Inhibition of hepatocyte autophagy increases tumor necrosis factor-dependent liver injury by promoting caspase-8 activation

M. Amir, E. Zhao, L. Fontana, H. Rosenberg, Kathryn E. Tanaka, G. Gao, M. J. Czaja

Research output: Contribution to journalArticle

86 Citations (Scopus)

Abstract

Recent investigations have demonstrated a complex interrelationship between autophagy and cell death. A common mechanism of cell death in liver injury is tumor necrosis factor (TNF) cytotoxicity. To better delineate the in vivo function of autophagy in cell death, we examined the role of autophagy in TNF-induced hepatic injury. Atg7Δhep mice with a hepatocyte-specific knockout of the autophagy gene atg7 were generated and cotreated with D-galactosamine (GalN) and lipopolysaccharide (LPS). GalN/LPS-treated Atg7Δhep mice had increased serum alanine aminotransferase levels, histological injury, numbers of TUNEL (terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate nick end-labeling)-positive cells and mortality as compared with littermate controls. Loss of hepatocyte autophagy similarly sensitized to GalN/TNF liver injury. GalN/LPS injury in knockout animals did not result from altered production of TNF or other cytokines. Atg7Δhep mice had accelerated activation of the mitochondrial death pathway and caspase-3 and -7 cleavage. Increased cell death did not occur from direct mitochondrial toxicity or a lack of mitophagy, but rather from increased activation of initiator caspase-8 causing Bid cleavage. GalN blocked LPS induction of hepatic autophagy, and increased autophagy from beclin 1 overexpression prevented GalN/LPS injury. Autophagy, therefore, mediates cellular resistance to TNF toxicity in vivo by blocking activation of caspase-8 and the mitochondrial death pathway, suggesting that autophagy is a therapeutic target in TNF-dependent tissue injury.

Original languageEnglish (US)
Pages (from-to)878-887
Number of pages10
JournalCell Death and Differentiation
Volume20
Issue number7
DOIs
StatePublished - Jul 2013

Fingerprint

Caspase 8
Autophagy
Hepatocytes
Galactosamine
Tumor Necrosis Factor-alpha
Liver
Wounds and Injuries
Lipopolysaccharides
Cell Death
Mitochondrial Degradation
Initiator Caspases
Caspase 7
Gene Knockout Techniques
In Situ Nick-End Labeling
Transferases
Alanine Transaminase
Caspase 3
Cytokines
Mortality

Keywords

  • Autophagy
  • Caspase-8
  • Lipopolysaccharide
  • Tumor necrosis factor

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology

Cite this

Inhibition of hepatocyte autophagy increases tumor necrosis factor-dependent liver injury by promoting caspase-8 activation. / Amir, M.; Zhao, E.; Fontana, L.; Rosenberg, H.; Tanaka, Kathryn E.; Gao, G.; Czaja, M. J.

In: Cell Death and Differentiation, Vol. 20, No. 7, 07.2013, p. 878-887.

Research output: Contribution to journalArticle

Amir, M. ; Zhao, E. ; Fontana, L. ; Rosenberg, H. ; Tanaka, Kathryn E. ; Gao, G. ; Czaja, M. J. / Inhibition of hepatocyte autophagy increases tumor necrosis factor-dependent liver injury by promoting caspase-8 activation. In: Cell Death and Differentiation. 2013 ; Vol. 20, No. 7. pp. 878-887.
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