Yu Yang, Wang Xin, Fox Jordan, Yu Ruofan, Thakre Pilendra, McCauley Brenna, Nikoloutsos Nicolas, Li Qian, Hastings P J, Dang Weiwei, Chen Kaifu, Ira Grzegorz
Baylor College of Medicine, Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA.
Department of Cardiology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
Res Sq. 2024 Jan 5:rs.3.rs-3641411. doi: 10.21203/rs.3.rs-3641411/v1.
In metazoans release of mitochondrial DNA or retrotransposon cDNA to cytoplasm can cause sterile inflammation and disease . Cytoplasmic nucleases degrade these DNA species to limit inflammation . It remains unknown whether degradation these DNA also prevents nuclear genome instability. To address this question, we decided to identify the nuclease regulating transfer of these cytoplasmic DNA species to the nucleus. We used an amplicon sequencing-based method in yeast enabling analysis of millions of DSB repair products. Nuclear mtDNA (NUMTs) and retrotransposon cDNA insertions increase dramatically in nondividing stationary phase cells. Yeast EndoG (Nuc1) nuclease limits insertions of cDNA and transfer of very long mtDNA (>10 kb) that forms unstable circles or rarely insert in the genome, but it promotes formation of short NUMTs (~45-200 bp). Nuc1 also regulates transfer of cytoplasmic DNA to nucleus in aging or during meiosis. We propose that Nuc1 preserves genome stability by degrading retrotransposon cDNA and long mtDNA, while short NUMTs can originate from incompletely degraded mtDNA. This work suggests that nucleases eliminating cytoplasmic DNA play a role in preserving genome stability.
在多细胞动物中，线粒体DNA或逆转录转座子cDNA释放到细胞质中会引发无菌性炎症和疾病。细胞质核酸酶会降解这些DNA种类以限制炎症。这些DNA的降解是否也能防止核基因组不稳定仍不清楚。为了解决这个问题，我们决定鉴定调节这些细胞质DNA种类向细胞核转移的核酸酶。我们在酵母中使用了一种基于扩增子测序的方法，能够分析数百万个双链断裂修复产物。在不分裂的静止期细胞中，核线粒体DNA（NUMTs）和逆转录转座子cDNA插入显著增加。酵母内切酶G（Nuc1）核酸酶限制cDNA的插入以及形成不稳定环或很少插入基因组的超长线粒体DNA（>10 kb）的转移，但它促进短NUMTs（约45 - 200 bp）的形成。Nuc1还在衰老或减数分裂过程中调节细胞质DNA向细胞核的转移。我们提出，Nuc1通过降解逆转录转座子cDNA和长线粒体DNA来维持基因组稳定性，而短NUMTs可能源自未完全降解的线粒体DNA。这项工作表明，消除细胞质DNA的核酸酶在维持基因组稳定性方面发挥作用。
