Genetically testing mechanisms of ocular development and disease

描述（由申请人提供）：IV型胶原α 1基因（Col4a1）突变可导致小鼠眼前节发育不全（ASD）和眼内压升高。最近，在一个ASD、高眼压症和青少年青光眼的家系中发现了COL4A1突变，但COL4A1尚未被广泛认为是ASD的候选基因。我们假设，COL4A1及其结合伴侣COL4A2的突变是ASD患者突变尚未确定的基础。在目标1中，我们将通过对ASD患者进行突变分析来直接测试我们的假设，这些患者已知在其他ASD致病基因中没有突变。此外，我们试图确定Col4a1突变导致ASD的位置和细胞机制。我们已经确定，COL4A1是普遍存在于眼基底膜在发展过程中，这使得从继发性病理确定原发性发病部位的任务复杂化。为了克服这一障碍，我们开发并验证了Col4a1的条件突变等位基因。在目标2中，我们将仅在发育中的透镜或仅在神经嵴起源的细胞中表达突变，以确定它们对ASD的相对贡献。最后，为了了解Col4a1突变如何导致眼发育不良并开始组装发育和致病途径，我们将鉴定ASD的遗传修饰剂。我们已经成功地绘制了一个能够强烈拯救ASD并允许突变小鼠具有几乎正常发育的眼睛的基因座。在目标3中，我们将对两种不同的遗传背景进行系统的大规模筛选，以确定额外的显性或隐性修饰位点和基因。了解遗传修饰剂如何拯救疾病可以为靶向治疗干预如何做到这一点提供有价值的见解。据我们所知，目前还没有其他研究小组评估COL4A1或COL4A2在眼部发育和疾病中的作用。本提案中概述的实验利用了宝贵和独特的资源，并将为正常眼部发育和致病途径的机制提供重要的新见解。 公共卫生相关性：本申请旨在鉴定导致早发性和侵袭性青光眼的眼发育不全的新遗传原因。该研究将使用独特的遗传工具来了解这些基因如何导致疾病，以及哪些细胞通路可能被新的治疗干预所靶向。

DESCRIPTION (provided by applicant): Mutations of the type IV collagen alpha 1 gene (Col4a1) can cause anterior segment dysgenesis (ASD) and elevated intraocular pressure in mice. Recently, a COL4A1 mutation was identified in a family with ASD, ocular hypertension and juvenile glaucoma, however, COL4A1, has not widely been considered a candidate gene for ASD. We hypothesize that mutations of COL4A1 and its binding partner COL4A2 underlie ASD in patients for whom mutations have not yet been identified. In Aim 1, we will test our hypothesis directly by performing mutational analysis on ASD patients that are known not to have mutations in other ASD-causing genes. Moreover, we seek to determine where, and by what cellular mechanism(s), Col4a1 mutation leads to ASD. We have determined that COL4A1 is ubiquitously present in ocular basement membranes during development, which complicates the task of determining sites of primary pathogenesis from secondary pathology. To overcome this obstacle we have developed and validated a conditional mutant allele of Col4a1. In Aim 2, we will express the mutation only in the developing lens or only in cells of neural crest origin to determine their relative contributions to ASD. Finally, to understand how Col4a1 mutations lead to ocular dysgenesis and to begin to assemble developmental and pathogenic pathways, we will identify genetic modifiers of ASD. We have already successfully mapped a locus that is able to strongly rescue ASD and permit mutant mice to have nearly normally developed eyes. In Aim 3, we will perform systematic large-scale screens of two distinct genetic backgrounds to identify additional dominant or recessive modifier loci and genes. Understanding how genetic modifiers rescue disease could provide valuable insight for how targeted therapeutic interventions might do the same. To our knowledge, no other group is currently evaluating the role of COL4A1 or COL4A2 in ocular development and disease. The experiments outlined in this proposal take advantage of valuable and unique resources and will provide important new insights into the mechanisms of normal ocular development and pathogenic pathways. PUBLIC HEALTH RELEVANCE: This application seeks to identify a novel genetic cause of ocular dysgenesis that leads to early onset and aggressive glaucoma. The study will use unique genetic tools to understand how these genes lead to disease and which cellular pathways might be targeted with novel therapeutic interventions.