Mapping the IMiD-dependent cereblon interactome using BioID-proximity labelling

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Immunomodulatory imide drugs (IMiDs) are crucial for multiple myeloma (MM) therapy.
• IMiDs function by binding cereblon (CRBN), an E3 ligase adaptor, altering substrate specificity and degrading key MM transcription factors.
• Understanding IMiD toxicities requires deeper mechanistic insight beyond therapeutic targets.

Purpose of the Study:

• To characterize the CRBN interactome using BioID2-dependent proximity labeling (BioID2-CRBN) in the presence and absence of IMiDs and bortezomib.
• To identify novel CRBN interactions and potential contributors to IMiD-associated toxicities.
• To establish proximity labeling as a tool for mechanistic profiling of E3 ligase-modulating drugs.

Main Methods:

• Utilized BioID2-CRBN proximity labeling to map protein interactions with CRBN.
• Analyzed CRBN interactome changes induced by IMiDs and the proteasome inhibitor bortezomib in MM cells.
• Identified biotinylated proteins and characterized novel CRBN-protein interactions.

Main Results:

• BioID2-CRBN successfully biotinylated known CRBN interactors and neosubstrates upon IMiD treatment.
• Bortezomib alone significantly altered the CRBN interactome.
• Identified 'neointeractors'—proteins augmented in interaction with CRBN by IMiDs but not degraded—distinct from neosubstrates.
• Discovered Non-Muscle Myosin Heavy Chain IIA (MYH9) as a putative CRBN neointeractor.

Conclusions:

• Proximity labeling with BioID2-CRBN provides a powerful approach to map drug-induced changes in E3 ligase interactomes.
• MYH9 is identified as a novel CRBN neointeractor potentially contributing to IMiD-related hematological toxicities.
• These findings advance the mechanistic understanding of IMiD action and toxicity, paving the way for improved therapeutic strategies.