CA INFLUX FACTOR-- STRUCTURE/FUNCTION & ROLE IN DIABETES

许多信号转导途径依赖于 激动剂诱导的细胞质游离Ca 2+增加。这一过程的初始阶段 反应通常是由于生成肌醇1，4，5-三磷酸和 随后从内质网（ER）释放Ca 2+。耗尽 ER Ca 2+库的增加导致细胞外Ca 2+流入细胞内， 在细胞质中，这一过程被称为容量性或储存操作的Ca 2+内流（SOCE）。 SOCE与一系列引人注目的生物过程有关，包括T 细胞活化、胰岛素分泌、血管收缩和心脏 发展一种解释病毒传播的假说 关于内质网Ca 2+耗尽质膜的信息提出了一个新的观点， 新型可扩散信使分子Ca 2+内流因子的关键作用 （ClF）.在过去的一年里，这组人收集的数据显示， 研究人员提供了强有力的支持的结论，CIF存在， 它是在内质网钙库耗尽时合成的，它负责 激活两个不同的储存操作的质膜钙通道。 影像学和膜片钳技术为CIF的功能研究提供了独特的， 独立核实的哺乳动物CIF数据。此外，该集团还 确定酿酒酵母是遗传缺陷的， 细胞器Ca 2 + ATP酶也产生CIF，迄今为止， 它的哺乳动物对应物。这种廉价而丰富的材料来源， 正在进行的CIF纯化方案，以及 已经开发了一个独特的位置，以净化这个群体， 在结构上表征这种新型信号分子。实验也将 以确定ER Ca 2+产生CIF的生物合成途径 存储耗尽，并定义CIF激活这两个 质膜Ca 2 + +通道，有助于SOCE。的信息 我们的成果将被应用于一个主要的健康问题，糖尿病， 被潜在的SOCE损伤所误导。高血糖诱导的 己糖胺生物合成途径和/或蛋白激酶C的激活将 作为SOCE的可能调节剂进行研究。所描述的方法将 涉及一个跨学科、多名调查员的倡议， 生物学、生物化学和结构学的方法来解决这个问题。成功 这些研究的完成将提供关于SOCE的关键信息， 定义糖尿病的新治疗靶点。

Numerous signal transduction pathways are dependent upon agonist-induced increases in cytoplasmic free Ca2+. The initial phase of this response is often due to the generation of inositol 1,4,5-trisphosphate and a subsequent release of Ca2+ from the endoplasmic reticulum (ER). The depletion of ER Ca2+ stores results in an influx of extracellular Ca2+ into the cytoplasm, a process termed capacitative or store-operated Ca2+ entry (SOCE). SOCE is implicated in a remarkable array of biological processes, including T cell activation, the secretion of insulin, vasoconstriction, and heart development. One hypothesis that has emerged to explain the transmission of information regarding ER Ca2+ depletion to the plasma membrane proposes a critical role for a novel diffusible messenger molecule, Ca2+ influx factor (ClF). In the last year data that have been gathered by this group of investigators provide strong support for the conclusion that CIF exists, that it is synthesized upon ER Ca2+ store depletion, and that it is responsible for activation of two distinct store-operated plasma membrane Ca2+ channels. Imaging and patch-clamp techniques for CIF's function have provided unique and independently verified data on mammalian CIF. In addition, this group has determined that Saccharomyces cerevisiae that are genetically deficient in an organellar Ca2+ ATPase also make a CIF that to date is indistinguishable from its mammalian counterpart. This inexpensive and plentiful source of material, the purification schemes for CIF that are well underway, and the assays that have been developed place this group in a unique position to purify and structurally characterize this novel signaling molecule. Experiments also will be performed to define the biosynthetic pathway for generating CIF upon ER Ca2+ store depletion, and to define the mechanism by which CIF activates the two plasma membrane Ca2+ + channels that contribute to SOCE. The information that we gain will be applied to a major health problem, diabetes, which mischaracterized by an underlying impairment of SOCE. The hyperglycemia-induced activation of the hexosamine biosynthetic pathway and/or protein kinase C will be investigated as possible regulators of SOCE. The described approach will involve a cross-disciplinary, multi-investigator initiative that applies biologic, biochemical, and structural procedures to this problem. Successful completion of these studies will provide pivotal information on SOCE and may define novel therapeutic targets for diabetes.