| Budget Amount *help |
¥15,500,000 (Direct Cost: ¥15,500,000)
Fiscal Year 2006: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 2005: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 2004: ¥6,300,000 (Direct Cost: ¥6,300,000)
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| Research Abstract |
Cell polarity is coordinately regulated during cell cycle and is important for cellular function of individual cells. In this research, we studied a novel checkpoint monitoring growth polarity in yeast. Our findings are as follows.
1) Activation of cell morphogenesis checkpoint by ethanol: We have analyzed the effect of ethanol on cell morphology of yeast and found that ethanol disrupts actin-cytoskeleton transiently and induces the delay in G2. This result indicated that ethanol activates cell morphogenesis checkpoint in yeast.
2) Morphogenesis network from SPB: In fission yeast, the conserved proteins, MO25-like Pmo25, GC kinase Nak1, Mor2, and Orb6, constitute a morphogenesis Orb6 network (MOR) for polarity control and cell separation. Pmo25 was localized at the mitotic spindle pole bodies (SPBs) and then underwent translocation to the dividing medial region upon cytokinesis. Pmo25 formed a complex with Nakl and was required for Nakl-Orb6 kinase activity. Further, the Pmo25 localizati
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on at the SPBs and the Nakl-Orb6 kinase activities during interphase were under the control of the Cdc7 and Sidl kinases in the septation initiation network (SIN), suggesting a functional linkage between SIN and MOR for cell morphogenesis/separation following cytokinesis.
3) Activation of the Bubl-dependent checkpoint by а-tubulin mutation: We have identified a novel temperature-sensitive mutant of fission yeast a-tubulin Atb2 (atb2-983) that contains a single amino acid substitution (V260I). Atb2-983 is incorporated into the microtubules, and their overall structures are not altered noticeably, but microtubule dynamics is compromised during interphase. The results indicate that the V260I mutation affects microtubule dynamics and EB1-Mal3 localization and activates the Bubl branch of the spindle checkpoint.
4) Image processing programs for accurate measurement of yeast morphology: To describe yeast morphology objectively, we have developed image processing programs for budding and fission yeast. Using this program, we can easily and quickly obtain various quantitative data reproducibly. Less
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