Matrix Otopathology

描述（由申请人提供）：耳蜗内的特化上皮细胞和支持细胞与细胞外基质密切相关。其中一种基质，基底膜，利用IV型胶原蛋白形成一种独特的蛋白质晶格，其他基质蛋白与之结合。在发育过程中，基底膜在细胞迁移和细胞成熟中起着关键作用，而在成熟组织中，基底膜参与细胞粘附、极化和渗透过程。基底膜在成熟耳蜗中的作用仍有待充分描述。然而，糖尿病、系统性红斑狼疮、老年性衰老和阿尔波特综合征的动物模型表现出异常厚的毛细血管基底膜和听觉功能障碍。阿尔波特综合征的动物模型特别有趣，因为它是由编码IV型胶原蛋白的基因突变引起的。目前的建议确定增厚的毛细血管基底膜是如何导致听觉功能异常的。通过测定基底膜积累对周围听觉功能的影响，探讨基底膜异常与听力损失之间的关系；评估缺氧对基底膜积累的相关反应；通过抑制毛细血管基底膜的积累改善缺氧和听觉功能障碍。我们提出实验来验证两个假设的有效性：1)审判组织基底膜异常导致耳蜗代谢稳态恶化，从而降低耳蜗功能。这一假设是通过强烈但无害的声音刺激消耗大脑能量储备来验证的。暴露后，测量外周听觉功能的各个方面以及血管纹的电化学和离子传输特性，以确定纹和鳞状介质稳态的变化。2)基底膜蛋白的积累可上调与缺氧相关的反应，从而调节与基底膜稳态相关的基因。这一假设是通过量化纹状体中缺氧相关基因和蛋白质的表达来评估的。通过测量毛细血管基底膜厚度、耳蜗电位和耳蜗氧张力来评估旨在逆转基底膜积累的药物操作。这些实验的结果为基底膜异常在听觉功能障碍中所起的作用提供了明确的描述。这项研究是在一只内耳毛细血管基底膜增厚的老鼠身上进行的。该小鼠作为基底膜异常的模型，因此所获得的数据将与其他具有毛细血管基底膜增厚和听力损失的疾病有关。

DESCRIPTION (provided by applicant): Specialized epithelial and supporting cells in the cochlea are closely associated with extracellular matrices. One such matrix, the basement membrane, utilizes type IV collagen to form a unique protein lattice to which other matrix proteins bind. During development, basement membranes play a critical role in cell migration and cell maturation, while in mature tissue they contribute to processes of cell adhesion, polarization and permeability. The role of basement membranes in the mature cochlea remains to be fully described. Nevertheless, animal models of diabetes mellitus, systemic lupus erythematosus, presbycusis, and Alport's syndrome exhibit abnormally thick strial capillary basement membranes and auditory dysfunction. The animal model of Alport's syndrome is of particular interest since it arises from a mutation in the gene encoding type IV collagen. The current proposal determines how thickened strial capillary basement membranes contribute to abnormal auditory function. The relationship between abnormal basement membranes and hearing loss is explored by determining the consequences of basement membrane accumulation on peripheral auditory function; evaluating hypoxia-related responses to basement membrane accumulation; and amelioration of hypoxia and auditory dysfunction by inhibition of strial capillary basement membrane accumulation. Experiments are proposed to test the validity of two hypotheses: 1) The abnormal basement membranes in strial tissue result in a deterioration of metabolic homeostasis in the cochlea that degrades cochlear function. This hypothesis is tested by depleting strial energy reserves with intense, but non-damaging, sound stimulation. Following exposure, aspects of peripheral auditory function as well as the electrochemical and ion transport properties of the stria vascularis are measured to determine changes in the homeostasis of the stria and scala media. 2) The accumulation of basement membrane proteins upregulate hypoxia-related responses that modulate genes associated with basement membrane homeostasis. This hypothesis is evaluated by quantifying the expression of hypoxia-related genes and proteins in the stria. Pharmacological manipulations designed to reverse basement membrane accumulation are evaluated by measuring strial capillary basement membrane thickness, the endocochlear potential, and cochlear oxygen tension. The results of these experiments provide a definitive picture of the role that abnormal basement membranes play in auditory dysfunction Narrative: This project evaluates the role of basement membranes in the inner ear. The research is performed in a mouse whose inner ear has thickened strial capillary basement membranes. The mouse serves as a model of basement membrane abnormality and therefore data obtained will be relevant to other disease conditions which have thickened strial capillary basement membranes and hearing loss.