Molecular mechanisms underlying morphogenesis of the tectorial membrane

项目总结/摘要 覆膜（TM）是位于Corti器官上方的细胞外基质（ECM）。TM游戏 在频率选择、传播和声波放大中起重要作用。TM畸形 会导致遗传性听力缺陷由于TM是一种非细胞结构，其独特的性质源于 矩阵结构TM表现出复杂的超微结构特征和特定领域的模式， 矩阵组织然而，组织特定矩阵架构的机制 细胞外是未知的。它是由其分子组成和/或组织模式决定的吗？我们 观察到需要通过糖基磷脂酰肌醇（GPI）-锚表面束缚α-tectorin/TECTA 以防止分泌的TM组分扩散到中阶的腔空间中 TM-产生细胞顶端表面的基质。TECTA的释放在细胞的生长中起着关键作用， TM层。我们的体外试验表明，TECTA是从生产细胞释放的多个 这些不同的机制释放的不同形式的TECTA显示出独特的 多聚化活动。在这个建议中，我们将确定TECTA的分子机制， 协调特定TM架构的组织。我们将描述分子动力学 在基质成熟过程中。我们的研究结果将首次证明复杂的ECM结构是如何 在分子水平上在细胞外空间建立和成熟。这将提供新的见解， 形态发生的过程以及遗传性和年龄相关性听力缺陷的机制。

PROJECT SUMMARY/ABSTRACT The tectorial membrane (TM) is an extracellular matrix (ECM) that lies over the organ of Corti. The TM plays important roles in frequency selection, propagation, and amplification of sound waves. Malformation of the TM causes hereditary hearing deficits. Since the TM is an acellular structure, its unique properties arise from the matrix architecture. The TM exhibits sophisticated ultrastructural features and domain-specific patterns of matrix organization. However, the mechanisms by which the specific matrix architectures are organized outside of cells are unknown. Is it determined by its molecular composition and/or mode of organization? We observed that surface-tethering of a-tectorin/TECTA via a glycosylphosphatidylinositol (GPI)-anchor is required to prevent diffusion of secreted TM components into the luminal space of the scala media and to form the TM matrix on the apical surface of TM-producing cells. The release of TECTA plays a critical role in the growth of the TM layers. Our in vitro assays show that TECTA is released from the producing cells by multiple mechanisms and that the different forms of TECTA released by these distinct mechanisms show unique multimerization activities. In this proposal, we will determine the molecular mechanism by which TECTA mediates the organization of specific TM architecture. We will characterize molecular dynamics that occur during the matrix maturation. Our results will provide the first evidence of how a complex ECM structure is established and matures in the extracellular space at the molecular level. This will provide novel insights into the process of morphogenesis as well as the mechanism of hereditary and age-related hearing deficits.