Epigenetic modifications associated with intrauterine exposure to maternal type 2 diabetes.

在子宫内暴露于母体糖尿病的个体更有可能在以后的生活中发展代谢和心血管疾病。这可能部分归因于基因表达的表观遗传调控。为了检查是否可以在妊娠期间患有2型糖尿病（OMD）的母亲的后代中观察到差异DNA甲基化，表观遗传调节的主要来源，与妊娠期间没有2型糖尿病（OMND）的母亲的后代相比，我们进行了表观基因组关联研究。在388名美洲原住民中，共分析了423，311个胞嘧啶磷酸鸟嘌呤（CpG）位点，其中187个为OMD，201个为OMND。48个差异甲基化的CpG位点（经验错误发现率<0.05），映射到29个基因和10个基因间区域，被确定。具有最强证据的基因是LHX3，其中6个CpG位点在OMD中高度甲基化（P 1.1 10 - 5）。类似地，PRDM16附近的CpG在OMD中高度甲基化（高1.1%，P = 5.6 10 - 7），其中高度甲基化也预测未来的糖尿病风险（风险比= 2.12，P = 9.7 10 - 5）。AK3L1附近的高甲基化和PCDHGA 4和STC 1的低甲基化与子宫内糖尿病暴露和葡萄糖耐量正常的后代中胰岛素分泌功能降低相关。对所有29个基因的总体分析未显示任何生物学途径的富集;然而，文献检索提供了证据，证明其中几个基因在胚胎发育和/或β细胞功能中发挥作用。我们得出结论，宫内暴露于糖尿病可以影响多个基因组位点的甲基化。其中一些位点的甲基化状态会损害胰岛素分泌，增加体重并增加2型糖尿病的风险。 我们还进行了全基因组分析，以确定甲基化与皮马印第安人BMI相关的CpG位点。在Illumina Infinium HumanMethylation 450 BeadChip上测量了399份外周血白细胞样本的DNA甲基化，并分析了423，311个CpG位点。对每个受试者的BMI（在血液采样时测量）进行自然对数转换，并测试其与DNA甲基化的相关性，并对适当的协变量进行调整。在发现队列（FDR p 0.05）中实现全基因组显著性的CpG位点在皮马印第安人的两个现有数据集中进行了复制分析（N = 320，年龄= 35; N = 183，年龄= 53）。在发现队列中与BMI相关的263个CpG位点中，9个在两个复制队列中复制（p 0.05且作用方向一致）。它们分别位于6个基因和2个增强子元件上。这些CpG位点中的三个定位于基因（AHRR、RPS6KA2和LGALS3BP），其中DNA甲基化先前已被报道与其他人群中的BMI相关。其余基因（DUSP5，RRAS2，APOBR）和增强子元件的表观遗传关联是新的。这些基因中的几个在炎症（DUSP5、LGALS3BP、APOBR、RPS6KA2）或细胞增殖（RRAS2和AHRR）中具有已知的作用。因此，本研究证实了某些基因的DNA甲基化与不同种族的肥胖有关，并确定了其他可能在美洲印第安人中产生更大影响的基因。

Individuals exposed to maternal diabetes in utero are more likely to develop metabolic and cardiovascular diseases later in life. This may be partially attributable to epigenetic regulation of gene expression. To examine whether differential DNA methylation, a major source of epigenetic regulation, can be observed in offspring of mothers with type 2 diabetes (OMD) during the pregnancy as compared to offspring of mothers with no type 2 diabetes(OMND) during the pregnancy, we performed an epigenome-wide association study. A total of 423,311 cytosine-phosphate-guanine (CpG) sites were analyzed in 388 Native Americans, of which 187 were OMD and 201 were OMND. Forty-eight differentially methylated CpG sites (with empirical false discovery rate < 0.05), mapping to 29 genes and 10 intergenic regions, were identified. The gene with the strongest evidence was LHX3, where 6 CpG sites were hyper-methylated in OMD (P 1.1 10-5). Similarly, a CpG near PRDM16 was hyper-methylated in OMD (1.1% higher, P = 5.6 10-7), where hyper-methylation also predicted future diabetes risk (hazard ratio = 2.12, P = 9.7 10-5). Hyper-methylation near AK3L1 and hypo-methylation at PCDHGA4 and STC1 associated with exposure to diabetes in utero and decreased insulin secretory function among offspring with normal glucose tolerance. Analysis of all 29 genes in aggregate did not shown enrichment for any biologic pathway; however, literature searches provided evidences that several of these genes have a role in embryonic development and/or beta cell function. We conclude that intrauterine exposure to diabetes can affect methylation at multiple genomic sites. Methylation status at some of these sites can impair insulin secretion, increase body weight and increase risk of type 2 diabetes. We have also conducted a genome-wide analysis to identify CpG sites at which methylation associates with BMI in Pima Indians. DNA methylation in 399 peripheral blood leukocyte samples was measured on the Illumina Infinium HumanMethylation450 BeadChip, and 423,311 CpG sites were analyzed. Each subject's BMI (measured at the time of blood sampling) was natural logarithm transformed and tested for association with DNA methylation with adjustments for appropriate covariates. CpG sites that achieved genome-wide significance in the discovery cohort (FDR p 0.05) were analyzed for replication in two existing datasets of Pima Indians (N = 320, age = 35; N = 183, age = 53). Among 263 CpG sites that associated with BMI in the discovery cohort, 9 replicated (p 0.05 and consistent direction of effect) in both replication cohorts. These were located in 6 genes and 2 enhancer elements. Three of these CpG sites map to genes (AHRR, RPS6KA2 and LGALS3BP) where DNA methylation has previously been reported to associate with BMI in other populations. The epigenetic associations at the remaining genes (DUSP5, RRAS2, APOBR) and enhancer elements are novel. Several of these genes have known roles in inflammation (DUSP5, LGALS3BP, APOBR, RPS6KA2) or cell proliferation (RRAS2 and AHRR). Thus, the present study has validated that DNA methylation at some genes associates with obesity in different ethnic groups, and it identifies other genes that may have a larger effect in American Indians.