Zinc-α2-glycoprotein 1 attenuates non-alcoholic fatty liver disease by negatively regulating tumour necrosis factor-α

BACKGROUND Zinc-α2-glycoprotein 1 (AZGP1) plays important roles in metabolism-related diseases. The underlying molecular mechanisms and therapeutic effects of AZGP1 remain unknown in non-alcoholic fatty liver disease (NAFLD). AIM To explore the effects and potential mechanism of AZGP1 on NAFLD in vivo and in vitro. METHODS The expression of AZGP1 and its effects on hepatocytes were examined in NAFLD patients, CCl4-treated mice fed a high fat diet (HFD), and human LO2 cells. RESULTS AZGP1 levels were significantly decreased in liver tissues of NAFLD patients and mice. AZGP1 knockdown was found to activate inflammation;enhance steatogenesis, including promoting lipogenesis [sterol regulatory elementbinding protein (SREBP)-1c, liver X receptor (LXR), fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), and stearoyl CoA desaturase 1 (SCD)-1], increasing lipid transport and accumulation [fatty acid transport protein (FATP), carnitine palmitoyl transferase (CPT)-1A, and adiponectin], and reducing fatty acid β-oxidation [farnesoid X receptor (FXR) and peroxisome proliferator-activated receptor (PPAR)-α];accelerate proliferation;and reverse apoptosis in LO2 cells. AZGP1 overexpression (OV-AZGP1) had the opposite effects. Furthermore, AZGP1 alleviated NAFLD by blocking TNF-α-mediated inflammation and intracellular lipid deposition, promoting proliferation, and inhibiting apoptosis in LO2 cells. Finally, treatment with OV-AZGP1 plasmid dramatically improved liver injury and eliminated liver fat in NAFLD mice. CONCLUSION AZGP1 attenuates NAFLD with regard to ameliorating inflammation, accelerating lipolysis, promoting proliferation, and reducing apoptosis by negatively regulating TNF-α. AZGP1 is suggested to be a novel promising therapeutic target for NAFLD.

MicroRNA-194 inactivates hepatic stellate cells and alleviates liver fibrosis by inhibiting AKT2

BACKGROUND Activation of hepatic stellate cells(HSCs)is a pivotal event in the onset and progression of liver fibrosis.Loss of microRNA-194(miR-194)has been reported in activated HSCs,but the actual role of miR-194 in liver fibrosis remains uncertain.AIM To explore the role and potential mechanism of miR-194-mediated regulation of liver fibrosis in vitro and in vivo.METHODS The expression of miR-194 was examined in human fibrotic liver tissues,activated HSCs,and a carbon tetrachloride(CCl4)mouse model by qPCR.The effects of AKT2 regulation by miR-194 on the activation and proliferation of HSCs were assessed in vitro.For in vivo experiments,we reintroduced miR-194 in mice using a miR-194 agomir to investigate the functions of miR-194 in liver fibrosis.RESULTS MiR-194 expression was notably lacking in activated HSCs from both humans and mice.Overexpression of miR-194(OV-miR-194)inhibitedα-smooth muscle actin(α-SMA)and type I collagen(Col I)expression and suppressed cell proliferation in HSCs by causing cell cycle arrest in G0/G1 phase.AKT2 was predicted to be a target of miR-194.Notably,the effects of miR-194 knockdown in HSCs were almost blocked by AKT2 deletion,indicating that miR-194 plays a role in HSCs via regulation of AKT2.Finally,miR-194 agomir treatment dramatically ameliorated liver fibrosis in CCl4-treated mice.CONCLUSION We revealed that miR-194 plays a protective role by inhibiting the activation and proliferation of HSCs via AKT2 suppression.Our results further propose miR-194 as a potential therapeutic target for liver fibrosis.

Lipotoxic hepatocyte-derived exosomal miR-1297 promotes hepatic stellate cell activation through the PTEN signaling pathway in metabolic-associated fatty liver disease

BACKGROUND Exosomes play an important role in metabolic-associated fatty liver disease(MAFLD),but the mechanism by which exosomes participate in MAFLD still remain unclear.AIM To figure out the function of lipotoxic exosomal miR-1297 in MAFLD.METHODS MicroRNA sequencing was used to detect differentially expressed miRNAs(DEmiR)in lipotoxic exosomes derived from primary hepatocytes.Bioinformatic tools were applied to analyze the target genes and pathways regulated by the DE-miRs.Quantitative real-time PCR(qPCR)was conducted for the verification of DEmiRs.qPCR,western blot,immunofluorescence staining and ethynyl-20-deoxyuridine assay were used to evaluate the function of lipotoxic exosomal miR-1297 on hepatic stellate cells(LX2 cells).A luciferase reporter experiment was performed to confirm the relationship of miR-1297 and its target gene PTEN.RESULTS MicroRNA sequencing revealed that there were 61 exosomal DE-miRs(P<0.05)with a fold-change>2 from palmitic acid treated primary hepatocytes compared with the vehicle control group.miR-1297 was the most highly upregulated according to the microRNA sequencing.Bioinformatic tools showed a variety of target genes and pathways regulated by these DE-miRs were related to liver fibrosis.miR-1297 was overexpressed in exosomes derived from lipotoxic hepatocytes by qPCR.Fibrosis promoting genes(α-SMA,PCNA)were altered in LX2 cells after miR-1297 overexpression or miR-1297-rich lipotoxic exosome incubation via qPCR and western blot analysis.Immunofluorescence staining and ethynyl-20-deoxyuridine staining demonstrated that the activation and proliferation of LX2 cells were also promoted after the above treatment.PTEN was found to be the target gene of miR-1297 and knocking down PTEN contributed to the activation and proliferation of LX2 cells via modulating the PI3K/AKT signaling pathway.CONCLUSION miR-1297 was overexpressed in exosomes derived from lipotoxic hepatocytes.The lipotoxic hepatocyte-derived exosomal miR-1297 could promote the activation and proliferation of hepatic stellate cells through the PTEN/PI3K/AKT signaling pathway,accelerating the progression of MAFLD.