title: Ascorbic acid enhances Tet-mediated 5-methylcytosine oxidation and promotes DNA demethylation in mammals.
abstract: DNA hydroxymethylation and its mediated DNA demethylation are critical for multiple cellular processes, for example, nuclear reprogramming, embryonic development, and many diseases. Here, we demonstrate that a vital nutrient ascorbic acid (AA), or vitamin C (Vc), can directly enhance the catalytic activity of Tet dioxygenases for the oxidation of 5-methylcytosine (5mC). As evidenced by changes in intrinsic fluorescence and catalytic activity of Tet2 protein caused by AA and its oxidation-resistant derivatives, we further show that AA can uniquely interact with the C-terminal catalytic domain of Tet enzymes, which probably promotes their folding and/or recycling of the cofactor Fe(2+). Other strong reducing chemicals do not have a similar effect. These results suggest that AA also acts as a cofactor of Tet enzymes. In mouse embryonic stem cells, AA significantly increases the levels of all 5mC oxidation products, particularly 5-formylcytosine and 5-carboxylcytosine (by more than an order of magnitude), leading to a global loss of 5mC (∼40%). In cells deleted of the Tet1 and Tet2 genes, AA alters neither 5mC oxidation nor the overall level of 5mC. The AA effects are however restored when Tet2 is re-expressed in the Tet-deficient cells. The enhancing effects of AA on 5mC oxidation and DNA demethylation are also observed in a mouse model deficient in AA synthesis. Our data establish a direct link among AA, Tet, and DNA methylation, thus revealing a role of AA in the regulation of DNA modifications.
authors.affiliation: The State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Ruichuan
authors.initials: R
authors.lastname: Yin
authors.forename: Shi-Qing
authors.initials: SQ
authors.lastname: Mao
authors.forename: Bailin
authors.initials: B
authors.lastname: Zhao
authors.forename: Zechen
authors.initials: Z
authors.lastname: Chong
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.forename: Chao
authors.initials: C
authors.lastname: Zhao
authors.forename: Dapeng
authors.initials: D
authors.lastname: Zhang
authors.forename: Hua
authors.initials: H
authors.lastname: Huang
authors.forename: Juan
authors.initials: J
authors.lastname: Gao
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.forename: Yan
authors.initials: Y
authors.lastname: Jiao
authors.forename: Cuiping
authors.initials: C
authors.lastname: Li
authors.forename: Shengquan
authors.initials: S
authors.lastname: Liu
authors.forename: Danni
authors.initials: D
authors.lastname: Wu
authors.forename: Weikuan
authors.initials: W
authors.lastname: Gu
authors.forename: Yun-Gui
authors.initials: YG
authors.lastname: Yang
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Xu
authors.forename: Hailin
authors.initials: H
authors.lastname: Wang
mesh_terms: D044503:5-Methylcytosine / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001205:Ascorbic Acid / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000378:metabolism*; D049308:Dioxygenases; D051379:Mice; D010084:Oxidation-Reduction; D011518:Proto-Oncogene Proteins / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; C540839:TET1 protein, mouse; D044503:5-Methylcytosine; D004247:DNA; D049308:Dioxygenases; C551914:Tet2 protein, mouse; D001205:Ascorbic Acid