Cadmium exposure and the epigenome: Exposure-associated patterns of DNA methylation in leukocytes from mother-baby pairs

Alison P. Sanders, Lisa Smeester, Daniel Rojas, Tristan DeBussycher, Michael C. Wu, Fred A. Wright, Yi Hui Zhou, Jessica E. Laine, Julia E. Rager, Geeta K. Swamy, Allison Ashley-Koch, Marie Lynn Miranda, Rebecca C. Fry

Research output: Contribution to journalArticlepeer-review

126 Scopus citations

Abstract

Cadmium (Cd) is prevalent in the environment yet understudied as a developmental toxicant. Cd partially crosses the placental barrier from mother to fetus and is linked to detrimental effects in newborns. Here we examine the relationship between levels of Cd during pregnancy and 5-methylcytosine (5mC) levels in leukocyte DNA collected from 17 mothernewborn pairs. The methylation of cytosines is an epigenetic mechanism known to impact transcriptional signaling and influence health endpoints. A methylated cytosine-guanine (CpG) island recovery assay was used to assess over 4.6 million sites spanning 16, 421 CpG islands. Exposure to Cd was classified for each mother-newborn pair according to maternal blood levels and compared with levels of cotinine. Subsets of genes were identified that showed altered DNA methylation levels in their promoter regions in fetal DNA associated with levels of Cd (n = 61), cotinine (n = 366), or both (n = 30). Likewise, in maternal DNA, differentially methylated genes were identified that were associated with Cd (n = 92) or cotinine (n = 134) levels. While the gene sets were largely distinct between maternal and fetal DNA, functional similarities at the biological pathway level were identified including an enrichment of genes that encode for proteins that control transcriptional regulation and apoptosis. Furthermore, conserved DNA motifs with sequence similarity to specific transcription factor binding sites were identified within the CpG islands of the gene sets. This study provides evidence for distinct patterns of DNA methylation or "footprints" in fetal and maternal DNA associated with exposure to Cd.

Original languageEnglish
Pages (from-to)212-221
Number of pages10
JournalEpigenetics
Volume9
Issue number2
DOIs
StatePublished - 2014

Keywords

  • Cadmium
  • Cigarette smoke
  • Cord blood
  • Epigenetics
  • Heavy metal
  • Maternal blood
  • Methylation
  • Pregnancy

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