GIPC3, multifunctional myosin adaptor in mammalian auditory hair cells

GIPC3，哺乳动物听毛细胞中的多功能肌球蛋白适配器

• 批准号: 10188498
• 负责人: Gregory I Frolenkov
• 金额: $ 55.78万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-10 至 2025-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10188498
• 关键词: Actins; Adopted; Affect; Age; Age-Months; Ankle; Apical; Architecture; Auditory; Auditory system; Belief; Binding; Biochemical; Biochemistry; C-terminal; CDH23 gene; Cadherin Domain; Caliber; Cell physiology; Cells; Cellular Structures; Complex; Consensus; Coupling; Custom; Data; Development; Dimerization; EPS8 gene; Endocytosis; Family; Family member; Hair; Hair Cells; Hearing; Human; Inherited; Inner Hair Cells; Knowledge; Label; Labyrinth; Link; MYO7A gene; Mechanics; Mediating; Molecular; Motor; Mouse Strains; Mus; Mutation; Myosin ATPase; N-terminal; Outcome Study; Patients; Phenotype; Physiological; Point Mutation; Positioning Attribute; Prevention; Protein Family; Proteins; Receptor Activation; Reporting; Rest; Role; Shapes; Site; Structure; Surface; Synaptic Transmission; Therapeutic; Time; Ubiquitin; Vesicle; WHRN gene; base; cell type; deaf; deafness; dimer; hearing impairment; in vivo; insight; live cell imaging; mechanotransduction; member; mouse model; mutant; myosin VI; myosin XVA; nanobodies; normal hearing; novel; prevent; receptor; receptor binding; response; structural biology; therapy development; trafficking; two-photon; uptake

GIPC3, a member of Gα-Interacting Protein, C-terminus (GIPC) family, is known to be essential for hearing. Eleven mutations in GIPC3, spread throughout its three structural domains, cause inherited autosomal recessive hearing loss. However, the molecular basis for GIPC3 function in the auditory system and the mechanisms by which these human mutations result in hearing loss are unknown. We have recently determined the structure of GIPC3 bound to a prototypical receptor and determined the molecular mechanism of GIPC3 activation and its subsequent binding to MYO6, the unconventional myosin that is expressed in the auditory hair cells and is essential for hearing. These biochemical and structural studies allowed us to predict the effects of known deafness-related mutations in GIPC3 on its activation and MYO6 binding. We have generated two new mouse models, one that is lacking functional GIPC3 and another one with a W301X point mutation in Gipc3 that corresponds to a mutation with the most severe auditory phenotype in humans. This study will explore the central hypothesis that GIPC3 has a dual role in the auditory hair cells. We hypothesize that in stereocilia GIPC3 is involved in shaping mechanotransduction and hair bundle structure through its interactions with CDH23/myosin-VIIa and myosin-XVa, respectively. In the cell body, GIPC3 is essential for apical endocytosis at the pericuticular neckless region due to its interaction with myosin-VI. All these functions are crucial for normal hearing. However, the exact molecular mechanisms that determine the resting tension in the mechanotransduc- tion machinery as well as gradation of stereocilia heights and diameters in the auditory hair cell bundles are still enigmatic. Likewise, very little is known about molecular mechanisms and even the role of pericuticular neckless endocytosis in the hair cell function. The expected outcomes of this study are to uncover (a) the precise mechanism of deafness associated with GIPC3 deficiency and (b) the physiological role of GIPC3 in hair cell functions, especially in mechanotransduction, formation of the hair bundle architecture, and endocytosis at the pericuticular neckless. Deciphering the function of GIPC3 protein and its known mutations is a critical step towards the development of therapies for the treatment and/or prevention of GIPC3-dependent deafness and hearing loss.

GIPC3 是 Gα 相互作用蛋白 C 端 (GIPC) 家族的成员，已知对于 GIPC3 的 11 种突变分布在其三个结构域中，导致遗传性听力。 然而，GIPC3 听觉功能的分子基础。 这些人类突变导致听力损失的系统和机制尚不清楚。 最近确定了与原型受体结合的 GIPC3 的结构，并确定了 GIPC3 激活及其随后与非常规分子 MYO6 结合的分子机制 肌球蛋白在听觉毛细胞中表达，对于听力至关重要。 结构研究使我们能够预测 GIPC3 中已知的耳聋相关突变对其的影响 我们已经生成了两种新的小鼠模型，其中一种缺乏功能。 GIPC3 和另一个在 Gipc3 中具有 W301X 点突变的突变，对应于具有 这项研究将探讨 GIPC3 的中心假设。 我们发现，在静纤毛中，GIPC3 参与塑造。 通过与 CDH23/肌球蛋白-VIIa 的相互作用实现机械转导和发束结构 肌球蛋白-XVa 在细胞体中，GIPC3 对于表皮周的顶端内吞作用至关重要。 由于其与肌球蛋白-VI 相互作用，所有这些功能对于正常听力至关重要。 然而，决定机械转导中静息张力的确切分子机制 化机械以及听觉毛细胞束中静纤毛高度和直径的分级 同样，人们对分子机制甚至作用知之甚少。 毛细胞功能中的角质周无颈内吞作用。 揭示 (a) 与 GIPC3 缺乏相关的耳聋的精确机制以及 (b) GIPC3 在毛细胞功能中的生理作用，特别是在机械转导、毛发形成中 束结构和角质周颈内吞作用破译 GIPC3 的功能。 蛋白质及其已知突变是开发治疗方法的关键一步 和/或预防GIPC3依赖性耳聋和听力损失。