首页 | 本学科首页   官方微博 | 高级检索  
   检索      


Epidermal growth factor enhancement of insulin-like growth factor-I-induced down-regulation of insulin-like growth factor I receptor in cultured placental trophoblastic cells.
Authors:B Bhaumick  R M Bala
Institution:Department of Medicine, University of Saskatchewan, Saskatoon, Canada.
Abstract:Epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) synergistically stimulate placental lactogen (hPL) secretion by placental cells. To understand the mechanism of actions we have investigated a possible heterologous regulatory effect of EGF and IGF-I on each other's receptors. Pretreatment of the cells with IGF-I had no effect on 125I]-EGF binding or the down-regulation of EGF receptor. Pretreatment of the cells with EGF, concomitantly with IGF-I, had no effect on 125I]-IGF-I binding but it augmented the IGF-I down-regulation of IGF-I receptor. The time required to initiate the IGF-I-induced down-regulation of IGF-I receptor was reduced by 4 h in the presence of EGF. IGF-I-down-regulated decreased (P less than 0.05) receptor numbers were further decreased (p less than 0.05) in the presence of EGF. These results suggested that the synergistic effect of EGF and IGF-I seen in hPL secretion by placental cells is not due to direct heterologous hormone-receptor interactive effects. However, the effects seen may be due to a differentiating effect of EGF sensitizing the cells for responsiveness to IGF-I.
Keywords:
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号