Biobehavioral Health Science Division, College of Nursing, Division of Translational & Regenerative Medicine, College of Medicine, University of Arizona, Tucson, AZ, United States.
Biobehavioral Health Science Division, College of Nursing, Division of Translational & Regenerative Medicine, College of Medicine, University of Arizona, Tucson, AZ, United States.
Microvasc Res. 2018 Mar;116:26-33. doi: 10.1016/j.mvr.2017.10.001. Epub 2017 Oct 16.
The amiloride-sensitive epithelial sodium channel (ENaC) has been characterized in a variety of non-epithelial tissues. In the current study we sought to understand the effect of angiotensin II on δ ENaC function using human umbilical vein endothelial cells (HUVECs). The δ ENaC subunit is found in humans, but notably absent in rat and most mouse epithelial tissues. In this study we report the presence of δ ENaC in HUVECS with a half-life of ~80min and a change in δ ENaC abundance when HUVECs were treated with angiotensin II. We also observed that angiotensin II increased apical membrane expression of δ ENaC and decreased protein ubiquitination. Equivalent short circuit current measurements showed angiotensin II increased δ ENaC ion transport in HUVEC cells. Treatment with the antioxidant apocynin attenuated angiotensin II mediated effects indicating an important role for angiotensin-derived HO in δ ENaC subunit regulation. Whole cell recordings from oocytes injected with δβγ ENaC shows HO-sensitive current. These results suggest that δ ENaC subunits can make up functional channel in HUVEC cells that are regulated by angiotensin II in a redox-sensitive manner. The novel findings have significant implications for our understanding of the role of ENaC in vascular conditions in which oxidative stress occurs.
氨氯吡咪敏感的上皮钠离子通道（ENaC）已在多种非上皮组织中得到鉴定。在本研究中，我们试图了解血管紧张素 II 对 δ ENaC 功能的影响，使用的细胞系为人脐静脉内皮细胞（HUVEC）。δ ENaC 亚基在人体中被发现，但在大鼠和大多数小鼠上皮组织中明显不存在。在这项研究中，我们报告了 δ ENaC 在 HUVEC 中的存在，其半衰期约为 80 分钟，并且当 HUVEC 用血管紧张素 II 处理时，δ ENaC 的丰度会发生变化。我们还观察到血管紧张素 II 增加了 δ ENaC 在顶端膜上的表达，并减少了蛋白质的泛素化。等效的短路电流测量表明，血管紧张素 II 增加了 HUVEC 细胞中 δ ENaC 的离子转运。抗氧化剂 apocynin 的处理减弱了血管紧张素 II 介导的作用，表明血管紧张素衍生的 HO 在 δ ENaC 亚基调节中起重要作用。用 δβγ ENaC 注射的卵母细胞进行全细胞记录显示出 HO 敏感电流。这些结果表明，δ ENaC 亚基可以在 HUVEC 细胞中构成功能性通道，该通道受血管紧张素 II 以氧化还原敏感的方式调节。这些新发现对我们理解 ENaC 在发生氧化应激的血管状况中的作用具有重要意义。
