Uracil-DNA Glycosylase Is Involved in DNA Demethylation and Required for Embryonic Development in the Zebrafish Embryo

• Published in: The Journal of biological chemistry Vol. 289; no. 22; pp. 15463 - 15473
• Main Authors: Wu, Di, Chen, Luxi, Sun, Qingrui, Wu, Xiaotong, Jia, Shunji, Meng, Anming
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 30.05.2014; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Base Excision Repair (BER); Blastomeres - physiology; Cellular Reprogramming - physiology; Chromatin - metabolism; Danio rerio; Developmental Biology; DNA Demethylation; DNA Glycosylase; DNA Methylation - physiology; DNA Repair - physiology; DNA Transcription; Embryo; Embryo, Nonmammalian - physiology; Gene Expression Regulation, Developmental; Gene Knockdown Techniques; Nuclear Reprogramming; Transcription, Genetic - physiology; Transcriptome; Uracil - metabolism; Uracil-DNA Glycosidase - genetics; Uracil-DNA Glycosidase - metabolism; Zebrafish; Zebrafish - embryology; Zebrafish - genetics; Zygotic Genome Activation; Zygotic Genome Activation; Embryo; Nuclear Reprogramming; DNA Glycosylase; Base Excision Repair (BER); DNA Demethylation; Zebrafish; DNA Transcription
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.561019

Uracil-DNA glycosylase (Ung) is a component of the base excision repair process and has the ability to remove uracil from U:G mispairs in DNA. However, its implications in development of vertebrate embryos are poorly understood. In this study, we found that zebrafish uracil-DNA glycosylase a (Unga) is maternally expressed at high levels and accumulated in nuclei during cleavage and blastulation periods. Knockdown of unga in zebrafish embryos causes an increase of the global DNA methylation level concomitantly with a reduction of overall transcriptional activity in the nucleus, ultimately resulting in embryonic lethality during segmentation period. Conversely, unga overexpression is sufficient to reduce the global DNA methylation level, to increase H3K4me3 and H3K27me3 marks, and to activate genome transcription. Furthermore, overexpression of unga(D132A) mRNA, encoding a mutant Unga without DNA glycosylase activity, does not affect global DNA methylation level, indicating that its involvement in DNA demethylation is dependent on its glycosylase activity. These results together suggest that Unga is implicated in postfertilization genomic DNA demethylation, zygotic gene transcription, and normal embryonic development in zebrafish. Ung implication in DNA demethylation and embryonic development is poorly understood. unga knockdown in the zebrafish embryo increases global DNA methylation level, inhibits transcription, and causes embryonic lethality whereas its overexpression produces opposite effects on DNA methylation and transcription. Unga is involved in postfertilization DNA demethylation and transcription. The findings shed new light on Ung function in DNA demethylation and embryonic development.