Requirements for multivalent Yb body assembly in transposon silencing in Drosophila
Requirements for multivalent Yb body assembly in transposon silencing in Drosophila
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DOI：
10.15252/embr.201947708
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发表时间：
2019-07-01
期刊：
影响因子：
7.7
通讯作者：
Siomi, Mikiko C.
中科院分区：
文献类型：
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作者：
Hirakata, Shigeki;Ishizu, Hirotsugu;Siomi, Mikiko C.
雌性不育 (1) Yb (Yb) 是 Yb 小体的主要组成部分，核周病灶被认为是果蝇卵巢体细胞 (OSC) 中 PIWI 相互作用 RNA (piRNA) 生物发生的位点。 Yb 由三个结构域组成：解旋酶 C 末端 (Hel-C)、RNA 解旋酶和扩展 Tudor (eTud) 结构域。我们之前表明 RNA 解旋酶结构域对于 Yb-RNA 相互作用、Yb 体形成和 piRNA 生物发生是必需的。在这里，我们研究了 Hel-C 和 eTud 的功能，并揭示了 Hel-C 致力于 Yb-Yb 同型相互作用，而 eTud 对于 Yb-RNA 关联是必需的，RNA 解旋酶结构域也是如此。所有这些结构域对于 Yb 体的形成和转座子抑制 piRNA 的产生都是不可或缺的。然而，引人注目的是，与转座子沉默无关的基因piRNA是在Yb体被分解的OSC中产生的。我们还揭示了 Yb 体是液体状多价缩合物，其组装依赖于 Yb-Yb 同型相互作用和 Yb 特别是与弗拉门戈 RNA 转录物的结合，弗拉门戈 RNA 转录物是转座子抑制 piRNA 的来源。关于 Yb 体组装和 Yb 体在转座子沉默中的生物学相关性的新见解已经出现。
Female sterile (1) Yb (Yb) is a primary component of Yb bodies, perinuclear foci considered to be the site of PIWI-interacting RNA (piRNA) biogenesis in Drosophila ovarian somatic cells (OSCs). Yb consists of three domains: Helicase C-terminal (Hel-C), RNA helicase, and extended Tudor (eTud) domains. We previously showed that the RNA helicase domain is necessary for Yb-RNA interaction, Yb body formation, and piRNA biogenesis. Here, we investigate the functions of Hel-C and eTud and reveal that Hel-C is dedicated to Yb-Yb homotypic interaction, while eTud is necessary for Yb-RNA association, as is the RNA helicase domain. All of these domains are indispensable for Yb body formation and transposon-repressing piRNA production. Strikingly, however, genic piRNAs unrelated to transposon silencing are produced in OSCs where Yb bodies are disassembled. We also reveal that Yb bodies are liquid-like multivalent condensates whose assembly depends on Yb-Yb homotypic interaction and Yb binding particularly with flamenco RNA transcripts, the source of transposon-repressing piRNAs. New insights into Yb body assembly and biological relevance of Yb bodies in transposon silencing have emerged.