MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA.
Mol Cell. 2014 May 8;54(3):472-84. doi: 10.1016/j.molcel.2014.03.014. Epub 2014 Apr 10.
SLX4 binds to three nucleases (XPF-ERCC1, MUS81-EME1, and SLX1), and its deficiency leads to genomic instability, sensitivity to DNA crosslinking agents, and Fanconi anemia. However, it is not understood how SLX4 and its associated nucleases act in DNA crosslink repair. Here, we uncover consequences of mouse Slx4 deficiency and reveal its function in DNA crosslink repair. Slx4-deficient mice develop epithelial cancers and have a contracted hematopoietic stem cell pool. The N-terminal domain of SLX4 (mini-SLX4) that only binds to XPF-ERCC1 is sufficient to confer resistance to DNA crosslinking agents. Recombinant mini-SLX4 enhances XPF-ERCC1 nuclease activity up to 100-fold, directing specificity toward DNA forks. Mini-SLX4-XPF-ERCC1 also vigorously stimulates dual incisions around a DNA crosslink embedded in a synthetic replication fork, an essential step in the repair of this lesion. These observations define vertebrate SLX4 as a tumor suppressor, which activates XPF-ERCC1 nuclease specificity in DNA crosslink repair.
SLX4 与三种核酸内切酶（XPF-ERCC1、MUS81-EME1 和 SLX1）结合，其缺失会导致基因组不稳定、对 DNA 交联剂敏感和范可尼贫血。然而，目前尚不清楚 SLX4 及其相关核酸内切酶在 DNA 交联修复中的作用。在这里，我们揭示了小鼠 Slx4 缺失的后果，并揭示了它在 DNA 交联修复中的功能。Slx4 缺陷型小鼠会发展成上皮癌，并出现造血干细胞池收缩。仅与 XPF-ERCC1 结合的 SLX4 的 N 端结构域（mini-SLX4）足以赋予对 DNA 交联剂的抗性。重组 mini-SLX4 将 XPF-ERCC1 核酸酶活性提高了 100 倍，使其特异性指向 DNA 分叉。mini-SLX4-XPF-ERCC1 还强烈刺激 DNA 交联嵌入合成复制叉中的双切口，这是修复这种损伤的关键步骤。这些观察结果将脊椎动物 SLX4 定义为肿瘤抑制因子，它可激活 DNA 交联修复中的 XPF-ERCC1 核酸内切酶特异性。
