| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2004: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
The chromokinesin Kid/Kinesin-10 is a plus end-directed microtubule (MT)-based motor that binds both MTs and chromosomes during mitosis. It has been revealed that Kid is important in chromosome arm alignment at metaphase plate. In addition, our RNA-interference (RNAi) experiments suggested that Kid also plays other important roles throughout mitosis.
In this study, 1. we performed RNAi experiments to deplete endogenous Kid from HeLa cells and revealed that (1) distinct from its role in chromosome movement, Kid contributes to spindle morphogenesis by mediating spindle microtubules stabilization during prometaphase and metaphase, and that (2) during anaphase, Kid plays a role in connecting adjacent chromosomes to hold individual anaphase chromosomes together during the segregation by acting as a glue able to bind to both MTs and chromosomes. 2. We identified a nuclear import complex as a binding partner of Kid. Our data suggest that the association between import complex and Kid is required for not only nuclear localization during interphase but also Kid's chromosome localization during mitosis. 3. To explore further the physiologic function of Kid, we disrupted the Kid gene in mice and found that the number of Kid-/- offspring as well as Kid-/- E9.5 embryo was about 50% fewer expected, suggesting that Kid plays a critical role during early embryonic development stages. 4. Finally, to explore the kinases that phosphorylate Kid, we examined several mitotic kinases including LATS2. Although we found no obvious biological interaction between Kid and LATS2, we identified LIM protein Ajuba as a binding partner of LATS2. Our results suggest that LATS1-Ajuba complex regulates organization of the spindle apparatus through recruitment of gamma-tubulin to the centrosomes.
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