Equipment Supplement: Sodium Channel Control of Neuronal Excitability

项目摘要 电压门控钠通道（VGSC）对于动作电位的产生是必不可少的。此外， 直接靶向VGSC被广泛用于治疗常见疾病，如疼痛、情绪障碍、肌肉萎缩等。 痉挛癫痫和心律失常然而，由于分布广泛， 以及各种VGSC亚型对阻断剂的交叉敏感性。此外，这些药物不是 完全有效，强调了对靶向VGSC的新药的实质性需求。这促使我们 识别和表征VGSC功能可以调节的新机制。电压调节- 门控离子通道功能是调节神经元信号和脑功能的重要途径， 和G蛋白偶联受体（GPCR）形成内源性转导机制的主要元件 发生这种情况。然而，与其他离子通道不同，VGSC被认为是相对独立的。 对GPCR信号转导的调节不敏感。我们最近发现了一种由 已知与CaSR（钙敏感受体）相互作用的药物。这种途径是广泛的，存在于 绝大多数的新皮层神经元，并足以完全和可逆地阻断VGSC电流 最大限度地刺激。这种新的，动态的信号通路被定位为实质上调节 神经元兴奋性和大脑功能。对潜在机制的详细了解对于 了解它的许多影响。本提案的目的是确定CaSR调节剂如何调节 VGSC。使用电生理学和无偏见的生化方法相结合，我们将确定 受体介导VGSC电流的抑制，测量不同VGSC阻断的相对敏感性。 同种型，并确定该途径是否差异调节神经末梢和索马的动作电位。 这些特定的目的将检验CaSR调节剂通过VGSC的作用代表重要的新的 调节神经元兴奋性的途径。我们非常适合执行这个项目，因为我们的 初步数据和专业知识。我们的理论基础是，一部小说的识别和特征描述， 普遍的受体和下游途径将有助于我们理解一个普遍的和潜在的 强大的神经生物学信号通路。成功完成这些具体目标将是新的 药物靶点，并最终将导致新的治疗方法，以改善控制疼痛，癫痫发作，肌肉痉挛， 和心律失常。

PROJECT SUMMARY Voltage-gated sodium channels (VGSCs) are essential for action potential generation. Furthermore, drugs that directly target VGSCs are widely used to treat common diseases, such as pain, mood disorders, muscle spasms, seizures, and cardiac arrhythmias. However, side effects arise because of the widespread distribution of VGSCs and cross-sensitivity of the various VGSC subtypes to blockers. In addition, these drugs are not completely effective, underlining a substantial need for new drugs that target VGSCs. This has motivated us to identify and characterize new mechanisms by which VGSC function can be regulated. Regulation of voltage- gated ion channel function is an important pathway by which neuronal signaling and brain function is regulated, and G-protein coupled receptors (GPCRs) form a major element of the endogenous transduction mechanisms by which this occurs. However, unlike other ion channels, VGSCs have been assumed to be relatively insensitive to modulation by GPCR signaling. We have recently identified a pathway that is modulated by agents known to interact with the CaSR (calcium-sensing receptor). This pathway is widespread, present in the vast majority of neocortical neurons, and strong enough to completely and reversibly block VGSC currents when maximally stimulated. This novel, dynamic signaling pathway is positioned to substantially modulate neuronal excitability and brain function. Detailed knowledge about the underlying mechanisms is crucial to understand its many effects. The objectives of this proposal are to determine how CaSR modulators regulate VGSCs. Using a combination of electrophysiology and unbiased biochemical approaches we will identify the receptors mediating the inhibition of VGSC currents, measure the relative sensitivity to block of different VGSC isoforms, and determine if the pathway differentially regulates action potentials at nerve terminals and soma. These specific aims will test the hypothesis that CaSR modulators actions via VGSCs represent important new pathways for modulating neuronal excitability. We are ideally suited to perform this project because of our preliminary data and expertise. Our rationale is that the identification and characterization of a novel and prevalent receptor(s) and downstream pathway will facilitate our understanding of a prevalent and potentially powerful neurobiological signaling pathway. Successful completion of these specific aims will characterize new drug targets and eventually will lead to new therapeutics to improve control of pain, seizures, muscle spasm, and arrhythmias.