ABSTRACT
BACKGROUND: Prenatal alcohol exposure is recognized for altering DNA methylation profiles of brain cells during development, and to be part of the molecular basis underpinning Fetal Alcohol Spectrum Disorder (FASD) etiology. However, we have negligible information on the effects of alcohol exposure during pre-implantation, the early embryonic window marked with dynamic DNA methylation reprogramming, and on how this may rewire the brain developmental program. RESULTS: Using a pre-clinical in vivo mouse model, we show that a binge-like alcohol exposure during pre-implantation at the 8-cell stage leads to surge in morphological brain defects and adverse developmental outcomes during fetal life. Genome-wide DNA methylation analyses of fetal forebrains uncovered sex-specific alterations, including partial loss of DNA methylation maintenance at imprinting control regions, and abnormal de novo DNA methylation profiles in various biological pathways (e.g., neural/brain development). CONCLUSION: These findings support that alcohol-induced DNA methylation programming deviations during pre-implantation could contribute to the manifestation of neurodevelopmental phenotypes associated with FASD.
Subject(s)
Alcohol Drinking/adverse effects , DNA Damage/drug effects , DNA Damage/genetics , DNA Methylation/drug effects , DNA Methylation/genetics , Fetal Alcohol Spectrum Disorders/genetics , Prosencephalon/metabolism , Adult , Animals , Disease Models, Animal , Embryonic Development/drug effects , Embryonic Development/genetics , Epigenesis, Genetic , Female , Gene Expression Regulation, Developmental/drug effects , Gene Expression Regulation, Developmental/genetics , Humans , Male , Mice , Phenotype , Pregnancy , Prenatal Exposure Delayed EffectsABSTRACT
Genetic variants in one-carbon folate metabolism have been identified as risk factors for disease because they may impair the production or use of one-carbon folates required for nucleotide synthesis and methylation. p.R653Q (1958G>A) is a single-nucleotide polymorphism (SNP) in the 10-formyltetrahydrofolate (formylTHF) synthetase domain of the trifunctional enzyme MTHFD1; this domain produces the formylTHF which is required for the de novo synthesis of purines. Approximately 20% of Caucasians are homozygous for the Q allele. MTHFD1 p.R653Q has been proposed as a risk factor for neural tube defects (NTDs), congenital heart defects (CHDs) and pregnancy losses. We have generated a novel mouse model in which the MTHFD1 synthetase activity is inactivated without affecting protein expression or the other activities of this enzyme. Complete loss of synthetase activity (Mthfd1S(-/-)) is incompatible with life; embryos die shortly after 10.5 days gestation, and are developmentally delayed or abnormal. The proportion of 10-formylTHF in the plasma and liver of Mthfd1S(+/-) mice is reduced (P < 0.05), and de novo purine synthesis is impaired in Mthfd1S(+/-) mouse embryonic fibroblasts (MEFs, P < 0.005). Female Mthfd1S(+/-) mice had decreased neutrophil counts (P < 0.05) during pregnancy and increased incidence of developmental defects in embryos (P = 0.052). These findings suggest that synthetase deficiency may lead to pregnancy complications through decreased purine synthesis and reduced cellular proliferation. Additional investigation of the impact of synthetase polymorphisms on human pregnancy is warranted.
Subject(s)
Aminohydrolases/genetics , Aminohydrolases/metabolism , Embryonic Development/genetics , Formate-Tetrahydrofolate Ligase/genetics , Methylenetetrahydrofolate Dehydrogenase (NADP)/genetics , Methylenetetrahydrofolate Dehydrogenase (NADP)/metabolism , Multienzyme Complexes/genetics , Multienzyme Complexes/metabolism , Pregnancy Complications/genetics , Purines/biosynthesis , Aminohydrolases/deficiency , Animals , Cell Proliferation , Cells, Cultured , Choline/metabolism , Congenital Abnormalities/genetics , Embryo Loss , Female , Folic Acid/metabolism , Formate-Tetrahydrofolate Ligase/deficiency , Formate-Tetrahydrofolate Ligase/metabolism , Gene Knock-In Techniques , Genetic Variation , Humans , Leucovorin/analogs & derivatives , Leucovorin/chemistry , Leukocyte Count , Male , Methionine/metabolism , Methylenetetrahydrofolate Dehydrogenase (NADP)/deficiency , Methylenetetrahydrofolate Reductase (NADPH2)/metabolism , Mice , Mice, Inbred C57BL , Models, Animal , Multienzyme Complexes/deficiency , Multifunctional Enzymes/genetics , Multifunctional Enzymes/metabolism , Mutagenesis, Site-Directed , Polymorphism, Single Nucleotide , Pregnancy , Pregnancy Complications/metabolismABSTRACT
Members of the transmembrane emp24 domain (Tmed)/p24 family of proteins are required for transport of proteins between the endoplasmic reticulum and the Golgi. One member of this family, Tmed2/p24ß1, is expressed during placental development in mice and its expression is required for normal development of the labyrinth layer. Although TMED2 is conserved in humans, little is known about its expression and function in human placenta. We examined TMED2 expression in human placenta between 5.5 and 40 weeks of gestation and showed that TMED2 is expressed in syncytiotrophoblast, cytotrophoblast, and stromal cells. We also found high levels of TMED2 expression in BeWo but not in JEG-3 choriocarcinoma cell line. We used the BeWo cell line to determine TMED2 subcellular localization in placental cells and show its co-localization with the endoplasmic reticulum Golgi intermediate compartment. Our findings show conservation of TMED2 expression in human placenta and suggest that this protein may also play a role during placental development in humans.
