Structural Basis of Outer Hair Cell Function

外毛细胞功能的结构基础 摘要 在过去的二十年里，我们对外毛细胞(OHC)结构和 功能。例如，我们知道，耳蜗放大与OHC快速运动有关，这是 由数千个拷贝的构象变化在质膜中产生的力驱动 整合膜蛋白Prestin。我们知道，这些力量的利用和方向与 OHC的长轴由皮质细胞骨架组成，一个由肌动蛋白细丝交叉而成的二维各向异性网络- 由位于整个OHC侧质膜下的幽灵蛋白连接，我们知道这是可能的 因为质膜与细胞骨架肌动蛋白细丝之间有成千上万的结构“支柱”相连。我们 然而，仍然不知道这些支柱的性质。我们不知道它们是如何工作的，或者它们是否 在调节预制力方面的任何作用。我们也不知道 通过调节细胞骨架组织及其支柱介导的连接来控制OHC的长度和运动性 质膜。这项建议的目标是填补我们对OHC结构和 功能，这是我们寻求了解耳蜗功能的关键一步，涉及OHC变化的功能障碍 通过解决以下具体目标，形成和保护应对过度刺激的机制： 1)证明GLUT5、Dematin和Adducin是OHC支柱的主要成分，2) 确定Profilin和Cofilin介导的肌动蛋白聚合和解聚的作用 3)决定RhoA/ROCK-PKC的作用 OHC长度和运动性的调控途径。

Structural Basis of Outer Hair Cell Function Abstract The last two decades witnessed a huge increase in our understanding of outer hair cell (OHC) structure and function. We know, for example, that cochlear amplification is associated with OHC fast motility, which is driven by forces generated in the plasma membrane by conformational changes in thousands of copies of the integral-membrane protein prestin. We know that these forces are harnessed and oriented parallel to the OHC's major axis by the cortical cytoskeleton, a two-dimensional anisotropic network of actin filaments cross- linked by spectrin that underlies the entire OHC lateral plasma membrane, and we know that that is possible because the plasma membrane is linked to cytoskeletal actin filaments by thousands of structural "pillars". We still don't know, however, the nature of these pillars. We don't know how they work, or whether they have any role in the regulation of the prestin-generated force. We don't know either the molecular mechanisms that control OHC length and motility by regulating cytoskeletal organization and its pillar-mediated connection to the plasma membrane. The goal of this proposal is to fill these gaps in our knowledge of OHC's structure and function, a crucial step in our quest to understand cochlear function, malfunctions that involve changes in OHC shape, and protective mechanisms in response to over stimulation, by addressing the following Specific Aims: 1) Demonstrate that proteins GLUT5, Dematin and Adducin are major components of OHC pillars, 2) Determine the role of actin polymerization and depolymerization induced by profilin- and cofilin-mediated signals in the regulation of OHC length and motility, and 3) Determine the role of the RhoA/ROCK-PKC pathway in the modulation of OHC length and motility.