Keskin Havva, Meers Chance, Storici Francesca
a School of Biology, Georgia Institute of Technology , Atlanta , Georgia , USA.
RNA Biol. 2016;13(2):157-65. doi: 10.1080/15476286.2015.1116676. Epub 2015 Dec 4.
The transfer of genetic information from RNA to DNA is considered an extraordinary process in molecular biology. Despite the fact that cells transcribe abundant amount of RNA with a wide range of functions, it has been difficult to uncover whether RNA can serve as a template for DNA repair and recombination. An increasing number of experimental evidences suggest a direct role of RNA in DNA modification. Recently, we demonstrated that endogenous transcript RNA can serve as a template to repair a DNA double-strand break (DSB), the most harmful DNA lesion, not only indirectly via formation of a DNA copy (cDNA) intermediate, but also directly in a homology driven mechanism in budding yeast. These results point out that the transfer of genetic information from RNA to DNA is more general than previously thought. We found that transcript RNA is more efficient in repairing a DSB in its own DNA (in cis) than in a homologous but ectopic locus (in trans). Here, we summarize current knowledge about the process of RNA-driven DNA repair and recombination, and provide further data in support of our model of DSB repair by transcript RNA in cis. We show that a DSB is precisely repaired predominately by transcript RNA and not by residual cDNA in conditions in which formation of cDNA by reverse transcription is inhibited. Additionally, we demonstrate that defects in ribonuclease (RNase) H stimulate precise DSB repair by homologous RNA or cDNA sequence, and not by homologous DNA sequence carried on a plasmid. These results highlight an antagonistic role of RNase H in RNA-DNA recombination. Ultimately, we discuss several questions that should be addressed to better understand mechanisms and implications of RNA-templated DNA repair and recombination.
在分子生物学中,遗传信息从RNA到DNA的转移被认为是一个非凡的过程。尽管细胞转录了大量具有广泛功能的RNA,但一直难以揭示RNA是否能作为DNA修复和重组的模板。越来越多的实验证据表明RNA在DNA修饰中具有直接作用。最近,我们证明内源性转录RNA不仅可以通过形成DNA拷贝(cDNA)中间体间接作为修复最有害的DNA损伤——DNA双链断裂(DSB)的模板,还可以在芽殖酵母中通过同源驱动机制直接作为模板。这些结果表明,遗传信息从RNA到DNA的转移比以前认为的更为普遍。我们发现转录RNA在修复其自身DNA中的DSB(顺式)时比在同源但异位位点(反式)更有效。在这里,我们总结了关于RNA驱动的DNA修复和重组过程的当前知识,并提供了进一步的数据来支持我们的顺式转录RNA修复DSB的模型。我们表明,在逆转录形成cDNA受到抑制的条件下,DSB主要由转录RNA精确修复,而不是由残留的cDNA修复。此外,我们证明核糖核酸酶(RNase)H的缺陷会刺激同源RNA或cDNA序列而非质粒携带的同源DNA序列对DSB进行精确修复。这些结果突出了RNase H在RNA-DNA重组中的拮抗作用。最后,我们讨论了几个为更好地理解RNA模板化DNA修复和重组的机制及影响而应解决的问题。