Microtubule-mediated mechanisms underlying hair cell development and deafness

毛细胞发育和耳聋的微管介导机制

基本信息

批准号：
10116360
负责人：
Xiaowei Lu
金额：
$ 45.06万
依托单位：
UNIVERSITY OF VIRGINIA
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-03-01 至 2025-02-28
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10116360
关键词：
Actins Alleles Americas Apical Auditory Cell Culture Techniques Cilia Cochlea Cochlear duct Cytoskeleton Data Defect Development Disease Ear Economic Burden Embryonic Development Ensure Environment Environmental Risk Factor Epithelial Equilibrium Foundations G-Protein Signaling Pathway GTP-Binding Proteins Genes Genetic Guanine Nucleotide Exchange Factors Hair Hair Cells Hearing Heterotrimeric GTP-Binding Proteins Human Image In Vitro Inherited Injury Kinocilium Knock-out Knockout Mice Knowledge Lateral Ligands Link Maintenance Mammals Medial Mediating Medical Membrane Microtubules Molecular Morphogenesis Morphology Motor Mutant Strains Mice Names Natural regeneration Organelles Pathway interactions Pattern Peripheral Phenotype Phosphatidylinositols Phosphotransferases Positioning Attribute Proteins Publishing Regulation Role Scaffolding Protein Sensorineural Hearing Loss Sensory Hair Signal Pathway Signal Transduction Signaling Protein Stereocilium Structure Testing Tissues Transducers WNT Signaling Pathway Work base beta catenin cellular microvillus conditional knockout deafness design disability gain of function genetic deafness hair cell regeneration hearing impairment in vivo insight loss of function mechanotransduction migration morphogens mutant novel permanent hearing loss planar cell polarity polarized cell programs protease-activated receptor 3 protein activation receptor recruit relating to nervous system repaired sensor social sound stem cell technology targeted treatment

项目摘要

The actin-based stereociliary bundle (or hair bundle) on the apex of auditory hair cells serves the critical function of converting sound energy to electric signals. Defects in hair bundle development and maintenance due to genetic and environmental factors are a leading cause for sensorineural deafness. A long-term objective of this work is to gain a mechanistic understanding of hair bundle morphogenesis programs, including secreted morphogens and their downstream signaling effectors and cytoskeletal regulators. Formation of the V-shaped hair bundle is integrally linked to planar polarization of the hair cell apical cytoskeleton, which is initiated by the peripheral migration of the kinocilium, the hair cell primary cilium. Recent advances demonstrate that hair cell intrinsic planar polarity, which we name iPCP to be concise, is regulated by several planar polarized, cell- intrinsic signaling modules and microtubule motors. At the tissue-level, the non-canonical Wnt/Planar Cell Polarity (PCP) pathway aligns hair cell orientation along the medial-lateral (or neural-abneural) axis of the cochlear duct. While disrupted tissue-level PCP signaling causes hair bundle misoriention, defective iPCP signaling results in both misoriented and misshapen hair bundles with a mispositioned kinocilium. Despite its importance for hair bundle morphogenesis, how iPCP is regulated by developmental signals and how iPCP and PCP signaling are integrated remain poorly understood. To fill these knowledge gaps, this application leverages our recent exciting discoveries and aims to elucidate the mechanisms by which a novel Wnt/G protein signaling pathway coordinately controls iPCP and PCP during hair bundle morphogenesis. While Wnt/β-catenin and Wnt/PCP pathways have been extensively studied, little is known about the in vivo function and mechanisms of Wnt/G protein signaling. Our aims are built on a strong foundation of preliminary data, showing that Wnt ligands secreted by the cochlear epithelium activate heterotrimeric G protein and PI3K signaling to control both iPCP and PCP. We have identified genes required for G protein activation in the cochlea, providing clues to the molecular mechanism. We propose to use gain- and loss-of-function alleles in vivo, ex vivo cochlear explants and cell culture studies in vitro to define critical components of the Wnt/G protein pathway and its integration with the Wnt/PCP pathway. In Aim 1, we will delineate the signal transduction machinery of the Wnt/G protein pathway by determining the roles of specific Wnt ligand, Frizzled receptors and downstream signal transducers. In Aim 2, we investigate the role of the iPCP component Par3 in Wnt-induced G protein activation. In Aim 3, we will test whether Wnt/G protein signaling is regulated by multiple G protein GEFs during cochlear morphogenesis. Ultimately, insights into this new Wnt signaling pathway may facilitate devising rational therapies to stimulate hair bundle repair following injury and to regenerate auditory hair cells through stem cell technologies.

听觉毛细胞顶端基于肌动蛋白的静纤毛束（或发束）发挥着关键作用将声能转换为电信号的功能缺陷。由于遗传和环境因素是感音神经性耳聋的一个长期目标。这项工作的目的是获得对发束形态发生程序的机械理解，包括分泌的形态发生素及其下游信号效应器和细胞骨架调节器 V 形的形成。毛束与毛细胞顶端细胞骨架的平面极化紧密相关，这是由动纤毛（毛细胞初级纤毛）的外周迁移最近的进展表明毛细胞。固有的平面极性，我们将其命名为 iPCP，是由几个平面极化、细胞极化调节的。内在信号模块和微管马达在组织水平上，非规范的 Wnt/平面细胞。极性 (PCP) 通路沿着毛细胞的内侧-外侧（或神经-神经外）轴对齐毛细胞方向组织水平 PCP 信号传导中断会导致毛束定向错误，导致 iPCP 缺陷。尽管有动纤毛，但信号传导会导致发束定向错误和畸形。对于发束形态发生的重要性、iPCP 如何受发育信号调节以及 iPCP 如何进行和 PCP 信令的集成仍然知之甚少，为了填补这些知识空白，该应用程序。利用我们最近令人兴奋的发现，旨在阐明新型 Wnt/G 的机制蛋白信号通路在发束形态发生过程中协调控制 iPCP 和 PCP。 Wnt/β-catenin 和 Wnt/PCP 通路已被广泛研究，但对其体内功能知之甚少以及Wnt/G蛋白信号传导的机制。我们的目标建立在初步数据的坚实基础上，这些数据表明 Wnt 配体由耳蜗上皮激活异三聚体 G 蛋白和 PI3K 信号传导来控制 iPCP 和 PCP We。已经确定了耳蜗中 G 蛋白激活所需的基因，为分子生物学提供了线索我们建议使用体内、离体耳蜗外植体和细胞的功能获得和丧失等位基因。体外培养研究以确定 Wnt/G 蛋白途径的关键成分及其与 Wnt/PCP 通路在目标 1 中，我们将描述 Wnt/G 蛋白通路的信号转导机制。通过确定特定 Wnt 配体、Frizzled 受体和下游信号转导器的作用。 2，我们研究 iPCP 成分 Par3 在 Wnt 诱导的 G 蛋白激活中的作用。在目标 3 中，我们将研究。测试耳蜗形态发生过程中 Wnt/G 蛋白信号传导是否受到多个 G 蛋白 GEF 的调节。最终，对这种新的 Wnt 信号通路的深入了解可能有助于设计合理的疗法来刺激损伤后的发束修复，并通过干细胞技术再生听觉毛细胞。