小RNAs在沉默转座因子中的作用

The role of small RNAs in silencing transposable elements

在很多生物基因组中都存在DNA成分的转座序列,它们能够转座到基因组的很多位点,对基因组造成很大的危害,如破坏编码基因、改变基因表达的调节网络、使染色体断裂或造成大范围基因重排等。真核生物已经进化出了多种机制来控制这些寄生核酸序列造成的损伤,以维持基因组完整性。虽然这些机制在不同生物中有些差异,但其中一种主要的机制是通过小RNAs介导的,这些小RNAs包括小干扰RNAs、piwi相互作用的小RNAs、微小RNAs、扫描RNAs和21U-RNAs等。这些小RNAs可以通过DNA水平剪切转座序列,或在转录和(或)转录后水平沉默转座成分。该文就这些小RNAs沉默转座成分的机制和功能做一论述。

Transposable elements （TEs） are DNA elements found in the genomes of various organisms. However,due to their ability to transpose into virtually any locus,TEs have the ability to generate deleterious damages in the host genome,such as disrupting protein-coding genes,altering transcriptional regulatory networks and causing chromosomal breakage or large-scale genomic rearrangement. Eukaryotes has evolved multiple silencing mechanisms as a defense strategy against these parasitic nucleic acids to protect genomic integrity. Although the strategies used in different organisms vary in their details,a major system that controls the activity of TEs,is mediated by small RNAs,including siRNAs,piRNAs,miRNAs,scanRNAs and 21U-RNAs. These small RNAs can tame TEs through eliminating TE sequences or silencing them in transcriptional and/or posttranscriptional level. The functions and the mechanisms of these small RNAs in the ongoing struggle against TEs,were discussed in the following review.