title: S-D-Lactoylglutathione can be an alternative supply of mitochondrial glutathione.
abstract: The mitochondrial pool of GSH (glutathione) is considered the major redox system in maintaining matrix redox homeostasis, preserving sulfhydryl groups of mitochondrial proteins in appropriate redox state, in defending mitochondrial DNA integrity and protecting mitochondrial-derived ROS, and in defending mitochondrial membranes against oxidative damage. Despite its importance in maintaining mitochondrial functionality, GSH is synthesized exclusively in the cytoplasm and must be actively transported into mitochondria. In this work we found that SLG (S-D-lactoylglutathione), an intermediate of the glyoxalase system, can enter the mitochondria and there be hydrolyzed from mitochondrial glyoxalase II enzyme to D-lactate and GSH. To demonstrate SLG transport from cytosol to mitochondria we used radiolabeled compounds and the results showed two different kinetic curves for SLG or GSH substrates, indicating different kinetic transport. Also, the incubation of functionally and intact mitochondria with SLG showed increased GSH levels in normal mitochondria and in artificially uncoupled mitochondria, demonstrating transport not linked to ATP presence. As well mitochondrial-swelling assay confirmed SLG entrance into organelles. Moreover we observed oxygen uptake and generation of membrane potential probably linked to D-lactate oxidation which is a product of SLG hydrolysis. The latter data were confirmed by oxidation of D-lactate in mitochondria evaluated by measuring mitochondrial D-lactate dehydrogenize activity. In this work we also showed the presence of mitochondrial glyoxalase II in inter-membrane space and mitochondrial matrix and we investigated the role of SLG in whole cells. In conclusion, this work showed new alternative sources of GSH supply to the mitochondria by SLG, an intermediate of the glyoxalase system.
authors: Department of Clinical Sciences, Section of Biochemistry, Biology, and Physics, Università Politecnica delle Marche, Ancona, Italy. Electronic address: t.armeni@univpm.it.
authors: Tatiana
authors: T
authors: Armeni
authors: Department of Clinical Sciences, Section of Biochemistry, Biology, and Physics, Università Politecnica delle Marche, Ancona, Italy.
authors: Laura
authors: L
authors: Cianfruglia
authors: Department of Clinical Sciences, Section of Biochemistry, Biology, and Physics, Università Politecnica delle Marche, Ancona, Italy.
authors: Francesco
authors: F
authors: Piva
authors: Department of Experimental Medicine and Biochemical Sciences, Università di Perugia, Perugia, Italy.
authors: Lorena
authors: L
authors: Urbanelli
authors: Department of Clinical Sciences, Section of Biochemistry, Biology, and Physics, Università Politecnica delle Marche, Ancona, Italy.
authors: Maria
authors: M
authors: Luisa Caniglia
authors: Department of Molecular and Clinical Sciences, Università Politecnica delle Marche, Ancona, Italy.
authors: Armanda
authors: A
authors: Pugnaloni
authors: Department of Clinical Sciences, Section of Biochemistry, Biology, and Physics, Università Politecnica delle Marche, Ancona, Italy.
authors: Giovanni
authors: G
authors: Principato
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002250:Carbon Radioisotopes; D003600:Cytosol / Q000378:metabolism; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D045022:Lactate Dehydrogenases; D019344:Lactic Acid / Q000096:biosynthesis; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D013869:Thiolester Hydrolases / Q000378:metabolism; D014316:Tritium; D000099301:Hydroxyacylglutathione Hydrolase
chemical_list: D000255:Adenosine Triphosphate; D002250:Carbon Radioisotopes; D005978:Glutathione; D045022:Lactate Dehydrogenases; D019344:Lactic Acid; D013869:Thiolester Hydrolases; D014316:Tritium; D000099301:Hydroxyacylglutathione Hydrolase; C071195:D-lactate dehydrogenase; C013585:S-lactoylglutathione
keywords: Glutathione; Glyoxalase II enzyme; Glyoxalase system; Mitochondria; S-D-Lactoylglutathione; Thiols