Aim: To investigate the effect of B12 and/or folic acid supplementation on genome-wide DNA methylation. Methods: We performed Infinium HumanMethylation450 BeadChip (Zymo Research, CA, USA) assay in children supplemented with B12 and/or folic acid (n = 12 in each group) and investigated the functional mechanism of selected differentially methylated loci. Results: We noted significant methylation changes postsupplementation in B12 (589 differentially methylated CpGs and 2892 regions) and B12 + folic acid (169 differentially methylated CpGs and 3241 regions) groups. Type 2 diabetes-associated genes TCF7L2 and FTO; and a miRNA, miR21 were further investigated in another B12-supplementation cohort. We also demonstrate that methylation influences miR21 expression and FTO, TCF7L2, CREBBP/CBP and SIRT1 are direct targets of miR21-3p. Conclusion: B12 supplementation influences regulation of several metabolically important Type 2 diabetes-associated genes through methylation of miR21. Hence, our study provides nove...

Mounting evidence suggests that nutritional exposures during pregnancy influence the fetal epigenome, and that these epigenetic changes can persist postnatally, with implications for disease risk across the life course. We review human intergenerational studies using a three-part search strategy. Search 1 investigates associations between preconceptional or pregnancy nutritional exposures, focusing on one-carbon metabolism, and offspring DNA methylation. Search 2 considers associations between offspring DNA methylation at genes found in the first search and growth-related, cardiometabolic and cognitive outcomes. Search 3 isolates those studies explicitly linking maternal nutritional exposure to offspring phenotype via DNA methylation. Finally, we compile all candidate genes and regions of interest identified in the searches and describe their genomic locations, annotations and coverage on the Illumina Infinium Methylation beadchip arrays. We summarize findings from the 34 studies found in the first search, the 31 studies found in the second search and the eight studies found in the third search. We provide details of all regions of interest within 45 genes captured by this review. Many studies have investigated imprinted genes as priority loci, but with the adoption of microarray-based platforms other candidate genes and gene classes are now emerging. Despite a wealth of information, the current literature is characterized by heterogeneous exposures and outcomes, and mostly comprise observational associations that are frequently underpowered. The synthesis of current knowledge provided by this review identifies research needs on the pathway to developing possible early life interventions to optimize lifelong health.

S-adenosylmethionine (SAM) is a donor which provides the methyl groups for histone or nucleic acid modification and phosphatidylcholine production. SAM is hypothesized to link metabolism and chromatin modification, however, its role in acute gene regulation is poorly understood. We recently found that Caenorhabditis elegans with reduced SAM had deficiencies in H3K4 trimethylation (H3K4me3) at pathogen-response genes, decreasing their expression and limiting pathogen resistance. We hypothesized that SAM may be generally required for stress-responsive transcription. Here, using genetic assays, we show that transcriptional responses to bacterial or xenotoxic stress fail in C. elegans with low SAM, but that expression of heat shock genes are unaffected. We also found that two H3K4 methyltransferases, set-2/SET1 and set-16/MLL, had differential responses to survival during stress. set-2/SET1 is specifically required in bacterial responses, whereas set-16/MLL is universally required. These results define a role for SAM in the acute stress-responsive gene expression. Finally, we find that modification of metabolic gene expression correlates with enhanced survival during stress. Animals respond to stress by activating suites of protective genes. A specific metabolite, S-adenosylmethionine (SAM), influences how these genes are activated in a variety of stress conditions. SAM is produced by the 1-carbon cycle and is the major donor for methylation reactions. Thus, SAM is used in the modification of histones, DNA, RNA and production of phospholipids. Here, we show that C. elegans with low SAM have reduced responses to a bacterial and toxic stress, but respond normally to heat stress. We also analyzed how animals that have reduced activity in some of the enzymes that use SAM to modify histones might respond to stress. One enzyme, SET-2, was needed only for survival in bacterial stress, whereas the other related enzyme, SET-16, was universally required. The availability of SAM may be affected by diets low in choline or methionine, alcohol or diseases such as cystic fibrosis. Thus, low SAM availability may leave organisms less able to respond to additional stress, which could exacerbate tissue injury or disease progression.

Aim: Altered maternal one-carbon metabolism influences placental DNA methylation patterns and ‘programs’ the fetus for noncommunicable diseases in adult life. Experimental procedures: Levels of plasma folate, vitamin B12, homocysteine, mRNA and protein levels of MTHFR and MTR enzymes in placenta were compared among women delivering preterm (n = 83) and term (n = 75). MTR promoter CpG methylation was undertaken. Results: MTHFR and MTR mRNA levels were higher while protein levels were lower, and MTR CpG sites were hypermethylated in the preterm group, as compared with the term group. Methylated CpG sites were negatively associated with maternal plasma vitamin B12 levels. Conclusion: Study suggests a dysregulation of enzyme genes in remethylation arm of the one-carbon metabolism in placenta of women delivering preterm.

Identification and functional characterization of cis-regulatory elements in human PPARD gene. We used various bioinformatic tools on the publicly available human genome and Encyclopedia of DNA Elements databases to explore potential cis-regulatory elements in PPARD gene region. We predicted an insulator and an enhancer element in intron 2 of PPARD gene. Functional characterization using transient transfection, reporter assay and CTCF binding confirmed the insulator status. However, the predicted enhancer element showed repressor/silencer activity. Finally, we observed a potential interaction between these two cis-regulatory elements which is in agreement with 5C-Encyclopedia of DNA Elements data. We report two functionally validated cis-regulatory elements in PPARD gene which will aid in understanding its regulation and role in metabolic functions.