Homodimerization controls the fibroblast growth factor 9 subfamily's receptor binding and heparan sulfate-dependent diffusion in the extracellular matrix.
Uncontrolled fibroblast growth factor (FGF) signaling can lead to human diseases, necessitating multiple layers of self-regulatory control mechanisms to keep its activity in check. Herein, we demonstrate that FGF9 and FGF20 ligands undergo a reversible homodimerization, occluding their key receptor binding sites. To test the role of dimerization in ligand autoinhibition, we introduced structure-based mutations into the dimer interfaces of FGF9 and FGF20. The mutations weakened the ability of the ligands to dimerize, effectively increasing the concentrations of monomeric ligands capable of binding and activating their cognate FGF receptor in vitro and in living cells. Interestingly, the monomeric ligands exhibit reduced heparin binding, resulting in their increased radii of heparan sulfate-dependent diffusion and biologic action, as evidenced by the wider dilation area of ex vivo lung cultures in response to implanted mutant FGF9-loaded beads. Hence, our data demonstrate that homodimerization autoregulates FGF9 and FGF20's receptor binding and concentration gradients in the extracellular matrix. Our study is the first to implicate ligand dimerization as an autoregulatory mechanism for growth factor bioactivity and sets the stage for engineering modified FGF9 subfamily ligands, with desired activity for use in both basic and translational research.
Kalinina
Juliya
J
Department of Pharmacology of New York University School of Medicine, New York, New York 10016, USA.
Byron
Sara A
SA
Makarenkova
Helen P
HP
Olsen
Shaun K
SK
Eliseenkova
Anna V
AV
Larochelle
William J
WJ
Dhanabal
Mohanraj
M
Blais
Steven
S
Ornitz
David M
DM
Day
Loren A
LA
Neubert
Thomas A
TA
Pollock
Pamela M
PM
Mohammadi
Moosa
M
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D018360:Crystallography, X-Ray; D004058:Diffusion; D019281:Dimerization; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D051525:Fibroblast Growth Factor 9 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005346:Fibroblast Growth Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006497:Heparan Sulfate / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011247:Pregnancy; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
D051525:Fibroblast Growth Factor 9; D005346:Fibroblast Growth Factors; D006497:Heparan Sulfate; D008024:Ligands; D051496:Receptor, Fibroblast Growth Factor, Type 1; C512705:FGF16 protein, human; C416003:FGF20 protein, human