Analysis of small RNA in fission yeast; centromeric siRNAs are potentially generated through a structured RNA
Analysis of small RNA in fission yeast; centromeric siRNAs are potentially generated through a structured RNA
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DOI：
10.1038/emboj.2009.351
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发表时间：
2009-12-16
期刊：
影响因子：
11.4
通讯作者：
Ekwall, Karl
中科院分区：
文献类型：
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作者：
Djupedal, Ingela;Kos-Braun, Isabelle C.;Ekwall, Karl
裂殖酵母着丝粒处异染色质的形成依赖于外部重复序列的转录。这些转录产物被加工成小干扰RNA（siRNAs），其靶向同源位点以形成异染色质。在此，小RNA的高通量测序对着丝粒衍生的小RNA进行了全面分析。我们发现着丝粒小RNA依赖于Dcr1，带有5′ - 单磷酸，并且与Ago1相关联。大多数着丝粒小RNA源自存在于所有着丝粒中的两个高度保守的序列。这种高度相似性表明该非编码序列本身可能很重要。与此一致的是，二级结构探测实验表明这种着丝粒RNA部分是双链的，并且在体外可被Dicer加工。我们进一步证明了在rdp1Δ细胞中存在小的着丝粒RNA。我们的数据表明了一种生成siRNA的途径，它不同于已充分记录的涉及RITS/RDRC的模型。我们提出初级转录本折叠成发夹样结构，可能被Dcr1加工成siRNAs，并且这些siRNAs可能在不依赖RDRC活性的情况下启动异染色质的形成。《欧洲分子生物学组织杂志》（2009年）28卷，3832 - 3844页。doi:10.1038/emboj.2009.351；2009年11月26日在线发表
The formation of heterochromatin at the centromeres in fission yeast depends on transcription of the outer repeats. These transcripts are processed into siRNAs that target homologous loci for heterochromatin formation. Here, high throughput sequencing of small RNA provides a comprehensive analysis of centromere-derived small RNAs. We found that the centromeric small RNAs are Dcr1 dependent, carry 50-monophosphates and are associated with Ago1. The majority of centromeric small RNAs originate from two remarkably well-conserved sequences that are present in all centromeres. The high degree of similarity suggests that this non-coding sequence in itself may be of importance. Consistent with this, secondary structure-probing experiments indicate that this centromeric RNA is partially double-stranded and is processed by Dicer in vitro. We further demonstrate the existence of small centromeric RNA in rdp1D cells. Our data suggest a pathway for siRNA generation that is distinct from the well-documented model involving RITS/RDRC. We propose that primary transcripts fold into hairpin-like structures that may be processed by Dcr1 into siRNAs, and that these siRNAs may initiate heterochromatin formation independent of RDRC activity. The EMBO Journal (2009) 28, 3832-3844. doi: 10.1038/emboj.2009.351; Published online 26 November 2009