RNA-directed DNA methylation
RNA-directed DNA methylation
复制标题
DOI：
10.1242/jcs.01479
复制
发表时间：
2004-10-01
影响因子：
4
通讯作者：
Bender, J
中科院分区：
文献类型：
--
作者：
Mathieu, O;Bender, J
双链RNA（dsRNA）及其“切割”的小RNA产物可以指导真核生物的关键发育和防御机制。一些RNA介导的机制在转录后水平起作用以降解靶信使RNA。然而，dsRNA衍生的物种也可以直接改变与它们共享序列同一性的DNA区域的染色质结构。例如，植物利用这种RNA种类在相同的DNA序列上留下胞嘧啶甲基化印记，为转录沉默的异染色质的形成提供了基本标记。因此，RNA可以反馈调节储存在同源基因DNA中的信息的可及性。DNA甲基化的RNA触发物可以来自不同的来源，包括侵入性病毒、转基因或转座子序列，并且在某些情况下通过RNA依赖性RNA聚合酶衍生自单链RNA前体。RNA信号被翻译成DNA甲基化印记的机制目前尚不清楚，但两种植物特异性类型的胞嘧啶甲基转移酶参与了这一过程。RNA也可以指导裂殖酵母和果蝇中异染色质的形成，但在这些生物中，该过程发生在没有DNA甲基化的情况下。
Double-stranded RNAs (dsRNAs) and their 'diced' small RNA products can guide key developmental and defense mechanisms in eukaryotes. Some RNA-directed mechanisms act at a post-transcriptional level to degrade target messenger RNAs. However, dsRNA-derived species can also direct changes in the chromatin structure of DNA regions with which they share sequence identity. For example, plants use such RNA species to lay down cytosine methylation imprints on identical DNA sequences, providing a fundamental mark for the formation of transcriptionally silent heterochromatin. Thus, RNA can feed backwards to modulate the accessibility of information stored in the DNA of cognate genes. RNA triggers for DNA methylation can come from different sources, including invasive viral, transgene or transposon sequences, and in some cases are derived from single-stranded RNA precursors by RNA-dependent RNA polymerases. The mechanism by which RNA signals are translated into DNA methylation imprints is currently unknown, but two plant-specific types of cytosine methyltransferase have been implicated in this process. RNA can also direct heterochromatin formation in fission yeast and Drosophila, but in these organisms the process occurs in the absence of DNA methylation.