An ARGONAUTE4-containing nuclear processing center colocalized with Cajal bodies in Arabidopsis thaliana
An ARGONAUTE4-containing nuclear processing center colocalized with Cajal bodies in Arabidopsis thaliana
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DOI：
10.1016/j.cell.2006.05.032
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发表时间：
2006-07-14
期刊：
影响因子：
64.5
通讯作者：
Jacobsen, Steven E.
中科院分区：
文献类型：
--
作者：
Li, Carey Fei;Pontes, Olga;Jacobsen, Steven E.
在拟南芥中，由24个核苷酸小干扰RNA(SiRNAs)引导的DNA甲基化需要ARGONAUTE4(AGO4)和RNA聚合酶IV(POL IV)。在这里，我们发现AGO4与Pol IV亚基NRPD1b、小核RNA(SnRNA)结合蛋白SmD3以及Cajal小体的两个标记--三甲基鸟苷封顶的SnRNAs和U2 SnRNA结合蛋白U2B一起定位于核仁相关小体。AGO4与NRPD1b的C-末端结构域相互作用，AGO(4)蛋白质的稳定性取决于合成siRNA的上游因素。AGO(4)与DNA甲基转移酶DRM2一起，在假定的DNA甲基化靶点贯穿整个细胞核。Cajal小体是核糖核蛋白复合体成熟的保守部位。我们的结果表明，Cajal小体作为AGO(4)/NRPD1b/siRNA复合体组装的中心，促进了其在RNA导向的靶基因沉默中的功能。
ARGONAUTE4 (AGO4) and RNA polymerase IV (Pol IV) are required for DNA methylation guided by 24 nucleotide small interfering RNAs (siRNAs) in Arabidopsis thaliana. Here we show that AGO4 localizes to nucleolus-associated bodies along with the Pol IV subunit NRPD1b; the small nuclear RNA (snRNA) binding protein SmD3; and two markers of Cajal bodies, trimethylguanosine-capped snRNAs and the U2 snRNA binding protein U2B". AGO4 interacts with the C-terminal domain of NRPD1b, and AGO(4) protein stability depends on upstream factors that synthesize siRNAs. AGO(4) is also found, along with the DNA methyltransferase DRM2, throughout the nucleus at presumed DNA methylation target sites. Cajal bodies are conserved sites for the maturation of ribonucleoprotein complexes. Our results suggest a function for Cajal bodies as a center for the assembly of an AGO(4)/NRPD1b/siRNA complex, facilitating its function in RNA-directed gene silencing at target loci.