How does atypical protein kinase C signalling regulate actomyosin-mediated force generation in polarised cells?

Epithelial cells are polarised, and the localisation of the polarity-driving PAR complex overlaps with that of actomyosin significantly. Actomyosin's roles in contractility and cell structure drive morphogenesis during development. The PAR complex effector atypical protein kinase C (aPKC) is linked to actomyosin regulation, yet the full scope of regulatory mechanisms is unclear. aPKC has also been implicated in disease contexts including neurodegeneration and cancer progression. I therefore propose an unbiased screen to identify novel aPKC substrates. Using an analogue-sensitive version of aPKC, substrates will be thiophosphorylated, purified, identified through mass spectrometry, and interactions with aPKC validated
in vitro. Hits will be investigated, with their normal localisation and localisation under acute aPKC inhibition characterised using fluorescence microscopy. Genetic approaches will also be used to elucidate mechanisms driving actomyosin regulation by aPKC. The Drosophila model system will allow analysis of different cell types, enabling the identification of context-dependent aPKC activity.