Rac1-dependent recruitment of PAK2 to G2 phase centrosomes and their roles in the regulation of mitotic entry.
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.
Institute of Toxicology; Hannover Medical School; Hannover, Germany.
Martin
M
May
Institute of Toxicology; Hannover Medical School; Hannover, Germany.
Ilona
I
Schelle
Biomedical Institute; University of Copenhagen; Copenhagen, Denmark.
Cord
C
Brakebusch
Division of Molecular Cell Biology; Zoological Institute; Technical University Braunschweig, Germany; Helmholtz Centre for Infection Research; Braunschweig, Germany.
Klemens
K
Rottner
Institute of Toxicology; Hannover Medical School; Hannover, Germany.
Harald
H
Genth
D000818:Animals; D064096:Aurora Kinase A / Q000378:metabolism; D001426:Bacterial Proteins / Q000494:pharmacology; D001427:Bacterial Toxins / Q000494:pharmacology; D016203:CDC2 Protein Kinase; D018385:Centrosome / Q000201:enzymology*; D019926:Cyclin B / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004789:Enzyme Activation; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D006031:Glycosylation; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008938:Mitosis / Q000187:drug effects; D009479:Neuropeptides / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D054462:p21-Activated Kinases / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D019926:Cyclin B; D009479:Neuropeptides; C107953:RAC1 protein, human; C484602:Rac1 protein, mouse; C031815:toxB protein, Clostridium difficile; C576917:AURKA protein, human; D064096:Aurora Kinase A; C515907:PAK2 protein, human; C515909:Pak2 protein, mouse; D054462:p21-Activated Kinases; D016203:CDC2 Protein Kinase; C528899:CDK1 protein, human; D018844:Cyclin-Dependent Kinases; D020830:rac1 GTP-Binding Protein
Aurora; C. difficiletoxin B; Cdc42; Cdk1; CyclinB; Rho; mono-O-glucosylation