Sulfated oligosaccharides (heparin and fucoidan) binding and dimerization of stromal cell-derived factor-1 (SDF-1/CXCL 12) are coupled as evidenced by affinity CE-MS analysis

Abstract

Chemokine stromal cell-derived factor-1 (SDF-1) is a potent chemoattractant involved in leukocyte trafficking and metastasis. Heparan sulfate on the cell surface binds SDF-1 and may modulate its function as a coreceptor of this chemokine. A major effect of the glycosaminoglycan binding may be on the quaternary structure of SDF-1, which has been controversially reported as a monomer or a dimer. We have investigated the effect of sulfated oligosaccharides on the oligomerization of SDF-1 and of its mutated form SDF-1 (3/6), using affinity capillary electrophoresis (ACE) hyphenated to mass spectrometry (MS). Coupled to MS, ACE allowed the study for the first time of the effect of size-defined oligosaccharides on the quaternary organization of SDF-1 in muM range concentrations, i.e., lower values than the mM values previously reported in NMR, light scattering, and ultracentrifugation experiments. Our results showed that in the absence of sulfated oligosaccharides, SDF-1 is mostly monomeric in solution. However, dimer formation was observed upon interaction with heparin-sulfated oligosaccharides despite the mM Kd values for dimerization. A SDF-1/oligosaccharide 2/1 complex was detected, indicating that oligosaccharide binding promoted the dimerization of SDF-1. Heparin tetrasaccharide but not disaccharide promoted dimer formation, suggesting that the dimer required to be stabilized by a long enough bound oligosaccharide. The SDF-1/oligosaccharide 1/1 complex was only observed with heparin disaccharide and fucoidan pentasaccharide, pointing out the role of specific structural determinants in promoting dimer formation. These results underline the importance of dimerization induced by glycosaminoglycans for chemokine functionality.

Heparin Oligosaccharides Inhibit Chemokine (CXC Motif) Ligand 12 (CXCL12) Cardioprotection by Binding Orthogonal to the Dimerization Interface, Promoting Oligomerization, and Competing with the Chemokine (CXC Motif) Receptor 4 (CXCR4) N Terminus

“…The antithrombotic properties of heparin are well established and highlighted by its presence as a clinical mainstay for the treatment of myocardial infarction. Because soluble heparin binds to and promotes dimerization of the chemokine (25,26) and inhibits cell migration in vitro (30), we hypothesized that this interaction would also attenuate CXCL12-mediated cardioprotection.…”

“…2). Because heparin binding promotes CXCL12 dimerization (25,26), we concluded that heparin-induced shifts arose from a combination of GAG-protein and protein-protein contacts.…”

“…We recently demonstrated that CXCL12 is cardioprotective over a narrow concentration range, whereas a constitutively dimeric form of the chemokine exerts little to no effect (19). Because heparin is commonly administered in response to myocardial infarctions (2) and induces CXCL12 dimerization (25,26), we hypothesized that the protective properties of CXCL12 may be attenuated by interactions with soluble heparin in a modern clinical setting.…”

Novel stable cytokine delivery system in physiological pH solution: chitosan oligosaccharide/heparin nanoparticles

“…19 Therefore, it should be possible to develop CSO-based nanoparticles that are stable in solutions with physiological pH. Many growth factors, such as stromal cell-derived factor (SDF)-1α, vascular endothelial growth factor (VEGF), placental growth factor, platelet-derived growth factor, and fibroblast growth factor, [20][21][22][23] can bind to heparin through their conserved amino acid sequences. Several heparin-containing cytokine delivery systems have been developed for tissue regeneration and modified to control the release of cytokines.…”

Incorporation of heparin-binding proteins into preformed dextran sulfate-chitosan nanoparticles

“…[20][21][22] It has a distinct heparin-binding site, 23,24 exists mainly as a monomer in solution, but forms a dimer upon binding to heparin. 24,25 The incorporation reaction was carried out by mixing SDF-1α with DSCS NPs at various ratios, followed by a centrifugation to separate unincorporated SDF-1α from DSCS NPs. The amount of SDF-1α in pellet and supernatant fractions was analyzed on SDS gels.…”