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A Wnt oscillator model for somitogenesis

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We propose a model for the segmentation clock in vertebrate somitogenesis, based on the Wnt signaling pathway. The core of the model is a negative feedback loop centered around the Axin2 protein. Axin2 is activated by beta-catenin, which in turn is degraded by a complex of GSK3beta and Axin2. The model produces oscillatory states of the involved constituents with typical time periods of a few hours (ultradian oscillations). The oscillations are robust to changes in parameter values and are often spiky, where low concentration values of beta-catenin are interrupted by sharp peaks. Necessary for the oscillations is the saturated degradation of Axin2. Somite formation in chick and mouse embryos is controlled by a spatial Wnt gradient which we introduce in the model through a time-dependent decrease in Wnt3a ligand level. We find that the oscillations disappear as the ligand concentration decreases, in agreement with observations on embryos.
OriginalsprogEngelsk
TidsskriftBiophysical Journal
Vol/bind98
Udgave nummer6
Sider (fra-til)943-950
Antal sider8
ISSN0006-3495
DOI
StatusUdgivet - 17 mar. 2010

ID: 32671790