Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA.
Proc Natl Acad Sci U S A. 2013 Feb 5;110(6):2175-80. doi: 10.1073/pnas.1217781110. Epub 2013 Jan 23.
The master checkpoint kinase ATR (ATM and Rad3-related) and its partner ATRIP (ATR-interacting protein) exist as a complex and function together in the DNA damage response. Unexpectedly, we found that the stability of the ATR-ATRIP complex is regulated by an unknown kinase independently of DNA damage. In search for this regulator of ATR-ATRIP, we found that a single member of the NIMA (never in mitosis A)-related kinase family, Nek1, is critical for initiating the ATR response. Upon DNA damage, cells lacking Nek1 failed to efficiently phosphorylate multiple ATR substrates and support ATR autophosphorylation at threnine 1989, one of the earliest events during the ATR response. The ability of Nek1 to promote ATR activation relies on the kinase activity of Nek1 and its interaction with ATR-ATRIP. Importantly, even in undamaged cells, Nek1 is required for maintaining the levels of ATRIP, the association between ATR and ATRIP, and the basal kinase activity of ATR. Thus, as an ATR-associated kinase, Nek1, enhances the stability and activity of ATR-ATRIP before DNA damage, priming ATR-ATRIP for a robust DNA damage response.
主检查点激酶 ATR（共济失调毛细血管扩张症突变相关基因和 Rad3 相关）及其伴侣 ATRIP（ATR 相互作用蛋白）作为复合物存在，并在 DNA 损伤反应中协同发挥作用。出乎意料的是，我们发现 ATR-ATRIP 复合物的稳定性受一种未知激酶的调节，而与 DNA 损伤无关。在寻找这个 ATR-ATRIP 的调节因子时，我们发现丝裂期相关激酶 NIMA（never in mitosis A）家族的一个单一成员 Nek1，对于启动 ATR 反应至关重要。在 DNA 损伤后，缺乏 Nek1 的细胞无法有效地磷酸化多个 ATR 底物，并支持 ATR 自身在苏氨酸 1989 位的磷酸化，这是 ATR 反应早期的事件之一。Nek1 促进 ATR 激活的能力依赖于 Nek1 的激酶活性及其与 ATR-ATRIP 的相互作用。重要的是，即使在未受损的细胞中，Nek1 也需要维持 ATRIP 的水平、ATR 与 ATRIP 之间的关联以及 ATR 的基础激酶活性。因此，作为 ATR 相关激酶，Nek1 在 DNA 损伤之前增强了 ATR-ATRIP 的稳定性和活性，为强大的 DNA 损伤反应做好了准备。
