Homocysteine Causes Endothelial Dysfunction via Inflammatory Factor-Mediated Activation of Epithelial Sodium Channel (ENaC)

• Published in: Frontiers in cell and developmental biology Vol. 9; p. 672335
• Main Authors: Liang, Chen, Wang, Qiu-Shi, Yang, Xu, Zhu, Di, Sun, Yu, Niu, Na, Yao, Jie, Dong, Bi-Han, Jiang, Shuai, Tang, Liang-Liang, Lou, Jie, Yu, Chang-Jiang, Shao, Qun, Wu, Ming-Ming, Zhang, Zhi-Ren
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 17.06.2021
• Subjects: Cell and Developmental Biology; endothelial epithelial sodium channel; hyperhomocysteinemia; inflammation and cyclooxygenase-2; reactive oxygen species; vascular dysfunction; hyperhomocysteinemia; vascular dysfunction; inflammation and cyclooxygenase-2; endothelial epithelial sodium channel; reactive oxygen species
• ISSN: 2296-634X; 2296-634X
• DOI: 10.3389/fcell.2021.672335

Hyperhomocysteinemia (HHcy) causes cardiovascular diseases via regulating inflammatory responses. We investigated whether and how the epithelial sodium channel (ENaC), a recently identified ion channel in endothelial cells, plays a role in HHcy-induced endothelial dysfunction. Cell-attached patch-clamp recording in acute split-open aortic endothelial cells, western blot, confocal imaging, and wire myograph combined with pharmacological approaches were used to determine whether HHcy-mediated inflammatory signaling leads to endothelial dysfunction via stimulating ENaC. The data showed that 4 weeks after L-methionine diet the levels of plasma Hcy were significantly increased and the ENaC was dramatically activated in mouse aortic endothelial cells. Administration of benzamil, a specific ENaC blocker, ameliorated L-methionine diet-induced impairment of endothelium-dependent relaxation (EDR) and reversed Hcy-induced increase in ENaC activity. Pharmacological inhibition of NADPH oxidase, reactive oxygen species (ROS), cyclooxygenase-2 (COX-2)/thromboxane B2 (TXB2), or serum/glucocorticoid regulated kinase 1 (SGK1) effectively attenuated both the Hcy-induced activation of endothelial ENaC and impairment of EDR. Our data showed that both NADPH oxidase inhibitor and an ROS scavenger reversed Hcy-induced increase in COX-2 expression in human umbilical vein endothelial cells (HUVECs). Moreover, Hcy-induced increase in expression levels of SGK-1, phosphorylated-SGK-1, and phosphorylated neural precursor cell-expressed developmentally downregulated protein 4-2 (p-Nedd4-2) in HUVECs were significantly blunted by a COX-2 inhibitor. We show that Hcy activates endothelial ENaC and subsequently impairs EDR of mouse aorta, via ROS/COX-2-dependent activation of SGK-1/Nedd4-2 signaling. Our study provides a rational that blockade of the endothelial ENaC could be potential method to prevent and/or to treat Hcy-induced cardiovascular disease.