Sphingolipid Signaling in Endothelial Function

鞘氨醇-1-磷酸(S1P)是一种血清携带的生物活性脂质，调节着多种生物活性。 脉管系统。大多数S1P功能(如果不是全部的话)是由G蛋白偶联受体的S1P家族介导的 (GPCRs)。已鉴定出5种S1P受体亚型(S1P1-S1P5)。之前，我们展示了S1P1， GI偶联的GPCR，调节内皮细胞骨架结构、趋化作用、黏附分子的形成 连接(AJ)和紧密连接(TJ)，以及形态生成和血管生成反应。S1P/ S1P1信号增强血管屏障的跨内皮细胞电阻(TEER) 正直。此外，S1P1转导的信号抑制组胺诱导的血管渗漏。 SD大鼠。从机制上讲，S1P刺激导致形成两个不同的带状带 阻断剂-1(ZO-1)复合体调节内皮细胞TJ的形成和趋化反应 细胞(ECs)。这些结果表明，通过S1P1受体的S1P信号在调节 血管功能。重要的是，我们最近观察到S1P1受体存在于细胞核中 ECS的隔间。此外，我们还证明了Importin？1与第三个 S1P1受体的胞内环(I3)和S1P1受体的核转位是由 进口1-RAN核运输机械。抑制S1P1的核转位对BALB/C细胞无影响 最初S1P介导的TEER上升，但显著减弱了其持续上升。此外，内皮细胞 核S1P-S1P1信号轴刺激Cyr61和CTGF转录，这两种生长因子 在血管生成中具有重要的功能。总而言之，这些结果表明了这一点的中心假设 建议：质膜(PM-)和核(N)-S1P1受体在 调节内皮功能，特别是在血管完整性和血管生成方面“。 这项建议的特点是表征各自的信号级联和生物反应，由 PM-和N-S1P1受体特别关注血管完整性功能的调节和 血管生成反应。在这项建议中计划了三个具体目标，它们是：(1)描述 S1P1受体介导的内皮屏障完整性功能的机制，(2)决定血管内皮细胞 利用动物模型阐明血管内皮细胞中S1P1受体的生理功能。 体内的S1P1受体。这项拟议研究的成功不仅将导致小说的发现 调节GPCR信号的机制，但也可能发展为未来的治疗用途。

Sphingosine-1-phosphate (S1P), a serum-borne bioactive lipid, regulates various biological activities of vasculature. Most, if not all, S1P functions are mediated by the S1P family of G-protein-coupled receptors (GPCRs). Five S1P receptor subtypes (S1P1-S1P5) have been identified. Previously, we showed that S1P1, a Gi-coupled GPCR, regulates endothelial cytoskeletal architectures, chemotaxis, formation of adherens junctions (AJs) and tight junctions (TJs), as well as morphogenic and angiogenic responses. The S1P/ S1P1 signaling enhances the transendothelial electrical resistance (TEER), an indicator of vascular barrier integrity. Moreover, the S1P1-transduced signaling inhibits the histamine-induced vessel leakage in the Sprague Dawley (SD) rat. Mechanistically, S1P stimulation results in the formation of two distinct Zonula Occludens-1 (ZO-1) complexes which regulate the TJ formation and chemotactic response in endothelial cells (ECs). These results suggest that S1P signaling via the S1P1 receptor is important in the regulation of vascular functions. Importantly, we recently observed that S1P1 receptor is present in the nuclear compartment of ECs. Furthermore, we demonstrate that importin ¿1 directly interacts with the third intracellular loop (i3) of S1P1 receptor and the nuclear translocation of S1P1 receptor is mediated by the importin ¿1-Ran nuclear transport machinery. Inhibition of nuclear translocation of S1P1 has no effect on the initial S1P-mediated TEER rise, yet markedly diminishes its sustained rise. Furthermore, endothelial nuclear S1P-S1P1 signaling axis stimulates the transcription of Cyr61 and CTGF, two growth factors which are functionally important in angiogenesis. Together, these results suggest the central hypothesis of this proposal: "both the plasma membrane (PM-) and nuclear (N)-S1P1 receptors play critical roles in regulating endothelial functions, particularly in vascular integrity and angiogenesis". The main goal of this proposal is to characterize the respective signaling cascades and biological responses mediated by the PM- and N-S1P1 receptors with particular focus on the regulation of vessel integrity function and angiogenic response. Three specific aims are planned in this proposal, and they are: (1) characterize the mechanisms of S1P1 receptor-mediated endothelial barrier integrity function, (2) determine the functions of nuclear S1P1 receptor in ECs, and (3) utilizing animal models to elucidate the physiological functions of S1P1 receptor in vivo. The success of this proposed research will not only lead to the discovery of novel mechanisms mediating GPCR signaling, but may also develop into future therapeutic usages.