An epigenetic switch is crucial for spermatogonia to exit the undifferentiated state toward a Kit-positive identity
An epigenetic switch is crucial for spermatogonia to exit the undifferentiated state toward a Kit-positive identity
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DOI：
10.1242/dev.094045
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发表时间：
2013-09
期刊：
影响因子：
4.6
通讯作者：
Takayuki Shirakawa;Ruken Yaman-Deveci;Shin-ichi Tomizawa;Yoshito Kamizato;K. Nakajima;Hidetoshi Sone
中科院分区：
文献类型：
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作者：
Takayuki Shirakawa;Ruken Yaman-Deveci;Shin-ichi Tomizawa;Yoshito Kamizato;K. Nakajima;Hidetoshi Sone
表观遗传修饰影响基因表达和染色质重塑。在胚胎多能干细胞中，这些表观遗传修饰已被广泛表征;相比之下，组织特异性干细胞的表观遗传事件知之甚少。在这里，我们定义了一个新的表观遗传转变，是至关重要的小鼠精原细胞向减数分裂分化。我们已经利用了胞质分裂不完全的特性，这导致雄性生殖细胞在分裂和分化时形成特征长度的排列链。这些连锁反应揭示了精子发生的阶段，因此可以表征不同阶段的表观遗传差异。单个、成对和中等链长的精原细胞不表达Kit（分化精原细胞的标志物），Dnmt 3a 2和Dnmt 3b（两种从头DNA甲基转移酶）不表达;它们也缺乏转录抑制性组蛋白修饰H3 K9 me 2。相比之下，精原细胞组成的88 -16链细胞与试剂盒表达显着上调Dnmt 3a 2/3b的表达，也显示出增加的H3 K9 me 2修饰。为了探索这些表观遗传变化在体内精原细胞中的功能，通过异位Dnmt 3b表达或Np 95消融使DNA甲基化机制不稳定。强迫Dnmt 3b表达诱导表达试剂盒，而消融Np 95，这是必不可少的维持DNA甲基化，干扰分化和活力后，精原细胞成为试剂盒阳性。这些数据表明，精原细胞的表观遗传状态发生了显着变化，在试剂盒阴性到试剂盒阳性的过渡。这种转变可能是决定精原细胞自我更新或分化的一个开关。
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.