启动子区H3K27me3修饰异常促使系统性红斑狼疮患者CD4^+T细胞CREMα过表达

Effect of aberrant H3K27me3 modification in promoter regions on c AMP response element modulator α expression in CD4^+T cells from patients with systemic lupus erythematosus

目的探讨SLE中CREMα表达升高的原因。方法分离5名正常对照和5名SLE患者的CD4^+T细胞,用染色质免疫沉淀(ChIP)微阵列法对各种基因启动子区组蛋白H3赖氨酸27三甲基化(H3K27me3)的水平进行分析。随后分离30名正常对照和30名SLE患者的CD4^+T细胞,用ChIP结合实时定量PCR检测CREMα启动子区H3K27me3、H3K27去甲基化酶JMJD3和UTX、H3K27甲基转移酶EZH2的水平,采用实时定量RT-PCR检测CREMαmRNA水平。结果 SLE CD4^+T细胞的CREMα启动子区H3K27me3水平是正常对照的0.23倍。随后通过ChIP结合实时定量PCR,我们证实了SLE患者CD4^+T细胞CREMα启动子区H3K27me3水平显著降低(P<0.001),且与CREMαmRNA水平呈显著负相关(P<0.001)。该区的JMJD3水平显著升高(P<0.001),且与H3K27me3水平呈负相关(P<0.001),与CREMαmRNA水平呈正相关(P<0.001)。而UTX(P=0.172)及EZH2(P=0.281)水平则与对照组无明显差异。结论 SLE CD4^+T细胞CREMα启动子区JMJD3增多,导致该区H3K27me3水平降低,结果促使CREMα过表达,最终引起SLE的发病。

Objective Increased cAMP response element modulator α(CREMα) in T cells plays an essential role in the pathogenesis of systemic lupus erythematosus(SLE).The aim of this study was to investigate the mechanisms that elevates CREMα expression in SLE.Methods CD4^+T cells from 5 healthy volunteers and 5 SLE patients were isolated for analysis of histone H3 lysine 27 trimethylation(H3K27me3) enrichment in different gene promoters using chromatin immunoprecipitation(ChIP) microarray.The levels of H3K27me3,H3 K27 demethylases Jumonji domain containing 3(JMJD3)and ubiquitously transcribed X(UTX),and H3 K27 methyltransferase enhancer of zeste homolog 2(EZH2) within the CREMαpromoter were subsequently tested by ChIP and real-time PCR in CD4^+T cells from 30 normal controls and 30 SLE patients;CREMα mRNA level was also determined by real-time RT-PCR.Results Analysis of ChIP microarray data identified that H3K27me3 enrichment at the CREMα promoter in CD4^+T cells from SLE patients was 0.23 times that of the normal control subjects.The results of ChIP and real-time PCR confirmed a marked decrease of H3K27me3 enrichment at the CREMαpromoter in CD4^+T cells from SLE patients(P<0.001).The level of H3K27me3 at the promoter was negatively correlated with CREMα mRNA level in CD4^+T cells from SLE patients(P<0.001).In addition,a sharp increase was observed in JMJD3 binding at the CREMα promoter region in CD4^+T cells from SLE patients(P<0.001),and it was negatively correlated with H3K27me3 enrichment(P<0.001) and positively correlated with CREMα mRNA level(P<0.001).There were no significant changes in UTX(P=0.172) or EZH2(P=0.281) binding at the CREMα promoter region in CD4^+T cells from SLE patients as compared to normal controls.Conclusion Increased JMJD3 binding down-regulates H3K27me3 enrichment at the CREMα promoter in CD4^+T cells of SLE patients to stimulate CREMα overexpression and result in the development of SLE.