title: Prolonged oxidative stress impairs insulin-induced GLUT4 translocation in 3T3-L1 adipocytes.
abstract: Prolonged exposure of 3T3-L1 adipocytes to micromolar concentrations of H2O2 results in an impaired response to the acute metabolic effects of insulin. In this study, we further characterized the mechanisms by which oxidative stress impairs insulin stimulation of glucose transport activity. Although insulin induced a 2.5-fold increase in plasma membrane GLUT4 content and a 50% reduction in its abundance in the low-density microsomal (LDM) fraction in control cells, oxidation completely prevented these responses. The net effect of insulin on 2-deoxyglucose uptake activity was reduced in oxidized cells and could be attributed to GLUT1 translocation. Insulin stimulation of insulin receptor substrate (IRS) 1 tyrosine phosphorylation and the association of IRS-1 with phosphatidylinositol (PI) 3-kinase were not impaired by oxidative stress. However, a 1.9-fold increase in the LDM content of the p85 subunit of PI 3-kinase after insulin stimulation was observed in control, but not in oxidized, cells. Moreover, although insulin induced an increase in IRS-1-associated PI 3-kinase activity in the LDM in control cells, this effect was prevented by oxidation. These findings suggest that prolonged low-grade oxidative stress impairs insulin-stimulated GLUT4 translocation, potentially by interfering with compartment-specific activation of PI 3-kinase.
authors.affiliation: Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Rudich
authors.forename: A
authors.initials: A
authors.lastname: Tirosh
authors.forename: R
authors.initials: R
authors.lastname: Potashnik
authors.forename: R
authors.initials: R
authors.lastname: Hemi
authors.forename: H
authors.initials: H
authors.lastname: Kanety
authors.forename: N
authors.initials: N
authors.lastname: Bashan
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003847:Deoxyglucose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D051379:Mice; D008861:Microsomes / Q000201:enzymology; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D009994:Osmolar Concentration; D018384:Oxidative Stress; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation
chemical_list: D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D010750:Phosphoproteins; C495678:Slc2a1 protein, mouse; C495693:Slc2a4 protein, mouse; D003847:Deoxyglucose; D006861:Hydrogen Peroxide; D019869:Phosphatidylinositol 3-Kinases; D005947:Glucose