Cancer & Ageing Research Program, Centre for Genomics and Personalised Health at the Translational Research Institute (TRI), Queensland University of Technology (QUT), Brisbane, Australia.
School of Science and Health, Western Sydney University, Penrith, NSW, 2751, Australia.
Sci Rep. 2021 Oct 12;11(1):20256. doi: 10.1038/s41598-021-99355-0.
Maintenance of genomic stability is critical to prevent diseases such as cancer. As such, eukaryotic cells have multiple pathways to efficiently detect, signal and repair DNA damage. One common form of exogenous DNA damage comes from ultraviolet B (UVB) radiation. UVB generates cyclobutane pyrimidine dimers (CPD) that must be rapidly detected and repaired to maintain the genetic code. The nucleotide excision repair (NER) pathway is the main repair system for this type of DNA damage. Here, we determined the role of the human Single-Stranded DNA Binding protein 2, hSSB2, in the response to UVB exposure. We demonstrate that hSSB2 levels increase in vitro and in vivo after UVB irradiation and that hSSB2 rapidly binds to chromatin. Depletion of hSSB2 results in significantly decreased Replication Protein A (RPA32) phosphorylation and impaired RPA32 localisation to the site of UV-induced DNA damage. Delayed recruitment of NER protein Xeroderma Pigmentosum group C (XPC) was also observed, leading to increased cellular sensitivity to UVB. Finally, hSSB2 was shown to have affinity for single-strand DNA containing a single CPD and for duplex DNA with a two-base mismatch mimicking a CPD moiety. Altogether our data demonstrate that hSSB2 is involved in the cellular response to UV exposure.
基因组稳定性的维持对于预防癌症等疾病至关重要。因此，真核细胞有多种途径来有效地检测、信号转导和修复 DNA 损伤。一种常见的外源性 DNA 损伤来自于紫外线 B（UVB）辐射。UVB 会产生环丁烷嘧啶二聚体（CPD），必须迅速检测和修复以维持遗传密码。核苷酸切除修复（NER）途径是修复这种类型 DNA 损伤的主要系统。在这里，我们确定了人类单链 DNA 结合蛋白 2（hSSB2）在 UVB 暴露反应中的作用。我们证明 hSSB2 的水平在体外和体内照射 UVB 后增加，并且 hSSB2 迅速结合到染色质上。hSSB2 的耗竭导致复制蛋白 A（RPA32）磷酸化显著减少，并且 RPA32 定位到 UV 诱导的 DNA 损伤部位受损。还观察到 NER 蛋白 Xeroderma Pigmentosum 组 C（XPC）的募集延迟，导致细胞对 UVB 的敏感性增加。最后，还表明 hSSB2 对含有单个 CPD 的单链 DNA 以及模拟 CPD 部分的具有两个碱基错配的双链 DNA 具有亲和力。总之，我们的数据表明 hSSB2 参与了细胞对 UV 暴露的反应。
