Genetic dissection of Sle2 contribution to SLE pathogenesis

本研究的目的是鉴定S/e2狼疮相关表型的基因。 NZM 2410小鼠模型，并表征这些基因促成狼疮的机制 发病机制因此，S/e2，一个影响B细胞发育和功能的遗传位点，在B细胞中起着重要作用。 在自身免疫发病机制中的主要作用。我们最近确定了三个独立的S/e2区域，Sle 2a， Sle 2 B和S/e2 c影响B-1a细胞池的大小，但只有其中两个S/e2 a和Sle 2 B b起作用 自身免疫性发病机制S/e2通过多种机制影响perC B-1细胞的数量， 其可以通过三个S/e2基因座中的每一个独立地介导。最后，我们的长期 合作者Chandra Mohan博士（UTSW）已经表明，S/e2使用56 R介导了耐受性的破坏， 抗DNA重链转基因模型。基于这些最新的结果和我们的策略 Sle 1基因的特征，我们提出了以下三个目标来鉴定S/e2基因： 1.生成S/e2 a的高分辨率遗传图谱。Sle 2b和S/e2 c位点。我们将生产B6.S/e2 同源重组亚株，并筛选它们的增加的perC B-1a细胞池。这一进程将 迭代直到每个基因座已被映射到<0.5cM的临界区间。此外，我们亦会密切监察合- 使用相互作用作图法分离B-1a表型与狼疮发病机制 每个S/e2基因座与其他SLE易感基因座之间的接近。 2.表征与3个S/e2基因座中的每一个相关的表型。与遗传同时发生 在作图工作中，我们将完善每个S/e2基因座的表型定义。这一目标具有双重目标， 阐明这些基因座促进疾病机制的机制，并促进 目标3的候选基因的选择。为了实现这一目标，我们将1）分配每个机制 S/e2通过其将B-1a细胞池增加到特定的S/e2基因座，2）比较 perC B-1a细胞表达每个S/e2基因座，和3）确定三个S/e2基因座中的哪一个负责 使用56 R模型对核抗原的耐受性丧失。 3.鉴定S/e2 a对应的基因。sle 2b和S/e2 c。目标1和2将提供一份清单， 每个S/e2基因座的位置和功能候选基因。序列和表达 B6和B6.S/e2同源株之间的多态性将被系统地表征， 这些基因。然后评价这些多态性相对于B细胞功能的功能性 在同类菌株之间。功能多态性的存在与位置之间的一致性 在临界区间内，将提供强有力的证据表明，该特定基因的NZM 2410等位基因是 负责相应的SLE易感性表型。

The purpose of this proposal is to identify the genes responsible for the S/e2 lupus-associated phenotypes in the NZM2410 murine model, and to characterize the mechanisms by which these genes contribute to lupus pathogenesis. Consequently, S/e2, a genetic locus that affects B cell development and function, plays a major role in autoimmune pathogenesis. We have recently identify three independent S/e2 regions, Sle2a, Sle2b, and S/e2c, that affect the size of the B-1a cell pool, but only two of them, S/e2a and Sle2b contribute to autoimmune pathogenesis. S/e2 affects the number of perC B-1acells through multiple mechanisms, which could be mediated independently through each of the three S/e2 loci. Finally, our long-time collaborator Dr. Chandra Mohan (UTSW) has shown that S/e2 mediates a breach of tolerance using the 56R anti-DNA heavy chain transgenic model. Based on these recent results and on the strategy that we have been using to characterize the Sle1 genes, we propose the three following aims to identify the S/e2 genes: 1. To generate high resolution genetic maps of the S/e2a. Sle2b, and S/e2c loci. We will produce B6.S/e2 congenic recombinant sub-strains and screen them for increased perC B-1a cell pool. This process will be iterated until each locus has been mapped to a < 0.5 cM critical interval. In addition, we will monitor the co- segregation of the B-1a phenotype with the contribution to lupus pathogenesis using an interaction mapping approach between each of the S/e2 loci with other SLE susceptibility loci. 2. To characterize the phenotypes associated with each of the 3 S/e2 loci. Concurrent with the genetic mapping effort, we will refine the phenotypic definition of each S/e2 locus. This aim has the dual goal of elucidating the mechanisms by which these loci contribute to disease mechanisms, and facilitating the selection of candidate genes for Aim 3. To accomplish this goal, we will 1) assign each of the mechanisms by which S/e2 increases the B-1a cell pool to specific S/e2 loci, 2) compare the gene expression profile of perC B-1a cells expressing each S/e2 locus, and 3) determine which of the three S/e2 loci is responsible for the loss of tolerance to nuclear antigens using the 56R model. 3. To identify the genes corresponding to S/e2a. Sle2b, and S/e2c. Aims 1 and 2 will provide a list of positional and functional candidate genes for each of the S/e2 loci. Sequence and expression polymorphisms between the B6 and the B6.S/e2 congenic strains will be systematically characterized for these genes. The functionality of these polymorphisms relative to B cell functions will be then evaluated between the congenic strains. Congruity between the presence of a functional polymorphism and location within the critical interval will provide strong evidence that the NZM2410 allele of this specific gene is responsible for the corresponding SLE susceptibility phenotype.