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  • 1
    Publication Date: 2013-07-03
    Description: DNA methylation is a heritable epigenetic modification involved in gene silencing, imprinting, and the suppression of retrotransposons. Global DNA demethylation occurs in the early embryo and the germ line, and may be mediated by Tet (ten eleven translocation) enzymes, which convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC). Tet enzymes have been studied extensively in mouse embryonic stem (ES) cells, which are generally cultured in the absence of vitamin C, a potential cofactor for Fe(II) 2-oxoglutarate dioxygenase enzymes such as Tet enzymes. Here we report that addition of vitamin C to mouse ES cells promotes Tet activity, leading to a rapid and global increase in 5hmC. This is followed by DNA demethylation of many gene promoters and upregulation of demethylated germline genes. Tet1 binding is enriched near the transcription start site of genes affected by vitamin C treatment. Importantly, vitamin C, but not other antioxidants, enhances the activity of recombinant Tet1 in a biochemical assay, and the vitamin-C-induced changes in 5hmC and 5mC are entirely suppressed in Tet1 and Tet2 double knockout ES cells. Vitamin C has a stronger effect on regions that gain methylation in cultured ES cells compared to blastocysts, and in vivo are methylated only after implantation. In contrast, imprinted regions and intracisternal A particle retroelements, which are resistant to demethylation in the early embryo, are resistant to vitamin-C-induced DNA demethylation. Collectively, the results of this study establish vitamin C as a direct regulator of Tet activity and DNA methylation fidelity in ES cells.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3893718/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3893718/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Blaschke, Kathryn -- Ebata, Kevin T -- Karimi, Mohammad M -- Zepeda-Martinez, Jorge A -- Goyal, Preeti -- Mahapatra, Sahasransu -- Tam, Angela -- Laird, Diana J -- Hirst, Martin -- Rao, Anjana -- Lorincz, Matthew C -- Ramalho-Santos, Miguel -- 92093/Canadian Institutes of Health Research/Canada -- CA151535/CA/NCI NIH HHS/ -- DP2 OD007420/OD/NIH HHS/ -- DP2OD004698/OD/NIH HHS/ -- HD065812/HD/NICHD NIH HHS/ -- P30 DK063720/DK/NIDDK NIH HHS/ -- R01 AI044432/AI/NIAID NIH HHS/ -- R01 CA151535/CA/NCI NIH HHS/ -- R01 HD065812/HD/NICHD NIH HHS/ -- R01 OD012204/OD/NIH HHS/ -- England -- Nature. 2013 Aug 8;500(7461):222-6. doi: 10.1038/nature12362. Epub 2013 Jun 30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Obstetrics and Gynecology and Center for Reproductive Sciences, University of California San Francisco, San Francisco, California 94143, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23812591" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antioxidants/pharmacology ; Ascorbic Acid/*pharmacology ; Blastocyst/metabolism ; Cell Line ; Culture Media/chemistry ; Cytosine/analogs & derivatives/metabolism ; DNA Methylation/*drug effects ; DNA-Binding Proteins/genetics/*metabolism ; Embryonic Stem Cells/*drug effects/metabolism ; Gene Expression Regulation, Developmental/drug effects ; Gene Knockout Techniques ; Mice ; Protein Binding/drug effects ; Proto-Oncogene Proteins/genetics/*metabolism ; Recombinant Proteins/genetics/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2000-06-20
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 3
    Publication Date: 2012-12-20
    Description: KitL, via its receptor cKit, supports primordial germ cell (PGC) growth, survival, migration and reprogramming to pluripotent embryonic germ cells (EGCs). However, the signaling downstream of KitL and its regulation in PGCs remain unclear. A constitutively activating mutation, cKit V558 , causes gain-of-function phenotypes in mast cells and intestines, and gastrointestinal stromal tumors (GISTs) when heterozygous. Unexpectedly, we find that PGC growth is not significantly affected in cKit V558 heterozygotes, whereas in homozygotes, increased apoptosis and inefficient migration lead to the depletion of PGCs. Through genetic studies, we reveal that this oncogenic cKit allele exhibits loss-of-function behavior in PGCs distinct from that in GIST development. Examination of downstream signaling in GISTs from cKit V558/+ mice confirmed hyperphosphorylation of AKT and ERK, but both remain unperturbed in cKit V558/+ PGCs and EGCs. In contrast, we find reduced activation of ERK1/2 and JNK1 in cKit V558 homozygous PGCs and EGCs. Inhibiting JNK, though not ERK1/2, increased apoptosis of wild-type PGCs, but did not further affect the already elevated apoptosis of cKit V558 / V558 PGCs. These results demonstrate a cell-context-dependent response to the cKit V558 mutation. We propose that AKT overload protection and JNK-mediated survival comprise PGC-specific mechanisms for regulating cKit signaling.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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  • 4
    Publication Date: 2012-10-16
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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  • 5
    Publication Date: 2021-04-01
    Description: Meiosis is critical to generating oocytes and ensuring female fertility; however, the mechanisms regulating the switch from mitotic primordial germ cells to meiotic germ cells are poorly understood. Here, we implicate intercellular bridges (ICBs) in this state transition. We used three-dimensional in toto imaging to map meiotic initiation in the mouse fetal ovary and revealed a radial geometry of this transition that precedes the established anterior-posterior wave. Our studies reveal that appropriate timing of meiotic entry across the ovary and coordination of mitotic-meiotic transition within a cyst depend on the ICB component Tex14, which we show is required for functional cytoplasmic sharing. We find that Tex14 mutants more rapidly attenuate the pluripotency transcript Dppa3 upon meiotic initiation, and Dppa3 mutants undergo premature meiosis similar to Tex14. Together, these results lead to a model that ICBs coordinate and buffer the transition from pluripotency to meiosis through dilution of regulatory factors.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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