| Project/Area Number |
08557036
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
内科学一般
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MORIMOTO Chikao The University of Tokyo Institute of Medical Science Professor, 医科学研究所, 教授 (30119028)
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| Co-Investigator(Kenkyū-buntansha) |
HOMMA Toshio The University of Tokyo Institute of Medical Science Research Associate, 医科学研究所, 教務職員 (10282526)
HOSONO Osamu The University of Tokyo Institute of Medical Science Research Associate, 医科学研究所, 助手 (50190210)
KAWASAKI Hiroshi The University of Tokyo Institute of Medical Science Research Associate, 医科学研究所, 助手 (80280957)
NOJIMA Yoshihisa Gunma University school of Medicine Associate Professor, 医学部, 助教授 (90201699)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥15,900,000 (Direct Cost: ¥15,900,000)
Fiscal Year 1997: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1996: ¥12,500,000 (Direct Cost: ¥12,500,000)
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| Keywords | CD26 / Dipeptidyl peptidase IV / Adenosine deaminase / Costimulatory molecule / adenosine / Dipeptidyl peptidase IV / costimylatory分子 / ADA結合蛋白 / co-stimulatory分子 / CD3 / TCR複合体 |
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| Research Abstract |
CD26, a 110-KDa cell surface glycoprotein, exhibits dipeptidyl peptidase IV (DPPIV) enzyme activity and plays an important role in T cell costimulation. We previonsly demonstrated that CD26 is directly associated with adenosine deaminase (ADA) and that cells expressing ADA and CD26 on the surface were much more resistant to the inhibitory effect of adenosine, suggesting that ADA on the cell surface via CD26 appears to overcome the inhibitory effect of the elevated extracellular adenosine. However, previous studies have not yet determined whether there is a specific ADA binding domain on CD26, whether the interaction of ADA and CD26 on the cell surface has a direct immunoregulatory effecton T cell activation, and whether CD26 on the cell surface involves resistance to the inhibitory effect of adenosine.
We found that the residues of Leucine_<340>, Valine_<341>, Alanine_<342>and Arginine_<343> on the CD26 molecule were essential amino acids for ADA binding. When these amino acids were mutated and transfected into Jurkat cells, the resultant CD26 transfectants expressed only CD26, not ADA,on the cell surface. The amount of IL-2 produced by wild-type and mutated CD26 transfectants was almost the same following stimulation with anti-CD3 plus PMA.However, the mutated CD26 transfectants were much more sensitive to the inhibitory effect of adenosine on IL-2 production than were the wild CD26 transfectants. These data suggest that ADA on the cell surface does not directlyinvolve T cell activation. Conversely, CD26 alone does not result in modulating the inhibitory effect of adenosine. Only the ADA bound to CD26 on the cell surface was functional and could counteract the inhibitory effect of elevated extracellular adenosine.
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