School of Life Sciences, Beijing University of Chinese Medicine, Beijing, 100029, China.
School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, 100029, China.
Acta Pharmacol Sin. 2023 Dec;44(12):2479-2491. doi: 10.1038/s41401-023-01145-z. Epub 2023 Aug 14.
Liver fibrosis is a wound-healing process characterized by excess formation of extracellular matrix (ECM) from activated hepatic stellate cells (HSCs). Previous studies show that both EZH2, an epigenetic regulator that catalyzes lysine 27 trimethylation on histone 3 (H3K27me3), and long non-coding RNA H19 are highly correlated with fibrogenesis. In the current study, we investigated the underlying mechanisms. Various models of liver fibrosis including Mdr2, bile duct ligation (BDL) and CCl mice were adapted. We found that EZH2 was markedly upregulated and correlated with H19 and fibrotic markers expression in these models. Administration of EZH2 inhibitor 3-DZNeP caused significant protective effects in these models. Furthermore, treatment with 3-DZNeP or GSK126 significantly inhibited primary HSC activation and proliferation in TGF-β-treated HSCs and H19-overexpreesing LX2 cells in vivo. Using RNA-pull down assay combined with RNA immunoprecipitation, we demonstrated that H19 could directly bind to EZH2. Integrated analysis of RNA-sequencing (RNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq) further revealed that H19 regulated the reprogramming of EZH2-mediated H3K27me3 profiles, which epigenetically promoted several pathways favoring HSCs activation and proliferation, including epithelial-mesenchymal transition and Wnt/β-catenin signaling. In conclusion, highly expressed H19 in chronic liver diseases promotes fibrogenesis by reprogramming EZH2-mediated epigenetic regulation of HSCs activation. Targeting the H19-EZH2 interaction may serve as a novel therapeutic approach for liver fibrosis.
肝纤维化是一种以细胞外基质（ECM）过度形成为特征的创伤愈合过程，其由活化的肝星状细胞（HSCs）产生。先前的研究表明，表观遗传调节因子 EZH2 和长链非编码 RNA H19 均与纤维化高度相关，EZH2 催化组蛋白 3（H3）赖氨酸 27 三甲基化（H3K27me3），而 H19 与纤维化标记物的表达呈正相关。在本研究中，我们研究了其潜在机制。我们适应了包括 Mdr2、胆管结扎（BDL）和 CCl4 在内的各种肝纤维化模型。我们发现，这些模型中 EZH2 明显上调，与 H19 和纤维化标记物的表达相关。EZH2 抑制剂 3-DZNeP 的给药在这些模型中产生了显著的保护作用。此外，3-DZNeP 或 GSK126 的治疗显著抑制了 TGF-β处理的 HSCs 和体内过表达 H19 的 LX2 细胞中的原代 HSC 活化和增殖。通过 RNA 下拉测定与 RNA 免疫沉淀相结合，我们证明了 H19 可以直接与 EZH2 结合。RNA 测序（RNA-seq）和染色质免疫沉淀测序（ChIP-seq）的综合分析进一步表明，H19 调节了 EZH2 介导的 H3K27me3 谱的重编程，从而在表观遗传上促进了有利于 HSCs 活化和增殖的几个途径，包括上皮-间充质转化和 Wnt/β-catenin 信号通路。总之，慢性肝病中高表达的 H19 通过重编程 EZH2 介导的 HSCs 活化的表观遗传调控促进纤维化。靶向 H19-EZH2 相互作用可能成为肝纤维化的一种新的治疗方法。
