Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, California.
Division of Cardiothoracic Surgery, Department of Surgery, University of California, San Diego, California.
Am J Physiol Cell Physiol. 2022 Oct 1;323(4):C959-C973. doi: 10.1152/ajpcell.00313.2022. Epub 2022 Aug 15.
Mechanosensitive cation channels and Ca influx through these channels play an important role in the regulation of endothelial cell functions. Transient receptor potential canonical channel 6 (TRPC6) is a diacylglycerol-sensitive nonselective cation channel that forms receptor-operated Ca channels in a variety of cell types. Piezo1 is a mechanosensitive cation channel activated by membrane stretch and shear stress in lung endothelial cells. In this study, we report that TRPC6 and Piezo1 channels both contribute to membrane stretch-mediated cation currents and Ca influx or increase in cytosolic-free Ca concentration ([Ca]) in human pulmonary arterial endothelial cells (PAECs). The membrane stretch-mediated cation currents and increase in [Ca] in human PAECs were significantly decreased by GsMTX4, a blocker of Piezo1 channels, and by BI-749327, a selective blocker of TRPC6 channels. Extracellular application of 1-oleoyl-2-acetyl--glycerol (OAG), a membrane permeable analog of diacylglycerol, rapidly induced whole cell cation currents and increased [Ca] in human PAECs and human embryonic kidney (HEK)-cells transiently transfected with the human gene. Furthermore, membrane stretch with hypo-osmotic or hypotonic solution enhances the cation currents in -transfected HEK cells. In HEK cells transfected with the gene, however, OAG had little effect on the cation currents, but membrane stretch significantly enhanced the cation currents. These data indicate that, while both TRPC6 and Piezo1 are involved in generating mechanosensitive cation currents and increases in [Ca] in human PAECs undergoing mechanical stimulation, only TRPC6 (but not Piezo1) is sensitive to the second messenger diacylglycerol. Selective blockers of these channels may help develop novel therapies for mechanotransduction-associated pulmonary vascular remodeling in patients with pulmonary arterial hypertension.
机械敏感性阳离子通道和这些通道中的钙离子内流在调节内皮细胞功能方面发挥着重要作用。瞬时受体电位经典通道 6（TRPC6）是一种二酰基甘油敏感的非选择性阳离子通道，它在多种细胞类型中形成受体操纵的钙离子通道。Piezo1 是一种机械敏感性阳离子通道，在肺内皮细胞中受膜拉伸和切应力激活。在这项研究中，我们报告 TRPC6 和 Piezo1 通道都有助于膜拉伸介导的阳离子电流和钙离子内流或增加人肺动脉内皮细胞（PAEC）中的细胞内游离钙浓度（[Ca]）。膜拉伸介导的阳离子电流和人 PAEC 中 [Ca]的增加，通过 Piezo1 通道的阻断剂 GsMTX4 和 TRPC6 通道的选择性阻断剂 BI-749327 显著减少。1-油酰基-2-乙酰基-sn-甘油（OAG），一种二酰基甘油的膜通透类似物，细胞外应用可迅速诱导全细胞阳离子电流，并增加人 PAEC 和瞬时转染人 基因的人胚肾（HEK）细胞中的 [Ca]。此外，低渗或低渗溶液的膜拉伸增强了 -转染的 HEK 细胞中的阳离子电流。然而，在转染了 基因的 HEK 细胞中，OAG 对阳离子电流几乎没有影响，但膜拉伸显著增强了阳离子电流。这些数据表明，虽然 TRPC6 和 Piezo1 都参与了机械刺激下人 PAEC 中机械敏感性阳离子电流和 [Ca]的增加，但只有 TRPC6（而不是 Piezo1）对第二信使二酰基甘油敏感。这些通道的选择性阻断剂可能有助于为肺动脉高压患者的机械转导相关肺血管重塑开发新的治疗方法。
