Nonreceptor tyrosine kinases in Systemic Lupus Erythematosus

酪氨酸激酶是真核细胞生长、分化和凋亡的重要调节因子。 在许多癌症和炎症性疾病中观察到不适当的酪氨酸激酶信号转导。这 该项目的重点是AcK1和BRK非受体酪氨酸激酶的结构、活性和调节。 在与弗雷德里克·盖斯曼博士和同事的合作下，我们发现了一系列的损失- 重症系统性红斑狼疮患者AcK1和BRK基因功能突变的研究 (SLE)。这些是第一个被发现与这种疾病有关的酪氨酸激酶突变。我们的前期工作 显示突变显著降低(或完全阻断)激酶活性，下游信号转导， 以及对凋亡细胞的吞噬。我们建议对野生型和突变型进行功能研究 哺乳动物细胞中AcK1和BRK的形式，包括诱导多能干细胞(IPSC)的实验- 来自狼疮患者及其健康亲属的巨噬细胞。我们将在全球范围内进行 底物特异性，以确定突变是否“重新连接”细胞信号网络。我们还将 对纯化的突变激酶进行机制和结构研究，并测试它们是如何偶联的 与细胞表面受体MerTK结合。总体假设是AcK1和BRK链接识别 磷脂酰丝氨酸对凋亡细胞的吞噬作用。对该信号的调节或调整 通路为自身免疫性疾病的治疗提供了一种新的策略。

Tyrosine kinases are important regulators of growth, differentiation, and apoptosis in eukaryotic cells. Inappropriate tyrosine kinase signaling is observed in many cancers and inflammatory diseases. This project focuses on the structure, activity, and regulation of the Ack1 and Brk nonreceptor tyrosine kinases. In collaboration with Dr. Frederic Geissmann and colleagues, we have discovered a series of loss-of- function mutations in Ack1 and Brk in a cohort of patients with severe Systemic Lupus Erythematosus (SLE). These are the first tyrosine kinase mutations found to be linked to this disease. Our preliminary work shows that the mutations drastically decrease (or completely block) kinase activity, downstream signaling, and phagocytosis of apoptotic cells. We propose to conduct functional studies of the wild-type and mutant forms of Ack1 and Brk in mammalian cells, including experiments in induced pluripotent stem cell (iPSC)- derived macrophages from the lupus patients and their healthy relatives. We will carry out global screens of substrate specificity to determine whether the mutations “rewire” cellular signaling networks. We will also carry out mechanistic and structural studies on the purified mutant kinases, and test how they are coupled to the cell surface receptor MerTK. The overall hypothesis is that Ack1 and Brk link recognition of phosphatidylserine on apoptotic cells to phagocytic engulfment. Regulation or tuning of this signaling pathway could provide a new strategy for therapeutic approaches in autoimmune diseases.