Dynamic Protein Palmitoylation in Cell Signaling

 描述（由申请人提供）：尽管蛋白质S-棕榈酰化在30多年前被发现，并且棕榈酰化蛋白质与包括癌症、心血管和免疫疾病在内的多种疾病的发病机制有关，但它仍然是研究最少的翻译后蛋白质修饰之一。高不稳定性是蛋白质棕榈酰化的关键特征之一，沿着其对蛋白质功能的显著影响，使其成为细胞内信号调节的一种有吸引力的机制。特别是， 蛋白质棕榈酰化可以通过将质膜定位的信号蛋白靶向到特定的质膜亚结构域来为质膜定位的信号蛋白的活化提供分子基础。已经确定，T细胞受体（TCR）信号传导途径的活化关键依赖于信号传导蛋白的棕榈酰化及其以棕榈酰化依赖性方式与液体有序质膜亚结构域（“脂筏”）的功能性缔合。然而，调节T细胞信号蛋白棕榈酰化和脂筏分配的分子机制在很大程度上仍然未知。在我们的初步实验中，我们发现TCR复合物的生理相关刺激导致酪氨酸激酶Lck的棕榈酰化的快速增加，这在TCR参与后几分钟内可检测到。为了解释这一发现，我们提出了一个模型，其中TCR复合物招募和激活质膜相关棕榈酰酰基转移酶（PAT），以增加棕榈酰化和质膜区室化的T细胞信号蛋白。我们将在两个具体目标中研究这一假设。在目标1中，我们将确定快速刺激依赖性蛋白棕榈酰化在TCR信号通路激活中的作用。我们将分析Lck，LAT和TCR信号通路的其他成员的刺激依赖性棕榈酰化的动力学和调节。在目标2中，我们将确定质膜定位的PAT是否介导T细胞活化。这一目标将潜在地揭示DHHC PAT在调节T细胞信号传导中的先前未表征的作用。总体而言，我们预计，实施一类新的调节酶进入经典的TCR信号通路将大大扩大与改变T细胞稳态相关的疾病的潜在治疗靶点的范围。

 DESCRIPTION (provided by applicant): Although protein S-palmitoylation was discovered more than 30 years ago and palmitoylated proteins have been implicated in pathogenesis of several diseases including cancer, cardiovascular and immune disorders, it remains one of the most understudied post-translational protein modifications. High lability, one of the key features of protein palmitoylation, along with its prominent effect on the protein function makes it an attractive mechanism for the regulation of intracellular signaling. In particular, rapid changes in protein palmitoylation could provide a molecular basis for activation of the plasma membrane-localized signaling proteins by targeting them into specific plasma membrane subdomains. It has been established that activation of the T cell receptor (TCR) signaling pathway is critically dependent on palmitoylation of signaling proteins and their functional association with the liquid ordered plasma membrane subdomains ("lipid rafts") in a palmitoylation-dependent manner. However, molecular mechanisms regulating T cell signaling protein palmitoylation and lipid raft partitioning remain largely unknown. In our preliminary experiments we found that physiologically relevant stimulation of the TCR complex leads to rapid increase in palmitoylation of the tyrosine kinase Lck which is detectable within minutes upon engagement of TCR. To interpret this finding, we propose a model in which the TCR complex recruits and activates plasma membrane associated palmitoyl acyltransferases (PATs) to increase palmitoylation and plasma membrane compartmentalization of T cell signaling proteins. We will investigate this hypothesis in two Specific Aims. In Aim 1 we will determine the role of rapid stimulus-dependent protein palmitoylation in activation of the TCR signaling pathway. We will analyze the dynamics and regulation of stimulus-dependent palmitoylation of Lck, LAT and other members of the TCR signaling pathway. In Aim 2 we will determine if plasma membrane-localized PATs mediate T cell activation. This Aim will potentially uncover a previously uncharacterized role of DHHC PATs in regulation of T cell signaling. Overall, we expect that implementation of a novel class of regulatory enzymes into the canonical TCR signaling pathway would greatly expand a range of potential therapeutic targets for diseases associated with altered T cell homeostasis.