Autophagy, originally found in liver experiments, is a cellular process that degrades damaged organelle or protein aggregation. This process frees cells from various stress states is a cell survival mechanism under stress stimulation. It is now known that dysregulation of autophagy can cause many liver diseases. Therefore, how to properly regulate autophagy is the key to the treatment of liver injury. mechanistic target of rapamycin (mTOR)is the core hub regulating autophagy, which is subject to different upstream signaling pathways to regulate autophagy. This review summarizes three upstream pathways of mTOR: the phosphoinositide 3-kinase (PI3K)/protein kinase (AKT) signaling pathway, the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, and the rat sarcoma (Ras)/rapidly accelerated fibrosarcoma (Raf)/mitogen-extracellular activated protein kinase kinase (MEK)/ extracellular-signal-regulated kinase (ERK) signaling pathway, specifically explored their role in liver fibrosis, hepatitis B, non-alcoholic fatty liver, liver cancer, hepatic ischemia reperfusion and other liver diseases through the regulation of mTOR-mediated autophagy. Moreover, we also analyzed the crosstalk between these three pathways, aiming to find new targets for the treatment of human liver disease based on autophagy.

Steroid hormones are synthesized through enzymatic reactions using cholesterol as the substrate. In steroidogenic cells, the required cholesterol for steroidogenesis can be obtained from blood circulation or synthesized de novo from acetate. One of the key enzymes that control cholesterol synthesis is 24-dehydrocholesterol reductase (encoded by DHCR24). In humans and rats, DHCR24 is highly expressed in the adrenal gland, especially in the zona fasciculata. We recently reported that DHCR24 was expressed in the mouse adrenal gland’s inner cortex and also found that thyroid hormone treatment significantly upregulated the expression of Dhcr24 in the mouse adrenal gland. In the present study, we showed the cellular expression of DHCR24 in mouse adrenal glands in early postnatal stages. We found that the expression pattern of DHCR24 was similar to the X-zone marker gene 20αHSD in most developmental stages. This finding indicates that most steroidogenic adrenocortical cells in the mouse adrenal gland do not synthesize cholesterol locally. Unlike the 20αHSD-positive X-zone regresses during pregnancy, some DHCR24-positive cells remain present in parous females. Conditional knockout mice showed that the removal of Dhcr24 in steroidogenic cells did not affect the overall development of the adrenal gland or the secretion of corticosterone under acute stress. Whether DHCR24 plays a role in conditions where a continuous high amount of corticosterone production is needed requires further investigation.

Zearalenone (ZEA), a mycotoxin primarily generated by the Fusarium species, constitutes a prevalent contaminant in both human and animal feedstuffs. Chronic exposure to this mycotoxin induces hepatic inflammatory responses in livestock species including rabbits, ultimately leading to organ damage. Selenomethionine (SeMet), an organic selenium source recognized for its antioxidant properties and anti-inflammatory bioactivity, demonstrates protective benefits in animals through its detoxification mechanism and growth promotion. The present study investigated the protective effect of SeMet against ZEA-induced hepatic inflammation and elucidated its underlying mechanisms. Fifty healthy 90-day-old rabbits were randomly divided into five groups: control, ZEA-exposed and three SeMet-supplemented groups receiving 0.2, 0.35 or 0.5 mg/kg via dietary inclusion. After two weeks of SeMet pretreatment, ZEA administration (1.2 mg/kg B.W.) was imitated via oral gavage daily for one week in both the ZEA group and three SeMet-treated groups. As a result, ZEA exposure induced the significant structural disruption of the hepatic lobules, accompanied by increased collagen deposition, elevated pro-inflammatory cytokine profiles (IL-6, IL-1β, TNF-α) and reduced anti-inflammatory mediator levels (IL-10, TGF-β). SeMet supplementation alleviated ZEA-induced histological alterations, including inflammatory cell infiltration and collagen accumulation. Biochemical analysis indicated the restoration of inflammatory markers to near-normal levels when treated with SeMet. Notably, immunohistochemical results showed that SeMet significantly reduced the protein levels of IL-6 and its downstream target STAT3 under ZEA exposure. These findings indicated that SeMet attenuated ZEA-induced hepatic inflammation by modulating the IL-6/STAT3 signaling axis, with dietary supplementation of 0.35 mg/kg SeMet exhibiting the most significant effect on alleviating ZEA-induced hepatic inflammatory injury.