Small regulatory RNAs inhibit RNA polymerase II during the elongation phase of transcription.
Small regulatory RNAs inhibit RNA polymerase II during the elongation phase of transcription.
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作者：
真核细胞表达各种各样的内源性小调控RNA，其调节异染色质形成、发育时机、对寄生核酸的防御和基因组重排。许多小的调节RNA被认为在细胞核中起作用。例如，在植物和真菌中，siRNA与新生转录物结合并指导染色质和/或DNA修饰。为了进一步了解小调控RNA的生物学作用，我们进行了一个遗传筛选，以确定RNA干扰（RNAi）所需的因素，在C。elegans核在这里，我们表明，nrde-2编码一个进化上保守的蛋白质，所需的小干扰（si）RNA介导的沉默在细胞核中。NRDE-2在细胞核内与Argonaute蛋白NRDE-3结合，并被NRDE-3/siRNA复合物募集到已被RNAi靶向的新生转录物。我们发现，核定位的siRNA指导前体mRNA 3'至RNAi位点的NRDE-2依赖性沉默，RNA聚合酶（RNAP）II在RNAi靶向的基因组位点的NRDE-2依赖性积累，以及RNAP II占据和RNAP II转录活性3'至RNAi位点的NRDE-2依赖性降低。这些结果将NRDE-2定义为核RNAi机制的一个组成部分，并证明后生动物siRNA可以共转录沉默核定位RNA。此外，这些结果建立了RNAP II调节的新模式;在转录的延伸阶段抑制RNAP II的NRDE因子的siRNA定向募集。
Eukaryotic cells express a wide variety of endogenous small regulatory RNAs that regulate heterochromatin formation, developmental timing, defense against parasitic nucleic acids, and genome rearrangement. Many small regulatory RNAs are thought to function in nuclei. For instance, in plants and fungi siRNAs associate with nascent transcripts and direct chromatin and/or DNA modifications. To further understand the biological roles of small regulatory RNAs, we conducted a genetic screen to identify factors required for RNA interference (RNAi) in C. elegans nuclei. Here we show that nrde-2 encodes an evolutionarily conserved protein that is required for small interfering (si)RNA-mediated silencing in nuclei. NRDE-2 associates with the Argonaute protein NRDE-3 within nuclei and is recruited by NRDE-3/siRNA complexes to nascent transcripts that have been targeted by RNAi. We find that nuclear-localized siRNAs direct a NRDE-2-dependent silencing of pre-mRNAs 3’ to sites of RNAi, a NRDE-2-dependent accumulation of RNA Polymerase (RNAP) II at genomic loci targeted by RNAi, and NRDE-2-dependent decreases in RNAP II occupancy and RNAP II transcriptional activity 3’ to sites of RNAi. These results define NRDE-2 as a component of the nuclear RNAi machinery and demonstrate that metazoan siRNAs can silence nuclear-localized RNAs co-transcriptionally. In addition, these results establish a novel mode of RNAP II regulation; siRNA-directed recruitment of NRDE factors that inhibit RNAP II during the elongation phase of transcription.
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DOI：
10.1073/pnas.95.26.15502
发表时间：
1998-12-22
影响因子：
11.1
作者：
Montgomery, MK;Xu, SQ;Fire, A
通讯作者：
Fire, A
DOI：
10.1126/science.1157647
发表时间：
2008-07-25
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Guang S;Bochner AF;Pavelec DM;Burkhart KB;Harding S;Lachowiec J;Kennedy S
通讯作者：
Kennedy S
影响因子：
56.9
作者：
Liu, JD;Carmell, MA;Hannon, GJ
通讯作者：
Hannon, GJ
影响因子：
64.8
作者：
Moazed, Danesh
通讯作者：
Moazed, Danesh
影响因子：
64.8
作者：
Kamath, RS;Fraser, AG;Ahringer, J
通讯作者：
Ahringer, J