title: Contribution of liver mitochondrial membrane-bound glutathione transferase to mitochondrial permeability transition pores.
abstract: We recently reported that the glutathione transferase in rat liver mitochondrial membranes (mtMGST1) is activated by S-glutathionylation and the activated mtMGST1 contributes to the mitochondrial permeability transition (MPT) pore and cytochrome c release from mitochondria [Lee, K.K., Shimoji, M., Quazi, S.H., Sunakawa, H., Aniya, Y., 2008. Novel function of glutathione transferase in rat liver mitochondrial membrane: role for cytochrome c release from mitochondria. Toxcol. Appl. Pharmacol. 232, 109-118]. In the present study we investigated the effect of reactive oxygen species (ROS), generator gallic acid (GA) and GST inhibitors on mtMGST1 and the MPT. When rat liver mitochondria were incubated with GA, mtMGST1 activity was increased to about 3 fold and the increase was inhibited with antioxidant enzymes and singlet oxygen quenchers including 1,4-diazabicyclo [2,2,2] octane (DABCO). GA-mediated mtMGST1 activation was prevented by GST inhibitors such as tannic acid, hematin, and cibacron blue and also by cyclosporin A (CsA). In addition, GA induced the mitochondrial swelling which was also inhibited by GST inhibitors, but not by MPT inhibitors CsA, ADP, and bongkrekic acid. GA also released cytochrome c from the mitochondria which was inhibited completely by DABCO, moderately by GST inhibitors, and somewhat by CsA. Ca(2+)-mediated mitochondrial swelling and cytochrome c release were inhibited by MPT inhibitors but not by GST inhibitors. When the outer mitochondrial membrane was isolated after treatment of mitochondria with GA, mtMGST1 activity was markedly increased and oligomer/aggregate of mtMGST1 was observed. These results indicate that mtMGST1 in the outer mitochondrial membrane is activated by GA through thiol oxidation leading to protein oligomerization/aggregation, which may contribute to the formation of ROS-mediated, CsA-insensitive MPT pore, suggesting a novel mechanism for regulation of the MPT by mtMGST1.
authors.affiliation: Laboratory of Molecular Genetics and Pharmacology, School of Health Sciences, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan.
authors.forename: Quazi Sohel
authors.initials: QS
authors.lastname: Hossain
authors.forename: Enkhbaatar
authors.initials: E
authors.lastname: Ulziikhishig
authors.forename: Kang Kwang
authors.initials: KK
authors.lastname: Lee
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Yoko
authors.initials: Y
authors.lastname: Aniya
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005707:Gallic Acid / Q000494:pharmacology; D005982:Glutathione Transferase / Q000378:metabolism*; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D010539:Permeability; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000975:Antioxidants; D005707:Gallic Acid; D045304:Cytochromes c; C122107:microsomal glutathione S-transferase-I; D005982:Glutathione Transferase; D002118:Calcium