Hepatocyte-specific MET deletion exacerbates acetaminophen-induced hepatotoxicity in mice

Despite the well-known role of MET in liver regeneration following partial-hepatectomy (PHx), its role in the clinically-relevant acetaminophen (APAP)-induced liver injury (AILI) model remains unexplored. AILI markedly differs from PHx because it is associated with massive liver necrosis. This study aims to delineate the role of MET specifically in AILI. Hepatocyte-specific MET-KO mice were given a toxic-dose of APAP and assessed for hepatotoxicity/regeneration parameters. MET deletion strikingly exacerbated initial hepatotoxicity and impaired subsequent proliferative response, culminating in significant mortality. Mechanistically, MET deletion enhanced JNK-activation and its mitochondrial translocation, resulting in excessive mitochondrial oxidative-damage, releasing cell-death inducer AIF into cytosol. Excess JNK-activation was attributed to reduced inhibitory activity of AKT on JNK in the absence of MET-signaling. Pharmacological activation of AKT reduced JNK-activation and hepatotoxicity in MET-KO mice. RNA-sequencing/immunoblotting not only showed repression of proliferative/survival signaling, but also activation of cell death/senescence pathways along with impaired unfolded-protein-response in MET-KO mice. Analysis of published single-nucleus RNA-sequencing data showed proliferation in livers from APAP-induced ALF patients was associated with strong activation of HGF/MET signaling in hepatocytes, with spatial-transcriptomics showing striking induction of HGF surrounding the necrotic-zones. Interestingly, 35% of the genes altered in human-ALF were regulated by MET in the mouse AILI-model. In conclusion, our study demonstrates that MET is crucial for restraining hepatotoxicity following APAP overdose via inhibiting mitochondrial cell-death signaling pathway.