RESUMO
Fibroblast growth factors (FGFs) are regulatory proteins associated with a number of physiological and pathological states. On the basis of data suggesting a functional role for specific regions of human acidic FGF (aFGF), a linear peptide encompassing residues 99-108 (peptide1) and its cyclic analogue (peptide 2) were synthesized and their functional and structural features were investigated. While peptide 1 is inactive on Balb/c 3T3 fibroblasts, peptide 2 is mitogenic with ED(50) of approximately 50 microM. Moreover, peptide 1 is not able to inhibit the binding of human aFGF to cellular receptors whereas peptide 2 exhibits significant inhibitory activity. The NMR-derived solution conformers indicated the presence, only in peptide 2, of structural elements that we believe are related to its ability to emulate the biological activity of the native protein. These results suggest that the expression of mitogenic activity in short peptides, besides the presence of specific amino acids, requires the existence of stable structural features. In addition, they indicate that the introduction of chemical restraints in peptides can provide novel possibilities for the development of receptor agonists or antagonists.
Assuntos
Fator 1 de Crescimento de Fibroblastos/química , Fatores de Crescimento de Fibroblastos/síntese química , Mitógenos/síntese química , Oligopeptídeos/síntese química , Fragmentos de Peptídeos/síntese química , Peptídeos Cíclicos/síntese química , Células 3T3 , Animais , Dicroísmo Circular , Fatores de Crescimento de Fibroblastos/química , Fatores de Crescimento de Fibroblastos/farmacologia , Humanos , Espectroscopia de Ressonância Magnética , Camundongos , Mitógenos/química , Mitógenos/farmacologia , Modelos Moleculares , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/farmacologia , Peptídeos Cíclicos/química , Peptídeos Cíclicos/farmacologia , Conformação Proteica , Timidina/metabolismoRESUMO
The synthetic peptide Ac-WFVGLKKNGSSKRGPRT-NH2,related to the human FGF-1 sequence, was shown to be mitogenic upon Balb/c 3T3 fibroblasts in culture (ED50=10-20 muM) and to compete with the growth factor for cellular binding (ID50 = 30-50 muM). The results described suggest that the mitogenic activity of the peptide is dependent on the presence of the residues 122-127 (WFVGLK) in its structure. Also, its affinity for the cellular receptors seems to be dependent on the presence of residues that are important for FGF-heparin binding such as K127, K133 and R137.
