RT Journal
A1 Ichiyanagi, Kenji
A1 Li, Yungfeng
A1 Watanabe, Toshiaki
A1 Ichiyanagi, Tomoko
A1 Fukuda, Kei
A1 Kitayama, Junko
A1 Yamamoto, Yasuhiro
A1 Kuramochi-Miyagawa, Satomi
A1 Nakano, Toru
A1 Yabuta, Yukihiro
A1 Seki, Yoshiyuki
A1 Saitou, Mitinori
A1 Sasaki, Hiroyuki
T1 Locus- and domain-dependent control of DNA methylation at mouse B1 retrotransposons during male germ cell development
JF Genome Research 
JO Genome Research 
YR 2011 
FD December 01 
VO 21 
IS 12 
SP 2058 
OP 2066 
DO 10.1101/gr.123679.111 
UL http://genome.cshlp.org/content/21/12/2058.abstract 
AB In mammals, germ cells undergo striking dynamic changes in DNA methylation during their development. However, the dynamics and mode of methylation are poorly understood for short interspersed elements (SINEs) dispersed throughout the genome. We investigated the DNA methylation status of mouse B1 SINEs in male germ cells at different developmental stages. B1 elements showed a large locus-to-locus variation in methylation; loci close to RNA polymerase II promoters were hypomethylated, while most others were hypermethylated. Interestingly, a mutation that eliminates Piwi-interacting RNAs (piRNAs), which are involved in methylation of long interspersed elements (LINEs), did not affect the level of B1 methylation, implying a piRNA-independent mechanism. Methylation at B1 loci in SINE-poor genomic domains showed a higher dependency on the de novo DNA methyltransferase DNMT3A but not on DNMT3B, suggesting that DNMT3A plays a major role in methylation of these domains. We also found that many genes specifically expressed in the testis possess B1 elements in their promoters, suggesting the involvement of B1 methylation in transcriptional regulation. Taken altogether, our results not only reveal the dynamics and mode of SINE methylation but also suggest how the DNA methylation profile is created in the germline by a pair of DNA methyltransferases.