The human body comprises trillions of meticulously organised cells with specific regulatory mechanisms to establish correct tissue architecture and maintain homeostasis. One such core mechanism is Cell Polarity, a fundamental process in all invertebrate and vertebrate cells that dictates the asymmetric organisation of cellular components to define distinct structures and functions. Loss of cell polarity disrupts tissue homeostasis and is considered one of the earliest hallmarks of cancer.
The evolutionarily conserved Scribble protein is a key regulator of cell polarity and known tumour suppressor. Acting as an adaptor protein, Scribble facilitates protein-protein interactions at distinct subcellular localisations, coordinating a range of processes from wound healing and immune response to learning and memory. Scribble achieves this by virtue of its multi-domain structure and spatially restricted basolateral membrane localisation. Consequently, Scribble’s mislocalisation is implicated in the development of aggressive epithelial cancers and lethal neural tube defects in human patients. Despite increasing knowledge on Scribble, the precise mechanism by which its mislocalisation plays a role in disease remains unclear.
I hypothesise that alterations in the spatiotemporal protein interaction network of mislocalised Scribble contributes to its pathological properties. Using the live-cell proximity-labelling technique, APEX2, combined with proteomic analysis of Scribble’s interacting PDZ domains, I aim to map the differential surrounding protein network of mislocalised Scribble. Using the above proteomic approaches together with complementary cellular structure function studies, I have identified novel Scribble-interacting proteins in a normal setting, as well as a potential loss of known interaction partners in patient-derived mutant alleles. This data forms the start of a larger scale characterisation of mislocalised Scribble’s interaction network, and the downstream effect this has on Scribble’s function in a disease setting.