A NOVEL LAMININ-BINDING FORM OF SYNDECAN-1 (CELL-SURFACE PROTEOGLYCAN) PRODUCED BY SYNDECAN-1 CDNA-TRANSFECTED NIH-3T3 CELLS

Syndecan-1, a cell surface proteoglycan, binds many extracellular matr ix components via its heparan sulfate side chains. In previous studies syndecan-1 has failed to bind laminin, although both syndecan-1 and l aminin are expressed at sites of early matrix accumulation, like in ba sement membranes of epithelial-mesenchymal boundaries and in condensin g mesenchymes during embryonic development. In order to study whether syndecan-1 regulates the adhesion of mesenchymal cells to laminin, syn decan-1 was expressed in NIH-3T3 cells by transfection. Syndecan-1-tra nsfected cells showed increased binding to laminin in comparison to co ntrol transfected cells. We then compared the properties of syndecan-1 isolated from transfected NIH-3T3 cells and from NMuMG mammary epithe lial cells. In solid-phase binding assays, syndecan-1 from NIH-3T3 cel ls, but not NMuMG cells, bound to laminin. NIH-3T3-derived syndecan co ntained more chondroitin sulfate than NMuMG-derived syndecan-1, and ou r results revealed that both heparan sulfate and chondroitin sulfate m ediate syndecan-1 binding to laminin. E3 domain revealed highest bindi ng for syndecan-1 among the elastase-derived fragments of laminin. The se results suggest that induction of syndecan-1 in mesenchymal cells m ay be involved in cellular recognition of laminin during developmental processes. (C) 1994 Academic Press, Inc.