The proteoglycan lectin domain binds sulfated cell surface glycolipids andpromotes cell adhesion

The lecticans are a group of chondroitin sulfate proteoglycans characterize d by the presence of C-type lectin domains. Despite the suggestion that the ir lectin domains interact with carbohydrate ligands, the identity of such ligands has not been elucidated. We previously showed that brevican, a nerv ous system-specific lectican, binds the surface of B28 glial cells (Yamada, H., Fredette, B., Shitara, K., Hagihara, K., Miura, R., Ranscht, B., Stall cup, W, B., and Yamaguchi, Y. (1997) J. Neurosci, 17, 7784-7795), In this p aper, we demonstrate that two classes of sulfated glycolipids, sulfatides a nd HNK-1-reactive sulfoglucuronylglycolipids (SGGLs), act as cell surface r eceptors for brevican. The lectin domain of brevican binds sulfatides and S GGLs in a calcium-dependent manner as expected of a C-type lectin domain. I ntact, full-length brevican also binds both sulfatides and SGGLs. The lecti n domain immobilized as a substrate supports adhesion of cells expressing S GGLs or sulfatides, which was inhibited by monoclonal antibodies against th ese glycolipids or by treatment of the substrate with SGGLs or sulfatides, Our findings demonstrate that the interaction between the lectin domains of lecticans and sulfated glycolipids comprises a novel cell substrate recogn ition system, and suggest that lecticans in extracellular matrices serve as substrate for adhesion and migration of cells expressing these glycolipids in vivo.