Mittal Manish, Nepal Saroj, Tsukasaki Yoshikazu, Hecquet Claudie M, Soni Dheeraj, Rehman Jalees, Tiruppathi Chinnaswamy, Malik Asrar B
From the Department of Pharmacology (M.M., S.N., Y.T., C.M.H., D.S., J.L., C.T., A.B.M.), and Department of Medicine, University of Illinois College of Medicine (J.L.).
Circ Res. 2017 Oct 13;121(9):1081-1091. doi: 10.1161/CIRCRESAHA.117.311747. Epub 2017 Aug 8.
TRPM2 (transient receptor potential melastatin-2) expressed in endothelial cells (ECs) is a cation channel mediating Ca entry in response to intracellular generation of adenosine diphosphoribose-the TRPM2 ligand.
Because polymorphonuclear neutrophils (PMN) interaction with ECs generates reactive oxygen species, we addressed the possible role of TRPM2 expressed in ECs in the mechanism of transendothelial migration of PMNs.
We observed defective PMN transmigration in response to lipopolysaccharide challenge in adult mice in which the EC expressed TRPM2 is conditionally deleted ( ). PMN interaction with ECs induced the entry of Ca in ECs via the EC-expressed TRPM2. Prevention of generation of adenosine diphosphoribose in ECs significantly reduced Ca entry in response to PMN activation of TRPM2 in ECs. PMNs isolated from mice significantly reduced Ca entry in ECs via TRPM2 as compared with wild-type PMNs and failed to induce PMN transmigration. Overexpression of the adenosine diphosphoribose insensitive TRPM2 mutant channel (C1008→A) in ECs suppressed the Ca entry response. Further, the forced expression of TRPM2 mutant channel (C1008→A) or silencing of poly ADP-ribose polymerase in ECs of mice prevented PMN transmigration.
Thus, endotoxin-induced transmigration of PMNs was secondary to TRPM2-activated Ca signaling and VE-cadherin phosphorylation resulting in the disassembly of adherens junctions and opening of the paracellular pathways. These results suggest blocking TRPM2 activation in ECs is a potentially important means of therapeutically modifying PMN-mediated vascular inflammation.
在内皮细胞（ECs）中表达的瞬时受体电位褪黑素2（TRPM2）是一种阳离子通道，可介导钙离子内流以响应细胞内二磷酸腺苷核糖（TRPM2配体）的生成。
由于多形核中性粒细胞（PMN）与ECs相互作用会产生活性氧，我们研究了ECs中表达的TRPM2在PMN跨内皮迁移机制中的可能作用。
我们观察到，在内皮细胞中条件性缺失TRPM2表达的成年小鼠中，脂多糖刺激后PMN迁移存在缺陷。PMN与ECs相互作用通过ECs中表达的TRPM2诱导钙离子进入ECs。抑制ECs中二磷酸腺苷核糖的生成可显著减少ECs中TRPM2被PMN激活后引起的钙离子内流。与野生型PMN相比，从TRPM2基因敲除小鼠中分离出的PMN通过TRPM2显著减少了ECs中的钙离子内流，并且无法诱导PMN迁移。在ECs中过表达对二磷酸腺苷核糖不敏感的TRPM2突变通道（C1008→A）可抑制钙离子内流反应。此外，在小鼠的ECs中强制表达TRPM2突变通道（C1008→A）或沉默聚ADP - 核糖聚合酶可阻止PMN迁移。
因此，内毒素诱导的PMN迁移继发于TRPM2激活的钙离子信号传导和血管内皮钙黏蛋白磷酸化，导致黏附连接的解体和细胞旁通路的开放。这些结果表明，阻断ECs中TRPM2的激活是治疗性调节PMN介导的血管炎症的潜在重要手段。
