Dual roles of p62/SQSTM1 in the injury and recovery phases of acetaminophen-induced liver injury in mice

Abstract

Acetaminophen (APAP) overdose can induce liver injury and is the most frequent cause of acute liver failure in the United States. We investigated the role of p62/SQSTM1 (referred to as p62) in APAP-induced liver injury (AILI) in mice. We found that the hepatic protein levels of p62 dramatically increased at 24 h after APAP treatment, which was inversely correlated with the hepatic levels of APAP-adducts. APAP also activated mTOR at 24 h, which is associated with increased cell proliferation. In contrast, p62 knockout (KO) mice showed increased hepatic levels of APAP-adducts detected by a specific antibody using Western blot analysis but decreased mTOR activation and cell proliferation with aggravated liver injury at 24 h after APAP treatment. Surprisingly, p62 KO mice recovered from AILI whereas the wild-type mice still sustained liver injury at 48 h. We found increased number of infiltrated macrophages in p62 KO mice that were accompanied with decreased hepatic von Willebrand factor (VWF) and platelet aggregation, which are associated with increased cell proliferation and improved liver injury at 48 h after APAP treatment. Our data indicate that p62 inhibits the late injury phase of AILI by increasing autophagic selective removal of APAP-adducts and mitochondria but impairs the recovery phase of AILI likely by enhancing hepatic blood coagulation.

Keywords: 4EBP-1, translational initiation factor 4E binding protein-1; AILI, APAP-induced liver injury; ALT, alanine aminotransferase; APAP, acetaminophen; APAP-AD, APAP-adducts; Autophagy; CLEC-2, C-type lectin-like receptor; CYP2E1, cytochrome P450 2E; Coagulation; DILI; GCL, glutamate cysteine ligase; GSH, glutathione; H&E, hematoxylin and eosin; Hepatotoxicity; KC, Kupffer cells; KEAP1, Kelch-like ECH-associated protein-1; KIR, KEAP1-interacting region; KO, knockout; LC3, microtubule-associated light chain 3; Liver regeneration; Macrophage; NAC, N-acetylcysteine; NAPQI, N-acetyl-p-benzoquinone imine; NF-κB, nuclear factor-κB; NPCs, non-parenchymal cells; NQO1, NADPH quinone dehydrogenase 1; NRF2, nuclear factor erythroid 2-related factor 2; Platelet; S6, ribosomal protein S6 kinase; TUNEL, terminal deoxynucleotidyl transferase dUTP nick end labeling; VWF, von Willebrand factor; WT, wild type.