Small extrachromosomal circular DNAs, microDNA, produce short regulatory RNAs that suppress gene expression independent of canonical promoters
Small extrachromosomal circular DNAs, microDNA, produce short regulatory RNAs that suppress gene expression independent of canonical promoters
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DOI：
10.1093/nar/gkz155
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发表时间：
2019-05-21
影响因子：
14.9
通讯作者：
Dutta, Anindya
中科院分区：
文献类型：
--
作者：
Paulsen, Teressa;Shibata, Yoshiyuki;Dutta, Anindya
染色体外环状DNA（eccDNA）分子的兴趣最近有所增加，因为它们广泛存在于从酵母到人类的每个物种的正常细胞中，它们在癌细胞中的水平增加，并且它们与致癌基因和耐药基因重叠。然而，哺乳动物组织和细胞系中的大多数eccDNA（microDNA）太小而不能携带蛋白质编码基因。我们已经通过创建模仿已知microDNA序列的人工microDNA分子来测试microDNA的功能能力，并发现它们表达功能性小调控RNA，包括microRNA和新型si-like RNA。微DNA在体外和体内的转录不依赖于典型的启动子序列。携带miRNA基因的微DNA形成转录物，所述转录物通过内源性RNA干扰途径加工成成熟的miRNA分子，所述成熟的miRNA分子抑制荧光素酶报告基因以及miRNA的内源性mRNA靶。此外，含有外显子序列的微DNA通过形成新的si样RNA抑制微DNA所来源的内源基因。我们还发现，内源性microDNA与RNA聚合酶亚基POLR 2 H和POLR 3F相关。总之，这些结果表明，microDNA可以通过产生已知的和新的调节小RNA来调节基因表达。
Interest in extrachromosomal circular DNA (eccDNA) molecules has increased recently because of their widespread presence in normal cells across every species ranging from yeast to humans, their increased levels in cancer cells and their overlap with oncogenic and drug-resistant genes. However, the majority of eccDNA (microDNA) in mammalian tissues and cell lines are too small to carry protein coding genes. We have tested functional capabilities of microDNA by creating artificial microDNA molecules mimicking known microDNA sequences and have discovered that they express functional small regulatory RNA including microRNA and novel si-like RNA. MicroDNA are transcribed in vitro and in vivo independent of a canonical promoter sequence. MicroDNA that carry miRNA genes form transcripts that are processed by the endogenous RNA-interference pathway into mature miRNA molecules, which repress a luciferase reporter gene as well as endogenous mRNA targets of the miRNA. Further, microDNA that contain sequences of exons repress the endogenous gene from which the microDNA were derived through the formation of novel si-like RNA. We also show that endogenous microDNA associate with RNA polymerases subunits, POLR2H and POLR3F. Together, these results suggest that microDNA may modulate gene expression through the production of both known and novel regulatory small RNA.