Nishida Kazumichi M, Saito Kuniaki, Mori Tomoko, Kawamura Yoshinori, Nagami-Okada Tomoko, Inagaki Sachi, Siomi Haruhiko, Siomi Mikiko C
Institute for Genome Research, University of Tokushima, Tokushima, Japan.
RNA. 2007 Nov;13(11):1911-22. doi: 10.1261/rna.744307. Epub 2007 Sep 13.
Genetic studies have shown that Aubergine (Aub), one of the Piwi subfamily of Argonautes in Drosophila, is essential for germ cell formation and maintaining fertility. aub mutations lead to the accumulation of retrotransposons in ovaries and testes, and Stellate transcripts in testes. Aub in ovaries associates with a variety of Piwi-interacting RNAs (piRNAs) derived from repetitive intergenic elements including retrotransposons. Here we found that Aub in testes also associates with various kinds of piRNAs. Although in ovaries Aub-associated piRNA populations are quite diverse, piRNAs with Aub in testes show a strong bias. The most abundant piRNAs were those corresponding to antisense transcripts of Suppressor of Stellate [Su(Ste)] genes known to be involved in Stellate gene silencing. The second most abundant class was made up of those from chromosome X and showed strong complementarity to vasa transcripts. Immunopurified Aub-piRNA complexes from testes displayed activity in cleaving target RNA containing sequences complementary to Stellate and vasa transcripts. These results provide the first biochemical insights into gene silencing mechanisms mediated by Aub and piRNAs in fly testes.
遗传学研究表明，茄子（Aub）是果蝇中Argonaute蛋白家族Piwi亚家族的一员，对生殖细胞形成和维持生育能力至关重要。aub突变会导致反转录转座子在卵巢和睾丸中积累，以及睾丸中Stellate转录本的积累。卵巢中的Aub与多种源自包括反转录转座子在内的重复基因间元件的Piwi相互作用RNA（piRNA）相关联。在此，我们发现睾丸中的Aub也与多种piRNA相关联。尽管卵巢中与Aub相关的piRNA群体相当多样，但睾丸中与Aub相关的piRNA表现出强烈的偏向性。最丰富的piRNA是那些与已知参与Stellate基因沉默的Stellate抑制因子[Su(Ste)]基因的反义转录本相对应的piRNA。第二丰富的类别由来自X染色体的piRNA组成，并且与vasa转录本具有很强的互补性。从睾丸中免疫纯化的Aub-piRNA复合物在切割含有与Stellate和vasa转录本互补序列的靶RNA时表现出活性。这些结果为果蝇睾丸中由Aub和piRNA介导的基因沉默机制提供了首个生化见解。
