Published online Apr 14, 2021. doi: 10.3748/wjg.v27.i14.1419
Peer-review started: October 10, 2020
First decision: January 23, 2021
Revised: February 5, 2021
Accepted: March 7, 2021
Article in press: March 7, 2021
Published online: April 14, 2021
Exosomes play an important role in metabolic-associated fatty liver disease (MAFLD), but the mechanism by which exosomes participate in MAFLD still remain unclear.
To figure out the function of lipotoxic exosomal miR-1297 in MAFLD.
MicroRNA sequencing was used to detect differentially expressed miRNAs (DE-miR) in lipotoxic exosomes derived from primary hepatocytes. Bioinformatic tools were applied to analyze the target genes and pathways regulated by the DE-miRs. Quantitative real-time PCR (qPCR) was conducted for the verification of DE-miRs. qPCR, western blot, immunofluorescence staining and ethynyl-20-deoxyuridine assay were used to evaluate the function of lipotoxic exosomal miR-1297 on hepatic stellate cells (LX2 cells). A luciferase reporter experiment was performed to confirm the relationship of miR-1297 and its target gene PTEN.
MicroRNA sequencing revealed that there were 61 exosomal DE-miRs (P < 0.05) with a fold-change > 2 from palmitic acid treated primary hepatocytes compared with the vehicle control group. miR-1297 was the most highly upregulated according to the microRNA sequencing. Bioinformatic tools showed a variety of target genes and pathways regulated by these DE-miRs were related to liver fibrosis. miR-1297 was overexpressed in exosomes derived from lipotoxic hepatocytes by qPCR. Fibrosis promoting genes (α-SMA, PCNA) were altered in LX2 cells after miR-1297 overexpression or miR-1297-rich lipotoxic exosome incubation via qPCR and western blot analysis. Immunofluorescence staining and ethynyl-20-deoxyuridine staining demonstrated that the activation and proliferation of LX2 cells were also promoted after the above treatment. PTEN was found to be the target gene of miR-1297 and knocking down PTEN contributed to the activation and proliferation of LX2 cells via modulating the PI3K/AKT signaling pathway.
miR-1297 was overexpressed in exosomes derived from lipotoxic hepatocytes. The lipotoxic hepatocyte-derived exosomal miR-1297 could promote the activation and proliferation of hepatic stellate cells through the PTEN/PI3K/AKT signaling pathway, accelerating the progression of MAFLD.
Core Tip: In this study, the expression of miR-1297 was increased in exosomes derived from primary hepatocytes. Exosomal miR-1297 from lipotoxic LO2 (a hepatocyte cell line) could promote LX2 (a hepatic stellate cell line) activation and proliferation by regulating the PTEN/PI3K/ATK pathway. Currently, the study between exosomes and metabolic-associated fatty liver disease is very limited. This is the first time that exosomal miR-1297 from lipotoxic hepatocytes was confirmed to accelerate liver fibrosis, and the new mechanism may become a promising treatment target for metabolic-associated fatty liver disease.