2007 Fiscal Year Final Research Report Summary
Analysis of Cbl-mediated signal transduction involved in proliferation of leukemia cells and application to treatment of leukemia
| Project/Area Number |
18591068
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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 |
Hematology
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| Research Institution | Kagawa University |
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Principal Investigator |
KUBOTA Yoshitsugu Kagawa University, Faculty of Medicine, associated professor (90178054)
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| Co-Investigator(Kenkyū-buntansha) |
KITANAKA Akira Kagawa University, Faculty of Medicine, assistant professor (70343308)
OHNISHI Hiroaki Kagawa University, Faculty of Medicine, Associated Professor (90223891)
TANAKA Terukazu Kagawa University, Faculty of Medicine, professor (20155146)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Cbl / erythropoietin / leukemia / PI3-kinase / signal transduction / Src / ubiquitine |
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| Research Abstract |
Cbl functions as the ubiquitine ligase and adaptor molecule in a variety of receptor-mediated signaling. However, the function of Cbl in erythropoietin receptor (EPOR)-mediated signaling is still unidentified. In the present study, to examine a physiological function of Cbl in EPOR-mediated signaling, we developed Cbl-deficient F-36P human erythroleukemia (F-36P-Cbl-siRNA) cells by introducing the expression vector for Cbl siRNA. Knockdown of Cbl induced enhancement of proliferation and survival of F-36P cells at a physiological concentration of EPO compared to that of mock-transfected F-36P (F-36P-mock) cells. Furthermore, apoptosis of F-36P-Cbl-siRNA was decreased in the absence of EPO compared to that of F-36P-mock cells. We next examined the mechanism by which Cbl inhibits proliferation of F-36P cells and promotes survival of those cells. Akt was constitutively activated in F-36P-Cbl-siRNA but not in F-36P-mock cells. Knockdown of Cbl did not affect EPO-induced activation of Erk1/2
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in F-36P cells. After EPO treatment, Cbl was phosphorylated on tyrosine residues including Tyr731, a binding site for the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3-kinase) and associated with p85. EPO-induced phosphorylation of Cbl on Tyr731 in F-36P cells was inhibited by PP1, a selective Src kinase inhibitor, but not by AG490, a selective Jak kinase inhibitor. In F-36P cells expressing the dominant-negative Src, EPO failed to induce the tyrosine phosphorylation of Cbl. Co-expression experiments, In vitro kinase and GST pull-down assays further demonstrated that recombinant Src directly phosphorylated Cbl on Tyr731. Taken together with these findings, Cbl negatively regulates EPO-induced proliferation and survival of F-36P cells through the PI3-kinase/Akt pathway. In addition, Src is likely to be involved in Cbl-mediated regulation of PI3-kinase through inducing association of Cbl with p85, because Src phosphorylates Cbl on Tyr731, thereby leading to providing a binding site for p85. Less
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Research Products
(4 results)
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[Presentation] Gabl Is Involved in Erythropoietin Receptor-Mediated Survival Signal throughActivation of the Erk Pathway2007
Author(s)
Tetsuya, Fukumoto, Yoshitsugu, Kubota, Akira, Kitanaka, Fusako, Waki, Osamu, Imataki, Hiroaki, Ohnishi, Toshihiko, Ishida, Terukazu, Tanaka
Organizer
49th American Society of Hematology
Place of Presentation
Atlanta
Year and Date
2007-12-09
Description
「研究成果報告書概要(欧文)」より
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[Presentation] Src-dependent phosphorylation of Cbl in erythropoietin receptor-mediated Signal transduction2006
Author(s)
Yoshitsugu, Kubota, Tetsuya, Fukumoto, Akira, Kitanaka, Hiroaki, Ohnishi, Hiroshi, Kamano, Toshihiko, Ishida, Terukazu, Tanaka
Organizer
The 68th Annual Meeting of the Japanese Society of Hematology and the 48th Annual Meeting of the Japanese Society of Clinical Hematology
Place of Presentation
Fukuoka
Year and Date
2006-10-07
Description
「研究成果報告書概要(欧文)」より
