Ion Channel Function in Auditory & Vestibular hair cells

本文的研究重点是KCNQ钾通道在听觉和前庭系统感觉毛细胞中的功能。 这类新发现的电压门控离子通道的五个成员中有四个的突变会导致遗传性人类疾病。 这些蛋白质中至少有三种在听觉和前庭周围表达：KCNQ1，3和4。 其中两个突变，KCNQ1和4，导致严重的听觉功能障碍。虽然这些遗传性疾病的病因还不清楚，但深刻的感觉缺陷意味着KNCQ蛋白在正常听觉功能中的重要作用。该项目有两个主要目标。 第一个目标是将KCNQ钾通道的表达与听觉和前庭毛细胞的正常生理学相关联。这将为KCNQ基因家族中的突变如何导致病理状态提供新的见解。 第二个目标是研究KCNQ通道在前庭外周突触传递中的作用。 具体来说，我们将测试的假设，即I型毛细胞传入突触利用一种新形式的K+依赖性神经传递。为了解决这些问题，我们制定了一项共同战略。 这些钾通道的成孔区域内的突变以主导方式起作用以阻断传导。 使用病毒介导的基因转移，我们将表达突变KCNQ基因在细胞的器官型培养从小鼠的听觉和前庭器官。 突变KCNQ基因在正常细胞中的表达将抑制野生型KCNQ亚基的活性。 为了分析功能破坏，我们将表征感染细胞的电生理特性，通过共表达绿色荧光蛋白来鉴定，以及邻近的未感染对照细胞。 因此，在一个特定的和控制的方式，我们将链接与其生理相关的分子身份。

The studies proposed here focus on the function of KCNQ potassium channels in the sensory hair cells of the auditory and vestibular systems. Mutations in four of the five members of this newly discovered class of voltage-gated ion channels cause inherited human diseases. At least three of these proteins are expressed in the auditory and vestibular periphery: KCNQ1, 3 and 4. Mutations in two of them, KCNQ1 and 4, cause severe auditory dysfunction. Although the etiologies of these inherited conditions are not well understood, the profound sensory deficits imply an important role for KNCQ proteins in normal auditory function. This project has two main goals. This first goal is to correlate expression of KCNQ potassium channels with the normal physiology of auditory and vestibular hair cells. This will provide new insight into how mutations in the KCNQ gene family lead to pathological states. The second goal is to investigate the role of KCNQ channels in synaptic transmission in the vestibular periphery. Specifically, we will test the hypothesis that the type I hair cell afferent synapse utilizes a novel form of K+-dependent neurotransmission. To address these questions we have devised a common strategy. A mutation within the pore-forming region of these potassium channels acts in a dominant manner to block conduction. Using virus-mediated gene transfer we will express mutant KCNQ genes in cells of organotypic cultures from the mouse auditory and vestibular organs. Expression of mutant KCNQ genes in normal cells will suppress the activity of wildtype KCNQ subunits. To assay for disrupted function we will characterize the electrophysiological properties of infected cells, identified by coexpression of green fluorescent protein, and neighboring uninfected control cells. Thus, in a specific and controlled manner we will link a molecular identity with its physiologic correlate.