2006 Fiscal Year Final Research Report Summary
Role of Notch signaling in cell fate decision during gastrulation of Xenopus embryo
| Project/Area Number |
17570181
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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 |
Developmental biology
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| Research Institution | Kwansei Gakuin University |
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Principal Investigator |
KINOSHITA Tsutomu Kwansei Gakuin Univ., Sci. & Tech., Prof., 理工学部, 教授 (30161532)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Xenopus laevis / Cell differentiation / Notch signaling / Xoct25 / X1ATF1 |
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| Research Abstract |
Notch signaling in neurogenesis has been studied in detail, whereas Notch signaling in gastrula embryo remains unknown.
1.In order to understand the role of Notch signaling at gastrula stage, we analyzed a function of Xenopus Suppressor of Hairless (XSu(H)) using morpholino oligos (MO). XSu(H)2-MO caused abnormal gastrulation, which resulted in severe defects of the notochord and somitic mesoderm. Studies on the downstream factors of XSu(H)2 showed that gene expression of Xoct25 and 91, Xenopus Oct4 homologues, are regulated by XSu(H)2. Promoter analyses and ChIP assays showed that XSu(H)2 regulates the gene expression of Xoct25 by direct binding to SPS motif on the promoter.
2.In order to understand the role of Mastermind, Xenopus mastermind homologue (XMam1) was injected into ventral marginal zone of 4-cell stage blastomeres. The over-expression of XMam1 in prospective ventral mesoderm caused the excessive cell mass. Injection of XMam1-MO into prospective dorsal mesoderm caused defective gastrulation and head deformity, suggesting that XMam1 is involved in the embryonic axis formation. Experimental results using truncated form of XMam1 and Notch signaling inhibitors showed that XMam1 can induce secondary axis without Notch signaling.
3. In order to understand the role of Notch signaling at gastrula stage, novel Notch target genes were examined by using microarray analysis. The screening identified 11 candidate genes. However, in gain of function experiment, only one gene caused the defective gastrulation. We designated this novel target gene Xenopus ATF1, XATF1. The dominant negative form of XATF1 caused the down-regulation of Xbrachyury and the severe gastrulation defect. Knockdown of XSu(H)2 using morpholino oligo DNA caused the similar defective embryo, which was rescued by co-injection of XATF1.
These results suggest that XSu(H)2 and XMam1 regulate the cell fate in the gastrulation of Xenopus embryo both in Notch-dependent and Notch-independent manner.
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Research Products
(12 results)
