Rac1-dependent recruitment of PAK2 to G2 phase centrosomes and their roles in the regulation of mitotic entry

Cell Cycle. 2014;13(14):2211-21. doi: 10.4161/cc.29279. Epub 2014 May 19.

Abstract

During mitotic entry, the centrosomes provide a scaffold for initial activation of the CyclinB/Cdk1 complex, the mitotic kinase Aurora A, and the Aurora A-activating kinase p21-activated kinase (PAK). The activation of PAK at the centrosomes is yet regarded to happen independently of the Rho-GTPases Rac/Cdc42. In this study, Rac1 (but not RhoA or Cdc42) is presented to associate with the centrosomes from early G2 phase until prometaphase in a cell cycle-dependent fashion, as evidenced by western blot analysis of prepared centrosomes and by immunolabeling. PAK associates with the G2/M-phase centrosomes in a Rac1-dependent fashion. Furthermore, specific inhibition of Rac1 by C. difficile toxinB-catalyzed glucosylation or by knockout results in inhibited activation of PAK1/2, Aurora A, and the CyclinB/Cdk1 complex in late G2 phase/prophase and delayed mitotic entry. Inhibition of PAK activation at late G2-phase centrosomes caused by Rac1 inactivation coincides with impeded activation of Aurora A and the CyclinB/Cdk1 complex and delayed mitotic entry.

Keywords: Aurora; C. difficiletoxin B; Cdc42; Cdk1; CyclinB; Rho; mono-O-glucosylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aurora Kinase A / metabolism
  • Bacterial Proteins / pharmacology
  • Bacterial Toxins / pharmacology
  • CDC2 Protein Kinase
  • Centrosome / enzymology*
  • Cyclin B / metabolism
  • Cyclin-Dependent Kinases / metabolism
  • Enzyme Activation
  • G2 Phase Cell Cycle Checkpoints* / drug effects
  • Glycosylation
  • HeLa Cells
  • Humans
  • Mice
  • Mitosis* / drug effects
  • Neuropeptides / antagonists & inhibitors
  • Neuropeptides / genetics
  • Neuropeptides / metabolism
  • RNA Interference
  • Signal Transduction
  • Time Factors
  • Transfection
  • p21-Activated Kinases / genetics
  • p21-Activated Kinases / metabolism*
  • rac1 GTP-Binding Protein / antagonists & inhibitors
  • rac1 GTP-Binding Protein / genetics
  • rac1 GTP-Binding Protein / metabolism*

Substances

  • Bacterial Proteins
  • Bacterial Toxins
  • Cyclin B
  • Neuropeptides
  • RAC1 protein, human
  • Rac1 protein, mouse
  • toxB protein, Clostridium difficile
  • AURKA protein, human
  • Aurora Kinase A
  • PAK2 protein, human
  • Pak2 protein, mouse
  • p21-Activated Kinases
  • CDC2 Protein Kinase
  • CDK1 protein, human
  • Cyclin-Dependent Kinases
  • rac1 GTP-Binding Protein