PE-018 : Autophagy Regulates the Expression of CTGF

Abstract

Aims: Autophagy is an intracellular lysosomal degradation pro cess that performs important cell functions in the liver. Several studies have shown that hepatocyte-specific ATG7 or ATG5 knockout mice have increased liver injury, including liver fibro sis. However, the relationship between autophagy and liver injury and fibrosis has not been clarified so far. In this study, we investigated the genes associated with autophagy inhibition and hepatic fibrosis. Methods: Hepatocyte-specific ATG7 knockout mice were gen erated by crossing ATG7 Flox/Flxo mice with albumin Cre mice. We isolated and cultured ATG7 K/O mouse primary hepatocyte, mouse hepatocyte and human hepatic stellate cell lines (AML12, LX2) and rat kidney fibroblast and mouse mesangial cell lines (NRK49F, SV40 MES 13). We used bafilomycin A or chloroquine as an autophagy inhibitor and MG132 as an autophagy induc er. The expression levels of CTGF, LC3, p62 and MAPK were evaluated by western blot analysis. Results: Primary hepatocyte isolated from hepatocyte-specific ATG7 knockout mice showed increased expression of CTGF and phospho-ERK. MG132 decreased CTGF expression and BFM or CQ increased CTGF and phospho-ERK expression. In addition, increased CTGF expression by BFM or CQ was reduced by ERK inhibitor. Conclusions: These results suggest that inhibition of autoph agy may increase the expression of CTGF and ERK, while the increase of autophagy decreases the expression of CTGF. This suggests that autophagy may be involved in the progression of fibrosis.