GENETIC ANALYSIS OF RETINAL DEGENERATION

特定的遗传缺陷导致了很大比例的 折磨人类的视网膜疾病。的长期目标 这项研究计划是为了描述类似的遗传基因 无脊椎动物果蝇的视网膜变性综合征 更好地了解退行性视网膜疾病的分子基础。 在之前的资助期间，我们确定了四个分子基础 果蝇的遗传性视网膜变性综合征。这项建议 关注的是其中一个基因突变的细胞机制 视紫红质基因会导致视网膜疾病。视紫红质突变是已知的 导致人类、其他脊椎动物和 果蝇。在大多数已知的情况下，包括果蝇突变体 将研究发现，突变的视紫红质以显性方式触发 退化。此外，果蝇突变体与 大多数人类突变基因，它们似乎破坏了 翻译后成熟途径。这里提出的实验将 研究细胞机制和额外的基因产物 参与视紫红质的成熟和循环。这个项目是有组织的 具体到四个目标： (1)研究某些果蝇视紫红质的支配性质 变种人。我们将使用组织学标记来检查 突变蛋白在光感受器中的作用，决定突变的效果 其他膜蛋白上的视紫红质，并开发一种基因筛查 视紫红质成熟所需的其他基因 (2)鉴定与视紫红质有关的其他分子成分 成熟。膜蛋白成熟所需的基因产物 通过内质网/高尔基复合体和高尔基体后 视紫红质的运输将被描述。我们将分析机制 参与视紫红质向光敏膜的运输和 视网膜变性B蛋白向特化内质的转运 光感受器的网状膜。 (3)分析该酶的酶调节和底物特异性。 视网膜变性C(RdgC)基因。视紫红质被认为是一种 RdgC磷酸酶的底物。我们将对酶的特性进行表征 RdgC蛋白的活性及其突变体分析 改变了监管。 (4)鉴定视紫红质成熟所需的两种基因产物 已经通过突变进行了鉴定。这些基因需要生成 高水平的视紫红质，可能是通过促进有效利用 我们将确定这些基因是否编码起作用的蛋白质 在光感受器中，如果是这样的话，确定 编码的基因。

Specific genetic defects are responsible for a large percentage of the retinal diseases that afflict human populations. The long range goal of this research program is to characterize analogous genetically inherited retinal degeneration syndromes in the invertebrate, Drosophila, to better understand the molecular basis of degenerative retinal diseases. During previous grant periods, we determined the molecular basis of four inherited retinal degeneration syndromes in Drosophila. This proposal is focused on the cellular mechanisms by which mutations in one of these genes, rhodopsin, causes retinal disease. Rhodopsin mutations are known to cause retinal degeneration in humans, other vertebrates, and in Drosophila. In most known cases, including the Drosophila mutants we will study, the mutant rhodopsin acts in a dominant fashion to trigger degeneration. Also, the Drosophila mutants share the property with the majority of human mutant genes that they appear to disrupt the posttranslational maturation pathway. The experiments proposed here will investigate the cellular mechanisms and additional gene products involved in rhodopsin maturation and recycling. The project is organized into four specific aims: (1) To examine the dominant nature of certain Drosophila rhodopsin mutants. We will use histological markers to examine the fate of the mutant protein in photoreceptors, determine the effect of the mutant rhodopsin on other membrane proteins, and develop a genetic screen for additional genes required for rhodopsin maturation (2) To identify additional molecular components involved in rhodopsin maturation. Gene products required for membrane protein maturation through the endoplasmic reticulum/Golgi complex and for post-Golgi transport of rhodopsin will be characterized. We will analyze mechanisms involved in rhodopsin transport to the photosensitive membranes and retinal degeneration B protein transport to the specialized endoplasmic reticulum membranes of the photoreceptor. (3) To analyze the enzymatic regulation and substrate specificity of the retinal degeneration C (rdgC) gene. Rhodopsin is thought to be a substrate of the rdgC phosphatase. We will characterize the enzymatic activity of the rdgC protein and analyze mutants of rdgC exhibiting altered regulation. (4) To characterize two gene products required rhodopsin maturation already identified by mutation. These genes are required to generate high levels of rhodopsin, probably by promoting efficient utilization of vitamin A. We will determine if these ones encode proteins that act in photoreceptors, and if so, determine the molecular nature of the encoded gene.