Department of Emergency, The Ninth Hospital of Xi'an, Xi'an 710054, Shaanxi, China.
The First Department of Geriatrics, The Ninth Hospital of Xi'an, Xi'an 710054, Shaanxi, China.
Biosci Rep. 2020 Jan 31;40(1). doi: 10.1042/BSR20193482.
Ischemia/reperfusion (I/R) injury reduces cell proliferation, triggers inflammation, promotes cell apoptosis and necrosis, which are the leading reasons of morbidity and mortality in patients with cardiac disease. TGR5 is shown to express in hearts, but its functional role in I/R-induced myocardial injury is unclear. In the present study, we aimed to explore the underlying molecular mechanism of TGR5 in hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury in vitro. The results showed that TGR5 was significantly up-regulated in H9C2 (rat cardiomyocyte cells) and human cardiomyocytes (HCMs) after H/R. Overexpression of TGR5 significantly improved cell proliferation, alleviated apoptosis rate, the activities of caspase-3, cleaved caspases-3 and Bax protein expression levels, and increased Bcl-2 level. Overexpression of TGR5 significantly up-regulated ROS generation, stabilized the mitochondrial membrane potential (MMP), and reduced the concentration of intracellular Ca2+ as well as cytosolic translocation of mitochondrial cytochrome c (cyto-c). Meanwhile, overexpressed TGR5 also enhanced the mRNA and protein levels of interleukin (IL)-10, and decreased the mRNA and protein levels of IL-6 and tumor necrosis factor α (TNF-α). The shTGR5+H/R group followed opposite trends. In addition, overexpressed TGR5 induced an increase in the levels of p-AKT and p-GSK-3β. The protective effects of TGR5 were partially reversed by AKT inhibitor MK-2206. Taken together, these results suggest that TGR5 attenuates I/R-induced mitochondrial dysfunction and cell apoptosis as well as inflammation, and these protections may through AKT/GSK-3β pathway.
缺血/再灌注（I/R）损伤会降低细胞增殖，引发炎症，促进细胞凋亡和坏死，这是心脏病患者发病率和死亡率的主要原因。已经表明 TGR5 在心脏中表达，但它在 I/R 诱导的心肌损伤中的功能作用尚不清楚。在本研究中，我们旨在探讨 TGR5 在体外缺氧/复氧（H/R）诱导的心肌细胞损伤中的潜在分子机制。结果表明，H/R 后 H9C2（大鼠心肌细胞）和人心肌细胞（HCMs）中 TGR5 显著上调。TGR5 的过表达显著改善了细胞增殖，减轻了细胞凋亡率、caspase-3 的活性、裂解的 caspase-3 和 Bax 蛋白表达水平，并增加了 Bcl-2 水平。TGR5 的过表达还显著增加了 ROS 的产生，稳定了线粒体膜电位（MMP），并降低了细胞内 Ca2+浓度以及线粒体细胞色素 c（cyto-c）的胞质易位。同时，过表达的 TGR5 还增强了白细胞介素（IL）-10 的 mRNA 和蛋白水平，并降低了 IL-6 和肿瘤坏死因子-α（TNF-α）的 mRNA 和蛋白水平。shTGR5+H/R 组则呈现相反的趋势。此外，过表达的 TGR5 诱导了 p-AKT 和 p-GSK-3β 水平的增加。AKT 抑制剂 MK-2206 部分逆转了 TGR5 的保护作用。综上所述，这些结果表明，TGR5 减轻了 I/R 诱导的线粒体功能障碍和细胞凋亡以及炎症，这些保护作用可能通过 AKT/GSK-3β 通路。
