Transcriptional cosuppression of yeast Ty1 retrotransposons
Transcriptional cosuppression of yeast Ty1 retrotransposons
复制标题
DOI：
10.1101/gad.923502
复制
发表时间：
2002-02-15
影响因子：
10.5
通讯作者：
Jiang, YW
中科院分区：
文献类型：
--
作者：
Jiang, YW
共抑制，即高拷贝数引发的分散同源基因的沉默，可能已经在真核生物中进化以控制分子寄生虫，如病毒和转座子。Ty 1反转录转座子是酿酒酵母中分散的基因重复序列，以前没有观察到共抑制。Ty 1元件似乎不受阻碍地表达至高达总mRNA的10%的水平。使用Ty 1-URA 3报告和负选择与5-氟乳清酸，它表明，Ty 1基因可以进行转录共抑制，是独立的DNA甲基化和polycomb介导的抑制。Ty 1相关基因的表达被证明是在两种状态之一，共表达状态与所有Ty 1相关基因转录或cosuppressed状态与所有Ty 1相关基因关闭，没有不协调或镶嵌在任何单个细胞中的表达。观察到两种状态之间的快速切换。高拷贝数的Ty 1元件被证明是启动Ty 1同源依赖性基因沉默所必需的，这意味着Ty 1基因表达处于负反馈控制之下。Ty 1转录抑制因子促进了Ty 1共抑制的发生，并且天然Ty 1启动子是Ty 1共抑制所需的，表明Ty 1共抑制发生在转录水平。
Cosuppression, the silencing of dispersed homologous genes triggered by high copy number, may have evolved in eukaryotic organisms to control molecular parasites such as viruses and transposons. Ty1 retrotransposons are dispersed gene repeats in Saccharomyces cerevisiae, where no cosuppression has been previously observed. Ty1 elements are seemingly expressed undeterred to a level as high as 10% of total mRNA. Using Ty1-URA3 reporters and negative selection with 5-fluoroorotic acid, it is shown that Ty1 genes can undergo transcriptional cosuppression that is independent of DNA methylation and polycomb-mediated repression. Expression of Ty1-related genes was shown to be in one of two states, the coexpressed state with all Ty1-related genes transcribed or the cosuppressed state with all Ty1-related genes shut off, without uncoordinated or mosaic expression in any individual cell. Rapid switches between the two states were observed. A high copy number of Ty1 elements was shown to be required for the initiation of Ty1 homology-dependent gene silencing, implying that Ty1 gene expression is under negative feedback control. Ty1 transcriptional repressors facilitated the onset of Ty1 cosuppression, and the native Ty1 promoters were required for Ty1 cosuppression, indicating that Ty1 cosuppression occurs at the transcriptional level.