Defining the cellular role of TMCO1, a glaucoma-linked gene of unknown function

定义 TMCO1（一种功能未知的青光眼相关基因）的细胞作用

• 批准号: 9092399
• 负责人: Robert J Keenan
• 金额: $ 23.14万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9092399
• 关键词: Affect; American; Anabolism; Apoptosis; Apoptosis Regulation Gene; Apoptotic; Bacterial Proteins; Biochemical; Biochemistry; Biogenesis; Biological Assay; Blindness; Cell Extracts; Cell Survival; Cells; Cellular Membrane; Cessation of life; Data; Defect; Dependence; Development; Disease; Endoplasmic Reticulum; Eye; Future; Genes; Glaucoma; Goals; Human; In Vitro; Induction of Apoptosis; Integral Membrane Protein; Knock-out; Lead; Link; Mass Spectrum Analysis; Membrane; Membrane Proteins; Microscopy; Microsomes; Modeling; Molecular; Monitor; Neurodegenerative Disorders; Optic Nerve; Pathogenesis; Pathway interactions; Patients; Phylogenetic Analysis; Population; Positioning Attribute; Prevalence; Primary Open Angle Glaucoma; Protein Biosynthesis; Proteins; Proteome; Proteomics; Retinal Ganglion Cells; Ribosomes; Role; Single Nucleotide Polymorphism; Staging; System; Tissues; Work; base; disease phenotype; genome wide association study; high risk; human disease; in vivo; insight; member; novel; novel therapeutic intervention; public health relevance; research study

 DESCRIPTION (provided by applicant): The goal of this project is to define the cellular role of TMCO1, a glaucoma-linked gene which encodes an integral membrane protein of unknown function. More than two million Americans are affected by glaucoma, a group of neurodegenerative diseases involving optic nerve damage resulting from the apoptotic death of retinal ganglion cells (RGC). Despite its prevalence, little is known about the development and progression of glaucoma on the molecular level. Multiple genome-wide association studies in different populations have recently identified associations between primary open angle glaucoma (POAG)-the most common form of glaucoma-and single nucleotide polymorphisms (SNPs) around a gene called TMCO1. Intriguingly, some of these SNPs are correlated with changes in expression levels of the TMCO1 gene. That such changes contribute to the pathogenesis of glaucoma is consistent with previous studies suggesting that TMCO1 is an apoptosis regulator expressed in multiple eye tissues, including RGCs. However, the role of TMCO1 in glaucoma remains unknown, because its cellular and molecular functions are completely undefined. We recently uncovered a possible function for TMCO1 as a result of a phylogenetic analysis. We found that TMCO1 belongs to a previously unrecognized superfamily of distantly related proteins that are broadly involved in membrane protein biogenesis. Furthermore, we have obtained functional data showing that TMCO1 localizes to the endoplasmic reticulum (ER) membrane where it interacts with ribosomes and other components of the known biosynthetic machinery. Based on these preliminary data, we hypothesize that TMCO1 functions to insert certain membrane proteins into the ER during their biosynthesis. An attractive model is that defects in TMCO1-dependent insertion lead to misfolding, accumulation of toxic aggregates and induction of apoptosis, hallmarks of many neurodegenerative diseases. Alternatively, the disease phenotype might be linked to failed biogenesis of a specific protein(s) that is essential for normal RGC survival. We are uniquely positioned to define the cellular role of TMCO1 using quantitative proteomics, cell-based localization studies and in vitro biochemistry. In Aim 1 we will identify human membrane proteins whose biogenesis is dependent on TMCO1. In Aim 2 we will develop an in vitro insertion assay and demonstrate that TMCO1 is a bona fide insertase. This is a high-risk project that promises high-impact payoff. By defining the function of TMCO1 and identifying substrates on which it acts, these studies will provide a molecular framework to understand how changes in TMCO1 expression are linked to the development of glaucoma. More broadly, if our hypothesis is correct, we will have discovered a new membrane protein insertion system in the endoplasmic reticulum. Such work would impact our understanding of membrane protein biogenesis and its role in human disease.

 描述（由申请人提供）：该项目的目标是确定 TMCO1 的细胞作用，TMCO1 是一种青光眼相关基因，编码功能未知的整合膜蛋白。超过 200 万美国人患有青光眼，这是一组神经退行性疾病，涉及因视网膜神经节细胞 (RGC) 凋亡导致的视神经损伤。尽管青光眼很普遍，但人们对青光眼在分子水平上的发生和进展知之甚少。 最近在不同人群中进行的多项全基因组关联研究确定了原发性开角型青光眼 (POAG)（最常见的青光眼形式）与 TMCO1 基因周围的单核苷酸多态性 (SNP) 之间的关联。有趣的是，其中一些 SNP 与 TMCO1 基因表达水平的变化相关。这些变化导致青光眼的发病机制与之前的研究一致，表明TMCO1是在多种眼组织（包括RGC）中表达的细胞凋亡调节因子。然而，TMCO1 在青光眼中的作用仍然未知，因为其细胞和分子功能完全未定义。 我们最近通过系统发育分析发现了 TMCO1 的可能功能。我们发现 TMCO1 属于一个以前未被识别的远亲蛋白超家族，广泛参与膜蛋白的生物发生。此外，我们获得的功能数据显示 TMCO1 定位于内质网 (ER) 膜，在那里它与核糖体和已知生物合成机制的其他成分相互作用。 基于这些初步数据，我们假设 TMCO1 的功能是在生物合成过程中将某些膜蛋白插入内质网。一个有吸引力的模型是，TMCO1 依赖性插入的缺陷会导致错误折叠、有毒聚集物的积累和细胞凋亡的诱导，这是许多神经退行性疾病的标志。或者，疾病表型可能与特定蛋白质的生物发生失败有关 这对于 RGC 的正常生存至关重要。我们拥有独特的优势，可以利用定量蛋白质组学、基于细胞的定位研究和体外生物化学来定义 TMCO1 的细胞作用。在目标 1 中，我们将鉴定其生物发生依赖于 TMCO1 的人类膜蛋白。在目标 2 中，我们将开发一种体外插入测定并证明 TMCO1 是一种真正的插入酶。这是一个高风险项目，但有望带来高影响力的回报。通过定义 TMCO1 的功能并确定其作用的底物，这些研究将提供一个分子框架来了解 TMCO1 表达的变化如何与青光眼的发展相关。更广泛地说，如果我们的假设是正确的，我们将在内质网中发现一种新的膜蛋白插入系统。此类工作将影响我们对膜蛋白生物发生及其在人类疾病中的作用的理解。