Nature：可防止原始生殖细胞变成体细胞的蛋白质
生物谷报道：日本研究人员日前报告说，他们通过实验证实，动物肌体内存在的一种蛋白质可防止原始生殖细胞误变成体细胞。
生殖细胞是诞生新生命的源泉，如果原始生殖细胞中途分化成体细胞而消失，物种将难以繁衍。日本理化研究所中村辉等研究人员在１6日的英国《自然》杂志网络版上发表论文说，正常情况下，动物肌体内一种叫做“Ｐｇｃ”的蛋白质可以和酶“Ｐ－ＴＥＦｂ”结合，通过基因作用，抑制原始生殖细胞分化成体细胞。
在实验中，研究人员让果蝇体内的“Ｐｇｃ”不发挥作用，之后，受精卵虽然能发育成成虫，但是这种成虫不能生育后代。研究人员推断这是因为原始生殖细胞在分化阶段变成了体细胞，导致成虫没有生殖细胞而不能生育。（新华网）
生物谷推荐原始出处：
Nature advance online publication 16 January 2008 | doi:10.1038/nature06498; Received 11 July 2007; Accepted 26 November 2007; Published online 16 January 2008
Drosophila Pgc protein inhibits P-TEFb recruitment to chromatin in primordial germ cells
Kazuko Hanyu-Nakamura1,3, Hiroko Sonobe-Nojima1,3, Akie Tanigawa1, Paul Lasko2 & Akira Nakamura1
- Laboratory for Germline Development, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
- Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada
- These authors contributed equally to this work.
Correspondence to: Akira Nakamura1 Correspondence and requests for materials should be addressed to A.N. (Email: akiran@cdb.riken.jp).
Germ cells are the only cells that transmit genetic information to the next generation, and they therefore must be prevented from differentiating inappropriately into somatic cells1. A common mechanism by which germline progenitors are protected from differentiation-inducing signals is a transient and global repression of RNA polymerase II (RNAPII)-dependent transcription1. In both Drosophila and Caenorhabditis elegans embryos, the repression of messenger RNA transcription during germ cell specification correlates with an absence of phosphorylation of Ser 2 residues in the carboxy-terminal domain of RNAPII (hereafter called CTD)2, a critical modification for transcriptional elongation3. Here we show that, in Drosophila embryos, a small protein encoded by polar granule component (pgc) is essential for repressing CTD Ser 2 phosphorylation in newly formed pole cells, the germline progenitors. Ectopic Pgc expression in somatic cells is sufficient to repress CTD Ser 2 phosphorylation. Furthermore, Pgc interacts, physically and genetically, with positive transcription elongation factor b (P-TEFb), the CTD Ser 2 kinase complex, and prevents its recruitment to transcription sites. These results indicate that Pgc is a cell-type-specific P-TEFb inhibitor that has a fundamental role in Drosophila germ cell specification. In C. elegans embryos, PIE-1 protein segregates to germline blastomeres, and is thought to repress mRNA transcription through interaction with P-TEFb4, 5, 6, 7. Thus, inhibition of P-TEFb is probably a common mechanism during germ cell specification in the disparate organisms C. elegans and Drosophila.
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