Drug Target Strategies

Targeting the DCN1-UBC12 Protein-Protein Interaction in the Neddylation Activation Complex

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  Shaomeng Wang, PhD

  Warner-Lambert/Parke-Davis Professor in Medicine
  University of Michigan

The Cullin-RING E3 ubiquitin ligases (CRLs) regulate homeostasis of approximately 20% of cellular proteins and their activation require neddylation of their cullin subunit. Cullin neddylation is modulated by a scaffolding DCN protein through interactions with both the cullin protein and an E2 enzyme such as UBC12. Here we report the discovery of high-affinity, cell-permeable small molecule inhibitors of the DCN1-UBC12 interaction. Using these small-molecule inhibitors as chemical probes, we have made a surprising discovery that the DCN1-UBC12 protein-protein interaction is much more important for the neddylation of cullin 3 over other cullin family members. Treatment of cells of different tissue types with these potent DCN1 inhibitors selectively convert cellular cullin 3 into a unneddylated inactive form with no or minimum effects on other cullin members. Our data firmly establish a previously unrecognized specific role of the DCN1-UBC12 interaction for cellular neddylation of cullin 3. Our compounds represent the first-in-class of selective inhibitors of a specific cullin member, and are excellent probe compounds to investigate the role of the cullin 3 ligase in biological processes and human diseases. We will also discuss their potential therapeutic applications.