| Project/Area Number |
17590083
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biological pharmacy
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| Research Institution | The Institute of Physical and Chemical Research |
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Principal Investigator |
MATSUMOTO Ken The Institute of Physical and Chemical Research, Cellular Biochemistry Laboratory, Senior Research scientist (60222311)
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| Co-Investigator(Kenkyū-buntansha) |
TSUJIMOTO Masafumi RIKEN, Cellular Biochemistry Laboratory, Chief scientist (00281668)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | mRNA / translational control / ribonucleonrotein narticle / Xenonus / P-body |
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| Research Abstract |
Cytoplasmic mRNPs are substrates of the translational apparatus in eukaryotic cells. The poly(A) binding protein and the Y-box protein YB-1 are common major components of cytoplasmic mRNPs in somatic cells of different organisms. Y-box proteins are presumed to bind to the mRNA body in the cytoplasmic mRNPs and are likely responsible for packaging of mRNAs into mRNPs. Y-box proteins are also implicated in translational masking of maternal and paternal mRNAs in germ cells. Regulation of the availability of Y-box proteins in cells would have an influence on mRNA metabolism and the control of cell proliferation.
By immunoprecipitation of the epitope-tagged Y-box proteins expressed in somatic cells or Xenopus oocytes, we have isolated Y-box protein-associated RNPs. Protein components of these RNPs include the poly(A) binding protein, a DEAD-box ATPase (RCK/p54 in mammals or Xp54 in Xenopus) and a number of RNA binding proteins. Among these, we identified Xenopus RAP55 (xRAP55) as a component of maternal mRNPs. Recombinant xRAP55 repressed translation, together with Xp54, in an in vitro translation system. In addition, xRAP55 repressed translation in oocytes when tethered with a reporter mRNA. RAP55 and the Y-box proteins localized to cytoplasmic foci in Xenopus oocytes and the processing bodies (P-bodies) in cultured human cells. Interestingly, upon heat stress, whereas RAP55 and RCK were detected both in the P-bodies and stress granules (SGs), YB-1 was accumulated in SGs and almost excluded from the P-bodies. Our results suggest that remodeling of mRNP would take place when mRNAs move between these cytoplasmic structures.
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