NEW TECHNOLOGIES FOR PHOTOCATALYTIC PROXIMITY LABELING AND THE APPLICATION THEREOF TO STUDY IMID MECHANISM OF ACTION

Abstract

μMap is a proximity labeling platform that leverages photocatalytic activation of diazirines to enable high-resolution mapping of protein interactomes. This dissertation describes the technological expansion and biological application of μMap in novel contexts. In Chapter 2, a high-resolution photocatalyst-based proximity labeling technology using red light is disclosed. This platform is demonstrated through the identification of protein interactions in whole blood and will ultimately enable high- resolution photocatalytic proximity labeling in whole tissues and live animals. In Chapter 3, μMap is utilized to explore how IMiDs, a class of molecules prescribed for treating multiple myeloma malignancies, perturb the endogenous microenvironment of their protein target, Cereblon (CRBN). Using μMap, we discover novel endogenous interactors of CRBN and uncover a new mechanism of action for IMiDs as protein-protein interaction inhibitors of CRBN function. Contrary to CRBN’s role as an E3 ligase adaptor for directing ubiquitination and degradation of proteins, IMiD-mediated displacement between CRBN and the novel endogenous interactors results in their destabilization. This mechanism is distinct from the ability of IMiDs to induce targeted protein degradation of IKZF1 and IKZF3 and could potentially explain the diverse phenotypes observed in IMiD-treated patients.