Novel Role of a Protein Phosphatase in Chromosome Segregation (360G-Wellcome-208908_Z_17_Z)

Kinases and their antagonistic phosphatases both provide a key regulatory mechanism controlling many cellular events. Yet our molecular understanding of phosphatases lags behind. Recently we described an interaction between Protein Phosphatase 4 (PP4) and Drosophila centromeres, which when disrupted affects the mitotic centromere integrity and spindle assembly checkpoint activity. The details of this pathway remain to be elucidated. Nor is it known how this finding relates to PP4's de-regulation in many cancers. I will therefore turn to human cell line model to address these questions. Towards determining human PP4’s mitotic functions, CRISPR/Cas9 gene editing will be used to generate cell lines expressing endogenous PP4 fused with the AID tag allowing for inducible and rapid degradation of the phosphatase. This approach will facilitate PP4 removal specifically in mitotic cells, the effects of which will be characterised by cell imaging. Parallel studies, including proteomics, will deliver precise information on the human PP4 interaction network and behaviour during mitosis. Together these data will reveal the affected processes and provide a blueprint for subsequent detailed investigations that identify the involved pathways, PP4-specific substrates and their phospho-regulatory sites. The results of this study will be later placed within a larger investigatory framework dissecting chromosome segregation.