The tumor suppressor CDKN3 controls mitosis

• DOI: 10.1083/jcb.20120512508022013c
• Publication Date: 2013-08-19T13:28:07Z
• Authors: Grzegorz Nalepa; Jill Barnholtz-Sloan; Rikki Enzor; Dilip Dey; Ying He; Jeff R. Gehlhausen; Amalia S. Lehmann; Su-Jung Park; Yanzhu Yang; Xianlin Yang; Shi Chen; Xiaowei Guan; Yanwen Chen; Jamie Renbarger; Feng-Chun Yang; Luis F. Parada; Wade Clapp
• Keywords: Centrosome; 0301 basic medicine; 0303 health sciences; Correction; Mitosis; Cyclin B; Cyclin-Dependent Kinases; Mass Spectrometry; 03 medical and health sciences; CDC2 Protein Kinase; Dual-Specificity Phosphatases; Humans; RNA Interference; Phosphorylation; Kinetochores; Research Articles; Cyclin-Dependent Kinase Inhibitor Proteins; HeLa Cells; Signal Transduction

Mitosis is controlled by a network of kinases and phosphatases. We screened a library of small interfering RNAs against a genome-wide set of phosphatases to comprehensively evaluate the role of human phosphatases in mitosis. We found four candidate spindle checkpoint phosphatases, including the tumor suppressor CDKN3. We show that CDKN3 is essential for normal mitosis and G1/S transition. We demonstrate that subcellular localization of CDKN3 changes throughout the cell cycle. We show that CDKN3 dephosphorylates threonine-161 of CDC2 during mitotic exit and we visualize CDC2pThr-161 at kinetochores and centrosomes in early mitosis. We performed a phosphokinome-wide mass spectrometry screen to find effectors of the CDKN3-CDC2 signaling axis. We found that one of the identified downstream phosphotargets, CKβ phosphorylated at serine 209, localizes to mitotic centrosomes and controls the spindle checkpoint. Finally, we show that CDKN3 protein is down-regulated in brain tumors. Our findings indicate that CDKN3 controls mitosis through the CDC2 signaling axis. These results have implications for targeted anticancer therapeutics.