Histone H3K27 methyltransferase EZH2 and demethylase JMJD3 regulate hepatic stellate cells activation and liver fibrosis

Abstract

Rationale: As the central hallmark of liver fibrosis, transdifferentiation of hepatic stellate cells (HSCs), the predominant contributor to fibrogenic hepatic myofibroblast responsible for extracellular matrix (ECM) deposition, is characterized with transcriptional and epigenetic remodeling. We aimed to characterize the roles of H3K27 methyltransferase EZH2 and demethylase JMJD3 and identify their effective pathways and novel target genes in HSCs activation and liver fibrosis. Methods: In primary HSCs, we analyzed effects of pharmacological inhibitions and genetic manipulations of EZH2 and JMJD3 on HSCs activation. In HSCs cell lines, we evaluated effects of EZH2 inhibition by DZNep on proliferation, cell cycling, senescence and apoptosis. In CCl 4 and BDL murine models of liver fibrosis, we assessed in vivo effects of DZNep administration and Ezh2 silencing. We profiled rat primary HSCs transcriptomes with RNA-seq, screened the pathways and genes associated with DZNep treatment, analyzed EZH2 and JMJD3 regulation towards target genes by ChIP-qPCR. Results: EZH2 inhibition by DZNep resulted in retarded growth, lowered cell viability, cell cycle arrest in S and G2 phases, strengthened senescence, and enhanced apoptosis of HSCs, decreased hepatic collagen deposition and rescued the elevated serum ALT and AST activities of diseased mice, and downregulated cellular and hepatic expressions of H3K27me3, EZH2, α-SMA and COL1A. Ezh2 silencing by RNA interference in vitro and in vivo showed similar effects. JMJD3 inhibition by GSK-J4 and overexpression of wild-type but not mutant Jmjd3 enhanced or repressed HSCs activation respectively. EZH2 inhibition by DZNep transcriptionally inactivated TGF-β1 pathway, cell cycle pathways and vast ECM components in primary HSCs. EZH2 inhibition decreased H3K27me3 recruitment at target genes encoding TGF-β1 pseudoreceptor BAMBI, anti-inflammatory cytokine IL10 and cell cycle regulators CDKN1A, GADD45A and GADD45B, and increased their expressions, while Jmjd3 overexpression manifested alike effects. Conclusions: EZH2 and JMJD3 antagonistically modulate HSCs activation. The therapeutic effects of DZNep as epigenetic drug in liver fibrosis are associated with the regulation of EZH2 towards direct target genes encoding TGF-β1 pseudoreceptor BAMBI, anti-inflammatory cytokine IL10 and cell cycle regulators CDKN1A, GADD45A and GADD45B, which are also regulated by JMJD3. Our present study provides new mechanistic insight into the epigenetic modulation of EZH2 and JMJD3 in HSCs biology and hepatic fibrogenesis.

Tanshinone I, a new EZH2 inhibitor restricts normal and malignant hematopoiesis through upregulation of MMP9 and ABCG2

“…The Ezh2 -deficient mouse embryos died because of anemia 4 . Methyltransferase EZH2 and demethylase JMJD3 antagonistically modulate HSCs activation by regulation Bambi , Cdkn1a and Gadd45 5 . Overexpression of EZH2 results in the myeloproliferative disorder in mice, and has been shown to be associated with aggressiveness and metastasis of different types of human cancers such as prostate cancer, breast cancer, bladder cancer and melanoma 6 - 10 .…”

Novel Therapeutic Targets in Liver Fibrosis

“…For example, the enhancer of zeste homologue 2 (EZH2), which is responsible for the trimethylation of histone 3 at lysine 27(H3K27me3), is involved in TGF-β dependent fibrogenic pathways (Martin-Mateos et al, 2019). EZH2 and the demethylase JMJD3 regulate HSC activation and liver fibrosis (Jiang et al, 2021). Histone deacetylases 1/2 (HDAC1/2) may regulate liver fibrosis and may therefore be therapeutic targets (Liu et al, 2021;Zhu et al, 2021).…”

“…Several inhibitors of DNA methylation (e.g., 5-azadC, Sennoside A) and histone modifications (e.g., givinostat, DZNep, GSK-503, GSK-J4) as well as epigenetic inhibitors such as CM272 have shown promise for treating liver fibrosis (Yang et al, 2013;Martin-Mateos et al, 2019;Zhu et al, 2020;Barcena-Varela et al, 2021;Ding et al, 2021;Huang et al, 2021;Jiang et al, 2021). Epigenetic biomarkers may be useful not only as treatment targets but also for assaying in tissue and liquid biopsies in order to predict prognosis of patients with liver fibrosis.…”

The Potential Application of Magnetic Nanoparticles for Liver Fibrosis Theranostics

“…In healthy subjects, fresh hepatocytes replenish these spaces. Hepatocytes secrete molecules which act as danger signals for other cell types during the apoptosis process (Jiang et al, 2021). These signals activate immune cells which further release other factors that trigger the apoptosis of liver cells (Figure 1).…”