Selective recruitment of mRNAs and miRNAs to polyribosomes in response to rhizobia infection in Medicago truncatula
Selective recruitment of mRNAs and miRNAs to polyribosomes in response to rhizobia infection in Medicago truncatula
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DOI：
10.1111/tpj.12033
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发表时间：
2013-01-01
期刊：
影响因子：
7.2
通讯作者：
Eugenia Zanetti, Maria
中科院分区：
文献类型：
--
作者：
Alberto Reynoso, Mauricio;Antonio Blanco, Flavio;Eugenia Zanetti, Maria
mRNA的翻译是一个关键的调控步骤，有助于在发育或适应环境过程中协调和调节真核基因的表达。mRNA的稳定性或可翻译性可以通过控制多种生物过程的小调节RNA（sRNA）的作用来调节。在低氮条件下，豆科植物与土壤细菌结合，并发育出一种专门用于固氮的新器官：根瘤。为了深入了解根瘤形成过程中mRNA的翻译调控，在与苜蓿中华根瘤菌共生相互作用期间，模式豆科植物蒺藜苜蓿根中的mRNA和sRNA与多核糖体的关联的特征。定量比较15个基因的稳态和多核糖体mRNA参与的转录本确定了一组轻微或没有变化的总细胞丰度显着上调的水平与多核糖体在响应根瘤菌。这一组包括编码受体的mRNA，如结节器官形成、细菌感染或两者所需的激酶，以及编码GRAS和NF-γ转录因子（TF）的转录本。对总RNA和多核糖体RNA样品中sRNA的定量分析显示，成熟的microRNA（miRNAs）与翻译机制相关，特别是miR 169和miR 172，其分别靶向NF-YA/HAP 2和AP 2 TF。在接种后，miR 169的水平在多核糖体复合物中显著降低，伴随着NF-YA/HAP 2蛋白的积累增加。这些结果表明，mRNA和miRNA都受到不同的招聘到多核糖体，并暴露在根瘤共生过程中的选择性mRNA翻译的重要性。
Translation of mRNAs is a key regulatory step that contributes to the coordination and modulation of eukaryotic gene expression during development or adaptation to the environment. mRNA stability or translatability can be regulated by the action of small regulatory RNAs (sRNAs), which control diverse biological processes. Under low nitrogen conditions, leguminous plants associate with soil bacteria and develop a new organ specialized in nitrogen fixation: the nodule. To gain insight into the translational regulation of mRNAs during nodule formation, the association of mRNAs and sRNAs to polysomes was characterized in roots of the model legume Medicago truncatula during the symbiotic interaction with Sinorhizobium meliloti. Quantitative comparison of steady-state and polysomal mRNAs for 15 genes involved in nodulation identified a group of transcripts with slight or no change in total cellular abundance that were significantly upregulated at the level of association with polysomes in response to rhizobia. This group included mRNAs encoding receptors like kinases required either for nodule organogenesis, bacterial infection or both, and transcripts encoding GRAS and NF-Y transcription factors (TFs). Quantitative analysis of sRNAs in total and polysomal RNA samples revealed that mature microRNAs (miRNAs) were associated with the translational machinery, notably, miR169 and miR172, which target the NF-YA/HAP2 and AP2 TFs, respectively. Upon inoculation, levels of miR169 pronouncedly decreased in polysomal complexes, concomitant with the increased accumulation of the NF-YA/HAP2 protein. These results indicate that both mRNAs and miRNAs are subject to differential recruitment to polysomes, and expose the importance of selective mRNA translation during root nodule symbiosis.