The role of NaV2.4 in mediation of resurgent sodium current

描述（由申请人提供）：回流电流是电压门控钠（Na）电流的一个不寻常的组成部分，它在复极化时流动。这种电流可能在放电模式、内在兴奋性和钠电流的调节中起重要作用，并且在许多脑区都有记录。这些大脑区域与共济失调、帕金森氏病、亨廷顿氏病、自闭症和其他运动障碍有着明确的联系。研究这种电流与这些疾病状态相关，因为任何完整的病理生理学模型都需要考虑到这种电流。先前的研究表明，恢复电流是由于蛋白质开放通道阻断颗粒的作用，该颗粒是分离的，但与Na通道α亚基相关。然而，负责的蛋白质机制仍然是一个谜，它的识别将有助于详细研究其机制并促进其原位操作。有证据支持和反对β 4 Na通道亚基（NaV2.4）是内源性阻断颗粒的假设。在这里，我们打算首先通过使用RNAi方法在培养中敲除表达并记录复活电流来直接测试亚基的必要性。其次，我们将检查这种击倒对射击模式的影响。最后，基于先前的工作，我们提出了实验来测试阻断机制是否是钠通道孔内局部麻醉受体位置的竞争性内源性配体。这一数据将对新的治疗手法和充分理解当前局麻、抗心律失常和抗惊厥药物的作用具有重要意义。综上所述，这些数据将有助于描述在许多大脑区域中发现的钠电流的关键组成部分的分子机制。

DESCRIPTION (provided by applicant): Resurgent current is an unusual component of voltage gated sodium (Na) current that flows upon repolarization. This current may play an important role in the firing patterns, intrinsic excitability, and modulation of sodium currents and it has been recorded in many brain regions. These brain regions have well-established links to ataxias, Parkinson's Disease, Huntington's Disease, autism, and other movement disorders. Studying this current has relevance for these disease states in that any complete models of pathophysiology would need to take this current into account. Prior work has suggested that resurgent current is due to the actions a proteinaceous open-channel blocking particle that is separate but associated with the Na channel alpha subunit. However, the protein machinery responsible still remains a mystery and its identification would aid detailed study of the mechanism and facilitate its manipulation in situ. There is evidence for and against the hypothesis that the beta4 Na channel subunit (NaV2.4) is the endogenous blocking particle. Here we intend to first test the necessity of the subunit directly by knocking down the expression in culture using an RNAi approach and recording resurgent current. Secondly we will examine the effect of this knockdown on firing patterns. Lastly, based on prior work we propose experiments to test if the blocking machinery is a competitive endogenous ligand for the local anesthetic receptor site within the sodium channel pore. This data will be important to new therapeutic manipulations and fully understanding the effects of current local anesthetic, anti-arrhythmic, and anticonvulsant drugs. Together these data will help characterize a molecular mechanism for a critical component of sodium currents found in a number of brain regions.