| Project/Area Number |
18591041
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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 | University of Tsukuba |
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Principal Investigator |
MUKAI Harumi University of Tsukuba, Graduate School of Comprehensive Human Science, Assistant Professor (80323301)
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| Co-Investigator(Kenkyū-buntansha) |
MOTOHASHI Hozumi Tohoku University, School of Medicine, Assistant Professor (00282351)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,890,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | megakaryocyte / platelet / transcreption factor / c-Myb / CD9 |
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| Research Abstract |
The nuclear proto-oncogene c-myb plays crucial roles in the growth, survival and differentiation of hematopoietic cells. We established c-myb knock down (KD) mice due to the trangene insertion into 77-kb upstream of the c-myb gene which yielded the reduction of c-Myb expression in megakaryocyte-erythrocyte lineage-restricted progenitors (MEPs). These mice exhibited thrombocythemia, anemia, and splenomegaly. Megakaryopoiesis of c-myb KD mice were extremely increased in both bone marrow and spleen. Previously we showed that these abnormalities were reproducible in vitro in a co-culture assay of MEPs with OP9 cells, but eliminated by the retroviral expression of c-Myb in MEPs. These abnormalities were also reconstituted in mice in vivo through the transplantation of mutant mouse bone marrow cells. To better understand the transcriptional program that accompanies the decline of c-myb gene expression, we performed DNA microarray analysis of MEPs. We identified 74 genes that are upregulated and 36 genes are downregulated in our c-myb mutant mice. Of these genes, expression levels 10 genes are actually changed in bone marrow cells of c-myb mutant mice, and harbor c-Myb recognition elements in the upstream region. The expression levels of CD9 and Ly6a were increased in bone marrow cells of c-myb mutant mice and we revealed their interaction with c-Myb using chromatin immunopretipitaion assay. Agonistic antibodies of CD9 and Ly6a stimulated megakaryocytic colony formation in number and especially in size with the agonistic CD9 antibody. These results thus demonstrate that the reduced expression of c-myb gene affects as the stimulator of megakaryopoiesis and both CD9 and Ly6a were candidates of c-Myb target gene. Elucidation of transcription network based on the c-myb gene on megakaryopoiesis will take a new turn of lineage specific regulation.
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