Poster Presentation Epigenetics 2013

Maternal folate status as a modifier of epigenetic profile in human neonatal CD4+ T cells (#214)

Manori Amarasekera 1 , Sarah Ashley 2 3 , Hani Harab 4 , Susan Prescott 1 , David Martino 2 5 , Richard Saffery 2 5
  1. School of Paediatrics and Child Health, University of Western Australia, Perth
  2. Murdoch Childrens Research Institute, Parkville, VIC, Australia
  3. Monash Institute of Medical Research, Monash University, Clayton, VIC
  4. Institute of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps University of Marburg, Marburg, Germany
  5. Department of Paediatrics, The University of Melbourne, Parkville

Background: The prenatal environment is fundamental in shaping the fetal epigenome. Adverse exposures strongly impact the fetal developmental program, potentially increasing disease predispositions. On such factor is maternal folate, involved in regulating DNA methylation and gene expression in early development. Supplementation during pregnancy is used to protect against neural tube defects, but has been linked to altered epigenetics in both animal and human studies.  

Methods: We compared DNA methylation in two immune cell types, CD4+ T-cells & Antigen Presenting Cells (APCs), isolated from cord blood from neonates exposed to high (HF) and low (LF) levels of maternal folate. The sample population (n=23) was derived from a prospective birth cohort (n=628) recruited through a pediatric hospital allergy prevention program. HF & LF groups were selected from first and third quartiles of the maternal serum folate distribution. Genome-wide DNA methylation was measured using the Illumina Human Methylation 450k array, histone acetylation (H3 and H4) in CD4+ cells using immunoprecipitation and validation and replication of array findings performed on Sequenom EpiTyper.

Results: Comparison of genome-wide DNA methylation profiles in both cell types revealed a differentially methylated region (DMR) in chromosome 6. It consisted of 20 differentially methylated CpGs proximal to the promoter of ZFP57, which is implicated in maintenance of methylation at imprinted loci. Methylation levels were lower in HF, and histone acetylation was higher. This was validated in the same cohort using the Sequenom EpiTyper, and replicated independently in a separate group of neonatal DNA samples (n=19).

Conclusion: In this study we found evidence that maternal folate intake during pregnancy altered DNA methylation of the ZFP57 gene in neonatal blood cells. This is associated with increasing histone acetylation indicative of altered transcriptional activity. ZFP57 regulates DNA methylation levels at imprinted loci, thus these data provide a potential mechanism for the observed refractory nature of imprinting-associated methylation to decreased one carbon-donor bioavailability.