Inhibition by tunicamycin of mucin synthesis, not morphological changes, in epidermis during retinol-induced mucous metaplasia of chick embryonic cultured skin

摘要

abstract_textpBackground: Our previous studies have shown that epidermal mucous metaplasia of chick embryonic skin can be induced by culture in medium containing 20 mu M retinol for only 8 hr and then in a chemically defined medium without retinol for 2 days and that retinol primarily affects the dermal cells, which then transform the epithelial cells into mucus-secreting cells./ppMethods: Tarsometatarsal skin of 13-day-old chick embryo was cultured with 20 mu M retinol for 1 day and then without the vitamin but with 0.1 mu g/ml tunicamycin for 5 days, Effect of tunicamycin on epidermal mucous metaplasia was studied biochemically and morphologically./ppResults: Tunicamycin, which prevents the formation of N-glycans and inhibits maturation or morphological organization of various epithelial cells, irreversibly inhibited the synthesis of sulfated glycoproteins (O-glycans, mucin) in the epidermis only when applied to retinol-pretreated skin, Microvilli on the surface of the cells were well developed, but mucous granules surrounded by a limiting membrane were not observed in the upper cell layer of the epidermis, and many vesicles without electron-dense materials (mucin) and dilated rough endoplasmic reticulum were seen in the intermediate cell layers of the epidermis, When recombinants of 13-day-old normal epidermis and cultured dermis, which had been treated with retinol for 24 hr and with only tunicamycin for 2 days, were cultured without the antibiotic for 5 days, epidermal mucous metaplasia was induced./ppConclusion: These results suggest that tunicamycin did not prevent morphological changes induced by retinol but inhibited mucin synthesis by a direct action on the epidermis of retinol-pretreated skin, Because in some cell-line mucin precursors contain high mannose N-linked oligosaccharides side chains, tunicamycin may have inhibited mucin synthesis, Interaction between epidermal basal cells and retinol-pretreated dermal fibroblasts is prerequisite for epidermal mucous metaplasia, Thus, the present study suggests that N-linked protein glycosylation is not required for this interaction. (C) 1996 Wiley-Liss, Inc./p/abstract_text