Fujimoto M, Sakata T, Tsuruta Y, Iwagami S, Teraoka H, Mihara S, Fukiishi Y, Ide M
Shionogi Research Laboratories, Shionogi & Co., Ltd., Osaka, Japan.
Biochem Pharmacol. 1990 Dec 15;40(12):2661-70. doi: 10.1016/0006-2952(90)90584-8.
Bradykinin-stimulated prostacyclin synthesis in porcine aortic endothelial cells was enhanced by pretreatment of the cells with pertussis toxin or islet-activating protein (IAP) for 5 hr or longer. Although ADP-ribosylation of a protein with a molecular weight of 41-42 kD in the cell membranes was completed by 3 hr after the addition of IAP into the incubation medium, there was good correlation between enhancement of bradykinin-induced prostacyclin synthesis and ADP-ribosylation of the IAP substrate over a wide range of IAP concentrations. Furthermore, even if IAP was removed from the incubation medium at 3 hr, bradykinin-induced prostaglandin synthesis at 24 hr was still potentiated. Cycloheximide and actinomycin D enhanced bradykinin-induced prostacyclin synthesis and apparently blocked the effect of IAP. Since this result suggested the involvement of an inhibitor protein(s) of prostacyclin synthesis in the IAP effect, we studied the effect of IAP on the level of lipocortin I which is known to inhibit phospholipase A2. Western and Northern blot analyses revealed that IAP decreased the amounts of protein and mRNA of lipocortin I. These results suggest that the enhancement of bradykinin-induced prostacyclin synthesis by IAP is associated with a decrease in the level of lipocortin I.
用百日咳毒素或胰岛激活蛋白（IAP）预处理猪主动脉内皮细胞5小时或更长时间，可增强缓激肽刺激的前列环素合成。虽然在孵育培养基中加入IAP后3小时，细胞膜中分子量为41 - 42kD的蛋白质的ADP核糖基化就已完成，但在很宽的IAP浓度范围内，缓激肽诱导的前列环素合成增强与IAP底物的ADP核糖基化之间存在良好的相关性。此外，即使在3小时时从孵育培养基中去除IAP，24小时时缓激肽诱导的前列腺素合成仍会增强。放线菌酮和放线菌素D增强了缓激肽诱导的前列环素合成，并明显阻断了IAP的作用。由于这一结果提示IAP的作用涉及前列环素合成的一种抑制蛋白，我们研究了IAP对已知可抑制磷脂酶A2的脂皮质素I水平的影响。蛋白质印迹和Northern印迹分析显示，IAP降低了脂皮质素I的蛋白质和mRNA含量。这些结果提示，IAP增强缓激肽诱导的前列环素合成与脂皮质素I水平降低有关。
