Genetic and Biochemical Approaches to Tyrosine Kinase Fu

我们的实验室研究涉及酪氨酸磷酸化和非受体酪氨酸激酶的信号转导，这些分子是参与正常细胞生长和分化的细胞内信号通路所需的分子，以及参与癌症形成和发展的异常生长和发育。利用小鼠遗传学、细胞生物学和蛋白质生物化学的结合，我们的工作集中在这些分子如何促进免疫系统和骨骼系统细胞的正常功能。通过这些研究，我们希望了解如何利用这些通路的操纵来开发影响这些系统的疾病的治疗方法。近年来，我们的工作集中在对酪氨酸激酶Tec家族的研究上，该家族的原型成员BTK是B细胞正常功能所必需的。BTK的突变是人类遗传性疾病X连锁无丙种球蛋白血症的原因。我们先前已经证明，在T细胞中表达的Tec家族激酶的突变可以严重损害小鼠的T淋巴细胞功能，从而首次确立了这些激酶在T细胞介导的免疫反应中的作用。在过去的一年里，我们的工作集中在这些激酶如何参与T辅助细胞分化所涉及的信号通路，T辅助细胞分化是免疫反应的一个关键调节成分，有助于确定一个人是基于细胞(Th1)还是基于抗体(Th2)的免疫反应。我们发现Tec激酶的突变可以改变参与Th2、CD4+T辅助细胞分化的转录因子的激活和抑制。我们的结果表明，TCR反应的损害不仅可能降低动物对抗原的反应能力，还可能改变所产生的免疫反应的类型。作为这些研究的延伸，我们开始检查其他可能参与T辅助细胞分化的信号分子，包括SAP，它在遗传性疾病X连锁增殖综合征(XLP)中发生突变。在过去的一年里，我们产生了SAP缺陷的小鼠。SAP缺陷小鼠有正常的淋巴细胞发育，但在感染病原体攻击后，XLP的特征重现，包括T细胞活化和干扰素-g的产生增加，抗体产生减少。来自未感染SAP小鼠的脾细胞产生增加的干扰素-g和降低的IL-4，这表明这些动物向Th1表型倾斜。我们的结果提示，辅助性T细胞调节失调可能与XLP相关的表型有关。

Our laboratory studies signal transduction involving tyrosine phosphorylation and non-receptor tyrosine kinases, molecules required for intracellular signaling pathways involved in normal cellular growth and differentiation as well as the abnormal growth and development involved in the formation and progression of cancer. Using a combination of mouse genetics, cell biology and protein biochemistry, our work has concentrated on how these molecules contribute to normal function of cells of the immune system and the skeletal system. Through these studies we hope to understand how manipulation of these pathways can be utlilized to develop therapeutics for diseases affecting these systems. In recent years our work has concentrated on studies of the Tec family of tyrosine kinases, the prototypical member of which, Btk, is required for normal function of B cells. Mutation of Btk is responsible for the human genetic disorder X-linked agammmaglobulimemia. We have previously shown that mutation of Tec family kinases expressed in T cells can severely impair T lymphocyte function in mice, thereby establishing for the first time a role for these kinases in T cell mediated immune responses. In the last year our work has concentrated on how these kinases participate in the signaling pathways involved in T helper cell differentiation, a critical regulatory component of immune responses that helps determine whether an individual mounts a cellular (Th1) or antibody based, (Th2) immune response. We have found that mutation of Tec kinases can alter activation and repression of transcription factors involved in Th2 CD4+ T helper cell differentiation. Our results suggest that impairment of TCR responses may not only reduce the ability of an animal to respond to antigen, but may also alter the type of immune response generated. As an extension of these studies, we began examining other signaling molecules potentially involved in T helper cell differentiation including SAP, which is mutated in the genetic disorder X-linked proliferative syndrome (XLP). In this last year we have generated mice deficient in SAP. SAP-deficient mice had normal lymphocyte development, but upon challenge with infectious agents, recapitulated features of XLP, including increased T cell activation and IFN-g production, and decreased antibody production. Splenocytes from uninfected SAP- mice produced increased IFN-g and decreased IL-4, suggesting a skewing of these animals to a Th1 phenotype. Our results suggest that T helper cell misregulation may contribute to phenotypes associated with (XLP).