A regulatory circuit for piwi by the large Maf gene traffic jam in Drosophila
A regulatory circuit for piwi by the large Maf gene traffic jam in Drosophila
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DOI：
10.1038/nature08501
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发表时间：
2009-10-29
期刊：
影响因子：
64.8
通讯作者：
Siomi, Mikiko C.
中科院分区：
文献类型：
--
作者：
Saito, Kuniaki;Inagaki, Sachi;Siomi, Mikiko C.
PIWI相互作用RNA（piRNA）通过与PIWI蛋白Argonaute 3（AGO 3）、Aubergine（Aub）和Piwi（1，2）结合来沉默果蝇生殖系中的反转录转座子。果蝇中的piRNA由基因间重复基因和皮尔纳簇通过两个系统产生：初级加工途径和扩增环（1-7）。扩增环以Dicer非依赖性、PIWI-Slicer依赖性方式发生（3、4、8）。然而，初级皮尔纳加工仍然难以捉摸。在这里，我们分析了果蝇卵巢体细胞系中的皮尔纳加工，其中Piwi而不是Aub或AGO 3表达;因此，仅存在初级piRNA。除了弗拉门戈之外，Piwi特异性皮尔纳簇（3），交通堵塞（tj）（9），一个大的Maf基因，被确定为新的皮尔纳簇。由tj产生的piRNA对应于tj信使RNA的非翻译区，并且是有义定向的。皮尔纳加载到Piwi上可能发生在细胞质中。西葫芦（10）是一种编码推定细胞质核酸酶的基因，是tj衍生的皮尔纳产生所需的。在tj和piwi突变卵巢中，体细胞不能与生殖细胞混合，Fasciclin III过表达。tj的缺失废除了性腺体细胞中的Piwi表达。因此，在性腺体细胞中，tj同时产生两种不同的分子：激活Piwi表达的TJ蛋白和定义Piwi沉默靶点的piRNA。
PIWI-interacting RNAs (piRNAs) silence retrotransposons in Drosophila germ lines by associating with the PIWI proteins Argonaute 3 (AGO3), Aubergine (Aub) and Piwi(1,2). piRNAs in Drosophila are produced from intergenic repetitive genes and piRNA clusters by two systems: the primary processing pathway and the amplification loop(1-7). The amplification loop occurs in a Dicer-independent, PIWI-Slicer-dependent manner(3,4,8). However, primary piRNA processing remains elusive. Here we analysed piRNA processing in a Drosophila ovarian somatic cell line where Piwi, but not Aub or AGO3, is expressed; thus, only the primary piRNAs exist. In addition to flamenco, a Piwi-specific piRNA cluster(3), traffic jam (tj)(9), a large Maf gene, was determined as a new piRNA cluster. piRNAs arising from tj correspond to the untranslated regions of tj messenger RNA and are sense-oriented. piRNA loading on to Piwi may occur in the cytoplasm. zucchini(10), a gene encoding a putative cytoplasmic nuclease, is required for tj-derived piRNA production. In tj and piwi mutant ovaries, somatic cells fail to intermingle with germ cells and Fasciclin III is overexpressed. Loss of tj abolishes Piwi expression in gonadal somatic cells. Thus, in gonadal somatic cells, tj gives rise simultaneously to two different molecules: the TJ protein, which activates Piwi expression, and piRNAs, which define the Piwi targets for silencing.