Function and Modulation of USP11 in Cancer

The modification of substrate proteins by ubiquitination is a crucial mechanism for regulating the activity and levels of proteins in eukaryotes. Therefore, interference with the ubiquitin system offers valuable avenues for modulating cellular protein function and degradation impacting on protein levels with applications in basic research, drug development and biotechnological applications.
The main aim of this project is the identification and evaluation of ubiquitin specific protease modulators that alter ubiquitin-mediated protein degradation pathways. Ubiquitin specific proteases (USPs) can salvage proteins from destruction by the proteasome by reversing ubiquitination. USP11 associates with homologous recombination proteins and is a key regulator of DNA damage repair reversing ubiquitination of several proteins critical to cellular function such as p21, histones, senataxin and p53. In addition, USP11 also regulates autophagy and contributes to proteotoxicity, the innate immune response and inflammation. Depletion or silencing of USP11 has been shown to be effective in targeting DNA damage response (DDR) pathway deficient tumours, killing clinically relevant platinum-resistant cancer cells and can inhibit pancreatic cancer cell survival.
In previous studies we identified a novel peptide binder of USP11 that interacted with a novel site in the N-terminal region and differentially affected survival of a panel of cell lines. In this project, we will further probe the function of this novel binding site in USP11 and conduct fluorescence polarization assays to identify novel inhibitors from an in-house compound collection. Structural biology techniques including X-ray crystallography or cryo-electron microscopy will characterise structures of USP11-inhibitor complexes to gain insight into the interactions and together with binding assays investigate the specificity of identified inhibitors. The top scoring inhibitors will be evaluated in cellular assays probing the impact on protein levels of USP11 substrates and cell viability using pancreatic cancer cells as model system.
Together, this interdisciplinary project offers skill development in protein biochemistry, fluorescence assays, structural biology and cell biology and will advance our understanding of USP11 function, structure and inhibition and create novel tools for the manipulation ubiquitination to ultimately target cancer cells.