Cr2 as a Murine Lupus Susceptibility Gene

描述（由申请人提供）：主要的小鼠系统性红斑狼疮（SLE）易感位点Sle1，对应于NZM2410小鼠中独立影响染色质耐受性丧失的3个位点。来自NZW的Sle1c对应的基因区间含有编码补体受体I和2 （CR1/ Cr2, CD35/CD21）的Cr2。在人类和动物模型中，CR1/CR2缺乏症与自身免疫性疾病有关。最近在Sle1c CR1/CR2中发现了一个关键配体结合域的结构差异，这导致受体功能的显著损伤。这些结果有力地支持了Cr2在Sle1c间期作为疾病易感基因的作用。本提案中概述的项目将直接用于表征NZW CR2在NZM2410狼疮小鼠模型中的作用。具体目的是证明CR2是NZM2410 Sle1c区间的狼疮易感基因，确定NZW CR2中对耐受性丧失至关重要的结构域，确定NZW CR2导致耐受性丧失的机制。证明CR2是Sle1c位点上的狼疮易感基因，将通过证明在正常基因产物存在的情况下，Sle1c表型会消退来提供证据。将评估含有窄间隔含有Cr2的重组菌株，以确保Cr2功能障碍继续跟踪自身免疫性疾病。将使用转染了重组蛋白的Cr2缺陷细胞系以及来自BAC转基因小鼠的表达各种形式的多态NZW Cr2的B细胞来确定导致自身免疫性表型的关键受体结构域。最后，NZW CR2等位基因改变导致B细胞耐受性丧失的机制将使用B细胞耐受性的3-83和HEL模型进行表征。这些研究将阐明在NZM2410小鼠模型中受损的CR2的特定功能，这些功能可能影响自身免疫性疾病的发展，从而成为治疗干预的重要靶点。

DESCRIPTION (provided by applicant): The major murine systemic lupus erythematosus (SLE) susceptibility locus, Sle1, corresponds to 3 loci independently affecting loss of tolerance to chromatin in the NZM2410 mouse. The congenic interval corresponding to Sle1c, derived from NZW, contains Cr2, which encodes complement receptors I and 2 (CR1/CR2, CD35/CD21). CR1/CR2 deficiency has been associated with autoimmune disease in both humans and in animal models. A structural difference in a critical ligand-binding domain has recently been identified in Sle1c CR1/CR2 which results in significant impairment in receptor function. These results strongly support the role of Cr2 as a disease susceptibility gene in the Sle1c interval. The project outlined in this proposal will be directed towards characterizing the role of NZW CR2 in the NZM2410 mouse model for lupus. The specific aims are to prove that CR2 is the lupus susceptibility gene in the NZM2410 Sle1c interval, to identify the structural domains in NZW CR2 that are critical in loss of tolerance, and to determine the mechanisms by which NZW CR2 results in loss of tolerance. Proof that CR2 is the lupus susceptibility gene in the Sle1c locus will be provided by demonstrating that the Sle1c phenotypes resolve in the presence of normal gene products. Recombinant strains that contain narrowed intervals containing Cr2 will be assessed to ensure that CR2 dysfunction continues to track with autoimmune disease, The critical receptor domains that result in the autoimmune phenotypes will be determined, using both CR2-deficient cell lines transfected with recombinant proteins as well as B cells from BAC transgenic mice that express various forms of the polymorphic NZW CR2. Finally, the mechanisms by which the altered NZW CR2 allele results in loss of B cell tolerance will be characterized using the 3-83 and HEL models for B cell tolerance. These studies will clarify the specific functions of CR2, impaired in the NZM2410 mouse model, that may impact on the development of autoimmune disease and thus be important targets for therapeutic interventions.