First published online December 7, 2007
Development 135, 104e (2008)
© The Company of Biologists Limited
Segmentation clock: Wnt3a out of time?
According to the `clock and wavefront' model of somitogenesis, a
segmentation clock driven by oscillations of Notch, Fgf and Wnt signalling in
the presomitic mesoderm (PSM) is translated into a periodic array of somites
at the so-called wavefront. Wnt3a/β-catenin signalling is widely believed
to be a component of this clock, but on
p. 85, Terry Yamaguchi
and colleagues surprisingly suggest otherwise. To study Wnt3a's role in somite
segmentation, the researchers introduced conditional loss- and
gain-of-function β-catenin alleles into mice. Their findings show that
although Wnt3a is necessary for the clock gene oscillations that occur during
somitogenesis, Wnt3a/β-catenin signalling does not function as an
integral component of the segmentation clock because small, irregular and
abnormally located somites do develop in the absence of β-catenin and
cycling clock gene expression. From their results, the researchers conclude
that Wnt3a/β-catenin signalling has a permissive, rather than an
instructive, role in the oscillation of clock genes, and that it controls
somite boundary formation by regulating the anteroposterior position of
segment boundary-determining genes.
Related articles in Development:
- Wnt3a/β-catenin signaling controls posterior body development by coordinating mesoderm formation and segmentation
- William C. Dunty, Jr, Kristin K. Biris, Ravindra B. Chalamalasetty, Makoto M. Taketo, Mark Lewandoski, and Terry P. Yamaguchi
Development 2008 135: 85-94.
[Abstract]
[Full Text]
