A role for diaphanous homolog 3 in the auditory system

描述（由申请人提供）：听力障碍占美国感觉缺陷障碍的大部分，每2000个新生儿中就有1个受到听力障碍的影响。虽然已知存在100多个耳聋基因位点，但只有不到一半的相关基因被确定。我们最近在透明同源基因3（人类为DIAPH3，小鼠为Diap3）的5'非翻译区发现了一个突变，该突变可导致转录增加和延迟性听神经病变（一种耳聋）。在另一种形式的耳聋中，也有一种与DIAPH3的同源物，但与肌动蛋白和微管相互作用的与隔膜相关的形成蛋白在听觉系统中的确切作用尚未阐明。我们已经开发了Diap3过表达的小鼠模型来解决这个悬而未决的问题。这里的长期目标是了解哺乳动物听觉系统中重要的蛋白质和分子途径的相互作用，以及该系统中的缺陷如何导致听力损失和/或耳聋。本应用程序的总体目标是研究Diap3的发育表达，表征一种新的小鼠耳聋模型，并研究这种听神经病变的分子机制。本研究的中心假设是Diap3在小鼠中的过表达将忠实地模拟人类听觉神经病变的机制，并有助于阐明听力损失的机制，我们假设听力损失是由于肌动蛋白失调造成的。提出这项研究的基本原理是我们发现人类中膜片3的上调会导致听神经病变。我们将通过两个具体目标来验证中心假设：1)确定Diap3在野生型小鼠中的表达谱，并确定我们新开发的转基因小鼠中的过表达程度；2)利用经典的听力测量方法以及研究耳蜗中肌动蛋白异构体的差异表达，确定Diap3过表达对转基因小鼠听觉系统的影响程度。完成这些目标将产生以下预期结果。首先，我们将清楚地了解Diap3在野生型小鼠中的表达谱。其次，我们将对小鼠模型进行表征，这将为研究人员提供一种测试疗法和检查Diap3蛋白下游效应物的新工具。第三，我们将了解Diap3过表达如何导致影响听觉系统的细胞骨架变化。

DESCRIPTION (provided by applicant): Hearing disorders account for the majority of sensory deficit disorders in the United States and affect 1 in 2000 births. Although more than 100 deafness loci are known to exist, fewer than half of the responsible genes have been identified. We have recently identified a mutation in the 5' untranslated region of the diaphanous homolog 3 gene (DIAPH3 in humans, Diap3 in mouse) that leads to increased transcription and delayed onset auditory neuropathy, a form of deafness. A homolog of DIAPH3 has been implicated in another form of deafness as well, but exact roles in the auditory system for the diaphanous-related formins, which interact with actin and microtubules, have not yet been elucidated. We have developed a mouse model of Diap3 overexpression to address this open question. The long-term goal here is to understand the interactions of proteins and molecular pathways important in the mammalian auditory system and how defects in this system lead to hearing loss and/or deafness. The overall objectives of this application are to investigate the developmental expression of Diap3, to characterize a new mouse model of deafness, and to investigate the molecular mechanism responsible for this form of auditory neuropathy. The central hypothesis for the proposed research is that Diap3 overexpression in mice will faithfully model the mechanism of human auditory neuropathy and help elucidate the mechanism of hearing loss, which we postulate is due to actin dysregulation. The rationale for the proposed research is our finding that upregulated DIAPH3 in humans' leads to auditory neuropathy. The central hypothesis will be tested by pursuing two specific aims: 1) Determine the expression profile of Diap3 in wild-type mice and determine the extent of overexpression in our newly developed transgenic mice; and 2) Determine the extent to which Diap3 overexpression affects the auditory system in transgenic mice using classical measures of hearing as well as by investigating differential actin isoform expression in the cochlea. Completion of these aims will provide the following expected outcomes. First, we will have a clear picture of the expression profile of Diap3 in wild-type mice. Second, we will have characterized mouse models that will provide researchers with a new tool for testing therapies and for examining downstream effectors of Diap3 protein. Third, we will gain understanding of how Diap3 overexpression may lead to cytoskeletal changes that impact the auditory system. PUBLIC HEALTH RELEVANCE: We have identified a gene, DIAPH3, that when overexpressed causes deafness. By elucidating its role in mice, we expect to help clarify an as yet unknown mechanism involved in the process of normal hearing. This new mouse model will be an important tool for testing potential therapies and will allow us to attain our ultimate goal of greater understanding of this form of deafness.