Epidermal-growth-factor-induced formation of inositol phosphates in human A431 cells. Differences from the effect of bradykinin.
Epidermal-growth-factor-induced formation of inositol phosphates in human A431 cells. Differences from the effect of bradykinin.
复制标题
表皮生长因子诱导人 A431 细胞中磷酸肌醇的形成。
作者：
B. Tilly;P. V. van Paridon;I. Verlaan;S. D. de Laat;W. Moolenaar
在人表皮样癌细胞A431中，表皮生长因子（EGF）迅速刺激肌醇磷脂的分解，并提高细胞质游离[Ca 2 +]。在本文中，我们研究了EGF对磷酸肌醇代谢的作用，并将其与先前描述的缓激肽对相同细胞系统的作用进行了比较[蒂利，货车Paridon，Verlaan，维尔茨，de Laat和Moolenaar（1987）Biochem.J.244，129-135]。在用[3 H]肌醇预标记的细胞中，EGF缓慢但持续地（至少30分钟）刺激[3 H]肌醇磷酸的形成，而缓激肽引起肌醇磷酸的立即但短暂的释放，仅持续几分钟。EGF的作用是缓激肽刺激的附加物，不需要细胞外Ca 2+。相反，由Ca 2 +-离子载体A23187诱导的磷酸肌醇形成对外部Ca 2+有绝对的需求。用12-O-十四酰基佛波醇13-乙酸酯处理细胞完全消除了对EGF和次优剂量的缓激肽的反应，表明蛋白激酶C的负反馈功能。用百日咳毒素预处理细胞对EGF或缓激肽诱导的磷酸肌醇形成没有影响。与缓激肽不同，EGF刺激很少的肌醇1，4，5-三磷酸的积累，仅从细胞内储存中释放少量且相当可变的Ca 2+。EGF迅速但短暂地增加肌醇1，3，4-三磷酸和1，3，4，5-四磷酸，但效果比缓激肽小得多。此外，EGF增加肌醇单磷酸和二磷酸。在加入EGF后10分钟，与其他肌醇磷酸盐不同，肌醇一磷酸盐仍在增加。它的结论是，EGF依赖的刺激模式是不同的缓激肽刺激的A431细胞中观察到的，这表明有独立的肌醇脂质水解的机制。
In human A431 epidermoid carcinoma cells, epidermal growth factor (EGF) rapidly stimulates the breakdown of inositol phospholipids and raises cytoplasmic free [Ca2+]. In this paper, we investigate the action of EGF on inositol phosphate metabolism, and we compare it with the previously described effects of bradykinin on the same cell system [Tilly, van Paridon, Verlaan, Wirtz, de Laat & Moolenaar (1987) Biochem. J. 244, 129-135]. In cells prelabelled with [3H]inositol, EGF slowly but persistently (for at least 30 min) stimulates the formation of [3H]inositol phosphates, whereas bradykinin causes an immediate but transient release of inositol phosphates, which lasts for only a few minutes. The EGF effect is additive to bradykinin stimulation and does not require extracellular Ca2+. In contrast, inositol phosphate formation induced by Ca2+-ionophore A23187 has an absolute requirement for external Ca2+. Treatment of the cells with 12-O-tetradecanoylphorbol 13-acetate completely abolishes the response to EGF and to sub-optimal doses of bradykinin, suggesting a negative-feedback function of protein kinase C. Pretreatment of the cells with pertussis toxin has no effect on inositol phosphate formation induced by either EGF or bradykinin. Unlike bradykinin, EGF stimulates very little accumulation of inositol 1,4,5-trisphosphate, with only a small and rather variable release of Ca2+ from intracellular stores. EGF rapidly but transiently increases inositol 1,3,4-trisphosphate and 1,3,4,5-tetrakisphosphate, but the effects are much smaller than those of bradykinin. In addition, EGF increases both inositol mono- and bis-phosphate. At 10 min after EGF addition, inositol monophosphate, unlike the other inositol phosphates, is still increasing. It is concluded that the EGF-dependent pattern of stimulation is different from that observed in bradykinin-stimulated A431 cells, suggesting that there are separate mechanisms of inositol-lipid hydrolysis involved.