Characterisation of the ribosome generating peptides for major histocompatibility class I tolerance from pre-spliced mRNAs – PepTol

The proposal is based on strong preliminary data showing that translation of pre-spliced mRNAs generates peptides for immune tolerance for the major histocompatibility (MHC) class I pathway. We have introduced an antigenic peptide sequence (SL8 from chicken ovalbumin (Ova)) in the second intron of the B-globin gene in a C57BL/6 mouse (HBB) and can show that the animals are immune tolerant towards this epitope (Figure 1). We now propose to characterize the ribosome responsible for this non-canonical event translating pre-spliced mRNAs (see figure 2) and understand how it is regulated. This will have a major impact on i) understanding the immunological properties of mRNAs and give a better understanding of how the immune system is activated against RNA vaccines and explain the origin of intron-derived peptides presented on MHC class I molecules. This will ii) pave the way for controlling the production of antigenic peptide substrates for the MHC class I pathway and have implications for regulating the expression of antigens in autoimmune and cancer diseases. The outcome of this project will iii) describe a novel mRNA translation event that will help explain the physiological role of a previously demonstrated large pool of non-AUG initiated translation products (Ingolia et al., 2009).
We propose to characterize the ribosome responsible for translating pre-spliced mRNAs and how this event is regulated. The long term aim is to shed light on this non-canonical translation event and identify means by which the synthesis of MHC class I substrates can be manipulated. This will have important implication for designing vaccines and for understanding aspects of cancer immune evasion as well as autoimmune diseases.