Dissecting Wnt/PCP Signaling in Developing Cochlear Sensory Epithelium

剖析发育中的耳蜗感觉上皮中的 Wnt/PCP 信号转导

• 批准号: 7991348
• 负责人: Xiaowei Lu
• 金额: $ 36.3万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-01 至 2012-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7991348
• 关键词: Actins; Auditory; Biochemical; Biological; Cell Polarity; Cells; Cochlea; Congenital Abnormality; Cytoskeleton; Defect; Development; Diagnosis; Epithelial; Epithelium; Feeds; Genes; Genetic; Goals; Hair; Hair Cells; Human; Mechanics; Molecular; Monomeric GTP-Binding Proteins; Morphogenesis; Mus; Names; Neural Tube Closure; Neural tube; Organ Culture Techniques; Organ of Corti; Pathway interactions; Phosphotransferases; Principal Investigator; Process; Protein Tyrosine Kinase; Proteins; Proteolysis; Receptor Protein-Tyrosine Kinases; Recovery of Function; Research; Role; Sensory; Signal Pathway; Signal Transduction; Signaling Molecule; Stimulus; Structure; Testing; Tissues; base; deafness; hearing impairment; insight; mouse model; novel; programs; repaired; sound

DESCRIPTION (provided by applicant): The actin-based stereocilary bundle (or hair bundle) on the apex of auditory hair cells serves the crucial function of converting sound energy to electric signals. Its staircase structure renders the bundle directionally sensitive to mechanical stimuli. As such, auditory hair bundles must be uniformly oriented for correct sound transduction. Abnormalities in hair bundle structure or orientation cause deafness and hearing impairment. The uniform orientation of auditory hair bundles is a prominent example of epithelial planer cell polarity (PCP), or polarity within the plane of the epithelial sheet. It is controlled by an evolutionarily conserved Wnt/PCP signaling pathway. Disruption of the PCP pathway results in severe developmental defects including neural tube closure defect and hair bundle misorientation, underscoring its critical function in regulating tissue morphogenesis. Despite its importance, the molecular and cellular mechanisms by which the PCP pathway regulates the intricate morphogenetic processes during hair bundle development are still poorly understood. The long-term goal of this research is to understand how PCP signaling directs coordinated remodeling of the hair cell cytoskeleton to form uniformly oriented hair bundles. The primary focus of this project is to dissect the function of protein tyrosine kinase 7 (PTK7), a novel component of the mammalian PCP pathway previously identified in a mouse gene-trap screen. PTK7 encodes a catalytically inactive receptor tyrosine kinase. Mouse models, cochlear organ cultures, and a combination of genetic, biochemical and cell biological approaches will be used to test the central hypothesis that PTK7 deploys both conserved and novel mechanisms to regulate hair bundle orientation. Aim 1 will determine where PTK7 feeds into the conserved PCP pathway. The hypothesis to be tested is that PTK7, via its cytoplasmic kinase domain, interacts with the PCP signaling molecule Dishevelled to activate the small GTPase Rac, leading to cytoskeletal remodeling. Aim 2 will determine the cell-autonomy of PTK7 in the organ of Corti and the role of proteolysis in regulating intra- and inter-cellular signaling activity of PTK7. In Aim 3, novel signaling mechanisms of PTK7 will be explored, first by testing the kinase function of PTK7, followed by isolating novel PTK7 interacting proteins. Understanding PCP signaling mechanisms that control cytoskeletal remodeling during hair bundle development will aid in devising therapies to promote hair cell repair and meaningful functional recovery following repair. Moreover, because the PCP pathway regulates morphogenesis of diverse tissues, including the neural tube, studies of hair cell morphogenesis will likely provide novel insights into the general principles of PCP signaling during tissue morphogenesis, which will facilitate the diagnosis and treatment of many devastating human birth defects.

描述（由申请人提供）：听觉毛细胞顶端的基于肌动蛋白的立体纤毛束（或发束）发挥着将声能转换为电信号的关键功能。其阶梯结构使束对机械刺激定向敏感。因此，听觉毛束必须均匀定向才能正确传导声音。发束结构或方向异常会导致耳聋和听力障碍。听觉毛束的统一方向是上皮平面细胞极性（PCP）或上皮片平面内极性的一个突出例子。它由进化上保守的 Wnt/PCP 信号通路控制。 PCP 通路的破坏会导致严重的发育缺陷，包括神经管闭合缺陷和发束定向错误，强调了其在调节组织形态发生中的关键功能。尽管 PCP 途径很重要，但其在发束发育过程中调节复杂形态发生过程的分子和细胞机制仍知之甚少。这项研究的长期目标是了解 PCP 信号传导如何指导毛细胞细胞骨架的协调重塑，以形成均匀定向的发束。该项目的主要重点是剖析蛋白酪氨酸激酶 7 (PTK7) 的功能，这是先前在小鼠基因陷阱筛选中发现的哺乳动物 PCP 途径的新成分。 PTK7 编码催化失活受体酪氨酸激酶。小鼠模型、耳蜗器官培养以及遗传、生化和细胞生物学方法的组合将用于测试中心假设，即 PTK7 采用保守和新颖的机制来调节发束方向。目标 1 将确定 PTK7 在何处进入保守的 PCP 途径。待测试的假设是PTK7通过其细胞质激酶结构域与PCP信号分子Disheveled相互作用以激活小GTPase Rac，导致细胞骨架重塑。目标 2 将确定 PTK7 在 Corti 器官中的细胞自主性以及蛋白水解在调节 PTK7 细胞内和细胞间信号传导活性中的作用。在目标 3 中，将探索 PTK7 的新信号传导机制，首先通过测试 PTK7 的激酶功能，然后分离新的 PTK7 相互作用蛋白。了解在发束发育过程中控制细胞骨架重塑的 PCP 信号传导机制将有助于设计促进毛细胞修复和修复后有意义的功能恢复的疗法。此外，由于PCP途径调节包括神经管在内的多种组织的形态发生，因此对毛细胞形态发生的研究可能会为组织形态发生过程中PCP信号传导的一般原理提供新的见解，这将有助于许多毁灭性人类出生的诊断和治疗缺陷。