scholarly journals Differential protein phosphorylation in induction of thyroid cell proliferation by thyrotropin, epidermal growth factor, or phorbol ester.

1988 ◽  
Vol 8 (6) ◽  
pp. 2494-2503 ◽  
Author(s):  
L Contor ◽  
F Lamy ◽  
R Lecocq ◽  
P P Roger ◽  
J E Dumont
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cyclic Amp ◽  
Protein Phosphorylation ◽  
Primary Cultures ◽  
Tumor Promoter ◽  
Thyroid Cell ◽  
Differential Protein ◽  
Phosphorylated Proteins ◽  
Epidermal Growth

Protein phosphorylation was studied in primary cultures of thyroid epithelial cells after the addition of different mitogens: thyrotropin (TSH) acting through cyclic AMP, epidermal growth factor (EGF), or 12-O-tetradecanoylphorbol-13-acetate (TPA). EGF or TPA increased the phosphorylation of five common polypeptides. Among these, two 42-kilodalton proteins contained phosphotyrosine and phosphoserine with or without phosphothreonine. Their characteristics suggested that they are similar to the two 42-kilodalton target proteins for tyrosine protein phosphorylation demonstrated in fibroblasts in response to mitogens. No common phosphorylated proteins were detected in TSH-treated cells and in EGF- or TPA-treated cells. The differences in the protein phosphorylation patterns in response to TSH, EGF, and TPA suggested that the newly emerging cyclic AMP-mediated mitogenic pathway is distinct from the better known growth factor- and tumor promoter-induced pathways.

Differential protein phosphorylation in induction of thyroid cell proliferation by thyrotropin, epidermal growth factor, or phorbol ester

1988 ◽  
Vol 8 (6) ◽  
pp. 2494-2503
Author(s):  
L Contor ◽  
F Lamy ◽  
R Lecocq ◽  
P P Roger ◽  
J E Dumont
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cyclic Amp ◽  
Protein Phosphorylation ◽  
Primary Cultures ◽  
Tumor Promoter ◽  
Thyroid Cell ◽  
Differential Protein ◽  
Phosphorylated Proteins ◽  
Epidermal Growth

Protein phosphorylation was studied in primary cultures of thyroid epithelial cells after the addition of different mitogens: thyrotropin (TSH) acting through cyclic AMP, epidermal growth factor (EGF), or 12-O-tetradecanoylphorbol-13-acetate (TPA). EGF or TPA increased the phosphorylation of five common polypeptides. Among these, two 42-kilodalton proteins contained phosphotyrosine and phosphoserine with or without phosphothreonine. Their characteristics suggested that they are similar to the two 42-kilodalton target proteins for tyrosine protein phosphorylation demonstrated in fibroblasts in response to mitogens. No common phosphorylated proteins were detected in TSH-treated cells and in EGF- or TPA-treated cells. The differences in the protein phosphorylation patterns in response to TSH, EGF, and TPA suggested that the newly emerging cyclic AMP-mediated mitogenic pathway is distinct from the better known growth factor- and tumor promoter-induced pathways.

Effect of thyrotrophin on epidermal growth factor receptors in monolayer cultures of porcine thyroid cells

1987 ◽  
Vol 114 (2) ◽  
pp. 179-184 ◽  
Author(s):  
S. Atkinson ◽  
P. Kendall-Taylor
Keyword(s):  
Protein Synthesis ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cyclic Amp ◽  
Thyroid Hormones ◽  
Primary Cultures ◽  
Protein Synthesis Inhibitor ◽  
Scatchard Analysis ◽  
Thyroid Cells ◽  
Epidermal Growth

ABSTRACT Primary cultures of porcine thyroid cells, grown as monolayers, showed saturable binding of epidermal growth factor (EGF). Scatchard analysis resolved the binding to a high-affinity/low-capacity site (dissociation constant = 0·17 nmol/l, maximal binding capacity = 1·67 pmol/106 cells) and a low-affinity/high-capacity site. Preincubation of thyroid monolayers with TSH for 3 days caused an increase in binding of 125I-labelled EGF due to an increase in the number of receptors, with the binding affinity unchanged. This effect was dose-dependent within the range of TSH concentrations 0·01–100 mu/l. The same effect was seen with dibutyryl cyclic AMP (10–1000 μmol/l). When the protein synthesis inhibitor cycloheximide was included in the TSH preincubation, the increase in EGF binding was abolished. The TSH effect on EGF binding was not mediated by thyroid hormones, since neither thyroxine (T4) nor tri-iodothyronine (T3) at 01 nmol/l–10 μmol/l could mimic the effect of TSH, nor could antisera to T3 or T4 neutralize the effect of TSH. The concentration of extracellular iodide (10 nmol/l–10 mmol/l) had no effect on the binding of 125I-labelled EGF. The results demonstrate that TSH increases the number of receptor sites for binding of EGF to thyroid monolayers in vitro. This effect is dependent upon protein synthesis and is mediated by cyclic AMP but not by thyroid hormones or iodide. This effect on binding of EGF may contribute to the trophic action of TSH. J. Endocr. (1987) 114, 179–184

Epidermal growth factor (EGF) inhibits the secretomotor response of the thyroid: effects of EGF on radioiodine turnover and fluid transport in cultured porcine thyroid cells

1991 ◽  
Vol 128 (2) ◽  
pp. 213-218 ◽  
Author(s):  
J. R. Bourke ◽  
S. Murdoch ◽  
S. W. Manley ◽  
T. Matainaho ◽  
G. J. Huxham ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cyclic Amp ◽  
Fluid Transport ◽  
Prostaglandin E ◽  
Thyroid Cell ◽  
Ionophore A23187 ◽  
Maximal Effect ◽  
Thyroid Cells ◽  
Epidermal Growth

ABSTRACT Thyrotrophin (4-256 μU/ml) promoted an increase in the rate of release of radioiodine from the organic iodine pool of cultured porcine thyroid cells in follicular formations. This action of TSH was antagonized by low concentrations of epidermal growth factor (EGF; 0·1–5 nmol/l). The maximal effect of EGF was reached by 0·5 nmol/l. EGF (0·5–5 nmol/l) also inhibited the stimulatory effect of 8-chloro cyclic AMP (0·06–1·0 nmol/l) on radioiodine turnover. Exposure of thyroid cultures to media with a calcium concentration of 17·7 μmol/l (1% of normal) resulted in a very marked increase in the rate of release of radioiodine. The effect of TSH in low-calcium media was to inhibit the increased release of radioiodine, and EGF (0·5 nmol/l) antagonized this inhibitory effect of TSH. The calcium ionophore, A23187, stimulated radioiodine release in a dose-dependent fashion, and EGF (1·7 nmol/l) inhibited this response. Fluid transport in thyroid monolayers was stimulated by prostaglandin E2 (PGE2; 1 μmol/l). EGF (5 nmol/l) also stimulated fluid transport, but antagonized the effect of PGE2 added subsequently. It was concluded that EGF exerted acute antagonistic effects on thyroid cell responses in vitro to cyclic AMP and agents promoting accumulation of cyclic AMP in time-frames too short for these inhibitory effects to be attributable to the dedifferentiative effect of the growth factor. Journal of Endocrinology (1991) 128, 213–218

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