Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Graduate School of Biomedical Sciences, Japan.
Biochem Biophys Res Commun. 2011 Aug 12;411(4):762-7. doi: 10.1016/j.bbrc.2011.07.021. Epub 2011 Jul 18.
The cohesin loading factor NIPBL is required for cohesin to associate with chromosomes and plays a role in DNA double-strand break (DSB) repair. Although the NIPBL homolog Scc2 is recruited to an enzymatically generated DSB and promotes cohesin-dependent DSB repair in yeast, the mechanism of the recruitment remains poorly understood. Here we show that the human NIPBL is recruited to the sites of DNA damage generated by micro-irradiation as well as to the sites of DSBs induced by homing endonuclease, I-PpoI. The recruitment of NIPBL was impaired by RNAi-mediated knockdown of MDC1 or RNF168, both of which also accumulate at DSBs. We also show that the recruitment of NIPBL to the sites of DNA damage is mediated by its C-terminal region containing HEAT repeats and Heterochromatin protein 1 (HP1) interacting motif. Furthermore, NIPBL accumulation at damaged sites was also compromised by HP1γ depletion. Taken together, our study reveals that human NIPBL is a novel protein recruited to DSB sites, and the recruitment is controlled by MDC1, RNF168 and HP1γ.
着丝粒加载因子 NIPBL 对于着丝粒与染色体的结合是必需的，并且在 DNA 双链断裂 (DSB) 修复中发挥作用。尽管同源物 Scc2 被募集到酶促产生的 DSB 并促进酵母中依赖于着丝粒的 DSB 修复，但募集的机制仍知之甚少。在这里，我们表明人 NIPBL 被募集到微照射产生的 DNA 损伤部位，以及同源内切酶 I-PpoI 诱导的 DSB 部位。MDC1 或 RNF168 的 RNAi 介导敲低削弱了 NIPBL 的募集，这两者也在 DSB 处积累。我们还表明，NIPBL 对 DNA 损伤部位的募集是由其包含 HEAT 重复和异染色质蛋白 1 (HP1) 相互作用基序的 C 末端区域介导的。此外，HP1γ 的耗竭也损害了 NIPBL 在受损部位的积累。总之，我们的研究表明，人 NIPBL 是一种新募集到 DSB 部位的蛋白，募集受 MDC1、RNF168 和 HP1γ 的控制。
