SPECIFICITY IN ENDOTHELIAL CELL CALCIUM SIGNALING

内皮细胞钙信号转导的特异性。内皮细胞接受和整合与血流控制(即切应力和血管活性介质)、炎症和生长/修复相关的各种刺激。内皮细胞对这些刺激的不适当或缺陷反应可导致多种血管病变。所有这些刺激信号的传递部分依赖于细胞内钙的动员。在大血管内皮细胞中，细胞内的钙池由两个SERCA(血管内皮细胞)血浆钙ATPase(SERCA)来管理，SERCA3和SERCA2b泵是唯一表达的。缺乏SERCA3(SERCA3基因敲除)的小鼠出生时具有完整的血管系统。然而，这些小鼠的动脉对血管扩张剂乙酰胆碱没有反应。此外，缺乏SERCA3的主动脉内皮细胞不会对乙酰胆碱产生钙瞬变反应。在SERCA3基因敲除小鼠中，即使存在SERCA2b，内皮细胞活性的缺陷也会发生。这些观察结果导致了一种假设，即内皮细胞利用这两个SERCA泵所定义的不同的细胞内钙池来调节对不同类型刺激的反应。这个项目的目标是通过完成四个特定的目标来检验这一假设，证明SERCA3维持的钙池参与内皮细胞反应的一个子集，并且这个钙池与内皮细胞内SERCA2b管理的钙池是分开的。特定的AIMS 1和2将表征SERCA3和SERCA2b管理的钙在这些小鼠内皮细胞产生钙瞬变和四种血管刺激(剪切力、血管活性、炎症和血管修复)诱导的内皮细胞反应中的分布和空间组织，将为这些研究提供实验基础。在两只小鼠的细胞和血管之间观察到的选择性差异可以归因于SERCA3建立的钙库的缺失，并表明这些过程依赖于这个钙库。这些目标的完成将进一步深入了解钙介导的内皮细胞信号转导的特异性，从而为针对血管疾病的特定治疗提供可能的途径。

Specificity in Endothelial Cell Calcium Signaling. The endothelial receives and integrates a variety of stimuli related to blood flow control (i.e. shear stress and vasoactive mediators), inflammation, and growth/repair. Inappropriate or defective endothelial cell responses to these stimuli can lead to a variety of vascular pathologies. Transduction of signals from all of these stimuli relies, in part, on mobilization of intracellular calcium. In large vessel endothelial cells, intracellular calcium pools are managed by two sarco (endothelial cell) plasmic calcium ATPases (SERCA); the uniquely expressed SERCA3 and the ubiquitous SERCA2b pumps. Mice lacking SERCA3 (SERCA3 knockout) are born viable with intact vasculature. However, aortas from these mice fail to respond to the vasodilator acetylcholine. Furthermore, SERCA3-deficient aortic endothelial cells do not generate a calcium transient in response to acetylcholine. The defects in endothelial cell activity present in the SERCA3 knockout mouse occur even though SERCA2b is present. These observations have lead to the hypothesis that endothelial cells utilize distinct intracellular calcium pools, as defined by these two SERCA pumps, to mediate responses to different types of stimuli. The goal of this project is to test this hypothesis, through completion of four specific aims, by demonstrating that the calcium pool maintained by SERCA3 participates in a subset of endothelial cell responses and that this calcium pool is segregated from the SERCA2b-managed pool within the endothelial cell. Specific aims 1 and 2 will characterize the distribution and the spatial organization of the SERCA3- and SERCA2b- managed calcium in the generation of calcium transients and endothelial cell responses induced by four classes of vascular stimuli (shear stress, vasoactivity, inflammation, and vascular repair) in endothelial cells from these mice will provide the experimental basis for these studies. Selective differences observed between cells and vessels of the two mice can be attributed to the absence of calcium stores established by SERCA3 and indicate those processes relying on this calcium pool. Completion of these aims will provide further insight into how specificity in calcium-mediated endothelial cell signal transduction is established and thus provide possible avenues for specific therapies directed at treating vascular disease.