Bosch R R, Patel A M, Van Emst-de Vries S E, Smeets R L, De Pont J J, Willems P H
Department of Biochemistry, University of Nijmegen, Netherlands.
Eur J Pharmacol. 1998 Apr 10;346(2-3):345-51. doi: 10.1016/s0014-2999(98)00070-3.
The aminosteroid 1-(6-¿[17beta-3-methoxyestra- 1,3,5(10)-trien- 17-yl]-amino¿hexyl)- 1H-pyrrole-2,5-dione (U73122) and its inactive analogue 1-(6-¿[17beta-3-methoxyestra-1,3,5(10)-trien- 17-yl]-amino¿hexyl-2,5-pyrrolidine-dione (U73343) are widely used to study the involvement of G protein-coupled 1-phosphatidylinositol-phosphodiesterase, or phospholipase C, in receptor-mediated cell activation. The present work shows that both aminosteroids inhibit cholecystokinin-(26-33)-peptide amide (CCK-8)-induced phospholipase D activation equipotently in Chinese hamster ovary cells expressing the cholecystokinin-A receptor (CHO-CCK(A) cells). In addition, the two aminosteroids virtually completely inhibited thapsigargin- and 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced phospholipase D activation. Since the latter two drugs mimic inositol 1,4,5-trisphosphate-mediated Ca2+ mobilisation and 1,2-diacylglycerol-mediated protein kinase C activation. respectively, this suggests that both U73122 and U73343 act downstream of phospholipase C to inhibit receptor-mediated phospholipase D activation. U73122, but not U73343. effectively inhibited both TPA/Ca2+-stimulated phospholipase D activation and TPA/phosphatidylserine-stimulated protein kinase C activation in a homogenate of CHO-CCK(A) cells. The data presented suggest that U73122 may act at the level of protein kinase C to inhibit activation of phospholipase D. The exact site of action of U73343 is presently unknown.
氨基甾体1-(6-[17β-3-甲氧基雌-1,3,5(10)-三烯-17-基]-氨基己基)-1H-吡咯-2,5-二酮(U73122)及其无活性类似物1-(6-[17β-3-甲氧基雌-1,3,5(10)-三烯-17-基]-氨基己基)-2,5-吡咯烷二酮(U73343)被广泛用于研究G蛋白偶联的1-磷脂酰肌醇磷酸二酯酶或磷脂酶C在受体介导的细胞激活中的作用。目前的研究表明，这两种氨基甾体在表达胆囊收缩素-A受体的中国仓鼠卵巢细胞(CHO-CCK(A)细胞)中，对胆囊收缩素-(26-33)-肽酰胺(CCK-8)诱导的磷脂酶D激活具有同等程度的抑制作用。此外，这两种氨基甾体几乎完全抑制了毒胡萝卜素和12-O-十四烷酰佛波醇-13-乙酸酯(TPA)诱导的磷脂酶D激活。由于后两种药物分别模拟了肌醇1,4,5-三磷酸介导的Ca2+动员和1,2-二酰基甘油介导的蛋白激酶C激活，这表明U73122和U73343均在磷脂酶C的下游起作用，以抑制受体介导的磷脂酶D激活。U73122而非U73343能有效抑制CHO-CCK(A)细胞匀浆中TPA/Ca2+刺激的磷脂酶D激活以及TPA/磷脂酰丝氨酸刺激的蛋白激酶C激活。所呈现的数据表明，U73122可能在蛋白激酶C水平发挥作用以抑制磷脂酶D的激活。U73343的确切作用位点目前尚不清楚。
