Endothelin-1 stimulates c-fos mRNA expression and acts as a modulator on cell proliferation of rat FRTL5 thyroid cells. |
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Authors: | M Miyakawa T Tsushima O Isozaki H Demura K Shizume M Arai |
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Affiliation: | Department of Medicine, Tokyo Women's Medical College, Japan. |
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Abstract: | In FRTL5 thyroid cells, endothelin (ET)-1 alone had no effect on DNA synthesis but caused a transient increase in c-fos mRNA levels and stimulated IGF-I induced DNA synthesis and cell proliferation. By contrast, ET-1 inhibited the stimulatory effects of TSH actions on DNA synthesis, cell proliferation and c-AMP production. 8-Bromo-cAMP-induced DNA synthesis was also inhibited by ET-1, suggesting that ET-1 exerts its inhibitory effects at step(s) involving cAMP production and post cAMP pathway. ET-1-induced suppression of TSH actions were reversed by a C-kinase inhibitor, H-7. These results suggest that the effect of ET on functions of FRTL5 cells is, at least, in part mediated by C-kinase dependent pathway. |
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