DEVELOPMENT STUDIES OF THE INNER EAR

听觉是人类交流能力的基础， 在儿童习得语言时尤为重要。 的 内耳的感觉感受器细胞起着关键作用：它们的缺失 由于出生缺陷（先天性耳聋），或在生命后期丧失， 导致完全失聪 为了防治先天性耳聋， 在人类交流中造成的缺陷，有必要了解 内耳的正常发育。 随着耳朵的发育， 必须经历一系列关键的决定， 细胞类型变成（即，命运的决定），什么空间 它们必须与相邻细胞进行安排，以产生 适当的三维结构（即，图案形成）。 的 该项目的具体目标是（1）描述细胞命运的种类 脊椎动物内耳中的单个祖细胞做出的决定 通过谱系分析和（2）测试一个候选分子的作用 在细胞命运决定和/或模式形成中。 的方法 实现这两个具体目标主要涉及使用逆转录病毒 载体作为一种高效的基因转移技术， 进入鸡的内耳 对于特定目标1（谱系 分析），复制缺陷型逆转录病毒载体将用于 递送编码碱性磷酸酶或β- 将半乳糖苷酶转移到单个祖细胞上作为标记它们的方式， 他们所有的后代。 克隆分析将在以下阶段进行： 区域和细胞类型的区别是显而易见的。 为特定 目的2（基因扰动），复制能力的逆转录病毒载体， 将使用编码各种形式的含同源框的基因SOHo-1 在内耳祖细胞中错误表达这种蛋白质。 SOHO-1是 提出在细胞命运决定中发挥作用， 根据对mRNA的初步描述， 表达模式 本研究的目的是进一步明确 SOHo-1的正常表达模式，并改变该表达模式 在耳朵形成的关键阶段。 形成的变化 作为SOHo-1错误表达结果的穗表明该基因 确实在建立正常的解剖结构中起着重要的作用， 耳朵 在基因微扰的过程中建立的基因微扰方法 这项研究可以在未来用于测试许多其他候选基因。 在耳朵发育中的作用。 从基因中获得的表型 扰动实验可以模拟，并且在某些情况下与， 人类先天性内耳畸形。

The sense of hearing is fundamental to man's ability to communicate, and is particularly important in children as they acquire language. The sensory receptor cells of the inner ear play a pivotal role: their absence due to birth defects (congenital deafness), or their loss later in life, results in total deafness. To combat congenital deafness and the resulting deficits in human communication, it is necessary to understand the normal development of the inner ear. As the ear develops, the cells that comprise the ear must undergo a series of key decisions as to what cell type(s) to become (i.e., fate determination), and what spatial arrangements they must make with neighboring cells to generate the appropriate three-dimensional structure (i.e., pattern formation). The specific aims of this project are (1) to describe the kinds of cell fate decisions made by individual progenitor cells in the vertebrate inner ear through lineage analysis and (2) to test one candidate molecule for a role in cell fate determination and/or pattern formation. The methods for accomplishing these two specific aims primarily involve using retrovirus vectors as a highly efficient gene transfer technique to introduce genes into the developing inner ear of the chicken. For Specific Aim 1 (lineage analysis), replication-defective retrovirus vectors will be used to deliver a marker gene encoding either alkaline phosphatase or beta- galactosidase to individual progenitor cells as a way of labeling them and all of their progeny. Clonal analysis will be performed at a stage when regional and cell type distinctions are readily apparent. For Specific Aim 2 (gene perturbation), replication-competent retrovirus vectors that encode various forms of a homeobox-containing gene, SOHo-1, will be used to misexpress this protein in inner ear progenitor cells. SOHo-1 is proposed to play a role in the cell fate decision involving whether or not to become a sensory organ based on preliminary descriptions of its mRNA expression pattern. The purpose of this study is to further define the normal expression pattern of SOHo-1, and to alter this expression pattern during critical stages of ear formation. Alterations in the formation of the ear as a result of SOHo-1 misexpression would indicate that this gene does indeed play a functional role in establishing the normal anatomy of the ear. The gene perturbation methods established during the course of this study can be used in the future to test many other candidate genes for a role in ear development. The phenotypes obtained from gene perturbation experiments may mimic, and in some cases correlate with, human congenital malformations of the inner ear.