title: Inactivation of Rho GTPases with Clostridium difficile toxin B impairs centrosomal activation of Aurora-A in G2/M transition of HeLa cells.
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.
authors.affiliation: Department of Pharmacology and Horizontal Medical Research Organization, Kyoto University Faculty of Medicine, Kyoto 606-8501, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ando
authors.forename: Shingo
authors.initials: S
authors.lastname: Yasuda
authors.forename: Fabian
authors.initials: F
authors.lastname: Oceguera-Yanez
authors.forename: Shuh
authors.initials: S
authors.lastname: Narumiya
mesh_terms: D036002:ADP Ribose Transferases / Q000494:pharmacology; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D064127:Aurora Kinases; D001426:Bacterial Proteins / Q000494:pharmacology*; D001427:Bacterial Toxins / Q000494:pharmacology*; D001905:Botulinum Toxins / Q000494:pharmacology; D016203:CDC2 Protein Kinase / Q000378:metabolism; D018385:Centrosome / Q000187:drug effects* / Q000201:enzymology*; D019926:Cyclin B / Q000378:metabolism; D015638:Cytochalasin D / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D016195:G2 Phase / Q000187:drug effects*; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D008938:Mitosis / Q000187:drug effects*; D008954:Models, Biological; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D054462:p21-Activated Kinases / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000577:Amides; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D019926:Cyclin B; D006657:Histones; C099942:NEDD9 protein, human; D010750:Phosphoproteins; D011725:Pyridines; C031815:toxB protein, Clostridium difficile; C108830:Y 27632; D010768:Phosphoserine; D015638:Cytochalasin D; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D016203:CDC2 Protein Kinase; D001905:Botulinum Toxins; D020741:rho GTP-Binding Proteins