Proteoglycan secretory Components of Surface Epithelial cells in Postnatal Ferret Trachea* r Boat, M.D.; ~ Cheng, M.D.; B. Caterson, M.D.; B. johnstone, M.D.; and M. Uigh, M.D. cells of ferret tracheal epithelium secrete high Secretory molecular weight glycoconjugates (HMG) including
mucins and proteoglycans. Mucins are the predominant glycoconjugate released in the first postnatal days, but proteoglygan-like substances are released in increasing amounts as the epithelium matures (Biochem 1989; 28:9440). The cells oforigin ofthese secretory products are not known. We have used monoclonal antibodies (MAb) which recognize keratan sulfate (KS) and chondroitin sulfate (CS) to immunocytochemically examine the content of secretory granules in surface epithelial cells of newborn and mature ferret trachea sections.
8C2 8C2 4Dl 4Dl
HMG Recognized KS KS KS KS CS CS
Secretory Granule Staining
None None Keratanase None None Chondroitinase None
Of particular interest is the finding that 4DI and 4C3 recognize developmentally regulated proteoglycan epitopes. Appearance of CS during the first month of life is consistent with previous detection ofchondroitinase-susceptible HMG secretion by ferret tracheal explants after 2 weeks of postnatal life. Failure to diminish 4C3 binding with chondroitinase has been noted with CS-containing macromolecules in other tissues. Apical surfaces (glycocalyx) of epithelial cells also stained with these 3 MAb. We suggest that KS and CS are HMG secretory products of ferret tracheal surface epithelial cells and that the presence of specific proteoglycan epitopes in secretory granules can be used as markers ofepithelial cell maturation. The relationship of proteoglycan to mucin biosynthesis and secretion in single cells remains to be determined. *From the University of North Carolina, C~l Hill. Reprint requests: Dr. Boat, 500 Burnett Wnnack Building, CB 7220, Chapel Hill, NC 27599-7020
34th Annual Thomas L Petty Aspen Lung Conf8rence