Hepatocyte Specific Deletion of Yes-Associated Protein (YAP) Improves Recovery from Acetaminophen-Induced Acute Liver Injury.

Overdose of acetaminophen (APAP) is the major cause of acute liver failure in the Western world with very limited treatment options. Previous studies from our groups and others have shown that timely activation of liver regeneration is a critical determinant of transplant free survival of APAP-induced acute liver failure (ALF) patients. Here we report that hepatocyte specific deletion of Yes associated protein (Yap), the downstream mediator of the Hippo Kinase signaling pathway results in faster recovery from APAP-induced acute liver injury (ALI). Initial studies performed with male C57BL/6J mice showed a rapid activation of Yap and its target genes within first 24 hours after APAP administration. Treatment of hepatocyte specific Yap knockout mice (Yap-KO) with 300 mg/kg APAP resulted in equal initial liver injury but a significantly accelerated recovery in Yap-KO mice. The recovery was accompanied by significantly rapid hepatocyte proliferation supported by faster activation of Wnt/β-catenin pathway. Furthermore, Yap-KO mice had significantly earlier and higher pro-regenerative inflammatory response following APAP overdose. Global gene expression analysis indicated that Yap-KO mice had a robust activation of transcription factors involved in response to ER stress (XBP1) and maintaining hepatocyte differentiation (HNF4α). In conclusion, these data indicate that inhibition of Yap in hepatocytes results in rapid recovery from APAP overdose due to an earlier activation of liver regeneration.