Myc-mediated circular RNA circMcph1/miR-370-3p/Irak2 axis is a progressive regulator in hepatic fibrosis.

Aims: Treating hepatic fibrosis (HF) is a major challenge worldwide. However, the biological functions and regulatory mechanisms of circular RNAs (circRNAs) remain unclear in HF. The present study aimed to elucidate the novel role of circMcph1 in HF.

Main Methods: HF mouse model was established by injecting CCl intraperitoneally and validated using hematoxylin and eosin staining, immunohistochemistry, and serological tests in vivo. RAW264.7 cells were treated with lipopolysaccharide (LPS) and interferon-γ (IFN-γ) in vitro inflammatory damage model. Gel electrophoresis, DNA sequencing, RNase R and actinomycin D treatment, random 6 primers and oligo dT primers assay, nuclear and cytoplasmic fractionation assay, and fluorescence in situ hybridization were performed to identify the characteristics of circMcph1. Functional assays such as ELISA, flow cytometry, and adeno-associated virus administration in vivo and liposome delivery gene therapy in vitro were used to determine the functional effects of circMcph1/miR-370-3p/interleukin-1 receptor-associated kinase 2 (Irak2) axis. Mechanistic assays such as luciferase reporter analysis, and chromatin immunoprecipitation revealed the molecular mechanism of the Myc/circMcph1/miR-370-3p/Irak2 axis in HF.

Key Findings: CircMcph1 expression was upregulated in liver tissues and primary Kupffer cells of CCl-induced HF mice, as well as in LPS and IFN-γ-treated RAW264.7 cells. Knockdown of circMcph1 ameliorated liver fibrogenesis and inflammatory damage in HF mice and reduced the inflammatory response in LPS and IFN-γ-treated RAW264.7 cells. Mechanically, circMcph1 mediated by Myc regulated the expression of Irak2 by sponging miR-370-3p in HF.

Significance: The study findings suggested that the Myc/circMcph1/miR-370-3p/Irak2 axis might be a novel identifier and therapeutic target for HF.