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Glycosaminoglycans differentially bind HARP and modulate its biological activity
F Vacherot1, J Delbé, M Heroult
1Laboratoire de Recherche sur la Croissance Cellulaire, la Réparation et la Régénération Tissulaires (CRRET), Unité Propre de Recherche de l'Enseignement Supérieur Associées an CNRS CNRS 7053, Université Paris XII-Val de Marne, France.
The Journal of Biological Chemistry
|March 13, 1999
Summary
Heparin affin regulatory peptide (HARP) binds to extracellular matrix proteoglycans, influencing cell proliferation. Heparin and other sulfates potentiate HARP
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Heparin affin regulatory peptide (HARP) is a heparin-binding growth factor.
- HARP's high affinity for heparin suggests binding to cell-surface and extracellular matrix heparan sulfate proteoglycans.
Purpose of the Study:
- To investigate HARP binding to extracellular proteoglycans.
- To determine the role of proteoglycans in HARP's biological activity.
Main Methods:
- Western blot analysis to detect HARP bound to proteoglycans.
- Heparitinase treatment to assess HARP-induced cell proliferation.
- Biosensor analysis to quantify HARP binding kinetics to different glycosaminoglycans.
Main Results:
- HARP was detected bound to heparan sulfate proteoglycans in multiple cell lines.
- Heparitinase treatment inhibited HARP-induced proliferation, which was restored by heparin.
- Heparan sulfate, dermatan sulfate, and chondroitin sulfate A displaced HARP from the extracellular compartment.
- HARP exhibited fast binding kinetics to heparin (Kd = 13 nM) and slower kinetics to dermatan sulfate (Kd = 51 nM).
- Exogenous heparin, heparan sulfate, and dermatan sulfate enhanced HARP's growth-stimulatory activity.
Conclusions:
- Proteoglycans, particularly heparan sulfate and dermatan sulfate, are involved in HARP binding and mitogenic activity regulation.
- The interaction kinetics and affinity vary between HARP and different glycosaminoglycans.
- These findings highlight the crucial role of extracellular matrix interactions in modulating HARP function.