Krimper Enforces an Antisense Bias on piRNA Pools by Binding AGO3 in the Drosophila Germline
Krimper Enforces an Antisense Bias on piRNA Pools by Binding AGO3 in the Drosophila Germline
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DOI：
10.1016/j.molcel.2015.06.024
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发表时间：
2015-08-20
期刊：
影响因子：
16
通讯作者：
Siomi, Haruhiko
中科院分区：
文献类型：
--
作者：
Sato, Kaoru;Iwasaki, Yuka W.;Siomi, Haruhiko
Piwi相互作用RNA（piRNA）抑制动物生殖细胞中的转座子活性。在果蝇卵巢中，初级Aubergine（Aub）结合的反义piRNA启动乒乓循环以产生次级AGO 3结合的正义piRNA。这增加了二级Aub结合的反义piRNA的数量，这些piRNA可以破坏转座子mRNA。在这里，我们表明，Krimper（Krimp），都铎结构域蛋白，直接与piRNA的自由AGO 3相互作用，以促进对称二甲基精氨酸（sDMA）的修饰，确保正义piRNA加载到sDMA修饰的AGO 3。在aub突变卵巢中，AGO 3与乒乓签名piRNA缔合，表明AGO 3与初级皮尔纳加载的相容性。在培养的卵巢体细胞（OSC）中，Krimp螯合在Krimp体内异位表达的AGO 3，其中仅初级皮尔纳途径起作用。在OSC中的krimp-RNAi后，AGO 3负载piRNA，进一步显示AGO 3用于初级皮尔纳负载的能力。我们提出Krimp通过结合AGO 3并阻断其与初级piRNA的接触来对皮尔纳池实施反义偏好。
Piwi-interacting RNAs (piRNAs) suppress transposon activity in animal germ cells. In the Drosophila ovary, primary Aubergine (Aub)-bound antisense piRNAs initiate the ping-pong cycle to produce secondary AGO3-bound sense piRNAs. This increases the number of secondary Aub-bound antisense piRNAs that can act to destroy transposon mRNAs. Here we show that Krimper (Krimp), a Tudor-domain protein, directly interacts with piRNA-free AGO3 to promote symmetrical dimethylarginine (sDMA) modification, ensuring sense piRNA-loading onto sDMA-modified AGO3. In aub mutant ovaries, AGO3 associates with ping-pong signature piRNAs, suggesting AGO3's compatibility with primary piRNA loading. Krimp sequesters ectopically expressed AGO3 within Krimp bodies in cultured ovarian somatic cells (OSCs), in which only the primary piRNA pathway operates. Upon krimp-RNAi in OSCs, AGO3 loads with piRNAs, further showing the capacity of AGO3 for primary piRNA loading. We propose that Krimp enforces an antisense bias on piRNA pools by binding AGO3 and blocking its access to primary piRNAs.