Structural Studies of a T cell Specific Tyrosine Kinase

描述（由申请方提供）：酪氨酸激酶活性是细胞信号级联的关键组分。在信号传导过程中必须维持对激酶活性的精确调节控制，如蛋白激酶失调引起的许多人类疾病所证明的。该项目旨在从分子水平上了解酪氨酸激酶活性在T细胞信号传导过程中是如何调节的。目前的更新申请继续关注Tec家族免疫酪氨酸激酶白细胞介素-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的数据，支持ITK监管的机制模型。具体来说，我们已经确定了Itk二聚化作为一个开关，把Itk催化活性'关闭'，我们已经发现了一个特定的对接之间的相互作用Itk和它的基板，确保保真度在目标磷酸化，我们有数据表明，肽基脯氨酰异构酶，亲环素A，控制Itk的活动，通过防止基板对接。我们对Itk和相关Tec家族成员的研究也扩展了我们对酪氨酸激酶Src家族底物识别的理解。Src激酶Lck通过使Itk激酶结构域中的特定酪氨酸磷酸化而在TCR接合后激活Itk，并且我们现在已经确定该反应通过识别远程底物对接位点而发生。本申请中提出的目标将对所描述的所有蛋白质调节复合物进行详细的结构研究。从这项工作中产生的分子水平知识将提供对T细胞信号传导的更好理解，以及针对治疗用途的特定相互作用的方法。公共卫生相关性：该提案旨在了解导致免疫应答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，以限制或加强面对自身免疫、免疫抑制或免疫性疾病的免疫反应。特别是激酶是主要的治疗靶点，因为它们控制许多免疫细胞信号传导，并且特定激酶中的遗传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.