UHRF1 ameliorates liver cirrhosis through suppressing macrophage M1 polarization by catalyzing HMGA2 promoter...

Currently, suppressing macrophage M1 polarization and HSC activation are recognized as potential therapeutic strategies for liver cirrhosis. Ubiquitin-like with PHD and RING Finger Domains 1 (UHRF1) is a crucial epigenetic modulator implicated in maintaining DNA methylation and chromatin structure. Knockdown of high mobility group A protein 2 (HMGA2) was reported to ameliorate hepatic inflammation and fibrosis in nonalcoholic fatty liver disease. Here, the elaborate effect of UHRF1-mediated HMGA2 promoter methylation was investigated during the progression of liver cirrhosis. Transcriptomic sequencing of liver tissues of cirrhotic patients was carried out and a mouse model with liver cirrhosis was established by intraperitoneal injection of carbon tetrachloride (CCl₄) twice weekly for four consecutive weeks. Lipopolysaccharide (LPS)-induced RAW264.7 were transduced with overexpressed UHRF1 adenovirus and cell supernatant was applied as the conditional medium to cultivate hepatic stellate cells (HSCs). Notably, in vivo experiments, enhanced UHRF1 expression alleviated fibrosis and inflammation of mouse livers. In vitro experiments, upregulated UHRF1 suppressed CCl₄-stimulated macrophage M1 polarization and HSC activation. Moreover, MSP assay revealed that methylation was enhanced on HMGA2 promoter at -599/2-450 site after UHRF1 overexpression. More intriguingly, ChIP and Co-IP results clarified that UHRF1 interacted with DNA methyltransferase 1 (DNMT1), thereby bound to HMGA2 promoter and facilitated its methylation. Furthermore, increased HMGA2 level abolished the inhibitory effects of UHRF1 upregulation on the mRNA expression of pro-inflammatory genes of macrophages and genes encoding collagen of HSCs. Collectively, UHRF1 weakened HMGA2 expression by catalyzing its promoter methylation, thereby blocked macrophage M1 polarization and mitigated liver cirrhosis.