ANALYSIS OF PROTEOGLYCAN EXPRESSION IN DEVELOPING CHICKEN BRAIN - CHARACTERIZATION OF A HEPARAN-SULFATE PROTEOGLYCAN THAT INTERACTS WITH THE NEURAL CELL-ADHESION MOLECULE

In the present study we have characterized the major proteoglycans of chick brain, focusing on their pattern of expression in development an d on identifying the heparan sulfate proteoglycan (HSPG) that binds to the neural cell adhesion molecule (NCAM), The major chondroitin sulfa te proteoglycans (CSPG) are a heterogeneous group of molecules with an average MW of 450 kDa. Protein core analysis reveals multiple protein cores between 100 and 350 kDa. The HSPGs are somewhat smaller, with a n average MW of 350 kDa, and the major brain HSPG possesses a 250 kDa protein core, During development the relative percentage of HSPG decre ases from approximately 50% of total sulfate-labeled PG at E6 to 25% b y E10. In order to begin to characterize the HSPG that interacts with NCAM, we initially used an antiserum produced against a HSPG which was previously shown to copurify with NCAM (Cole and Burg: Exp Cell Res 1 82:44-60, 1989). This antiserum immunoprecipitated a HSPG core protein of 250 kDa, corresponding to the major HSPG of chick brain, We also s how that the major brain HSPG binds to a synthetic peptide that encode s the heparan sulfate-binding domain of NCAM, and that monoclonal anti bodies to a recently identified chick retinal HSPG recognize this NCAM -binding HSPG, This HSPG was immunopurified from E10 chick brain using the 6D2 monoclonal antibody, and has been shown to bind an affinity c olumn containing the heparan sulfate-binding peptide of NCAM, Consiste nt with its ability to bind NCAM, we show that the intact 6D2 HSPG inh ibits cell adhesion to a HBD peptide substratum, and also binds chick brain cells when employed as a substratum. (C) 1995 Wiley-Liss, Inc.