Table2_PIEZO1 Ion Channel Mediates Ionizing Radiation-Induced Pulmonary Endothelial Cell Ferroptosis via Ca2+/Calpain/VE-Cadherin Signaling.XLSX

Pulmonary endothelial cell dysfunction plays an important role in ionizing radiation (IR)-induced lung injury. Whether pulmonary endothelial cell ferroptosis occurs after IR and what are the underlying mechanisms remain elusive. Here, we demonstrate that 15-Gy IR induced ferroptosis characterized by lethal accumulation of reactive oxygen species (ROS), lipid peroxidation, mitochondria shrinkage, and decreased glutathione peroxidase 4 (GPX4) and SLC7A11 expression in pulmonary endothelial cells. The phenomena could be mimicked by Yoda1, a specific activator of mechanosensitive calcium channel PIEZO1. PIEZO1 protein expression was upregulated by IR in vivo and in vitro. The increased PIEZO1 expression after IR was accompanied with increased calcium influx and increased calpain activity. The effects of radiation on lung endothelial cell ferroptosis was partly reversed by inhibition of PIEZO1 activity using the selective inhibitor GsMTx4 or inhibition of downstreaming Ca2+/calpain signaling using PD151746. Both IR and activation of PIEZO1 led to increased degradation of VE-cadherin, while PD151746 blocked these effects. VE-cadherin knockdown by specific siRNA causes ferroptosis-like phenomena with increased ROS and lipid peroxidation in the lung endothelial cells. Overexpression of VE-cadherin partly recused the ferroptosis caused by IR or PIEZO1 activation as supported by decreased ROS production, lipid peroxidation and mitochondria shrinkage compared to IR or PIEZO1 activation alone. In summary, our study reveals a previously unrecognized role of PIEZO1 in modulating ferroptosis, providing a new target for future mitigation of radiation-induced lung injury.

肺泡内皮细胞功能障碍在电离辐射（IR）诱导的肺损伤中扮演着至关重要的角色。电离辐射后肺泡内皮细胞是否会发生铁死亡及其潜在机制仍是一个未解之谜。本研究揭示了15 Gy电离辐射诱导的铁死亡特征，表现为细胞内活性氧（ROS）的致命性积累、脂质过氧化、线粒体缩小以及肺泡内皮细胞中谷胱甘肽过氧化物酶4（GPX4）和SLC7A11表达的降低。这一现象可以被Yoda1（一种机械敏感性钙通道PIEZO1的特异性激活剂）所模拟。PIEZO1蛋白的表达在体内和体外经电离辐射后均上调。电离辐射后PIEZO1表达的增加伴随着钙离子内流的增加和钙蛋白酶活性的增强。使用选择性抑制剂GsMTx4抑制PIEZO1活性或使用PD151746抑制下游的Ca2+/钙蛋白酶信号通路可以部分逆转辐射对肺内皮细胞铁死亡的影响。电离辐射和PIEZO1的激活均导致VE-cadherin降解增加，而PD151746可以阻断这些效应。通过特异性siRNA敲低VE-cadherin可导致肺泡内皮细胞发生铁死亡样现象，表现为ROS和脂质过氧化的增加。与单独的电离辐射或PIEZO1激活相比，VE-cadherin的过表达部分缓解了由电离辐射或PIEZO1激活引起的铁死亡，这通过降低ROS产生、脂质过氧化和线粒体缩小得以证实。总之，本研究揭示了PIEZO1在调节铁死亡中的先前未认识到的作用，为未来减轻辐射诱导的肺损伤提供了新的靶点。