The Role of Stanniocalcin 2 in Calcium Homeostasis and Neuronal Pathology

描述(由申请人提供)：钙稳态的调节和未折叠蛋白反应(UPR)是神经病理生理学中两个特别重要的过程。Stanniocalcin 2(STC2)是一种分泌型糖蛋白，被认为在钙稳态中发挥作用。作为UPR的一部分，STC2也在大脑中动脉闭塞后的大鼠脑中表达，下调STC2的表达使细胞对缺氧和内质网应激敏感。由于STC2同时参与UPR和钙调节，该蛋白可能在神经系统中发挥特别重要的作用。这项建议的目的是阐明STC2的功能，特别强调它在神经病理生理学中的可能作用。目的1：研究STC2表达对STIM1功能的影响我的初步数据表明，STC2表达缺失导致钙离子通过钙离子通道(SOCs)进入增加，并且STC2可以与内质网钙离子传感器STIM1相互作用。因此，我将验证STC2通过改变STIM1介导的SOCs调节来影响钙内流的假设。具体地说，我将进行活细胞成像实验，以测量在存在或不存在STC2表达的情况下，STIM1在存储耗尽后的易位。我还将通过测量STIM1和SOC之间的FRET来测试STC2表达对ST1M1和SOC之间相互作用的影响。目的：研究谷氨酸暴露后STC2对细胞内钙稳态的影响。STC2在损伤后的脑组织中表达，在培养的细胞中具有细胞保护作用。此外，STC2表达的缺失会导致钙内流显著增加。因此，我将检验这一假设，即在钙依赖性神经元损伤的背景下，STC2介导的钙稳态调节对于神经元存活是重要的。我将比较暴露于谷氨酸后STC2/和STC2-/-神经元[钙]i水平的变化。我还将使用储存操作的钙内流抑制剂来确定这一途径在STC2介导的谷氨酸诱导的神经元损伤效应中的重要性。 公共卫生相关性：神经性疾病对公共卫生造成重大负担。STC-2可能在神经系统的基本过程中发挥重要作用。因此，这些研究将增加我们对神经元损伤和神经退行性疾病的基本机制的理解。 注：下面以基本上未经编辑的形式提供了对个别审查员的批评。这些评论是在审查会议之前编写的，在会议讨论之后可能没有更新或修订。因此，它们可能不能完全反映个别审评员在小组讨论结束时的最后意见或小组的最终多数意见。以上讨论摘要概述了小组讨论的最终结果。

DESCRIPTION (provided by applicant): Regulation of calcium homeostasis and the unfolded protein response (UPR) are two processes of particular importance in neuronal pathophysiology. Stanniocalcin 2 (STC2) is a secreted glycoprotein thought to play a role in calcium homeostasis. Expressed as part of the UPR, STC2 is also induced in the rat brain after middle cerebral artery occlusion and knockdown of STC2 expression sensitizes cells to hypoxia and endoplasmic reticulum stress. Since STC2 is involved in both the UPR and calcium regulation, this protein may play a particularly important role in the nervous system. The objective of this proposal is to elucidate the function of STC2, with special emphasis on its possible role in neuronal pathophysiology. Aim 1: Investigate the effect of STC2 expression on STIM1 function My preliminary data demonstrates that loss of STC2 expression leads to an increase in calcium entry through store-operated calcium channels (SOCs) and that STC2 can interact with the ER calcium sensor STIM1. Therefore, I will test the hypothesis that STC2 affects calcium entry by altering STIM1 mediated regulation of SOCs. Specifically, I will conduct live cell imaging experiments to measure translocation of STIM1 after store depletion in the presence or absence of STC2 expression. I will also test the effect of STC2 expression on the interaction between ST1M1 and SOCs by measuring FRET between STIM1 and SOCs before and after calcium store depletion. Aim 2: Characterize STC2 mediated effects on calcium homeostasis following glutamate exposure STC2 is expressed in the brain following injury and plays a cytoprotective role in cultured cells. In addition, loss of STC2 expression leads to a significant increase in calcium influx. Therefore, I will test the hypothesis that STC2 mediated regulation of calcium homeostasis is important for neuronal survival in the context of calcium dependent neuronal injury. I will compare changes in [Ca2+]i levels between STC2+/+ and STC2-/- neurons following exposure to glutamate. I will also use inhibitors of store-operated calcium entry to determine the importance of this pathway in STC2 mediated effects on glutamate-induced neuronal injury. Public Health Relevance: Neurological disorders pose a significant public health burden. STC 2 may play an important role in fundamental processes of the nervous system. Therefore, these studies will increase our understanding of the basic mechanisms underlying neuronal injury and neurodegenerative disease. NOTE: The critiques of individual reviewers are provided below in an essentially unedited form. These critiques were prepared prior to the review meeting and may not have been updated or revised subsequent to the discussion at the meeting. Therefore, they may not fully reflect the final opinions of the individual reviewers at the close of group discussion or the final majority opinion of the group. The Resume and Summary of Discussion above summarizes the final outcome of the group discussion.