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SYED: Symposium Physics of Embryonic Development Across Scales: From DNA to Organisms
SYED 1: Physics of Embryonic Development Across Scales: From DNA to Organisms
SYED 1.2: Hauptvortrag
Montag, 17. März 2025, 10:00–10:30, H1
A tissue rigidity phase transition shapes morphogen gradients — Camilla Autorino1, Diana Khoromskaia2, Bernat Corominas-Murtra3, Zena Hadjivasiliou2, and •Nicoletta Petridou1 — 1EMBL Heidelberg, Germany — 2Francis Crick Institute, UK — 3University of Graz, Austria
Transitions between solid-like and fluid-like tissue material states are essential for morphogenesis. However, if phase transitions instruct cell function is still unknown. Here, we show that tissue rigidification impacts cell signalling by regulating the length-scales and time-scales of morphogen gradients. By combining rigidity percolation theory, reaction-diffusion modelling, quantitative imaging, genetics and optogenetics in zebrafish germ layer formation we uncover that a tissue rigidity phase transition defines the dynamics of fate specification by restricting Nodal morphogen transport and facilitating its signalling dynamics. This is a self-generated mechanism where Nodal, besides triggering cell fate specification, increases cell adhesion via regulating planar cell polarity genes. Once adhesion strength reaches a critical point it triggers a rigidity transition which sharply minimises tissue porosity and induces the formation of tricellular contacts. The resulted tissue reorganisation negatively feeds back to Nodal signalling by sealing the interstitial paths of Nodal diffusion and restricting it close to the source, and by speeding up its degradation. This leads to prompt expression of its inhibitor resulting in robust pattern formation. Overall, we reveal how phase transitions shape morphogen gradients and uncover macroscopic mechanisms of positional information.
Keywords: phase transitions; criticality; morphogen gradients; signalling dynamics