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Updated: Jan 16, 2026
Peptide-based Identification of Functional Motifs and their Binding Partners
Published on: June 30, 2013
Selective and Potent Peptide Binders of RNF43 for Wnt Signaling Inhibition
Sunhee Hwang1, Paula Flórez Salcedo1, Antonion Korcari1
1Departments of †Peptide Therapeutics, ‡Regenerative Medicine, §Structural Biology, ∥Small Molecule Analytical Chemistry and Quality Control, ⊥Microchemistry, Proteomics and Lipidomics, Genentech Inc., South San Francisco, California 94080, United States.
Abstract:
The Wnt/β-catenin pathway is critical in human tumor progression. Cell-surface transmembrane E3 ubiquitin ligase ring finger 43 negatively regulates Wnt signaling through ubiquitination of Wnt coreceptor Frizzled. Aberrant Wnt signaling through inactivating mutations of RNF43 has been identified in various forms of cancers, highlighting its significance in tumor biology. However, the precise mechanism underlying the function of RNF43 remains elusive, largely due to the absence of selective molecular tools allowing for detection or manipulation of endogenous RNF43. Here we present a series of disulfide-constrained peptides, including GUR-1.6.12.2, which exhibit high affinity and specificity against RNF43. GUR-1.6.12.2 can be used as a valuable research tool to delineate RNF43 activity in various contexts. We showcased its application in immunofluorescence, where RNF43 was detected in intestinal crypts using biotinylated GUR-1.6.12.2. We then combined experimental and computational structural approaches to propose a model of GUR-1.6.12.2 and its binding to RNF43. Importantly, we generated a functional RNF43-DCP by producing a hexavalent GUR-1.6.12.2 molecule, which exhibited inhibitory activity against Wnt signaling in cells by competing with R-spondin, a RNF43 ligand that potentiates signaling. The RNF43 binders presented here offer new opportunities for the research and development of anticancer therapies targeting Wnt signaling with improved selectivity.
Insights
Researchers developed novel peptides targeting Ring finger 43 (RNF43), a key regulator of Wnt signaling implicated in cancer. These tools enable RNF43 detection and inhibition, paving the way for new cancer therapies.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- The Wnt/β-catenin pathway is crucial for human tumor progression.
- Ring finger 43 (RNF43), a cell-surface E3 ubiquitin ligase, negatively regulates Wnt signaling by ubiquitylating the Frizzled co-receptor.
- Inactivating mutations in RNF43 are linked to various cancers, underscoring its role in tumor biology, yet its precise mechanism remains unclear due to a lack of specific molecular tools.
Purpose of the Study:
- To develop selective molecular tools for detecting and manipulating endogenous Ring finger 43 (RNF43).
- To investigate the mechanism of RNF43 function and its role in Wnt signaling.
- To explore the therapeutic potential of RNF43-targeting agents in cancer treatment.
Main Methods:
- Design and synthesis of disulfide-constrained peptides with high affinity and specificity for RNF43.
- Application of biotinylated peptides in immunofluorescence for RNF43 detection in intestinal crypts.
- Integration of experimental and computational structural analyses to model peptide-RNF43 binding.
- Generation of a hexavalent RNF43 binder (RNF43-DCP) to inhibit Wnt signaling.
Main Results:
- A peptide, GUR-1.6.12.2, was identified with high affinity and specificity for RNF43.
- RNF43 was successfully detected in intestinal crypts using biotinylated GUR-1.6.12.2 via immunofluorescence.
- A structural model of GUR-1.6.12.2 binding to RNF43 was proposed.
- The RNF43-DCP demonstrated inhibitory activity against Wnt signaling by competing with R-spondin.
Conclusions:
- The developed RNF43 binders serve as valuable research tools for studying RNF43 activity.
- These binders facilitate the investigation of RNF43's role in various biological contexts.
- The RNF43-DCP shows potential as a therapeutic agent for targeting Wnt signaling in anticancer strategies.
- This work offers new avenues for developing selective anticancer therapies focused on the Wnt pathway.
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