Factors Regulating Inner Ear Specification

调节内耳规格的因素

• 批准号: 7032780
• 负责人: Jean-Pierre Saint-Jeannet
• 金额: $ 26.95万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-12-14 至 2010-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7032780
• 关键词: DNA binding protein; Wnt gene /protein; Xenopus; antisense nucleic acid; biological signal transduction; developmental genetics; embryogenesis; gene expression; genetic regulation; histology; labyrinth; nonmammalian vertebrate embryology; nucleoproteins; oligonucleotides; protein protein interaction; protein quantitation /detection; transcription factor; yeast two hybrid system

DESCRIPTION (provided by applicant): The vertebrate inner ear is a sensory organ implicated in hearing, balance and detection of acceleration. It develops from a thickening of the embryonic ectoderm known as the otic placode. Defining the molecular processes leading to specification of the otic placode is essential to understand inner ear development. Sox proteins comprise a large class of transcriptional regulators. One member of this family, Sox9, a well- established regulator of chondrogenesis and sex determination, is also one of the earliest genes expressed in the presumptive otic placode. Mutations in Sox9 result in campomelic dysplasia (CD), a fatal human disorder characterized by severe skeletal malformations and XY sex reversal. Reports of rare CD patients that survived indicate that they are also affected with sensorineural deafness, suggesting that Sox9 may play an important role in the development of the auditory system. We have shown that the otic expression of Sox9 in Xenopus is initiated early in the sensory layer of the ectoderm. In this tissue, Sox9 expression is regulated by Fgf and Wnt signaling and co-localizes with Pax8, one of the earliest gene expressed in response to otic placode inducing signals. Depletion of Sox9 protein in whole embryos using morpholino antisense oligonucleotides causes a dramatic loss of early and late otic markers, and in the most extreme cases these embryos fail to form a morphologically recognizable otic vesicle. The experiments below will test the following hypothesis: the transcription factor Sox9 is a key component of regulatory pathway required for inner ear specification. We propose: 1-To define the molecular regulators of Sox9 expression in the otic placode by establishing the origin of the signals activating Sox9 expression in the otic placode; and defining the requirement and sufficiency of Fgf and Wnt signaling for otic placode specification in whole embryos and animal explants. 2-To characterize the ear phenotype of Xenopus Sox9-deficient embryos 3-To identify Sox9-interacting partner molecules in the otic placode using a yeast two-hybrid screen, since Sox proteins are known to regulate their target genes through interaction with cell type-specific partner molecules.The characterization of such partner molecules should further our understanding of Sox9-mediated gene regulation in the context of the developing inner ear.

描述(由申请人提供)： 脊椎动物的内耳是一个感觉器官，与听力、平衡和加速度检测有关。它是由被称为耳胎素的胚胎外胚层增厚而来的。确定导致耳道胎盘规范的分子过程对于了解内耳发育是至关重要的。SOX蛋白由一大类转录调控因子组成。Sox9是这个家族的成员之一，它是软骨形成和性别决定的成熟调节因子，也是在假定的胎盘中表达的最早的基因之一。Sox9的突变会导致驼核发育不良(CD)，这是一种致命的人类疾病，以严重的骨骼畸形和XY性反转为特征。罕见的CD患者存活的报道表明，他们也受到感觉神经性耳聋的影响，这表明Sox9可能在听觉系统的发育中发挥重要作用。我们已经证明，Sox9在非洲爪哇中的听觉表达是在外胚层的感觉层早期开始的。在这个组织中，Sox9的表达受成纤维细胞生长因子和Wnt信号的调节，并与Pax8共定位，Pax8是最早表达的响应胎盘诱导信号的基因之一。使用吗啉反义寡核苷酸耗尽整个胚胎中的Sox9蛋白会导致早期和晚期耳聋标记的急剧丧失，在最极端的情况下，这些胚胎无法形成形态上可识别的耳囊。下面的实验将验证以下假设：转录因子Sox9是内耳规范所需的调控途径的关键组成部分。我们建议：1-通过确定激活耳道胎盘Sox9表达的信号的来源，确定耳道胎盘中Sox9表达的分子调控；以及确定在整个胚胎和动物外植体中，成纤维细胞生长因子和Wnt信号对耳道胎盘规范的需求和充分性。2-鉴定非洲爪哇Sox9缺失胚胎的耳朵表型3-使用酵母双杂交筛选鉴定耳道胎盘中Sox9相互作用的伴侣分子，因为已知Sox蛋白通过与细胞类型特定的伴侣分子相互作用来调节其靶基因。这种伴侣分子的表征将有助于我们在内耳发育的背景下进一步理解Sox9介导的基因调控。