Kim Hyun-Min, Colaiácovo Monica P
Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America.
PLoS Genet. 2014 Oct 16;10(10):e1004723. doi: 10.1371/journal.pgen.1004723. eCollection 2014 Oct.
Germline mutations in DNA repair genes are linked to tumor progression. Furthermore, failure in either activating a DNA damage checkpoint or repairing programmed meiotic double-strand breaks (DSBs) can impair chromosome segregation. Therefore, understanding the molecular basis for DNA damage response (DDR) and DSB repair (DSBR) within the germline is highly important. Here we define ZTF-8, a previously uncharacterized protein conserved from worms to humans, as a novel factor involved in the repair of both mitotic and meiotic DSBs as well as in meiotic DNA damage checkpoint activation in the C. elegans germline. ztf-8 mutants exhibit specific sensitivity to γ-irradiation and hydroxyurea, mitotic nuclear arrest at S-phase accompanied by activation of the ATL-1 and CHK-1 DNA damage checkpoint kinases, as well as accumulation of both mitotic and meiotic recombination intermediates, indicating that ZTF-8 functions in DSBR. However, impaired meiotic DSBR progression partially fails to trigger the CEP-1/p53-dependent DNA damage checkpoint in late pachytene, also supporting a role for ZTF-8 in meiotic DDR. ZTF-8 partially co-localizes with the 9-1-1 DDR complex and interacts with MRT-2/Rad1, a component of this complex. The human RHINO protein rescues the phenotypes observed in ztf-8 mutants, suggesting functional conservation across species. We propose that ZTF-8 is involved in promoting repair at stalled replication forks and meiotic DSBs by transducing DNA damage checkpoint signaling via the 9-1-1 pathway. Our findings define a conserved function for ZTF-8/RHINO in promoting genomic stability in the germline.
DNA修复基因中的种系突变与肿瘤进展相关。此外，激活DNA损伤检查点或修复程序性减数分裂双链断裂（DSB）失败均会损害染色体分离。因此，了解种系内DNA损伤反应（DDR）和DSB修复（DSBR）的分子基础非常重要。在这里，我们将ZTF-8定义为一种从蠕虫到人类都保守的、以前未被表征的蛋白质，它是参与秀丽隐杆线虫种系有丝分裂和减数分裂DSB修复以及减数分裂DNA损伤检查点激活的新因子。ztf-8突变体对γ辐射和羟基脲表现出特异性敏感性，在S期出现有丝分裂核停滞，并伴有ATL-1和CHK-1 DNA损伤检查点激酶的激活，以及有丝分裂和减数分裂重组中间体的积累，表明ZTF-8在DSBR中发挥作用。然而，减数分裂DSBR进程受损在粗线期后期部分无法触发CEP-1/p53依赖的DNA损伤检查点，这也支持了ZTF-8在减数分裂DDR中的作用。ZTF-8与9-1-1 DDR复合物部分共定位，并与该复合物的一个组分MRT-2/Rad1相互作用。人类RHINO蛋白可挽救ztf-8突变体中观察到的表型，表明跨物种功能保守。我们提出ZTF-8通过9-1-1途径转导DNA损伤检查点信号，参与促进停滞复制叉和减数分裂DSB的修复。我们的研究结果定义了ZTF-8/RHINO在促进种系基因组稳定性方面的保守功能。
