2002 Fiscal Year Final Research Report Summary
The analysis of dharma/bozozok gene function in vertebrates body axis formation.
| Project/Area Number |
13670013
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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 |
General anatomy (including Histology/Embryology)
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| Research Institution | RIKEN (2002)
Osaka University (2001) |
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Principal Investigator |
SHIMIZU Takashi RIKEN Laboratory for vertebrate axis formation Research scientist, 体軸形成研究チーム, 研究員 (50324760)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Organizer / Wnt / dhama / bozozok / Homeobox / Transcriptional repressor / vox / vent / ved / Axis formation |
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| Research Abstract |
Specification of dorso-ventral body axis requires the maternally-derived Wnt signal activation. The maternally-derived Wnt signal activates genes that are involved in formation of the Nieuwkoop center and subsequently induction of the dorsal organizer. The homeobox gene dharma/bozozok (dha/boz) is a direct target gene of the maternal Wnt signal and plays an important role in the formation and/or function of the zebra fish dorsal organizer. Dha/Boz contains an amino acid motif similar to the repressor domain of Engrailed (Ehl motif). We found that Dha/Boz interacted with a co-repressor Groucho through the Eh1 motif. The repressor activity of Dha/Boz was required for expression of organizer genes and dha/boz-dependent dorsalization of the embryos. By ordered differential display method, we isolated a novel ventrally-expressed homeobox gene ved, which displays sequence similarities with vox and vent, ved is a target of the transcriptional repressors Dha/Boz. The analysis of transcriptional activator and repressor domain fusion proteins suggested that Ved acts as a transcriptional repressor. By antisense morpholino-mediated loss of function experiments, we showed that ved, vox and vent were redundant repressors of the dorsal organizer formation. These results suggested that dha/boz promoted the dorsal fate by suppressing the expression of ved, vox, and vent which act to restrict the expression of the dorsal organizer genes in appropriate region.
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