Genetic modifiers of Cep290-mediated retinal degeneration

摘要 Leber先天性黑蒙（LCA）是一组遗传性视网膜变性疾病，其特征在于： 眼球震颤和失明，通常在生命的第一年表现出来。与几种视网膜变性 在某些疾病中，许多形式的LCA涉及光感受器纤毛的功能障碍。CEP 290基因的突变是 LCA的最常见原因，暗示CEP 290是该疾病的主要贡献者。CEP 290编码一个 一种大的蛋白质，被认为是调节蛋白质运输通过连接纤毛的光感受器跨越 内节和外节。使用CEP 290介导的LCA的小鼠模型，rd 16小鼠，我们发现 小鼠中Cep 290表型的相对严重性对遗传背景高度敏感。这里我们 我建议用老鼠做实验，利用这种背景敏感性来识别遗传修饰剂 Cep 290介导的视网膜变性。这些修饰剂的鉴定既有基础的，也有临床的， 意义从基础生物学的角度来看，对遗传修饰剂的研究可以揭示基本的生物学特性， CEP 290，感光纤毛的功能，以及它们在生理性视网膜疾病中的完形作用 上下文从临床的角度来看，遗传修饰剂的鉴定提供了一个机会， 治疗替代品我们当前提案的前提、可行性以及我们有能力 进行视网膜变性的定量修饰剂研究，所有这些研究都源于最近一个相对较大的机构， 工作我们用小鼠进行了大规模的遗传杂交，并确定了修饰视网膜色素的数量性状基因座。 Cep 290 rd 16突变纯合子小鼠的疾病严重程度。在被鉴定为 特别重要的是，我们目前的建议集中在视网膜变性数量性状的修饰因子上， 基因座1（Mrdq 1）位于小鼠12号染色体上。这种修饰剂的一个独特功能帮助我们 确定其分子基础的一个重要原因是，它显示了印记--其影响根据起源的父母而变化。 使用物理映射结合视网膜表达基因的研究，我们有 在一种以前未研究过的微小RNA中发现了一种明显的突变，这种突变极有可能是致病原因。 突变该提案的实验描述了严格确认我们已经确定了 Mrdq 1修饰物（特异性目标1）的精确突变，并开始研究其作用机制 通过识别存在于感光细胞中的microRNA的下游靶标。完成后，我们 我希望这项工作对CEP 290介导的LCA产生影响，并促进更好地了解如何 两种未充分研究的现象，通过microRNA和印记的基因调节，影响视网膜疾病。

Abstract Leber congenital amaurosis (LCA) is a group of inherited retinal degenerative diseases characterized by nystagmus and blindness that typically manifest in the first year of life. As with several retinal degenerative diseases, many forms of LCA involve dysfunction of photoreceptor cilia. Mutations in the CEP290 gene are the most common cause of LCA, implicating CEP290 as a major contributor to the disease. CEP290 encodes a large protein proposed to regulate protein transport through the photoreceptor connecting cilium spanning the inner and outer segments. Using a mouse model of CEP290-mediated LCA, the rd16 mouse, we have found that the relative severity of Cep290 phenotypes in mice is highly sensitive to genetic background. Here, we propose experiments using mice that take advantage of this background sensitivity to identify genetic modifiers of Cep290-mediated retinal degeneration. Identification of these modifiers has both basic, and clinical, significance. From a basic biology perspective, studies of genetic modifiers can uncover basic biological functions of CEP290, photoreceptor cilia, and their gestalt contributions to retinal disease in a physiologic context. From a clinical perspective, identification of genetic modifiers offers an opportunity to identify therapeutic surrogates. The premise for our current proposal, its feasibility, and evidence of our ability to conduct quantitative modifier studies of retinal degeneration all stem from a relatively large body of recent work. We have performed large genetic crosses with mice and identified quantitative trait loci modifying retinal disease severity of mice homozygous for the Cep290rd16 mutation. Among regions of the genome identified as particularly important, our current proposal focuses on the Modifier of retinal degeneration quantitative trait locus 1 (Mrdq1) located on mouse chromosome 12. A unique feature of this modifier that has aided our ability to identify its molecular basis is that it shows imprinting—its influence varies according to parent-of-origin. Using physical mapping in combination with a study of retinal expressed genes that are imprinted, we have identified an overt mutation within a previously unstudied microRNA that is highly likely to be the causative mutation. Experiments of this proposal describe the work to stringently confirm that we have identified the precise mutation underlying the Mrdq1 modifier (Specific Aim 1), and begin to study its mechanisms of action through identification of downstream targets of the microRNA present in photoreceptors. At completion, we expect this work to have impact on CEP290-mediated LCA, as well as promote a better understanding of how two understudied phenomena, gene regulation via microRNAs and imprinting, influence retinal disease.