Schwann Cells Secrete a Novel Collagen-like Adhesive Protein That Binds N-Syndecan

doi:10.1074/jbc.271.23.13844

Schwann Cells Secrete a Novel Collagen-like Adhesive Protein That Binds N-Syndecan*

From the Sigfried and Janet Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania 17822

^‡ To whom correspondence should be addressed:
Sigfried and Janet Weis Center for Research, Geisinger Clinic, 26-13, 100 North Academy Ave., Danville, PA 17822.
Tel.: 717-271-6678; Fax: 717-271-6701.

Abstract

A heparin-binding glycoprotein was purified from conditioned medium of cultured rat Schwann cells. The protein, p200, which has an apparent molecular mass of approximately 200 kDa, was identified by its ability to bind the cell surface heparan sulfate proteoglycan N-syndecan (syndecan-3) in a membrane overlay assay. Soluble heparin but not chondroitin sulfate inhibited the binding, suggesting the involvement of heparan sulfate chains of proteoglycan in the interaction. Purified p200 promoted the attachment and spreading of Schwann cells. Adhesion to p200 was blocked by heparin, suggesting that heparan sulfate proteoglycans are cell surface receptors for p200. The tissue distribution of p200 was determined by immunoblot analysis with anti-p200 antibodies. Among neonatal rat tissues examined p200 was detected only in sciatic nerve and, at lower levels, in skeletal muscle. p200 expression in sciatic nerve was detectable only during the first 2-3 weeks of postnatal development and was not detected in adult rats. Immunofluorescent staining of rat sciatic nerve showed that p200 was localized in the extracellular matrix surrounding individual Schwann cells-axon units. Two tryptic peptides from p200 were purified and sequenced. These contained multiple GXX collagen-like repeats. Bacterial collagenase digestion of p200 produced a product with an apparent molecular mass of approximately 90 kDa. These data suggest that Schwann cells secrete an apparently novel collagen-like adhesive protein that interacts with cells through cell surface heparan sulfate proteoglycans.

Footnotes

↵* This work is supported by National Institutes of Health Grant NS21925. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

ECM

extracellular matrix

DMEM

Dulbecco's modified Eagle's medium

PMSF

phenylmethlsulfonyl fluoride

BSA

bovine serum albumin

PBS

phosphate-buffered saline.
↵² D. J. Carey and L. J. Showalter, manuscript in preparation.
- Received September 18, 1995.
- Revision received February 6, 1996.