MiR-743a-3p-mediated hepatic GSTM1 elimination aggravates acetaminophen-induced acute liver injury by inhibiting Sp1 nuclear translocation and SIRT1 expression

Acetaminophen (APAP) overdose is a leading cause of drug-induced liver injury (DILI), and glutathione S-transferase mu 1 (GSTM1), a phase II enzyme involved in drug metabolism and detoxification, is associated with DILI incidence. However, the role of hepatic GSTM1 in APAP-induced liver injury is not fully understood. This study aimed to explore the role of hepatic GSTM1 in APAP-induced hepatotoxicity. A mouse model of APAP-induced liver injury was employed, and liver-specific GSTM1 and/or miR-743a-3p silencing was achieved via adeno-associated virus-8 (AAV8)-mediated RNA delivery. Our data showed that GSTM1 expression was significantly downregulated in APAP-treated mice. APAP induced miR-743a-3p upregulation, which directly suppressed GSTM1 expression, exacerbating liver injury, oxidative damage, and inflammation. Liver-specific miR-743a-3p knockdown rescued GSTM1 knockdown and mitigated liver injury. Mechanistically, GSTM1 interacted with Sp1 and promoted its S-glutathionylation. Loss of GSTM1 decreased Sp1 S-glutathionylation, impairing its nuclear translocation and transcriptional activity, which interfered with sirtuin 1 (SIRT1) expression. Activation of SIRT1 significantly alleviated GSTM1 knockdown-induced liver injury. Our findings suggest that miR-743a-3p-mediated GSTM1 silencing exacerbates APAP-induced liver injury through disruption of the GSTM1-Sp1-SIRT1 axis.