Indiana University School of Medicine, Department of Medical and Molecular Genetics, Indianapolis, IN 46202, USA.
Free Radic Biol Med. 2012 Sep 1;53(5):1192-7. doi: 10.1016/j.freeradbiomed.2012.07.024. Epub 2012 Jul 27.
Several lines of evidence suggest that the telomere-associated protein TRF2 plays critical roles in the DNA damage response. TRF2 is rapidly and transiently phosphorylated by an ATM-dependent pathway in response to DNA damage and this DNA damage-induced phosphoryation is essential for the DNA-PK-dependent pathway of DNA double-strand break repair (DSB). However, the type of DNA damage that induces TRF2 localization to the damage sites, the requirement for DNA damage-induced phosphorylation of TRF2 for its recruitment, as well as the detailed kinetics of TRF2 accumulation at DNA damage sites have not been fully investigated. In order to address these questions, we used an ultrafast femtosecond multiphoton laser and a continuous wave 405-nm single photon laser to induce DNA damage at defined nuclear locations. Our results showed that DNA damage produced by a femtosecond multiphoton laser was sufficient for localization of TRF2 to these DNA damage sites. We also demonstrate that ectopically expressed TRF2 was recruited to DNA lesions created by a 405-nm laser. Our data suggest that ATM and DNA-PKcs kinases are not required for TRF2 localization to DNA damage sites. Furthermore, we found that phosphorylation of TRF2 at residue T188 was not essential for its recruitment to laser-induced DNA damage sites. Thus, we provide further evidence that a protein known to function in telomere maintenance, TRF2, is recruited to sites of DNA damage and plays critical roles in the DNA damage response.
有几条证据表明，端粒相关蛋白 TRF2 在 DNA 损伤反应中发挥着关键作用。TRF2 可被 ATM 依赖性途径快速且短暂地磷酸化，以响应 DNA 损伤，这种 DNA 损伤诱导的磷酸化对于 DNA-PK 依赖性的 DNA 双链断裂修复（DSB）途径至关重要。然而，诱导 TRF2 定位到损伤部位的 DNA 损伤类型、TRF2 募集所需的 DNA 损伤诱导磷酸化、以及 TRF2 在 DNA 损伤部位的积累的详细动力学尚未得到充分研究。为了解决这些问题，我们使用超快飞秒多光子激光和连续波 405nm 单光子激光在特定核位置诱导 DNA 损伤。我们的结果表明，飞秒多光子激光产生的 DNA 损伤足以使 TRF2 定位到这些 DNA 损伤部位。我们还证明，异位表达的 TRF2 被招募到 405nm 激光产生的 DNA 损伤部位。我们的数据表明，ATM 和 DNA-PKcs 激酶对于 TRF2 定位到 DNA 损伤部位不是必需的。此外，我们发现 TRF2 残基 T188 的磷酸化对于其招募到激光诱导的 DNA 损伤部位不是必需的。因此，我们提供了进一步的证据表明，一种已知在端粒维持中发挥作用的蛋白 TRF2 被招募到 DNA 损伤部位，并在 DNA 损伤反应中发挥关键作用。
