Mayya Viveka, Lundgren Deborah H, Hwang Sun-Il, Rezaul Karim, Wu Linfeng, Eng Jimmy K, Rodionov Vladimir, Han David K
Department of Cell Biology, University of Connecticut Health Center, Farmington, 06030, USA.
Sci Signal. 2009 Aug 18;2(84):ra46. doi: 10.1126/scisignal.2000007.
Protein phosphorylation events during T cell receptor (TCR) signaling control the formation of complexes among proteins proximal to the TCR, the activation of kinase cascades, and the activation of transcription factors; however, the mode and extent of the influence of phosphorylation in coordinating the diverse phenomena associated with T cell activation are unclear. Therefore, we used the human Jurkat T cell leukemia cell line as a model system and performed large-scale quantitative phosphoproteomic analyses of TCR signaling. We identified 10,665 unique phosphorylation sites, of which 696 showed TCR-responsive changes. In addition, we analyzed broad trends in phosphorylation data sets to uncover underlying mechanisms associated with T cell activation. We found that, upon stimulation of the TCR, phosphorylation events extensively targeted protein modules involved in all of the salient phenomena associated with T cell activation: patterning of surface proteins, endocytosis of the TCR, formation of the F-actin cup, inside-out activation of integrins, polarization of microtubules, production of cytokines, and alternative splicing of messenger RNA. Further, case-by-case analysis of TCR-responsive phosphorylation sites on proteins belonging to relevant functional modules together with network analysis allowed us to deduce that serine-threonine (S-T) phosphorylation modulated protein-protein interactions (PPIs) in a system-wide fashion. We also provide experimental support for this inference by showing that phosphorylation of tubulin on six distinct serine residues abrogated PPIs during the assembly of microtubules. We propose that modulation of PPIs by stimulus-dependent changes in S-T phosphorylation state is a widespread phenomenon applicable to many other signaling systems.
T细胞受体（TCR）信号传导过程中的蛋白质磷酸化事件控制着TCR近端蛋白质之间复合物的形成、激酶级联反应的激活以及转录因子的激活；然而，磷酸化在协调与T细胞激活相关的各种现象中的影响方式和程度尚不清楚。因此，我们使用人类Jurkat T细胞白血病细胞系作为模型系统，对TCR信号传导进行了大规模定量磷酸化蛋白质组学分析。我们鉴定出10665个独特的磷酸化位点，其中696个显示出TCR反应性变化。此外，我们分析了磷酸化数据集的广泛趋势，以揭示与T细胞激活相关的潜在机制。我们发现，在TCR刺激后，磷酸化事件广泛靶向参与与T细胞激活相关的所有显著现象的蛋白质模块：表面蛋白的模式化、TCR的内吞作用、F-肌动蛋白杯的形成、整合素的外向内激活、微管的极化、细胞因子的产生以及信使RNA的可变剪接。此外，对属于相关功能模块的蛋白质上的TCR反应性磷酸化位点进行逐个分析，并结合网络分析，使我们能够推断丝氨酸-苏氨酸（S-T）磷酸化以全系统的方式调节蛋白质-蛋白质相互作用（PPI）。我们还通过显示微管蛋白在六个不同丝氨酸残基上的磷酸化在微管组装过程中消除了PPI，为这一推断提供了实验支持。我们提出，S-T磷酸化状态的刺激依赖性变化对PPI的调节是一种广泛存在的现象，适用于许多其他信号系统。
