title: Gsta4 Null Mouse Embryonic Fibroblasts Exhibit Enhanced Sensitivity to Oxidants: Role of 4-Hydroxynonenal in Oxidant Toxicity.
abstract: The alpha class glutathione s-transferase (GST) isozyme GSTA4-4 (EC2.5.1.18) exhibits high catalytic efficiency to-wards 4-hydroxynon-2-enal (4-HNE), a major end product of oxidative stress induced lipid peroxidation. Exposure of cells and tissues to heat, radiation, and chemicals has been shown to induce oxidative stress resulting in elevated concentrations of 4-HNE that can be detrimental to cell survival. Alternatively, at physiological levels 4-HNE acts as a signaling molecule conveying the occurrence of oxidative events initiating the activation of adaptive pathways. To examine the impact of oxidative/electrophilic stress in a model with impaired 4-HNE metabolizing capability, we disrupted theGsta4 gene that encodes GSTA4-4 in mice. The effect of electrophile and oxidants on embryonic fibroblasts (MEF) isolated from wild type (WT) andGsta4 null mice were examined. Results indicate that in the absence of GSTA4-4, oxidant-induced toxicity is potentiated and correlates with elevated accumulation of 4-HNE adducts and DNA damage. Treatment ofGsta4 null MEF with 1,1,4-tris(acetyloxy)-2(E)-nonene [4-HNE(Ac)3], a pro-drug form of 4-HNE, resulted in the activation and phosphorylation of the c-jun-N-terminal kinase (JNK), extracellular-signal-regulated kinases (ERK 1/2) and p38 mitogen activated protein kinases (p38 MAPK) accompanied by enhanced cleavage of caspase-3. Interestingly, when recombinant mammalian or invertebrate GSTs were delivered toGsta4 null MEF, activation of stress-related kinases in 4-HNE(Ac)3treatedGsta4 null MEF were inversely correlated with the catalytic efficiency of delivered GSTs towards 4-HNE. Our data suggest that GSTA4-4 plays a major role in protecting cells from the toxic effects of oxidant chemicals by attenuating the accumulation of 4-HNE.
authors.affiliation: Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA ; Central Arkansas Veterans Healthcare System, Little Rock, USA.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: McElhanon
authors.affiliation: Central Arkansas Veterans Healthcare System, Little Rock, USA ; Department of Internal Medicine, Nephrology Division, University of Arkansas for Medical Sciences, Little Rock, USA.
authors.forename: Chhanda
authors.initials: C
authors.lastname: Bose
authors.affiliation: Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA ; Central Arkansas Veterans Healthcare System, Little Rock, USA.
authors.forename: Rajendra
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA ; Central Arkansas Veterans Healthcare System, Little Rock, USA.
authors.forename: Liping
authors.initials: L
authors.lastname: Wu
authors.affiliation: Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, USA.
authors.forename: Yogesh C
authors.initials: YC
authors.lastname: Awasthi
authors.affiliation: Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA ; Central Arkansas Veterans Healthcare System, Little Rock, USA.
authors.forename: Sharda P
authors.initials: SP
authors.lastname: Singh
keywords: Glutathione Transferase; Lipid Peroxidation; Oxidants; Protein Adducts; Stress Kinases