Department of Cardiovascular Medicine, Graduate School of Medicine, the University of Tokyo, Tokyo 113-8655, Japan.
Department of Cardiovascular Medicine, Graduate School of Medicine, the University of Tokyo, Tokyo 113-8655, Japan; Jichi Medical University, Shimotsuke 329-0498, Japan.
J Biol Chem. 2013 May 17;288(20):14497-14509. doi: 10.1074/jbc.M112.448522. Epub 2013 Apr 2.
Vascular endothelial function is impaired in hypercholesterolemia partly because of injury by modified LDL. In addition to modified LDL, free cholesterol (FC) is thought to play an important role in the development of endothelial dysfunction, although the precise mechanisms remain to be elucidated. The aim of this study was to clarify the mechanisms of endothelial dysfunction induced by an FC-rich environment. Loading cultured human aortic endothelial cells with FC induced the formation of vesicular structures composed of FC-rich membranes. Raft proteins such as phospho-caveolin-1 (Tyr-14) and small GTPase Rac were accumulated toward FC-rich membranes around vesicular structures. In the presence of these vesicles, angiotensin II-induced production of reactive oxygen species (ROS) was considerably enhanced. This ROS shifted endothelial NOS (eNOS) toward vesicle membranes and vesicles with a FC-rich domain trafficked toward perinuclear late endosomes/lysosomes, which resulted in the deterioration of eNOS Ser-1177 phosphorylation and NO production. Angiotensin II-induced ROS decreased the bioavailability of eNOS under the FC-enriched condition.
血管内皮功能在高胆固醇血症中受损，部分原因是修饰的 LDL 造成的损伤。除了修饰的 LDL，游离胆固醇（FC）被认为在血管内皮功能障碍的发展中起着重要作用，尽管确切的机制仍有待阐明。本研究的目的是阐明富含 FC 的环境诱导的血管内皮功能障碍的机制。用 FC 负载培养的人主动脉内皮细胞，诱导形成由富含 FC 的膜组成的泡状结构。筏蛋白，如磷酸化小窝蛋白-1（Tyr-14）和小 GTP 酶 Rac，在富含 FC 的膜周围向泡状结构聚集。在这些囊泡存在的情况下，血管紧张素 II 诱导的活性氧（ROS）的产生大大增强。这种 ROS 将内皮型一氧化氮合酶（eNOS）推向囊泡膜，富含 FC 的囊泡向核周晚期内体/溶酶体转移，导致 eNOS Ser-1177 磷酸化和 NO 产生恶化。在富含 FC 的条件下，血管紧张素 II 诱导的 ROS 降低了 eNOS 的生物利用度。
