ZFIN ID: ZDB-PUB-141224-2
No Evidence for AID/MBD4-Coupled DNA Demethylation in Zebrafish Embryos
Shimoda, N., Hirose, K., Kaneto, R., Izawa, T., Yokoi, H., Hashimoto, N., Kikuchi, Y.
Date: 2014
Source: PLoS One   9: e114816 (Journal)
Registered Authors: Kikuchi, Yutaka, Shimoda, Nobuyoshi, Yokoi, Hayato
Keywords: none
MeSH Terms:
  • Alternative Splicing/drug effects
  • Alternative Splicing/genetics
  • Animals
  • CpG Islands/genetics
  • Cytidine Deaminase/genetics
  • Cytidine Deaminase/metabolism*
  • DNA Glycosylases/genetics
  • DNA Glycosylases/metabolism*
  • DNA Methylation/drug effects
  • DNA Methylation/genetics*
  • Embryo, Nonmammalian/drug effects
  • Embryo, Nonmammalian/metabolism*
  • Fertilization/genetics
  • Gene Expression Regulation, Developmental/drug effects
  • Genome
  • Injections
  • Morpholinos/pharmacology
  • Neurons/drug effects
  • Neurons/metabolism
  • Ovum/drug effects
  • Ovum/metabolism
  • Protein Structure, Tertiary
  • Transcription, Genetic/drug effects
  • Zebrafish/embryology*
  • Zebrafish/genetics*
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism*
PubMed: 25536520 Full text @ PLoS One
The mechanisms responsible for active DNA demethylation remain elusive in Metazoa. A previous study that utilized zebrafish embryos provided a potent mechanism for active demethylation in which three proteins, AID, MBD4, and GADD45 are involved. We recently found age-dependent DNA hypomethylation in zebrafish, and it prompted us to examine if AID and MBD4 could be involved in the phenomenon. Unexpectedly, however, we found that most of the findings in the previous study were not reproducible. First, the injection of a methylated DNA fragment into zebrafish eggs did not affect either the methylation of genomic DNA, injected methylated DNA itself, or several loci tested or the expression level of aid, which has been shown to play a role in demethylation. Second, aberrant methylation was not observed at certain CpG islands following the injection of antisense morpholino oligonucleotides against aid and mbd4. Furthermore, we demonstrated that zebrafish MBD4 cDNA lacked a coding region for the methyl-CpG binding domain, which was assumed to be necessary for guidance to target regions. Taken together, we concluded that there is currently no evidence to support the proposed roles of AID and MBD4 in active demethylation in zebrafish embryos.