Biomedical subjects

Sally E Stringer

Publications and source records attributed to Sally E Stringer.

4 recordsLinked to original sources

PubMed2003

Interaction of platelet factor 4 with fibroblast growth factor 2 is stabilised by heparan sulphate.

The CXC chemokine platelet factor 4 (PF4) appears to inhibit tumour growth through its modulation of the activity of angiogenic growth factors. We investigated the heparan sulphate-dependent mechanism of PF4 inhibition of fibroblast growth factor 2 (FGF-2). The ability of PF4 to bind simultaneously to both FGF-2 and HS was assessed using affinity gel chromatography. Thirty-three to forty-two percent more HS bound to the FGF-2 affinity gel in the presence of PF4 than with HS alone. Protection assays showed that PF4 and FGF-2 bound to adjacent or overlapping sites together covering a 12 kDa stretch of HS. This study suggests that the three components may form a ternary complex. PF4 released at sites of angiogenesis may bind to angiogenic growth factors attached to endothelial cell surface HS to disrupt or prevent them from interacting with their signalling receptors. Manipulation of this mechanism may prove useful for clinical intervention of angiogenesis.

3T3 Cells↗

PubMed2002

Heparin sequencing.

Heparin is a highly sulfated glycosaminoglycan widely used as an anticoagulant. Modifications in its relatively uniform structure appear to be key to its recognition and modulation of serine proteases, growth factors, chemokines, and extracellular proteins, as has been most clearly demonstrated in the antithrombin binding site. We sequenced the major oligosaccharides released from mastocytoma heparin by partial nitrous acid using a highly sensitive technique tailored for sequencing of metabolically radiolabeled heparin. It utilizes partial nitrous acid cleavage to allow simultaneous sequencing of the internal components of the oligosaccharide under investigation by specific lysosomal exoenzymes. Sequencing revealed that although the majority of the heparin disaccharides are N-, 2-O-, and 6-O-sulfated, the less sulfated disaccharides (lacking 2-O- or 6-O-sulfates) seem to be spaced out along the chain. The technique may be particularly useful for characterizing heparin from novel sources, such as the glial progenitor cells and Ascidia, as well as for sequencing protein binding sites.

Animals↗

PubMed2002

Identification of an MIP-1alpha -binding heparan sulfate oligosaccharide that supports long-term in vitro maintenance of human LTC-ICs.

We previously showed that heparan sulfate (HS) is required for in vitro cytokine + chemokine-mediated maintenance of primitive human hematopoietic progenitors. However, HS preparations are mixtures of polysaccharide chains of varying size, structure, and protein-binding abilities. Therefore, we examined whether the long-term culture-initiating cells (LTC-IC) supportive capability of HS is attributable to an oligosaccharide of defined length and protein-binding ability. Oligosaccharides of a wide range of sizes were prepared, and their capability to support human marrow LTC-IC maintenance in the presence of low-dose cytokines and a single chemokine, macrophage inflammatory protein-1alpha (MIP-1alpha), was examined. LTC-IC supportive capability of HS oligosaccharides correlated directly with size and MIP-1alpha binding ability. A specific MIP-1alpha-binding HS oligosaccharide preparation of M(r) 10 kDa that optimally supported LTC-IC maintenance was identified. This oligosaccharide had the structure required for MIP-1alpha binding, which we have recently described. The present study defines the minimum size and structural features of LTC-IC supportive HS.

Antigens, CD34↗

PubMed2002

Characterization of the binding site on heparan sulfate for macrophage inflammatory protein 1alpha.

The CC chemokine macrophage inflammatory protein 1alpha (MIP1alpha) is a key regulator of the proliferation and differentiation of hematopoietic progenitor cells. The activity of MIP1alpha appears to be modulated by its binding to heparan sulfate (HS) proteoglycans, ubiquitous components of the mammalian cell surface and extracellular matrix. In this study we show that HS has highest affinity for the dimeric form of MIP1alpha. The predominantly dimeric BB10010 MIP1alpha interacts with an 8.3-kDa sequence in the HS polysaccharide chain, which it protects from degradation by heparinase enzymes. The major structural motif of this HS fragment appears to consist of 2 sulfate-rich S-domains separated by a short central N-acetylated region. The optimum lengths of these S-domains seem to be 12 to 14 saccharides. We propose that this binding fragment may wrap around the MIP1alpha dimer in a horseshoe shape, facilitating the interaction of the S-domains with the heparin-binding domains on each monomer. Molecular modeling suggests that these S-domains are likely to interact with basic residues Arg 17, Arg 45, and Arg 47 and possibly with Lys 44 on MIP1alpha and that the interconnecting N-acetylated region is of sufficient length to allow the 2 S-domains to bind to these sites on opposite faces of the dimer. Elucidation of the structure of the HS-binding site for MIP1alpha may enable us to devise ways of enhancing its myeloprotective or peripheral blood stem cell mobilization properties, which can be used to improve cancer chemotherapy treatments.

Binding Sites↗