Research
Ubiquitin ligases are enzymes that decorate proteins in the cell with ubiquitin, a relatively large (76aa) peptide. This modification with ubiquitin on a protein can signal many different things to the target substrate, A well-described effect brought about by ubiquitination is that it changes a protein's stability, but other effects include changes to localisation, intracellular trafficking, binding partners, and function. My laboratory is particularly intrigued by these 'alternate' ubiquitin-mediated signals. We are also interested in ubiquitin signalling within different cellular contexts, as we have discovered ubiquitin networks vary from tissue to tissue and use mouse models to study the molecular basis for this. We want to understand the dynamic nature and complexity of ubiquitin signalling, and invent novel therapeutics exploiting ubiquitin ligase enzymology and their critically regulated pathways.
H&E staining of spleen sections from mice deficient in expression of Fbxo7.
The biology of Fbxo7/PARK15: from anaemia to cancer to Parkinson's disease.
In 1997, we cloned the F-box protein, Fbxo7, as an interacting partner for a herpesvirus-encoded viral cyclin. We have since created multiple mouse models that are deficient in the expression of Fbxo7 either in the whole mouse or in specific tissues. We investigate the numerous disease, including anaemia and cancer, seen in multiple tissues, ranging from both B and T lymphocytes to red blood cells. In 2008. mutations in Fbxo7 were discovered to be associated with idiopathic and early onset forms of Parkinson's disease. We also investigate the loss of its expression in dopaminergic neurons, the cells that are lost in this disease. We are investigating the molecular basis for the different pathways regulated by Fbxo7 that cause these pathologies in various cell types.
Engineering better protein interactions using the diversity of the immune system (A) or structurally informed, conformationally constrained peptides (B).
Targeting ubiquitin ligases and ubiquitinated proteins with novel biotherapeutic approaches.
The discovery of camelid-derived antibodies known as nanobodies offers researchers all the specificity and affinities of conventional antibodies in a compact, highly-stable domain, known as a nanobody. We use nanobodies to define and test the functional significance of interactions between ubiquitin ligases and their substrates. We collaborate with Serge Muyldermans to produce nanobodies.
We also are investigating the possibility of specifically interfering with the capacity of ubiquitin ligases to modify their substrates. Based on structural information, we collaborate with Laura Itzhaki and David Spring in the production of stapled peptides that mimic the conformation of docked substrates in ubiquitin ligases and test the biochemical and cellular effects of stapled peptides on the ubiquitin ligases.
Purified active SCF-ligases used on protein arrays to identify networks of ubiquitinated substrates.
Deregulated SCF networks in epithelial cancers.
We are investigating the consequences of the rearrangement of two F-box genes in breast cancer. We are doing a biochemical analysis of the effect of the mutations on the ligases and on the pathways that they regulate using proteome wide approaches, including protein arrays, mass spectrometry, and yeast two hybrid screens. Specific substrates and the critical pathways that are deregulated are being defined, and their role in oncogeneisis studied.
