Structural Basis of Outer Hair Cell Function

外毛细胞功能的结构基础

• 批准号: 7878561
• 负责人: FEDERICO KALINEC
• 金额: $ 38.27万
• 依托单位: HOUSE RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7878561
• 关键词: Actins; Address; Affinity; Architecture; Basilar Membrane; Binding; Cell Shape; Cell membrane; Cell physiology; Cells; Cellular Structures; Complement; Confocal Microscopy; Cytoplasmic Protein; Cytoskeletal Modeling; Cytoskeleton; Data; Electron Microscopy; Family suidae; GLUT-5 protein; Goals; Hearing; Human; Immunoprecipitation; In Vitro; Integral Membrane Protein; Knowledge; Label; Lateral; Length; Light; Link; Mass Spectrum Analysis; Mediating; Methods; Microfilaments; Microscopy; Modification; Molecular; Mus; Nature; Organ; Organ of Corti; Outer Hair Cells; Pathway interactions; Phosphorylation; Proteins; Recruitment Activity; Regulation; Role; Sensorineural Hearing Loss; Sensory; Signal Transduction; Spectrin; Speed; Stereocilium; Structure; Techniques; Testing; Video Microscopy; Work; adducin; base; cell motility; cofilin; crosslink; deafness; depolymerization; driving force; hearing impairment; in vivo; insight; monomer; mouse model; polymerization; pressure; profilin; rat Pres protein; relating to nervous system; response; sound; two-dimensional

DESCRIPTION (provided by applicant): 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. Structural and/or functional damage of the organ of Corti is the major cause of sensorineural hearing loss afflicting millions of people around the world. The exquisite architecture of the organ of Corti is uniquely adapted to support an enormous range of input sound pressures, and outer hair cells (OHCs) are unique in having their body length directly influencing important aspects of the micromechanics of this organ. For example, minute changes in OHC length can dynamically adjust the operating point of the mechano-sensory apparatus hosted in the cell stereocilia and/or the local resonance of the basilar membrane. Changes in OHC length, known as "OHC motility", are thought to be essential for cochlear amplification. Despite their importance, many gaps exist in our knowledge of the structure and function of OHCs. Filling these gaps would be an important step towards a better understanding of cochlear function, malfunctions that involve changes in OHC shape, and protective mechanisms activated in response to overstimulation. We are confident that accomplishing the aims of the present proposal will provide essential information about the structure of OHCs and the role of the cytoskeleton in the regulation of OHC length and motility, as well as critical insights into the basic mechanisms of both normal human hearing and deafness.

描述（由申请人提供）：过去二十年见证了我们对外毛细胞（OHC）结构和功能的理解的巨大增长。例如，我们知道，耳蜗放大与 OHC 快速运动相关，而 OHC 快速运动是由质膜中数千个整合膜蛋白 prestin 拷贝的构象变化产生的力驱动的。我们知道，这些力被皮质细胞骨架利用并平行于 OHC 的主轴定向，皮质细胞骨架是由位于整个 OHC 侧质膜下方的血影蛋白交联的肌动蛋白丝的二维各向异性网络，我们知道这是可能的因为质膜通过数千个结构“柱”与细胞骨架肌动蛋白丝相连。然而，我们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，也不知道它们是否在调节 prestin 产生的力中发挥任何作用。我们也不知道通过调节细胞骨架组织及其与质膜的支柱介导的连接来控制 OHC 长度和运动的分子机制。该提案的目标是通过解决以下问题来填补我们对 OHC 结构和功能的认识空白，这是我们寻求了解耳蜗功能、涉及 OHC 形状变化的功能障碍以及应对过度刺激的保护机制的关键一步。以下具体目标：1) 证明蛋白质 GLUT5、Dematin 和 Adducin 是 OHC 支柱的主要组成部分，2) 确定 profilin 诱导的肌动蛋白聚合和解聚的作用，以及cofilin 介导的信号在 OHC 长度和运动的调节中，3) 确定 RhoA/ROCK-PKC 通路在 OHC 长度和运动调节中的作用。柯蒂氏器的结构和/或功能损伤是导致全世界数百万人患有感音神经性听力损失的主要原因。柯蒂氏管的精致结构独特地适合支持大范围的输入声压，而外毛细胞 (OHC) 的独特之处在于其体长直接影响该器官微观力学的重要方面。例如，OHC 长度的微小变化可以动态调整细胞静纤毛中的机械感觉装置的工作点和/或基底膜的局部共振。 OHC 长度的变化（称为“OHC 运动性”）被认为对于耳蜗放大至关重要。尽管它们很重要，但我们对 OHC 的结构和功能的了解仍存在许多空白。填补这些空白将是更好地了解耳蜗功能、涉及 OHC 形状变化的功能障碍以及因过度刺激而激活的保护机制的重要一步。我们相信，实现本提案的目标将提供有关 OHC 结构和细胞骨架在 OHC 长度和运动调节中的作用的重要信息，以及对正常人类听力和听力的基本机制的重要见解。耳聋。