Autoimmunity-associated genes in new rat models: validation of human GWAS genes

描述（由申请人提供）：我们的知识空白：最近，已经检测到许多具有引发或延续自身免疫性疾病潜力的遗传基因座，其中许多是通过全基因组关联研究（GWAS）发现的。 然而，GWAS的结果有时很难解释，匿名SNP关联的实用性受到质疑。数量性状基因座（QTL）和GWAS的基础基因需要验证和测试， 识别组织和它们起作用的关键功能途径。有一个优秀的动物对应物来测试关于非MHC基因如何控制自身免疫的假设，而不受人类研究的伦理和实践考虑的影响，这将是有利的。有效的啮齿动物模型是那些：（1）在同一疾病中显示出在GWAS同源物处需要易感等位基因，（2）在GWAS同源物处具有变异，（3）在GWAS同源物处具有变异，（4）在GWAS同源物处具有变异，（5）在GWAS同源物处具有变异。 候选基因的表达或编码序列，以便可以比较抗性和易感等位基因，和（3）具有可测量的基因与环境和基因与基因的相互作用，这可能是必要的， 促进人类和啮齿动物群体的自身免疫。我们提出的模型符合这些标准。 新奇和风险：1型糖尿病（TlD）是T细胞介导的自身免疫性疾病，并且GWAS已经发现了>18种显著的非MHC糖尿病促进关联。在我们的新型T1 D大鼠模型中，具有良好的临床保真度和对环境干扰物的绝对依赖性，我们诱导T1 D响应于暴露于病毒和TLR激动剂。我们已经将两个高度显着的大鼠QTL定位到包含两个人类GWAS基因候选者的直系同源物的区域：二泛素（UBD或FAT 10）和UBASH 3A。该模型符合上述所有三个标准，有可能研究这些基因在糖尿病诱导中的作用。风险在于，在糖尿病发生中，两个物种都不需要UBD或UBASH 3A的疾病连锁等位基因，并且人类和大鼠的作图项目都给出了两个不正确的候选基因。 潜在的突破/与使命的相关性：这项工作将探索UBD和/或UBASH 3A在易感大鼠中创建有利于糖尿病发作的环境以应对病毒感染的方式，并可以提供人类直系同源物做同样事情的方式的忠实模型。这两个候选者都在泛素途径中起作用，已经涉及T淋巴细胞活化，而UBD 转录本也存在于胰腺中。一个重要的结果将是显示增强的病毒后泛素介导的关键T细胞或β细胞调节途径成员的降解可导致T1 D。 目标1.检验UBD和UBASH 3A是重组同源大鼠中T1 D候选基因的假设。目的2：确定病毒感染后UBD和/或UBASH 3A基因表达升高是否是糖尿病表型的基础。确定人类UBD启动子，如大鼠UBD启动子，是否在体外报告基因测定中显示启动子活性的等位基因差异。目标3.通过混合匹配新生儿过继性T细胞转移和病毒诱导T1 D，确定两个大鼠糖尿病基因座启动T1 D的组织。 公共卫生相关性：自身免疫是一个严重的公共卫生问题，影响近2000万美国居民。1型自身免疫性糖尿病（T1 D）的患病率正在增加，发病时间正在减少;在美国青年中，新发病例的发生率为1/600。在环境因素的背景下，许多基因易患T1 D。我们的建议旨在开发一种病毒诱导的T1 D大鼠模型，其中我们绘制了胰腺β细胞自身免疫破坏所需的两个基因。每个人都有一个人类糖尿病修饰直系同源物。这种新的大鼠模型将允许一种新的方法来探索和研究这些基因，并基于它们共享的泛素和途径以及T细胞定位来探索潜在的治疗方法。

DESCRIPTION (provided by applicant): Gaps in our knowledge: Recently, numerous genetic loci with the potential to initiate or perpetuate auto- immune disease have been detected, many of them found by genome-wide association studies (GWAS). However, GWAS results are sometimes difficult to interpret, and the utility of anonymous SNP association has been questioned. Genes underlying quantitative trait loci (QTL) and GWAS need verification and testing to identify the tissue and the critical functional pathways in which they act. It would be advantageous to have an excellent animal counterpart to test hypotheses about how non-MHC genes control autoimmunity unimpaired by the ethical and practical considerations of human research. Effective rodent models would be those that: (1) display the need for a susceptible allele at a GWAS homologue in the same disease, (2) have variation in expression or coding sequence of the candidate gene, so that resistant and susceptible alleles can be compared, and (3) have measurable gene-by-environment and gene-by-gene interaction that is likely necessary to promote autoimmunity in both the human and rodent populations. Our proposed model fulfils those criteria. Novelty and Risk: Type 1 diabetes (T1D) is a T cell mediated autoimmune disease, and >18 significant non- MHC diabetes-promoting associations have been discovered by GWAS. In our novel rat model of T1D with excellent clinical fidelity and an absolute dependence on environmental perturb ants, we induce T1D in response to exposure to viruses and TLR agonists. We have mapped two highly significant rat QTL to regions containing two orthologues of human GWAS gene candidates: diubiquitin (UBD or FAT10) and UBASH3A. This model meets all three criteria above for potential to study how these genes act in diabetes induction. The risk is that neither species requires a disease-linked allele of UBD or UBASH3A in diabetogenesis, and that both human and rat mapping projects have given two incorrect candidate genes. Potential breakthroughs/relevance to mission: This work will explore the manner in which UBD and/or UBASH3A creates an environment conducive to the onset of diabetes in response to viral infection in susceptible rats, and could provide a faithful model of the way the human orthologues do the same thing. Both these candidates function in the ubiquitin pathway, already implicated in T lymphocyte activation, and the UBD transcripts are also found in the pancreas. One important outcome would be to show that enhanced post-viral ubiquity-mediated degradation of key T cell or beta-cell regulatory pathway members can lead to T1D. Aim 1. Test the hypothesis that UBD and UBASH3A are T1D candidate genes in recombinant congenic rats. Aim 2: Determine if heightened UBD and/or UBASH3A gene expression after virus infection underlie the diabetes phenotype. Determine if human UBD promoters, like the rat UBD promoter, show allelic differences in promoter activity in an in vitro reporter assay. Aim 3. Determine the tissue in which the two rat diabetes loci act to initiate T1D, with mix-and-match neonatal adoptive transfer of T cells and viral induction of T1D. PUBLIC HEALTH RELEVANCE: Autoimmunity is a serious public health issue that affects nearly 20 million US residents. Type 1 autoimmune diabetes (T1D) is increasing in prevalence and decreasing in time-to-onset; new cases appear at a rate of 1/600 in US youth. Numerous genes predispose to T1D in the context of environmental factors. Our proposal is designed to develop a rat model of virus-induced T1D in which we have mapped two genes required for autoimmune destruction of the pancreatic beta cells. Each has a human diabetes-modifying orthologue. This novel rat model will allow a fresh approach to explore and study these genes and probe potential therapies 9 based on their shared ubiquitin and pathway and T cell localization.