Molecular mechanisms underlying morphogenesis of the tectorial membrane

项目摘要/摘要 覆盖膜(TM)是一种位于Corti器官上的细胞外基质(ECM)。TM发挥作用 在声波的频率选择、传播和放大方面发挥重要作用。TM畸形 会导致遗传性听力障碍。由于TM是一种无细胞结构，其独特的性质源于 矩阵架构。TM显示出复杂的超微结构特征和特定于领域的模式 矩阵组织。然而，特定矩阵体系结构的组织机制 细胞外是未知的。它是由其分子组成和/或组织方式决定的吗？我们 观察到需要通过糖基磷脂酰肌醇(GPI)锚点对a-tectorin/TECTA进行表面锚定 以防止分泌的TM成分扩散到中阶的管腔空间并形成TM 在TM产生细胞的顶面上有基质。TECTA的释放在肿瘤的生长中起着至关重要的作用 TM层。我们的体外测试表明，TECTA从生产细胞中释放出 这些不同的机制释放的不同形式的TECTA显示出独特的 多聚体活动。在这个提案中，我们将确定TECTA的分子机制 协调特定TM架构的组织。我们将描述发生的分子动力学 在基质成熟过程中。我们的结果将为ECM结构的复杂程度提供第一个证据 在分子水平上在细胞外空间建立和成熟。这将为我们提供新的见解 形态发生的过程以及遗传性和年龄相关性听力障碍的机制。

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.