Structural Studies of a T cell Specific Tyrosine Kinase

描述(由申请人提供)：酪氨酸激酶活性是细胞信号级联反应的重要组成部分。在信号传递过程中，必须保持对蛋白激酶活性的精确调控，这在许多人类疾病中得到了证明，这些疾病都是由于蛋白激酶的失调而引起的。这个项目的目的是在分子水平上理解酪氨酸激酶活性是如何在T细胞信号转导过程中被调节的。目前的更新应用继续集中在Tec家族免疫性酪氨酸激酶，白介素2酪氨酸激酶，ITK。我们在过去一段时间的工作已经产生了初步数据，支持ITK监管的机械模型。具体地说，我们已经确定ITK二聚是关闭ITK催化活性的开关；我们已经发现ITK与其底物之间的特定对接相互作用，确保了靶向磷酸化的保真度；我们有数据表明，肽基脯氨酰异构酶，亲环素A，通过阻止底物对接来控制ITK的活性。我们对ITK和相关Tec家族成员的研究也扩大了我们对酪氨酸激酶Src家族底物识别的理解。在TCR参与后，Src激酶Lck通过磷酸化ITK激酶结构域中的特定酪氨酸来激活ITK，我们现在已经确定这一反应是通过识别远程底物对接位置而发生的。本申请中提出的目标将对所描述的所有蛋白质调节复合体进行详细的结构研究。从这项工作中出现的分子水平的知识将提供对T细胞信号的更好的理解，以及针对治疗用途的特定相互作用的手段。公共卫生相关性：这项建议旨在了解导致免疫反应中酪氨酸激酶激活的特定蛋白质相互作用。该项目的公共卫生相关性涉及开发新的方法，以限制或增强面对自身免疫、免疫抑制或免疫疾病的免疫反应。尤其是激酶是主要的治疗靶点，因为它们控制着大部分免疫细胞信号，而特定激酶的基因缺陷与特定的人类疾病有关。

DESCRIPTION (provided by applicant): Tyrosine kinase activity is a crucial component of cellular signaling cascades. Precise regulatory control over kinase activity must be maintained during signaling as evidenced by numerous human diseases that arise upon dysregulation of protein kinases. This project is aimed at generating a molecular level understanding of how tyrosine kinase activity is regulated during T cell signaling. The current renewal application continues to focus on the Tec family immunological tyrosine kinase Interleukin-2 tyrosine kinase, Itk. Our work over the last period has generated preliminary data that support mechanistic models for Itk regulation. Specifically, we have identified Itk dimerization as a switch for turning Itk catalytic activity 'off'; we have discovered a specific docking interaction between Itk and its substrates that ensures fidelity in target phosphorylation; and we have data that suggest that the peptidyl prolyl isomerase, cyclophilin A, controls Itk activity by preventing substrate docking. Our studies on Itk and related Tec family members have also extended our understanding of substrate recognition for the well studied Src family of tyrosine kinases. The Src kinase, Lck, activates Itk following TCR engagement by phosphorylating a specific tyrosine in the Itk kinase domain and we have now identified that this reaction occurs via recognition of a remote substrate docking site. The aims proposed in this application will pursue detailed structural studies of all of the protein regulatory complexes described. The molecular level knowledge that will emerge from this work will provide a better understanding of T cell signaling and the means to target specific interactions for therapeutic uses. PUBLIC HEALTH RELEVANCE: This proposal aims to understand specific protein interaction leading to activation of tyrosine kinases in the immune response. The public health relevance of the project relates to developing new ways to either limit or enhance the immune response in the face of autoimmunity, immunosuppression or immunological diseases. Kinases in particular are prime therapeutic targets since they control much of immune cell signaling and genetic defects in specific kinases are linked to specific human diseases.