The Second Clinical Medical College, Jinan University, Guangdong, China.
Clin Exp Rheumatol. 2010 Mar-Apr;28(2):158-68. Epub 2010 May 13.
Histone H3 lysine 4 trimethylation(H3K4me3) is an important epigenetic modification and associated with active transcription in multiple organisms. In systemic lupus erythematosus (SLE), global and gene-specific DNA methylation changes have been demonstrated to occur. However, to date, our knowledge about the alterations in the histone lysine methylation in SLE is known little. This study aimed to investigate the variations in H3K4me3 in CpG island regions in the peripheral blood mononuclear cells (PBMCs) of SLE patients and the controls, including rheumatoid arthritis patients and healthy subjects.
PBMCs were isolated by density gradient centrifugation from 10 active SLE patients, 7 inactive SLE patients, 8 rheumatoid arthritis patients and 8 healthy volunteers. H3K4me3 variations were analysed by using chromatin immunoprecipitation linked to the microarray (ChIP-chip) approach. ChIP-real time PCR was used to validate the microrray results. Expression analysis by qRT-PCR revealed correlations between mRNA and H3K4me3 levels. In addition, DNA methylation status was also further analysed by Methyl-DNA immunoprecipitation-quantitative PCR.
Many key relevant candidate genes (such as PTPN22, LRP1B etc.) displaying differential changes in H3K4me3 in SLE versus controls (rheumatoid arthritis patients, healthy subjects) were identified. The results of ChIP-real time PCR were coincided well with those of microarray. Aberrant DNA methylation can also be found on selected randomly positive genes (WDR5, SLC24A3, PTPN22, LRP1B METT10D and CDH13).
Our results first indicate that there are significant alterations of H3K4me3 in PBMCs of SLE patients, and H3K4me3 alterations are associated with the pathogenesis of the SLE. Such novel findings show the significance of H3K4me3 as a potential biomarker or promising target for epigenetic-based lupus therapies.
组蛋白 H3 赖氨酸 4 三甲基化（H3K4me3）是一种重要的表观遗传修饰，与多种生物的活跃转录有关。在系统性红斑狼疮（SLE）中，已经证明存在全基因组和基因特异性的 DNA 甲基化变化。然而，迄今为止，我们对 SLE 中组蛋白赖氨酸甲基化的改变知之甚少。本研究旨在研究 SLE 患者和对照组（包括类风湿关节炎患者和健康受试者）外周血单个核细胞（PBMC）中 CpG 岛区域的 H3K4me3 变化。
通过密度梯度离心法从 10 例活动期 SLE 患者、7 例非活动期 SLE 患者、8 例类风湿关节炎患者和 8 例健康志愿者中分离 PBMC。采用染色质免疫沉淀结合微阵列（ChIP-chip）方法分析 H3K4me3 变化。ChIP 实时 PCR 用于验证微阵列结果。qRT-PCR 表达分析显示 mRNA 和 H3K4me3 水平之间存在相关性。此外，还通过甲基化 DNA 免疫沉淀-定量 PCR 进一步分析 DNA 甲基化状态。
确定了许多关键的候选基因（如 PTPN22、LRP1B 等）在 SLE 与对照组（类风湿关节炎患者、健康受试者）之间的 H3K4me3 变化存在差异。ChIP 实时 PCR 的结果与微阵列的结果吻合良好。在随机选择的阳性基因（WDR5、SLC24A3、PTPN22、LRP1B、METT10D 和 CDH13）上也可以发现异常的 DNA 甲基化。
我们的研究结果首次表明，SLE 患者 PBMC 中存在 H3K4me3 的显著改变，H3K4me3 的改变与 SLE 的发病机制有关。这些新发现表明 H3K4me3 作为一种潜在的生物标志物或有希望的表观遗传治疗狼疮的靶点具有重要意义。
