Cytoplasmic Arabidopsis AGO7 accumulates in membrane-associated siRNA bodies and is required for ta-siRNA biogenesis
Cytoplasmic Arabidopsis AGO7 accumulates in membrane-associated siRNA bodies and is required for ta-siRNA biogenesis
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DOI：
10.1038/emboj.2012.20
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发表时间：
2012-04-04
期刊：
影响因子：
11.4
通讯作者：
Maizel, Alexis
中科院分区：
文献类型：
--
作者：
Jouannet, Virginie;Moreno, Ana Beatriz;Maizel, Alexis
从TAS 3前体形成反式作用小干扰RNA（ta-siRNA）是由AGO 7/miR 390复合物触发的，AGO 7/miR 390复合物引发TAS 3通过RNA依赖性RNA聚合酶RDR 6和SGS 3转化为双链RNA。这些ta-siRNA控制植物发育的几个方面。AGO 7切割的TAS 3前体向RDR 6/SGS 3的路由机制及其亚细胞组织尚不清楚。我们发现AGO 7与SGS 3和RDR 6一起在不同于P体的细胞质siRNA体中积累。siRNA体与膜相关的病毒蛋白共定位，并且在应激诱导的翻译抑制后对应激颗粒标志物呈阳性，这表明siRNA体是在翻译期间停滞的mRNA积累的膜相关位点。AGO 7与miR 390和SGS 3在膜中聚集，并且其靶向细胞核防止其在siRNA体中积累和ta-siRNA形成。因此，细胞质和膜siRNA体中需要AGO 7进行TAS 3加工，揭示了膜相关核糖核颗粒在植物中ta-siRNA生物发生和AGO作用中迄今未知的作用。The EMBO Journal（2012）31，1704-1713. doi：10.1038/daj.2012.20; 2012年2月10日在线发布
Formation of trans-acting small interfering RNAs (ta-siRNAs) from the TAS3 precursor is triggered by the AGO7/miR390 complex, which primes TAS3 for conversion into double-stranded RNA by the RNA-dependent RNA polymerase RDR6 and SGS3. These ta-siRNAs control several aspects of plant development. The mechanism routing AGO7-cleaved TAS3 precursor to RDR6/SGS3 and its subcellular organization are unknown. We show that AGO7 accumulates together with SGS3 and RDR6 in cytoplasmic siRNA bodies that are distinct from P-bodies. siRNA bodies colocalize with a membrane-associated viral protein and become positive for stress-granule markers upon stress-induced translational repression, this suggests that siRNA bodies are membrane-associated sites of accumulation of mRNA stalled during translation. AGO7 congregates with miR390 and SGS3 in membranes and its targeting to the nucleus prevents its accumulation in siRNA bodies and ta-siRNA formation. AGO7 is therefore required in the cytoplasm and membranous siRNA bodies for TAS3 processing, revealing a hitherto unknown role for membrane-associated ribonucleoparticles in ta-siRNA biogenesis and AGO action in plants. The EMBO Journal (2012) 31, 1704-1713. doi: 10.1038/emboj.2012.20; Published online 10 February 2012