| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
It is well known that some members of Ets family transcription factors and homeodomain proteins play important roles in hematopoiesis. There are, however, few reports showing their direct interactions. In this study, we examined physical and functional interactions of these proteins.
Luciferase assay using a reporter construct with Ets-binding site showed that homeodomain proteins, HoxA10 and HoxC13, enhanced transcription activities of Ets family transcription factors, PU.1 and Spi-B, and reduced those of Elf-1,Erg-3,Ets-2. It also showed that Meis1 reduced transcription activities of Ets-1 and Ets-2.
We then focused on examining physical interactions between HoxC13 and PU.1 or Elf-1 because the former is known to be involved in chromosome translocation in human leukemias and the latter two in generation of both of myeloid and lymphoid lineages. Immunoprecipitation assay showed that HoxC13 bound to PU.1 or Elf-1 in 293T cells. Further, GST pull-down assay using deletion mutants of these proteins indicated that HoxC13 bound to PU.1 or Elf-1 via C-terminal-half of its homeodomain and PU.1 bound to HoxC13 via its Ets domain. Moreover, mutant form of HoxC13, truncating Ets factor-binding domain, showed neither synergistic nor antagonistic effects on transcription activity of PU.1 and Elf-1, respectively, suggesting that the physical interactions of these proteins are essential for their functional interactions.
In the course of DMSO-mediated erythroid differentiation of murine erythroleukemia cells, expression levels of the PU.1 and HoxC13 genes were downregulated while that of the Elf-1 gene was upregulated.
Taken together, these results suggest that some of Ets family transcription factors and homeodomain proteins interact physically and functionally and that the interaction play some roles in hematopoiesis.
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