Truncated FGF-18 Polypeptides Enhancing FGFR3 Specificity
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Solution Overview
Problem
There is an unmet need for highly selective Fibroblast Growth Factor (FGF) variants that can selectively stimulate or inhibit FGF receptor subtypes, particularly for treating cartilage and skeletal disorders, as existing methods lack specificity and efficacy in targeting FGFR3.
Innovation Solution
Development of N-terminal truncated FGF-18 polypeptides with specific N-terminal truncations beyond the signal peptide domain, which exhibit increased receptor specificity for FGFR3, allowing for selective activation and inhibition of chondrocyte proliferation and differentiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If N-terminal truncation is applied to FGF-18, then receptor specificity for FGFR3 is improved, but biological activity breadth is reduced
Solution Approach 1:
The FGF-18 protein is segmented by removing specific N-terminal regions (signal peptide and additional residues) to create truncated variants that selectively bind FGFR3. This segmentation allows the core functional domain to retain activity while the removed segments are responsible for broad receptor binding, thereby achieving specificity through structural division.
Solution Approach 2:
The signal peptide sequence (residues 1-27) and additional N-terminal residues are extracted from the full-length FGF-18 protein. This extraction removes the portions responsible for non-specific binding while preserving the FGFR3-specific binding capability in the truncated variant.
2Productivity
If FGF-18 is used to stimulate chondrocyte proliferation, then cartilage formation is promoted, but uncontrolled proliferation occurs
Solution Approach 1:
The truncated FGF-18 variant is designed with localized functional properties: it specifically activates FGFR3 signaling pathways that promote chondrocyte differentiation and matrix production while avoiding activation of other FGF receptors that would drive uncontrolled proliferation. This local quality control ensures therapeutic benefit without harmful side effects.
Solution Approach 2:
The biological activity parameters of FGF-18 are changed by modifying its receptor binding profile through truncation. The variant exhibits altered specificity parameters, showing high selectivity for FGFR3 while having reduced or eliminated activity toward other FGF receptors, thereby controlling the biological outcome to promote differentiation rather than unchecked proliferation.
3Adaptability or versatility
If full-length FGF-18 is used, then broad receptor binding is achieved, but selectivity for FGFR3 is reduced
Solution Approach 1:
The N-terminal signal peptide and additional residues are extracted from full-length FGF-18. These extracted regions contain sequences that enable broad receptor binding, and their removal results in a truncated protein that selectively binds only FGFR3, thereby achieving the desired selectivity.
Solution Approach 2:
The binding affinity parameters of FGF-18 are changed through truncation. The truncated variant exhibits significantly increased binding selectivity for FGFR3 compared to other FGF receptors, transforming the receptor interaction profile from broad and non-specific to narrow and highly specific.
Data Source
AI summary
The present invention relates to fibroblast growth factor 18 (FGF-18) variants having various truncations beyond the signal peptide domain of the N-terminus, which activate FGFR3 with increased specificity. The invention further relates to polynucleotides encoding the variants, pharmaceutical compositions comprising same and methods for use thereof in treating cartilage and skeletal disorders.