Némoz-Gaillard E, Cordier-Bussat M, Filloux C, Cuber J C, Van Obberghen E, Chayvialle J A, Abello J
INSERM Unité 45, Hôpital Edouard-Herriot, Pavillon Hbis, 69437 Lyon Cédex 3, France.
Biochem J. 1998 Apr 1;331 ( Pt 1)(Pt 1):129-35. doi: 10.1042/bj3310129.
Bombesin has been reported to stimulate cholecystokinin (CCK) secretion from rat duodeno-jejunal I-cells. Bombesin was shown to activate mitogen-activated protein kinases (MAPKs) in cell types such as Swiss 3T3 fibroblasts and rat pancreatic acinar cells. No information is available on whether MAPK is activated in intestinal endocrine cells upon bombesin stimulation. This was studied by using the CCK-producing enteroendocrine cell line STC-1. Bombesin stimulated markedly and transiently both p42(MAPK) and p44(MAPK), with a maximum at 2 min, and a decrease to basal levels within 10 min. As expected, bombesin stimulated MAPK kinase 1 (MEK-1) activity. Activation of protein kinase C (PKC) with PMA also stimulated p42(MAPK), p44(MAPK) and MEK-1. Treatment of cells with PD 098059 (at 10 microM or 30 microM), which selectively inhibits MEK phosphorylation, blocked bombesin-induced p42(MAPK) and p44(MAPK) activation for at least 90 min. However, PD 098059 inhibited bombesin- and PMA-stimulated CCK secretion during the first 15 min, but failed to significantly reduce CCK release at later times. Inhibition of PKC with staurosporine, or PKC down-regulation by prolonged treatment with PMA, both drastically decreased MEK-1, p42(MAPK) and p44(MAPK) activation upon bombesin stimulation. Additionally, PKC activation appeared to be required for both MAPK-dependent (early) and -independent (late) CCK responses to bombesin. It is concluded that the early CCK secretory response of STC-1 cells to bombesin involves MAPK pathway activation through a PKC-dependent mechanism, whereas the late phase of bombesin-induced CCK secretion, that also requires PKC, appears to result from a MAPK-independent process.
据报道，蛙皮素可刺激大鼠十二指肠 - 空肠I细胞分泌胆囊收缩素（CCK）。蛙皮素已被证明能在诸如瑞士3T3成纤维细胞和大鼠胰腺腺泡细胞等细胞类型中激活丝裂原活化蛋白激酶（MAPK）。关于蛙皮素刺激后肠道内分泌细胞中MAPK是否被激活尚无相关信息。本研究使用产生CCK的肠内分泌细胞系STC - 1对此进行了探究。蛙皮素能显著且短暂地刺激p42（MAPK）和p44（MAPK），在2分钟时达到最大值，并在10分钟内降至基础水平。正如预期的那样，蛙皮素刺激了MAPK激酶1（MEK - 1）的活性。用佛波酯（PMA）激活蛋白激酶C（PKC）也能刺激p42（MAPK）、p44（MAPK）和MEK - 1。用PD 098059（10 microM或30 microM）处理细胞，该药物能选择性抑制MEK磷酸化，可阻断蛙皮素诱导的p42（MAPK）和p44（MAPK）激活至少90分钟。然而，PD 098059在最初15分钟内抑制了蛙皮素和PMA刺激的CCK分泌，但在随后的时间里未能显著降低CCK的释放。用星形孢菌素抑制PKC，或通过长时间用PMA处理下调PKC，均显著降低了蛙皮素刺激后MEK - 1、p42（MAPK）和p44（MAPK）的激活。此外，PKC激活似乎是STC - 1细胞对蛙皮素的MAPK依赖性（早期）和非依赖性（晚期）CCK反应所必需的。研究得出结论，STC - 1细胞对蛙皮素的早期CCK分泌反应涉及通过PKC依赖性机制激活MAPK途径，而蛙皮素诱导的CCK分泌的晚期阶段，同样需要PKC，似乎是由MAPK非依赖性过程导致的。
