Mechanistic insight into DNGR1-mediated cross-presentation

C-type lectin receptors (CLRs) constitute a heterogeneous group of proteins that, in conjunction with Toll-like receptors (TLRs), Nod-like receptors (NLRs) and RIG-I like receptors (RLRs), function in innate and adaptive immunity. Many CLRs are expressed on the surface of myeloid cells and may bind pathogen-derived ligands, most commonly a carbohydrate structure on the outer membrane of bacteria, fungi or viruses. DNGR-1 (also named CLEC9A) is a recently identified CLR that is highly expressed by CD8alpha+-like dendritic cells (DCs), a DC subset that excels in cross-presentation. This transmembrane receptor is unusual in that it recognizes a self ligand exposed by necrotic cells and enhances cross-presentation of dead-cell-associated antigens to CD8+ T cells. The objective of this research proposal is to understand the mechanism by which DNGR-1 promotes cross-presentation of cell-associated antigens. I hypothesize that a conserved residue or post-translational modification unique to the intracellular tail of DNGR-1 regulates trafficking of DNGR-1 to a specialized endosomal compartment and/or promotes antigen translocation from endosomes to cytosol, allowing entry of dead cell-derived antigens into the major histocompatibility complex (MHC) class I processing pathway. Using a combination of biochemical, cell biological, and immunological approaches, I propose to unravel the mechanistic basis of DNGR-1-mediated cross-presentation.