Zhou Xiaoxu, Zang Xiujuan, Ponnusamy Murugavel, Masucci Monica V, Tolbert Evelyn, Gong Rujun, Zhao Ting C, Liu Na, Bayliss George, Dworkin Lance D, Zhuang Shougang
Department of Medicine, Rhode Island Hospital and Alpert Medical School, Brown University, Providence, Rhode Island; Department of Cardiology, First Affiliated Hospital of Harbin Medical University, Harbin, China;
Department of Medicine, Rhode Island Hospital and Alpert Medical School, Brown University, Providence, Rhode Island; Department of Nephrology, Shanghai Songjiang District Central Hospital, Shanghai, China;
J Am Soc Nephrol. 2016 Jul;27(7):2092-108. doi: 10.1681/ASN.2015040457. Epub 2015 Dec 23.
Enhancer of zeste homolog 2 (EZH2) is a methyltransferase that induces histone H3 lysine 27 trimethylation (H3K27me3) and functions as an oncogenic factor in many cancer types. However, the role of EZH2 in renal fibrogenesis remains unexplored. In this study, we found high expression of EZH2 and H3K27me3 in cultured renal fibroblasts and fibrotic kidneys from mice with unilateral ureteral obstruction and humans with CKD. Pharmacologic inhibition of EZH2 with 3-deazaneplanocin A (3-DZNeP) or GSK126 or siRNA-mediated silencing of EZH2 inhibited serum- and TGFβ1-induced activation of renal interstitial fibroblasts in vitro, and 3-DZNeP administration abrogated deposition of extracellular matrix proteins and expression of α-smooth muscle actin in the obstructed kidney. Injury to the kidney enhanced Smad7 degradation, Smad3 phosphorylation, and TGFβ receptor 1 expression, and 3-DZNeP administration prevented these effects. 3-DZNeP also suppressed phosphorylation of the renal EGF and PDGFβ receptors and downstream signaling molecules signal transducer and activator of transcription 3 and extracellular signal-regulated kinase 1/2 after injury. Moreover, EZH2 inhibition increased the expression of phosphatase and tensin homolog (PTEN), a protein previously associated with dephosphorylation of tyrosine kinase receptors in the injured kidney and serum-stimulated renal interstitial fibroblasts. Finally, blocking PTEN with SF1670 largely diminished the inhibitory effect of 3-DZNeP on renal myofibroblast activation. These results uncovered the important role of EZH2 in mediating the development of renal fibrosis by downregulating expression of Smad7 and PTEN, thus activating profibrotic signaling pathways. Targeted inhibition of EZH2, therefore, could be a novel therapy for treating CKD.
zeste 同源物 2 增强子（EZH2）是一种甲基转移酶，可诱导组蛋白 H3 赖氨酸 27 三甲基化（H3K27me3），并在多种癌症类型中作为致癌因子发挥作用。然而，EZH2 在肾纤维化中的作用仍未得到探索。在本研究中，我们发现 EZH2 和 H3K27me3 在单侧输尿管梗阻小鼠和慢性肾脏病患者的培养肾成纤维细胞和纤维化肾脏中高表达。用 3 - 去氮杂氮胞苷 A（3 - DZNeP）或 GSK126 对 EZH2 进行药理抑制或通过 siRNA 介导沉默 EZH2，在体外抑制了血清和转化生长因子β1（TGFβ1）诱导的肾间质成纤维细胞活化，并且给予 3 - DZNeP 可消除梗阻肾脏中细胞外基质蛋白的沉积和α - 平滑肌肌动蛋白的表达。肾脏损伤增强了 Smad7 的降解、Smad3 的磷酸化以及 TGFβ受体 1 的表达，而给予 3 - DZNeP 可防止这些效应。3 - DZNeP 还抑制了损伤后肾表皮生长因子（EGF）和血小板衍生生长因子β受体（PDGFβ受体）以及下游信号分子信号转导和转录激活因子 3（STAT3）和细胞外信号调节激酶 1/2（ERK1/2）的磷酸化。此外，抑制 EZH2 增加了磷酸酶和张力蛋白同源物（PTEN）的表达，PTEN 是一种先前与损伤肾脏和血清刺激的肾间质成纤维细胞中酪氨酸激酶受体去磷酸化相关的蛋白质。最后，用 SF1670 阻断 PTEN 在很大程度上减弱了 3 - DZNeP 对肾肌成纤维细胞活化的抑制作用。这些结果揭示了 EZH2 通过下调 Smad7 和 PTEN 的表达，从而激活促纤维化信号通路，在介导肾纤维化发展中的重要作用。因此，靶向抑制 EZH2 可能是治疗慢性肾脏病的一种新疗法。
