近日z在線翻譯，PLoS Genetics雜志在線發(fā)表了中國科學(xué)院上海植物逆境生物學(xué)研究中心朱健康研究組題為“The SnRK2 kinases modulate miRNA accumulation in Arabidopsis”的研究論文。該項(xiàng)研究揭示了植物ABA信號轉(zhuǎn)導(dǎo)和滲透脅迫的關(guān)鍵蛋白激酶SnRK2參與了miRNA生物合成的調(diào)控。
Fig. A novel function of SnRK2 protein kinases in regulation of miRNA biogenesis
microRNA（miRNA）是是一種廣泛存在于動植物體內(nèi)的長度為20-24個(gè)核苷酸的非編碼的小RNA。通過調(diào)控mRNA的剪切和翻譯z在線翻譯，miRNA參與了植物生長發(fā)育、脅迫應(yīng)答等許多生物學(xué)過程。III型核糖核酸酶DCL1、鋅指蛋白SE以及雙鏈RNA結(jié)合蛋白HYL1是miRNA合成復(fù)合體的核心組分。已知植物激素脫落酸和滲透脅迫應(yīng)答途徑能夠影響miRNA的積累，但詳細(xì)的分子機(jī)制并不清楚。
該研究團(tuán)隊(duì)發(fā)現(xiàn)植物激素脫落酸和滲透脅迫應(yīng)答途徑的核心組分SnRK2蛋白激酶能調(diào)控miRNA合成途徑中的核心組分，并調(diào)控miRNA的合成。在模式植物擬南芥中，SnRK2蛋白激酶家族共有10個(gè)成員（SnRK2.1-SnRK2.10）。其中，snrk2.2/2.3/2.6三突變體對ABA不敏感，而缺失所有SnRK2成員的snrk2十突變體缺乏適應(yīng)滲透脅迫的能力，對滲透脅迫敏感。發(fā)現(xiàn)snrk2.2/2.3/2.6突變體中，miR160等miRNA的含量降低，對應(yīng)的miRNA的前體（pri-miRNA）以及靶基因表達(dá)增加。在snrk2三突變體和十突變體中HYL1蛋白含量降低。進(jìn)一步的研究表明HYL1和SE蛋白可能是SnRK2蛋白激酶的磷酸化底物 。該研究發(fā)現(xiàn)了SnRK2蛋白激酶在miRNA合成過程中的重要作用，并初步揭示了ABA和滲透脅迫調(diào)控miRNA合成的分子機(jī)制。
miRNAs play critical roles in various biological processes. miRNA biogenesis in both animals and plants are generated by a miRNA processing complex. Studies on specific miRNA function in different biological process have been extensively reported. However, how miRNA biogenesis is modulated, especially by environmental stimuli is poorly understood. The family of 10 redundant members of SnRK2 protein kinases are the central components of abscisic acid (ABA) and osmotic stress signaling pathways. In this study, our work reveals a novel role for SnRK2s in the modulation of miRNA levels. Importantly, we show that the SnRK2 kinases are required for the maintenance of the steady state level of HYL1 protein and the miRNA processing complex components, SE and HYL1, are potential substrates of the SnRK2 kinases. Our study provides a new mechanism of regulation of miRNA biogenesis and paves the way for further understanding of the impact of ABA and osmotic stress signaling on miRNA production.
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