Li Yan, Córdoba-Cañero Dolores, Qian Weiqiang, Zhu Xiaohong, Tang Kai, Zhang Huiming, Ariza Rafael R, Roldán-Arjona Teresa, Zhu Jian-Kang
Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Science, Peking University, Beijing, China.
Department of Genetics, University of Córdoba/Maimonides Institute for Biomedical Research of Cordoba (IMIBIC)/Reina Sofía University Hospital, Córdoba, Spain.
PLoS Genet. 2015 Jan 8;11(1):e1004905. doi: 10.1371/journal.pgen.1004905. eCollection 2015 Jan.
Active DNA demethylation in plants occurs through base excision repair, beginning with removal of methylated cytosine by the ROS1/DME subfamily of 5-methylcytosine DNA glycosylases. Active DNA demethylation in animals requires the DNA glycosylase TDG or MBD4, which functions after oxidation or deamination of 5-methylcytosine, respectively. However, little is known about the steps following DNA glycosylase action in the active DNA demethylation pathways in plants and animals. We show here that the Arabidopsis APE1L protein has apurinic/apyrimidinic endonuclease activities and functions downstream of ROS1 and DME. APE1L and ROS1 interact in vitro and co-localize in vivo. Whole genome bisulfite sequencing of ape1l mutant plants revealed widespread alterations in DNA methylation. We show that the ape1l/zdp double mutant displays embryonic lethality. Notably, the ape1l+/-zdp-/- mutant shows a maternal-effect lethality phenotype. APE1L and the DNA phosphatase ZDP are required for FWA and MEA gene imprinting in the endosperm and are important for seed development. Thus, APE1L is a new component of the active DNA demethylation pathway and, together with ZDP, regulates gene imprinting in Arabidopsis.
植物中的主动DNA去甲基化通过碱基切除修复发生，起始于由5-甲基胞嘧啶DNA糖基化酶的ROS1/DME亚家族去除甲基化的胞嘧啶。动物中的主动DNA去甲基化需要DNA糖基化酶TDG或MBD4，它们分别在5-甲基胞嘧啶氧化或脱氨后发挥作用。然而，关于植物和动物主动DNA去甲基化途径中DNA糖基化酶作用后的步骤，人们知之甚少。我们在此表明，拟南芥APE1L蛋白具有脱嘌呤/脱嘧啶内切核酸酶活性，并在ROS1和DME的下游发挥作用。APE1L和ROS1在体外相互作用，在体内共定位。ape1l突变体植物的全基因组亚硫酸氢盐测序揭示了DNA甲基化的广泛改变。我们表明，ape1l/zdp双突变体表现出胚胎致死性。值得注意的是，ape1l+/-zdp-/-突变体表现出母本效应致死表型。APE1L和DNA磷酸酶ZDP是胚乳中FWA和MEA基因印记所必需的，并且对种子发育很重要。因此，APE1L是主动DNA去甲基化途径的一个新组分，并且与ZDP一起调节拟南芥中的基因印记。
