Kansal Shivani, Panwar Vaishali, Mutum Roseeta Devi, Raghuvanshi Saurabh
Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India.
Front Plant Sci. 2021 Oct 18;12:720009. doi: 10.3389/fpls.2021.720009. eCollection 2021.
MicroRNAs (miRNAs) are critical components of the multidimensional regulatory networks in eukaryotic systems. Given their diverse spectrum of function, it is apparent that the transcription, processing, and activity of the miRNAs themselves, is very dynamically regulated. One of the most important and universally implicated signaling molecules is [Ca]. It is known to regulate a plethora of developmental and metabolic processes in both plants and animals; however, its impact on the regulation of miRNA expression is relatively less explored. The current study employed a combination of internal and external calcium channel inhibitors to establishing that [Ca] signatures actively regulate miRNA expression in rice. Involvement of [Ca] in the regulation of miRNA expression was further confirmed by treatment with calcimycin, the calcium ionophore. Modulation of the cytosolic calcium levels was also found to regulate the drought-responsive expression as well as ABA-mediated response of miRNA genes in rice seedlings. The study further establishes the role of calmodulins and Calmodulin-binding Transcription Activators (CAMTAs) as important components of the signal transduction schema that regulates miRNA expression. Yeast one-hybrid assay established that OsCAMTA4 & 6 are involved in the transcriptional regulation of miR156a and miR167h. Thus, the study was able to establish that [Ca] is actively involved in regulating the expression of miRNA genes both under control and stress conditions.
微小RNA（miRNA）是真核生物系统中多维调控网络的关键组成部分。鉴于其功能的多样性，很明显miRNA自身的转录、加工和活性受到非常动态的调控。最重要且普遍涉及的信号分子之一是[Ca]。已知它在植物和动物中调节大量的发育和代谢过程；然而，其对miRNA表达调控的影响相对较少被探索。当前的研究采用了内部和外部钙通道抑制剂的组合来证实[Ca]信号积极调控水稻中的miRNA表达。用钙离子载体A23187处理进一步证实了[Ca]参与miRNA表达的调控。还发现调节细胞质钙水平可调控水稻幼苗中miRNA基因的干旱响应表达以及脱落酸介导的响应。该研究进一步确立了钙调蛋白和钙调蛋白结合转录激活因子（CAMTA）作为调节miRNA表达的信号转导模式的重要组成部分的作用。酵母单杂交试验表明，OsCAMTA4和6参与miR156a和miR167h的转录调控。因此，该研究能够证实[Ca]在对照和胁迫条件下都积极参与调控miRNA基因的表达。
