Huang Y, Hui D Y
Department of Pathology and Laboratory Medicine, University of Cincinnati, Ohio 45267-0529.
Arch Biochem Biophys. 1994 Apr;310(1):54-9. doi: 10.1006/abbi.1994.1139.
This study used the rat pancreatoma AR42J cells as model to study hormonal regulation of cholesterol esterase biosynthesis. Our previous studies (Y. Huang and D. Y. Hui, 1991, J. Biol. Chem. 266, 6720-6725) have demonstrated that the AR42J cells responded to cholecystokinin (CCK) and secretin challenge by increasing cholesterol esterase biosynthesis. The current investigation showed that another gastric peptide hormone, bombesin, was also effective in stimulation of cholesterol esterase biosynthesis. Cholesterol esterase biosynthesis in AR42J cells increased 2- to 3-fold in the presence of 5 to 10 nM bombesin or 4 nM CCK. More significantly, when both bombesin and CCK were added to the incubation medium at these concentrations simultaneously, a 15-fold induction of cholesterol esterase biosynthesis was observed. Slot-blot analysis of RNA isolated from control and hormone-stimulated cells revealed no change in the level of cholesterol esterase mRNA, suggesting the post-transcriptional activation of cholesterol esterase biosynthesis. The synergism between bombesin and CCK was not restricted to cholesterol esterase biosynthesis as the simultaneous addition of the two hormones also dramatically increased amylase secretion by AR42J. The results of these studies indicated that gastric peptide hormones may act in concert to stimulate maximally digestive enzyme biosynthesis. The synergistic effects of bombesin and CCK also suggest that distinctive signal transduction pathways may be responsible for the bombesin and CCK induction of pancreatic protein secretion.
本研究以大鼠胰腺瘤AR42J细胞为模型，研究胆固醇酯酶生物合成的激素调节。我们之前的研究（Y. Huang和D. Y. Hui，1991，《生物化学杂志》266，6720 - 6725）表明，AR42J细胞对胆囊收缩素（CCK）和促胰液素刺激有反应，可增加胆固醇酯酶的生物合成。目前的研究表明，另一种胃肽激素蛙皮素也能有效刺激胆固醇酯酶的生物合成。在存在5至10 nM蛙皮素或4 nM CCK的情况下，AR42J细胞中胆固醇酯酶的生物合成增加了2至3倍。更显著的是，当以这些浓度同时将蛙皮素和CCK添加到孵育培养基中时，观察到胆固醇酯酶生物合成有15倍的诱导。对从对照细胞和激素刺激细胞中分离的RNA进行狭缝印迹分析，结果显示胆固醇酯酶mRNA水平没有变化，这表明胆固醇酯酶生物合成存在转录后激活。蛙皮素和CCK之间的协同作用并不局限于胆固醇酯酶的生物合成，因为同时添加这两种激素也显著增加了AR42J细胞淀粉酶的分泌。这些研究结果表明，胃肽激素可能协同作用以最大程度地刺激消化酶的生物合成。蛙皮素和CCK的协同效应还表明，独特的信号转导途径可能负责蛙皮素和CCK诱导的胰腺蛋白分泌。
