| Budget Amount *help |
¥4,110,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥510,000)
Fiscal Year 2007: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2006: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
In the cell nucleus, many important events including gene transcription, replication, repairs occur under complicated regulations. Nuclear factors are not randomly or evenly distributed within the nucleus, rather they are highly and dynamically compartmentalized into several domains, which enables many reactions to be rapid and efficient in the nucleus. Goal of this project is to elucidate the mechanism of how SUMOylation regulates the nucleus. I designed and performed following experiments.
SUMOylation by RanBP2 plays a role in nuclear domain formations.
With in situ SUMOylation assay that visualizes sub-cellular localization of SUMOylation activity, I showed that RanBP2 exerts SUMO E3 activity at the nuclear pore complex. By knockdown of RanBP2 by siRNA, SUMOylation activity at the nuclear pore complex was lost, together with several changes in nuclear domains, such as reduction of numbers of PML bodies and aberrant forms of nuclear speckles. A novel model was suggested, in which proteins are SUMOlyated at the nuclear pore complex by RanBP2, when they are transported from cytoplasm to the nucleus.
Function of nuclear speckle and the mechanism for its formation.
Nuclear speckle contains many factors for transcription, RNA processing, transport and so on and thus it is involved in gene expression regulation. I analyzed changes in gene expression patterns and localizations of nuclear speckle components in RanBP2 knockdown cells in which nuclear speckles are aberrantly formed. The study presents one of the first molecularly tractable pathways for establishing nuclear architecture. In summary, I revealed significant role of SUMOylation in nuclear domain formations, and made contributions to understand function and dynamics of the cell nucleus.
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