Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510080, China; Department of Pharmacy, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China.
Department of Pharmacy, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510655, China.
Free Radic Biol Med. 2019 Nov 1;143:288-299. doi: 10.1016/j.freeradbiomed.2019.08.018. Epub 2019 Aug 21.
Transient Receptor Potential Melastatin-2 (TRPM2) is a nonselective cation channel mediating Ca influx in response to oxidative stress. Given that insulin resistance-related endothelial dysfunction in obesity attributes to fatty-acid-induced reactive oxygen species (ROS) overproduction, in this study, we addressed the possible role of TRPM2 in obesity-related endothelial insulin resistance and the underlying mechanisms. Whole-cell patch clamp technique, intracellular Ca concentration measurement, western blot, vasorelaxation assay, and high-fat diet (HFD)-induced obese model were employed to assess the relationship between TRPM2 and endothelial insulin response. We found that both the expression and activity of TRPM2 were higher in endothelial cells of obese mice. Palmitate rose a cationic current in endothelial cells which was inhibited or enlarged by TRPM2 knockdown or overexpression. Silencing of TRPM2 remarkably improved insulin-induced endothelial Akt activation, nitric oxide synthase (eNOS) phosphorylation and nitric oxide (NO) production, while TRPM2 overexpression resulted in the opposite effects. Furthermore, TRPM2-mediated Ca entry, CaMKII activation and the following activation of PERK/ATF4/TRB3 cascade were involved in the mechanism of obesity or palmitate-induced endothelial insulin resistance. Notably, in vivo study, knockdown of TRPM2 with adeno-associated virus harboring short-hairpin RNA (shRNA) against TRPM2 alleviated endothelial insulin resistance and ameliorated endothelium-dependent vasodilatation in obese mice. Thus, these results suggest that TRPM2-activated Ca signaling is necessary to induce insulin resistance-related endothelial dysfunction in obesity. Downregulation or pharmacological inhibition of TRPM2 channels may lead to the development of effective drugs for treatment of endothelial dysfunction associated with oxidative stress state.
瞬时受体电位 M 型 2 通道（TRPM2）是一种非选择性阳离子通道，可介导细胞内钙离子内流，以响应氧化应激。鉴于肥胖相关的胰岛素抵抗内皮功能障碍归因于脂肪酸诱导的活性氧（ROS）过度产生，在这项研究中，我们探讨了 TRPM2 在肥胖相关的内皮胰岛素抵抗中的可能作用及其潜在机制。采用全细胞膜片钳技术、细胞内钙离子浓度测定、western blot、血管舒张测定和高脂肪饮食（HFD）诱导肥胖模型，评估 TRPM2 与内皮胰岛素反应之间的关系。我们发现肥胖小鼠内皮细胞中 TRPM2 的表达和活性均升高。棕榈酸增加了内皮细胞中的阳离子电流，TRPM2 的敲低或过表达可抑制或放大该电流。TRPM2 的沉默显著改善了胰岛素诱导的内皮 Akt 激活、一氧化氮合酶（eNOS）磷酸化和一氧化氮（NO）产生，而 TRPM2 的过表达则产生相反的效果。此外，TRPM2 介导的钙离子内流、钙调蛋白依赖性蛋白激酶 II（CaMKII）激活以及随后 PERK/ATF4/TRB3 级联的激活参与了肥胖或棕榈酸诱导的内皮胰岛素抵抗的机制。值得注意的是，体内研究表明，用携带针对 TRPM2 的短发夹 RNA（shRNA）的腺相关病毒进行 TRPM2 敲低可减轻肥胖小鼠的内皮胰岛素抵抗并改善内皮依赖性血管舒张。因此，这些结果表明，TRPM2 激活的钙信号对于诱导肥胖相关的胰岛素抵抗性内皮功能障碍是必要的。TRPM2 通道的下调或药理学抑制可能导致开发出针对与氧化应激状态相关的内皮功能障碍的有效药物。
