Modulation of Cav 1.3 L-type Ca2+ channels by PDZ-protein interactions

描述（由申请人提供）：电压门控L型Ca 2+通道介导心脏、内分泌和神经功能所必需的Ca 2+信号。虽然Cav1.2是大多数组织中的主要类型的L型通道，但Cav1.3 L型通道在心律和神经元兴奋性中起主要作用。由于Ca 2+内流的微小变化可以深刻地影响细胞的兴奋性，调节Cav1.3通道的因子可以控制神经和心血管系统的正常和患病状态之间的平衡。在筛选特异性调节Cav1.3的信号分子时，我们发现了一种通过与含有PDZ结构域的蛋白质相互作用来调节这些通道的新方法。PDZ蛋白erbin与Cav1.3的11-亚基（111.3）的C-末端结构域（CT）结合，并在称为电压依赖性易化（VDF）的过程中显著增强对去极化刺激的通道开放。一个密切相关的蛋白质，densin-180，也与111.3 CT相互作用，但不影响VDF。相反，densin-180抑制Ca 2+依赖性Cav1.3失活，这种作用依赖于钙调蛋白依赖性激酶II的功能募集。基于这些发现，我们假设Cav1.3通道从根本上受到PDZ-蛋白相互作用的调节，这可能使这些通道在不同细胞类型中的信号传导潜力多样化。本提案的目标是表征Cav1.3通道通过这种PDZ相互作用进行差异调节的分子机制，以及使用分子生物学，免疫化学和电生理学的这种调节的生理意义。拟议的研究将阐明Cav1.3与其他L型通道的结构/功能关系和调节机制，这将拓宽我们对Cav1.3在调节心率，胰岛素分泌和神经适应精神兴奋剂方面的多种生理作用的理解。这项研究的长期目标是获得Cav1.3选择性药物开发的分子见解，这可能为心律失常，糖尿病和药物滥用提供新的有效治疗方法。公共卫生相关性：拟议的研究将调节电压门控Ca 2+通道。我们将阐明新的结构/功能关系和调节机制，这可能会改变心血管和神经系统的疾病状态。

DESCRIPTION (provided by applicant): Voltage-gated L-type Ca2+ channels mediate Ca2+ signals that are essential for cardiac, endocrine, and neural functions. Although Cav1.2 is the predominant class of L-type channel in most tissues, Cav1.3 L-type channels play a major role in cardiac rhythmicity and neuronal excitability. Since small changes in Ca2+ influx can profoundly influence cellular excitability, factors that regulate Cav1.3 channels may control the balance between normal and diseased states of the nervous and cardiovascular systems. In screening for signaling molecules that specifically modulate Cav1.3, we discovered a novel regulation of these channels by interactions with proteins containing motifs known as PDZ-domains. The PDZ-protein, erbin, binds to the C-terminal domain (CT) of the 11-subunit (111.3) of Cav1.3 and dramatically enhances channel opening in response to depolarizing stimuli in a process termed voltage-dependent facilitation (VDF). A closely related protein, densin-180, also interacts with the 111.3 CT but does not influence VDF. Instead, densin-180 inhibits Ca2+-dependent inactivation of Cav1.3 and this effect depends on functional recruitment of calmodulin-dependent kinase II. Based on these findings, we hypothesize that Cav1.3 channels are fundamentally regulated by PDZ-protein interactions, which may diversify the signaling potential of these channels in different cell-types. The goal of this proposal is to characterize the molecular mechanism by which Cav1.3 channels are differentially modulated by such PDZ interactions, and the physiological significance of this regulation using molecular biology, immunochemistry, and electrophysiology. The proposed studies will clarify structure/function relationships and modulatory mechanisms that distinguish Cav1.3 from other L-type channels, which will broaden our understanding of the diverse physiological roles of Cav1.3 in regulating heart-rate, insulin secretion, and neural adaptations to psychostimulants. The long-term objective of this research is to gain molecular insights into the development of Cav1.3-selective drugs, which may provide novel and effective treatments for cardiac arrhythmias, diabetes, and drug abuse. PUBLIC HEALTH RELEVANCE: The proposed research will modulate voltage-gated Ca2+ channels. We will elucidate new structure/function relationships and modulatory mechanisms, which may be altered in diseased states of the cardiovascular and nervous systems.