Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
Nat Commun. 2022 Oct 10;13(1):5971. doi: 10.1038/s41467-022-33535-y.
The pathways involved in suppressing DNA replication stress and the associated DNA damage are critical to maintaining genome integrity. The Mre11 complex is unique among double strand break (DSB) repair proteins for its association with the DNA replication fork. Here we show that Mre11 complex inactivation causes DNA replication stress and changes in the abundance of proteins associated with nascent DNA. One of the most highly enriched proteins at the DNA replication fork upon Mre11 complex inactivation was the ubiquitin like protein ISG15. Mre11 complex deficiency and drug induced replication stress both led to the accumulation of cytoplasmic DNA and the subsequent activation of innate immune signaling via cGAS-STING-Tbk1. This led to ISG15 induction and protein ISGylation, including constituents of the replication fork. ISG15 plays a direct role in preventing replication stress. Deletion of ISG15 was associated with replication fork stalling, tonic ATR activation, genomic aberrations, and sensitivity to aphidicolin. These data reveal a previously unrecognized role for ISG15 in mitigating DNA replication stress and promoting genomic stability.
参与抑制 DNA 复制应激和相关 DNA 损伤的途径对于维持基因组完整性至关重要。Mre11 复合物在双链断裂 (DSB) 修复蛋白中是独特的，因为它与 DNA 复制叉相关联。在这里，我们表明 Mre11 复合物失活会导致 DNA 复制应激和与新生 DNA 相关的蛋白质丰度发生变化。在 Mre11 复合物失活时，在 DNA 复制叉上最丰富的蛋白质之一是泛素样蛋白 ISG15。Mre11 复合物缺陷和药物诱导的复制应激都会导致细胞质 DNA 的积累，随后通过 cGAS-STING-Tbk1 激活先天免疫信号。这导致 ISG15 的诱导和蛋白质 ISG 化，包括复制叉的成分。ISG15 在防止复制应激方面发挥直接作用。ISG15 的缺失与复制叉停滞、持续的 ATR 激活、基因组畸变以及对阿霉素的敏感性有关。这些数据揭示了 ISG15 在减轻 DNA 复制应激和促进基因组稳定性方面的先前未被认识的作用。
