Kok Dieuwertje E G, Dhonukshe-Rutten Rosalie A M, Lute Carolien, Heil Sandra G, Uitterlinden André G, van der Velde Nathalie, van Meurs Joyce B J, van Schoor Natasja M, Hooiveld Guido J E J, de Groot Lisette C P G M, Kampman Ellen, Steegenga Wilma T
Division of Human Nutrition, Wageningen University, PO Box 8129, 6700 EV Wageningen, The Netherlands.
Department of Clinical Chemistry, Erasmus University Medical Center, Rotterdam, The Netherlands.
Clin Epigenetics. 2015 Nov 14;7:121. doi: 10.1186/s13148-015-0154-5. eCollection 2015.
Folate and its synthetic form folic acid function as donor of one-carbon units and have been, together with other B-vitamins, implicated in programming of epigenetic processes such as DNA methylation during early development. To what extent regulation of DNA methylation can be altered via B-vitamins later in life, and how this relates to health and disease, is not exactly known. The aim of this study was to identify effects of long-term supplementation with folic acid and vitamin B12 on genome-wide DNA methylation in elderly subjects. This project was part of a randomized, placebo-controlled trial on effects of supplemental intake of folic acid and vitamin B12 on bone fracture incidence (B-vitamins for the PRevention Of Osteoporotic Fractures (B-PROOF) study). Participants with mildly elevated homocysteine levels, aged 65-75 years, were randomly assigned to take 400 μg folic acid and 500 μg vitamin B12 per day or a placebo during an intervention period of 2 years. DNA was isolated from buffy coats, collected before and after intervention, and genome-wide DNA methylation was determined in 87 participants (n = 44 folic acid/vitamin B12, n = 43 placebo) using the Infinium HumanMethylation450 BeadChip.
After intervention with folic acid and vitamin B12, 162 (versus 14 in the placebo group) of the 431,312 positions were differentially methylated as compared to baseline. Comparisons of the DNA methylation changes in the participants receiving folic acid and vitamin B12 versus placebo revealed one single differentially methylated position (cg19380919) with a borderline statistical significance. However, based on the analyses of differentially methylated regions (DMRs) consisting of multiple positions, we identified 6 regions that differed statistically significantly between the intervention and placebo group. Pronounced changes were found for regions in the DIRAS3, ARMC8, and NODAL genes, implicated in carcinogenesis and early embryonic development. Furthermore, serum levels of folate and vitamin B12 or plasma homocysteine were related to DNA methylation of 173, 425, and 11 regions, respectively. Interestingly, for several members of the developmental HOX genes, DNA methylation was related to serum levels of folate.
Long-term supplementation with folic acid and vitamin B12 in elderly subjects resulted in effects on DNA methylation of several genes, among which genes implicated in developmental processes.
叶酸及其合成形式叶酸作为一碳单位的供体，与其他B族维生素一起，参与早期发育过程中诸如DNA甲基化等表观遗传过程的编程。在生命后期，B族维生素能在多大程度上改变DNA甲基化的调控，以及这与健康和疾病有何关系，目前尚不完全清楚。本研究的目的是确定长期补充叶酸和维生素B12对老年受试者全基因组DNA甲基化的影响。该项目是一项关于补充叶酸和维生素B12对骨折发生率影响的随机、安慰剂对照试验的一部分（预防骨质疏松性骨折的B族维生素（B-PROOF）研究）。同型半胱氨酸水平轻度升高、年龄在65 - 75岁的参与者被随机分配，在2年的干预期内每天服用400μg叶酸和500μg维生素B12或安慰剂。从干预前后采集的血沉棕黄层中分离DNA，并使用Infinium HumanMethylation450 BeadChip对87名参与者（n = 44叶酸/维生素B12组，n = 43安慰剂组）进行全基因组DNA甲基化检测。
叶酸和维生素B12干预后，431,312个位点中有162个（安慰剂组为14个）与基线相比存在差异甲基化。接受叶酸和维生素B12的参与者与安慰剂组的DNA甲基化变化比较显示，有一个单一的差异甲基化位点（cg19380919）具有边缘统计学意义。然而，基于对由多个位点组成的差异甲基化区域（DMR）的分析，我们确定了干预组和安慰剂组之间有6个区域存在统计学显著差异。在DIRAS3、ARMC8和NODAL基因的区域发现了明显变化，这些基因与致癌作用和早期胚胎发育有关。此外，血清叶酸和维生素B12水平或血浆同型半胱氨酸分别与173个、425个和11个区域的DNA甲基化有关。有趣的是，对于发育HOX基因的几个成员，DNA甲基化与血清叶酸水平有关。
老年受试者长期补充叶酸和维生素B12会对多个基因的DNA甲基化产生影响，其中包括与发育过程相关的基因。
