School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
Interdisciplinary Graduate School, Nanyang Technological University, Singapore, Singapore.
Cell Cycle. 2020 Feb;19(4):405-418. doi: 10.1080/15384101.2020.1711577. Epub 2020 Jan 16.
Protein-protein interaction network analysis plays critical roles in predicting the functions of target proteins. In this study, we used a combination of SILAC-MS proteomics and bioinformatic approaches to identify Checkpoint Kinase 1 (Chk1) as a possible POPX2 phosphatase interacting protein. POPX2 is a PP2C phosphatase that has been implicated in cancer cell invasion and migration. From the Domain-Domain Interaction (DDI) database, we first determined that the PP2C phosphatase domain interacts with Pkinase domain. Subsequently, 46 proteins with Pkinase domain were identified from POPX2 SILAC-MS data. We then narrowed down the leads and confirmed the biological interaction between Chk1 and POPX2. We also found that Chk1 is a substrate of POPX2. Chk1 is a key regulator of the cell cycle and is activated when the cell suffers DNA damage. Our approach has led us to identify POPX2 as a regulator of Chk1 and can interfere with the normal function of Chk1 at G1-S transition of the cell cycle in response to DNA damage.
蛋白质-蛋白质相互作用网络分析在预测靶蛋白的功能方面起着关键作用。在这项研究中，我们使用 SILAC-MS 蛋白质组学和生物信息学方法的组合，鉴定出细胞周期检查点激酶 1（Chk1）可能是 POPX2 磷酸酶相互作用蛋白。POPX2 是一种 PP2C 磷酸酶，已被牵连到癌细胞的侵袭和迁移中。从结构域-结构域相互作用（DDI）数据库中，我们首先确定 PP2C 磷酸酶结构域与 Pkinase 结构域相互作用。随后，从 POPX2 SILAC-MS 数据中鉴定出 46 个具有 Pkinase 结构域的蛋白质。然后，我们缩小了范围并证实了 Chk1 和 POPX2 之间的生物学相互作用。我们还发现 Chk1 是 POPX2 的底物。Chk1 是细胞周期的关键调节剂，当细胞遭受 DNA 损伤时会被激活。我们的方法使我们能够鉴定出 POPX2 是 Chk1 的调节剂，并在细胞周期的 G1-S 转换中响应 DNA 损伤干扰 Chk1 的正常功能。
