The ribosomal RNA genes (rDNA) exist as tandem repeats in eukaryotes and are, therefore, highly unstable. Each rDNA unit includes a replication fork barrier site to avoid collisions between DNA replication forks and transcriptional machinery. However, because of this barrier, DNA double-strand breaks are induced at a relatively high frequency. If damage is repaired by the homologous recombination in rDNAs, it may result in frequent copy number changes and the production of extrachromosomal ribosomal DNA circles, both of which are closely linked to the regulation of lifespan. Here, we review recent progress in elucidating a multi-layered repair process of rDNA that occurs in the nucleolus, nucleoplasm and nuclear pores. Binding to nuclear pores appears to be the final strategy for repairing any remaining damage to the rDNA. Here, we propose the possible contribution of nuclear pores to the asymmetric distribution of damaged rDNA between mother and daughter cells as well as its possible impact on aging/rejuvenation.

中文翻译：

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核糖体RNA基因的复兴在核孔处重复。

核糖体RNA基因（rDNA）在真核生物中以串联重复的形式存在，因此非常不稳定。每个rDNA单元均包含一个复制叉屏障位点，以避免DNA复制叉与转录机制之间发生碰撞。然而，由于该屏障，以相对较高的频率诱导DNA双链断裂。如果通过rDNA的同源重组修复损伤，则可能导致频繁的拷贝数变化和染色体外核糖体DNA环的产生，这两者均与寿命的调节紧密相关。在这里，我们审查阐明在核仁，核质和核孔中发生的rDNA的多层修复过程的最新进展。结合核孔似乎是修复rDNA的任何剩余损伤的最终策略。这里，