2009年11月10日,，北京生命科學(xué)研究所戚益軍實(shí)驗(yàn)室在The Plant Cell雜志在線發(fā)表題為“水稻microRNA的效應(yīng)復(fù)合體和靶標(biāo)”的研究論文。該論文報(bào)道了水稻中microRNA (miRNA)效應(yīng)復(fù)合體的生化特性,，并在基因組水平系統(tǒng)分析了受miRNA調(diào)控的靶標(biāo)基因,。
miRNAs是一類在真核生物中廣泛存在的，可以調(diào)控靶標(biāo)基因表達(dá)的非編碼RNAs,。miRNAs通過與Argonaute蛋白結(jié)合后形成基因沉默效應(yīng)復(fù)合體,，切割靶標(biāo)mRNA或抑制其翻譯。水稻(Orzya_sativa)編碼四個(gè)Argonaute1同源基因(AGO1a, AGO1b, AGO1c, and AGO1d),。戚益軍實(shí)驗(yàn)室利用RNAi方法同時(shí)敲除了水稻的四個(gè)AGO1基因,，發(fā)現(xiàn)轉(zhuǎn)基因植株具有復(fù)雜的發(fā)育表型，并且許多miRNAs的靶標(biāo)基因表達(dá)量上升,。作者純化了其中三個(gè)AGO1復(fù)合體，AGO1a,，AGO1b,，和AGO1c,。研究發(fā)現(xiàn)這三個(gè)AGO1蛋白都具有切割mRNA的活性，并且它們都對(duì)U 起始的小分子RNA具有偏好性,。作者進(jìn)一步克隆了與AGO1結(jié)合的小分子RNAs并進(jìn)行高通量測(cè)序,，發(fā)現(xiàn)AGO1s主要結(jié)合已知的miRNAs，而且大部分miRNAs均勻地分配到每一個(gè)AGO1中,，表明這些AGO1s具有功能上的冗余性,。同時(shí)，該研究還發(fā)現(xiàn)了一部分miRNAs只進(jìn)入其中某一個(gè)或某兩個(gè)AGO1蛋白,，說明這些AGO1s在功能上也具有一定的特異性,。本研究還對(duì)水稻MiRNAs的標(biāo)靶基因進(jìn)行了全基因組水平的分析和驗(yàn)證，發(fā)現(xiàn)這些目標(biāo)靶基因編碼包括參與重要發(fā)育的轉(zhuǎn)錄因子和參與其它各種生理過程的蛋白,，揭示了miRNAs在水稻生長發(fā)育過程中發(fā)揮著非常重要而廣泛的作用,。
北京生命科學(xué)研究所博士研究生武亮，技術(shù)員張青青和周環(huán)宇為該文章的共同第一作者,，論文的其他作者還有倪方銳和鄔雪影,。戚益軍博士為本文的通訊作者。此項(xiàng)研究為科技部863計(jì)劃和北京市科委資助課題,，在北京生命科學(xué)研究所完成,。（生物谷Bioon.com）
相關(guān)研究：The Plant Journal：人工miRNA介導(dǎo)基因沉默
生物谷推薦原始出處：
Plant Cell November 10, 2009; 10.1105/tpc.109.070938
Rice MicroRNA Effector Complexes and Targets
Liang Wu 1, Qingqing Zhang 2, Huanyu Zhou 2, Fangrui Ni 2, Xueying Wu 2, and Yijun Qi 2*
1 National Institute of Biological Sciences, Beijing 102206, China; College of Life Sciences, Beijing Normal University, Beijing 100875, China
2 National Institute of Biological Sciences, Beijing 102206, China
MicroRNAs (miRNAs) are small silencing RNAs with regulatory roles in gene expression. miRNAs interact with Argonaute (AGO) proteins to form effector complexes that cleave target mRNAs or repress translation. Rice (Oryza sativa) encodes four AGO1 homologs (AGO1a, AGO1b, AGO1c, and AGO1d). We used RNA interference (RNAi) to knock down the four AGO1s. The RNAi lines displayed pleiotropic developmental phenotypes and had increased accumulation of miRNA targets. AGO1a, AGO1b, and AGO1c complexes were purified and further characterized. The three AGO1s all have a strong preference for binding small RNAs (sRNAs) with 5' U and have Slicer activity. We cataloged the sRNAs in each AGO1 complex by deep sequencing and found that all three AGO1s predominantly bound known miRNAs. Most of the miRNAs were evenly distributed in the three AGO1 complexes, suggesting a redundant role for the AGO1s. Intriguingly, a subset of miRNAs were specifically incorporated into or excluded from one of the AGO1s, suggesting functional specialization among the AGO1s. Furthermore, we identified rice miRNA targets at a global level. The validated targets include transcription factors that control major stages of development and also genes involved in a variety of physiological processes, indicating a broad regulatory role for miRNAs in rice.
