Gemline development regulation by maternally localized factor PEM

早期胚胎生殖系细胞合子转录的抑制与其从体细胞谱系中分离紧密相关。许多无脊椎动物胚胎利用由生殖系细胞连续遗传的局部母体因子来沉默生殖系。胚系静止也与RNA聚合酶II的Ser 2磷酸化不足有关。使用海鞘Halocynthia roretzi，我们确定了第一个后口的例子，母系本地化的因素，PEM，通过Ser 2磷酸化不足抑制生殖系转录。我们的研究结果表明，果蝇的非同源蛋白PEM、Pgc和C. elegans通过类似的功能抑制生殖系基因表达：通过与P-TEFb复合物（一种磷酸化Ser 2的激酶）结合，保持Ser 2磷酸化不足。目前的研究提供了一个有趣的例子，进化的限制，如何生殖沉默的机制可以在不同的动物进化。

Suppression of zygotic transcription in early embryonic germline cells is tightly linked to its separation from the somatic lineage. Many invertebrate embryos utilize localized maternal factors that are successively inherited by the germline cells for silencing the germline. Germline quiescence has also been associated with the underphosphorylation of Ser2 of RNA polymerase II. Using an ascidian Halocynthia roretzi, we identified a first deuterostome example of a maternally localized factor, PEM, which represses germline transcription through Ser2 underphosphorylation. Our results suggest that non-homologous proteins, PEM, Pgc of Drosophila, and PIE-1 of C. elegans, repress germline gene expression through analogous functions: by keeping Ser2 underphosphorylated through binding to the P-TEFb complex, a kinase that phosphorylates Ser2. The present study provides an interesting example of evolutionary constraint on how a mechanism of germline silencing can evolve in diverse animals.