Okada T, Sakuma L, Fukui Y, Hazeki O, Ui M
Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
J Biol Chem. 1994 Feb 4;269(5):3563-7.
Wortmannin, a fungal metabolite, inhibited 32P labeling of phosphatidylinositol trisphosphate, a product of phosphatidylinositol 3-kinase (PI 3-kinase), selectively in formyl peptide-stimulated 32P-loaded guinea pig neutrophils. The inhibition was of the same concentration dependence (with the half-maximal inhibition around 50 nM) as was observed for the simultaneous inhibition of formyl peptide-induced superoxide anion production. Wortmannin inhibited all three of the PI 3-kinase activities found in the cytosol fraction of guinea pig neutrophils, with a similar dose dependence (the half-maximal effects at 5 nM). Wortmannin was also effective on an immunologically purified preparation of the enzyme. The inhibition was of a noncompetitive type with regard to ATP and was observed consistently when PI, PI monophosphate, or PI bisphosphate was used as substrate. PI 4-kinase activity was not affected. It is concluded, therefore, that wortmannin abolished the formyl peptide-induced stimulation of neutrophils as a result of the inhibition of PI 3-kinase. An essential role of PI 3-kinase in receptor-mediated signaling in neutrophils thus evidenced with the use of wortmannin will be expanded to other cellular signaling systems.
渥曼青霉素是一种真菌代谢产物，在甲酰化肽刺激的32P标记豚鼠中性粒细胞中，它能选择性抑制磷脂酰肌醇三磷酸（磷脂酰肌醇3激酶（PI 3激酶）的产物）的32P标记。这种抑制作用与同时抑制甲酰化肽诱导的超氧阴离子产生所观察到的浓度依赖性相同（半数最大抑制浓度约为50 nM）。渥曼青霉素抑制了豚鼠中性粒细胞胞质部分中发现的所有三种PI 3激酶活性，且具有相似的剂量依赖性（5 nM时产生半数最大效应）。渥曼青霉素对免疫纯化的该酶制剂也有效。就ATP而言，这种抑制属于非竞争性类型，并且当使用磷脂酰肌醇（PI）、一磷酸磷脂酰肌醇或二磷酸磷脂酰肌醇作为底物时，始终能观察到这种抑制作用。PI 4激酶活性不受影响。因此可以得出结论，渥曼青霉素通过抑制PI 3激酶消除了甲酰化肽对中性粒细胞的刺激。利用渥曼青霉素证明的PI 3激酶在中性粒细胞受体介导信号传导中的重要作用将扩展到其他细胞信号系统。
