Peroxynitrite modulates acidic fibroblast growth factor (FGF-1) activity

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Signaling

Background:

• Acidic fibroblast growth factor (FGF-1) is crucial for cellular processes.
• The role of peroxynitrite (ONOO(-)) in modulating FGF-1 function is not fully understood.
• Investigating post-translational modifications of FGF-1 by ONOO(-) is key to understanding its regulation.

Purpose of the Study:

• To determine if peroxynitrite (ONOO(-)) mediates acidic fibroblast growth factor (FGF-1) function.
• To identify specific amino acid modifications induced by ONOO(-) in FGF-1.
• To correlate these modifications with changes in FGF-1's biologic activity.

Main Methods:

• Recombinant human FGF-1 was treated with varying concentrations of peroxynitrite (ONOO(-)) in vitro.
• Amino acid modifications (cysteine oxidation, dityrosine formation, tyrosine/tryptophan nitration) were analyzed.
• Biologic activity of modified FGF-1 was assessed, along with aggregate formation and reversibility.
• Mass spectrometry and spectral analysis identified nitrated residues.

Main Results:

• Low ONOO(-) concentrations (10-50 microM) induced dityrosine formation and reducible FGF-1 aggregates with latent activity.
• Higher ONOO(-) concentrations (0.1-0.5mM) led to non-reducible, inactivated FGF-1 structures.
• Six residues (Y29, Y69, Y108, Y111, Y139, W121) were identified as nitrated by ONOO(-).
• Nitration of Y108 and Y111 in a mutant FGF-1 correlated with irreversible inhibition of activity.

Conclusions:

• Low ONOO(-) levels may facilitate FGF-1 secretion as a complex with latent activity.
• High ONOO(-) levels cause irreversible inactivation of FGF-1 through cysteine oxidation and tyrosine nitration.
• This ONOO(-)-mediated inactivation serves as a feedback mechanism during inflammation resolution and tissue repair.