BRN-3 POU DOMAIN PROTEINS IN RETINA DEVELOPMENT

描述（改编自申请人摘要）：该提案涉及 随着了解视网膜神经节细胞如何在视网膜中指定， 脊椎动物视网膜 虽然视网膜发育的模式一直是 虽然描述得很好，但对控制这种疾病的分子事件知之甚少。 视网膜神经元的排列、定型和分化。 一 理解视网膜发育的方法是定义特定的 重要的基因调控事件的组成部分。 该提案的重点是 三个密切相关的POU结构域基因brn-3a、brn-3b和brn-3c， 与神经元发育过程中的细胞命运特化有关。 这些基因在小鼠视网膜中表达， 神经节细胞，也在背根和三叉神经节， 大脑的特定区域。 定向破坏表明brn-3b 是视网膜神经节细胞发育所必需的 而brn-3a和brn-3c对于躯体感觉的发育是必需的， 和听觉神经元。 最初的实验导致了 假设Brn-3b是决策过程的一部分， 控制有丝分裂后的神经母细胞是否接受神经节细胞 命运 为更准确地确定其作用，提出了三个具体目标 Brn-3b在视网膜神经节细胞发育中的作用及其相互关系 Brn-3a和Brn-3c：（1）Brn-3b表达细胞在 将在野生型和Brn-3b缺陷型中测定视网膜发育 使用插入brn-3b基因座的brn-3b（-/-）lacZ基因作为标记的胚胎 Brn-3a、Brn-3b的功能等效性 视网膜中Brn-3a和Brn-3c的同源重组将被测试 和brn-3c序列进入brn-3b基因座的能力;和（3）Brn-3b的能力， 将未定型的视网膜神经母细胞转化为神经节细胞， 通过在发育中的Brn-3b的异位逆转录病毒表达来评估 鸡胚的视网膜。

DESCRIPTION (Adapted from applicant's abstract): The proposal is concerned with understanding how retinal ganglion cells are specified in the vertebrate retina. Although the pattern of retinal development has been well described, very little is known about the molecular events that control the arrangement, commitment, and differentiation of retinal neurons. One approach to understanding retinal development is to define specific components of essential genetic regulatory events. This proposal focuses on three closely related POU-domain genes, brn-3a, brn-3b, and brn-3c, which have been implicated in cell fate specification during neuronal development. These genes are expressed in the murine retina specifically within subsets of ganglion cells and also in dorsal root and trigeminal ganglia, and in selected regions of the brain. Targeted disruptions have shown that brn-3b is required for the development of a large set of retinal ganglion cells whereas brn-3a and brn-3c are essential for the development of somatosensory and auditory neurons, respectively. Initial experiments have led to the hypothesis that Brn-3b is part of a decision-making process that acts to control whether or not a post-mitotic neuroblast adopts a ganglion cell fate. Three specific aims are proposed to determine more precisely the role that Brn-3b plays in retinal ganglion cell development and its relationship to Brn-3a and Brn-3c: (1) the fate of brn-3b-expressing cells during retinal development will be determined in wild type and brn-3b-deficient embryos using a brn-3b(-/-)lacZ gene inserted into brn-3b locus as a marker for brn-3b positive cells; (2) the functional equivalence of Brn-3a, Brn-3b and Brn-3c in retina will be tested by homologous recombination of brn-3a and brn-3c sequences into brn-3b locus; and (3) the ability of Brn-3b to convert uncommitted retinal neuroblasts to a ganglion cell fate will be assessed by ectopic retroviral expression of brn-3b in the developing retinas of chick embryos.