Signal Transduction Mechanisms in Ocular Albinism

描述(申请人提供)：眼白化病的信号转导机制 X连锁1型白化病患者表现为眼组织色素沉着减少，并出现一系列特征性特征，包括视力低下、眼球震颤、斜视、立体视降低和畏光。在解剖-细胞水平上，这些缺陷与中心凹发育不良、视杆感受器减少、视神经走线错误以及视网膜色素上皮中大黑素小体的异常发育有关。在分子水平上，这种表型是由于最近克隆的眼白化病1型基因(OA1)的突变所致。由视网膜色素上皮内的黑素小体表达，OA1氨基酸序列分析和结合研究表明，它是一个七跨膜G蛋白偶联受体。流行的假设是OA1中的分类或信号缺陷最终导致了白化病的表型。然而，关于OA1突变导致疾病的机制仍然存在重要的争议。该建议的具体目的是研究OA1/G蛋白在体外和体内的相互作用，确定用于黑素小体分选的OA1序列基序，并确定OA1的潜在黑素细胞配体。这些方法将涉及定点突变、对转基因细胞和转基因小鼠的表型分析，以及孤儿受体策略，即在高通量系统中将来自可能组织来源的经过生物化学纯化的配体应用于工程OA1配体传感器细胞。总之，这些研究将解决是否信号缺陷或蛋白质分类错误导致OA1表型，OA1如何靶向黑素体，以及OA1配体是什么。对这些问题的回答将促进我们对涉及视觉系统发育、信号转导和蛋白质分选的分子机制的理解。他们还可能提出新的治疗策略来治疗患有这种和其他基于视网膜色素上皮的视觉障碍的患者。在最近完成了加州大学欧文分校M.S.T.P.的医学博士学位后，我将进行这项研究，作为我在Jules Stein眼科研究所EyeSTAR(高级研究专业培训)项目培训的一部分。该计划结合了眼科临床住院医师和博士后基础科学研究培训，明确了培养眼科临床医生-科学家领袖的目标。在黛博拉·法伯博士的指导下，我希望开始学术生涯，并建立一个旨在了解和治疗视网膜疾病的研究实验室。

DESCRIPTION (provided by applicant): Signal Transduction Mechanisms in Ocular Albinism Patients with X-linked ocular albinism type 1 display decreased pigmentation of ocular tissues and suffer a characteristic series of traits that includes poor visual acuity, nystagmus, strabismus, reduced stereopsis, and photophobia. At an anatomic-cellular level, these deficits correlate with foveal hypoplasia, fewer rod photoreceptors, misrouting of the optic nerve, and the abnormal development of macromelanosomes in the retinal pigment epithelium. At a molecular level the phenotype is due to mutations in the recently cloned ocular albinism type 1 gene (OA1). Expressed by melanosomes within the retinal pigment epithelium, OA1 amino acid sequence analysis and binding studies suggest it is a seven-transmembrane G-protein coupled receptor. The prevailing hypothesis is that either a sorting or signaling defect in OA1 ultimately accounts for the albinism phenotype. However, important controversies concerning the mechanism by which a mutation in OA1 leads to disease remain. The specific aims of this proposal are to study the OA1/G-protein interaction in vitro and in vivo, to identify the OA1 sequence motif for melanosome sorting, and to identify potential melanocyte ligands for OA1. The methods will involve site-directed mutagenesis, phenotypic analysis of transfected cells and transgenic mice, and an orphan receptor strategy that applies biochemically purified ligands from likely tissue sources over an engineered OA1 ligand-sensor cell in a high-throughput system. Together, these studies will address whether a signaling defect or a protein sorting error accounts for the OA1 phenotype, how OA1 is targeted to melanosomes, and what is the OA1 ligand. Answers to such questions will advance our understanding of the molecular mechanisms involved in visual system development, signal transduction, and protein sorting. They may also suggest novel therapeutic strategies for treating patients suffering from this and other retinal pigment epithelium based visual impairments. Having recently completed my MD.-Ph.D. in the U.C. Irvine M.S.T.P., will conduct this research as part of my training in the EyeSTAR (Specialty Training in Advanced Research) program at the Jules Stein Eye Institute. This program integrates an Ophthalmology clinical residency and postdoctoral basic science research training with the expressed goal of developing clinician-scientist leaders in ophthalmology. Under the mentorship of Dr. Debora Farber, I hope to launch an academic career and establish a research laboratory aimed at understanding and treating retinal disease.