記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1242/dev.194605

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1242/dev.196212

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ajhg.2019.11.011

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記述言語：英語  

DOI： 10.1242/dmm.040139

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1242/dev.169102

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1186/s13072-017-0133-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1101/gad.271353.115

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BioMed Central Ltd.  

Background: Previously, a role was demonstrated for transcription in the acquisition of DNA methylation at imprinted control regions in oocytes. Definition of the oocyte DNA methylome by whole genome approaches revealed that the majority of methylated CpG islands are intragenic and gene bodies are hypermethylated. Yet, the mechanisms by which transcription regulates DNA methylation in oocytes remain unclear. Here, we systematically test the link between transcription and the methylome. Results: We perform deep RNA-Seq and de novo transcriptome assembly at different stages of mouse oogenesis. This reveals thousands of novel non-annotated genes, as well as alternative promoters, for approximately 10 % of reference genes expressed in oocytes. In addition, a large fraction of novel promoters coincide with MaLR and ERVK transposable elements. Integration with our transcriptome assembly reveals that transcription correlates accurately with DNA methylation and accounts for approximately 85-90 % of the methylome. We generate a mouse model in which transcription across the Zac1/Plagl1 locus is abrogated in oocytes, resulting in failure of DNA methylation establishment at all CpGs of this locus. ChIP analysis in oocytes reveals H3K4me2 enrichment at the Zac1 imprinted control region when transcription is ablated, establishing a connection between transcription and chromatin remodeling at CpG islands by histone demethylases. Conclusions: By precisely defining the mouse oocyte transcriptome, this work not only highlights transcription as a cornerstone of DNA methylation establishment in female germ cells, but also provides an important resource for developmental biology research.

DOI： 10.1186/s13059-015-0769-z

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BIOMED CENTRAL LTD  

Background: In the male germline, neonatal prospermatogonia give rise to spermatogonia, which include stem cell population (undifferentiated spermatogonia) that supports continuous spermatogenesis in adults. Although the levels of DNA methyltransferases change dynamically in the neonatal and early postnatal male germ cells, detailed genome-wide DNA methylation profiles of these cells during the stem cell formation and differentiation have not been reported.
Results: To understand the regulation of spermatogonial stem cell formation and differentiation, we examined the DNA methylation and gene expression dynamics of male mouse germ cells at the critical stages: neonatal prospermatogonia, and early postntal (day 7) undifferentiated and differentiating spermatogonia. We found large partially methylated domains similar to those found in cancer cells and placenta in all these germ cells, and high levels of non-CG methylation and 5-hydroxymethylcytosines in neonatal prospermatogonia. Although the global CG methylation levels were stable in early postnatal male germ cells, and despite the reported scarcity of differential methylation in the adult spermatogonial stem cells, we identified many regions showing stage-specific differential methylation in and around genes important for stem cell function and spermatogenesis. These regions contained binding sites for specific transcription factors including the SOX family members.
Conclusions: Our findings show a distinctive and dynamic regulation of DNA methylation during spermatogonial stem cell formation and differentiation in the neonatal and early postnatal testes. Furthermore, we revealed a unique accumulation and distribution of non-CG methylation and 5hmC marks in neonatal prospermatogonia. These findings contrast with the reported scarcity of differential methylation in adult spermatogonial stem cell differentiation and represent a unique phase of male germ cell development.

DOI： 10.1186/s12864-015-1833-5

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担当区分：最終著者   記述言語：英語  

DOI： 10.1515/bmc-2014-0036

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：17  

Epigenetic modifications influence gene expression and chromatin remodeling. In embryonic pluripotent stem cells, these epigenetic modifications have been extensively characterized
by contrast, the epigenetic events of tissue-specific stem cells are poorly understood. Here, we define a new epigenetic shift that is crucial for differentiation of murine spermatogonia toward meiosis. We have exploited a property of incomplete cytokinesis, which causes male germ cells to form aligned chains of characteristic lengths, as they divide and differentiate. These chains revealed the stage of spermatogenesis, so the epigenetic differences of various stages could be characterized. Single, paired and medium chain-length spermatogonia not expressing Kit (a marker of differentiating spermatogonia) showed no expression of Dnmt3a2 and Dnmt3b (two de novo DNA methyltransferases)
they also lacked the transcriptionally repressive histone modification H3K9me2. By contrast, spermatogonia consisting of ~8-16 chained cells with Kit expression dramatically upregulated Dnmt3a2/3b expression and also displayed increased H3K9me2 modification. To explore the function of these epigenetic changes in spermatogonia in vivo, the DNA methylation machinery was destabilized by ectopic Dnmt3b expression or Np95 ablation. Forced Dnmt3b expression induced expression of Kit
whereas ablation of Np95, which is essential for maintaining DNA methylation, interfered with differentiation and viability only after spermatogonia become Kit positive. These data suggest that the epigenetic status of spermatogonia shifts dramatically during the Kit-negative to Kit-positive transition. This shift might serve as a switch that determines whether spermatogonia self-renew or differentiate. © 2013. Published by The Company of Biologists Ltd.

DOI： 10.1242/dev.094045

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担当区分：筆頭著者,　責任著者   記述言語：日本語  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Allele-specific methylation of the endogenous 1119 imprinting control region (ICR) is established in sperm. We previously showed that the paternal H19 ICR in yeast artificial chromosome (YAC) transgenic mice (TgM) was preferentially methylated in somatic cells, but not in germ cells, suggesting that differential methylation could be established after fertilization. In this report, we discovered small RNA molecules in growing oocytes, the nucleotide sequences of which mapped to the H19 ICR. To test if these small RNA sequences play a role in the establishment of differential methylation, we deleted the sequences from the H19 ICR DNA and generated YAC TgM. In somatic cells of these mice, methylation imprinting of the transgene was normally established. In addition, the mutant fragment was not methylated in sperm and eggs. These data demonstrate that sequences in the H19 ICR that correspond to the small RNA sequences are dispensable for methylation imprinting in YAC TgM. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.gene.2012.07.062

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担当区分：筆頭著者   記述言語：英語   出版者・発行元：NATURE PUBLISHING GROUP  

Genomic imprinting is an epigenetic gene-marking phenomenon that occurs in the germline, whereby genes are expressed from only one of the two parental copies in embryos and adults. Imprinting is essential for normal mammalian development and its disruption can cause various developmental defects and diseases. The process of imprinting in the germline involves DNA methylation of the imprint control regions (ICRs), and resulting parental-specific methylation imprints are maintained in the zygote and act as the marks controlling imprinted gene expression. Recent studies in mice have revealed new factors involved in imprint establishment during gametogenesis and maintenance during early development. Clinical studies have identified cases of imprinting disorders where involvement of factors shared by multiple ICRs for establishment or maintenance is suspected. These include Beckwith-Wiedemann syndrome, transient neonatal diabetes, Silver-Russell syndrome and others. More severe disruptions can lead to recurrent molar pregnancy, miscarriage or infertility. Imprinting defects may also occur during assisted reproductive technology or cell reprogramming. In this review, we summarize our current knowledge on the mechanisms of imprint establishment and maintenance, and discuss the relationship with various human disorders. Journal of Human Genetics (2012) 57, 84-91; doi:10.1038/jhg.2011.151; published online 12 January 2012

DOI： 10.1038/jhg.2011.151

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1387/ijdb.120152gk

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATURE PUBLISHING GROUP  

Elucidating how and to what extent CpG islands (CGIs) are methylated in germ cells is essential to understand genomic imprinting and epigenetic reprogramming(1-3). Here we present, to our knowledge, the first integrated epigenomic analysis of mammalian oocytes, identifying over a thousand CGIs methylated in mature oocytes. We show that these CGIs depend on DNMT3A and DNMT3L(4,5) but are not distinct at the sequence level, including in CpG periodicity(6). They are preferentially located within active transcription units and are relatively depleted in H3K4me3, supporting a general transcription-dependent mechanism of methylation. Very few methylated CGIs are fully protected from post-fertilization reprogramming but, notably, the majority show incomplete demethylation in embryonic day (E) 3.5 blastocysts. Our study shows that CGI methylation in gametes is not entirely related to genomic imprinting but is a strong factor in determining methylation status in preimplantation embryos, suggesting a need to reassess mechanisms of post-fertilization demethylation.

DOI： 10.1038/ng.864

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記述言語：英語   出版者・発行元：6031  

Genomic imprinting causes parental origin-specific monoallelic gene expression through differential DNA methylation established in the parental germ line. However, the mechanisms underlying how specific sequences are selectively methylated are not fully understood. We have found that the components of the PIWI-interacting RNA (piRNA) pathway are required for de novo methylation of the differentially methylated region (DMR) of the imprinted mouse Rasgrf1 locus, but not other paternally imprinted loci. A retrotransposon sequence within a noncoding RNA spanning the DMR was targeted by piRNAs generated from a different locus. A direct repeat in the DMR, which is required for the methylation and imprinting of Rasgrf1, served as a promoter for this RNA. We propose a model in which piRNAs and a target RNA direct the sequence-specific methylation of Rasgrf1.

DOI： 10.1126/science.1203919

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：COMPANY OF BIOLOGISTS LTD  

Mammalian imprinted genes are associated with differentially methylated regions (DMRs) that are CpG methylated on one of the two parental chromosomes. In mice, at least 21 DMRs acquire differential methylation in the germline and many of them act as imprint centres. We previously reported the physical extents of differential methylation at 15 DMRs in mouse embryos at 12.5 days postcoitum. To reveal the ontogeny of differential methylation, we determined and compared methylation patterns of the corresponding regions in sperm and oocytes. We found that the extent of the gametic DMRs differs significantly from that of the embryonic DMRs, especially in the case of paternal gametic DMRs. These results suggest that the gametic DMR sequences should be used to extract the features specifying methylation imprint establishment in the germline: from this analysis, we noted that the maternal gametic DMRs appear as unmethylated islands in male germ cells, which suggests a novel component in the mechanism of gamete-specific marking. Analysis of selected DMRs in blastocysts revealed dynamic changes in allelic methylation in early development, indicating that DMRs are not fully protected from the major epigenetic reprogramming events occurring during preimplantation development. Furthermore, we observed non-CpG methylation in oocytes, but not in sperm, which disappeared by the blastocyst stage. Non-CpG methylation was frequently found at maternally methylated DMRs as well as non-DMR regions, suggesting its prevalence in the oocyte genome. These results provide evidence for a unique methylation profile in oocytes and reveal the surprisingly dynamic nature of DMRs in the early embryo.

DOI： 10.1242/dev.061416

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担当区分：筆頭著者   記述言語：日本語  

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担当区分：最終著者   記述言語：日本語   出版者・発行元：公益社団法人日本薬学会  

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記述言語：英語   出版者・発行元：(公社)日本生化学会  

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）   出版者・発行元：CAMBRIDGE UNIV PRESS  

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記述言語：日本語  

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