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WARTS tumor suppressor is phosphorylated by Cdc2/cyclin B at spindle poles during mitosis
Tetsuro Morisaki1, Toru Hirota, Shin-ichi Iida
1Department of Tumor Genetics and Biology, Kumamoto University School of Medicine, 2-2-1 Honjo, Kumamoto 860-0811, Japan.
Abstract:
Identification of physiological substrates for Cdc2/cyclin B is crucial for understanding the functional link between mitotic events and Cdc2/cyclin B activation. A human homologue of the Drosophila warts tumor suppressor, termed WARTS, is a serine/threonine kinase and a dynamic component of the mitotic apparatus. We have found that Cdc2/cyclin B forms a complex with a fraction of WARTS in the centrosome and phosphorylates the Ser613 site of WARTS during mitosis. Immunocytochemical analysis has shown that the S613-phosphorylated WARTS appears in the spindle poles at prometaphase and disappears at telophase. Our findings suggest that Cdc/cyclin B regulates functions of WARTS on the mitotic apparatus.