Thyrotropin modulates EGF receptor function in porcine thyroid follicle cells.
Porcine thyroid follicle cells in monolayer cultures were shown to contain one single class of high-affinity EGF receptors with Kd = 4.5 X 10(-10) M and approximately 20 000-25 000 receptors per cell. Suspension cultures of aggregated follicle cells, exposed to TSH for 3 days, showed a 3-fold increase in [125I]EGF binding. Scatchard analysis demonstrated that this was due to an increase in receptor number. Other cAMP-elevating agents (cholera toxin, dibutyryl cAMP, forskolin) induced a similar effect. In suspension cultures, preincubation with TSH or cholera toxin for 2 days reduced the subsequent [3H]thymidine incorporation. This inhibition was overcome by a low concentration of EGF (0.1 ng/ml). At higher concentrations of EGF (1-10 ng/ml) the incorporation of [3H]thymidine was potentiated 2-3-fold in cultures preexposed to TSH or cholera toxin. The results demonstrate the presence of a high-affinity EGF receptor in porcine thyroid follicle cells. Receptor expression, as well as responsiveness to the mitogenic action of EGF, is modulated in vitro by TSH, through a cAMP-dependent process.
Westermark
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K
Karlsson
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FA
Westermark
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B
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D005576:Colforsin; D000242:Cyclic AMP / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D004224:Diterpenes / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors; D011956:Receptors, Cell Surface / Q000187:drug effects*; D013552:Swine; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology*
D004224:Diterpenes; D011956:Receptors, Cell Surface; D005576:Colforsin; D004815:Epidermal Growth Factor; D003994:Bucladesine; D013972:Thyrotropin; D002772:Cholera Toxin; D000242:Cyclic AMP; D066246:ErbB Receptors