First published online April 12, 2006
Development 133, 905e (2006)
© The Company of Biologists Limited
New dimensions for Shh
The mid/hindbrain is an excellent model for studying 3D tissue patterning,
but although its anteroposterior (AP) patterning is well characterised,
dorsoventral (DV) patterning is not. Now, Blaess et al. (p.
1799) have used
conditional mutagenesis to investigate how sonic hedgehog (Shh) directs DV
patterning. Shh has two signalling modes involving the Gli transcription
factors: in Gli2A-mediated Shh signalling, Shh converts Gli2 into a
transcriptional activator; and in Gli3R-mediated Shh signalling, Shh opposes
the processing of Gli3 into a repressor. The authors conditionally removed all
Shh signalling (by mutating the receptor Smo) or just Gli2A-mediated
Shh signalling (by mutating Gli2) at E9.0 or at E11.5 in the mouse
mid/hindbrain. Gli2A-mediated signalling was needed early on for ventral
patterning and for the dorsal restriction of Gli3 transcription.
Gli3R-mediated signalling was important throughout for the development of
dorsal structures and before E11 for regulating growth by inhibiting
apoptosis. Gli3R-mediated Shh signalling also regulated the expression of the
AP organiser Fgf8, leading the authors to conclude that Shh coordinates the AP
and DV patterning of the developing mid/hindbrain.

CiteULike
Complore
Connotea
Del.icio.us
Digg
Reddit
Technorati
Twitter What's this?
Related articles in Development:
- Sonic hedgehog regulates Gli activator and repressor functions with spatial and temporal precision in the mid/hindbrain region
- Sandra Blaess, JoMichelle D. Corrales, and Alexandra L. Joyner
Development 2006 133: 1799-1809.
[Abstract]
[Full Text]