Cellular and Molecular Mechanisms Regulating Photoreceptor Morphology

描述(申请人提供)：光感受器是对光作出反应并将其转化为化学信号的初级细胞，也是光感受器变性疾病中受影响的细胞，包括黄斑变性、视网膜色素变性(RP)和其他遗传性视网膜变性。虽然许多基因的突变与感光器退行性疾病有关，但我们仍然对这些突变导致感光器死亡的原因知之甚少。这一建议旨在扩大我们对脊椎动物光感受器如何获得和保持其独特的功能形态以及光感受器形态与生存之间关系的理解。我们已经证明含有FERM结构域的蛋白嵌合眼(MOE)是Crumbs蛋白功能的重要调节因子，直接与Crumbs蛋白相互作用，并表明缺乏MOE功能的杆状光感受器有比正常更大的外节。据我所知，这是第一个基因功能丧失的例子，导致外部片段比正常大，而不是更小。人类面包屑同源基因1(CRB1)的突变与两种失明疾病有关，Leber先天性黑色素症和视网膜色素变性12。这些疾病的严重性和早期发病表明CRB1功能在光感受器发育的早期阶段至关重要，并表明了解CRB1及其相关蛋白在光感受器中的作用可能有助于我们深入了解治疗LCA和Rp12的方法。缺乏Crb1功能的小鼠的光感受器比正常的内节和外节短。测定光感受器中面包屑蛋白的功能也可能进一步深入了解光感受器发育的早期阶段。为了进一步了解光感受器形态发生的细胞和分子机制，我们提出了三个具体目标：(1)研究Crb2a在调节光感受器和Muller胶质细胞形态中的作用。(2)检测PrkCi在调节Crumbs蛋白功能、光感受器和Muller胶质细胞形态中的作用。(3)研究与MoE/Epb4115相互作用的亲红细胞素1(Rhpn1)在调节Crumbs蛋白功能中的作用。我们研究的另一个长期目标是开发工具来测试外节和内节大小与感光器退化之间的因果关系，因为内节和外节的缩短通常在感光器退化之前观察到。 与公共健康相关：这项建议旨在扩大我们对脊椎动物光感受器如何获得和保持其独特的功能形态的理解。光感受器退化是大多数形式的视力丧失的原因，但我们对这些细胞为什么或如何死亡知之甚少。我们的研究旨在延长光感受器在疾病过程中的存活和功能。

DESCRIPTION (provided by applicant): Photoreceptors are the primary cells that respond to light and transduce it into a chemical signal and are the cells affected in photoreceptor degeneration diseases, including macular degeneration, retinitis pigmentosa (RP) and other inherited retinal degenerations. Although mutations in many genes have been identified that are associated with photoreceptor degeneration diseases, we still know very little about why these mutations cause photoreceptors to die. This proposal seeks to expand our understanding of how vertebrate photoreceptors attain and maintain their unique functional morphology and relationship between photoreceptor morphology and survival. We have shown that the FERM domain containing protein Mosaic eyes (Moe) is an important regulator of Crumbs protein function, directly interacts with Crumbs proteins and also showed that rod photoreceptors that lack moe function have outer segments that are larger than normal. To my knowledge this is the first example of loss-of-function of a gene that results in a larger than normal outer segment instead of a smaller one. Mutations in the human CRUMBS HOMOLOGUE 1 (CRB1) are associated with two vision-loss diseases, Leber's congenital amaurosis and retinitis pigmentosa 12. The severity and early onset of these diseases suggest that CRB1 function is critical for early stages of photoreceptor development and suggest that understanding the role of CRB1 and related proteins in photoreceptors may give us insight into ways to treat LCA and RP12. Photoreceptors in mice lacking Crb1 function have shorter than normal inner and outer segments. Determining the function of the Crumbs proteins in photoreceptors may also provide further insight into the early stages of photoreceptor development. To further our understanding of the cellular and molecular mechanisms that underlie photoreceptor morphogenesis we propose three specific aims: (1) Examine the role of Crb2a in regulating photoreceptor and Muller glial morphology. (2) Examine the role of Prkci in regulating Crumbs protein function and photoreceptor and Muller glial morphology. (3) Examine the role of Rhophilin 1 (Rhpn1), a protein that interacts with Moe/Epb41l5, in regulating Crumbs protein function. An additional long-term goal of our studies is to generate tools to test the causal relationship between outer and inner segment size and photoreceptor degeneration because a shortening of inner and outer segments is often observed prior to photoreceptor degeneration. PUBLIC HEALTH RELEVANCE: This proposal seeks to expand our understanding of how vertebrate photoreceptors attain and maintain their unique functional morphology. Photoreceptor degeneration is the cause of most forms of vision loss and yet we understand very little about why or how these cells die. Our research is aimed towards prolonging the survival and function of photoreceptors during disease processes.