Macrocyclic peptides that inhibit Wnt signalling via interaction with Wnt3a

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Wnt proteins are crucial signaling molecules involved in development and disease.
• Targeting Wnt proteins has been challenging due to their hydrophobic nature.
• Wnt signaling pathways are implicated in various cancers and developmental disorders.

Purpose of the Study:

• To discover novel macrocyclic peptides that bind to Wnt3a.
• To develop inhibitors of Wnt3a signaling.
• To overcome challenges in targeting hydrophobic Wnt proteins.

Main Methods:

• Random non-standard Peptides Integrated Discovery (RaPID) system for de novo peptide discovery.
• In vitro selection against mouse Wnt3a (mWnt3a) complexed with human afamin (hAFM).
• Block-mutagenesis scanning display for optimizing peptide inhibitors.

Main Results:

• Identification of macrocyclic peptides binding mWnt3a with dissociation constants (K_D) as low as 110 nM.
• Demonstration of Wnt3a signaling inhibition by a lead peptide, WAp-D04, in a Wnt3a-dependent reporter cell line.
• Development of an optimized inhibitor, WAp-D04-W10P, exhibiting 5-fold increased potency.

Conclusions:

• This study reports the first molecules capable of inhibiting Wnt signaling via direct interaction with a Wnt protein.
• The developed macrocyclic peptides represent a promising new class of therapeutics for Wnt-mediated diseases.
• The findings provide a novel strategy for targeting previously intractable hydrophobic protein targets.