Characterization of SLE Loci on Mouse Chromosome 1

描述(申请人提供)：Sle1是系统性红斑狼疮NZM2410小鼠模型中最强的易感基因。我们已经证明，它介导了对核抗原耐受性的丧失，并且它的表达是疾病完全重建所必需的。在开发SLE-1高分辨率图谱的过程中，我们已经证明它对应于Sle1a、Sle1b和Sle1c三个基因座，每个基因座都会产生抗核抗原的自身抗体，但淋巴细胞标志物的表达谱不同，这表明它们属于不同的功能途径。在对这些基因进行基因鉴定工作的同时，我们建议表征这些基因座如何单独、相互结合或与其他SLE易感基因一起对SLE发病起作用。这项研究是必要的，因为在大多数情况下，基因识别并不提供有关该特定基因参与疾病过程的机制的信息。此外，对多基因自身免疫性疾病的分析清楚地表明，发病机制是弱基因之间相互作用的结果。在这项提议的最初资助期间，我们已经开发了一个独特的模型，根据表型分析的收益来剖析这些相互作用。我们的模型现在包括大量的同源菌株，这些菌株要么包含具有单个易感基因位点的小基因组间隔，要么包含它们的各种组合。我们还编制了一个与这些菌株相对应的组织和表型的大型数据库。这一建议有四个具体目标：1)描述Sle1a、Sle1b和Sle1c对淋巴细胞功能的影响，并剖析这些基因座之间的相互作用。这些实验将结合与每个基因座相关的B和T细胞发育的特征，UMT和TCRA零突变的培育来评估Sle1基因座对固有的B和T细胞缺陷的影响，以及用于分析相互作用的骨髓嵌合体；2)从遗传学和功能上评估Cr2作为Sle1c的候选基因。我们将产生重组体来评估Sle1c是否与Cr2共分离，产生BM嵌合体来定位Sle1c在B细胞和FDC之间的功能表达，并利用3H9 SD-TG系统来评估Sle1c在抗dsDNA耐受中的作用；3)以IPR、Yaa和Sles1为模型，评估Sle1a、Sle1b和Sle1c与其他SLE基因座的相互作用。我们已经证明，Sle1与YaA或LPR共表达导致了高度渗透性的SLE，而Sles1关闭了Sle1的表型，并且每个Sle1基因座与这些基因座进行了不同类型的相互作用。我们建议使用这个系统来剖析相互作用在SLE发病机制中的作用和机制，使用免疫学特征基因表达谱，以及骨髓嵌合体方法来追踪表达致病基因组合的B细胞的命运。4)表征10号和11号染色体上的两个新的易感基因座及其与Sle1的相互作用。已经确定了两个新的易感基因座，我们建议将它们与Sle1结合起来，以表征它们对疾病的贡献并绘制它们的位置图。这些实验是多个团队努力的一部分，目的是识别和表征导致主要SLE易感基因的基因，以便能够设计对这些基因及其功能途径的治疗干预措施。

DESCRIPTION (provided by applicant): Sle1 is the strongest susceptibility locus in the NZM2410 mouse model of SLE. We have shown that it mediates the loss of tolerance to nuclear antigens, and that its expression is required for full reconstitution of the disease. In the process of developing a high resolution map of Sle 1, we have demonstrated that it corresponds to three loci, Sle1a, Sle1b, and Sle1 c. Each of these loci results in autoantibodies against nuclear antigens, but in a different profile of lymphocyte marker expression, suggesting that they belong to different functional pathways. In parallel with gene identification efforts being conducted on these genes, we propose to characterize how these loci contribute to SLE pathogenesis, either by themselves, in combinations with each other, or in combination with other SLE-susceptibility genes. This study is necessary because, in most cases, gene identification does not provide information on the mechanisms by which this given gene is involved in the disease process. In addition, analyses of polygenic autoimmune diseases have clearly shown that pathogenesis results from interactions between weak loci. We have developed during the initial funding of this proposal a unique model to dissect out these interactions based on gain of phenotype analyses. Our model now comprises a large collection of congenic strains that either contain small genomic intervals with a single susceptibility locus, or various combinations of them. We have also compiled a large database of tissues and phenotypes corresponding to these strains. This proposal has four specific aims: 1) To delineate the impact of Sle1a, Sle1b, and Sle1c on lymphocyte functions and to dissect the interactions between these loci. These experiments will combine characterization of B and T cell development associated with each locus, breeding of the uMT and Tcra null mutations to assess the impact of the Sle1 loci on intrinsic B and T cells defects, and bone marrow chimeras to analyze interactions; 2) To evaluate genetically and functionally Cr2 as candidate gene for Sle1c. We will generate recombinants to assess whether Sle1c co-segregate with Cr2, produce BM chimeras to localize the functional expression of Sle1c between B cells and FDC, and evaluate the role of Sle1c in anti-dsDNA tolerance by using the 3H9 sd-tg system; 3) To assess how Sle1a, Sle1b, and Sle1c interact with other SLE loci, using Ipr, Yaa, and Sles1 as models. We have shown that Sle1 co-expression with either Yaa or lpr results into a highly penetrant SLE, while Sles1 shuts down Sle1 phenotypes, and that each Sle1 locus engages into a different type of interaction with these loci. We propose to use this system to dissect the role and mechanism of interactions in SLE pathogenesis, using immunological characterization gene expression profiling, and a bone marrow chimera approach to trace the fate of B cells expressing a pathogenic combination of loci.; 4) To characterize two new susceptibility loci on chromosomes 10 and 11 and their interaction with Sle1. Two new susceptibility loci have been identified and we propose to combine them with Sle1 to characterize their contribution to the disease and to map their location. These experiments are part of a multi team effort to identity and characterize the genes responsible for a major SLE-susceptibility locus in order to be able to design therapeutic interventions on these genes and their functional pathways.