NIEHS and NTP report life experiences may alter DNA methylation
Scientists at NIEHS and the National Toxicology Program (NTP), along with collaborators, reported that DNA sequence may determine where methylation events occur, and that life events such as pregnancy could alter DNA methylation patterns. The researchers used inbred mice to examine methylation, which is the addition of methyl groups onto DNA, in regions where the nucleotide cytosine is followed by a phosphate and the nucleotide guanine. Methylation of these areas, known as CpG sites, may serve as an epigenetic record of life events in body cells.
Researchers intercrossed two inbred mouse strains, C57BL/6N and C3H/HeN, and measured DNA methylation patterns in the livers of parents and offspring using whole-genome bisulfite sequencing. They found that DNA methylation patterns were closely linked to the genetic makeup of the animal, which is known as genotype. These patterns were unchanged when passed to male and female offspring. However, in female animals that had experienced pregnancy, hundreds of DNA sites showed decreased methylation compared with virgin females.
These findings suggest that genetics influences DNA methylation patterns and that major life events may leave a distinct methylation signature. Although the team has not determined exactly how these female mice had a loss of DNA methylation, the work bolsters the importance of epigenetics in influencing gene regulation. (RA)
Citation: Grimm SA, Shimbo T, Takaku M, Thomas JW, Auerbach S, Bennett BD, Bucher JR, Burkholder AB, Day F, Du Y, Duncan CG, French JE, Foley JF, Li J, Merrick BA, Tice RR, Wang T, Xu X, NISC Comparative Sequencing Program, Buchel PR, Fargo DC, Mullikin JC, Wade PA. 2019. DNA methylation in mice is influenced by genetics as well as sex and life experience. Nat Commun 10(1):305.