Schwann Cell Adhesion to a Novel Heparan Sulfate Binding Site in the N-terminal Domain of α4 Type V Collagen Is Mediated by Syndecan-3

Robert Erdman,Richard C Stahl,Katrina Rothblum,Michael A Chernousov,David J Carey

doi:10.1074/jbc.m111311200

Robert Erdman, Richard C Stahl + Show 3 more

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https://doi.org/10.1074/jbc.m111311200

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Abstract

Previously we reported that type V collagen synthesized by Schwann cells inhibits the outgrowth of axons from rat embryo dorsal root ganglion neurons but promotes Schwann cell migration (Chernousov, M. A., Stahl, R. C., and Carey, D. J. (2001) J. Neurosci. 21, 6125-6135). Analysis of Schwann cell adhesion and spreading on dishes coated with various type V collagen domains revealed that Schwann cells adhered effectively only to the non-collagenous N-terminal domain (NTD) of the alpha4(V) collagen chain. Schwann cell adhesion to alpha4(V)-NTD induced actin cytoskeleton assembly, tyrosine phosphorylation, and activation of the Erk1/Erk2 protein kinases. Adhesion to alpha4(V)-NTD is cell type-specific because rat fibroblasts failed to adhere to dishes coated with this polypeptide. Schwann cell adhesion and spreading on alpha4(V)-NTD was strongly inhibited by soluble heparin (IC(50) approximately 30 ng/ml) but not by chondroitin sulfate. Analysis of the heparin binding activities of a series of recombinant alpha4(V)-NTD fragments and deletion mutants identified a highly basic region (not present in other type V collagen NTD) as the site responsible for high affinity heparin binding. Schwann cells adhered poorly to dishes coated with alpha4(V)-NTD that lacked the heparin binding site and failed to spread or assemble organized actin-cytoskeletal structures. Soluble alpha4(V)-NTD polypeptide that contained the heparin binding site inhibited spreading of Schwann cells on dishes coated with alpha4(V)-NTD. Affinity chromatography of Schwann cell detergent extracts on a column of immobilized alpha4(V)-NTD resulted in the isolation of syndecan-3, a transmembrane heparan sulfate proteoglycan. Together, these results suggest that Schwann cells bind to collagen type V via syndecan-3-dependent binding to a novel high affinity heparin binding site in the alpha4(V)-NTD.

Highlights

Interactions of Schwann cells and neurons with extracellular matrix (ECM)1 are critical for many aspects of peripheral nervous system development and function
Affinity chromatography of Schwann cell detergent extracts on a column of immobilized ␣4(V)-N-terminal domain (NTD) resulted in the isolation of syndecan-3, a transmembrane heparan sulfate proteoglycan. These results suggest that Schwann cells bind to collagen type V via syndecan-3-dependent binding to a novel high affinity heparin binding site in the ␣4(V)-NTD
In addition to the collagen triple helical domains, the ␣1(V) and ␣4(V) subunits contain non-collagenous N-terminal domains (NTD) that are retained in at least some mature collagen trimers secreted by Schwann cells. ␣4(V) collagen expression is reduced in terminally differentiated Schwann cells but is induced in response to nerve injury [13]

Summary

Introduction

Interactions of Schwann cells and neurons with extracellular matrix (ECM) are critical for many aspects of peripheral nervous system development and function. Cell-ECM interactions regulate such processes as Schwann cell and axonal migration [1,2,3] and Schwann cell terminal differentiation [4, 5]. Prior to the onset of myelin formation peripheral nerve ECM is comprised mainly of fibrillar matrix structures that contain collagen types I and V and fibronectin [10]. This is a highly dynamic period of nerve development that is characterized by axonal and Schwann cell migration and Schwann cell proliferation. Schwann cell collagen type V promotes Schwann cell migration via a mechanism that appears to depend on an interaction with the non-collagenous NTD.

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