Identification of arthritis genes in DAxF344 congenic rats.

描述（由申请人提供）：大鼠胶原诱导关节炎（CIA）和蛋白酶诱导关节炎（PIA）是成熟的实验动物模型，已被用于深入了解类风湿关节炎（RA）的发病机制，类风湿关节炎是一种在大多数人群中患病率为1%的慢性致残性疾病。CIA、PIA和RA是由MHC和非MHC基因调控的复杂性状疾病。非mhc基因占RA遗传贡献的50-75%，但对这些基因知之甚少。该提议的基本假设是，控制大鼠CIA和PIA易感性和严重程度的非mhc位点将与了解RA的发病机制高度相关，并可能为开发更特异性的治疗方法提供新的靶点，以及诊断和预后的新工具。在本研究提出之前的实验中，对MHC不一致的自交系关节炎易感性DA和关节炎抗性F344大鼠菌株的F2杂交进行了全基因组筛选，分别在染色体4、10和8上发现了3个非MHC数量性状位点Cia3、Cia5和Cia6。这些qtl的关节炎调节作用在基因型引导的同源菌株中得到证实，其中f344衍生的区间逐渐渗入DA背景。这些qtl同源菌株受到保护，并发展出明显较温和的关节炎形式。基于这些先前的研究，我们假设CIA和PIA的强大和高渗透性表型取决于Cia3， Cia5和Cia6的易感等位基因的存在。此外，Cia3和Cia5位于含有RA易感基因的同源区域，表明相同的基因可能调节两种物种的关节炎。这一建议旨在识别和表征这些基因。目的1完成亚同源菌株的构建，将含有关节炎基因的关键区域减少到<1Mb。与关节炎相关的亚表型将在基因中被识别和研究，以获得基因功能和身份的早期线索。目的是对关键区域内的2个候选基因进行测序和分析，以确定区分DA和F344的致病多态性/突变。鉴定的基因和疾病变异将在体外和体内研究中进行功能表征。

DESCRIPTION (provided by applicant): Collagen-induced arthritis (CIA) and pristane-induced arthritis (PIA) in rats are well-established experimental animal models that have been used to gain insight into the pathogenesis of rheumatoid arthritis (RA), a chronic and commonly disabling disease with a prevalence of 1% in most populations. CIA, PIA and RA are complex trait diseases regulated by MHC and non-MHC genes. Non-MHC genes account for 50-75% of the genetic contribution to RA, yet, little is known about those genes. The underlying hypotheses of this proposal are that the non-MHC loci governing susceptibility to and severity of CIA and PIA in rats will be highly relevant to understanding the pathogenesis of RA and could generate new targets for the development of more specific therapies, as well new tools for diagnosis and prognosis. In experiments leading up to the present proposal, a genome-wide screen done in a F2 intercross between the MHC discordant inbred arthritis-susceptible DA and the arthritis-resistant F344 rat strains identified three non-MHC quantitative trait loci (QTL) Cia3, Cia5 and Cia6 on chromosomes 4, 10 and 8, respectively. The arthritis-regulatory effect of these QTLs was confirmed in genotype-guided congenic strains where the F344-derived interval was introgressed into the DA background. These QTL-congenic strains were protected and developed a significantly milder form of arthritis. Based on these prior studies, it is hypothesized that the robust and highly penetrant phenotype of CIA and PIA depends on the presence of susceptibility alleles at Cia3, Cia5 and Cia6. Additionally, Cia3 and Cia5 are located in regions homologous to those containing RA susceptibility genes, suggesting that the same genes might regulate arthritis on both species. This proposal aims at identifying and characterizing those genes. On aim 1 the construction of subcongenic strains will be completed in order to reduce the critical regions containing the arthritis genes to <1Mb. Subphenotypes relevant to arthritis will be identified and studied in congenics to obtain early clues to gene function and identity. On aim 2 candidate genes within the critical regions will be sequenced and analyzed for disease-causing polymorphisms/mutations that differentiate DA from F344. The identified genes and disease variants will be functionally characterized in in vitro and in vivo studies.