title: Active and passive demethylation of male and female pronuclear DNA in the mammalian zygote.
abstract: The epigenomes of mammalian sperm and oocytes, characterized by gamete-specific 5-methylcytosine (5mC) patterns, are reprogrammed during early embryogenesis to establish full developmental potential. Previous studies have suggested that the paternal genome is actively demethylated in the zygote while the maternal genome undergoes subsequent passive demethylation via DNA replication during cleavage. Active demethylation is known to depend on 5mC oxidation by Tet dioxygenases and excision of oxidized bases by thymine DNA glycosylase (TDG). Here we show that both maternal and paternal genomes undergo widespread active and passive demethylation in zygotes before the first mitotic division. Passive demethylation was blocked by the replication inhibitor aphidicolin, and active demethylation was abrogated by deletion of Tet3 in both pronuclei. At actively demethylated loci, 5mCs were processed to unmodified cytosines. Surprisingly, the demethylation process was unaffected by the deletion of TDG from the zygote, suggesting the existence of other demethylation mechanisms downstream of Tet3-mediated oxidation.
authors.affiliation: Biodynamic Optical Imaging Center, College of Life Sciences, Peking University, Beijing 100871, China; State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Guo
authors.affiliation: Biodynamic Optical Imaging Center, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Xianlong
authors.initials: X
authors.lastname: Li
authors.affiliation: Group of Epigenetic Reprogramming, State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Liang
authors.affiliation: State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Li
authors.affiliation: Biodynamic Optical Imaging Center, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhu
authors.affiliation: Biodynamic Optical Imaging Center, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Hongshan
authors.initials: H
authors.lastname: Guo
authors.affiliation: Biodynamic Optical Imaging Center, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Xinglong
authors.initials: X
authors.lastname: Wu
authors.affiliation: Biodynamic Optical Imaging Center, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Wen
authors.affiliation: State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Tian-Peng
authors.initials: TP
authors.lastname: Gu
authors.affiliation: Biodynamic Optical Imaging Center, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Boqiang
authors.initials: B
authors.lastname: Hu
authors.affiliation: Centre for Molecular Biosciences, School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, UK.
authors.forename: Colum P
authors.initials: CP
authors.lastname: Walsh
authors.affiliation: Group of Epigenetic Reprogramming, State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China. Electronic address: jsli@sibcb.ac.cn.
authors.forename: Jinsong
authors.initials: J
authors.lastname: Li
authors.affiliation: Biodynamic Optical Imaging Center, College of Life Sciences, Peking University, Beijing 100871, China; Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, Peking University, Beijing 100871, China. Electronic address: tangfuchou@pku.edu.cn.
authors.forename: Fuchou
authors.initials: F
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China. Electronic address: glxu@sibcb.ac.cn.
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Xu
mesh_terms: D044503:5-Methylcytosine / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D019175:DNA Methylation / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism; D049308:Dioxygenases; D005260:Female; D017353:Gene Deletion; D056426:Genetic Loci; D016678:Genome / Q000235:genetics; D008297:Male; D008322:Mammals / Q000235:genetics*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D015203:Reproducibility of Results; D012098:Reproduction / Q000235:genetics; D017422:Sequence Analysis, DNA; D044502:Thymine DNA Glycosylase / Q000378:metabolism; D015053:Zygote / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D044503:5-Methylcytosine; D049308:Dioxygenases; C551915:Tet3 protein, mouse; D044502:Thymine DNA Glycosylase