Systematic Analysis of Protein-Protein Interactions Between the ErbB Family of RTKs and a Complete Set of Human Phosphatases

This thesis has created a resource describing interactions between the ErbB family receptor tyrosine kinases and human phosphatases using the Membrane Yeast Two Hybrid system (MYTH). A total of 55 phosphatases form 109 unique interactions between active and inactive (via peptide chain mutations) ErbB family members. The 29 interactors of ErbB2 were chosen for further study based on their rates of mutations across various cancer studies reported on CBioPortal. PTPRB, TPTE2, TNS3, EYA1, and SSH1 had the highest incidences of mutation and were analyzed for their effect on ERK1/2 phosphorylation when over-expressed in a mammalian system. While PTPRB could not be stably expressed in the system, the four other phosphatases all exhibited deregulated ERK1/2 phosphorylation. TPTE2 overexpression showed a decrease in ERK1/2 phosphorylation time, as did SSH1, which also lowered maximum ERK1/2 phosphorylation. TNS3 over-expression delayed the onset of ERK1/2 phosphorylation, while EYA1 lowered the maximum level of phosphorylation. This thesis highlights new potential players in ErbB family and signaling regulation.M.Sc