| Project/Area Number |
07044301
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Tokyo Metropolitan Institute for Neuroscience |
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Principal Investigator |
YAKURA Hidetaka Tokyo Metropolitan Institute for Neuroscience, 微生物学・免疫学, 参事 (60166486)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUNO Kazuya Tokyo Metropolitan Institute for Neuroscience, 微生物・免疫, 副参事 (00219643)
KATAGIRI Tatsuo Tokyo Metropolitan Institute for Neuroscience, 微生物・免疫, 主事 (00233742)
OGIMOTO Mami Tokyo Metropolitan Institute for Neuroscience, 微生物・免疫, 主事 (80158609)
KORETZKY Gary University of Iowa College of Medicine, 医学部・内科学, 準教授
GARY Koretzk アイオワ大学医学部, 内科学, 準教授
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥7,600,000 (Direct Cost: ¥7,600,000)
Fiscal Year 1996: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 1995: ¥3,800,000 (Direct Cost: ¥3,800,000)
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| Keywords | CD45 / Apoptosis / SHP-1 / SLP-76 / HCP |
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| Research Abstract |
This project was initiated to elucidate the mechanisms whereby CD45 regulates antigen receptor (BCR)-mediated positive and negative signaling at immature and mature B cell differentiation. For this project, CD45-negative clones were generated from the immature WEHI-231 and the mature BAL-17 B cell lines.
As a first step toward the elucidation of CD45-initiated signaling events, we have tried to identify physiological substrates for CD45 by analyzing PTK activity in CD45-deficient clones from WEHI-231. The results demonstrated that among PTKs examined (Lyn, Lck, and Syk), only Lyn kinase is dysregulated in the absence of CD45 such that Lyn is hyperphosphorylated and activated in CD45-negative clones without BCR ligation. Thus, Lyn seems to be a selective in vivo substrate for CD45 in immature B cells. lyn seems to be negatively regulated by CD45 in WEHI-231 cells. The mode of CD45 action on Lyn is currently under study.
In contrast, BCR-initiated tyrosine phosphorylation of CD45-negative
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clones from BAL-17 was only slightly reduced, but a protein of about 60 kDa was not tyrosine phosphorylated without CD45. These results suggest that positive regulation is exerted by CD45 in mature B cells and that an unphosphorylated protein of 60 kDa may be a substrate for CD45 in mature B cells. We are in the process of examining this possibility.
We also examined mechanisms of action of SHP-1, an SH2-containing tyrosine phosphatase involved in negative regulation of B cells. We first searched for proteins that interact with SHP-1. Both anti-SHP-1 Ab and the two SH2 domains of SHP-1-GST fusion proteins precipitated three phosphoproteins (75 kDa, 110 kDa, and 150 kDa) upon anti-IgM stimulation of WEHI-231. Immunoprecipitation and Western blot analysis revealed that the SHP-1-associated 75-kDa protein is the hematopoietic cell-specific, SH2-containing protein SLP-76 and that this protein-protein association was constitutively observed. The nature of other SHP-1-binding proteins is under investigation. Less
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