School of Biomedical Sciences and Pharmacy, Faculty of Health and Hunter Medical Research Institute, University of Newcastle, Callaghan, NSW, Australia.
BMC Genomics. 2012 Oct 19;13:561. doi: 10.1186/1471-2164-13-561.
MicroRNA (miRNA) are small non-coding RNA molecules which function as nucleic acid-based specificity factors in the universal RNA binding complex known as the RNA induced silencing complex (RISC). In the canonical gene-silencing pathway, these activated RISC particles are associated with RNA decay and gene suppression, however, there is evidence to suggest that in some circumstances they may also stabilise their target RNA and even enhance translation. To further explore the role of miRNA in this context, we performed a genome-wide expression analysis to investigate the molecular consequences of bidirectional modulation of the disease-associated miRNAs miR-181b and miR-107 in multiple human cell lines.
This data was subjected to pathways analysis and correlated against miRNA targets predicted through seed region homology. This revealed a large number of both conserved and non-conserved miRNA target genes, a selection of which were functionally validated through reporter gene assays. Contrary to expectation we also identified a significant proportion of predicted target genes with both conserved and non-conserved recognition elements that were positively correlated with the modulated miRNA. Finally, a large proportion of miR-181b associated genes devoid of the corresponding miRNA recognition element, were enriched with binding motifs for the E2F1 transcription factor, which is encoded by a miR-181b target gene.
These findings suggest that miRNA regulate target genes directly through interactions with both conserved and non-conserved target recognition elements, and can lead to both a decrease and increase in transcript abundance. They also multiply their influence through interaction with transcription factor genes exemplified by the observed miR-181b/E2F1 relationship.
MicroRNA（miRNA）是一种小的非编码 RNA 分子，作为核酸特异性因子在 RNA 诱导沉默复合物（RISC）等通用 RNA 结合复合物中发挥作用。在经典的基因沉默途径中，这些激活的 RISC 颗粒与 RNA 降解和基因抑制相关联，但有证据表明，在某些情况下，它们也可能稳定其靶 RNA ，甚至增强翻译。为了进一步探索 miRNA 在这种情况下的作用，我们进行了全基因组表达分析，以研究在多种人类细胞系中对疾病相关 miRNA miR-181b 和 miR-107 进行双向调节的分子后果。
对该数据进行了通路分析，并与通过种子区域同源性预测的 miRNA 靶标进行了相关分析。这揭示了大量保守和非保守的 miRNA 靶基因，其中一些通过报告基因检测得到了功能验证。出乎意料的是，我们还发现了大量预测的靶基因，其保守和非保守的识别元件都与被调节的 miRNA 呈正相关。最后，大量缺乏相应 miRNA 识别元件的 miR-181b 相关基因富集了 E2F1 转录因子的结合基序，而 E2F1 是 miR-181b 的靶基因。
这些发现表明，miRNA 通过与保守和非保守的靶标识别元件的相互作用直接调节靶基因，并能导致转录物丰度的降低和增加。它们还通过与转录因子基因的相互作用来增加其影响，如观察到的 miR-181b/E2F1 关系。
