A Selective, Potent Inhibitor of PI 3-Kinase
I 3 Kinase is an enzyme implicated in growth factor signal transduction by associating with receptor and non-receptory tyrosine kinases. Wortmannin, a fungal metabolite (Penicillium fumiculosum), is a potent and specific inhibitor of phosphatidylinositol 3-kinase (PI-3K). It is highly cell-permeable, binds to the catalytic subunit of PI-3K and inhibits the enzyme activity in vitro and in vivo.
In purified preparations and cell-free cytosolic fractions it is active at 5 nM. In fibroblasts Wortmannin abolishes PDGF-mediated Inositol(3,4,5) P3�formation (IC50 = 5 nM). In guinea pig neutrophils it inhibits fMLP induced PIP3 and superoxide anion production (IC50 =50 nM), and also phospholipase D activation. In PC12 cells treated with NGF, Wortmannin blocks the elongation of neurites. In rat basophilic leukemia (RBL-2H3) cells it inhibits IgE mediated histamine secretion. At higher concentrations Wortmanin inhibits other kinases such as myosin light chain kinase (IC50 = 200 nM) and MAP kinase activation (IC50 = 200 - 300 nM) induced by platelet activating factor.
Protein Kinase Inhibitors and Activators; PI 3-Kinase Inhibitors.