Fibroblast growth factor 2-antagonist activity of a long-pentraxin 3-derived anti-angiogenic pentapeptide.
Bottom Line: In all the assays the mutated Ac-ARPSA-NH(2) peptide was ineffective.In keeping with the observation that hydrophobic interactions dominate the interface between FGF2 and the FGF-binding domain of the Ig-like loop D2 of FGFR1, amino acid substitutions in Ac-ARPCA-NH(2) and saturation transfer difference-nuclear magnetic resonance analysis of its mode of interaction with FGF2 implicate the hydrophobic methyl groups of the pentapeptide in FGF2 binding.These results will provide the basis for the design of novel PTX3-derived anti-angiogenic FGF2 antagonists.
Affiliation: Unit of General Pathology and Immunology, Department of Biomedical Sciences and Biotechnology, School of Medicine, University of Brescia, Brescia, Italy.Show MeSH
Mentions: Several observations support this hypothesis. (i) As stated above, STD NMR experiments have shown that only the methyl protons of Ala1, Ala5 and of the N-terminal blocking acetyl group receive saturation transfer following FGF2 interaction whereas no evidence could be found for hydrophilic contacts between ARPCA peptide and FGF2. Interestingly, hydrophobic interactions with FGF2 have been observed also for the C-terminal fragment of Platelet Factor-4 , a well-known anti-angiogenic FGF2 antagonist . (ii) ARPCA prevents FGF2/FGFR1 interaction with no effect on the heparin binding capacity of the growth factor. Accordingly, FGFR- and heparin-binding regions represent distinct domains in the FGF2 molecule . (iii) ARPCA inhibits FGF2 interactions with all four mammalian FGFRs. (iv) ARPCA also inhibits the biological activity of FGF1 and FGF8b without exerting any effect on the activity of different mitogens. (v) A model of the proposed interaction was built by conformational analysis (see the ‘Computational methods’ paragraph in the ‘Methods’ section and Fig. 5). The conformational analysis performed on ARPCA peptide indicates that the most stable family of conformers show a type-I β-turn between Pro and Cys residues, thus supporting the conformational role of the RPC sequence, and close distances between Ala1 and Ala5 methyls . The superposition of the global minimum conformation of ARPCA peptide to the b-sheet region 164–170 of the hydrophobic domain D2 of FGFR1 indicated that the peptide could interact with FGF2 by mimicking this highly conserved FGF2-binding region of the receptor. Further experiments are required to confirm this hypothesis.
Affiliation: Unit of General Pathology and Immunology, Department of Biomedical Sciences and Biotechnology, School of Medicine, University of Brescia, Brescia, Italy.