Insulin cannot activate extracellular-signal-related kinase due to inability to generate reactive oxygen species in SK-N-BE(2) human neuroblastoma cells.
The insulin-mediated Ras/mitogen-activated protein (MAP) kinase cascade was examined in SK-N-BE(2) and PC12 cells, which can and cannot produce reactive oxygen species (ROS), respectively. Tyrosine phosphorylation of the insulin receptor and insulin receptor substrate 1 (IRS-1) was much lower in SK-N-BE(2) cells than in PC12 cells when the cells were treated with insulin. The insulin-mediated interaction of IRS-1 with Grb2 was observed in PC12 but not in SK-N-BE(2) cells. Moreover, the activity of extracellular-signal-related kinase (ERK) was much lower in SK-N-BE(2) than in PC12 cells when the cells were treated with insulin. Application of exogenous H2O2 caused increased tyrosine phosphorylation and Grb2 binding to IRS-1 in SK-N-BE(2) cells, while exposure to an H2O2 scavenger (N-acetylcysteine) or to a phophatidylinositol-3 kinase inhibitor (wortmannin), and expression of a dominant negative Rac1, decreased the activation of ERK in insulin-stimulated PC12 cells. These results indicate that the transient increase of ROS is needed to activate ERK in insulin-mediated signaling and that an inability to generate ROS is the reason for the insulin insensitivity of SK-N-BE(2) cells.
Hwang
Jung-Jin
JJ
Department of Biology, Ewha Womans University, Seoul 120-750, Korea.
Hur
Kyu Chung
KC
D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009447:Neuroblastoma / Q000201:enzymology / Q000378:metabolism*; D016716:PC12 Cells; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism
C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; D048049:Extracellular Signal-Regulated MAP Kinases; D018631:ras Proteins