First published online October 27, 2004
Development 131, 2203e (2004)
© The Company of Biologists Limited
Sonic hedgehog signals brain shape
The species-specific pattern of lobes or folia in the mammalian cerebellum
is largely generated postnatally during the expansion of the granule cell
precursor (GCP) pool. Sonic hedgehog (Shh) is a mitogen for GCPs in vitro, and
Corrales and co-workers now report that positive Shh signalling through the
transcription factor Gli2 is required in vivo to generate enough GCPs for
proper foliation by birth (see p.
5581). The
researchers show that Shh expression correlates spatially and
temporally with foliation, and that in mice lacking Gli2 – the
primary activator of Shh signalling – foliation and GCP number in the
cerebellum at birth are reduced. Shh overexpression in its normal
domain produces normal foliation but increases cerebellar size through
increased GCP proliferation. Given their results, the researchers speculate
that the evolution of the complex cerebellar foliation patterns of higher
mammals may have involved changes in Shh expression patterns.
Related articles in Development:
- Spatial pattern of sonic hedgehog signaling through Gli genes during cerebellum development
- JoMichelle D. Corrales, Gina L. Rocco, Sandra Blaess, Qiuxia Guo, and Alexandra L. Joyner
Development 2004 131: 5581-5590.
[Abstract]
[Full Text]
