Degradation of unmethylated miRNA/miRNAs by a DEDDy-type 3' to 5' exoribonuclease Atrimmer 2 in Arabidopsis.
Degradation of unmethylated miRNA/miRNAs by a DEDDy-type 3' to 5' exoribonuclease Atrimmer 2 in Arabidopsis.
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拟南芥中 DEDDy 型 3' 至 5' 核糖核酸外切酶 Atrimmer 2 降解未甲基化的 miRNA/miRNA。
DOI：
10.1073/pnas.1721917115
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
Ren Guodong
中科院分区：
文献类型：
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作者：
Wang Xiaoyan;Wang Yuan;Dou Yongchao;Chen Lu;Wang Junli;Jiang Ning;Guo Chunce;Yao Qingqing;Wang Chizao;Liu Lin;Yu Bin;Zheng Binglian;Chekanova Julia A;Ma Jinbiao;Ren Guodong
HUA Enhancer 1（HEN 1）催化的3′端甲基化是植物小RNA稳定化的关键步骤，但未甲基化的小RNA是如何降解的仍不清楚。利用反向遗传学的方法，我们发现Atrimmer 2（ATRM 2），一种DEDDy型3′至5′核糖核酸外切酶，在拟南芥中降解未甲基化的miRNAs和miRNAs *s。ATRM 2中的功能丧失突变部分抑制了由HEN 1功能障碍引起的形态学缺陷，恢复了一部分miRNA的水平，并降低了相应miRNA靶点的表达。ATRM 2的功能障碍对miRNA修剪的影响可以忽略不计，并进一步增加hen 1 heso 1 urt 1的生育力，该突变体几乎完全消除了miRNA的尿苷化，表明ATRM 2可能既不参与3′至5′修剪，也不是特异性降解尿苷化miRNA的酶。值得注意的是，miRNAs及其相应的miRNAs *s的倍数变化在hen 1 atrm 2 versushen 1中显著相关。出乎意料的是，我们观察到一些miRNA* 的3′至5′修剪显著增加，但在ATRM 2受损背景中没有miRNA。这些数据表明ATRM 2对miRNA/miRNA* 双链体的作用，以及存在用于特异性修剪miRNA* 的未知核糖核酸外切酶。这种对miRNA/miRNA* 的不对称效应可能与Argonaute（AGO）蛋白有关，Argonaute（AGO）蛋白可以区分miRNA和miRNA*。最后，我们表明，ATRM 2共定位和物理相互作用的Argonaute 1（AGO 1）。综上所述，我们的研究结果表明，ATRM 2可能参与监视未甲基化的miRNA/miRNA* 双链体在RNA诱导的沉默复合物组装的起始步骤。
The 3′ end methylation catalyzed by HUA Enhancer 1 (HEN1) is a crucial step of small RNA stabilization in plants, yet how unmethylated small RNAs undergo degradation remains largely unknown. Using a reverse genetic approach, we here show that Atrimmer 2 (ATRM2), a DEDDy-type 3′ to 5′ exoribonuclease, acts in the degradation of unmethylated miRNAs and miRNA*s inArabidopsis. Loss-of-function mutations in ATRM2 partially suppress the morphological defects caused by HEN1 malfunction, with restored levels of a subset of miRNAs and receded expression of corresponding miRNA targets. Dysfunction of ATRM2 has negligible effect on miRNA trimming, and further increase the fertility ofhen1 heso1 urt1, a mutant with an almost complete abolishment of miRNA uridylation, indicating that ATRM2 may neither be involved in 3′ to 5′ trimming nor be the enzyme that specifically degrades uridylated miRNAs. Notably, the fold changes of miRNAs and their corresponding miRNA*s were significantly correlated inhen1 atrm2versushen1. Unexpectedly, we observed a marked increase of 3′ to 5′ trimming of several miRNA*s but not miRNAs in ATRM2 compromised backgrounds. These data suggest an action of ATRM2 on miRNA/miRNA* duplexes, and the existence of an unknown exoribonuclease for specific trimming of miRNA*. This asymmetric effect on miRNA/miRNA* is likely related to Argonaute (AGO) proteins, which can distinguish miRNAs from miRNA*s. Finally, we show that ATRM2 colocalizes and physically interacts with Argonaute 1 (AGO1). Taken together, our results suggest that ATRM2 may be involved in the surveillance of unmethylated miRNA/miRNA* duplexes during the initiation step of RNA-induced silencing complex assembly.