Schramke Vera, Allshire Robin
Wellcome Trust Centre for Cell Biology, Institute of Cell and Molecular Biology, King's Buildings, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK.
Science. 2003 Aug 22;301(5636):1069-74. doi: 10.1126/science.1086870. Epub 2003 Jul 17.
The expression of short hairpin RNAs in several organisms silences gene expression by targeted mRNA degradation. This RNA interference (RNAi) pathway can also affect the genome, as DNA methylation arises at loci homologous to the target RNA in plants. We demonstrate in fission yeast that expression of a synthetic hairpin RNA is sufficient to silence the homologous locus in trans and causes the assembly of a patch of silent Swi6 chromatin with cohesin. This requires components of the RNAi machinery and Clr4 histone methyltransferase for small interfering RNA generation. A similar process represses several meiotic genes through nearby retrotransposon long terminal repeats (LTRs). These analyses directly implicate interspersed LTRs in regulating gene expression during cellular differentiation.
在几种生物体中，短发夹RNA的表达通过靶向mRNA降解使基因表达沉默。这种RNA干扰（RNAi）途径也会影响基因组，因为在植物中，与靶RNA同源的位点会出现DNA甲基化。我们在裂殖酵母中证明，合成发夹RNA的表达足以反式沉默同源位点，并导致带有黏连蛋白的沉默Swi6染色质斑块的组装。这需要RNAi机制的组分和Clr4组蛋白甲基转移酶来生成小干扰RNA。类似的过程通过附近的逆转座子长末端重复序列（LTR）抑制几个减数分裂基因。这些分析直接表明散布的LTR在细胞分化过程中调节基因表达。
