hMSCs-derived exosome circCDK13 inhibits liver fibrosis by regulating the expression of MFGE8 through miR-17-5p/KAT2B.

OBJECTIVE: To investigate the effects of human bone marrow mesenchymal stem cells (hMSCs)-derived exosome circCDK13 on liver fibrosis and its mechanism. METHODS: Exosomes derived from hMSCs were extracted and identified by flow cytometry and osteogenic and adipogenic induction, and the expressions of marker proteins on the surface of exosomes were detected by western blot. Cell proliferation was measured by CCK8 assay, the expression of active markers of HSCs by immunofluorescence, and the expressions of fibrosis-related factors by western blot. A mouse model of liver fibrosis was established by intraperitoneal injection of thioacetamide (TAA). Fibrosis was detected by HE staining, Masson staining, and Sirius red staining. Western blot was utilized to test the expressions of PI3K/AKT and NF-κB pathway related proteins, dual-luciferase reporter assay and RIP assay to validate the binding between circCDK13 and miR-17-5p as well as between miR-17-5p and KAT2B, and ChIP to validate the effect of KAT2B on H3 acetylation and MFGE8 transcription. RESULTS: hMSCs-derived exosomes inhibited liver fibrosis mainly through circCDK13. Dual-luciferase reporter assay and RIP assay demonstrated the binding between circCDK13 and miR-17-5p as well as between miR-17-5p and KAT2B. Further experimental results indicated that circCDK13 mediated liver fibrosis by regulating the miR-17-5p/KAT2B axis, and KAT2B promoted MFGE8 transcription by H3 acetylation. Exo-circCDK13 inhibited PI3K/AKT and NF-κB signaling pathways activation through regulating the miR-17-5p/KAT2B axis. CONCLUSION: hMSCs-derived exosome circCDK13 inhibited liver fibrosis by regulating the expression of MFGE8 through miR-17-5p/KAT2B axis.

microRNA-122 inhibits hepatic stellate cell proliferation and activation in vitro and represses carbon tetrachloride-induced liver cirrhosis in mice.

OBJECTIVE: This study aimed to determine the roles of microRNA (miR)-122 in the activation of hepatic stellate cells (HSCs) and liver cirrhosis. METHODS: Rat primary HSCs were incubated with transforming growth factor-beta (TGF-ß), during which miR-122 and EphB2 expression was measured. miR-122 mimic and/or pcDNA3.1 EphB2 was transfected into TGF-ß-induced HSCs. A mouse model of liver cirrhosis was established via an intraperitoneal injection of carbon tetrachloride (CCl4), followed by the injection of miR-122 agomir. Levels of serum alanine transaminase (ALT) and aspartate aminotransferase (AST) were measured. Fibronectin (FN), alpha smooth muscle actin (α-SMA), Collagen I, miR-122, and EphB2 expression was evaluated in liver tissues and HSCs. Cell proliferation was measured using CCK-8 assay. Interactions between miR-122 and EphB2 were assessed using dual luciferase reporter assay. RESULTS: miR-122 (0.15-fold) was downregulated and EphB2 (mRNA: 5.06-fold; protein: 2.35-fold) was upregulated after TGF-ß induction of HSCs. Overexpressed miR-122 decreased proliferation and EphB2 (mRNA: 0.46-fold; protein: 0.62-fold), FN (mRNA: 0.45-fold; protein: 0.64-fold), α-SMA (mRNA: 0.48-fold; protein: 0.51-fold), and Collagen I (mRNA: 0.44-fold; protein: 0.51-fold) expression in HSCs, which was abrogated by EphB2 upregulation. miR-122 expression was reduced by 0.21-fold and serum ALT and AST levels were enhanced in mice following 8-week CCl4 induction along with increased expression of FN, α-SMA, and Collagen I in liver tissues, which was blocked by miR-122 overexpression. Moreover, EphB2 was a target gene of miR-122. CONCLUSION: miR-122 curtails HSC proliferation and activation by targeting EphB2 and suppresses liver cirrhosis in mice.