上皮细胞钠通道在血管稳态和重构中的作用及其分子调控机制

Dysfunction and/or injury of endothelium lead to imbalance of vascular homeostasis and to vascular remodeling, which also promote the incidence of cardiovascular diseases. The data shown by us and others indicate that epithelial sodium channel (ENaC) is expressed in vascular endothelial cells and that ENaC plays an important role in regulation of endothelium function. Our preliminary results suggest that the activity and expression levels of ENaC in rat mesenteric artery endothelial cells can be strongly stimulated by high salt diet. Alteration of ENaC activity and its expression contribute to reduced eNOS activity and NO production, as well as to the altered endothelial-dependent vascular relaxation. Our data also show that ENaC in mouse endothelial cells of thoracic aorta is stimulated by ox-LDL, an oxidized isoform of LDL. Based upon our previously published results and the preliminary data shown in this application, we hypothesize that both high salt and lipid metabolic disorder stimulate expression and activity of ENaC via oxidative stress and intracellular signaling and molecules, and subsequently causes dysfunction of endothelium, imbalance of vascular homeostasis and vascular remodeling; NO/H2S and Lovastatin may prevent high salt or lipid-metabolic disorder-induced endothelial dysfunction through inhibition of ENaC. We will use Dah1/Rapp salt-sensitive (SS) and Sprague-Dawley rats (SD), C57BL/6J and LDLr-/- mice, the primary cultured endothelial cells isolated from the animal models as described above, as well as HUVEC cell line combined with electrophysiological recordings in split-open arteries, molecular biology, imaging analysis, and wire myograph analysis to address our hypothesis. We will demonstrate the role of ENaC in maintaining the vascular homeostasis; we will determine whether high salt and disorder of lipid metabolism regulate ENaC and the mechanisms by which high salt and disorder of lipid metabolism-induced ENaC upregulation contribute to dysfunction of endothelium and the development of vascular dysfunction and remodeling; we will test whether NO/H2S donor and Lovastatin exert a protective effects on pathophysiological processes through inhibition of ENaC. The results obtained by proposed studies will gain our knowledge in understanding the molecular basis and mechanisms of vascular dysfunction and remodeling. Our results may provide rational for preventing and curing the cardiovascular diseases.

内皮功能障碍和损伤是血管性疾病的早期事件和始动因素。研究显示：内皮中的上皮细胞钠通道（ENaC）对调节血管功能具有重要作用。我们发现：高盐摄入/脂代谢紊乱导致的内皮ENaC表达/活性升高与内皮和血管功能障碍密切相关；然而，其分子机制及调控网络不明。基于已发表和本课题的前期研究结果，我们假设：高盐摄入/脂代谢紊乱通过显著上调内皮ENaC表达和持续激活ENaC，导致内皮中[Na+]显著升高，而使eNOS活性及NO合成降低，最终导致血管功能紊乱和血管重构。我们将应用野生型及疾病模式动物，结合多种研究方法，阐明ENaC在血管稳态中的作用，揭示高盐摄入/脂代谢紊乱导致内皮ENaC表达/活性升高、从而导致血管稳态失衡及血管重构的关键信号分子及节点；揭示小分子气体NO、H2S和他汀类药物如何通过抑制ENaC而显著减轻/延缓血管稳态失衡及结构重构，为血管功能紊乱和血管重构的早期干预提供新的靶点和干预手段。

本课题首次、系统地揭示了内皮ENaC在维持血管稳态及其在盐、糖脂代谢紊乱等病理因素刺激所致的血管稳态失衡的作用和详细的调控网络及关键分子。. 1）首次描述内皮ENaC的生物物理学特征，揭示ENaC在高脂导致的血管内皮紊乱，舒张功能障碍和动脉粥样硬化病理生理过程中的重要作用；发现高脂通过激活COX-2和Ox-LDL/LOX-1/sGC/PKG通路及NADPH介导的内皮ROS聚集而激活ENaC活性；ENaC特异阻断剂苯扎明可显著抑制高脂诱导的内皮依赖性舒张功能障碍和动脉粥样硬化，并揭示其机制；2）发现高盐或寒冷刺激致使盐敏感大鼠或SD大鼠的血浆中醛固酮水平显著升高，并通过其受体及其下游信号通路促进内皮ENaC表达及活性的机制；3）发现高盐导致的血清和血管BMP4水平升高通过p38 MAPK/Sgk1/Nedd4-2信号通路使内皮ENaC异常激活进而引起内皮依赖舒张功能障碍并导致高血压；4）发现棕榈酸通过引起细胞内Ca2+释放，通过激活NADPH/ROS/PI3K途径激活ENaC，小分子气体H2S通过氧化还原反应抑制棕榈酸引起的ENaC活性升高；5）揭示升高的同型半胱氨酸通过ROS/COX-2/Sgk1通路促进ENaC活性，进而导致血管内皮舒张功能障碍；6）揭示环孢霉素（CsA）及细胞内胆固醇聚集通过脂质依赖的氧化应激，调节ENaC表达同时激活ENaC诱发高血压的机制，阐明洛伐他汀通过抑制胆固醇合成而显著逆转上述进程的机制；7）揭示VEGF通路抑制剂（VEGFi）抗肿瘤靶向药导致内皮/血管功能紊乱和高血压的机制，发现补充精氨酸可缓解VEGFi所导致的高血压。.本课题的创新：1）首次在功能学层面揭示ENaC在血管稳态失衡和重构中的作用及分子调控网络；2）对于一些高血压人群，如盐敏感高血压和高血压伴高脂血症患者应用阿米洛里和他汀类治疗提供依据；3）为筛选高效特异ENaC阻断剂治疗高血压，预防动脉硬化提供理论基础。.项目组已经发表SCI收录，包括Hepatology , Hypertension,, Br J Pharmacol等文章13篇，其中IF > 10分文章1篇，10分 > IF > 5分7篇。获得黑龙江省政府自然科学一等奖。博士后出站5人，博士毕业7人，硕士毕业5人。申请国家发明专利一项。