Glycosaminoglycans Promote HARP/PTN Dimerization

• Published in: Biochemical and biophysical research communications 1999-12, Vol.266 (2), p.437-442
• Main Authors: Bernard-Pierrot, Isabelle, Héroult, Mélanie, Lemaítre, Gilles, Barritault, Denis, Courty, José, Milhiet, Pierre Emmanuel
• Format: Article
• Language: English
• Subjects: 3T3 Cells; Animals; Carrier Proteins - chemistry; Chlorates - chemistry; Chondroitin Sulfates - chemistry; Cross-Linking Reagents - chemistry; Cytokines - chemistry; Dermatan Sulfate - chemistry; Dimerization; Glycosaminoglycans - chemistry; Heparin - chemistry; Humans; Immunoblotting; Mice; Succinimides - chemistry; Transfection
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1999.1835

Heparin affin regulatory peptide (HARP), also called pleiotrophin (PTN), is a secreted polypeptide which binds to heparin and plays a key role in cellular growth and differentiation. In order to assess the determinants potentially important to its biological activity, we tested the ability of HARP to oligomerize, a process involved in mitogenic activity of the heparin-binding fibroblast growth factor. Using dissuccinimidyl suberate cross-linking experiments and affinity chromatography, we report that human HARP forms noncovalent dimers. Dimerization is dependent on the presence of heparin or other sulfated glycosaminoglycans, as chlorate treatment of cells inhibits this process. In vitro, different glycosaminoglycans, such as dermatan sulfate and chondroitin sulfate-C, also induce a dimer assembly of HARP. The relevance of this process was supported by experiments demonstrating that HARP is secreted as a dimer in conditioned medium of NIH-3T3 cells that overexpressed this growth factor and is also associated to the cell surface or to the extracellular matrix.