Tuning of CaV channel dynamics by stac proteins

黑质多巴胺能神经元的选择性变性 是帕金森病发展过程中的关键事件这些神经元是脆弱的， 进行自主起搏，不寻常地依赖于通过CaV1.3通道的Ca 2+内流。 与在PD发病过程中保持相对保护的其他起搏神经元不同，SNc 神经元具有更大的钙电流，钝化失活，从而加剧了 Ca 2+超载。鉴于其核心作用，识别调节Ca 2+通道的调节蛋白 SNc神经元的功能至关重要。一种有吸引力的调节候选物是富含半胱氨酸的SH 3 结构域（RNTs）蛋白，一种肌肉和神经元特异性蛋白，已成为一种必需的蛋白质。 骨骼肌兴奋-收缩机制的组成部分，并作为先天性 肌病即便如此，尽管stac 2- 突变与儿童期精神分裂症有关。根据初步数据 这表明SNc神经元中存在着NH3，其功能作用是选择性地减少 Ca 2 +/CaM依赖性失活（CDI）在异源系统中，我们在这里剖析了分子 功能，潜在的机制，以及在调整SNc起搏，利用 一系列分子工具和定量光学和电生理学方法。这 该项目将通过三个具体目标开创一个令人兴奋的发现时代。(1)β-内酰胺酶异构体 调整CaV功能？我们寻求制定一个统一的机制计划， CaV1.3，通过整合选择性剪接和RNA编辑的影响，并通过严格的 定量测定EAE对CDI、基线通道活性（PO）和表面膜的影响 贩卖人口（NATURAL）。(2)什么是分子决定因素和机制，支持和完善 CaV 1的调节？根据我们先前的机制研究，我们试图阐明 CaV1.3 PO和NH3的stac调节的分子基础，以及是否是生理或 病理生理过程可以微调神经调节。(3)多方面- 通过调节SNc起搏和Ca 2+信号调节CaV 1？在这里，我们阐明， stac 2的下调或上调调节内源性CaV 1，导致细胞凋亡的改变。 SNc神经元的起搏和动作电位形态。该项目承诺 在阐明CaV 1的多方面调节机制方面取得了前所未有的进展， Ca 2+通道生理学的新兴前沿。此外，这项工作可能会为以下方面提供新的见解： 调节过程，通过CaV1.3塑造Ca 2+流入SNc神经元，这是一个重要的脆弱性 PD发病机制和潜在的有前途的治疗靶点。

Selective degeneration of dopaminergic (DA) neurons of substantia nigra pars compacta (SNc) is a critical event in the progression of Parkinson’s disease. These neurons are vulnerable as they undergo autonomous pacemaking with an unusual reliance on Ca2+-influx via CaV1.3 channels. Unlike other pacemaking neurons that remain relatively protected during PD pathogenesis, SNc neurons have larger Ca2+-currents with blunted inactivation, thus aggravating the propensity for Ca2+-overload. Given its central role, identifying regulatory proteins that tune Ca2+-channel function in SNc neurons is critical. One attractive regulatory candidate is SH3 and cysteine rich domain (stac) protein, a muscle and neuron specific protein that has emerged as a requisite component of skeletal muscle excitation-contraction machinery and as a locus for congenital myopathies. Even so, the neuronal functions of stac remains poorly defined, although stac2- mutations have been linked to childhood-onset schizophrenia. Motivated by preliminary data showing both the presence of stac in SNc neurons, and its functional role to selectively diminish Ca2+/CaM-dependent inactivation (CDI) in heterologous systems, we here dissect the molecular functions of stac, underlying mechanisms, and potential role in tuning SNc pacemaking, utilizing a bevy of molecular tools and quantitative optical and electrophysiological approaches. This project will usher in an exciting era of discovery via three specific aims. (1) How do stac isoforms tune CaV function? We seek to develop a unified mechanistic scheme for stac regulation of CaV1.3, by incorporating effects of alternative-splicing and RNA-editing, and by rigorous quantification of stac effects on CDI, baseline channel activity (PO), and surface-membrane trafficking (Nmem). (2) What are molecular determinants and mechanisms that support and refine stac regulation of CaV1? Informed by our prior mechanistic study, we seek to elucidate the molecular underpinnings for stac-regulation of CaV1.3 PO and Nmem and whether physiological or pathophysiological processes may fine-tune stac modulation. (3) How does multiprong- modulation of CaV1 by stac tune SNc pacemaking and Ca2+ signaling? Here, we elucidate whether either downregulation or upregulation of stac2 tunes endogenous CaV1 leading to alterations in pacemaking and action potential morphology of SNc neurons. This project promises unprecedented progress in elucidating multifaceted mechanisms for stac regulation of CaV1, an emerging frontier for Ca2+-channel physiology. Furthermore, this work may shed new insights into regulatory process that sculpt Ca2+-influx via CaV1.3 into SNc neurons, an important vulnerability for PD pathogenesis and a potentially promising therapeutic target.