Mechanism of action of the antifibrogenic compound gliotoxin in rat liver cells

James G Orr, Val Leel, Gary A Cameron, Carylyn J Marek, Emma L Haughton, Lucy J Elrick, Julie E Trim, Gabrielle M Hawksworth, Andrew P Halestrap, Matthew C Wright

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Abstract

Gliotoxin has been shown to promote a reversal of liver fibrosis in an animal model of the disease although its mechanism of action in the liver is poorly defined. The effects of gliotoxin on activated hepatic stellate cells (HSCs) and hepatocytes have therefore been examined. Addition of gliotoxin (1.5 microM) to culture-activated HSCs resulted in its rapid accumulation, resulting in increased levels of glutathione and apoptosis without any evidence of oxidative stress. In contrast, although hepatocytes also rapidly sequestered gliotoxin, cell death only occurred at high (50-microM) concentrations of gliotoxin and by necrosis. At high concentrations, gliotoxin was metabolized by hepatocytes to a reduced (dithiol) metabolite and glutathione was rapidly oxidized. Fluorescent dye loading experiments showed that gliotoxin caused oxidative stress in hepatocytes. Antioxidants--but not thiol redox active compounds--inhibited both oxidative stress and necrosis in hepatocytes. In contrast, HSC apoptosis was not affected by antioxidants but was potently abrogated by thiol redox active compounds. The adenine nucleotide transporter (ANT) is implicated in mitochondrial-dependent apoptosis. HSCs expressed predominantly nonliver ANT isoform 1, and gliotoxin treatment resulted in a thiol redox-dependent alteration in ANT mobility in HSC extracts, but not hepatocyte extracts. In conclusion, these data suggest that gliotoxin stimulates the apoptosis of HSCs through a specific thiol redox-dependent interaction with the ANT. Further understanding of this mechanism of cell death will aid in finding therapeutics that specifically stimulate HSC apoptosis in the liver, a promising approach to antifibrotic therapy.

Original languageEnglish
Pages (from-to)232-242
Number of pages11
JournalHepatology
Volume40
Issue number1
DOIs
Publication statusPublished - Jul 2004

Keywords

  • Animals
  • Antioxidants
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Gliotoxin
  • Glutathione
  • Hepatocytes
  • Liver
  • Liver Cirrhosis
  • Male
  • Necrosis
  • Rats
  • Rats, Sprague-Dawley
  • Reactive Oxygen Species
  • Reducing Agents
  • Sulfhydryl Compounds
  • mitochondrial permeability transition
  • NF-kappa-B
  • hepatic stellate cells
  • adenine-nucleotide translocase
  • fungal toxin
  • gliotoxin
  • mediated apoptosis
  • fibrosis
  • hepatocytes
  • inhibition
  • expression

Cite this

Orr, J. G., Leel, V., Cameron, G. A., Marek, C. J., Haughton, E. L., Elrick, L. J., ... Wright, M. C. (2004). Mechanism of action of the antifibrogenic compound gliotoxin in rat liver cells. Hepatology, 40(1), 232-242. https://doi.org/10.1002/hep.20254

Mechanism of action of the antifibrogenic compound gliotoxin in rat liver cells. / Orr, James G; Leel, Val; Cameron, Gary A; Marek, Carylyn J; Haughton, Emma L; Elrick, Lucy J; Trim, Julie E; Hawksworth, Gabrielle M; Halestrap, Andrew P; Wright, Matthew C.

In: Hepatology, Vol. 40, No. 1, 07.2004, p. 232-242.

Research output: Contribution to journalArticle

Orr, JG, Leel, V, Cameron, GA, Marek, CJ, Haughton, EL, Elrick, LJ, Trim, JE, Hawksworth, GM, Halestrap, AP & Wright, MC 2004, 'Mechanism of action of the antifibrogenic compound gliotoxin in rat liver cells', Hepatology, vol. 40, no. 1, pp. 232-242. https://doi.org/10.1002/hep.20254
Orr JG, Leel V, Cameron GA, Marek CJ, Haughton EL, Elrick LJ et al. Mechanism of action of the antifibrogenic compound gliotoxin in rat liver cells. Hepatology. 2004 Jul;40(1):232-242. https://doi.org/10.1002/hep.20254
Orr, James G ; Leel, Val ; Cameron, Gary A ; Marek, Carylyn J ; Haughton, Emma L ; Elrick, Lucy J ; Trim, Julie E ; Hawksworth, Gabrielle M ; Halestrap, Andrew P ; Wright, Matthew C. / Mechanism of action of the antifibrogenic compound gliotoxin in rat liver cells. In: Hepatology. 2004 ; Vol. 40, No. 1. pp. 232-242.
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abstract = "Gliotoxin has been shown to promote a reversal of liver fibrosis in an animal model of the disease although its mechanism of action in the liver is poorly defined. The effects of gliotoxin on activated hepatic stellate cells (HSCs) and hepatocytes have therefore been examined. Addition of gliotoxin (1.5 microM) to culture-activated HSCs resulted in its rapid accumulation, resulting in increased levels of glutathione and apoptosis without any evidence of oxidative stress. In contrast, although hepatocytes also rapidly sequestered gliotoxin, cell death only occurred at high (50-microM) concentrations of gliotoxin and by necrosis. At high concentrations, gliotoxin was metabolized by hepatocytes to a reduced (dithiol) metabolite and glutathione was rapidly oxidized. Fluorescent dye loading experiments showed that gliotoxin caused oxidative stress in hepatocytes. Antioxidants--but not thiol redox active compounds--inhibited both oxidative stress and necrosis in hepatocytes. In contrast, HSC apoptosis was not affected by antioxidants but was potently abrogated by thiol redox active compounds. The adenine nucleotide transporter (ANT) is implicated in mitochondrial-dependent apoptosis. HSCs expressed predominantly nonliver ANT isoform 1, and gliotoxin treatment resulted in a thiol redox-dependent alteration in ANT mobility in HSC extracts, but not hepatocyte extracts. In conclusion, these data suggest that gliotoxin stimulates the apoptosis of HSCs through a specific thiol redox-dependent interaction with the ANT. Further understanding of this mechanism of cell death will aid in finding therapeutics that specifically stimulate HSC apoptosis in the liver, a promising approach to antifibrotic therapy.",
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T1 - Mechanism of action of the antifibrogenic compound gliotoxin in rat liver cells

AU - Orr, James G

AU - Leel, Val

AU - Cameron, Gary A

AU - Marek, Carylyn J

AU - Haughton, Emma L

AU - Elrick, Lucy J

AU - Trim, Julie E

AU - Hawksworth, Gabrielle M

AU - Halestrap, Andrew P

AU - Wright, Matthew C

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N2 - Gliotoxin has been shown to promote a reversal of liver fibrosis in an animal model of the disease although its mechanism of action in the liver is poorly defined. The effects of gliotoxin on activated hepatic stellate cells (HSCs) and hepatocytes have therefore been examined. Addition of gliotoxin (1.5 microM) to culture-activated HSCs resulted in its rapid accumulation, resulting in increased levels of glutathione and apoptosis without any evidence of oxidative stress. In contrast, although hepatocytes also rapidly sequestered gliotoxin, cell death only occurred at high (50-microM) concentrations of gliotoxin and by necrosis. At high concentrations, gliotoxin was metabolized by hepatocytes to a reduced (dithiol) metabolite and glutathione was rapidly oxidized. Fluorescent dye loading experiments showed that gliotoxin caused oxidative stress in hepatocytes. Antioxidants--but not thiol redox active compounds--inhibited both oxidative stress and necrosis in hepatocytes. In contrast, HSC apoptosis was not affected by antioxidants but was potently abrogated by thiol redox active compounds. The adenine nucleotide transporter (ANT) is implicated in mitochondrial-dependent apoptosis. HSCs expressed predominantly nonliver ANT isoform 1, and gliotoxin treatment resulted in a thiol redox-dependent alteration in ANT mobility in HSC extracts, but not hepatocyte extracts. In conclusion, these data suggest that gliotoxin stimulates the apoptosis of HSCs through a specific thiol redox-dependent interaction with the ANT. Further understanding of this mechanism of cell death will aid in finding therapeutics that specifically stimulate HSC apoptosis in the liver, a promising approach to antifibrotic therapy.

AB - Gliotoxin has been shown to promote a reversal of liver fibrosis in an animal model of the disease although its mechanism of action in the liver is poorly defined. The effects of gliotoxin on activated hepatic stellate cells (HSCs) and hepatocytes have therefore been examined. Addition of gliotoxin (1.5 microM) to culture-activated HSCs resulted in its rapid accumulation, resulting in increased levels of glutathione and apoptosis without any evidence of oxidative stress. In contrast, although hepatocytes also rapidly sequestered gliotoxin, cell death only occurred at high (50-microM) concentrations of gliotoxin and by necrosis. At high concentrations, gliotoxin was metabolized by hepatocytes to a reduced (dithiol) metabolite and glutathione was rapidly oxidized. Fluorescent dye loading experiments showed that gliotoxin caused oxidative stress in hepatocytes. Antioxidants--but not thiol redox active compounds--inhibited both oxidative stress and necrosis in hepatocytes. In contrast, HSC apoptosis was not affected by antioxidants but was potently abrogated by thiol redox active compounds. The adenine nucleotide transporter (ANT) is implicated in mitochondrial-dependent apoptosis. HSCs expressed predominantly nonliver ANT isoform 1, and gliotoxin treatment resulted in a thiol redox-dependent alteration in ANT mobility in HSC extracts, but not hepatocyte extracts. In conclusion, these data suggest that gliotoxin stimulates the apoptosis of HSCs through a specific thiol redox-dependent interaction with the ANT. Further understanding of this mechanism of cell death will aid in finding therapeutics that specifically stimulate HSC apoptosis in the liver, a promising approach to antifibrotic therapy.

KW - Animals

KW - Antioxidants

KW - Cells, Cultured

KW - Dose-Response Relationship, Drug

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KW - Hepatocytes

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KW - Male

KW - Necrosis

KW - Rats

KW - Rats, Sprague-Dawley

KW - Reactive Oxygen Species

KW - Reducing Agents

KW - Sulfhydryl Compounds

KW - mitochondrial permeability transition

KW - NF-kappa-B

KW - hepatic stellate cells

KW - adenine-nucleotide translocase

KW - fungal toxin

KW - gliotoxin

KW - mediated apoptosis

KW - fibrosis

KW - hepatocytes

KW - inhibition

KW - expression

U2 - 10.1002/hep.20254

DO - 10.1002/hep.20254

M3 - Article

C2 - 15239107

VL - 40

SP - 232

EP - 242

JO - Hepatology

JF - Hepatology

SN - 0270-9139

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ER -