Subtle decreases in DNA methylation and gene expression at the mouse Igf2 locus following prenatal alcohol exposure: effects of a methyl-supplemented diet.
C57BL/6J (B6) mice are susceptible to in utero growth retardation and a number of morphological malformations following prenatal alcohol exposure, while DBA/2J (D2) mice are relatively resistant. We have previously shown that genomic imprinting may play a role in differential sensitivity between B6 and D2. The best-characterized mechanism mediating genomic imprinting is differential DNA methylation. In the present study we examined DNA methylation and gene expression, in both embryonic and placental tissue, at the mouse Igf2 locus following in utero ethanol exposure. We also examined the effects of a methyl-supplemented diet on methylation and ethanol teratogenesis. In embryos from susceptible B6 mice, we found small decreases in DNA methylation at four CpG sites in one of the differentially methylated regions of the Igf2 locus; only one of the four sites showed a statistically significant decrease. We observed no significant decreases in methylation in placentae. All Igf2 transcripts showed approximately 1.5-fold decreases following intrauterine alcohol exposure. Placing dams on a methyl-supplemented diet before pregnancy and throughout gestation brought methylation back up to control levels. Methyl supplementation also resulted in lower prenatal mortality, greater prenatal growth, and decreased digit malformations; it dramatically reduced vertebral malformations. Thus, although prenatal alcohol had only small effects on DNA methylation at the Igf2 locus, placing dams on a methyl-supplemented diet partially ameliorated ethanol teratogenesis.
Downing
Chris
C
Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80309-0447, USA. cdowning@pharmacy.isu.edu
Johnson
Thomas E
TE
Larson
Colin
C
Leakey
Tatiana I
TI
Siegfried
Rachel N
RN
Rafferty
Tonya M
TM
Cooney
Craig A
CA
D000014:Abnormalities, Drug-Induced / Q000209:etiology / Q000517:prevention & control; D000818:Animals; D001622:Betaine / Q000008:administration & dosage; D002794:Choline / Q000008:administration & dosage; D019175:DNA Methylation / Q000187:drug effects*; D004032:Diet; D004351:Drug Resistance; D000431:Ethanol / Q000008:administration & dosage / Q000633:toxicity*; D005260:Female; D005313:Fetal Death / Q000517:prevention & control; D047109:Fetal Development / Q000187:drug effects; D005492:Folic Acid / Q000008:administration & dosage; D015870:Gene Expression / Q000187:drug effects*; D018392:Genomic Imprinting; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008297:Male; D008431:Maternal-Fetal Exchange; D000432:Methanol / Q000008:administration & dosage; D008745:Methylation; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D011247:Pregnancy; D013045:Species Specificity; D014805:Vitamin B 12 / Q000008:administration & dosage
D000431:Ethanol; D001622:Betaine; D007335:Insulin-Like Growth Factor II; D005492:Folic Acid; D002794:Choline; D014805:Vitamin B 12; D000432:Methanol