The tumor suppressor CDKN3 controls mitosis

J Cell Biol. 2013 Jun 24;201(7):997-1012. doi: 10.1083/jcb.201205125. Epub 2013 Jun 17.

Abstract

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 CDC2(pThr-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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • CDC2 Protein Kinase
  • Centrosome / metabolism
  • Centrosome / ultrastructure
  • Cyclin B / metabolism
  • Cyclin-Dependent Kinase Inhibitor Proteins / analysis
  • Cyclin-Dependent Kinase Inhibitor Proteins / metabolism
  • Cyclin-Dependent Kinase Inhibitor Proteins / physiology*
  • Cyclin-Dependent Kinases
  • Dual-Specificity Phosphatases / analysis
  • Dual-Specificity Phosphatases / metabolism
  • Dual-Specificity Phosphatases / physiology*
  • HeLa Cells
  • Humans
  • Kinetochores / metabolism
  • Kinetochores / ultrastructure
  • Mass Spectrometry
  • Mitosis / genetics
  • Mitosis / physiology*
  • Phosphorylation
  • RNA Interference
  • Signal Transduction

Substances

  • Cyclin B
  • Cyclin-Dependent Kinase Inhibitor Proteins
  • CDC2 Protein Kinase
  • CDK1 protein, human
  • Cyclin-Dependent Kinases
  • CDKN3 protein, human
  • Dual-Specificity Phosphatases