Altered DNA methylation in leukocytes with trisomy 21.
Altered DNA methylation in leukocytes with trisomy 21.
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DOI：
10.1371/journal.pgen.1001212
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发表时间：
2010-11-18
期刊：
影响因子：
4.5
通讯作者：
Tycko B
中科院分区：
文献类型：
--
作者：
Kerkel K;Schupf N;Hatta K;Pang D;Salas M;Kratz A;Minden M;Murty V;Zigman WB;Mayeux RP;Jenkins EC;Torkamani A;Schork NJ;Silverman W;Croy BA;Tycko B
唐氏综合征（DS）的主要异常是21三体，这是众所周知的;但这种染色体获得如何产生复杂的DS表型，包括免疫系统缺陷，还不清楚。我们分析了DS成人和正常对照的外周血白细胞（PBL）和T淋巴细胞中的DNA甲基化，发现DS中CpG甲基化的基因特异性异常，许多差异甲基化的基因在淋巴细胞发育和功能中具有已知或预测的作用。通过亚硫酸氢盐测序和甲基化敏感的焦磷酸测序（MS-Pyroseq）对微阵列数据的验证证实了DS与对照PBL中测试的8个基因中的每一个的甲基化的强烈差异（p<0.0001）：TMEM 131、TCF 7、CD 3 Z/CD 247、SH 3BP 2、EIF 4 E、PLD 6、SUMO 3和CPT 1B。此外，我们通过亚硫酸氢盐测序验证了DS与对照T细胞中NOD 2/CARD 15的差异甲基化。差异甲基化的基因被发现在各种常染色体上，21号染色体上没有富集。甲基化的差异在给定个体中通常是稳定的，在调整年龄后仍然显着，并且不是由于细胞计数的改变。在DS和对照PBL中，部分（但不是全部）差异甲基化基因显示出不同的平均mRNA表达;通过将正常淋巴细胞暴露于去甲基化药物5-氮杂-2 ′脱氧胞苷（5aza-dC）和促分裂剂，重现了其中5个基因（TMEM 131、TCF 7、CD 3 Z、NOD 2和NPDC 1）表达的改变。我们的结论是，改变基因特异性DNA甲基化是一个经常性的和功能相关的下游反应，在人类细胞中的21三体。唐氏综合征（DS; 21三体）是由一个额外的21号染色体的增益。然而，这条额外染色体产生DS中出现的医学异常的机制仍然不清楚，这些异常不仅包括智力低下，还包括对自身免疫性疾病和复发性感染的易感性。DNA甲基化是可能导致这些异常的机制。为了检验这种可能性，我们分析了DS成人和正常对照组的白色血细胞中的DNA甲基化，发现了DS中基因甲基化的复发性异常，其中几个差异甲基化基因在血细胞中起作用。与来自正常成人的相同类型细胞相比，来自DS成人的白色血细胞或纯化T淋巴细胞中具有低甲基化或高甲基化的基因包括TMEM 131、TCF 7、CD 3 Z、SH 3BP 2、EIF 4 E、SUMO 3、CPT 1B、NOD 2/CARD 15、NPDC 1和PLD 6。其中几个基因不仅表现出不同的甲基化，而且在DS与对照血细胞中表现出不同的表达，这通过将正常白色血细胞暴露于去甲基化药物来概括。这些发现表明，特定基因组的DNA甲基化改变是人类获得额外21号染色体的基本细胞反应。这里发现的异常甲基化基因可能导致DS患者免疫系统异常。
The primary abnormality in Down syndrome (DS), trisomy 21, is well known; but how this chromosomal gain produces the complex DS phenotype, including immune system defects, is not well understood. We profiled DNA methylation in total peripheral blood leukocytes (PBL) and T-lymphocytes from adults with DS and normal controls and found gene-specific abnormalities of CpG methylation in DS, with many of the differentially methylated genes having known or predicted roles in lymphocyte development and function. Validation of the microarray data by bisulfite sequencing and methylation-sensitive Pyrosequencing (MS-Pyroseq) confirmed strong differences in methylation (p<0.0001) for each of 8 genes tested: TMEM131, TCF7, CD3Z/CD247, SH3BP2, EIF4E, PLD6, SUMO3, and CPT1B, in DS versus control PBL. In addition, we validated differential methylation of NOD2/CARD15 by bisulfite sequencing in DS versus control T-cells. The differentially methylated genes were found on various autosomes, with no enrichment on chromosome 21. Differences in methylation were generally stable in a given individual, remained significant after adjusting for age, and were not due to altered cell counts. Some but not all of the differentially methylated genes showed different mean mRNA expression in DS versus control PBL; and the altered expression of 5 of these genes, TMEM131, TCF7, CD3Z, NOD2, and NPDC1, was recapitulated by exposing normal lymphocytes to the demethylating drug 5-aza-2′deoxycytidine (5aza-dC) plus mitogens. We conclude that altered gene-specific DNA methylation is a recurrent and functionally relevant downstream response to trisomy 21 in human cells. Down syndrome (DS; trisomy 21) is caused by the gain of a single extra chromosome 21. However, the mechanisms by which this extra chromosome produces the medical abnormalities seen in DS, including not only mental retardation but also susceptibility to autoimmune diseases and recurrent infections, are still not understood. DNA methylation is a mechanism that might contribute to these abnormalities. To test this possibility, we profiled DNA methylation in white blood cells from adults with DS and normal controls and found recurrent abnormalities of gene methylation in DS, with several of the differentially methylated genes having roles in blood cells. Among the genes with hypo- or hyper-methylation in white blood cells or purified T-lymphocytes from adults with DS, compared to these same types of cells from normal adults, were TMEM131, TCF7, CD3Z, SH3BP2, EIF4E, SUMO3, CPT1B, NOD2/CARD15, NPDC1, and PLD6. Several of these genes showed not only different methylation but also different expression in DS versus control blood cells, which was recapitulated by exposing normal white blood cells to a demethylating drug. These findings show that altered DNA methylation of a specific group of genes is a fundamental cellular response to the gain of an extra chromosome 21 in humans. The abnormally methylated genes identified here may contribute to immune system abnormalities in people with DS.
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30.8
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