Across Metazoa, Piwi proteins play a critical role in protecting the germline genome through piRNA-mediated repression of transposable elements. In vertebrates, activity of Piwi proteins and the piRNA pathway was thought to be gonad specific. Our results reveal the expression of Piwil1 in a vertebrate somatic cell type, the neural crest. Piwil1 is expressed at low levels throughout the chicken neural tube, peaking in neural crest cells just before the specification event that enables epithelial-to-mesenchymal transition (EMT) and migration into the periphery. Loss of Piwil1 impedes neural crest specification and emigration. Small RNA sequencing reveals somatic piRNAs with sequence signatures of an active ping-pong loop. RNA-seq and functional experiments identify the transposon-derived gene ERNI as Piwil1’s target in the neural crest. ERNI, in turn, suppresses Sox2 to precisely control the timing of neural crest specification and EMT. Our data provide mechanistic insight into a novel function of the piRNA pathway as a regulator of somatic development in a vertebrate species.

中文翻译：

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共同选择 piRNA 通路以调节神经嵴规范

在后生动物中，Piwi 蛋白通过 piRNA 介导的转座因子抑制在保护种系基因组方面发挥着关键作用。在脊椎动物中，Piwi 蛋白和 piRNA 通路的活性被认为是性腺特异性的。我们的研究结果揭示了 Piwil1 在脊椎动物体细胞类型神经嵴中的表达。Piwil1 在整个鸡神经管中以低水平表达，在使上皮-间质转化 (EMT) 和迁移到外周的规范事件之前，在神经嵴细胞中达到峰值。Piwil1 的缺失阻碍了神经嵴的规范和迁移。小 RNA 测序揭示了具有活跃乒乓环序列特征的体细胞 piRNA。RNA-seq 和功能实验将转座子衍生基因 ERNI 确定为 Piwil1 在神经嵴中的目标。厄尼，Sox2精确控制神经嵴规范和 EMT 的时间。我们的数据提供了对 piRNA 途径作为脊椎动物物种体细胞发育调节剂的新功能的机制洞察力。