First-in-Class Molecular Glue Selectively Degrades Spliceosome Protein WBP4 via CRBN
- Discovered dWBP4-1 through proteomic profiling of a CRBN-binding compound library, followed by SAR optimization.
- Acts as a molecular glue, forming a CRBN ternary complex via a canonical G-loop-mediated interaction to recruit WBP4 (WW domain-binding protein 4), a spliceosome-associated scaffold protein.
- Degradation is rapid and occurs at nanomolar concentrations.
- Selectivity across the proteome is reported as high, with minimal downstream transcriptomic or alternative-splicing effects observed elsewhere.
- Mapped a minimal ~41-residue WBP4 degron sequence and used it to build "wTAG," a fusion-tag degradation platform.
- wTAG enables monotonic, dose-dependent degradation without the hook effect seen in some bifunctional degraders.
A canonical G-loop-mediated ternary complex — reassuring, not exotic: this is the same validated CRBN surface, not a new liability profile to characterize from scratch. The compact ~41-residue degron is the real tell for tractability — that's a defined element, not a diffuse IDR, so SAR here should be rational rather than lucky. Nanomolar potency with reported high proteome-wide selectivity is the headline number, though for a spliceosome-associated protein I'd want orthogonal splicing/transcriptomic data before fully trusting "minimal downstream effects." The piece I'd actually chase into my own work is wTAG: a monovalent, hook-effect-free degron tag beats dTAG-style bifunctional systems for clean dose-response in target-validation studies, regardless of whether WBP4 itself ever becomes a drug target.