects against myocardial ischaemia/reperfusion injury (I/RI).
Murine myocardial I/RI and HO-induced cardiomyocyte injury models were established to evaluate the therapeutic effects of EGCG. In the myocardial I/RI mouse model, the echocardiographic parameters of ejection fraction (EF) and fraction shortening (FS) levels, infarct size, histological evaluation and transmission electron microscopy (TEM) were used to evaluate cardiac tissue damage and autophagy. MTT assays, TUNEL staining, flow cytometry and immunofluorescence (IF) were used to monitor cell viability, apoptosis and autophagy in vitro. qRT-PCR and western blotting were used to determine the mRNA and protein levels of key molecules, respectively. The epigenetic regulation of DUSP5 was assessed via RNA immunoprecipitation (RIP), RNA pull-down and chromatin immunoprecipitation (ChIP) assays.
EGCG significantly improved cardiac function, reduced infarct size, enhanced cell viability and inhibited autophagic activity in both myocardial I/RI mouse models and HO-induced cardiomyocyte injury models. Moreover, EGCG suppressed HO- or myocardial I/R-increased Gm4419 expression, and Gm4419 overexpression dramatically abolished EGCG-mediated protective effects against myocardial I/RI. Mechanistically, Gm4419 epigenetically suppressed DUSP5 by recruiting EZH2, thus activating ERK1/2 pathway-mediated autophagy. Furthermore, the in vivo experiments further verified that the Gm4419-mediated disruptive effects of EGCG on myocardial I/RI were potentiated by DUSP5 knockdown but attenuated by DUSP5 overexpression.
In conclusion, our findings demonstrated that EGCG protected against myocardial I/RI by modulating Gm4419/DUSP5/ERK1/2-mediated autophagy.
表没食子儿茶素没食子酸酯（EGCG）因其对心血管健康的有益作用而受到越来越多的关注。本研究旨在探讨 EGCG 防治心肌缺血/再灌注损伤（I/RI）的潜在机制。
建立了小鼠心肌 I/RI 和 HO 诱导的心肌细胞损伤模型，以评估 EGCG 的治疗效果。在心肌 I/RI 小鼠模型中，通过超声心动图评估射血分数（EF）和缩短分数（FS）水平、梗死面积、组织学评估和透射电子显微镜（TEM）评估心脏组织损伤和自噬。MTT 测定、TUNEL 染色、流式细胞术和免疫荧光（IF）用于监测体外细胞活力、细胞凋亡和自噬。qRT-PCR 和 Western blot 分别用于确定关键分子的 mRNA 和蛋白水平。通过 RNA 免疫沉淀（RIP）、RNA 下拉和染色质免疫沉淀（ChIP）实验评估 DUSP5 的表观遗传调控。
EGCG 显著改善了心脏功能，减少了心肌 I/RI 小鼠模型和 HO 诱导的心肌细胞损伤模型中的梗死面积，提高了细胞活力并抑制了自噬活性。此外，EGCG 抑制了 HO 或心肌 I/R 增加的 Gm4419 表达，而过表达 Gm4419 则明显消除了 EGCG 对心肌 I/RI 的保护作用。机制上，Gm4419 通过募集 EZH2 抑制 DUSP5 的表达，从而激活 ERK1/2 通路介导的自噬。此外，体内实验进一步验证了 Gm4419 介导的 EGCG 对心肌 I/RI 的破坏作用被 DUSP5 敲低增强，但被 DUSP5 过表达减弱。
总之，我们的研究结果表明，EGCG 通过调节 Gm4419/DUSP5/ERK1/2 介导的自噬来保护心肌免受 I/RI。
