The Fanconi Anemia Pathway Protects Genome Integrity from R-loops.
The Fanconi Anemia Pathway Protects Genome Integrity from R-loops.
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DOI：
10.1371/journal.pgen.1005674
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发表时间：
2015-11
期刊：
影响因子：
4.5
通讯作者：
Aguilera A
中科院分区：
文献类型：
--
作者：
García-Rubio ML;Pérez-Calero C;Barroso SI;Tumini E;Herrera-Moyano E;Rosado IV;Aguilera A
共转录的RNA-DNA杂交体(R环)导致基因组不稳定。为了防止有害的R环堆积，细胞进化出特定的真核因子，其中之一是BRCA2双链断裂修复蛋白。由于BRCA2也保护停滞的复制分叉，并且是Fanconi贫血(FA)途径的FANCD1成员，我们研究了FA在R环依赖的基因组不稳定性中的作用。利用FANCD2或FANCA缺陷的人和小鼠细胞以及FANCD2缺陷小鼠的原代骨髓细胞，我们发现FA途径去除了R环，并且FA细胞中积累的许多DNA断裂是R环依赖的。重要的是，未经处理和MMC处理的细胞中的FANCD2焦点在很大程度上是R环依赖的，这表明FA在包含R环的位置起作用。我们得出结论，共转录的R环和R环介导的DNA损伤极大地促进了基因组的不稳定，FA途径的一个主要功能是保护细胞免受R环的影响。R环是共转录的RNA-DNA杂交体，可以在转录和复制中发挥生理作用，但也可能是对基因组稳定性的主要威胁。为了避免R环的有害影响，特定的因素可以防止它们的形成或促进它们的移除。双链断裂修复因子BRCA2是防止R-环积累的因子之一。由于BRCA2也保护停滞的复制分叉，并且是Fanconi贫血(FA)途径的FANCD1成员，我们研究了该途径在防止R环积累和R环依赖的基因组不稳定中的作用。利用FANCD2或FANCA缺陷的人和小鼠细胞以及FANCD2缺陷小鼠的原代骨髓细胞，我们证明FA途径去除了R环，并且FA细胞中积累的许多DNA断裂是R环依赖的。重要的是，FANCD2病灶的聚集在很大程度上是R环依赖的，这表明FA在包含R环的位置起作用。FA途径主要被称为DNA链间交联链(ICLS)修复途径。我们的发现揭示了FA通路在防止R环介导的DNA损伤方面的新功能，为理解R环作为基因组不稳定的自然来源及其处理方式的相关性提供了新的线索。
Co-transcriptional RNA-DNA hybrids (R loops) cause genome instability. To prevent harmful R loop accumulation, cells have evolved specific eukaryotic factors, one being the BRCA2 double-strand break repair protein. As BRCA2 also protects stalled replication forks and is the FANCD1 member of the Fanconi Anemia (FA) pathway, we investigated the FA role in R loop-dependent genome instability. Using human and murine cells defective in FANCD2 or FANCA and primary bone marrow cells from FANCD2 deficient mice, we show that the FA pathway removes R loops, and that many DNA breaks accumulated in FA cells are R loop-dependent. Importantly, FANCD2 foci in untreated and MMC-treated cells are largely R loop dependent, suggesting that the FA functions at R loop-containing sites. We conclude that co-transcriptional R loops and R loop-mediated DNA damage greatly contribute to genome instability and that one major function of the FA pathway is to protect cells from R loops. R loops are co-transcriptional RNA-DNA hybrids that can have a physiological role in transcription and replication, but also may be a major threat to genome stability. To avoid the deleterious effects of R loops, specific factors prevent their formation or facilitate their removal. The double-strand break repair factor BRCA2 is among those that prevent R-loop accumulation. As BRCA2 also protects stalled replication forks and is the FANCD1 member of the Fanconi Anemia (FA) pathway, we studied the role of this pathway in preventing R loop accumulation and R loop-dependent genome instability. Using human and murine cells defective in FANCD2 or FANCA and primary bone marrow cells derived from FANCD2 deficient mice, we show that the FA pathway removes R loops and that many DNA breaks accumulated in FA cells are R loop-dependent. Importantly, FANCD2 foci accumulation is largely R loop-dependent, suggesting that the FA functions at R loop-containing sites. The FA pathway is primarily known as a DNA interstrand crosslinks (ICLs) repair pathway. Our findings reveal a novel function of the FA pathway in preventing R loop-mediated DNA damage, providing new clues to understand the relevance of R-loops as a natural source of genome instability and the way they are processed.