Factors Regulating Inner Ear Specification

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 发育自被称为耳胎素的胚胎外胚层的增厚。定义分子 导致耳道胎盘规范的过程对于了解内耳发育是必不可少的。 SOX蛋白由一大类转录调控因子组成。这个家庭的一位成员，索克斯9号，一口井- 已建立的软骨形成和性别决定的调节因子，也是最早表达的基因之一 假定的安慰剂。Sox9基因突变导致驼核发育不良(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患者的报告 存活表明他们也受到感觉神经性耳聋的影响，这表明Sox9可能发挥着一种 在听觉系统的发展中起着重要的作用。 我们已经证明，Sox9在非洲爪哇的听觉表达是在早期的感觉层开始的 外胚层。在该组织中，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。 最早对耳道胎盘诱导信号做出反应的基因之一。大豆中Sox9蛋白的耗竭 使用吗啡反义寡核苷酸的整个胚胎导致早期和晚期耳聋的戏剧性损失 标记，在最极端的情况下，这些胚胎无法形成形态上可识别的耳轮 水泡。下面的实验将检验以下假设：转录因子Sox9是一个关键 内耳规范所需的调节通路的组成部分。 我们建议：1-通过建立耳部胎盘中Sox9表达的分子调控机制来确定Sox9表达的分子调控。 外耳胎盘中激活Sox9表达的信号的来源；并定义需求和 成纤维细胞生长因子和Wnt信号在整个胚胎和动物外植体中对耳道胎盘规范的充分性。 2-鉴定Xenopus Sox9缺陷型胚胎的穗部表型3-鉴定Sox9-互作 使用酵母双杂交筛选耳道胎盘中的配对分子，因为SOX蛋白已知 通过与细胞类型特定的伙伴分子相互作用来调节它们的靶基因。 这种伙伴分子的存在应该会进一步加深我们对Sox9介导的基因调控的理解 发育中的内耳。

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 Xenpopus 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.