Cytoskeletal dynamics in stereocilia maintenance

描述(申请人提供)：进行性听力损失是一种常见的人类健康问题，通常源于内耳感觉毛细胞的丧失或功能障碍。肌动蛋白 蛋白质是毛细胞结构和功能的核心；因此，了解细胞骨架维持的分子机制是考虑合理设计治疗年龄相关性或噪声性听力损失的关键步骤。肌动蛋白和肌动蛋白是两种截然不同但密切相关的肌动蛋白亚型，它们各自对丝状肌动蛋白的数量有贡献。 在立体纤毛中。我们之前已经证明，毛细胞缺乏任何一种肌动蛋白亚型的小鼠都会形成正常的立体纤毛，但会发展成不同形式的进行性听力损失。这表明-肌动蛋白和-肌动蛋白各自对立体纤毛的稳定性有独特的贡献。这项建议集中在立体纤毛中肌动蛋白生物学的两个方面。在目标1中，我们将使用现有的条件性肌动蛋白和肌动蛋白基因敲除小鼠品系和新开发的转基因肌动蛋白报告品系来评估体内立体纤毛中肌动蛋白的动力学。在目标2中，我们将使用细胞生物学和生化方法来确定肌动蛋白捆绑蛋白Fasin 2与肌动蛋白和肌动蛋白之间的不同相互作用是否有助于不同的立体纤毛维持机制。总之，这些目标的完成将支持在立体纤毛维持过程中肌动蛋白调节的新模式。从长远来看，我们将使用这项建议中建立的同一套通用平台来评估其他导致耳聋的突变肌动蛋白结合蛋白在分子、细胞和小鼠水平上调节立体纤毛肌动蛋白动力学的作用。 与公共卫生相关：与年龄相关的听力损失是人类最常见的听力损害形式，通常是由内耳中专门的感觉细胞退化引起的。这些细胞中的许多依赖于不同种类的肌动蛋白来维持正常的结构和功能。我们建议阐明每种类型的肌动蛋白促进细胞维持的机制，为治疗干预措施的基本设计提供基础。

DESCRIPTION (provided by applicant): Progressive hearing loss is a common human health problem that often stems from the loss or dysfunction of sensory hair cells in the inner ear. Actin proteins are central to hair cell structure and function; consequently, understanding the molecular mechanisms of cytoskeletal maintenance is a key step in considering rationally designed therapies for age-related or noise-induced hearing loss. ¿-Actin and ?-actin, two distinct yet closely related actin isoforms, each contribute to the population of filamentous actin in stereocilia. We have previously shown that mice with hair cells lacking either actin isoform form normal stereocilia, but go on to develop different forms of progressive hearing loss. This suggests that ¿-Actin and ?-actin each make unique contributions to stereocilia stability. This proposal is focused on two aspects of actin biology in stereocilia. In Aim 1, we will use existing conditional ¿-Actin and ?-actin knockout mouse lines and a newly developed transgenic actin reporter line to assess actin dynamics in stereocilia in vivo. In Aim 2, we will use cell biologica and biochemical approaches to determine if differential interactions between the actin bundling protein fascin 2 and ¿-actin and ?-actin contribute to distinct stereocilia maintenance mechanisms. Together, completion of these Aims will support a new model of actin regulation during stereocilia maintenance. In the long term, we will use the same suite of universal platforms established in this proposal to assess the roles of other deafness-causing mutant actin binding proteins in modulating stereocilia actin dynamics at the level of molecules, cells and mice. PUBLIC HEALTH RELEVANCE: Age-related hearing loss is the most common form of hearing impairment in humans and is often caused by degeneration of specialized sensory cells in the inner ear. Many of these cells depend on different kinds of actin proteins for normal structure and function. We are proposing to elucidate the mechanisms through which each type of actin contributes to cell maintenance to provide the foundation for rationale design of therapeutic interventions.