Abstract
During G2 phase of cell cycle, centrosomes function as a scaffold for activation of mitotic kinases. Aurora-A is first activated at late G2 phase at the centrosome, facilitates centrosome maturation, and induces activation of cyclin B-Cdk1 at the centrosome for mitotic entry. Although several molecules including HEF1 and PAK are implicated in centrosomal activation of Aurora-A, signaling pathways leading to Aurora-A activation at the centrosome, and hence mitotic commitment in vertebrate cells remains largely unknown. Here, we have used Clostridium difficile toxin B and examined the role of Rho GTPases in G2/M transition of HeLa cells. Inactivation of Rho GTPases by the toxin B treatment delayed by 2 h histone H3 phosphorylation, Cdk1/cyclin B activation, and Aurora-A activation. Furthermore, PAK activation at the centrosome that was already present before the toxin addition was significantly attenuated for 2 h by the addition of toxin B, and HEF1 accumulation at the centrosome that occurred in late G2 phase was also delayed. These results suggest that Rho GTPases function in G2/M transition of mammalian cells by mediating multiple signaling pathways converging to centrosomal activation of Aurora-A.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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ADP Ribose Transferases / pharmacology
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Adaptor Proteins, Signal Transducing / metabolism
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Amides / pharmacology
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Aurora Kinases
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Bacterial Proteins / pharmacology*
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Bacterial Toxins / pharmacology*
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Botulinum Toxins / pharmacology
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CDC2 Protein Kinase / metabolism
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Centrosome / drug effects*
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Centrosome / enzymology*
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Cyclin B / metabolism
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Cytochalasin D / pharmacology
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Enzyme Activation / drug effects
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G2 Phase / drug effects*
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HeLa Cells
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Histones / metabolism
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Humans
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Mitosis / drug effects*
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Models, Biological
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Phosphoproteins / metabolism
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Phosphorylation / drug effects
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Phosphoserine / metabolism
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Protein Serine-Threonine Kinases / metabolism*
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Protein Transport / drug effects
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Pyridines / pharmacology
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p21-Activated Kinases / metabolism
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rho GTP-Binding Proteins / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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Amides
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Bacterial Proteins
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Bacterial Toxins
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Cyclin B
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Histones
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NEDD9 protein, human
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Phosphoproteins
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Pyridines
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toxB protein, Clostridium difficile
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Y 27632
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Phosphoserine
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Cytochalasin D
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ADP Ribose Transferases
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exoenzyme C3, Clostridium botulinum
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Aurora Kinases
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Protein Serine-Threonine Kinases
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p21-Activated Kinases
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CDC2 Protein Kinase
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Botulinum Toxins
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rho GTP-Binding Proteins