Pharmaceutical Sciences Faculty Publications

Oxidative Inactivation of Key Mitochondrial Proteins Leads to Dysfunction and Injury in Hepatic Ischemia Reperfusion

Document Type

Article

Publication Date

10-1-2008

Journal Title

Gastroenterology

ISSN

1528-0012

Volume

135

Issue

4

First Page

1344

Last Page

1357

DOI

10.1053/j.gastro.2008.06.048

PubMed ID

18778711

PubMed Central® ID

PMC2597302

Abstract

BACKGROUND & AIMS: Ischemia-reperfusion (I/R) is a major mechanism of liver injury following hepatic surgery or transplantation. Despite numerous reports on the role of oxidative/nitrosative stress and mitochondrial dysfunction in hepatic I/R injury, the proteins that are oxidatively modified during I/R damage are poorly characterized. This study was aimed at investigating the oxidatively modified proteins underlying the mechanism for mitochondrial dysfunction in hepatic I/R injury. We also studied the effects of a superoxide dismutase mimetic/peroxynitrite scavenger metalloporphyrin (MnTMPyP) on oxidatively modified proteins and their functions.

METHODS: The oxidized and/or S-nitrosylated mitochondrial proteins from I/R-injured mouse livers with or without MnTMPyP pretreatment were labeled with biotin-N-maleimide, purified with streptavidin-agarose, and resolved by 2-dimensional gel electrophoresis. The identities of the oxidatively modified proteins were determined using mass spectrometric analysis. Liver histopathology, serum transaminase levels, nitrosative stress markers, and activities of oxidatively modified mitochondrial proteins were measured.

RESULTS: Comparative 2-dimensional gel analysis revealed markedly increased numbers of oxidized and S-nitrosylated mitochondrial proteins following hepatic I/R injury. Many key mitochondrial enzymes involved in cellular defense, fat metabolism, energy supply, and chaperones were identified as being oxidatively modified proteins. Pretreatment with MnTMPyP attenuated the I/R-induced increased serum transaminase levels, histologic damage, increased inducible nitric oxide synthase expression, and S-nitrosylation and/or nitration of various key mitochondrial proteins. MnTMPyP pretreatment also restored I/R-induced suppressed activities of mitochondrial aldehyde dehydrogenase, 3-ketoacyl-CoA thiolases, and adenosine triphosphate synthase.

CONCLUSIONS: These results suggest that increased nitrosative stress is critically important in promoting S-nitrosylation and nitration of various mitochondrial proteins, leading to mitochondrial dysfunction with decreased energy supply and increased hepatic injury.

Keywords

Energy metabolism, enzymes, liver, metalloporphyrins, mitochondrial proteins, nitrites, nitrogen, oxidation-reduction, oxidative stress, reperfusion injury, sequence analysis, protein, superoxide dismutase, tandem mass spectrometry, tyrosine

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