Identification of superoxide dismutase as a potential urinary marker of carbon tetrachloride-induced hepatic toxicity

• Published in: Food and chemical toxicology 2008-09, Vol.46 (9), p.2972-2983
• Main Authors: Smyth, R., Turton, J.A., Clarke, C.J., York, M.J., Dare, T.O., Lane, C.S., Munday, M.R.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Biological and medical sciences; Biomarkers - urine; Blotting, Western; Carbon tetrachloride; Carbon Tetrachloride Poisoning - pathology; Carbon Tetrachloride Poisoning - urine; Chemical and Drug Induced Liver Injury - pathology; Chemical and Drug Induced Liver Injury - urine; Chemical and industrial products toxicology. Toxic occupational diseases; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Female; Kidney - pathology; Liver; Liver - pathology; Liver Function Tests; Medical sciences; Molecular Sequence Data; Organ Size; Proteinuria - urine; Rat; Rats; Rats, Wistar; Superoxide dismutase; Superoxide Dismutase - urine; Tandem Mass Spectrometry; Toxicity; Toxicology; Urine; Various organic compounds
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/j.fct.2008.05.041

The aim of this study was the identification of a novel protein marker of hepatotoxicity in rat urine. Rats were dosed by gavage with carbon tetrachloride (CCl 4) to induce acute liver injury. Surface enhanced laser desorption/ionisation (SELDI) ProteinChip technology revealed the appearance of a 15.7 kDa protein in the CCl 4-treated rat urine. One-dimensional sodium dodecyl sulphate polyacrylamide electrophoresis (SDS–PAGE) identified an 18.4 kDa protein in the CCl 4-treated rat urine. The appearance of either protein was coincident over a time course during which they first appeared at 12 h post-dosing, peaked at 36 h and had disappeared again within 3 days post-dosing. The protein was identified by in-gel digestion and nano-electrospray (nano-ES)-tandem mass spectrometry as Cu/Zn superoxide dismutase (SOD-1). SOD activity was found to be increased by 61.4-fold in CCl 4-treated rat urine. Western blots of tissue homogenates from the rats revealed a time-dependent loss of SOD-1 from the livers of CCl 4-treated rats matching the time course of SOD-1 appearance in urine. SOD-1 is not specifically located in liver; however, its appearance in urine in response to acute CCl 4-induced hepatotoxicity is a novel finding; this coupled with loss from the liver following injury suggests urinary SOD-1 may be a potential marker of hepatotoxicity.