Functional Analysis of Tyrosine Phosphatases in Cytoskeletal Regulation and Virus Spread

Phosphotyrosine-based signal transduction is fundamental to cell growth, migration and communication. Aberrant phosphotyrosine signalling, by dysregulation of pathways or subversion by pathogens, is implicated in a variety of human diseases. While such signalling requires a balance between kinase and phosphatase activities, research in this area has thus far heavily focused on tyrosine kinases. Tyrosine phosphatases, a large and heterogenous superfamily of proteins, are relatively understudied and our knowledge of their in vivo functions, interactors and mechanisms of action is highly limited. Using Vaccinia virus that hijacks host phosphotyrosine signalling to the cytoskeleton, I have identified three tyrosine phosphatases that regulate actin polymerisation. Here I propose to deeply characterise these model phosphatases using a combination of quantitative microscopy, protein interaction analyses and powerful C. elegans genetics. I will identify their binding partners and substrate-interaction motifs in healthy and virus- infected mammalian cells. I will measure the quantitative impact of these phosphatases on signalling dynamics using Vaccinia virus as a platform. Finally, I will determine their roles and localisation in a live organism. My research will generate fresh knowledge on how cellular tyrosine phosphatases perform their functions, paving roads for new therapeutic approaches in viral infections, cancers and more.