LUPUS GENES AND B-CELL SIGNALING

描述（由申请人提供）：鼠1号染色体上的Sle 1和鼠7号染色体上的Sle 3代表NZM 2410小鼠模型中狼疮的2个最强基因座。为了了解这些基因座是如何导致狼疮的，这些疾病基因座已经被回交到相对正常的C57 BL/6背景上作为同源间隔。而B6小鼠是健康的，B6.Sle 1小鼠发展为轻度狼疮，B6.Sle 1.Sle 3双基因小鼠发展为重度狼疮性肾炎。我们最近已经证明，这些同源物中的成熟B细胞表现出多种信号传导途径的进行性激活，包括AKT/mTOR轴、各种MAPK途径、NFkB、STAT 3、STAT 5和各种Bcl-2家族成员，激活水平与疾病严重程度和易感基因剂量密切相关。重要的是，其中一些轴的激活，特别是NF κ B和STAT 3，在患有严重狼疮的双克隆小鼠中特别明显，但在B6.Sle 1小鼠中则不明显。目前尚不清楚这些信号通路的激活对于疾病来说是否是必要的或足够的。我们假设NFkB和STAT 3激活对于狼疮的发病机制至关重要。这将使用目标2中的遗传学方法和目标3中的药理学方法进行测试。虽然Sle 3的罪魁祸首基因仍然未知，但我们已经了解到Sle 1中最强子位点的候选基因，即SLAMF 6/Ly 108，以B细胞内在方式发挥作用，以破坏早期B细胞耐受性。目前，Ly 108可能破坏耐受性的分子机制仍不清楚。我们假设Ly 108的多态性变体可能通过在未成熟B细胞内参与不同的信号传导途径来破坏B细胞耐受性。这一假设将在目标1中得到检验。总的来说，这些研究对系统性红斑狼疮的机制起源以及如何治疗具有重要意义。公共卫生相关性：我们对细胞内哪些信号通路在狼疮的不同阶段最活跃还没有明确的认识。使用新的遗传简化的小鼠模型，拟议的研究旨在确定狼疮中不同细胞类型的精确分子贡献。这些研究还将确定狼疮淋巴细胞中激活的2种特定分子是否对疾病至关重要。使用这些新的遗传模型揭示狼疮发病机制中的重要节点可能为针对关键信号节点的狼疮更有效的治疗铺平道路。

DESCRIPTION (provided by applicant): Sle1 on murine chromosome 1 and Sle3 on murine chromosome 7 represent 2 of the strongest loci for lupus in the NZM2410 mouse model. To understand how these loci contribute to lupus, these disease loci have been backcrossed onto the relatively normal C57BL/6 background as congenic intervals. Whereas B6 mice are healthy, B6.Sle1 mice develop mild lupus, and B6.Sle1.Sle3 bicongenic mice develop severe lupus nephritis. We have recently documented that mature B-cells in these congenics exhibit progressive activation of multiple signaling pathways, including the AKT/mTOR axis, various MAPK pathways, NFkB, STAT3, STAT5, and various Bcl-2 family members, with the levels of activation correlating well with disease severity and susceptibility gene dosage. Importantly, the activation of some of these axes, notably NFkB and STAT3, were particularly pronounced in bicongenic mice with severe lupus, but not in B6.Sle1 mice. Whether the activation of any of these signaling pathways is necessary or sufficient for disease is not known. We hypothesize that NFkB and STAT3 activation is essential for the pathogenesis of lupus. This will be tested using a genetic approach in Aim 2 and a pharmacological approach in Aim 3. Though the culprit gene for Sle3 remains unknown, we have learned that the candidate gene for the strongest sub-locus within Sle1, namely SLAMF6/Ly108, functions in a B-cell intrinsic fashion to breach early B-cell tolerance. Presently, the molecular mechanisms through which Ly108 might breach tolerance remain unclear. We hypothesize that polymorphic variants of Ly108 may breach B- cell tolerance by engaging different signaling pathways within immature B-cells. This hypothesis will be tested in Aim 1. Collectively, these studies have important implications towards the mechanistic origins o systemi lupus erythematosus and how it is managed therapeutically. PUBLIC HEALTH RELEVANCE: We do not have a clear understanding of which signaling pathways within cells are most activated in different stages of lupus. Using novel genetically simplified mouse models, the proposed study aims to define the precise molecular contributions of different cell types in lupus. These studies will also ascertain if 2 particular molecules activated in lupus lymphocytes are essential for disease. Uncovering essential nodes in lupus pathogenesis using these novel genetic models are likely to pave the way towards more effective therapy in lupus targeting critical signaling nodes.