First published online April 25, 2008
Development 135, 104e (2008)
© The Company of Biologists Limited
Notch and Sox: different routes to progenitor maintenance
During development of the chick nervous system, a combination of Notch
signalling and SoxB1 transcription factors (Sox1, Sox2 and Sox3) maintains a
pool of self-renewing stem and progenitor cells. On
p. 1843, Jonas Muhr
and colleagues investigate whether Notch and SoxB1 proteins suppress neuronal
differentiation through the same, or different, pathways. By expressing
dominant-negative components of these pathways in chick embryos, they show
that, although Notch requires SoxB1 to maintain progenitor characteristics,
SoxB1 activity blocks neurogenesis independently of Notch. Notch represses the
activity of bHLH proneural proteins via the bHLH transcription factors Hes1
and Hes5, but, the researchers found, also represses E-proteins - the
heterodimerizing partners of proneural proteins - through a Hes-independent
mechanism. SoxB1 proteins, by contrast, seem to maintain progenitors by
creating a molecular environment in which E-proteins and proneural proteins
cannot promote neuronal differentiation. As Notch, Sox and bHLH proteins are
also expressed in muscle and neural crest progenitor populations, the authors
suggest their results could be of broader relevance.

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Related articles in Development:
- SoxB1 transcription factors and Notch signaling use distinct mechanisms to regulate proneural gene function and neural progenitor differentiation
- Johan Holmberg, Emil Hansson, Michal Malewicz, Magnus Sandberg, Thomas Perlmann, Urban Lendahl, and Jonas Muhr
Development 2008 135: 1843-1851.
[Abstract]
[Full Text]