Masako Tada1, Ayaka Hayashi2, Yumi Asano2, Musashi Kubiura-Ichimaru3, Takamasa Ito3, Miho Yoshii3, Hiroshi Kimura4, Yoichi Matsuda5, Mitsuo Oshimura2. 1. Stem Cells and Reprogramming Laboratory, Department of Biology, Faculty of Science, Toho University, Miyama 2-2-1, Funabashi, Chiba, 274-8510, Japan. masako.tada@sci.toho-u.ac.jp. 2. Chromosome Engineering Research Center, Tottori University, Yonago, 683-8503, Japan. 3. Stem Cells and Reprogramming Laboratory, Department of Biology, Faculty of Science, Toho University, Miyama 2-2-1, Funabashi, Chiba, 274-8510, Japan. 4. Cell Biology Unit, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, 226-8501, Japan. 5. Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
Abstract
BACKGROUND: DNA methylation is a significant epigenetic modification that is evolutionarily conserved in various species and often serves as a repressive mark for transcription. DNA methylation levels and patterns are regulated by a balance of opposing enzyme functions, DNA methyltransferases, DNMT1/3A/3B and methylcytosine dioxygenases, TET1/2/3. In mice, the TET enzyme converts DNA cytosine methylation (5mC) to 5-hydroxymethylcytosine (5hmC) at the beginning of fertilisation and gastrulation and initiates a global loss of 5mC, while the 5mC level is increased on the onset of cell differentiation during early embryonic development. OBJECTIVE: Global loss and gain of DNA methylation may be differently regulated in diverged species. METHODS: Chicken B-cell lymphoma DT40 cells were used as an avian model to compare differences in the overall regulation of DNA modification with mammals. RESULTS: We found that DNA methylation is maintained at high levels in DT40 cells through compact chromatin formation, which inhibits TET-mediated demethylation. Human and mouse chromosomes introduced into DT40 cells by cell fusion lost the majority of 5mC, except for human subtelomeric repeats. CONCLUSION: Our attempt to elucidate the differences in the epigenetic regulatory mechanisms between birds and mammals explored the evidence that they share a common chromatin-based regulation of TET-DNA access, while chicken DNMT1 is involved in different target sequence recognition systems, suggesting that factors inducing DNMT-DNA association have already diverged.
BACKGROUND: DNA methylation is a significant epigenetic modification that is evolutionarily conserved in various species and often serves as a repressive mark for transcription. DNA methylation levels and patterns are regulated by a balance of opposing enzyme functions, DNA methyltransferases, DNMT1/3A/3B and methylcytosine dioxygenases, TET1/2/3. In mice, the TET enzyme converts DNA cytosine methylation (5mC) to 5-hydroxymethylcytosine (5hmC) at the beginning of fertilisation and gastrulation and initiates a global loss of 5mC, while the 5mC level is increased on the onset of cell differentiation during early embryonic development. OBJECTIVE: Global loss and gain of DNA methylation may be differently regulated in diverged species. METHODS: Chicken B-cell lymphoma DT40 cells were used as an avian model to compare differences in the overall regulation of DNA modification with mammals. RESULTS: We found that DNA methylation is maintained at high levels in DT40 cells through compact chromatin formation, which inhibits TET-mediated demethylation. Human and mouse chromosomes introduced into DT40 cells by cell fusion lost the majority of 5mC, except for human subtelomeric repeats. CONCLUSION: Our attempt to elucidate the differences in the epigenetic regulatory mechanisms between birds and mammals explored the evidence that they share a common chromatin-based regulation of TET-DNA access, while chicken DNMT1 is involved in different target sequence recognition systems, suggesting that factors inducing DNMT-DNA association have already diverged.
Entities:
Keywords:
Chicken; DNA methylation; Divergence; Mammalian chromosome
Authors: Antoine H F M Peters; Stefan Kubicek; Karl Mechtler; Roderick J O'Sullivan; Alwin A H A Derijck; Laura Perez-Burgos; Alexander Kohlmaier; Susanne Opravil; Makoto Tachibana; Yoichi Shinkai; Joost H A Martens; Thomas Jenuwein Journal: Mol Cell Date: 2003-12 Impact factor: 17.970