Knockdown of N-Acetylglucosaminyl Transferase V Ameliorates Hepatotoxin-Induced Liver Fibrosis in Mice

Aberrant N-glycosylation caused by altered N-acetyl glucosaminyltransferase V (GnT-V) expression is known to regulate tumor invasion and metastasis by modulating multiple cytokine signaling pathways. However, the exact role of GnT-V in the development of liver fibrosis has not been clearly defined. Here, we induced mouse liver fibrosis by ip injections of carbon tetrachloride (CCl4) or thioacetamide (TAA) and observed significant increase of hepatic GnT-V during the processes of liver fibrogenesis. Meanwhile, upregulations of GnT-V were detected in the activated hepatic stellate cells (HSCs) and injured hepatocytes. To knock down hepatic GnT-V expression, adenovirus that expressed the GnT-V siRNA was injected via the tail vein. Adenovirus-mediated delivery of GnT-V siRNA dramatically reduced the GnT-V expression in fibrotic liver and activated HSC in vivo and consequently alleviated CCl4- or TAA-induced liver fibrosis as assessed through collagen deposition and profiles of profibrogenic markers. Furthermore, knockdown of GnT-V in HSCs reduced transforming growth factor beta (TGF-β)/Smad signaling and blunted the activated HSC phenotype. The suppression of TGF-β/Smad signaling in HSCs correlated with the decrease of GnT-V-modified β1,6-branched N-glycan on TGF-β receptors. Knockdown of GnT-V also suppressed platelet-derived growth factor (PDGF)-induced HSC proliferation and migration through inhibiting PDGF/Erk signaling. Finally, we demonstrated that knockdown of GnT-V profoundly suppressed TGF-β1-induced epithelial-mesenchymal transition (EMT) in hepatocytes by morphological assessment and reversal of EMT markers. In conclusion, this study demonstrates that GnT-V is implicated in hepatotoxin-induced liver fibrosis, and targeting GnT-V may be a feasible and promising approach for treating liver fibrosis.