Mechanisms of target cell entry and applications of protein toxinx. (360G-Wellcome-080566_Z_06_Z)

Ricin and Shiga(-like) toxin catalyse a depurination of eukaryotic ribosomes to promote cell death. To target ribosomes, these proteins undergo retrograde transport to the endoplasmic reticulum (ER) before retrotranslocating its membrane. The current model suggests they accomplish this by exploiting, but then uncoupling from, the ER-associated degradation pathway - a quality control system that detects and delivers aberrant ER proteins to the cytosol for proteasomal degradation. However, this model is by no means proven and molecular details of all downstream steps of the cellular intoxication process for these toxins remain scant. As examples of non classical ERAD and ribosome-tethered chaperones begin to emerge, one goal of this application is to characterise toxin-ER membrane interactions, and toxin retro-translocation and fate in the cytosol. A second goal is to optimise vaccination protocols based on using inactive ricin A chain fused with antigenic peptides/proteins in an approach involving delivery into dendritic cells and intersection of the MHC class I presentation pathway. Different dendritic cell maturation protocols will also be compared to ensure optimal priming of antigen-specific T and B cell responses. This will provide a general platform for the design of effective T cell therapy against cancer and infectious diseases and may be appropriate for the ongoing development of an effective anti-ricin vaccine.