Molecular Studies of Retinal Degeneration in Drosophila

描述(申请人提供)：我们的长期目标是揭开遗传性人类致盲疾病的分子遗传学，如视网膜色素变性(RP)和年龄相关性黄斑变性(AMD)。在AMD和RP中，导致感光细胞死亡的基因缺陷是高度异质性的，现在包括超过132个基因的列表。AMD和RP复杂多样的临床和遗传学表现表明，这些疾病有多种亚型，每种亚型都有不同的遗传和生化基础。这种复杂性，罕见的RP和AMD患者的眼组织，以及广泛的果蝇遗传学知识基础，这些都使果蝇成为研究遗传性视网膜变性疾病的强大动物模型。我们建议使用果蝇作为一个模型来识别和描述人类致盲疾病中的新基因座，为视网膜退化的分子基础提供机械性的见解。我们将使用遗传、生化、细胞生物学、电生理和分子方法的综合策略来揭示光感受器细胞中协调蛋白质生物合成的不同分子信号机制。我们的研究重点是确保新合成蛋白质正确折叠、修饰、寡聚组装、质量控制、运输和靶向的那些事件。这些过程中的缺陷通常会刺激广泛的细胞反应，从而导致发病，在严重的情况下，还会导致神经退化。在这里，我们将描述分子伴侣calnexin，以及在calnexin途径中起作用的4个新的基因座：cip1、cip2、cip3和cip4。Calnexin是一种分子伴侣，能促进内质网(ER)中新生糖蛋白的正确折叠。一旦离开内质网，新折叠的蛋白质必须被运送到高尔基体，在那里它们经历一系列新的修饰。蛋白质在两个隔室之间的运输是通过小泡的萌发和融合进行的。我们将描述一种新的光感受器SNARE蛋白，它是高尔基体囊泡融合所必需的。我们已经证明，Calnexin、cip1-4和SNARE基因的突变会导致视紫红质表达缺陷，并导致视网膜退化。我们的发现将被用于筛选人类AMD和RP家系中类似的突变。我们的目标是发现致盲疾病中的新基因，为视网膜变性的分子机制提供见解，并为治疗RP和AMD提供治疗方法。

DESCRIPTION (provided by applicant): Our long-term objective is to unravel the molecular genetics of hereditary human blinding diseases, such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Genetic defects that lead to photoreceptor cell death in AMD and RP are highly heterogeneous and now include a list of more than 132 genes. The complex and various clinical and genetic findings in AMD and RP suggest that there are multiple subtypes of the diseases, each with a distinct genetic and biochemical basis. This complexity, the infrequent availability of ocular tissues from RP and AMD patients, and the broad base of knowledge of Drosophila genetics, all combine to make Drosophila a powerful animal model for studying inherited retinal degeneration disorders. We propose to use Drosophila as a model to identify and characterize novel loci in human blinding diseases, providing mechanistic insights into the molecular basis of retinal degeneration. We will use an integrated strategy of genetic, biochemical, cell biological, electrophysiological, and molecular approaches to uncover the diverse molecular signaling mechanisms that coordinate protein biosynthesis in photoreceptor cells. Our research focuses on those events that ensure correct folding, modification, oligomeric assembly, quality control, trafficking and targeting of newly synthesized proteins. Defects in these processes often stimulate extensive cellular responses that lead to pathogenesis and, in severe cases, neurodegeneration. Here, we will characterize the molecular chaperone calnexin, and 4 novel loci that function in the calnexin pathway: cip1, cip2, cip3 and cip4. Calnexin is a molecular chaperone that promotes the proper folding of nascent glycoproteins in the endoplasmic reticulum (ER). Upon exiting the ER, newly folded proteins must be transported to the Golgi where they undergo a new set of modifications. Transport of proteins between the two compartments occurs via the budding and fusion of vesicles. We will characterize a novel photoreceptor SNARE protein required for vesicular fusion events in the Golgi. We have shown that mutations in calnexin, cip1-4 and the snare gene cause defects in rhodopsin expression and lead to retinal degeneration. Our findings will be used to screen human AMD and RP pedigrees for similar mutations. We aim to uncover novel loci in blinding diseases, provide insights into the molecular mechanisms of retinal degeneration, and offer therapeutic approaches for treating RP and AMD.