title: Uracil-DNA Glycosylase UNG Promotes Tet-mediated DNA Demethylation.
abstract: In mammals, active DNA demethylation involves oxidation of 5-methylcytosine (5mC) into 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) by Tet dioxygenases and excision of these two oxidized bases by thymine DNA glycosylase (TDG). Although TDG is essential for active demethylation in embryonic stem cells and induced pluripotent stem cells, it is hardly expressed in mouse zygotes and dispensable in pronuclear DNA demethylation. To search for other factors that might contribute to demethylation in mammalian cells, we performed a functional genomics screen based on a methylated luciferase reporter assay. UNG2, one of the glycosylases known to excise uracil residues from DNA, was found to reduce DNA methylation, thus activating transcription of a methylation-silenced reporter gene when co-transfected with Tet2 into HEK293T cells. Interestingly, UNG2 could decrease 5caC from the genomic DNA and a reporter plasmid in transfected cells, like TDG. Furthermore, deficiency in Ung partially impaired DNA demethylation in mouse zygotes. Our results suggest that UNG might be involved in Tet-mediated DNA demethylation.
authors.affiliation: From the The State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Jian-Huang
authors.initials: JH
authors.lastname: Xue
authors.affiliation: From the The State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China, the School of Life Science, Fudan University, Shanghai 200433, China.
authors.forename: Gui-Fang
authors.initials: GF
authors.lastname: Xu
authors.affiliation: From the The State Key Laboratory of Molecular Biology, 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: From the The State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Guo-Dong
authors.initials: GD
authors.lastname: Chen
authors.affiliation: From the The State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Bin-Bin
authors.initials: BB
authors.lastname: Han
authors.affiliation: From the The State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Zhi-Mei
authors.initials: ZM
authors.lastname: Xu
authors.affiliation: the Department of Microbiology, Clinic for Diagnostics and Intervention, Oslo University Hospital, Rikshospitalet, P. O. Box 4950, Nydalen, N-0424 Oslo, Norway.
authors.forename: Magnar
authors.initials: M
authors.lastname: Bjørås
authors.affiliation: the Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway, and.
authors.forename: Hans E
authors.initials: HE
authors.lastname: Krokan
authors.affiliation: From the The State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China, the School of Life Science and Technology, ShanghaiTech University, 319 Yue Yang Road, Shanghai 200031, China.
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Xu
authors.affiliation: From the The State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China, yrdu@sibcb.ac.cn.
authors.forename: Ya-Rui
authors.initials: YR
authors.lastname: Du
mesh_terms: D000818:Animals; D003596:Cytosine / Q000031:analogs & derivatives; D004247:DNA / Q000378:metabolism; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000378:metabolism*; D049308:Dioxygenases; D017930:Genes, Reporter; D056426:Genetic Loci; D015894:Genome, Human; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D010957:Plasmids / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D014162:Transfection; D014498:Uracil / Q000378:metabolism; D051981:Uracil-DNA Glycosidase / Q000172:deficiency / Q000378:metabolism*; D015053:Zygote / Q000378:metabolism
chemical_list: C560974:5-carboxylcytosine; D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D014498:Uracil; D003596:Cytosine; D004247:DNA; D049308:Dioxygenases; C551914:Tet2 protein, mouse; D051981:Uracil-DNA Glycosidase
keywords: DNA demethylation; DNA methylation; Tet; UNG2; base excision repair (BER); gene knockout; transcription regulation