Modulation of FGF pathway signaling and vascular differentiation using designed oligomeric assemblies.

Area of Science:

• Cellular signaling and molecular biology.
• Protein engineering and synthetic biology.
• Developmental biology and cell fate determination.

Background:

• Growth factors and cytokines initiate intracellular signaling cascades by binding to receptor tyrosine kinases.
• Understanding how receptor clustering (valency and geometry) influences signaling is crucial for controlling cellular responses.
• Fibroblast growth factor receptors (FGFRs) play key roles in vascular development.

Approach:

• Designed cyclic homo-oligomeric protein scaffolds with modular repeat units, accommodating up to 8 subunits.
• Incorporated a de novo designed fibroblast growth factor receptor (FGFR) binding module into the scaffolds.
• Generated synthetic signaling ligands to systematically probe valency- and geometry-dependent signaling outcomes.

Key Points:

• The designed synthetic ligands demonstrated potent, valency- and geometry-dependent activation of Ca2+ release and MAPK pathways.
• High specificity of the designed agonists allowed for the elucidation of distinct roles for two FGFR splice variants.
• These variants were shown to drive endothelial and mesenchymal cell fates during early vascular development.

Conclusions:

• The modular design of cyclic scaffolds and incorporated binding modules provides a versatile platform for probing and manipulating cellular signaling.
• This approach enables precise control over receptor activation, offering new tools for studying developmental processes and potentially therapeutic applications.