Proteome Profiling Of Phosphotyrosine-mediated Signaling And Functional Investigation Of Key Signaling Molecules

Phosphotyrosine signaling network is made up of many signaling cascades regulated by multiple protein complexes via tyrosine phosphorylation events on a multitude of associated proteins. Phosphotyrosine signaling network is also involved in many aspects of cellular functions, such as proliferation, differentiation, apoptosis, migration and cell polarity. Dysfunction of phosphotyrosine signaling network is tightly correlated with numerous diseases, such as cancer and diabetes. Each single and linear phosphotyrosine signal pathway has been extensively studied in the past 20 years, but the regulatory mechanism of the entire network is still poorly understood. Owing to the lack of effective means, the components and their regulatory roles of the nodes and cross-talk points are not well defined. To better understand the regulatory mechanism and the potential biological function of phosphotyrosine signaling network, and to explore novel and crucial nodes or cross-talk points of the network, we established and improved a powerful method combining phospho-proteomics and signal transduction to analyze the phosphotyrosine signaling network. Based on this strategy, we found a number of novel phosphotyrosine proteins and their associated proteins. In addition, we demonstrated the phosphotyrosine-dependent mechanism of Par3 in epithelial cell polarity formation, identified a novel gene PHF14 involved in cell cycle progression, and characterized the role of CASK in gene expression and glucose uptake induced by insulin. Our data provide novel nodes and cross-talk points between phosphotyrosine signaling and formation of epithelial cell polarity or regulation of cell cycle or modulation of glucose uptake, which pave the way of the functional study in phosphotyrosine signaling network.My work contains two major parts, proteome profiling of phosphotyrosine-mediated signaling (chapter 1) and novel function analysis of three key molecules: Par3, PHF14 and CASK. In order to better clarify the second part, it is divided into three chapters. The title of each chapter was listed as followed: tyrosine phosphorylated Par3 regulates epithelial tight junction assembly promoted by EGFR signaling (chapter 2); identification of a novel PHD finger protein 14 involved in cell cycle progression (chapter 3) and CASK regulates the expression of genes and glucose uptake induced by insulin (chapter 4).