title: Troglitazone-induced hepatic mitochondrial proteome expression dynamics in heterozygous Sod2(+/-) mice: two-stage oxidative injury.
abstract: The determinants of susceptibility to troglitazone-induced idiosyncratic liver injury have not yet been determined; however, troglitazone has been shown to target mitochondria and induce mitochondria-mediated hepatocellular injury in vitro. The aim of this study was to use a systems approach to analyze the dynamics of mitochondrial changes at the proteome level and more clearly define the mechanisms and time course of troglitazone hepatotoxicity by using a previously characterized mouse model that is highly sensitized to troglitazone hepatotoxicity. Mice heterozygous in mitochondrial superoxide dismutase-2 (Sod2(+/-)) were injected intraperitoneally with troglitazone (30 mg/kg/day) or vehicle daily for 2 or 4 weeks. Hepatic mitochondria were isolated, purified, and subjected to two-dimensional difference gel electrophoresis (2D-DIGE). We found that among the ~1500 resolved hepatic mitochondrial proteins, 70 exhibited significantly altered abundance after troglitazone treatment. MALDI-TOF/TOF MS/MS analysis revealed that early changes (2 weeks) included increased levels of heat shock protein family members (mortalin, HSP7C), Lon protease, and catalase, indicating induction of a mitochondrial stress response. In contrast, after 4 weeks, a number of critical proteins including ATP synthase beta-subunit, aconitase-2, and catalase exhibited decreased abundance, and total protein carbonyls were significantly increased, suggesting uncompensated oxidative damage. Aconitase-2 (ACO2) was decreased at both time points, making this protein a potential sensitive and early biomarker for mitochondrial oxidant stress. These results show that, in this murine model of underlying clinically silent mitochondrial stress, superimposed troglitazone induces a two-stage response: an initial adaptive response, followed by a toxic response involving oxidant injury to mitochondrial proteins.
authors.affiliation: Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597.
authors.forename: Yie Hou
authors.initials: YH
authors.lastname: Lee
authors.forename: Maxey C M
authors.initials: MC
authors.lastname: Chung
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Lin
authors.forename: Urs A
authors.initials: UA
authors.lastname: Boelsterli
mesh_terms: D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002839:Chromans / Q000494:pharmacology*; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000473:pathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D050050:Protein Carbonylation; D020543:Proteome / Q000187:drug effects*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013482:Superoxide Dismutase / Q000235:genetics*; D045162:Thiazolidinediones / Q000494:pharmacology*; D000077288:Troglitazone; D000099156:Superoxide Dismutase 2
chemical_list: D000410:Alanine Transaminase; D002839:Chromans; D007004:Hypoglycemic Agents; D020543:Proteome; D013482:Superoxide Dismutase; D045162:Thiazolidinediones; D000077288:Troglitazone; D000099156:Superoxide Dismutase 2