Abstract

Background: Macroautophagy (referred to as autophagy hereafter) is a major intracellular lysosomal degradation pathway that is responsible for the degradation of misfolded/damaged proteins and organelles. Previous studies showed that autophagy protects against acetaminophen (APAP)-induced injury (AILI) via selective removal of damaged mitochondria and APAP protein adducts. The lysosome is a critical organelle sitting at the end stage of autophagy for autophagic degradation via fusion with autophagosomes.The goal of this study was to investigate the role and mechanisms of transcription factor EB (TFEB)-mediated lysosomal and mitochondria biogenesis in AILI.

Methods: Wildtype mice, liver-specific TFEB knockout mice or mice with hepatic overexpression of TFEB using Adenovirus-Tfeb were treated with APAP for various time points. Serum alanine aminotransferase (ALT) levels, liver histology and TUNEL staining as well as RNA sequencing and western blot analysis were performed. A cell-based imaging high-throughput chemical screening for TFEB agonists using a stable GFP-TFEB AML12 cell line was also performed.

Results: We showed that TFEB was impaired by APAP resulting in decreased lysosomal biogenesis in mouse livers, which was associated with levels of APAP-adducts and liver injury. Genetic loss-of and gain-of function of hepatic TFEB exacerbated or protected against AILI, respectively. Mechanistically, overexpression of TFEB increased clearance of APAP protein adducts and mitochondria biogenesis as well as SQSTM1/p62-dependent non-canonical nuclear factor erythroid 2-related factor 2 (NRF2) activation and hepatic glutathione biosynthesis to protect against AILI. Cell-based imaging high-throughput chemical screening identified a group of TFEB agonists. Among these agonists, salinomycin, an anticoccidial and antibacterial agent, activated TFEB and protected against AILI in mice.

Conclusion: In conclusion, genetic and pharmacological activating TFEB promotes removal of APAP-adducts and damaged mitochondria with concurrent increased mitochondrial biogenesis, which may be a promising approach for improving recovery of AILI.