Coupling biological pattern formation and size control via mechanical forces
Institute for Molecular Systems Biology, ETH Zurich
Department of Physics, University of Konstanz
Institute for Molecular Biology, University of Zurich
Institute for Molecular Systems Biology, ETH-Zurich
Last modified: March 30, 2006
For morphogenesis it is critical that pattern formation and size control are tightly coupled. Such coupling could be realized if both pattern formation and growth are regulated by the same factors. Generally, local differences in signaling activity are required for pattern formation. However, if growth would depend on these same activity levels, this could pose too severe geometric restrictions on the morphogenesis of certain tissues. Here, we address this issue for the wing imaginal disc of Drosophila, which is commonly used as a model system to study patterning and growth in developmental biology. There, patterning and growth are indeed regulated, at least in part, by the same factors. One of them is Decapentaplegic (Dpp), which is a key regulator of both processes. However, even though Dpp forms a gradient, growth occurs in a uniform fashion. We have developed a model, in which growth is not only regulated by gradient forming growth factors like Dpp, but also by mechanical forces. These forces are generated as a result of local growth induced by the growth factors. In particular, stretching induces growth and compression inhibits it. Using numerical simulations, we show that the model yields the observed uniform growth and that it can account for the termination of growth without the requirement of any external factors. Furthermore, the model can explain available experimental results in which the wing disc has been manipulated genetically.