Hippo(YAP)-autophagy axis protects against hepatic ischemia-reperfusion injury through JNK signaling

Background:Hepatic ischemia-reperfusion injury(HIRI)remains a common complication during liver transplantation(LT)in patients.As a key downstream effector of the Hippo pathway,Yes-associated protein(YAP)has been reported to be involved in various physiological and pathological processes.However,it remains elusive whether and how YAP may control autophagy activation during ischemia-reperfusion.Methods:Human liver tissues from patients who had undergone LT were obtained to evaluate the correlation between YAP and autophagy activation.Both an in vitro hepatocyte cell line and in vivo liver-specific YAP knockdown mice were used to establish the hepatic ischemia-reperfusion models to determine the role of YAP in the activation of autophagy and the mechanism of regulation.Results:Autophagy was activated in the post-perfusion liver grafts during LT in patients,and the expression of YAP positively correlated with the autophagic level of hepatocytes.Liver-specific knockdown of YAP inhibited hepatocytes autophagy upon hypoxia-reoxygenation and HIRI(P<0.05).YAP deficiency aggravated HIRI by promoting the apoptosis of hepatocytes both in the in vitro and in vivo models(P<0.05).Attenuated HIRI by overexpression of YAP was diminished after the inhibition of autophagy with 3-methyladenine.In addition,inhibiting autophagy activation by YAP knockdown exacerbated mitochondrial damage through increasing reactive oxygen species(P<0.05).Moreover,the regulation of autophagy by YAP during HIRI was mediated by AP1(c-Jun)N-terminal kinase(JNK)signaling through binding to the transcriptional enhanced associate domain(TEAD).Conclusions:YAP protects against HIRI by inducing autophagy via JNK signaling that suppresses the apoptosis of hepatocytes.Targeting Hippo(YAP)-JNK-autophagy axis may provide a novel strategy for the prevention and treatment of HIRI.