Notch signaling can regulate endoderm formation in zebrafish.
Early in vertebrate development, the processes of gastrulation lead to the formation of the three germ layers: ectoderm, mesoderm, and endoderm. The mechanisms leading to the segregation of the endoderm and mesoderm are not well understood. In mid-blastula stage zebrafish embryos, single marginal cells can give rise to both endoderm and mesoderm (reviewed by Warga and Stainier [2002] The guts of endoderm formation. In: Solnica-Krezel L, editor. Pattern formation in zebrafish. Berlin: Springer-Verlag. p 28-47). By the late blastula stage, however, single marginal cells generally give rise to either endoderm or mesoderm. To investigate this segregation of the blastoderm into cells with either endodermal or mesodermal fates, we analyzed the role of Notch signaling in this process. We show that deltaC, deltaD, and notch1 are expressed in the marginal domain of blastula stage embryos and that this expression is dependent on Nodal signaling. Activation of Notch signaling from an early stage leads to a reduction of endodermal cells, as assessed by sox17 and foxA2 expression. We further find that this reduction in endoderm formation by the activation of Notch signaling is preceded by a reduction in the expression of bonnie and clyde (bon) and faust/gata5, two genes necessary for endoderm formation (Reiter et al. [1999] Genes Dev 13:2983-2995; Reiter et al. [2001] Development 128:125-135; Kikuchi et al. [2001] Genes Dev 14:1279-1289). However, activation of Notch signaling in bon mutant embryos leads to a further reduction in endodermal cells, also arguing for a bon-independent role for Notch signaling in endoderm formation. Altogether, these results suggest that Notch signaling plays a role in the formation of the endoderm, possibly in its segregation from the mesoderm.
Kikuchi
Yutaka
Y
Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan. yutaka@cc.nagoya-u.ac.jp
Verkade
Heather
H
Reiter
Jeremy F
JF
Kim
Cheol-Hee
CH
Chitnis
Ajay B
AB
Kuroiwa
Atsushi
A
Stainier
Didier Y R
DY
D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism; D004707:Endoderm / Q000378:metabolism*; D050992:GATA5 Transcription Factor; D005775:Gastrula / Q000378:metabolism; D015870:Gene Expression; D051542:Hepatocyte Nuclear Factor 3-beta; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D055760:SOXF Transcription Factors; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029867:Xenopus Proteins; D015027:Zebrafish / Q000196:embryology* / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D050992:GATA5 Transcription Factor; D006609:High Mobility Group Proteins; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D055760:SOXF Transcription Factors; D014157:Transcription Factors; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C064045:delta protein; C468126:dld protein, zebrafish; C494754:gata5 protein, zebrafish; C499590:mixl1 protein, zebrafish; C491603:sox17 protein, zebrafish; C491602:sox17a protein, Xenopus; C491601:sox17b.1 protein, Xenopus; D051542:Hepatocyte Nuclear Factor 3-beta