Mono-2-ethylhexyl phthalate (MEHP) alters histiotrophic nutrition pathways and epigenetic processes in the developing conceptus.
Histiotrophic nutrition pathways (HNPs) are processes by which the organogenesis-stage conceptus obtains nutrients, amino acids, vitamins and cofactors required for protein biosynthesis and metabolic activities. Nutrients are captured from the maternal milieu as whole proteins and cargoes via receptor-mediated endocytosis in the visceral yolk sac (VYS), degraded by lysosomal proteolysis and delivered to the developing embryo (EMB). Several nutrients obtained by HNPs are required substrates for one-carbon (C1) metabolism and supply methyl groups required for epigenetic processes, including DNA and histone methylation. Increased availability of methyl donors has been associated with reduced risk for neural tube defects (NTDs). Here, we show that mono-2-ethylhexyl phthalate (MEHP) treatment (100 or 250μM) alters HNPs, C1 metabolism and epigenetic programming in the organogenesis-stage conceptus. Specifically, 3-h MEHP treatment of mouse EMBs in whole culture resulted in dose-dependent reduction of HNP activity in the conceptus. To observe nutrient consequences of decreased HNP function, C1 components and substrates and epigenetic outcomes were quantified at 24h. Treatment with 100-μM MEHP resulted in decreased dietary methyl donor concentrations, while treatment with 100- or 250-μM MEHP resulted in dose-dependent elevated C1 products and substrates. In MEHP-treated EMBs with NTDs, H3K4 methylation was significantly increased, while no effects were seen in treated VYS. DNA methylation was reduced in MEHP-treated EMB with and without NTDs. This research suggests that environmental toxicants such as MEHP decrease embryonic nutrition in a time-dependent manner and that epigenetic consequences of HNP disruption may be exacerbated in EMB with NTDs.
Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, 48109-2029.
Karilyn E
KE
Sant
Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, 48109-2029.
Dana C
DC
Dolinoy
Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, 48109-2029.
Joseph L
JL
Jilek
Department of Pharmacology, Biomedical Mass Spectrometry Facility, University of Michigan, Ann Arbor, Michigan, 48109-5632.
Brian J
BJ
Shay
Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, 48109-2029. Electronic address: charris@umich.edu.
Craig
C
Harris
D000818:Animals; D019175:DNA Methylation; D004051:Diethylhexyl Phthalate / Q000031:analogs & derivatives* / Q000494:pharmacology; D047108:Embryonic Development / Q000187:drug effects*; D044127:Epigenesis, Genetic / Q000187:drug effects*; D005260:Female; D006657:Histones / Q000378:metabolism; D051379:Mice; D009752:Nutritional Status / Q000187:drug effects*; D011247:Pregnancy
D006657:Histones; D004051:Diethylhexyl Phthalate; C016599:mono-(2-ethylhexyl)phthalate
DNA methylation; Embryonic development; Histiotrophic nutrition; Histone methylation; Neural tube defects; One-carbon metabolism