First published online March 6, 2009
Development 136, 703e (2009)
© The Company of Biologists Limited
Throw a Six3 for neurogenesis
In sea urchin embryos, Wnt and Nodal signalling centres initiate patterning
along the primary and secondary axes, respectively. Now, on
p.1179, Lynne Angerer
and colleagues characterise a third, neurogenic patterning centre, the animal
pole domain (APD). By investigating the gene regulatory network acting in the
sea urchin APD, the researchers discover that the transcription factor Six3 is
required for the expression of most of the regulatory genes expressed early in
this domain. Six3 is necessary, they report, for the development of the APD
and all neurons and is sufficient to suppress Nodal and Wnt signals and to
respecify nearly all the cells in the embryo to form an enlarged but
appropriately patterned APD. Thus, the APD is a Six3-dependent neurogenic
patterning centre in sea urchin embryos and, the researchers suggest, because
many Six3-dependent regulatory genes are orthologous to genes expressed in the
developing vertebrate forebrain, certain components of the gene regulatory
network that regulates neurogenesis may have originated in the common ancestor
of echinoderms and vertebrates.

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Related articles in Development:
- The sea urchin animal pole domain is a Six3-dependent neurogenic patterning center
- Zheng Wei, Junko Yaguchi, Shunsuke Yaguchi, Robert C. Angerer, and Lynne M. Angerer
Development 2009 136: 1179-1189.
[Abstract]
[Full Text]