MODELS OF INNER EAR MORPHOGENESIS

脊椎动物内耳是一个结构复杂的器官，由充满液体的导管和从中央前庭突出的环状管道组成。先天性内耳形态发生缺陷可导致耳聋和平衡障碍。这一建议旨在通过探讨耳囊形态发生的分子遗传学基础来洞察先天性耳畸形的起源。我们的假设是，基因表达结构域将脊椎动物耳囊细分为在边界上相互作用的隔室，以确定细胞命运和模式形成。我们将通过离子导入注射荧光示踪染料来绘制雏鸟和小鼠耳杯的命运图。命运图将提供有关细胞运动的基本机制信息，这些运动负责将耳杯转化为卵圆形上皮囊泡。这一信息将填补耳朵发育领域的一个关键空白，因为目前尚不清楚胎盘阶段的基因表达模式如何与囊泡期或更高阶段的基因表达模式相关。此外，命运图谱将为逆转录病毒介导的基因转移提供基因局部错误表达的蓝图。我们的想法是，如果在新生的耳囊中需要精确的基因表达边界来构建内耳模式，那么在时间或空间上不合适的基因表达焦点的创建可能会以一种可预测的方式扰乱形态发生。这一建议的一个必然目标是建立一个小鼠全胚胎培养模型，用于研究早期耳聋个体发育。通过实验获得不断扩大的自然和诱导突变小鼠名单，可能会进一步加深我们对内耳形态发生的遗传机制的理解，并为消除先天性耳聋和平衡障碍提供基础。

The vertebrate inner ear is a structurally complex organ consisting of fluid-filled ducts and toroidal canals protruding from a central vestibule. Congenital defects of inner ear morphogenesis can lead to deafness and balance disorders. This proposal aims to gain insight into the origins of congenital ear malformations by probing the molecular-genetic basis of otic vesicle morphogenesis. Our hypothesis is that gene expression domains subdivide the vertebrate otocyst into compartments that interact at boundaries to specify cell fate and pattern formation. We will fate map the chick and mouse otic cup by iontophoretic injection of fluorescent tracer dye. The fate maps will provide essential mechanistic information regarding the cellular movements responsible for conversion of the otic cup to an ovoid epithelial vesicle. This information will fill a critical void in the ear development field as it is not currently known how gene expression patterns at the placode stage correlate with those at the vesicle stage or beyond. In addition, the fate maps will provide a blueprint for the focal misexpression of a gene by retrovirus-mediated gene transfer. Our idea is that if precise boundaries of gene expression in the nascent otocyst are required for patterning the inner ear, then creation of temporally or spatially inappropriate foci of gene expression will likely perturb morphogenesis in a predictable way. A corollary goal of this proposal is to establish a mouse whole embryo culture model for studying early otic ontogeny. Experimental access to the ever-expanding list of natural and induced mutant mice would likely further our understanding of the genetic mechanisms that underlie inner ear morphogenesis and provide a basis for eliminating congenital deafness and balance disorders.