IDENTIFYING AND EXPLOITING POST-TRANSLATIONAL MODIFICATIONS IN ANTIGEN PRESENTATION USING NEXT GENERATION PROTEOMICS

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BackgroundIn previous BBSRC-funded work being advanced through this new collaboration between Durham, Liverpool and Scancell, we have identified novel routes for the presentation of antigens by MHC class II molecules (MHCII) to the immune system. MHCII display antigens to helper T cells to control infections by bacteria and other pathogens, but also present modified self-antigens (e.g. neoantigens). The Benham group has found that some MHCII types e.g. HLA-DP4, assemble independently of CD74, a protein that normally directs the MHCII to the endosomal system. These HLA-DP4 molecules can stably bind self- peptides in other compartments e.g. the Endoplasmic Reticulum and autophagic vesicles. Scancell/Durrant (amongst others) have shown that post-translationally modified (e.g. citrullinated) peptides can access these MHCII, generating novel modified peptides that can break self-tolerance and cause an immune response. This mechanism has implications for the control of infectious disease in humans and livestock, for the development of anti-cancer vaccines and for bespoke therapies for autoimmunity. Aims, Hypothesis and Experimental ApproachWe hypothesise that neoantigens can be accessed by HLA-DP4 during unconventional intracellular trafficking. The overarching aim of this project is to characterise these novel antigens and establish the cell biology that drives their display at the cell surface. Supporting this aim, we will employ underpinning mass spectrometry capability to define MHC combinatorial modifications by native ms, map the immuno-proteome with quantitative ms and identify post-translationally modified MHC peptides in two systems (reconstituted antigen presenting cells and a humanised mouse melanoma model developed by the CASE partner). The student will also be trained in a wide range of laboratory methods including confocal microscopy, tissue culture, SDS-PAGE/western blotting, biochemical/cellular assays, molecular biology, bioinformatics and statistical computing (R). The student will be trained in presentation skills and report writing, encouraged to present their work at international meetings, and will participate in a regular journal club. Relevance to BBSRC strategyThe project is both curiosity-led and creative, being catalysed by new developments in technological capability. The project sits broadly within the remit for world class underpinning Biosciences and relates directly to a systems approaches to the Biosciences and to technology development for the Biosciences, through the strong focus on advancing quantitative and mechanistic proteomic technologies.