RNAi-dependent and independent control of LINE1 accumulation and mobility in mouse embryonic stem cells.
RNAi-dependent and independent control of LINE1 accumulation and mobility in mouse embryonic stem cells.
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DOI：
10.1371/journal.pgen.1003791
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发表时间：
2013-11
期刊：
影响因子：
4.5
通讯作者：
Voinnet O
中科院分区：
文献类型：
--
作者：
Ciaudo C;Jay F;Okamoto I;Chen CJ;Sarazin A;Servant N;Barillot E;Heard E;Voinnet O
在大多数小鼠组织中，长散布元件-1 （L1s）通过其5 ' -非翻译区（5 ' -UTR）的甲基化而沉默。着床前胚胎中甲基化的逐渐丧失与囊胚中的L1逆转录相吻合，从而产生潜在的有害突变。在这里，我们发现Dicer和ago2依赖性RNAi限制了来自囊胚的未分化小鼠胚胎干细胞（mESCs）中L1的积累和反转录。RNAi与dicer依赖性22-nt小rna的产生相关，这些小rna映射到L1 5 ' -UTR产生的重叠的义/反义转录物。然而，rna监视途径同时降解这些转录本，因此混淆了抗l1 RNAi反应。在涉及异位Dicer表达的Dicer−/−mESC互补实验中，在microrna仍然强烈缺失的细胞中恢复了L1沉默。此外，这些细胞增殖和分化正常，不像他们的非互补对应。这些结果揭示了L1生物学的新视角，揭示了RNAi的防御和调节作用，并对Dicer−/−mESCs的分化缺陷提出了新的问题。基因调控的基础网络协调确保维持基因组完整性的过程。由RNAse-III Dicer产生的真核小RNA通过RNA干扰（RNAi）介导转录或转录后水平的基因沉默，在该网络中发挥了核心作用。为了深入了解它们在哺乳动物中的潜在发育功能，我们对小鼠胚胎干细胞（mESCs）分化过程中的小RNA表达谱进行了表征，这是一种早期哺乳动物发育模型。长穿插元件1 （L1）是非长末端重复逆转录转座子，在小鼠基因组中占主导地位，并在生殖细胞或早期发育和mESCs中表达。基于植物和分裂酵母的明确先例，我们研究了RNAi和其他基于rna的途径在L1转录和动员调控中的作用。我们的工作揭示了映射到活性L1元件的小rna的存在。其中一些具有Dicer产生的同源siRNA的特征，而另一些则表现出链偏倚和长度异质性，通过RNA监测途径以不依赖Dicer的方式唤起它们的生物发生。此外，DICER或ARGONAUTE蛋白的基因消融对L1的转录和动员具有复杂而深远的影响，这表明内源性RNAi确实能够维持L1增殖的基因组完整性。
In most mouse tissues, long-interspersed elements-1 (L1s) are silenced via methylation of their 5′-untranslated regions (5′-UTR). A gradual loss-of-methylation in pre-implantation embryos coincides with L1 retrotransposition in blastocysts, generating potentially harmful mutations. Here, we show that Dicer- and Ago2-dependent RNAi restricts L1 accumulation and retrotransposition in undifferentiated mouse embryonic stem cells (mESCs), derived from blastocysts. RNAi correlates with production of Dicer-dependent 22-nt small RNAs mapping to overlapping sense/antisense transcripts produced from the L1 5′-UTR. However, RNA-surveillance pathways simultaneously degrade these transcripts and, consequently, confound the anti-L1 RNAi response. In Dicer−/− mESC complementation experiments involving ectopic Dicer expression, L1 silencing was rescued in cells in which microRNAs remained strongly depleted. Furthermore, these cells proliferated and differentiated normally, unlike their non-complemented counterparts. These results shed new light on L1 biology, uncover defensive, in addition to regulatory roles for RNAi, and raise questions on the differentiation defects of Dicer−/− mESCs. A basal network of gene regulation orchestrates the processes ensuring maintenance of genome integrity. Eukaryotic small RNAs generated by the RNAse-III Dicer have emerged as central players in this network, by mediating gene silencing at the transcriptional or post-transcriptional level via RNA interference (RNAi). To gain insight into their potential developmental functions in mammals, we have characterized small RNA expression profiles during mouse Embryonic Stem Cell (mESCs) differentiation, a model for early mammalian development. Long interspersed elements 1 (L1) are non-long-terminal-repeat retrotransposons that dominate the mouse genomic landscape, and are expressed in germ cells or during early development and mESCs. Based on clear precedents in plants and fission yeast, we investigated a role for RNAi and other RNA-based pathways in the regulation of L1 transcription and mobilization. Our work uncovered the existence of small (s)RNAs that map to active L1 elements. Some have characteristics of cognate siRNA produced by Dicer, while others display strand biases and length heterogeneity that evoke their biogenesis through RNA surveillance pathways, in a Dicer-independent manner. Furthermore, genetic ablation of DICER or of ARGONAUTE proteins has complex and profound consequences on L1 transcription and mobilization, indicating that endogenous RNAi do indeed maintain genomic integrity against L1 proliferation.
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DOI：
10.1146/annurev-genom-082509-141802
发表时间：
2011
影响因子：
8.7
作者：
Beck CR;Garcia-Perez JL;Badge RM;Moran JV
通讯作者：
Moran JV
影响因子：
10.5
作者：
Babiarz, Joshua E.;Ruby, J. Graham;Blelloch, Robert
通讯作者：
Blelloch, Robert
影响因子：
4.5
作者：
Ip, Jonathan;Canham, Paul;Mann, Jeffrey R.
通讯作者：
Mann, Jeffrey R.
影响因子：
16
作者：
Aravin, Alexei A.;Sachidanandam, Ravi;Bourc'his, Deborah;Schaefer, Christopher;Pezic, Dubravka;Toth, Katalin Fejes;Bestor, Timothy;Hannon, Gregory J.
通讯作者：
Hannon, Gregory J.
影响因子：
64.8
作者：
Bernstein, E;Caudy, AA;Hannon, GJ
通讯作者：
Hannon, GJ