Functional development of hair cells

描述（由申请人提供）：内耳毛细胞具有将头部运动和声音转换成电信号并传输到大脑的独特作用。在过去的四分之一世纪里，毛细胞是如何完成这一独特功能的一直是激烈而富有成果的研究的焦点。已经确定了一些分子参与者，但是转导通道本身和许多相关转导复合物的身份仍然难以捉摸。毛细胞转导复合物的分子鉴定滞后是由于每个感觉器官的毛细胞数量较少（2- 16000），而每个细胞的转导分子很少（50-100）。为了克服这些困难，我们提出了一种新颖而引人注目的方法，该方法将利用小鼠耳蜗机械转导获得的精确时间和区域发育模式。在这个项目的第一部分，我们将确定毛细胞何时成为机械敏感，作为耳蜗发育阶段和位置的功能，我们将表征机械传导特性的张力差异。我们假设毛细胞机械感觉所需的基因将在转导开始时富集。因此，我们将分析各种候选分子在Corti器官发育过程中的基因表达时空格局。具有与机械敏感性获得模式平行的表达模式的分子将被确定为转导候选分子。为了确定候选分子的确切作用，我们将抑制它们的功能表达，并在体外和体内试验中使用毛细胞和听觉功能的破坏。特别是，我们将使用RNA干扰和显性阴性抑制和实验来抑制发育中的毛细胞的机械转导。为了检测基因在体内的功能，我们将产生可诱导的、候选突变基因的毛细胞表达，并检测听觉功能的丧失。摘要：本研究旨在确定耳聋和平衡障碍的遗传基础。我们将在发育过程中检查正常内耳的感觉细胞，以确定细胞何时开始起作用以及哪些基因被打开。我们将使用几种遗传技巧来阻止这些基因的活动，并检查它们对听力的影响。听力功能的丧失将确认哪些基因是正常听力所必需的，哪些基因在突变时可能导致遗传性耳聋。

DESCRIPTION (provided by applicant): Hair cells of the inner ear have the exclusive role of converting head movements and sound into electrical signals that are transmitted to the brain. How hair cells accomplish this unique function has been the focus of intense and fruitful investigation over the last quarter century. A few of the molecular players have been identified, however the identity of the transduction channel itself and much of the associated transduction complex remains elusive. The lag in molecular identification of the hair cell transduction complex is a consquence of the low number of hair cells per sensory organ (2-16 thousand) and the few tranduction molecules per cell (50-100). To circumvent these difficulties we propose a novel and compelling approach that will take advantage of the precise temporal and regional developmental pattern in the acquisition of mechanotransduction in the mouse cochlea. In the first part of this project we will determine when hair cells become mechanosensitive as a function of developmental stage and position along the cochlea and we will characterize tonotopic differences in the properties of mechanotransduction. We hypothesize that genes required for hair cell mechanosensation will be enriched around the time of transduction onset. Thus, we will analyze the spatio-temporal pattern of gene expression for various candidate molecules during the development of the Organ of Corti. Molecules with expression patterns that parallel the pattern of acquisition of mechanosensitivity will be identifed as transduction candidates. To determine the precise role of the candidate molecules we will inhibit their functional expression and use in vitro and in vivo assays for disruption of hair cell and auditory function. In particular, we will use RNA interference and dominant- negative inhibition and assay for suppression of mechanotransduction in developing hair cells. To examine gene function in vivo we will generate inducible, hair cell expression of mutant candidate genes and assay for loss of auditory function. Lay summary: This study is designed to identify the genetic basis of deafness and balance disorders. We will examine the sensory cells of the normal inner ear during development to identify when the cells begin to function and which genes are turned on. We will use several genetic tricks to block the activity of those genes and examine their effect on hearing. Loss of hearing function will confirm which genes are necessary for normal hearing and which genes may cause genetic deafness when mutated.