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

Many growth factors and cytokines signal by binding to the extracellular domains of their receptors and driving association and transphosphorylation of the receptor intracellular tyrosine kinase domains, initiating downstream signaling cascades. To enable systematic exploration of how receptor valency and geometry affect signaling outcomes, we designed cyclic homo-oligomers with up to 8 subunits using repeat protein building blocks that can be modularly extended. By incorporating a de novo -designed fibroblast growth factor receptor (FGFR)-binding module into these scaffolds, we generated a series of synthetic signaling ligands that exhibit potent valency- and geometry-dependent Ca2+ release and mitogen-activated protein kinase (MAPK) pathway activation. The high specificity of the designed agonists reveals distinct roles for two FGFR splice variants in driving arterial endothelium and perivascular cell fates during early vascular development. Our designed modular assemblies should be broadly useful for unraveling the complexities of signaling in key developmental transitions and for developing future therapeutic applications. [Display omitted] • De novo designed cyclic oligomers with tunable geometric properties • Oligomeric FGFR-binding modules induce geometry- and valency-dependent signaling • Modulation of FGFR isoform activity controls cell fate during vascular development • FGFR c-isoform activation favors arterial fate, while b-isoform favors perivascular fate De novo designed synthetic agonists against the c-isoform of the FGF receptor are used to specifically control cellular fate in a vascular endothelial cell differentiation model. [ABSTRACT FROM AUTHOR]