title: Constitutive release of alpha4 type V collagen N-terminal domain by Schwann cells and binding to cell surface and extracellular matrix heparan sulfate proteoglycans.
abstract: During peripheral nerve development, Schwann cells synthesize collagen type V molecules that contain alpha4(V) chains. This collagen subunit possesses an N-terminal domain (NTD) that contains a unique high affinity heparin binding site. The alpha4(V)-NTD is adhesive for Schwann cells and sensory neurons and is an excellent substrate for Schwann cell and axonal migration. Here we show that the alpha4(V)-NTD is released constitutively by Schwann cells both in culture and in vivo. In cultures of neonatal rat Schwann cells, alpha4(V)-NTD release is increased significantly by ascorbate treatment, which facilitates collagen post-translational modification and collagen trimer assembly. In peripheral nerve tissue, the alpha4(V)-NTD is localized to the region of the outer Schwann cell membrane and associated extracellular matrix. The released alpha4(V)-NTD binds to the cell surface and extracellular matrix heparan sulfate proteoglycans of Schwann cells. Pull-down assays and immunofluorescent staining showed that the major alpha4(V)-NTD-binding proteins are glypican-1 and perlecan. alpha4(V)-NTD binding occurs via a mechanism that requires the high affinity heparin binding site and that is blocked by soluble heparin, demonstrating that binding to proteoglycans is mediated by their heparan sulfate chains.
authors.affiliation: Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania 17822-2601, USA.
authors.forename: Katrina
authors.initials: K
authors.lastname: Rothblum
authors.forename: Richard C
authors.initials: RC
authors.lastname: Stahl
authors.forename: David J
authors.initials: DJ
authors.lastname: Carey
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D001369:Axons / Q000378:metabolism; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism*; D002465:Cell Movement; D002478:Cells, Cultured; D003094:Collagen / Q000737:chemistry; D024062:Collagen Type V / Q000737:chemistry*; D017077:Culture Media, Conditioned / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D000939:Epitopes / Q000737:chemistry; D005109:Extracellular Matrix / Q000378:metabolism*; D019812:Heparan Sulfate Proteoglycans / Q000737:chemistry*; D006493:Heparin / Q000737:chemistry; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011509:Proteoglycans / Q000737:chemistry; D051381:Rats; D012583:Schwann Cells / Q000378:metabolism*; D012584:Sciatic Nerve / Q000378:metabolism
chemical_list: D024062:Collagen Type V; D017077:Culture Media, Conditioned; D003902:Detergents; D000939:Epitopes; D019812:Heparan Sulfate Proteoglycans; D010455:Peptides; D011509:Proteoglycans; D006493:Heparin; D003094:Collagen; D001205:Ascorbic Acid