A Natural Variant of miR397 Mediates a Feedback Loop in Circadian Rhythm
A Natural Variant of miR397 Mediates a Feedback Loop in Circadian Rhythm
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miR397 的自然变体介导昼夜节律的反馈环
DOI：
10.1104/pp.19.00710
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发表时间：
2020-01-01
期刊：
影响因子：
7.4
通讯作者：
Chen, Yue-Qin
中科院分区：
文献类型：
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作者：
Feng, Yan-Zhao;Yu, Yang;Chen, Yue-Qin
微小核糖核酸（miRNA）是一类长度约21个核苷酸的小型非编码RNA，在众多生物学过程中发挥调控作用。在动物体内，与几乎所有生物的健康状况密切相关的生物钟的正常运行受miRNA调控。然而，截至目前，尚无关于miRNA在植物昼夜节律调控中作用的报道。在此，我们报告了拟南芥（Arabidopsis thaliana）中miR397的一个自然变异体，它能延长昼夜节律周期并控制开花时间。miR397在被子植物中高度保守，在拟南芥中有两个成员：miR397a和miR397b。但只有miR397b能显著延迟开花。我们的研究结果表明，miR397b通过靶向酪蛋白激酶II β3亚基（CKB3）来控制开花，进而调节生物钟相关蛋白1（CCA1）的昼夜节律周期。我们进一步证明，CCA1可直接结合到MIR397B的启动子上并抑制其表达，从而形成一个miR397b - CKB3 - CCA1昼夜节律调控反馈回路。进化分析显示，miR397b是拟南芥中一个新进化出的遗传变异体，miR397b的靶向模式可能在增强植物适应性方面发挥作用。我们的研究结果为植物中miRNA介导的昼夜节律调控提供了证据，并表明存在一个通过调节昼夜节律来调控植物开花的反馈回路。
MicroRNAs (miRNAs) are small noncoding RNAs of similar to 21 nt in length, which have regulatory roles in many biological processes. In animals, proper functioning of the circadian clock, which is closely linked to the fitness of almost all living organisms, is regulated by miRNAs. However, to date, there have been no reports of the roles of miRNA in regulation of the plant circadian rhythm. Here, we report a natural variant of miR397 that lengthens the circadian period and controls flowering time in Arabidopsis (Arabidopsis thaliana). Highly conserved among angiosperms, the miRNA miR397 has two members in Arabidopsis: miR397a and miR397b. However, only miR397b significantly delayed flowering. Our results suggest that miR397b controls flowering by targeting CASEIN KINASE II SUBUNIT BETA3 (CKB3), in turn modulating the circadian period of CIRCADIAN CLOCK ASSOCIATED1 (CCA1). We further demonstrated that CCA1 directly bound to the promoter of MIR397B and suppressed its expression, forming a miR397b-CKB3-CCA1 circadian regulation feedback circuit. Evolutionary analysis revealed that miR397b is a newly evolved genetic variant in Arabidopsis, and the miR397b targeting mode may have a role in enhancing plant fitness. Our results provide evidence for miRNA-mediated circadian regulation in plants and suggest the existence of a feedback loop to manipulate plant flowering through the regulation of circadian rhythm.