PHOTORECEPTORS--EFFECTS OF DIFFERENTIATION FACTORS

虽然许多研究利用两栖动物、鸟类和哺乳动物组织 已经表明色素上皮（PE）是外部环境所必需的。 节膜生产的正常数量和结构，准确 发生这种情况的机制尚不清楚。PE可以服务于一个或多个服务器。 对下面的感光细胞提供更多的功能支持，即，的 适当的微环境，通过 或者是某些营养因子的来源， 调节基因表达。在本建议中，常设机构在以下方面的作用 光感受器分化和外节膜组织将 使用体外模型进行系统研究，在该模型中，视网膜将 在未分化的状态下进行培养。视网膜成熟， 在存在和不存在PE的情况下， 然而，膜在其不存在时是无序的。 因为 在没有PE的情况下，光感受器确实产生外节膜 可以利用该系统来确定哪些因素能够改变 膜的组织和蛋白质的合成 在其中视蛋白与视细胞间类视黄醇结合蛋白基因 表达和蛋白质合成以及外节组织 将在没有PE的情况下成熟的视网膜中进行比较和对比 vs.没有PE，但存在各种潜在的分化 包括乳糖、生长因子、类维生素A和IRBP。的PE 在发展过程中，无疑扮演着许多复杂的角色。 光感受器在测试时，任何一个组件都不太可能 单独将恢复一个完整的表达水平和综合的 感光细胞特异性分化标记物。 然而，系统 评估每个测试条件的能力，以提高 在对照水平以上的表达和合成提供了一种直接的方法， 确定PE可以提供的各种组件， 支持感光细胞分化。

While many investigations utilizing amphibian, avian and mammalian tissue have suggested that the pigment epithelium (PE) is necessary for outer segment membrane production of normal quantity and structure, the exact mechanism(s) by which this occurs is not known. The PE may serve one or more functional supports to the underlying photoreceptor cells, i.e.,the appropriate microenvironment, a structural template via the interphotoreceptor matrix or be the source of some trophic factor(s) that regulate gene expression. In this proposal, the role of the PE on photoreceptor differentiation and outer segment membrane organization will be systematically explored using an in vitro model in which retinas will be removed to culture in an undifferentiated state. The retinas mature and elaborate outer segments in both the presence and absence of the PE, however the membranes are disorganized in its absence. Because photoreceptors do produce outer segment membrane in the absence of the PE the system can be exploited to determine what factor(s) are able to alter the organization of the membranes and the synthesis of the proteins therein. Opsin and interphotoreceptor retinoid binding protein (IRBP) gene expression and protein synthesis as well as outer segment organization will be compared and contrasted in retinas allowed to mature without a PE vs. without a PE yet in the presence of various potential differentiation factors including lactose, growth factors, retinoids and IRBP. The PE undoubtedly plays a number of complex roles during the development of photoreceptors. It is unlikely that any one of the components when tested alone would restore a full level of expression and synthesis of the photoreceptor specific differentiation markers. However, a systematic assessment of the ability of each of the test conditions to enhance expression and synthesis above control levels offers a direct approach to identifying the various components that could be provided by the PE which support photoreceptor differentiation.