Development of High-Affinity Ligands for Human UBR2

Area of Science:

• Biochemistry
• Structural Biology
• Drug Discovery

Background:

• UBR box-containing E3 ligases target protein N-termini.
• UBR2 is a therapeutic target for cachexia associated with cancer and diabetes.
• High-affinity small-molecule ligands for UBR2 are currently lacking.

Purpose of the Study:

• To develop high-affinity small-molecule ligands for UBR2.
• To elucidate the molecular mechanisms of UBR2 ligand binding.
• To evaluate the therapeutic potential of UBR2 ligands in cachexia models.

Main Methods:

• Peptidomimetic approach incorporating unnatural amino acids.
• High-resolution cocrystal structural analysis (∼1.2 Å).
• In vitro binding assays to determine affinity (Kd) and selectivity.
• In vitro cellular models of cancer-induced cachexia.

Main Results:

• Developed UBR2 ligands with high affinity (Kd ∼ 20-40 nM).
• Achieved 10-fold selectivity for UBR2 over its homolog UBR1.
• Determined high-resolution structures revealing binding mechanisms.
• Demonstrated attenuation of cancer-induced cachexia in a cellular model.

Conclusions:

• UBR boxes are druggable targets.
• High-affinity UBR2 ligands can be developed using peptidomimetics.
• These findings support targeting UBR E3 ligases for novel cachexia therapeutics.