Genetic Dissection of B-Cell Signaling Pathways in Lupus

小鼠1号染色体上的Sle1和小鼠7号染色体上的SLES代表了狼疮最强的两个基因座 在NZM2410小鼠模型中。而仅有Sle1基因改造的正常(B6)小鼠表现出轻度狼疮， 携带这两个基因的正常小鼠会患上严重的狼疮。因此，B6、B6.Sle1z和B6.Sle1z.Sle3z 同源菌株捕捉了狼疮疾病发展的三个不同阶段，这让人想起在 人类狼疮的发展。最近，我们记录了这些小鼠中的B细胞表现出 多条信号通路的渐进性激活，包括AKT/mTOR轴，各种标记 通路，NFkB，STATS和STATS，以及不同的Bcl2家族成员，以及激活水平 与疾病的严重性有很好的相关性。我们还了解到，最强大的亚种的候选基因- Slelz内的SLAM/Ly108以B细胞固有的方式发挥作用，打破了早期B细胞的耐受性。 尽管SleSz的致病基因尚不清楚，但很明显，SleSz会影响DC的功能 和B细胞的内在联系。基于这些观察，我们提出了三个目标。 目的1.确定SLELZ B细胞中上调的信号通路是否是 自身抗原的慢性刺激和/或正常人和狼疮之间的多态差异- Ly108的相关等位基因/异构体。我们将确定慢性bcr刺激以及狼疮- 相关的Ly108.1和Sle1b/SLAM的“正常”Ly108.2亚型可能参与信号转导 在Slelz B细胞中观察到的指纹。 目的2.区分B细胞固有的和DC依赖的分子机制 其中SleSz可能参与了狼疮B细胞的激活。除了确定SleSz如何影响B细胞外 从本质上讲，我们还将阐明细胞和分子机制，这可能解释为什么 狼疮树突状细胞可能在帮助B细胞制造自身抗体方面做得更好。 目的3.确定B细胞对AKT轴或STATS(或其他轴， 在B6.Slelz.SleSz小鼠中发现的狼疮表型所必需的)。通过烧蚀或超- 以B细胞固有的方式表达这些分子，我们将确定这2个分子是如何激活的 B细胞途径可能参与了B6slelz.SleSz同源基因小鼠的狼疮发病。

Sle1 on murine chromosome 1 and SleS on murine chromosome 7 represent 2 of the strongest loci for lupus in the NZM2410 mouse model. Whereas normal (B6)mice engineered to have Sle1 alone exhibit mild lupus, normal mice engineered to bear both loci develop severe lupus. Hence, B6, B6.Sle1z and B6.Sle1z.Sle3z congenic strains capture 3 distinct stages of disease development in lupus, reminiscent of the stages seen in human lupus development. More recently, we have documented that B-cells in these mice exhibit a progressive activation of multiple signaling pathways, including the AKT/mTOR axis, various MARK pathways, NFkB, STATS and STATS, and various Bcl-2 family members, with the levels of activation correlating well with disease severity. We have also learned that the candidate gene for the strongestsub- locus within Slelz, SLAM/Ly108, functions in a B-cell intrinsic fashion to breach early B-cell tolerance. Though the culprit genes for SleSz remain unknown, it is apparent that SleSz impacts the function of DCs and B-cells intrinsically. Based on these observations, we propose 3 Aims. Aim 1. To ascertain if the signaling pathways upregulated in Slelz B-cells are the direct consequence of chronic stimulation by autoantigens and/or polymorphic differences between the normal and lupus- associated alleles/isoforms of Ly108. We will ascertain how chronic BCR stimulation, as well as the lupus- associated Ly108.1 and the "normal" Ly108.2 isoforms of Sle1b/SLAM, might contribute to the signaling fingerprints observed in Slelz B-cells. Aim 2. To distinguish between the B-cell intrinsic versus DC-dependent molecular mechanisms through which SleSz might contribute to B-cell activation in lupus. In addition to determining how SleSz affects B-cell signaling intrinsically, we will also elucidate the cellular and molecular mechanisms that may explain why lupus DCs may be better at "helping" B-cells makeautoantibodies. Aim 3. To ascertain the degree to which B-cell intrinsic activation of the AKT axis, or STATS (or other axes, where indicated) is necessary for the lupus phenotypes seen in B6.Slelz.SleSz mice. By ablating or hyper- expressing these molecules in a B-cell intrinsic fashion, we will ascertain how the activation of these 2 pathways in B-cells might contribute to lupus in B6.Slelz.SleSz congenic mice.