Phosphatase POPX2 interferes with cell cycle by interacting with Chk1

• Published in: Cell cycle (Georgetown, Tex.) Vol. 19; no. 4; pp. 405 - 418
• Main Authors: Kim, Pu Rum, Koon, Yen Ling, Lee, Raphael Tze Chuen, Azizan, Farouq, Koh, Dylan Hong Zheng, Chiam, Keng-Hwee, Koh, Cheng-Gee
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 16-02-2020
• Subjects: Amino Acid Sequence; Cell Cycle; Cell Line; Checkpoint Kinase 1 - metabolism; Chk1 kinase; DNA Damage; DNA damage pathway; G1-S checkpoint; Gene Silencing; Humans; Models, Biological; Phosphoprotein Phosphatases - chemistry; Phosphoprotein Phosphatases - metabolism; Phosphorylation; Phylogeny; POPX2 phosphatase; Protein Binding; Protein Domains; Protein Interaction Mapping; Protein-Protein Interactions; Reproducibility of Results; Research Paper; Structural Homology, Protein; Substrate Specificity; Protein–Protein Interactions; DNA damage pathway; Chk1 kinase; G1-S checkpoint; POPX2 phosphatase
• ISSN: 1538-4101; 1551-4005
• DOI: 10.1080/15384101.2020.1711577

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.