Chemical biological dissection of Ca2+ entry through Ca2+ channels

项目摘要 主要研究者：大卫，医学博士，哲学博士 一种类型的电压激活的Ca 2+渗透性离子通道，被称为CaV1.3，正在成为一种杰出的 Ca 2+进入位于脑节律和神经退行性疾病中心的神经元的途径。 打开CaV1.3所需的较低的跨膜电压允许这些通道对CaV1.3的形成起重要作用。 起搏和阈下电压波动。CaV1.3通道因此构成主要的Ca 2+进入 许多神经元经历振荡和阈下活动的模块。没有任何地方是钙离子进入功能 比黑质神经元更显著，其中CaV1.3通道提供了大部分的Ca 2+进入， 同时驱动对运动控制至关重要的快速起搏。值得注意的是，黑质变性 神经元是帕金森病（PD）的核心，细胞内Ca 2+失调和超载是至关重要的， PD发病机制。因此，一种非常有前途的新型PD治疗方法涉及新兴的 寻找选择性抑制CaV1.3通道开放的小分子。然而，相对来说， 已知控制CaV1.3通道开放概率PO的机制。正在进行的小分子 因此，筛选依赖于秩相关性，在很大程度上缺乏已知的药物结合的通道界面。 可能会改变开放。最近发现CaV1.3通道并不是 单体，但由许多RNA编辑和剪接变体组成，每种变体对细胞增殖具有潜在的不同影响。 通道的开放概率PO。变异相关的PO调节的潜在机制目前是 晦涩难懂。此外，GPCR介导的质膜脂质PIP 2的变化有力地调节PO，但它不影响PIP 2的表达。 不知道这是如何发生的，以及它如何与编辑/拼接变化相关。合在一起， 与这两个系统的联系排除了对Ca 2+如何通过这些通道进入的定量理解 有助于发病机制，并掩盖了合理的小分子筛选CaV1.3调节剂的途径。 然而，事实证明，仅凭传统手段难以取得进展。因此，本项目建议澄清 CaV1.3 PO调制融合电生理学与新的化学生物学和活细胞FRET工具。 总的来说，这一建议承诺优雅的澄清，简化和统一看似多样化的 CaV1.3 PO调节机制;识别可作为发现目标的通道接口 小分子PO调节剂;和新的化学生物学和FRET为基础的工具，广泛适用性。

PROJECT SUMMARY PI: David Yue, MD, PhD One type of voltage-activated Ca2+-permeable ion channel, known as CaV1.3, is emerging as a preeminent Ca2+ entry pathway into neurons residing at the epicenter of brain rhythmicity and neurodegenerative disease. The lower transmembrane voltages required to open CaV1.3 allow these channels to contribute importantly to pacemaking and subthreshold voltage fluctuations. CaV1.3 channels thus constitute a dominant Ca2+ entry module into many neurons undergoing oscillatory and subthreshold activity. Nowhere is this Ca2+ entry function more salient than in substantia nigral neurons, where CaV1.3 channels furnish the lion's share of Ca2+ entry, while driving rapid pacemaking essential for movement control. Notably, degeneration of substantia nigral neurons is central to Parkinson's disease (PD), and intracellular Ca2+ dysregulation and overload are crucial to PD pathogenesis. Accordingly, a highly promising avenue for novel PD therapeutics involves the burgeoning search for small molecules that selectively inhibit the opening of CaV1.3 channels. Yet, comparatively little is known about the mechanisms controlling the open probability PO of CaV1.3 channels. Ongoing small-molecule screens thereby rely on rank empiricism, largely bereft of known channel interfaces to which drug binding would likely alter opening. Multiplying the challenge is the recent discovery that CaV1.3 channels are not monolithic, but comprised of numerous RNA-edited and splice variants, each with potentially distinct effects on the open probability PO of channels. The mechanism underlying variant-related PO modulation is currently obscure. Additionally, GPCR-mediated changes in the plasmalemmal lipid PIP2 powerfully regulates PO, but it is unknown how this occurs, and how it relates to edited/splice variation. Together, the mechanistic void relating to these two systems precludes quantitative understanding of how Ca2+ entry through these channels contributes to pathogenesis, and obscures the path to rational small-molecule screens for CaV1.3 modulators. Yet, forward progress has proven difficult by traditional means alone. This project thus proposes to clarify CaV1.3 PO modulation by melding electrophysiology with novel chemical-biological and live-cell FRET tools. Overall, this proposal promises elegant clarification, simplification, and unification of seemingly diverse mechanisms of CaV1.3 PO modulation; identification of channel interfaces that could be targeted for discovery of small-molecule PO modulators; and new chemical-biological and FRET-based tools of wide applicability.