title: Protein expression profiling of glutathione S-transferase pi null mice as a strategy to identify potential markers of resistance to paracetamol-induced toxicity in the liver.
abstract: GST pi (GSTP) is a member of the glutathione S-transferase (EC 2.5.1.18; GST) family of enzymes that catalyse the conjugation of electrophilic species with reduced glutathione and thus play an important role in the detoxification of electrophilic metabolites. Deletion of GSTP in mice has previously been shown to lead to enhanced susceptibility to chemical-induced skin carcinoma, consistent with its known metabolic functions. A decreased susceptibility to paracetamol hepatotoxicity has also been observed, which has not been fully explained. One possibility is that deletion of the GSTP gene locus results in compensatory changes in other proteins involved in defence against chemical stress. We have therefore used complementary protein expression profiling techniques to perform a systematic comparison of the protein expression profiles of livers from GSTP null and wild-type mice. Analysis of liver proteins by two-dimensional electrophoresis confirmed the absence of GSTP in null mice whereas GSTP represented 3-5% of soluble protein in livers from wild-type animals. There was a high degree of quantitative and qualitative similarity in other liver proteins between GSTP null and wild-type mice. There was no evidence that the absence of GSTP in null animals resulted in enhanced expression of other GST isoforms in the null mice (GST alpha, 1.48%, GST mu, 1.68% of resolved proteins) compared with the wild-type animals (GST alpha, 1.50%, GST mu, 1.40%). In contrast, some members of the thiol specific antioxidant family of proteins, notably antioxidant protein 2 and thioredoxin peroxidases, were expressed at a higher level in the GSTP null mouse livers. These changes presumably reflect the recently described role of GSTP in cell signalling and may underlie the protection against paracetamol toxicity seen in these animals.
authors.affiliation: Department of Pharmacology and Therapeutics, University of Liverpool, Merseyside, UK. neilk@liv.ac.uk
authors.forename: Neil R
authors.initials: NR
authors.lastname: Kitteringham
authors.forename: Helen
authors.initials: H
authors.lastname: Powell
authors.forename: Rosalind E
authors.initials: RE
authors.lastname: Jenkins
authors.forename: Jane
authors.initials: J
authors.lastname: Hamlett
authors.forename: Cerys
authors.initials: C
authors.lastname: Lovatt
authors.forename: Robert
authors.initials: R
authors.lastname: Elsby
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Henderson
authors.forename: C Roland
authors.initials: CR
authors.lastname: Wolf
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Pennington
authors.forename: B Kevin
authors.initials: BK
authors.lastname: Park
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D005982:Glutathione Transferase / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D010544:Peroxidases; D054465:Peroxiredoxin VI; D054464:Peroxiredoxins; D011110:Polymorphism, Genetic; D040081:Protein Array Analysis; D020033:Protein Isoforms; D011506:Proteins / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
chemical_list: D000975:Antioxidants; D010455:Peptides; D020033:Protein Isoforms; D011506:Proteins; D010544:Peroxidases; D054465:Peroxiredoxin VI; D054464:Peroxiredoxins; C515983:Prdx6 protein, mouse; D005982:Glutathione Transferase