The role of transcription factor 4 repeat expansion in Fuchs endothelial corneal dystrophy

 描述（由申请人提供）：这是一项多重PIR 21应用，用于检验三核苷酸重复序列（TNR）扩增在Fuchs内皮角膜营养不良（FECD）（一种常见的常染色体显性迟发性眼病）的发病机制中发挥作用的假设。在美国，由FECD引起的角膜水肿是角膜移植最常见的适应症。没有已知的药物治疗来阻止疾病进展，并且发病机制也不清楚。我们之前的工作已经确定转录因子4（TCF 4）基因中的TGC TNR扩增是该疾病最强大的生物标志物，存在于约80%的病例和3%的对照中。我们现在有初步的数据表明，转录TCF 4重复扩增形成RNA灶角膜内皮细胞从FECD患者。这一发现类似于强直性肌营养不良1型（DM 1），其中蛋白激酶基因3'非翻译区的相同三核苷酸扩增导致转录重复序列聚集成特征性核RNA灶，其隔离关键剪接因子肌盲样1（MBNL 1）。在DM 1中，有效MBNL1水平的降低改变了许多转录物的mRNA剪接模式，从而导致该疾病的临床表现谱。我们建议测试的假设，CTG重复TCF 4中的扩展同样改变剪接模式的FECD患者的角膜内皮细胞。次要目的包括分析TCF 4重复扩增对基因表达谱的影响，以及角膜内皮细胞基因组结构的广泛变化与FECD疾病进展之间的关系。我们的统一假设是FECD是一种TNR扩张性疾病。从机制上讲，我们假设该疾病是由于TNR扩增对角膜内皮（CE）基因表达的定性和定量影响所致。为了解决这个问题，我们将分析mRNA表达模式在患病和正常人CE，以确定如何基因表达模式改变FECD患者。相关性初步实验表明FECD是迄今为止描述的最常见的TNR扩张性疾病的假设。如果所提出的实验支持这一假设，它将提供深入了解致病机制，并提出新的方法来治疗FECD。目前还没有合理的方法来逆转TNR的扩张，因此我们对新型疗法的希望取决于详细说明FECD发病机制的分子基础。我们希望最终确定治疗靶点，以减轻疾病进展并减少对角膜移植的需求。

 DESCRIPTION (provided by applicant): This is a multiple PI R21 application to test the hypothesis that trinucleotide repeat (TNR) expansion plays a role in the pathogenesis of Fuchs endothelial corneal dystrophy (FECD), a common, autosomal dominant, late-onset eye disease. Corneal edema due to FECD is the most common indication for corneal transplantation in the United States. There are no known medical therapies to halt disease progression, and the pathogenesis is not well understood. Our previous work has identified a TGC TNR expansion in the transcription factor 4 (TCF4) gene as the most robust biomarker for the disease, being present in ~80% of cases and in 3% of controls. We now have preliminary data suggesting that transcripts from the TCF4 repeat expansion form RNA foci in corneal endothelial cells from FECD patients. This finding is analogous to myotonic dystrophy, type 1 (DM1) in which an identical trinucleotide expansion in the 3' untranslated region of a protein kinase gene leads to aggregation of the transcribed repeat sequence into characteristic nuclear RNA foci, which sequester the critical splicing factor muscleblind-like 1 (MBNL1). In DM1 the reduction in effective MBNL1 levels alters the patterns of mRNA splicing of numerous transcripts, contributing to the spectrum of clinical findings in the disease. We propose to test the hypothesis that expansion of CTG repeats in TCF4 similarly alters splicing patterns in the corneal endothelium from FECD patients. Secondary objectives will include analysis of the effect of TCF4 repeat expansion on gene expression profiles and the relationship between such widespread changes in the genomic architecture of corneal endothelial cells and disease progression in FECD. Our unifying hypothesis is that FECD is a TNR expansion disease. Mechanistically, we hypothesize that the disease results from both qualitative and quantitative effects of TNR expansion on gene expression in the corneal endothelium (CE). To address this issue, we will analyze mRNA expression patterns in diseased and normal human CE to determine how gene expression patterns are altered in FECD patients. Relevance Preliminary experiments suggest the hypothesis that FECD is the most common TNR expansion disease described to date. If the proposed experiments support this hypothesis, it will provide insight int pathogenic mechanisms and suggest novel approaches for treating FECD. There is no plausible way to reverse TNR expansion, so our hope for novel therapies depends upon detailing the molecular basis of FECD pathogenesis. We hope to eventually identify therapeutic targets to mitigate disease progression and reduce the need for corneal transplants.