2006 Fiscal Year Final Research Report Summary
Studies of molecular mechanisms for proper maturation of secretory proteins
| Project/Area Number |
17370039
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural biochemistry
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| Research Institution | Fukushima Medical University |
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Principal Investigator |
WADA Ikuo Fukushima Medical University, Medicine, Professor (40182969)
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| Co-Investigator(Kenkyū-buntansha) |
HATSUZAWA Kiyotaka Fukushima Medical University, Medicine, Associate Professor (20256655)
HASHIMOTO Hitoshi Fukushima Medical University, Medicine, Assistant Professor (50372826)
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| Project Period (FY) |
2005 – 2006
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| Keywords | endoplasmic reticulum / quality control / secretory system / molecular dynamics / fluorescence correlation spectroscopy |
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| Research Abstract |
Outline of this study to elucidate the molecular mechanisms for protein maturation in the secretory pathway is as follows. 1) Previously, we reported EDEM1 as a factor promoting selective degradation of aberrantly folded glycoproteins. We have now revealed that EDEM3, a soluble protein having similarly in sequence to EDEM1 also stimulates disposal of misfolded proteins in the endoplasmic reticulum. 2) We have shown that calreticulin plays regulatory roles in cell surface expression of CFTR, whose mutation is known to cause cystic fibrosis. 3) We have demonstrated that the endoplasmic reticulum also plays important roles in the process of phagocytosis, presumably by supplying enough amount of membranes during invagination. This issue is highly controversial and, until publication of this report, this hypothesis has been criticized by lack of solid evidences. We have provided evidences showign that ER SNARE protein positively regulates this process. 4) We have shown that EDEM1 prevents aggregation of terminally misfolded proteins while stimulating their disposal. 5) Our mobility analysis of meltrin beta using fluorescence correlation spectroscopy (FCS) indicated that shedding of lumenal domain of neuregulin beta 1 occurs in the Golgi region but not on the cell surface. 6) Sphingomyelinase, an lysosomal enzyme, is known to function in the extracellular space after secretion. We have shown that its efficient secretion is dependent on the presence of a disulfide bond at the carboxyl terminus. 7) By using siRNA library targeting ER proteins, we found more than 10 novel factors required for proper maturation of tyrosinase. 8) We have published our protocols to measure diffusion using FRAP and FCS in living cells.
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