Transcriptional repression and DNA hypermethylation of a small set of ES cell marker genes in male germline stem cells.
BACKGROUND
We previously identified a set of genes called ECATs (ES cell-associated transcripts) that are expressed at high levels in mouse ES cells. Here, we examine the expression and DNA methylation of ECATs in somatic cells and germ cells.


RESULTS
In all ECATs examined, the promoter region had low methylation levels in ES cells, but higher levels in somatic cells. In contrast, in spite of their lack of pluripotency, male germline stem (GS) cells expressed most ECATs and exhibited hypomethylation of ECAT promoter regions. We observed a similar hypomethylation of ECAT loci in adult testis and isolated sperm. Some ECATs were even less methylated in male germ cells than in ES cells. However, a few ECATs were not expressed in GS cells, and most of them targets of Oct3/4 and Sox2. The Octamer/Sox regulatory elements were hypermethylated in these genes. In addition, we found that GS cells express little Sox2 protein and low Oct3/4 protein despite abundant expression of their transcripts.


CONCLUSIONS
Our results suggest that DNA hypermethylation and transcriptional repression of a small set of ECATs, together with post-transcriptional repression of Oct3/4 and Sox2, contribute to the loss of pluripotency in male germ cells.
Imamura
Masanori
M
Department of Stem Cell Biology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan. imamura@frontier.kyoto-u.ac.jp
Miura
Kyoko
K
Iwabuchi
Kumiko
K
Ichisaka
Tomoko
T
Nakagawa
Masato
M
Lee
Jiyoung
J
Kanatsu-Shinohara
Mito
M
Shinohara
Takashi
T
Yamanaka
Shinya
S
D000818:Animals; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D033481:Chromosomes, Mammalian / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D051519:Fibroblast Growth Factor 4 / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D005819:Genetic Markers / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D027701:Organic Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D055748:SOXB1 Transcription Factors; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*; D000099254:Organic Cation Transporter 3
D004247:DNA; D004268:DNA-Binding Proteins; D051519:Fibroblast Growth Factor 4; D005819:Genetic Markers; D018398:Homeodomain Proteins; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; D027701:Organic Cation Transport Proteins; D055748:SOXB1 Transcription Factors; D015534:Trans-Activators; D000099254:Organic Cation Transporter 3; C496446:Fgf4 protein, mouse; C475540:Nanog protein, mouse; C494174:Pou5f1 protein, mouse; C527783:Sox2 protein, mouse