Departamento de Genética, Universidad de Sevilla, Sevilla 41080, Spain; Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla 41092, Spain.
Departamento de Genética, Universidad de Sevilla, Sevilla 41080, Spain; Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla 41092, Spain.
Cell Rep. 2018 Sep 18;24(12):3262-3273.e4. doi: 10.1016/j.celrep.2018.08.047.
DNA breaks are complex lesions that can be repaired either by non-homologous end joining (NHEJ) or by homologous recombination (HR). The decision between these two routes of DNA repair is a key point of the DNA damage response (DDR) that is controlled by DNA resection. The core machinery catalyzing the resection process is well established. However, little is known about the additional requirements of DNA resection over DNA structures with high complexity. Here, we found evidence that the human helicase PIF1 has a role in DNA resection, specifically for defined DNA regions, such as those prone to form G-quadruplexes. Indeed, PIF1 is recruited to the site of DNA damage and physically interacts with proteins involved in DNA resection, and its depletion causes DNA damage sensitivity and a reduction of HR efficiency. Moreover, G4 stabilization by itself hampers DNA resection, a phenomenon suppressed by PIF1 overexpression.
DNA 断裂是复杂的损伤，可以通过非同源末端连接 (NHEJ) 或同源重组 (HR) 来修复。这两种 DNA 修复途径的选择是 DNA 损伤反应 (DDR) 的关键点，由 DNA 切除控制。催化切除过程的核心机制已经得到很好的建立。然而，对于具有高复杂性的 DNA 结构，DNA 切除的额外要求知之甚少。在这里，我们发现人类解旋酶 PIF1 在 DNA 切除中起作用，特别是对于特定的 DNA 区域，例如那些容易形成 G-四链体的区域。事实上，PIF1 被募集到 DNA 损伤部位，并与参与 DNA 切除的蛋白质发生物理相互作用，其缺失会导致 DNA 损伤敏感性和 HR 效率降低。此外，G4 的稳定本身会阻碍 DNA 切除，而 PIF1 的过表达可以抑制这种现象。
