PROTAC-driven Protein degradation by Proteasome during Antigen Processing and Presentation (ProAPP)

PROteolysis TArgeting Chimera (PROTAC) is a new and attractive therapeutic approach that regulates a target protein by channeling it to the proteasome for degradation (an energy-demanding pathway). Concurrently, proteasomes also play a central role in generating the peptide repertoire for antigen presentation on the Human Leukocyte Antigen-I (HLA-I) molecules. A few years after PROTAC was invented, proteasomes were found to catalyze not only canonical peptide bond hydrolysis, but are also capable of “cut-and-paste” events, i.e. generating spliced peptides, which have been shown to be frequently presented n HLA-I immunopeptidomes. It is unclear how PROTAC-driven proteasome degradation modulates the spliced and non-spliced peptide repertoire derived from a targeted protein. Alterations in peptide variety and quantity produced by proteasome may lead to strong implications on the HLA-I immunopeptidome, and, hence, could result in immune implications. Therefore, using the key oncoprotein KRAS as a PROTAC’s target, this study intends to understand: (i) how PROTAC-driven KRAS degradation affects cellular pathways on a system-wide level; (ii) the impact of PROTAC on KRAS derived peptide repertoire generated by proteasomes; (iii) to what extent PROTAC enhances KRAS derived peptide presentation on HLA-I molecules. Through the combination of a multidisciplinary approach; molecular biology, biochemistry, proteomics, bioinformatics and cellular immunology, this study will provide a better fundamental understanding of the effect of PROTAC-KRAS on the cellular proteome, proteasome-derived peptide repertoire (spliced and non-spliced peptides) and HLA-I immunopeptidome landscape, thus, provide insights into the suitability of PROTAC-KRAS application as a therapeutic approach for anti-cancer therapies. Additionally, this project will deepen our understanding of the role of spliced peptides in the antigen processing and presentation pathway.