Department of Surgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, No. 123, Dapi Rd., Niaosong Dist., Kaohsiung, 833, Taiwan.
J Gastroenterol. 2014 Aug;49(8):1285-97. doi: 10.1007/s00535-013-0892-0. Epub 2013 Oct 6.
Multiple mechanisms contribute to the liver fibrosis following cholestasis. Recent research has focused on the role of transforming growth factor β-1 (TGF-β1) in the progression of fibrosis. The aim of our study is to examine the role of epigenetic chromatin marks, such as histone H3 lysine methylation (H3Kme), in bile duct ligation (BDL)-induced TGF-β1 gene expression in rat liver.
Time course of methylated-histone H3 and SET7/9 recruitment were determined by chromatin immunoprecipitation in livers from BDL rats on days 1, 4, 9 and 14. Levels of TGF-β1 and SET7/9 were determined by western blots. The effect of SET7/9 knockdown on BDL-induced expression of TGF-β1, serum enzymes and liver collagen content was studied in vivo.
Results showed that BDL increased the expression of the TGF β-1. Increased levels of active chromatin marks (H3K4me1, H3K4me2, and H3K4me3) and decreased levels of repressive marks (H3K9me2 and H3K9me3) in TGF-β1 promoter accompanied the changes in expression of the TGF β-1. BDL also increased expression of the H3K4 methyltransferase SET7/9 and recruitment to the promoter. SET7/9 gene knockdown with siRNAs significantly attenuated BDL-induced TGF-β1 gene expression, serum enzymes and liver collagen content.
Taken together, these results show the functional role of epigenetic chromatin histone H3Kme in BDL-induced TGF-β1 expression. Pharmacologic and other therapies that reverse these modifications could have potential hepatoprotective effects for BDL-induced cirrhosis.
多种机制导致胆汁淤积后的肝纤维化。最近的研究集中在转化生长因子β-1（TGF-β1）在纤维化进展中的作用。我们的研究目的是研究表观遗传染色质标记，如组蛋白 H3 赖氨酸甲基化（H3Kme），在胆管结扎（BDL）诱导的大鼠肝 TGF-β1 基因表达中的作用。
通过 BDL 大鼠肝脏中的染色质免疫沉淀，确定第 1、4、9 和 14 天甲基化组蛋白 H3 和 SET7/9 募集的时间过程。通过 Western blot 测定 TGF-β1 和 SET7/9 的水平。体内研究了 SET7/9 敲低对 BDL 诱导的 TGF-β1、血清酶和肝胶原含量表达的影响。
结果表明，BDL 增加了 TGF-β1 的表达。TGF-β1 启动子中活性染色质标记（H3K4me1、H3K4me2 和 H3K4me3）水平升高和抑制性标记（H3K9me2 和 H3K9me3）水平降低伴随着 TGF-β1 的表达变化。BDL 还增加了 H3K4 甲基转移酶 SET7/9 的表达并募集到启动子。用 siRNAs 进行 SET7/9 基因敲低显着减弱了 BDL 诱导的 TGF-β1 基因表达、血清酶和肝胶原含量。
综上所述，这些结果表明表观遗传染色质组蛋白 H3Kme 在 BDL 诱导的 TGF-β1 表达中的功能作用。逆转这些修饰的药理学和其他疗法可能对 BDL 诱导的肝硬化具有潜在的肝保护作用。
