Epithelial sheet movement: effects of tunicamycin on migration and glycoprotein synthesis.
Corneas with central epithelial wounds, 3 mm in diameter, were organ cultured in the presence of tunicamycin (TM) (1 microgram/ml), an antibiotic that inhibits glycosylation of asparagine-linked glycoproteins. Compared with control corneas, which healed in 22 hr, corneas cultured in the presence of TM for the entire culture time or for only the first 6 hr displayed a progressively slower epithelial healing rate that essentially dropped to zero by 24 hr of culture time. At 24 hr, approximately 75% of the wound was covered. After repeated washings with TM-free culture media (6X, 10 min each), this effect could consistently be reversed in corneas exposed to TM for 6 hr. Incorporation of [3H]glucosamine into trichloroacetic acid-precipitable proteins of migrating epithelial sheets was reduced to 14% that of controls after 12 hr of culture with TM, whereas [14C]leucine incorporation was not significantly affected. The decreased glycosylation was reflected on the cell surface after 12 and 20 hr culture in the presence of TM: apical cell membranes of the first six cells of the leading edge of the migrating sheet bound significantly fewer ferritin-concanavalin A particles per micrometer of membrane than did controls. These results indicate that synthesis of asparagine-linked glycoproteins is required for continued migration of corneal epithelial sheets. The asparagine-linked glycoproteins that are required for migration probably include cell-surface glycoproteins.
D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D003208:Concanavalin A; D003315:Cornea / Q000166:cytology* / Q000187:drug effects; D046508:Culture Techniques; D004848:Epithelium / Q000502:physiology*; D005944:Glucosamine / Q000031:analogs & derivatives*; D006023:Glycoproteins / Q000096:biosynthesis / Q000502:physiology*; D008297:Male; D008855:Microscopy, Electron, Scanning; D014176:Protein Biosynthesis; D051381:Rats; D014415:Tunicamycin / Q000494:pharmacology*; D014945:Wound Healing
D006023:Glycoproteins; D003208:Concanavalin A; D014415:Tunicamycin; D005944:Glucosamine