Targeting the Tcf4 G13ANDE17 binding site to selectively disrupt β-catenin/T-cell factor protein-protein interactions

Area of Science:

• Molecular Biology
• Drug Discovery
• Biochemistry

Background:

• Protein-protein interactions are vital for cellular networks and represent therapeutic targets.
• β-Catenin, a key Wnt pathway protein, interacts with T-cell factor (Tcf), cadherin, and adenomatous polyposis coli (APC) via a shared binding site.
• Aberrant β-catenin/Tcf interactions drive cancer and fibrosis, while other interactions are crucial for cell adhesion and protein degradation.

Purpose of the Study:

• To identify a selective binding site differentiating β-catenin interactions.
• To design selective small-molecule inhibitors targeting the β-catenin/Tcf interaction.
• To validate the efficacy and selectivity of designed inhibitors.

Main Methods:

• Alanine scanning and biochemical assays to identify selective binding sites.
• Peptidomimetic strategy using SiteMap and multiple-copy simultaneous search for inhibitor design.
• Biochemical and cell-based assays to evaluate inhibitor potency and selectivity.

Main Results:

• A selective binding site distinguishing β-catenin/Tcf from β-catenin/cadherin and β-catenin/APC interactions was identified.
• A potent small-molecule inhibitor was designed that binds β-catenin and disrupts β-catenin/Tcf interactions.
• The inhibitor demonstrated dual selectivity, inhibiting β-catenin/Tcf interactions over β-catenin/cadherin and β-catenin/APC interactions in vitro and in cells.

Conclusions:

• Selective disruption of specific protein-protein interactions is achievable with small molecules.
• The developed peptidomimetic strategy is effective for designing selective inhibitors.
• This study provides a proof of concept for targeting β-catenin/Tcf interactions therapeutically.