Maintenance of self-renewal ability of mouse embryonic stem cells in the absence of DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b.
DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b cooperatively regulate cytosine methylation in CpG dinucleotides in mammalian genomes, providing an epigenetic basis for gene silencing and maintenance of genome integrity. Proper CpG methylation is required for the normal growth of various somatic cell types, indicating its essential role in the basic cellular function of mammalian cells. Previous studies using Dnmt1(-/-) or Dnmt3a(-/-)Dnmt3b(-/-) ES cells, however, have shown that undifferentiated embryonic stem (ES) cells can tolerate hypomethylation for their proliferation. In an attempt to investigate the effects of the complete loss of CpG DNA methyltransferase function, we established mouse ES cells lacking all three of these enzymes by gene targeting. Despite the absence of CpG methylation, as demonstrated by genome-wide methylation analysis, these triple knockout (TKO) ES cells grew robustly and maintained their undifferentiated characteristics. TKO ES cells retained pericentromeric heterochromatin domains marked with methylation at Lys9 of histone H3 and heterochromatin protein-1, and maintained their normal chromosome numbers. Our results indicate that ES cells can maintain stem cell properties and chromosomal stability in the absence of CpG methylation and CpG DNA methyltransferases.
Tsumura
Akiko
A
Laboratory for Mammalian Epigenetic Studies, Center for Developmental Biology, RIKEN, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan.
Hayakawa
Tomohiro
T
Kumaki
Yuichi
Y
Takebayashi
Shin-ichiro
S
Sakaue
Morito
M
Matsuoka
Chisa
C
Shimotohno
Kunitada
K
Ishikawa
Fuyuki
F
Li
En
E
Ueda
Hiroki R
HR
Nakayama
Jun-ichi
J
Okano
Masaki
M
D000595:Amino Acid Sequence; D000818:Animals; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D000090205:DNA Methyltransferase 3A; D015257:DNA-Cytosine Methylases / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D000097584:DNA Methyltransferase 3B
D002843:Chromatin; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D015257:DNA-Cytosine Methylases; D000097584:DNA Methyltransferase 3B; C000715535:Dnmt3a protein, mouse; C081573:DNA modification methylase SssI; C000619381:Dnmt1 protein, mouse