P53 Regulates Progression of Injury and Liver Regeneration After Acetaminophen Overdose

Liver regeneration in response to acetaminophen (APAP) overdose is a critical determinant of final patient outcome. Intricate cellular signaling during liver regeneration triggers liver cell proliferation, wound healing (if required) and restoration of liver mass and function. The p53 tumor suppressor protein is a critical regulator of cell cycle and apoptosis. However its role in liver regeneration after APAP overdose induced Acute Liver Failure (ALF) is not known. The pathogenesis of acute liver failure induced by APAP overdose can be divided into three phases including initiation of injury (formation of a reactive metabolite NAPQI and protein adducts) progression of injury (oxidative stress, mitochondrial and DNA damage resulting in necrosis) and regeneration/recovery phase (cell proliferation, angiogenesis and tissue repair). Here we show that p53 plays a critical role in inhibiting progression of injury and liver regeneration following APAP overdose mediated Acute Liver Injury (ALI). Eight‐week‐old male WT and p53KO mice (C57BL/6J background) were studied over time course of 0 to 96 hr following treatment with APAP300 (300mg/kg). Histology and serum ALT analysis showed similar liver injury in WT and p53KO mice at 1 and 12 hr however p53KO mice had significantly higher injury at 24 hr after APAP treatment. Interestingly, despite higher liver injury p53KO mice recovered equally to WT mice at 48 and 96 hr after APAP administration. Transcriptome analysis using liver RNA at 12, 24, 48hr from both groups revealed that p53KO mice had disrupted metabolic homeostasis, induced pro‐inflammatory and proliferative signaling. Further, molecular analysis of these pathways was done to confirm the findings. p53KO mice showed prolonged steatosis, lower mitochondrial DNA content, reduced expression of TFAM and mitochondrial complexes up to 24hr correlating with prolonged higher liver injury. p53 targets involved in fatty acid homeostasis, SREBP2 protein and GAMT mRNA expression correlated with prolonged steatosis in p53KO group. Liver regeneration determined by PCNA staining and cell cycle protein expression demonstrated that p53KO mice had rapid liver regeneration. Western blot analysis of EGFR, ERK and AKT showed sustained growth factor signaling in p53KO mice than WT mice after APAP treatment. These data illustrate that p53 has stage specific role during APAP‐induced ALF. p53 prevents progression of liver injury by maintaining mitochondrial and metabolic homeostasis after APAP overdose induced ALI. Further, p53 regulates initiation of liver regeneration through inflammatory and proliferative signaling after APAP overdose. These studies have revealed a novel role of p53 in acute liver injury pathogenesis. Support or Funding Information National Center for Research Resources (5P20RR021940‐07) Liver Scholar Award by AASLD/American Liver Foundation R01 DK098414