Inhibition by epidermal growth factor of glucocorticoid-induced epidermal alpha-type keratinization of chick embryonic skin cultured in the presence of delipidized fetal calf serum.
When a 13-day-old chick embryonic tarsometatarsal skin was cultured for 4 days in medium containing hydrocortisone (20 nM) and 5% delipidized fetal calf serum (FCS), epidermal growth factor (EGF, 100 ng/ml) decreased epidermal DNA content 42% and inhibited epidermal DNA synthesis 87%. Tonofilament bundles within the basal and intermediate cells of the EGF-treated epidermis were not as conspicuous as those in the glucocorticoid-induced keratinized epidermis, and the upper region of the EGF-treated epidermis did not form either the filament bundles or the electron-dense amorphous masses seen in the cytoplasm of the glucocorticoid-induced keratinized layer. EGF stimulated degradation of glucocorticoid-induced alpha-keratin. Furthermore, EGF caused a twofold increase in glucocorticoid-induced epidermal transglutaminase activity and in the amount of epidermal glucocorticoid receptor. In the absence of FCS, however, EGF did not inhibit steroid-induced alpha-type keratinization and did not affect either steroid-induced epidermal transglutaminase activity or amount of epidermal glucocorticoid receptor. Hence, the effect of EGF on glucocorticoid-induced epidermal transglutaminase activity was observed only in the presence of delipidized FCS and might be supported by an increase in the amount of glucocorticoid receptor.
D000818:Animals; D002642:Chick Embryo; D003593:Cytoplasm / Q000648:ultrastructure; D004247:DNA / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D004817:Epidermis / Q000378:metabolism; D066246:ErbB Receptors / Q000187:drug effects / Q000378:metabolism; D005312:Fetal Blood; D005938:Glucocorticoids / Q000494:pharmacology*; D005998:Glycine / Q000378:metabolism; D006854:Hydrocortisone / Q000494:pharmacology; D007633:Keratins / Q000096:biosynthesis*; D007700:Kinetics; D008055:Lipids / Q000097:blood; D008854:Microscopy, Electron; D009924:Organ Culture Techniques; D011506:Proteins / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012867:Skin / Q000196:embryology* / Q000378:metabolism / Q000648:ultrastructure; D011503:Transglutaminases / Q000378:metabolism
D005938:Glucocorticoids; D008055:Lipids; D011506:Proteins; D004815:Epidermal Growth Factor; D012313:RNA; D007633:Keratins; D004247:DNA; D011503:Transglutaminases; D066246:ErbB Receptors; D005998:Glycine; D006854:Hydrocortisone