Specificity of calcium channels in neuronal signaling

描述（由申请人提供）：电压门控Ca2+通道（VGCCs）是跨膜蛋白，在激活时允许Ca2+进入。除了它们的致电作用，vgc在膜去极化和广泛的非电活动之间提供了关键的联系。Ca2+内流通过不同类型的vgcc可以激活/调节不同的细胞信号级联。vgc也是多种第二信使调制的靶标。磷酸化和去磷酸化是快速调控Ca2+通道活性的重要手段。越来越多的证据表明，大分子信号复合物的形成是Ca2+通道特异性作用的机制之一，也是蛋白激酶和/或磷酸酶对通道活性的快速调节。该项目的长期目标是了解Ca2+通道伙伴蛋白在神经元信号传导中的独特作用。在本应用中，我们将重点关注三种新的Ca2+通道伴侣蛋白，通过酵母双杂交筛选鉴定，它们在PKC信号复合物的形成以及将mrna靶向树突和/或轴突以进行活性依赖的局部蛋白合成中的作用。几个不同的假设将被测试，使用分子和细胞生物学，生物化学，荧光成像和电生理学相结合的方法。我们将讨论：(1)生理因素，如蛋白激酶的磷酸化，调节pkce - eh - n型Ca2+通道复合物的形成。(2)存在新的Ca2+结合域，负责PKCe-ENH和en - n型Ca2+通道相互作用的差异调节。(3)功能性PKC信号复合体包括一个蛋白磷酸酶PP2ca，它直接结合到Ca2+通道的c端。(4)一种新的通道伙伴蛋白PQ-46是一种RNA结合蛋白，可结合N-和P/ q型Ca2+通道，可能参与mrna靶向树突和/或轴突的活性依赖。这些结果将揭示通过蛋白质-蛋白质相互作用建立的细胞信号网络如何实现其特异性。这项研究的结果将提供大脑信号转导的分子机制，有助于理解正常的神经功能，如学习和记忆，并为神经系统疾病，如阿尔茨海默病提供原因。

DESCRIPTION (provided by applicant): Voltage-gated Ca2+ channels (VGCCs) are transmembrane proteins, which allow Ca2+ entry upon activation. In addition to their electrogenic role, VGCCs provide a pivotal link between membrane depolarization and a wide range of non-electrical activities. Ca2+ influx through different types of VGCCs can activate/regulate distinct cellular signaling cascades. VGCCs are also targets for modulation by a variety of second messengers. Phosphorylation and dephosphorylation are important means of rapid regulation of the Ca2+ channel activity. Emerging evidence shows that formation of macromolecular signaling complexes is one the of the mechanisms for the specificity of the Ca2+ channel action as well as rapid regulation of the channel activity by protein kinases and/or phosphatases. The long term goal of this project is to understand the unique role of Ca2+ channel partner proteins in neuronal signaling. In this application, we will focus on three novel Ca2+ channel partner proteins, identified via yeast two-hybrid screening, for their roles in formation of a PKC signaling complex as well as in targeting mRNAs to dendrites and/or axons for activity-dependent localized protein synthesis. Several different hypotheses will be tested, using the combined approaches of molecular and cell biology, biochemistry, fluorescent imaging and electrophysiology. We will address: (1) Physiological factors, such as phosphorylation by protein kinases, regulate formation of the PKCe-ENH-N-type Ca2+ channel complex. (2) Novel Ca2+ binding domains exist, responsible for differential regulation of the interactions between PKCe-ENH and ENH-N-type Ca2+ channels. (3) The functional PKC signaling complex includes a protein phosphatase, PP2ca, which binds directly to the C-terminus of Ca2+ channels. (4) A novel channel partner protein, PQ-46, which is an RNA binding protein and binds to N- and P/Q-type Ca2+ channels, may be involved in activity dependent targeting of mRNAs to dendrites and/or axons. The results will shed light on how the cellular signaling network, established via protein-protein interactions, achieves its specificity. Results of this study will provide molecular mechanisms of signal transduction in the brain and will help understand normal neurological functions, such as learning and memory, and provide reasons for neurological disorders, such as Alzheimer's disease.