CircRNA608-microRNA222-PINK1 axis regulates the mitophagy of hepatic stellate cells in NASH related fibrosis

Background Increasing evidences have confirmed the relationship between mitophagy and nonalcoholic steatohepatitis (NASH). The exact mechanism of upstream circular RNAs (circRNAs) regulating PTEN-induced putative kinase 1 (PINK1) mediated mitophagy and its contribution to NASH-related liver fibrosis was explored in our study. Methods Primary hepatic stellate cells (PHSCs) from C57BL/6 mice transfected with small interfering RNAs against PINK1 (si-PINK1) and negative control (si-NC) were prepared to perform circRNA sequence. Differentially expressed circRNAs, bioinformatic analysis and predicting software were performed to select axis of circ608/miR-222/PINK1. The expressions of circ608/miR-222/PINK1 were verified by RT-qPCR. The mitochondrial function was evaluated by immunofluorescence staining of COX4 and LC3B. Results PINK1-mediated mitophagy was inhibited in NASH-related liver fibrosis mice. CircRNA sequence revealed there were 37 DE-circRNAs between si-PINK1 PHSCs and si-NC PHSCs. Bioinformatic analysis showed these DE-circRNAs were related to enriched signaling pathways (such as Wnt, Rap1, mTOR, Hippo) regulating liver fibrosis and mitophagy. Circ608 was significantly down-regulated in lipotoxic HSCs and in livers of NASH-related liver fibrosis mice. MiR222 was identified to be the target miRNA of circ608 and was negatively regulated by circ608 in lipotoxic HSCs. MiR222 also had a binding site with PINK1 and could negatively regulate PINK1. So, the axis of circ608-miR222-PINK1 was proved to participate in NASH-related liver fibrosis by regulating mitophagy. These results illustrated that circ608 might promote PINK1-mediated mitophagy though inhibiting miR222 in lipotoxic HSCs. Conclusion Circ608 could promote PINK1-mediated mitophagy of HSCs though inhibiting miR222 in NASH-related liver fibrosis.