Genetic dissection of Sle2 contribution to SLE pathogenesis

描述（由申请方提供）：本提案的目的是鉴定NZM 2410小鼠模型中负责Sle 2狼疮相关表型的基因，并表征这些基因促进狼疮发病机制的机制。 因此，Sle 2，一个影响B细胞发育和功能的遗传基因座，在自身免疫发病机制中起主要作用。 我们最近已经确定了三个独立的Sle 2区域，Sle 2a，Sle 2B，和Sle 2c，影响B-1a细胞池的大小，但只有其中两个，Sle 2a和Sle 2B有助于自身免疫发病机制。Sle 2通过多种机制影响perC B-1a细胞的数量，这可以通过三个Sle 2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）使用56 R抗DNA重链转基因模型表明Sle 2介导耐受性的破坏。 基于这些最新的结果和我们一直使用的策略来表征Sle 1基因，我们提出了以下三个目标来识别Sle 2基因：1。生成Sle 2a、Sle 2b和Sle 2c基因座的高分辨率遗传图谱。 我们将生产B6.Sle 2同源重组亚株，并筛选它们的perC B-1a细胞池增加。这个过程将被迭代，直到每个基因座都被映射到< 0.5 cM的临界区间。 此外，我们将使用每个Sle 2基因座与其他SLE易感基因座之间的相互作用作图方法监测B-1a表型与狼疮发病机制的共分离。2. 表征与3个Sle 2基因座中的每一个相关的表型。 在遗传作图的同时，我们将完善每个Sle 2基因座的表型定义。 这一目标具有双重目标，即阐明这些基因座有助于疾病机制的机制，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）将Sle 2增加B-1a细胞池的每种机制分配给特定的Sle 2基因座，2）比较表达每个Sle 2基因座的perC B-1a细胞的基因表达谱，3）使用56 R模型确定三个Sle 2基因座中的哪一个负责对核抗原的耐受性丧失。3.为了鉴定对应于Sle 2a、Sle 2b和Sle 2c的基因。 目的1和2将提供每个Sle 2基因座的位置和功能候选基因的列表。 B6和B6.Sle2同源菌株之间的序列和表达多态性将系统地表征这些基因。 然后将在同类菌株之间评价这些多态性相对于B细胞功能的功能性。 功能多态性的存在和在临界区间内的位置之间的一致性将提供强有力的证据，该特定基因的NZM 2410等位基因负责相应的SLE易感性表型。

DESCRIPTION (provided by applicant): The purpose of this proposal is to identify the genes responsible for the Sle2 lupus-associated phenotypes in the NZM2410 murine model, and to characterize the mechanisms by which these genes contribute to lupus pathogenesis. Consequently, Sle2, a genetic locus that affects B cell development and function, plays a major role in autoimmune pathogenesis. We have recently identify three independent Sle2 regions, Sle2a, Sle2b, and Sle2c, that affect the size of the B-1a cell pool, but only two of them, Sle2a and Sle2b contribute to autoimmune pathogenesis. Sle2 affects the number of perC B-1a cells through multiple mechanisms, which could be mediated independently through each of the three Sle2 loci. Finally, our long-time collaborator Dr. Chandra Mohan (UTSW) has shown that Sle2 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 Sle2 genes: 1. To generate high resolution genetic maps of the Sle2a, Sle2b, and Sle2c loci. We will produce B6.Sle2 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 Sle2 loci with other SLE susceptibility loci. 2. To characterize the phenotypes associated with each of the 3 Sle2 loci. Concurrent with the genetic mapping effort, we will refine the phenotypic definition of each Sle2 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 Sle2 increases the B-1a cell pool to specific Sle2 loci, 2) compare the gene expression profile of perC B-1a cells expressing each Sle2 locus, and 3) determine which of the three Sle2 loci is responsible for the loss of tolerance to nuclear antigens using the 56R model. 3. To identify the genes corresponding to Sle2a, Sle2b, and Sle2c. Aims 1 and 2 will provide a list of positional and functional candidate genes for each of the Sle2 loci. Sequence and expression polymorphisms between the B6 and the B6.Sle2 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.