From the Department of Pharmacology and the Center for Lung and Vascular Biology (C.M.H., M.Z., M.M., S.M.V., A.D., X.G., M.G.B., A.B.M.) and Section of Cardiology (M.G.B.), College of Medicine, University of Illinois, Chicago.
Circ Res. 2014 Jan 31;114(3):469-79. doi: 10.1161/CIRCRESAHA.114.302414. Epub 2013 Dec 11.
Oxidants generated by activated endothelial cells are known to induce apoptosis, a pathogenic feature of vascular injury and inflammation from multiple pathogeneses. The melastatin-family transient receptor potential 2 (TRPM2) channel is an oxidant-sensitive Ca2+ permeable channel implicated in mediating apoptosis; however, the mechanisms of gating of the supranormal Ca2+ influx required for initiating of apoptosis are not understood.
Here, we addressed the role of TRPM2 and its interaction with the short splice variant TRPM2 short variant (TRPM2-S) in mediating the Ca2+ entry burst required for induction of endothelial cell apoptosis.
We observed that TRPM2-S was basally associated with TRPM2 in the endothelial plasmalemma, and this interaction functioned to suppress TRPM2-dependent Ca2+ gating constitutively. Reactive oxygen species production in endothelial cells or directly applying reactive oxygen species induced protein kinase C-α activation and phosphorylation of TRPM2 at Ser 39. This in turn stimulated a large entry of Ca2+ and activated the apoptosis pathway. A similar TRPM2-dependent endothelial apoptosis mechanism was seen in intact vessels. The protein kinase C-α-activated phosphoswitch opened the TRPM2 channel to allow large Ca2+ influx by releasing TRPM2-S inhibition of TRPM2, which in turn activated caspase-3 and cleaved the caspase substrate poly(ADP-ribose) polymerase.
Here, we describe a fundamental mechanism by which activation of the trp superfamily TRPM2 channel induces apoptosis of endothelial cells. The signaling mechanism involves reactive oxygen species-induced protein kinase C-α activation resulting in phosphorylation of TRPM2-S that allows enhanced TRPM2-mediated gating of Ca2+ and activation of the apoptosis program. Strategies aimed at preventing the uncoupling of TRPM2-S from TRPM2 and subsequent Ca2+ gating during oxidative stress may mitigate endothelial apoptosis and its consequences in mediating vascular injury and inflammation.
已知激活的内皮细胞产生的氧化剂可诱导细胞凋亡，这是多种发病机制导致的血管损伤和炎症的一个发病特征。瞬时受体电位 M 型 2（TRPM2）通道是一种氧化剂敏感的 Ca2+ 渗透性通道，与介导细胞凋亡有关；然而，对于启动细胞凋亡所需的超常 Ca2+ 内流的门控机制尚不清楚。
本研究旨在探讨 TRPM2 及其与短剪接变体 TRPM2 短变体（TRPM2-S）的相互作用在介导内皮细胞凋亡所需的 Ca2+ 内流爆发中的作用。
我们观察到 TRPM2-S 在内皮质膜中与 TRPM2 基础相关，这种相互作用作用于持续抑制 TRPM2 依赖性 Ca2+ 门控。内皮细胞中活性氧物质的产生或直接应用活性氧物质可诱导蛋白激酶 C-α 的激活和 TRPM2 在丝氨酸 39 位的磷酸化。这反过来又刺激了大量 Ca2+ 的内流，并激活了凋亡途径。在完整的血管中也观察到类似的 TRPM2 依赖性内皮细胞凋亡机制。蛋白激酶 C-α 激活的磷酸开关打开 TRPM2 通道，通过释放 TRPM2-S 抑制 TRPM2，从而允许大量 Ca2+ 内流，进而激活半胱天冬酶-3 并切割半胱天冬酶底物多聚（ADP-核糖）聚合酶。
本研究描述了 trp 超家族 TRPM2 通道激活诱导内皮细胞凋亡的基本机制。该信号机制涉及活性氧物质诱导的蛋白激酶 C-α 激活，导致 TRPM2-S 的磷酸化，从而增强 TRPM2 介导的 Ca2+ 门控和凋亡程序的激活。旨在防止在氧化应激过程中 TRPM2-S 与 TRPM2 解偶联以及随后的 Ca2+ 门控的策略可能减轻内皮细胞凋亡及其在介导血管损伤和炎症中的后果。
