Structural Requirements for Heparin/Heparan Sulfate Binding to Type V Collagen

Abstract

Collagen-proteoglycan interactions participate in the regand native collagen V molecules formed much more stable complexes with heparin than HepV, and collagen V bound to heparin/heparan sulfate with a higher affinity (in the nanomolar range) than HepV. Heat and chemical denaturation strongly decreased the binding, indicating that the triple helix plays a major role in stabilizing the interaction with heparin. Collagen V and HepV may play different roles in cell-matrix interactions and in matrix assembly or remodeling mediated by their specific interactions with heparan sulfate.Proteoglycans are widely distributed at the cell surface and in the extracellular matrix. They consist of a protein core to which one or more glycosaminoglycan side chains are covalently attached, conferring a strong negative charge on proteoglycans (1, 2). Interactions of proteoglycans with a number of matrix proteins, including collagens, are important in regulating cell behavior and fibril formation during development and pathophysiological events. Interactions with collagens can be dependent on the proteoglycan core protein or on the glycosaminoglycan chains. The heparan sulfate chain has various important biological properties and influences cell behavior through interactions with a variety of matrix proteins. Heparin binding sites have been identified and characterized in a wide range of matrix proteins, including collagens, but the structural requirements for heparan sulfate to bind these proteins are not fully understood.Collagen V, although a quantitatively minor component of connective tissues, plays a crucial role in matrix organization. Several isoforms of collagen V, including hybrid molecules containing collagen XI chains (3), occur in tissues, but the predominant molecular form is the heterotrimer (␣1(V)) 2 ␣2(V), whereas the ␣1(V)␣2(V)␣3(V) molecule and the (␣1(V)) 3 homotrimer are minor isoforms with a more restricted tissue distribution. Collagen V interacts with proteoglycans, which are widely distributed at the cell surface and in the extracellular matrix. It binds to the two small proteoglycans, decorin and biglycan, to the proteoglycan form of macrophage colony-stimulating factor (4), to the membrane chondroitin sulfate proteoglycan NG2 (5), and to syndecan-1 (6, 7). Binding to collagen V involves either the core protein or the glycosaminoglycan chains. Collagen V was shown to bind heparin through a 12-kDa fragment of the ␣1(V) chain referred to as HepV. Interestingly, we also showed that the recombinant HepV fragment supports heparin-dependent cell adhesion (8). The binding site for heparin is found in the ␣1 chain of collagen V, whereas the two other chains of collagen V, ␣2(V) and ␣3(V), do not bind to heparin. Sequence alignment of ␣ chains of collagens V and XI indicated that these two collagen types may use a common sequence motif to interact with heparin. This hypothesis was confirmed experimentally by others (9). The recombinant production of HepV in Escherichia coli has set the stage for identifying the hepa...

Myeloperoxidase-derived oxidants selectively disrupt the protein core of the heparan sulfate proteoglycan perlecan

“…2A) or collagen V binding (Supplementary Fig. 2B), demonstrating that the heparan sulfate sequences that bind these ligands (Guimond et al, 1993; Ricard-Blum et al, 2006) are resistant to modification by these oxidants. As well as maintaining their ability to bind FGF-2, the heparan sulfate chains of HOCl/HOBr-modified perlecan (oxidant/perlecan molar ratios of 100 and 1000) maintained their ability to stimulate proliferation of FGFR1c expressing cells in response to FGF-2 (Supplementary Fig.…”

The phosphorylation of vascular endothelial growth factor receptor-2 (VEGFR-2) by engineered surfaces with electrostatically or covalently immobilized VEGF

“…Covalently immobilized VEGF surfaces were generated using the same general approach except that heparin was modified with an amine reactive photoactivatable group that could be activated post VEGF immobilization (Figure 1B). Heparin was chosen because it has been previously shown to bind with VEGF through its heparin binding domain located at the C-terminus of the protein (4) and because it can also bind ECM proteins such as fibronectin (32, 33), collagen (34), vitronectin (35), and laminin (36). The binding of ECM proteins is essential to the study of VEGF/VEGFR-2 signaling cascades since the binding of cells through different integrin receptors as well as the binding of VEGF with the ECM molecules can modulate the signaling responses induced (33, 37).…”

Craniofacial cartilage morphogenesis requires zebrafish col11a1 activity

“…Consistent with previous observations in cho mice (Li et al, 1995), less proteoglycan aggregates were observed in the cartilage matrix of col11a1-morphants. Collagen XI α1 chain contains three different heparin binding sites that can bind heparan sulfate proteoglycans (Delacoux et al, 2000;Vaughan-Thomas et al, 2001;Blum et al, 2006). It is thus conceivable that the lack of collagen XI α1 alters retention of proteoglycans in cartilage tissues and, consequently affects interactions with other matrix components.…”