title: Tunicamycin blocks the emergence and maintenance of insulin receptors on mitogen-activated human T lymphocytes.
abstract: Treatment of phytohemagglutinin (PHA) activated human T lymphocytes with tunicamycin, an antibiotic that specifically inhibits asparagine-linked N-glycosylation of proteins, totally blocked the normal emergence of insulin receptors on these lymphocytes and their cellular proliferation during culture in a dose-dependent manner. Carbohydrate incorporation into protein was inhibited 82% by 0.5 microgram/mL while leucine incorporation was unaffected. Tunicamycin exposure of activated T lymphocytes, which had acquired insulin receptors during culture, reduced cellular insulin binding by 35% to 84% and reduced PHA binding to 40% of control levels within 24 hours. Scatchard analysis revealed decreases in insulin binding capacity but not affinity. Similar treatment with cycloheximide only decreased insulin binding by 12%. These findings suggest N-glycosylation of proteins is a necessary biochemical event (1) for the emergence and maintenance of insulin receptors on mitogen activated T lymphocytes, and (2) for mitogen activated T lymphocytes to undergo cell division.
mesh_terms: D000328:Adult; D001216:Asparagine / Q000037:antagonists & inhibitors; D005944:Glucosamine / Q000031:analogs & derivatives*; D006801:Humans; D066298:In Vitro Techniques; D008213:Lymphocyte Activation / Q000187:drug effects; D010835:Phytohemagglutinins / Q000378:metabolism / Q000494:pharmacology*; D011972:Receptor, Insulin / Q000187:drug effects*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D014415:Tunicamycin / Q000494:pharmacology*
chemical_list: D010835:Phytohemagglutinins; D014415:Tunicamycin; D001216:Asparagine; D011972:Receptor, Insulin; D005944:Glucosamine