Genetic and Biochemical Approaches to Tyrosine Kinase Fu

我们的实验室研究酪氨酸磷酸化和非受体酪氨酸激酶的信号转导，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进展的异常生长和发育。结合小鼠遗传学、细胞生物学和蛋白质生物化学，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途径来开发治疗影响这些系统的疾病的方法。近年来，我们的工作主要集中在Tec酪氨酸激酶家族的研究上，该家族的典型成员Btk是B细胞正常功能所必需的。Btk的突变是人类遗传疾病x连锁无核球蛋白症的原因。我们之前已经证明，在T细胞中表达的Tec家族激酶的突变可以严重损害小鼠T淋巴细胞的功能，从而首次确立了这些激酶在T细胞介导的免疫应答中的作用。在过去的一年里，我们的工作集中在这些激酶如何参与辅助性T细胞分化的信号通路，T细胞分化是免疫反应的关键调节成分，有助于确定个体是否产生细胞（Th1）或基于抗体（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。我们的研究结果表明，TCR反应的损伤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，我们开始研究其他可能参与T辅助细胞分化的信号分子，包括SAP，它在遗传疾病x连锁增殖综合征（XLP）中发生突变。在去年，我们培育了SAP缺陷小鼠。SAP缺陷小鼠的淋巴细胞发育正常，但在感染因子的攻击下，重现了XLP的特征，包括T细胞活化和IFN-g产生增加，抗体产生减少。未感染SAP小鼠的脾细胞产生增加的IFN-g和减少的IL-4，表明这些动物偏向Th1表型。我们的研究结果表明，辅助性T细胞的失调可能导致与（XLP）相关的表型。

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).