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Genome Biology:染色质调控siRNAs的表达,有助于维持转座子的甲基化稳态

已有 575 次阅读 2020-9-22 07:45 |个人分类:每日摘要|系统分类:论文交流

Chromatin regulates expression of small RNAs to help maintain transposon methylome homeostasis in Arabidopsis

第一作者Ranjith K. Papareddy

第一单位奥地利孟德尔研究所

通讯作者Michael D. Nodine


 Abstract 


背景回顾Eukaryotic genomes are partitioned into euchromatic and heterochromatic domains to regulate gene expression and other fundamental cellular processes. However, chromatin is dynamic during growth and development and must be properly re-established after its decondensation.


提出问题Small interfering RNAs (siRNAs) promote heterochromatin formation, but little is known about how chromatin regulates siRNA expression. 


主要发现:We demonstrate that thousands of transposable elements (TEs) produce exceptionally high levels of siRNAs in Arabidopsis thaliana embryos.


结果1-胚胎中的两类模式siRNAs:TEs generate siRNAs throughout embryogenesis according to two distinct patterns depending on whether they are located in euchromatic or heterochromatic regions of the genome.


结果2-TEs上DNA甲基化重建:siRNA precursors are transcribed in embryos, and siRNAs are required to direct the re-establishment of DNA methylation on TEs from which they are derived in the new generation.


结果3-解凝染色质Decondensed chromatin also permits the production of 24-nt siRNAs from heterochromatic TEs during post-embryogenesis, and siRNA production from bipartite-classified TEs is controlled by their chromatin states.


结果4-解凝异染色质Decondensation of heterochromatin in response to developmental, and perhaps environmental, cues promotes the transcription and function of siRNAs in plants.


结论:Our results indicate that chromatin-mediated siRNA transcription provides a cell-autonomous homeostatic control mechanism to help reconstitute pre-existing chromatin states during growth and development including those that ensure silencing of TEs in the future germ line.


 摘  要 


真核生物基因组可以分为常染色质和异染色质,调控基因的表达和其它一些基础的细胞学进程。然而,在生长和发育过程中,染色质是动态变化的,在其凝聚之后必须重新凝集。小干扰RNAs(Small interfering RNAs,简称siRNAs)促进异染色质的形成,但是有关染色质如何调控siRNAs的表达还不清楚。本文中,作者发现在拟南芥的胚胎中,数千个转座元件(transposable elements,简称TEs)会产生异常高水平的siRNAs。而且,在胚胎发育过程中TEs会产生两种不同模式的siRNAs,而这种模式主要取决于TEs位于常染色质,还是异染色质区域。在胚胎中,siRNA前体被转录,而且这些siRNA对于其来源TEs在下一代中重新建立起甲基化是必需的。在胚后发育阶段,解凝集的染色质同样能够产生异染色质区域TEs的24-nt siRNAs,而且两类模式TEs产生的siRNAs是由其染色质状态决定的。植物中,异染色质响应于发育信号(或许还有环境信号)而发生解凝聚,促进了siRNAs的转录和功能。本文的研究结果揭示了染色质介导的siRNA转录提供了一个细胞型稳态控制机制,从而在生长和发育过程中,帮助重建先前的染色质状态,从而确保TEs在未来的精细胞系中处于沉默状态。


 通讯作者 


**Michael Nodine**


个人简介:

2002年,美国克莱姆森大学,学士;

2007年,美国亚利桑那大学,博士;

2007-2012年,美国Whitehead生物医学研究所,博后。


研究方向:

植物早期胚胎发生。


doi: 10.1186/s13059-020-02163-4


Journal: Genome Biology

Published date: September 17, 2020



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