Role of myosin 1c in adaptation in the inner ear

肌球蛋白 1c 在内耳适应中的作用

• 批准号: 7523068
• 负责人: LYNNE M COLUCCIO
• 金额: $ 59.4万
• 依托单位: BOSTON BIOMEDICAL RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7523068
• 关键词: ATP phosphohydrolase; Accounting; Actins; Affect; Amino Acids; Animals; Auditory; Binding; Biochemical; Biochemistry; Biological Assay; Calcium; Calcium ion; Calmodulin; Cell physiology; Cells; Class; Complex; Cytoskeleton; Diagnostic; Equilibrium; Exhibits; Filament; Goals; Hair Cells; Head Movements; Hearing; Hearing problem; In Vitro; Inner Hair Cells; Kinetics; Knock-in Mouse; Knowledge; Laboratories; Labyrinth; Lead; Link; Measures; Mechanics; Modeling; Molecular; Molecular Motors; Motor; Motor Activity; Mus; Mutate; Mutation; Myosin ATPase; Myosin Type I; Nerve; Personal Satisfaction; Potassium; Process; Property; Proteins; Range; Rate; Recovery; Rest; Role; Sensory Hair; Stereocilium; Stimulus; Testing; Thinking; Vertigo; Vestibular Hair Cells; Weight-Bearing state; base; cell motility; design; extracellular; hearing impairment; human CDH23 protein; in vivo; insight; mutant; prevent; protocadherin 19; response; single molecule; sound; vibration

DESCRIPTION (provided by applicant): The broad, long-range goal of this study is to determine the molecular mechanism of hearing and balance. Actin-filled projections, or stereocilia, on the sensory hair cells of the inner ear convert force produced by sounds and mechanical vibrations into nerve impulses. The prevailing model for mechanotransduction, thought to be well-conserved for both cochlear and vestibular hair cells, is one in which neighboring stereocilia connected by extracellular filaments called tip links, deflect in response to stimuli, thereby causing the opening or closing of transduction channels. The channels are attached to an adaptation-motor complex, which controls tip-link tension. During an excitatory stimulus, tension is initially high, opening channels; the motor complex then slips down the actin cytoskeleton, reducing tip-link tension and allowing the channels to close. By contrast, during a negative stimulus, tension is initially low and channels close; the motor complex then ascends the cytoskeleton, restoring the resting tension and reopening the channels. Localization of the molecular motor, myosin 1c (Myo1c) at strategic places in the stereocilia; and studies using mice expressing a mutant Myo1c that can be selectively inhibited have shown Myo1c's involvement in this process known as adaptation (Holt et al., 2002; Stauffer et al., 2005). Adaptation allows hair cells under prolonged stimuli to remain sensitive to new stimuli. The goal of this proposal is to determine how Myo1c supports specific aspects of adaptation by measuring adaptation in mice expressing Myo1c mutants with defined molecular properties. Myo1c mutants will include (i) those that affect the ability of Myo1c to adapt to mechanical load, a property predicted for Myo1c from previous studies in this laboratory (Batters et al., 2004a; 2004b); and (ii) those with aberrant sensitivity to Ca2+, which regulates Myo1c and adaptation. The specific aims are: to express in vitro and characterize the biochemical and mechanical properties of Myo1c mutants using ATPase assays, motility assays, kinetic analyses and single-molecule mechanical studies. Next, knock-in mice expressing these mutant Myo1c molecules will be generated and adaptation will be measured in hair cells from the knock-in mice. The combined in vitro and animal studies are expected to provide critical, new insight into the molecular mechanism of Myo1c and its role in adaptation. This knowledge could ultimately lead to the design of rational diagnostics and therapies to treat diseases of hearing and/or balance. The proposed study focuses on the molecular motor protein, Myo1c, which is implicated as the adaptation-motor complex in the hair cells of the inner ear. Determining the biochemical and biophysical properties of key components of the transduction apparatus in hair cells, like Myo1c, and its role in adaptation are of fundamental importance to revealing the molecular mechanisms of hearing and balance, so that new and appropriate diagnostics and therapies to prevent or treat hearing loss and vertigo can be developed.

描述（由申请人提供）：本研究的广泛，远程目标是确定听力和平衡的分子机制。在内耳的感觉毛细胞上充满肌动蛋白填充的投影或立体胶质，将声音和机械振动产生的力转化为神经冲动。机械传输的盛行模型，被认为对人工耳蜗和前庭毛细胞保存良好，是一种被称为尖端链接的邻近立体胶质，从而响应刺激，从而导致转移通道的开口或闭合。通道连接到适应性运动复合物，该复合物控制尖端连接张力。在兴奋性刺激期间，张力最初是较高的开放通道。然后，电动机复合物将肌动蛋白细胞骨架滑落，减少尖端连接张力并允许通道关闭。相比之下，在负面刺激期间，张力最初是低的，通道关闭。然后，电动机复合物登上细胞骨架，恢复静止张力并重新打开通道。分子运动的定位，肌球蛋白1c（myo1c）在立体核心的战略位置；以及使用表达突变体Myo1c的小鼠可以选择性抑制的研究表明，Myo1c参与了这种过程称为适应性（Holt等，2002; Stauffer等，2005）。适应使长时间刺激下的毛细胞对新刺激保持敏感。该建议的目的是通过测量表达具有定义分子特性的MyO1c突变体的小鼠的适应性来确定MyO1c如何支持适应的特定方面。 Myo1c突变体将包括（i）那些影响MyO1c适应机械负荷的能力的突变体，这是该实验室先前研究所预测的属性（Batters等，2004a; 2004b）; （ii）那些对Ca2+异常敏感的人，调节MyO1c和适应。具体目的是：使用ATPase分析，运动性测定，动力学分析和单分子机械研究表达体外并表征Myo1c突变体的生化和机械性能。接下来，将产生表达这些突变体Myo1c分子的敲入小鼠，并将在敲入小鼠的毛细胞中测量适应性。预期在体外和动物研究中将提供有关Myo1c的分子机制及其在适应中的作用的关键，新的见解。这些知识最终可能导致设计理性诊断和疗法，以治疗听力和/或平衡的疾病。拟议的研究集中于分子运动蛋白MyO1c，该蛋白与内耳毛细胞中的适应运动复合物有关。确定毛细胞中转导设备的关键组成部分的生化和生物物理特性，例如Myo1c，其在适应性中的作用对于揭示听力和平衡的分子机制至关重要，从而可以开发出新的和适当的诊断和治疗诊断和治疗的诊断和疗法。