Analysis of dynamics of splenic sinus endothelial cells for controlling of blood cell passage

以往的研究表明，脾静脉窦内皮细胞是控制血细胞通过脾索的关键部位。对于内皮细胞的功能，胞浆游离钙([Ca^&lt；2+&gt；]i)对体液因素或血流动力的调节是细胞内转导的重要步骤。细胞内钙离子是介导多种重要血管内皮细胞功能的第二信使，包括血管活性物质的产生、细胞增殖、基因表达、细胞骨架重塑、细胞收缩和VE-钙粘附素的分解，从而增加内皮通透性。[Ca^&lt；2+&gt；]i的动员是由受体介导的钙通道、内质网钙离子释放、与瞬时受体电位(Trp)通道密切相关的钙离子通道(SOCs)以及机械敏感性引起的钙离子内流等途径介导的。肌苷三磷酸受体(I…更多的P_3R和RyR是调节细胞内钙离子释放的主要途径，IP_3R和RyR与Trp通道的偶联已有报道。除了肌苷-1，4，5-三磷酸介导的钙动员和从兰诺定敏感池释放钙外，通过色氨酸通道的钙内流也被认为是内皮细胞钙离子释放的重要组成部分。本研究用激光共聚焦扫描显微镜和透射电子显微镜观察了TRPC1及其相关通道和蛋白IP_3R、RyR、VE-cadherin和CRT在大鼠脾静脉窦内皮细胞中的存在和超微结构定位，以阐明TRPC1在窦内皮细胞信号转导中的作用。此外，我们还观察了VE-钙粘蛋白、β-连环素和p120-连环素在大鼠脾静脉窦内皮细胞中的定位，以表征由钙粘附素-连环素复合体介导的粘连连接形成的存在和分布。免疫标记在大鼠脾静脉窦内皮细胞的不同水平上均可见，并在窦内皮细胞中间歇性地观察到。较少

Endothelial cells of the splenic sinus have been previously investigated as a critical site for controlling blood cell passage through the splenic cord. For endothelial functionality, modulation of free cytosolic calcium ([Ca^<2+>]i) in response to humoral factors or hemodynamic forces is an essential step of intracellular transduction. Intracellular Ca^<2+> is a second messenger mediating a variety of important vascular endothelial cell functions, including the production of vasoactive substances, cell proliferation, gene expression, cytoskeleton remodelling, cell contraction, and disassembly of VE-cadherin with consequent increase in endothelial permeability. Mobilization of [Ca^<2+>]i is mediated by receptor-mediated Ca^<2+> channels, Ca^<2+> release from endoplasmic reticulum, store-operated calcium channels (SOCs) closely correlated with transient receptor potential (TRP) channels, and Ca^<2+> entry through mechanosensitivity, among others. Inosito-1,4,5-trisphosphate receptors (I … More P_3R) and RyR are the main conduit for the regulated release of Ca^<2+> from intracellular stores, and coupling of IP_3R and RyR to TRP channels has been reported. In addition to inosito-1,4,5-trisphosphate mediated Ca^<2+> mobilization and Ca^<2+> release from ryanodine-sensitive pools, Ca^<2+>-influx through TRP channels has also been suggested to be an important component in endothelial Ca^<2+>-signaling.In the present study, the presence and ultrastructural localization of TRPC1 and the closely associated channels and proteins, IP_3R,RyR,VE-cadherin, and CRT, in the sinus endothelial cells of rat spleen were examined by confocal laser scanning microscopy and transmission electron microscopy to elucidate the role of TRPC1 in signal transduction in sinus endothelial cells. Moreover, the localization of VE-cadherin, β-catenin, and p120-catenin in the rat spleen sinus endothelial cells was examined to characterize the presence and distribution of adherens junction formation mediated by the cadherin-catenin complex and immunolabeling was evident at various levels in the lateral junctional membranes and was intermittently observed in the sinus endothelium. Less