6th Annual Symposium
Physics of Cancer
Leipzig, Germany
September 7-9, 2015
Invited Talk
Signals and mechanics guiding cellular organization in epithelia
Daiki Umetsu1, Katrin Rudolf1, Benoît Aigouy2, Maryam Aliee3, Suzanne Eaton2, Frank Jülicher3, Christian Dahmann1
1Technische Universität Dresden, Institute of Genetics, 01062 Dresden, Germany
2Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
3Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01187 Dresden, Germany
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Many epithelial tissues are organized into subpopulations of cells with distinct functions or fates. Maintaining straight boundaries between these different cell populations within tissues requires mechanisms to counteract cell rearrangements and cell mixing caused by cell division and tissue reshaping. Local increases in mechanical tension are important in segregating cell populations at boundaries within tissues, yet the signals that control increases in mechanical tension and the mechanisms by which mechanical tension influences cellular dynamics to segregate cell populations remain unknown. Here we demonstrate that the Hedgehog signaling pathway is necessary and sufficient to increase mechanical tension along the boundary between anterior and posterior cell populations in Drosophila wing imaginal discs. Moreover, by quantitatively analyzing cellular dynamics in the vicinity of tissue boundaries in pupal Drosophila histoblasts, we show that cell mixing within the same cell population involves multiple cell intercalations. Cells also intercalate along boundaries between different cell populations, junctional rearrangements during intercalation, however, are biased to disfavor cell mixing. Simulations of tissue growth with two cell populations suggest that local increases in mechanical tension can account for the observed bias in junctional rearrangements during intercalation. We propose that Hedgehog signaling induces local increases in mechanical tension and that mechanical tension guides cell segregation at tissue boundaries by biasing cell intercalations.
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