Christian Dahmann Group
Signals and mechanics in epithelial morphogenesis
© Kirsten Lassig
The general interest of our group is to understand the mechanisms by which cells collectively organize to form complex patterns and morphologies in developing tissues. How do mechanical processes like cell adhesion and force generation influence tissue organization? And how are these mechanical processes linked to the chemical signals that orchestrate tissue development? We address these questions by combining genetics with live imaging, quantitative image analysis and biophysical approaches using the fruit fly Drosophila melanogaster as a model organism. In addition, in collaboration with physicists and mathematicians, we develop mechanical models of epithelial morphogenesis.
The sorting out of cells with different identities and fates during animal development is an important process to organize functional tissues and organs. We have previously shown that the sorting of cells at the boundary between anterior and posterior compartments of the developing Drosophila wing is controlled by a transcriptional response to the Hedgehog signaling molecule. Recent physical approaches, including the ablation of bonds between cells using laser light, have revealed that mechanical tension on cell bonds is elevated along this anterior-posterior compartment boundary. Computer simulations, performed in collaboration with the group of Frank Jülicher at the MPI-PKS, show that a local increase of cell bond tension suffices to maintain straight interfaces between compartments. Our results suggest a sorting mechanism by which an increased cell bond tension guides the rearrangement of cells after cell division to maintain straight and sharp compartment boundaries.
Epithelial tissues undergo profound changes in shape during animal development. We have recently shown that signaling by BMP, once thought to maintain cell survival, helps to control epithelial cell shape and organization in the developing Drosophila wing. We are currently investigating how the BMP signaling pathway influences the mechanical properties of cells to guide changes in cell and tissue shape.
Future Projects and Goals
- Identifying the molecular pathway leading from the Hedgehog signal to increased mechanical tension
- Investigating the dynamics of cell sorting at compartment boundaries by real-time in vivo imaging
- Analyzing tissue-scale mechanical properties of the wing epithelium during development
- Reconstructing the developing wing epithelium at cellular resolution in three dimensions
Methodological and Technical Expertise
- Drosophila genetics
- Live imaging
- Laser ablation
- Quantitative image analysis