| Project/Area Number |
17390141
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Immunology
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| Research Institution | International Medical Centre of Japan (Research Institute) (2006)
The University of Tokyo (2005) |
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Principal Investigator |
TAKAKI Satoshi International Medical Center ofJapan (Research Institute), Department of Community Health and Medicine, Director, 地域保健医療研究部, 部長 (10242116)
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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 |
¥14,200,000 (Direct Cost: ¥14,200,000)
Fiscal Year 2006: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 2005: ¥9,600,000 (Direct Cost: ¥9,600,000)
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| Keywords | Immunology / B cell development / Signal transduction / Regenerative medicine / Infectious disease / Transplantation / Transcription factor / Bone marrow transfer / アダプター蛋白質 / リンパ球 |
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| Research Abstract |
Lnk consists of an N-terminal proline-rich region, PH-, SH2-domains and a tyrosine phosphorylation site. We showed that Lnk may control actin reorganization and regulates cell mobility. Lnk expressing fibroblasts showed flattened, spreading shapes and prominent actin polymerization. CXCL12-induced transwell migration of splenic B cells was significantly enhanced by serum stimulation in lnk-/-B cells but not in the wild-type B cells. Our result revealed a novel function of Lnk as a protein linking growth factor receptors with cytoskeletal regulatory components, and as a regulator of cell migration or adhesion under the control of growth factors.
Formation of the PreBCR complex is a critical checkpoint during B cell development and induces the transition of ProB to PreB cells. ProB cells from RAG2/Btk-double KO (DKO) mice did not differentiate into PreB cells following Ig β cross-linking, indicating that Btk is indispensable for the transition. In order to identify genes involved in differentiation signaling downstream of Btk, we analyzed mRNA expression in B precursor cells from RAG2-KO or RAG2/Btk-DKO mice after Ig β cross-linking by GeneChip analysis. Genes that were up-or down-regulated in RAG2 KO B precursors but not in RAG2/Btk DKO precursors were selected. Functions of those candidate genes were evaluated by their enforced expression using retrovirus vector and genes that promoted transition from ProB to PreB cells were identified.
Hematopoietic stem/progenitor cells (HSC/Ps) lacking Lnk show an enhanced repopulating ability in a competitive repopulation assay. We identified functional domains of Lnk critical for the inhibitory effects that were completely abolished by a point mutation in the SH2 domain. Those SH2 Lnk mutants acted as dominant-negative (DN) mutants, and inhibited functions of Lnk endogenously expressed in HSC/Ps. HSC/Ps expressing DN Lnk by retroviral transduction or by electroporation showed facilitated repopulation in irradiated host animals.
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