Meir Michal, Galanty Yaron, Kashani Lior, Blank Michael, Khosravi Rami, Fernández-Ávila María Jesús, Cruz-García Andrés, Star Ayelet, Shochot Lea, Thomas Yann, Garrett Lisa J, Chamovitz Daniel A, Bodine David M, Kurz Thimo, Huertas Pablo, Ziv Yael, Shiloh Yosef
The David and Inez Myers Laboratory for Cancer Research, Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, George S. Wise Faculty of Life sciences, Tel Aviv University, Tel Aviv, 69978 Israel.
The David and Inez Myers Laboratory for Cancer Research, Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, George S. Wise Faculty of Life sciences, Tel Aviv University, Tel Aviv, 69978 Israel
Nucleic Acids Res. 2015 May 19;43(9):4517-30. doi: 10.1093/nar/gkv270. Epub 2015 Apr 8.
The DNA damage response is vigorously activated by DNA double-strand breaks (DSBs). The chief mobilizer of the DSB response is the ATM protein kinase. We discovered that the COP9 signalosome (CSN) is a crucial player in the DSB response and an ATM target. CSN is a protein complex that regulates the activity of cullin ring ubiquitin ligase (CRL) complexes by removing the ubiquitin-like protein, NEDD8, from their cullin scaffold. We find that the CSN is physically recruited to DSB sites in a neddylation-dependent manner, and is required for timely repair of DSBs, affecting the balance between the two major DSB repair pathways-nonhomologous end-joining and homologous recombination repair (HRR). The CSN is essential for the processivity of deep end-resection-the initial step in HRR. Cullin 4a (CUL4A) is recruited to DSB sites in a CSN- and neddylation-dependent manner, suggesting that CSN partners with CRL4 in this pathway. Furthermore, we found that ATM-mediated phosphorylation of CSN subunit 3 on S410 is critical for proper DSB repair, and that loss of this phosphorylation site alone is sufficient to cause a DDR deficiency phenotype in the mouse. This novel branch of the DSB response thus significantly affects genome stability.
DNA双链断裂（DSB）会强力激活DNA损伤反应。DSB反应的主要启动者是ATM蛋白激酶。我们发现，COP9信号体（CSN）是DSB反应中的关键参与者且是ATM的作用靶点。CSN是一种蛋白复合体，通过从其cullin支架上去除类泛素蛋白NEDD8来调节cullin环泛素连接酶（CRL）复合体的活性。我们发现CSN以一种依赖于NEDD化的方式被物理性募集到DSB位点，并且是DSB及时修复所必需的，影响着两种主要的DSB修复途径——非同源末端连接和同源重组修复（HRR）之间的平衡。CSN对于深度末端切除（HRR的初始步骤）的持续进行至关重要。Cullin 4a（CUL4A）以一种依赖于CSN和NEDD化的方式被募集到DSB位点，这表明CSN在该途径中与CRL4协同作用。此外，我们发现ATM介导的CSN亚基3在S410位点的磷酸化对于正确的DSB修复至关重要，并且仅该磷酸化位点的缺失就足以在小鼠中导致DNA损伤反应缺陷表型。因此，DSB反应的这一新分支显著影响基因组稳定性。
