Integrated stress response promotes acute liver failure by activating SETD7 and enhancing NLRP3 methylation

While suppression of the integrated stress response (ISR) has been shown to restore proteostasis and mitigate organ injury in various diseases, its role in acute liver failure (ALF) remains poorly defined. Here, we discovered that, during drug-induced ALF, hepatocytes exhibited early and transient activation of the eIF2α-ATF4 signaling pathway, whereas macrophages displayed delayed but sustained activation. Hepatocyte-specific deletion of ATF4 (ATF4^ΔHep) significantly protected mice from acetaminophen (APAP)-induced liver injury, whereas myeloid-specific ATF4 deletion (ATF4^ΔMye) increased susceptibility. Protection in ATF4^ΔHep mice was associated with reduced hepatic necrosis, apoptosis, neutrophil infiltration, proinflammatory cytokine production, and serum alanine aminotransferase (ALT)/aspartate aminotransferase (AST) levels. Pharmacological inhibition of the ISR using ISR inhibitor (ISRIB) similarly ameliorated ALF, underscoring its therapeutic potential and the stage-dependent dual role of ISR signaling. Mechanistically, ATF4 in hepatocytes promoted mitochondrial dysfunction and inflammatory responses via the SETD7-NLRP3/interleukin-1β (IL-1β) axis. ATF4 transcriptionally upregulated SETD7, a non-histone methyltransferase that methylates NLRP3 at residues K192 and K684 within the NACHT (named after conserved sequences found in NAIP [neuronal apoptosis inhibitory protein], CIITA [MHC class II transactivator], HET-E [incompatibility locus protein from Podospora anserina], and TP1 [telomerase-associated protein 1]) and Leucine-Rich Repeat (LRR) domains, stabilizing NLRP3 and enhancing inflammasome activation. The biphasic role of ATF4 was further validated in a carbon tetrachloride (CCl₄)-induced acute liver injury model. These findings identify the ATF4-SETD7-NLRP3 axis as a key regulator of hepatic inflammasome homeostasis and suggest it as a promising therapeutic target for ALF treatment.