Novel role of a protein phosphatase in chromosome segregation

Kinases and their antagonistic phosphatases both provide a key regulatory mechanism that controls many cellular events. We do not fully understand the way phosphatases work at a molecular level but we have identified an interaction between protein phosphatase 4 (PP4) and Drosophila centromeres, which when disrupted affects the mitotic centromere integrity and activity at the spindle assembly checkpoint. This pathway remains to be elucidated along with its relation to PP4's deregulation in many cancers.

I will determine PP4’s mitotic functions in humans using CRISPR/Cas9 gene editing to generate cell lines expressing endogenous PP4 fused with the auxin-inducible degron (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.

This study 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 part of a larger investigation framework for chromosome segregation.