Hepatology International最新文献

Background and aims: Liver fibrosis, a wound-healing response to chronic injury, can progress to cirrhosis and hepatocellular carcinoma. We investigated Tripartite motif-containing protein 26 (TRIM26) in liver fibrosis and its mechanisms.

Methods: TRIM26 knockout (Trim26⁻^/⁻) mice were generated to study Trim26's role in liver fibrosis. Histological analyses, qPCR, and western blotting were conducted to examine fibrosis markers and macrophage activation. In vitro studies examined macrophage polarization and hepatic stellate cells (HSCs) activation. Co-immunoprecipitation and ubiquitination assays were performed to explore the interaction between TRIM26 and enhancer of zeste homolog 2 (EZH2).

Results: TRIM26 expression was significantly downregulated in human cirrhotic tissues and fibrotic mouse livers. In Trim26^⁻/⁻ mice, CCl₄- and BDL-induced fibrosis models exhibited exacerbated collagen deposition, elevated α-smooth muscle actin (α-SMA), and type I collagen (Collagen I) expression, whereas AAV-mediated Trim26 restoration markedly ameliorated these pathological features. Transcriptomic and cellular analyses indicated that Trim26 deficiency increased the pro-inflammatory cytokines, activated NF-κB and STAT1 signaling pathways, enhanced M1 macrophage polarization, and increased inflammatory cell infiltration. In vitro experiments confirmed that conditioned medium from Trim26-deficient macrophages significantly promoted α-SMA and collagen expression in HSCs. Mechanistically, TRIM26 interacts with EZH2, inhibiting TRAF6-mediated K48-linked ubiquitination and degradation to maintain EZH2 stability. EZH2, in turn, suppresses STAT1 transcriptional activity by catalyzing H3K27me3 modification on the STAT1 gene chromatin. EZH2 degradation leads to STAT1 upregulation, exacerbating M1 macrophage polarization.

Conclusion: Trim26 attenuates liver fibrosis by stabilizing EZH2 and regulating macrophage polarization, which reduces HSC activation.

Background: Liver fibrosis is characterized by deposition of excessive extracellular matrix (ECM). The major source of ECM is activated hepatic stellate cells (HSCs). NAT10 is the only known acetyltransferase catalyzing ac4C RNA modification. The purpose of this study is to explore the role of NAT10 acting as ac4C acetyltransferase during HSC activation.

Methods: NAT10 was detected in fibrotic liver tissues from S. japonicum infected mice with immunohistochemistry and TGF-β1 stimulated LX-2 human HSC cells with Western blot and immunofluorescent staining. NAT10 was inhibited with specific siRNA in LX-2 cells to detect HSC activation molecular marker with Western blot, cell motility with Transwell assay, cell proliferation with CCK8 assay. ac4C modification was assessed in TGF-β1 stimulated LX-2 cells with immunofluorescent staining. ac4C chemical sequencing and transcriptomic sequencing analysis were performed to analyze ac4C modified genes regulated by NAT10 in TGF-β1 stimulated LX-2 cells. Possible target genes regulated by NAT10 were determined using qPCR, RIP-qPCR, RNA stability assay, and were further verified using primary hepatic stellate cells from mice and using analysis of GEO datasets.

Results: NAT10 increases in S. japonicum infected mice liver and activated HSCs. NAT10 inhibition suppresses HSC activation. NAT10 is correlated with TGFB1 and COL1A1 expression in activated HSCs. NAT10 promotes the ac4C modification and stability of TGFB1 and COL1A1 mRNA, thus enhancing their protein expression.

Conclusions: NAT10 functions as an ac4C acetyltransferase and forms a positive feedback with TGF-β1 in HSCs, thereby modulating the TGF-β1-ac4C-COL1A1 axis, to promote HSC activation and liver fibrosis progression.