title: Removal of acetaminophen protein adducts by autophagy protects against acetaminophen-induced liver injury in mice.
abstract: Acetaminophen (APAP)-induced liver injury is the most frequent cause of acute liver failure in the US and many other countries. Metabolism of APAP results in formation of APAP protein adducts (APAP-AD) in hepatocytes and triggers mitochondrial dysfunction and necrosis. However, the mechanisms for how APAP-AD are removed from hepatocytes remain unknown.
  
  
  
  Mice or primary hepatocytes were treated with APAP. APAP-AD were determined by immunoblot, immunostaining and high pressure liquid chomatography with electrochemical detection analysis.
  
  
  
  We found that APAP-AD were detected at 1h, peaked at approximately 2h, declined at 6h and almost full removed at 24h post treatment with APAP in mouse livers and in primary mouse hepatocytes. APAP-AD displayed a punctate pattern and were colocalized with GFP-LC3 positive autophagosomes and Lamp1 positive lysosomes in APAP-treated primary hepatocytes. Moreover, isolated autophagosomes and autolysosomes from APAP-treated mouse livers contained APAP-AD, suggesting autophagy may selectively remove APAP-AD. APAP-AD were detected in both detergent soluble and insoluble pools in APAP-treated mouse livers and hepatocytes. More importantly, pharmacological inhibition of autophagy by leupeptin or chloroquine increased whereas induction of autophagy by Torin 1 decreased serum APAP-AD levels in APAP-treated mice, which correlated with alanine aminotransferase levels and liver necrosis. Furthermore, SQSTM1/p62, an autophagy receptor protein, was recruited to APAP-AD. Adenovirus-mediated shRNA knockdown of SQSTM1/p62 led to increased APAP-AD and necrosis in primary hepatocytes.
  
  
  
  Our data indicate that APAP-AD are removed though selective autophagy. Pharmacological induction of autophagy may be a novel promising approach for treating APAP-induced liver injury.
  
  
  
  Acetaminophen overdose can form acetaminophen protein adducts and mitochondria damage in hepatocytes resulting in liver injury. Activation of autophagy-lysosomal degradation pathway can help to remove acetaminophen protein adducts. Pharmacological induction of autophagy may be a novel promising approach for treating APAP-induced liver injury.
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Hong-Min
authors.initials: HM
authors.lastname: Ni
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Mitchell R
authors.initials: MR
authors.lastname: McGill
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Chao
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Kuo
authors.initials: K
authors.lastname: Du
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Williams
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Yuchao
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Jaeschke
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA. Electronic address: wxding@kumc.edu.
authors.forename: Wen-Xing
authors.initials: WX
authors.lastname: Ding
mesh_terms: D000082:Acetaminophen; D000818:Animals; D001343:Autophagy; D056486:Chemical and Drug Induced Liver Injury; D022781:Hepatocytes; D008099:Liver; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D000082:Acetaminophen
keywords: Acetaminophen; Acetaminophen protein adducts; Autophagy; Liver injury; p62/SQSTM1