Effect of autophagy-associated proteins on the arecoline-induced liver injury in mice

A toxicological review of alkaloids

Alkaloids are naturally occurring compounds with complex structures found in natural plants. To further improve the understanding of plant alkaloids, this review focuses on the classification, toxicity and mechanisms of action, providing insight into the occurrence of alkaloid-poisoning events and guiding the safe use of alkaloids in food, supplements and clinical applications. Based on their chemical structure, alkaloids can be divided into organic amines, diterpenoids, pyridines, isoquinolines, indoles, pyrrolidines, steroids, imidazoles and purines. The mechanisms of toxicity of alkaloids, including neurotoxicity, hepatoxicity, nephrotoxicity, cardiotoxicity and cytotoxicity, have also been reviewed. Some cases of alkaloid poisoning have been introduced when used as food or clinically, including accidental food poisoning, excessive consumption, and poisoning caused by the improper use of alkaloids in a clinical setting, and the importance of safety evaluation was illustrated. This review summarizes the toxicity and mechanism of action of alkaloids and provides evidence for the need for the safe use of alkaloids in food, supplements and clinical applications.

Vasorin Deletion in C57BL/6J Mice Induces Hepatocyte Autophagy through Glycogen-Mediated mTOR Regulation

Abnormal vasorin (Vasn) expression occurs in multiple diseases, particularly liver cancers. Vasn knockout (KO) in mice causes malnutrition, a shortened life span, and decreased physiological functions. However, the causes and underlying mechanisms remain unknown. Here, we established Vasn KO C57BL/6J mice by using the CRISPR/Cas9 system. The animals were weighed, and histology, immunohistochemistry, electronic microscopy, and liver function tests were used to examine any change in the livers. Autophagy markers were detected by Western blotting. MicroRNA (miRNA) sequencing was performed on liver samples and analyses to study the signaling pathway altered by Vasn KO. Significant reductions in mice body and liver weight, accompanied by abnormal liver function, liver injury, and reduced glycogen accumulation in hepatocytes, were observed in the Vasn KO mice. The deficiency of Vasn also significantly increased the number of autophagosomes and the expression of LC3A/B-II/I but decreased SQSTM1/p62 levels in hepatocytes, suggesting aberrant activation of autophagy. Vasn deficiency inhibited glycogen-mediated mammalian target of rapamycin (mTOR) phosphorylation and activated Unc-51-like kinase 1 (ULK1) signaling, suggesting that Vasn deletion upregulates hepatocyte autophagy through the mTOR-ULK1 signaling pathway as a possible cause of diminished life span and health. Our results indicate that Vasn is required for the homeostasis of liver glycogen metabolism upstream of hepatocyte autophagy, suggesting research values for regulating Vasn in pathways related to liver physiology and functions. Overall, this study provides new insight into the role of Vasn in liver functionality.

Mitofusin2, a rising star in acute-on-chronic liver failure, triggers macroautophagy via the mTOR signalling pathway

Acute-on-chronic liver failure (ACLF) is a life-threatening syndrome with poor prognosis. Several studies have begun to prove that mitochondria play a crucial role in liver failure. Mitofusin2 (Mfn2) plays a key role in maintaining the integrity of mitochondrial morphology and function. However, the role and underlying mechanisms of Mfn2 on cell autophagy of ACLF remain unclear. Our aim was to explore the effect of Mfn2 on several biological functions involving cell autophagy in ACLF. In this study, we constructed an ACLF animal model and a hepatocyte autophagy model, using adenovirus and lentivirus to deliver Mfn2 to liver cells, in order to assess the effect of Mfn2 on autophagy and apoptosis in ACLF. Furthermore, we explored the biological mechanism of Mfn2-induced autophagy of ACLF using Western blotting, RT-PCR and electron microscopy. We found that Mfn2 significantly attenuated ACLF, characterized by ameliorated gross appearance and microscopic histopathology of liver, and reduced serum AST, ALT, and TBIL levels. Mfn2 improved the expressions of LC3-II, Atg5 and Bcl-2 and down-regulated the expression of P62 and Bax in ACLF. Like rapamycin, Mfn2 also significantly inhibited the expressions of p-PI3K, p-Akt and p-mTOR in ACLF. In conclusion, our findings suggest that Mfn2 influences multiple biological functions of ACLF via the PI3K/Akt/mTOR signalling pathway. This study will provide a reliable theoretical basis for the application of Mfn2 as an effective target for ACLF treatment, reversing or delaying the process of ACLF.