Ci-Pem-1 localizes to the nucleus and represses somatic gene transcription in the germline of Ciona intestinalis embryos
Ci-Pem-1 localizes to the nucleus and represses somatic gene transcription in the germline of Ciona intestinalis embryos
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DOI：
10.1242/dev.058131
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发表时间：
2011-07-15
期刊：
影响因子：
4.6
通讯作者：
Nakamura, Akira
中科院分区：
文献类型：
--
作者：
Shirae-Kurabayashi, Maki;Matsuda, Kazuki;Nakamura, Akira
在许多动物胚胎中，生殖细胞的形成取决于位于种质中的母体因素。为了确保生殖细胞的发育，必须防止生殖系祖细胞不适当地分化成体细胞。一个共同的机制，这似乎是主动抑制体细胞基因转录。种特异性的种质组分，如果蝇的Pgc和C. elegans，通过抑制一般的转录机制来建立种系转录静止。在海鞘中，尽管已经提出了生殖系中的转录抑制，但所涉及的因素和机制尚不清楚。我们发现，Ci-pem-1 RNA，这是一个海鞘特异性成分的postplasm（相当于海鞘的种质），定位于生殖细胞分裂球的细胞核，以及postplasm的蛋白质产品。吗啉代谷胱甘肽介导的Ci-pem-1敲低导致了几个体细胞基因的异位表达，这些基因通常在种系中是沉默的。在Ci-Pem-1敲低胚胎中，β-连环蛋白和GATAa依赖性基因的表达在生殖系卵裂球中被去抑制，表明Ci-Pem-1广泛抑制生殖系mRNA转录。免疫沉淀实验表明，Ci-Pem-1能与两种C. Groucho的同源基因，它是mRNA转录的一般共阻遏物。这些结果表明Ci-pem-1是C.在生殖细胞命运的特化过程中，其蛋白质产物抑制体细胞基因的转录的种质RNA的转录形式，并且这种抑制可能通过Ci-Pem-1和Groucho共阻遏物之间的相互作用来操作。
In many animal embryos, germ-cell formation depends on maternal factors located in the germ plasm. To ensure the development of germ cells, germline progenitors must be prevented from differentiating inappropriately into somatic cells. A common mechanism for this appears to be the active repression of somatic gene transcription. Species-specific germ-plasm components, such as Pgc in Drosophila and PIE-1 in C. elegans, establish germline transcriptional quiescence by inhibiting general transcriptional machineries. In the ascidian Ciona intestinalis, although transcriptional repression in the germline has been proposed, the factors and mechanisms involved have been unknown. We found that the protein products of Ci-pem-1 RNA, which is an ascidian-specific component of the postplasm (the germ plasm equivalent in ascidians), localized to the nucleus of germline blastomeres, as well as to the postplasm. Morpholino oligonucleotide-mediated Ci-pem-1 knockdown resulted in the ectopic expression of several somatic genes that are usually silent in the germline. In the Ci-pem-1 knockdown embryos, the expression of both beta-catenin- and GATAa-dependent genes was derepressed in the germline blastomeres, suggesting that Ci-Pem-1 broadly represses germline mRNA transcription. Immunoprecipitation assays showed that Ci-Pem-1 could interact with two C. intestinalis homologs of Groucho, which is a general co-repressor of mRNA transcription. These results suggest that Ci-pem-1 is the C. intestinalis version of a germ-plasm RNA whose protein product represses the transcription of somatic genes during specification of the germ-cell fate, and that this repression may be operated through interactions between Ci-Pem-1 and Groucho co-repressors.