title: Epigenetic programming in the preimplantation rat embryo is disrupted by chronic paternal cyclophosphamide exposure.
abstract: Preconceptional paternal exposure to cyclophosphamide, a widely used anticancer agent, leads to increases in embryo loss, malformations, and behavioral deficits in offspring; these abnormalities are transmissible to subsequent generations [Auroux, M., Dulioust, E., Selva, J. & Rince, P. (1990) Mutat. Res. 229, 189-200]. Little information exists on the mechanisms underlying this male-mediated developmental toxicity. We assessed the impact of paternal cyclophosphamide exposure on the dynamic regulation of histone H4 acetylation at lysine 5 and DNA methylation in preimplantation rat embryos. Zygotes sired by drug-treated males displayed advanced developmental progression, increased pronuclear areas, and disruption of the epigenetic programming of both parental genomes. Early postfertilization zygotic pronuclei were hyperacetylated; by mid-zygotic development, male pronuclei were dramatically hypomethylated, whereas female pronuclei were hypermethylated. Micronuclei were substantially elevated, and histone H4 acetylation at lysine 5 localization to the nuclear periphery was disrupted in two-cell embryos fertilized by cyclophosphamide-exposed spermatozoa. This finding demonstrates that paternal exposure to this drug induces aberrant epigenetic programming in early embryos. We hypothesize that disturbances in epigenetic programming contribute to heritable instabilities later in development, emphasizing the importance of epigenetic risk assessment after chemotherapy.
authors.affiliation: Departments of Pharmacology and Therapeutics and Obstetrics and Gynecology, McGill University, 3655 Promenade Sir-William-Osler, Montreal, QC, Canada H3G 1Y6.
authors.forename: Tara S
authors.initials: TS
authors.lastname: Barton
authors.forename: Bernard
authors.initials: B
authors.lastname: Robaire
authors.forename: Barbara F
authors.initials: BF
authors.lastname: Hales
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D001755:Blastocyst / Q000187:drug effects* / Q000502:physiology; D003520:Cyclophosphamide / Q000633:toxicity*; D019175:DNA Methylation / Q000187:drug effects; D044127:Epigenesis, Genetic / Q000187:drug effects* / Q000502:physiology; D005455:Fluorescent Antibody Technique; D006657:Histones / Q000378:metabolism; D008297:Male; D015162:Micronucleus Tests; D018613:Microscopy, Confocal; D018812:Paternal Exposure; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D006657:Histones; D003520:Cyclophosphamide