Center of Experimental Rheumatology, University Hospital Zurich and Zurich Center of Integrative Human Physiology, Zurich, Switzerland.
Ann Rheum Dis. 2011 Aug;70(8):1482-8. doi: 10.1136/ard.2010.143040. Epub 2011 Apr 22.
To study the expression, regulation and function of the histone methyltransferase enhancer of zeste homologue 2 (EZH2) in synovial fibroblasts (SF) from patients with rheumatoid arthritis (RA) and osteoarthritis (OA).
SF were obtained from RA and OA patients undergoing joint surgery. Expression levels were assessed by quantitative real-time PCR and western blot. Kinase inhibitors and reporter gene assays were employed to study signalling pathways. Functional analyses included EZH2 overexpression by plasmid transfection and gene silencing by small interfering RNA. Chromatin immunoprecipitation assay was used to analyse histone methylation within distinct promoter regions.
By studying the expression and function of EZH2 in SF the authors found that EZH2 is overexpressed in rheumatoid arthritis synovial fibroblasts (RASF) and further induced by tumour necrosis factor alpha through the nuclear factor kappa B and Jun kinase pathways. As a target gene of EZH2 the authors identified secreted frizzled-related protein 1 (SFRP1), an inhibitor of Wnt signalling, which is associated with the activation of RASF, and show that SFRP1 expression correlates with the occupation of its promoter with activating and silencing histone marks.
These data strongly suggest that the chronic inflammatory environment of the RA joint induces EZH2 and thus might cause changes in the epigenetic programmes of SF.
研究组蛋白甲基转移酶增强子的锌指蛋白 2（EZH2）在类风湿关节炎（RA）和骨关节炎（OA）患者滑膜成纤维细胞（SF）中的表达、调控和功能。
从接受关节手术的 RA 和 OA 患者中获取 SF。通过定量实时 PCR 和 Western blot 评估表达水平。采用激酶抑制剂和报告基因检测研究信号通路。功能分析包括通过质粒转染过表达 EZH2 和通过小干扰 RNA 基因沉默。染色质免疫沉淀分析用于分析不同启动子区域内的组蛋白甲基化。
通过研究 SF 中 EZH2 的表达和功能，作者发现 EZH2 在类风湿关节炎滑膜成纤维细胞（RASF）中过度表达，并通过核因子 kappa B 和 Jun 激酶途径进一步被肿瘤坏死因子-α诱导。作为 EZH2 的靶基因，作者鉴定出分泌卷曲相关蛋白 1（SFRP1），它是 Wnt 信号通路的抑制剂，与 RASF 的激活有关，并表明 SFRP1 的表达与它的启动子被激活和沉默的组蛋白标记占据有关。
这些数据强烈表明，RA 关节的慢性炎症环境诱导了 EZH2，从而可能导致 SF 中表观遗传程序的改变。
