Pathogenesis of age-related Fuchs Endothelial Corneal Dystrophy

年龄相关性福克斯内皮性角膜营养不良的发病机制

• 批准号: 9055004
• 负责人: MICHAEL P. FAUTSCH
• 金额: $ 51.97万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9055004
• 关键词: Allogenic; Antithymoglobulin; BHLH Protein; Biological Models; Blindness; Cataract Extraction; Cell Culture Techniques; Cell Nucleus; Cell physiology; Cells; Cerebellar Ataxia; Chromosomes, Human, Pair 18; Clinical; Cornea; Corneal Endothelium; Corneal edema; DNA; Data; Degenerative Disorder; Deposition; Development; Disease; Disease Progression; Endothelial Cells; Event; Extracellular Matrix; Eye diseases; Fragile X Syndrome; Fuchs' Endothelial Dystrophy; Future; Gene Expression; Genes; Genetic; Genetic Transcription; Genomics; Homeostasis; Huntington Disease; Individual; Introns; Keratoplasty; Knowledge; Lasers; Left; Length; Light; Link; Mediating; Medical; Mesenchymal; Messenger RNA; Modeling; Molecular; Myotonic Dystrophy; Operative Surgical Procedures; Oxidative Stress; Pathogenesis; Patients; Peptides; Phenotype; Physiological; Platelet Factor 4; Positioning Attribute; Postoperative Period; Protein Family; Protein Kinase; Proteins; Publishing; RNA; RNA Splicing; Research; Risk; Role; Staging; Stress; Syndrome; Testing; Tissues; Transcript; Translations; Transplantation; Trinucleotide Repeat Expansion; Untranslated RNA; Work; age related; base; endoplasmic reticulum stress; genetic variant; member; monolayer; nervous system disorder; novel; novel therapeutic intervention; polyglutamine; protein aggregate; protein function; public health relevance; research study; response; stressor; targeted treatment; therapeutic development; transcription factor

 DESCRIPTION (provided by applicant): This is a multiple PI R01 application to test the hypothesis that trinucleotide repeat expansion (TNR) is a causal event in the pathogenesis of Fuchs endothelial corneal dystrophy (FECD). FECD is a common, degenerative disease of the corneal endothelial cell monolayer. Unfortunately, there are no medical therapies to halt disease progression, and the pathogenesis is not well understood. As a result, surgical transplantation of the cornea is the only viable treatment. In fact, end-stage FECD is the most common cause of allogeneic corneal transplantation in the U.S., responsible for greater than 14,000 grafts annually. Recently, we have identified a CTG TNR expansion sequence within the third intron of the transcription factor 4 (TCF4) gene that associates with 79% of FECD cases. To date, this is the most predictive genetic anomaly identified for FECD. In FECD, CTG TNR expansions range from 50-2000 repeats, which are significantly higher than non-FECD patients who typically have 12-18 CTG repeats. How this TCF4 CTG TNR expansion region promotes the FECD phenotype is not clear. Similar expansion of unstable TNR sequences have been identified as the causative pathogenic mechanism in several rare and debilitating neurologic disorders, such as spin cerebellar ataxias, Huntington disease, fragile X syndrome and myotonic dystrophy, type 1. These TNR expansion regions are thought to interfere with normal protein function, expression of the TNR containing gene, and/or RNA splicing in cis and trans. In addition, translation of toxic Repeat-Associated Non-ATG (RAN) translation products from the sense and antisense transcripts of the TNR expansion sequences have also been identified as a contributing factor towards disease progression. Our preliminary studies suggest similar events are occurring in FECD cells. According to our data, transcripts from the TCF4 CTG TNR expansion region are retained in the nucleus and form ribonuclear inclusions called RNA foci in FECD tissue and primary FECD monolayer cells. These RNA foci sequester the splicing factor MBNL1, leading to altered splicing of numerous transcripts. We also have evidence for RAN translation of TCF4 CTG TNR expansion RNA, producing small homopolymeric protein aggregates in corneal endothelial cells of FECD patients. Our central hypothesis is that RNA foci and RAN translation protein products arising from the TCF4 CTG TNR expansion region causes FECD by altering gene expression and disrupting critical cell functions. It is our premise that stress factors (e.g. oxidative stress) promote instability in the TCF4 CTG TNR expansion sequence resulting in the formation of CUG repeat containing RNA foci and accumulation of RAN translation products. The presence of these products leads to differential mRNA splicing and altered expression of critical genes, stimulating ER stress-mediated activation of unfolded protein response (UPR), endothelial to mesenchymal transformation (EMT) and disordered extracellular matrix (ECM) deposition. We will test our hypothesis with two specific aims - 1) Characterize the molecular anomalies associated with TCF4 CTG TNR expansion in FECD; 2) Determine the role of TCF4 CTG TNR expansion in pathogenesis of FECD. Completion of these two specific aims will provide a mechanistic understanding of how TCF4 CTG TNR expansion is involved in FECD pathogenesis. Understanding the molecular events underlying the pathogenesis of FECD will be essential for future development of targeted therapeutic strategies for management of FECD.

 描述（由申请方提供）：这是一项多PI R 01申请，旨在检验三核苷酸重复扩增（TNR）是Fuchs内皮角膜营养不良（FECD）发病机制中的因果事件的假设。FECD是一种常见的角膜内皮细胞单层退行性疾病。不幸的是，没有药物治疗来阻止疾病进展，并且发病机制还没有很好地理解。因此，手术角膜移植是唯一可行的治疗方法。事实上，在美国，终末期FECD是同种异体角膜移植最常见的原因，每年有超过14,000例移植手术最近，我们在转录因子4（TCF 4）基因的第三内含子内鉴定了CTG TNR扩增序列，该序列与79%的FECD病例相关。到目前为止，这是FECD最具预测性的遗传异常。在FECD中，CTG TNR扩增范围为50-2000个重复，这显著高于通常具有12-18个CTG重复的非FECD患者。该TCF 4 CTG TNR扩增区域如何促进FECD表型尚不清楚。不稳定TNR序列的类似扩增已被鉴定为几种罕见的和使人衰弱的神经系统疾病的致病机制，例如旋转小脑共济失调、亨廷顿病、脆性X综合征和1型肌强直性营养不良。这些TNR扩增区域被认为干扰正常蛋白质功能、含有TNR的基因的表达和/或RNA顺式和反式剪接。 来自TNR扩增序列的正义和反义转录物的重复相关非ATG（RAN）翻译产物也已被鉴定为导致疾病进展的因素。我们的初步研究表明，类似的事件发生在FECD细胞。根据我们的数据，来自TCF 4 CTG TNR扩增区的转录物保留在细胞核中，并在FECD组织和原代FECD单层细胞中形成称为RNA灶的核糖核内含物。这些RNA焦点隔离剪接因子MBNL 1，导致许多转录物的剪接改变。我们也有TCF 4 CTG TNR扩增RNA的RAN翻译的证据，在FECD患者的角膜内皮细胞中产生小的均聚蛋白质聚集体。我们的中心假设是TCF 4 CTG TNR扩增区产生的RNA灶和RAN翻译蛋白产物通过改变基因表达和破坏关键细胞功能导致FECD。这是我们的前提，压力因素（例如， 氧化应激）促进TCF 4 CTG TNR扩增序列的不稳定性，导致形成含有CUG重复的RNA焦点和RAN翻译产物的积累。这些产物的存在导致差异mRNA剪接和关键基因的表达改变，刺激ER应激介导的未折叠蛋白反应（UPR）激活、内皮细胞向间充质转化（EMT）和无序细胞外基质（ECM）沉积。我们将用两个具体目标来检验我们的假设：1）表征与FECD中TCF 4 CTG TNR扩增相关的分子异常; 2）确定TCF 4 CTG TNR扩增在FECD发病机制中的作用。这两个具体目标的完成将提供对TCF 4 CTG TNR扩张如何参与FECD发病机制的机制理解。了解FECD发病机制的分子事件对于未来开发FECD管理的靶向治疗策略至关重要。