The Role of TULP1 in Photoreceptor Cells

描述(申请人提供)：TULP1是我们发现的导致常染色体隐性遗传性视网膜色素变性的基因，这是一种遗传性视网膜变性，导致全球近100万人失明。约50%的病例已知RP的遗传病因；然而，导致该病的生化途径要少得多。这些研究的总体目标是探索TULP1在视网膜中的生理功能，并确定与TULP1突变相关的导致光感受器退化的病理机制。Tulp家族由四种功能未知的蛋白质组成，其中两种与光感受器退化有关。 这项应用的两个特定目的是为了检验核心假设，即TULP1是涉及光感受器细胞中蛋白质定向移位的分子机制的组成部分。第一个特定的目的是确定TULP1在光感受器运输途径中的作用。这将通过使用免疫细胞化学来确定外节蛋白、细胞内运输蛋白和突触蛋白在tulp1/-视网膜中是否被错误定位来完成。免疫电子显微镜将被用来确定被错误运输的蛋白质是否是tulp1-/-视网膜细胞外小泡上的货物。第二个特定目的是确定光感受器细胞中TULP1/Dynamin-1相互作用的功能。这将通过确定TULP1和Dynamin-1之间相互作用的功能结构域，并确定导致RP的TULP1突变是否改变两种蛋白质之间的结合来完成。还提出了利用Cre-loxP突变产生光感受器细胞中缺乏Dynamin-1的表型小鼠的实验。这些小鼠的转运途径将按照目标1中的描述进行评估。 由于人们对Tulp蛋白知之甚少，发现有关Tulp蛋白功能的信息应该可以提供有关光感受器退化途径的知识。这项工作有可能成为未来旨在评估可能减缓、停止或逆转视网膜变性过程的治疗方式的研究的基础。

DESCRIPTION (provided by applicant): TULP1 is a gene we identified to cause autosomal recessive retinitis pigmentosa, a hereditary retinal degeneration blinding nearly 1 million people worldwide. The genetic etiology of RP is known for about 50% of cases; however, the biochemical pathways involved in causing the disease much less. The overall objectives of the proposed studies are to explore the physiologic function of TULP1 in the retina and to define the pathologic mechanism leading to photoreceptor degeneration associated with TULP1 mutations. The TULP family consists of four proteins of unknown function, two of which are linked to photoreceptor degeneration. The two specific aims of this application are designed to test the central hypothesis that TULP1 is a component of the molecular machinery involved in the directional translocation of proteins in photoreceptor cells. The first specific aim is to determine the role of TULP1 in photoreceptor transport pathways. This will be accomplished by using immunocytochemistry to determine whether outer segment proteins, intracellular transport proteins and synaptic proteins are mistargeted in tulp1-/- retinas. Immunoelectron microscopy will be performed to determine if the proteins that are incorrectly transported are cargo on the extracellular vesicles in tulp1-/- retinas. The second specific aim is to determine the function of the TULP1/Dynamin-1 interaction identified in photoreceptor cells. This will be done by identifying the functional domains that interact between TULP1 and Dynamin-1 and determining whether TULP1 mutations that cause RP alter the binding between the two proteins. Experiments are also proposed to generate and phenotype mice lacking Dynamin-1 in photoreceptor cells using Cre-loxP mutagenesis. Transport pathways will be evaluated in these mice as described in aim 1. Since little is known about TULP proteins, discovering information regarding the function of TULP proteins should provide knowledge about the pathways involved in photoreceptor degeneration. It is possible that this work could form the foundation for future studies aimed at evaluating therapeutic modalities that might slow, stop, or reverse the course of retinal degeneration.