title: Extracellular signal-regulated kinase activation mediates mitochondrial dysfunction and necrosis induced by hydrogen peroxide in renal proximal tubular cells.
abstract: Although tubular necrosis in acute renal failure is associated with excessive production of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), the mechanism of ROS-induced cell necrosis remains poorly understood. In this study, we examined the role of the extracellular signaling-regulated kinase (ERK) pathway in H2O2-induced necrosis of renal proximal tubular cells (RPTC) in primary culture. Exposure of 60 to 70% confluent RPTC to 1 mM H2O2 for 3 h resulted in 44% necrotic cell death, as measured by trypan blue uptake, and inactivation of mitogen-activated protein kinase kinase (MEK), the upstream activator of ERK, by either 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene (U0126) or 2-(2'-amino-3'-methoxyphenyl)-oxanaphthalen-4-one (PD98059) or overexpression of dominant-negative mutant of MEK1, inhibited cell death. In contrast, overexpression of active MEK1 enhanced H2O2-induced cell death. H2O2 treatment led to the loss of mitochondrial membrane potential (MMP) in RPTC, which was decreased by U0126 and PD98059. Furthermore, inhibition of the MEK/ERK pathway decreased oxidant-mediated ERK1/2 activation and mitochondrial swelling in isolated renal cortex mitochondria. However, treatment with cyclosporin A (CsA), a mitochondrial permeability transition blocker, did not suppress RPTC necrotic cell death, loss of MMP, and mitochondrial swelling. We suggest that ERK is a critical mediator of mitochondrial dysfunction and necrotic cell death of renal epithelial cells following oxidant injury. Oxidant-induced necrotic cell death was mediated by a CsA-insensitive loss of MMP that is regulated by the ERK pathway.
authors.affiliation: Department of Medicine Rhode Island Hospital, Middle House 301, 593 Eddy Street, Providence, RI 02903, USA. szhuang@lifespan.org
authors.forename: Shougang
authors.initials: S
authors.lastname: Zhuang
authors.forename: Gilbert R
authors.initials: GR
authors.lastname: Kinsey
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Jiahuai
authors.initials: J
authors.lastname: Han
authors.forename: Rick G
authors.initials: RG
authors.lastname: Schnellmann
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D005260:Female; D006861:Hydrogen Peroxide / Q000633:toxicity*; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000473:pathology* / Q000503:physiopathology*; D015227:Lipid Peroxidation / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D008933:Mitochondrial Swelling / Q000187:drug effects; D009336:Necrosis / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology; D016877:Oxidants / Q000633:toxicity*; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011817:Rabbits
chemical_list: D016877:Oxidants; D047428:Protein Kinase Inhibitors; D016572:Cyclosporine; D006861:Hydrogen Peroxide; D048049:Extracellular Signal-Regulated MAP Kinases