IDENTIFICATION OF DECORIN PROTEOGLYCAN IN BOVINE TRACHEAL SEROUS CELLS IN CULTURE AND LOCALIZATION OF DECORIN MESSENGER-RNA IN-SITU

Bovine tracheal submucosal gland serous cells in culture synthesize an d secrete proteoglycans and not mucin glycoconjugates. We are interest ed in the characterization and role of these proteoglycans in airway s ecretions. The major [S-35]methionine-labeled proteoglycan present is identified as the small chondroitin/dermatan sulfate proteoglycan deco rin (PG II. PG40). Consistent with its identity as decorin this proteo glycan showed average apparent molecular weights of 75000 to 130000 wi th a core protein of an average, M(r) of about 40000 and with glycosam inoglycan chains sensitive to chondroitinase ABC lyase of an average M (r) of about 25000. These data were obtained from gel chromatographic and SDS-PAGE analyses. Northern blot analysis and partial amino acid s equencing of the purified protein further confirmed its identity as de corin. In situ hybridization studies using a decorin riboprobe reveale d no expression of decorin in the surface epithelium and only low leve ls of expression in submucosal gland epithelial cells of bovine trache al tissue. However, high levels of expression were localized to cells which are peripheral to tracheal submucosal gland epithelial cells and which contact with the extracellular matrix.