N 6-Methyladenosine modification of circDcbld2 in Kupffer cells promotes hepatic fibrosis via targeting miR-144-3p/Et-1 axis.

Kupffer cells (KCs), as residents and sentinels of the liver, are involved in the formation of hepatic fibrosis (HF). However, the biological functions of circular RNAs (circRNAs) in KCs to HF have not been determined. In this study, the expression levels of circRNAs, microRNAs, and messenger RNAs (mRNAs) in KCs from a mouse model of HF mice were investigated using microarray and circRNA-Seq analyses. circDcbld2 was identified as a candidate circRNA in HF, as evidenced by its up-regulation in KCs. Silver staining and mass spectrometry showed that Wtap and Igf2bp2 bind to cirDcbld2. The suppression of circDcbld2 expression decreased the KC inflammatory response and oxidative stress and inhibited hepatic stellate cell (HSCs) activation, attenuating mouse liver fibrogenesis. Mechanistically, Wtap mediated the N 6-methyladenosine (m6A) methylation of circDcbld2, and Igf2bp2 recognized m6A-modified circDcbld2 and increased its stability. circDcbld2 contributes to the occurrence of HF by binding miR-144-3p/Et-1 to regulate the inflammatory response and oxidative stress. These findings indicate that circDcbld2 functions via the m6A/circDcbld2/miR-144-3p/Et-1 axis and may act as a potential biomarker for HF treatment.