S-nitrosylation of EMMPRIN influences the migration of HSCs and MMP activity in liver fibrosis: S-nitrosylation of EMMPRIN influences liver fibrosis

The mechanism of extracellular matrix metalloproteinase inducer (EMMPRIN) in the regulation of liver fibrosis has not been clarified. This study aims to investigate the role of EMMPRIN S-nitrosylation (SNO) in the regulation of hepatic stellate cell (HSC) migration and matrix metalloproteinase (MMP) activities in liver fibrosis. The results from the tissue microarrays and rat/mouse liver tissues suggest that EMMPRIN mRNA and protein levels in the fibrotic livers are lower than those in the corresponding normal control livers, but higher SNO level of EMMPRIN in fibrotic liver area was shown by immunohistochemistry, immunofluorescence staining, and biotin-switch assay conversely in vivo. Primary EMMPRIN comes from hepatocytes and liver sinus epithelial cells (LSECs) rather than quiescent HSCs. To mimic the uptake of extrinsic EMMPRIN, supernatants from mouse primary hepatocytes/293 cells transfected with EMMPRIN wild-type plasmids (WT) and EMMPRIN SNO site (cysteine 87) mutation plasmids (MUT) were collected and added to JS-1/LX2 cell medium. The MUT EMMPRIN diminishes SNO successfully, enhances the activities of MMP2 and MMP9, and subsequently increases HSC migration. In conclusion, SNO of EMMPRIN influences HSC migration and MMP activities in liver fibrosis. This finding may shed light on the possible regulatory mechanism of MMPs in ECM accumulation in liver fibrosis.