Analysis of the interaction between heparin and follistatin and heparin and follistatin-ligand complexes using surface plasmon resonance.
Biochemistry
; 51(34): 6797-803, 2012 Aug 28.
Article
em En
| MEDLINE
| ID: mdl-22809401
ABSTRACT
Heparin and related heparan sulfate interact with a number of cytokines and growth factors, thereby playing an essential role in many physiological and pathophysiological processes by involving both signal transduction and the regulation of the tissue distribution of cytokines/growth factors. Follistatin (FS) is an autocrine protein with a heparin-binding motif that serves to regulate the cell proliferative activity of the paracrine hormone, and member of the TGF-ß family, activin A (ActA). Follistatin is currently under investigation as an antagonist of another TGF-ß family member, myostatin (Mstn), for the promotion of muscle growth in diseases associated with muscle atrophy. In this study, we employ surface plasmon resonance (SPR) spectroscopy to dissect the binding interactions between the heparin polysaccharide and both free follistatin (FS288) and its complexes (FS288-ActA and FS288-Mstn). FS288 complexes show much higher heparin binding affinity than FS288 alone. SPR solution competition studies using heparin oligosaccharides showed that the binding of FS288 and its complex to heparin is dependent on chain length. Full chain heparin or large oligosaccharides, having 18-20 sugar residues, show the highest binding activity for FS288 and the FS288-ActA complex, whereas smaller heparin molecules could interact with the FS288-Mstn complex. These interactions were also analyzed in normal physiological buffers and at different salt concentrations and pH values. Unbound follistatin was much more sensitive to all salt concentrations of >150 mM. The binding of heparin to the FS288-ActA complex was disrupted at 500 mM salt, whereas it was actually strengthened for the FS288-Mstn complex. At acidic pH values, binding of heparin to FS288 and the FS288-ActA complex was enhanced. While slightly acidic pH values (pH 6.2 and 5.2) enhanced the binding of the FS288-Mstn complex to heparin, at pH 4 heparin binding was inhibited. Overall, these studies demonstrate that binding of a specific ligand to FS288 differentially regulates its affinity and behavior for heparin molecules.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Heparina
/
Ressonância de Plasmônio de Superfície
/
Folistatina
Tipo de estudo:
Evaluation_studies
Limite:
Humans
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Estados Unidos