| Project/Area Number |
17510040
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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 |
Risk sciences of radiation/Chemicals
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| Research Institution | Chiba University |
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Principal Investigator |
KITA Kazuko Chiba University, Graduate School of Medicine, Lecturer, 大学院医学研究院, 講師 (80302545)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Toshikazu Chiba University, Graduate School of Medicine, Research Associate, 大学院医学研究院, 助手 (70270527)
ICHIMURA Yoshinob Chiba University, Graduate School of Medicine, Research Associate, 大学院医学研究院, 助手 (80400993)
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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 | human cells / UV / DNA damage / DNA repair / ER molecular chaperone / GRP78 / sensitivity to cell death / 遺伝子変異誘導 |
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| Research Abstract |
There are only a few reports about the roles of the 78-kDa glucose-regulated protein (GRP78) in human cell response to DNA-damaging stresses. We previously found that GRP78 is involved in resistance to UVC-induced cell death in human cells. We here investigated molecular mechanisms of GRP78-mediated UVC resistance. To investigate whether GRP78 is involved in resistance to a DNA-damaging agent, UVC (principally 254 nm in wavelength), we established human cells with down-regulation of GRP78 by transfection of human RSa cells with antisense cDNA for GRP 78. Using the cells, we found the new findings as below: 1) In the antisense cDNA-transfected cells DNA synthesis activity of whole cell extracts to repair UVC-irradiated plasmids in vitro were remarkably decreased compared with those in the control cells. However, neither addition of recombinant GRP78 protein to the extracts of the former cells recovered the repair synthesis activity, nor depletion of GRP78 from the extracts of the latter cells by immunoprecipitation decreased the activity. 2) The amount of XPA protein was lower in the extracts from the antisene cDNA-transfected cells than from the control cells. 3) GRP78-GFP, expressed in the cultured human cells, localized at perinuclear region. However, the localization did not change remarkably after UVC irradiation. 4) The antisense cDNA-transfected cells showed higher sensitivity to cisplatin-induced cell death, but only slightly higher sensitivity to X-ray-induced cell death than the control cells.
The present results suggest that GRP78 plays a protective role against UVC-induced cell death possibly via nucleotide excision repair (NER), at least in the human RSa cells tested. Molecular mechanisms of the involvement of GRP78 in NER process remain unknown. However, these findings also suggest that GRP78 may not associate directly with repair complex involved the process, but stabilize the NER components or regulate the metabolism of the components in the nucleus.
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