Roles of K channels in spiral ganglia neurons in health, diseases and aging.

描述（由申请人提供）：迄今为止，对影响我们老龄化人群的进行性听力损失（PHL）的潜在细胞和分子机制知之甚少。毛细胞和螺旋神经节神经元（SGN）的变性是PHL的常见表型。K+通道在内耳中的重要性得到了以下证据的支持：通道的特定突变导致人类毛细胞（HC）和SGN的变性。在这里，我们假设SGN中的K+通道调节静息膜电位及其兴奋性，以调节细胞内Ca 2+（Ca 2 +i）的通量，其作为关键的第二信使，决定SGN的发育、功能和存活。然而，过度的[Ca 2 +i]可诱导神经元死亡。我们进一步预测，在衰老过程中，在与SGN进行性变性相关的几种K+通道病中，K+通道的表达发生了深刻的变化，导致膜去极化，Ca 2+内流过度增加，从而引发Ca 2+诱导的凋亡性神经元死亡。该提案将确定K+通道的同源和异源多聚体如何赋予K+电流的多样性，以及孔形成α亚基的突变如何产生K+电流的深刻改变。我们还将了解细胞内和单程辅助亚基如何控制SGN中的K+通道。五个具体目标考虑; SGN中K+通道的基本特征赋予其作为K+转运蛋白的作用（目的1）;哪些K+通道亚基构成天然SGN K+电流（目的2）;可溶性胞质蛋白，K+通道相互作用蛋白（KChIP）如何调节K+通道电流的表面表达和性质（目的3）; K+通道的单通道亚基KCNE如何在健康和疾病中决定特定的K+通道功能（目的4）;以及在衰老过程中发生的介导PHL的生物化学和功能变化（目的5）。该提案使用正常和基因改变的小鼠作为实验模型，并利用经典技术（电生理学，生物化学和电子显微镜）和新的策略，使强大的分子生物学的最新进展（例如，siRNA敲除和病毒介导的基因转移）。对听觉科学特别重要的是，随着我们对通道的门控、渗透和药理学的理解变得更加精细，可能实现K+通道亚型特异性药物的合理设计。

DESCRIPTION (provided by applicant): To date, little is known about the underlying cellular and molecular mechanisms of progressive hearing loss (PHL) that affects our aging population. Degeneration of hair cells and spiral ganglia neurons (SGNs) are common phenotypes associated with PHL. The importance of K+ channels in the inner ear is underpinned by evidence that specific mutations of the channel result in degeneration of hair cells (HCs) and SGNs in humans. Here, we hypothesize that K+ channels in SGNs regulate the resting membrane potential and their excitability in order to modulate fluxes of intracellular Ca2+ (Ca2+i), which serves as a key second messenger, determining the development, function, and survival of SGNs. However, undue [Ca2+i] may induce neuronal death. We further predict that during aging and in several K+ channelopathies associated with progressive degeneration of SGNs, the expression of K+ channels are profoundly altered leading to membrane depolarization, excessive increased in Ca2+ influx, which triggers Ca2+- induced apoptotic neuronal death. The proposal will identify how homo- and hetero- multimers of K+ channels confer diversity of K+ currents, and how mutations of the pore- forming a-subunit may produce profound alterations of K+ currents. We will also learn how intracellular and single-pass accessory subunits control K+ channels in SGNs. Five specific aims consider; what elementary features of K+ channels in SGNs confer their roles as K+ transporters (Aim 1); what K+ channel subunits constitute native SGN K+ currents (Aim 2); how soluble cytoplasmic proteins, K+ channel interacting proteins (KChIP), regulate the surface expression and properties of K+ channel currents (Aim 3); how single-pass subunits of K+ channels, KCNEs, dictate specific K+ channel functions in health and disease (Aim 4); and the ensuing biochemical and functional changes that occur during aging (Aim 5) that mediates PHL. The proposal uses normal and genetically altered mice as the experimental models, and exploit classical techniques (electrophysiology, biochemistry and electron microscopy) and novel strategies made powerful by recent advances in molecular biology (e.g, siRNA knockdown and viral- mediated gene transfer). Of particular importance to auditory science is the possibility that a rational design of K+ channel subtype-specific drugs may be realized, as our understanding of the gating, permeation, and pharmacology of the channels becomes more refined.