High-throughput screening of novel TFEB agonists in protecting against acetaminophen-induced liver injury in mice

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. In the present study, we showed that transcription factor EB (TFEB), a master transcription factor for lysosomal biogenesis, was impaired by APAP resulting in decreased lysosomal biogenesis in mouse livers. 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 to protect against AILI. We also performed an unbiased cell-based imaging high-throughput chemical screening on TFEB and identified a group of TFEB agonists. Among these agonists, salinomycin, an anticoccidial and antibacterial agent, activated TFEB and protected against AILI in mice. In conclusion, genetic and pharmacological activating TFEB may be a promising approach for protecting against AILI.

Autophagy and liver cancer

Autophagy is a highly conserved catabolic process that degrades cytosolic proteins and organelles via formation of autophagosomes that fuse with lysosomes to form autolysosomes, whereby autophagic cargos are degraded. Numerous studies have demonstrated that autophagy plays a critical role in the regulation of liver physiology and homeostasis, and impaired autophagy leads to the pathogenesis of various liver diseases such as viral hepatitis, alcohol associated liver diseases (AALD), non-alcoholic fatty liver diseases (NAFLD), and liver cancer. Recent evidence indicates that autophagy may play a dual role in liver cancer: inhibiting early tumor initiation while promoting progression and malignancy of already formed liver tumors. In this review, we summarized the progress of current understanding of how hepatic viral infection, alcohol consumption and diet-induced fatty liver diseases impair hepatic autophagy. We also discussed how impaired autophagy promotes liver tumorigenesis, and paradoxically how autophagy is required to promote the malignancy and progression of liver cancer. Understanding the molecular mechanisms underlying how autophagy differentially affects liver cancer development and progression may help to design better therapeutic strategies for prevention and treatment of liver cancer.

Regulatory effects of the bile acid membrane receptor TGR5 on FN and TGF-β1 in rat glomerular mesangial cells cultured under high glucose condition / 中国药理学通报

Aim To investigate the expression of G protein-coupled receptor TGR5 and its effects on FN and TGF-β1 expression cultured under high glucose condition in rat glomerular mesangial cells , and then to explore the role of TGR5 in diabetic nephropathy. Methods INT-777 and TGR5 plasmid were used to activate TGR5 under high glucose(HG,30 mmol·L - 1 glucose ) condition, and anti-TGR5 small interfering RNA(TGR5 siRNA) was used to knock down TGR5. The protein expression of FN and TGF-β1 in rat me-sangial cells was detected by Western blot. Results TGR5 could be detected in rat glomerular mesangial cells. Both FN and TGF-β1 protein levels could be in-creased by high glucose compared with control group(P < 0. 05),and be inhibited by activiation of TGR5(P <0. 05). On the other hand,knockdown of TGR5 could increase FN and TGF-β1 protein to abnormal levels(P< 0. 01,P < 0. 05). Conclusion TGR5 suppresses HG-induced FN and TGF-β1 expression in rat glomer-ular mesangial cells,suggesting a protective role in the process of diabetic nephropathy.