1997 Fiscal Year Final Research Report Summary
Identification of Proteins Associated with the Intracellular Degradation of Misfolded Clotting Factors
| Project/Area Number |
08680698
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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 |
Functional biochemistry
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| Research Institution | Himeji Institute of Technology |
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Principal Investigator |
TOKUNAGA Fuminori Himeji Institute of Technology, Science, Assistant, 理学部, 助手 (00212069)
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| Co-Investigator(Kenkyū-buntansha) |
KOIDE Takehiko Himeji Institute of Technology, Science, Professor, 理学部, 教授 (60018695)
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| Project Period (FY) |
1996 – 1997
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| Keywords | quality control / proteasome / chaperone / gamma-carboxylation / protein C / prothrombin / warfarin / endoplasmic reticulum |
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| Research Abstract |
We have shown that the vitamin K-dependent coagulation factors synthesized in the presence of warfarin, an oral anticoagulant, is degraded intracellularly through the quality control mechanism in the endoplasmic reticulum (ER). this is a sole model for the drug-induced ER-associated degradation. On 1996, We identified that intracellular protein C synthesized in the presence of warfarin was associated with ER molecular chaperones such as GRP94, GRP78(BiP), and calreticulin on the course of intracellular degradation. Moreover, proteasomal inhibitors such as lactacystin and Z-leu-Leu-Leu-H inhibited the warfarin-induced degradation of protein C,suggesting that under-gamma-carboxylated protein C is Degraded by proteasome in cytosol through the retrograde transport. On 1997, We compared the warfarin-sensitivity among vitamin K-dependent proteins. Protein C synthesized in HepG2 cells was extensively degraded in the presence of warfarin, whereas-50% of prothrombin was secreted into medium. This results suggested that prothrombin Gla domain is moro resistant to warfarin than that of protein C.Then, we constructed two chimeras of protein C having prothrombin Gla domain (GDII/PC) and having prepro-sequence to Gladomain of prothrombin (PPGDII/PC), and examined the secretion of chimeras using BHK cells. Unexpectedly, both chimeric proteins were not secreted even in the presence of vitamin K.gamma-Carboxylation of chimeras was occurred normally. These results suggested that not only gamma-carboxylation in the Gla domain, but the interaction of certain Gla domain to other domains is also an important factor in quuality control of vitamin K-dependent proteins.
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