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.

LRG1 promotes epithelial-mesenchymal transition of retinal pigment epithelium cells by activating NOX4

AIM:To investigate the effect of leucine-rich-alpha-2-glycoprotein 1(LRG1)on epithelial-mesenchymal transition(EMT)in retinal pigment epithelium(RPE)cells,and to explore the role of NADPH oxidase 4(NOX4).METHODS:RPE cells(ARPE-19 cell line)were treated with transforming growth factor-β1(TGF-β1)to induce EMT.Changes of the m RNA and protein expression levels of LRG1 were tested in the TGF-β1 treated cells.The recombinant human LRG1 protein(r LRG1)and si RNA of LRG1 were used to establish accumulation of exogenous LRG1 model and the down-regulation of LRG1 model in ARPE-19 cells respectively,and to detect EMT-related markers including fibronectin,α-smooth muscle actin(α-SMA)and zonula occludens-1(ZO-1).The m RNA and protein expression level of NOX4 were measured according to the above treatments.VAS2870 was used as a NOX4 inhibitor in r LRG1-treated cells.EMT-related markers were detected to verify the effect of NOX4 in the process of EMT.RESULTS:TGF-β1 promoted the expression of LRG1 at both the m RNA and protein levels during the process of EMT which showed the up-regulation of fibronectin andα-SMA,as well as the down-regulation of ZO-1.Furthermore,the r LRG1 promoted EMT of ARPE-19 cells,which manifested high levels of fibronectin andα-SMA and low level of ZO-1,whereas knockdown of LRG1 prevented EMT by decreasing the expressions of fibronectin andα-SMA and increasing the expression of ZO-1 in ARPE-19 cells.Besides,the r LRG1 activated and LRG1 si RNA suppressed NOX4 expression.EMT was inhibited when VAS2870 was used in the r LRG1-treated cells.CONCLUSION:These results for the first time demonstrate that LRG1 promotes EMT of RPE cells by activating NOX4,which may provide a novel direction to explore the mechanisms of subretinal fibrosis.