title: Oxidative stress mediates apoptotic changes induced by hyperglycemia in human tubular kidney cells.
abstract: Reactive oxygen species (ROS) are important mediators for several biologic responses, including apoptosis. The present study evaluated the time course of changes in intracellular ROS production and apoptosis-related proteins, as well as apoptotic changes in human tubular proximal cells (HK-2 cells) exposed to hyperglycemia. Apoptosis (annexin V binding), ROS formation (fluorescence probe dichlorofluorescin diacetate and FACScan flow cytometry), and X chromosome-linked protein (XIAP; Western blot) were studied in HK-2 cells grown in a medium containing normal (NG) or high glucose (HG) concentrations (5.5 or 30 mM, respectively) for 18 to 48 h. HG promoted an increase (65% at 18 h and 73% at 24 h; P < 0.05 versus NG) in intracellular ROS generation. At 18 h, the NF-kB binding activity (evaluated by electrophoretic mobility-shift assay) was suppressed by HG. At the same time, the expression of NF-kB-induced antiapoptotic XIAP was reduced in HG-treated cells. Apoptotic changes were observed at 48 h (34 +/- 7% in HG versus 10 +/- 3% in NG; P < 0.001). Changes in ROS production at 24 h predicted changes in the apoptotic index at 48 h (r = 0.96, P < 0.0001). These results suggest that hyperglycemia induces apoptotic changes in human tubular cells via an increase in oxidative stress and that a downregulation of antiapoptotic protein XIAP is a component of this response.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, University of Genoa, Genoa, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Verzola
authors.forename: Maria Bianca
authors.initials: MB
authors.lastname: Bertolotto
authors.forename: Barbara
authors.initials: B
authors.lastname: Villaggio
authors.forename: Luciano
authors.initials: L
authors.lastname: Ottonello
authors.forename: Franco
authors.initials: F
authors.lastname: Dallegri
authors.forename: Francesca
authors.initials: F
authors.lastname: Salvatore
authors.forename: Valeria
authors.initials: V
authors.lastname: Berruti
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Gandolfo
authors.forename: Giacomo
authors.initials: G
authors.lastname: Garibotto
authors.forename: Giacomo
authors.initials: G
authors.lastname: Deferrari
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D002478:Cells, Cultured; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000378:metabolism*; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013997:Time Factors
chemical_list: D017382:Reactive Oxygen Species