Oriented flows can organize multi-cellular systems

Date

Jan 30, 2025

Time

11:00 AM - 12:00 PM

Speaker

Matthias Merkel

Affiliation

Alan Turing Center for Living Systems, Aix-Marseille Université

Series

MPI-CBG Thursday Seminar

Language

en

Main Topic

Biologie

Host

Pierre Haas

Description

Most animals display one or more body axes (e.g. head-to-tail, dorsal-ventral, left-right). In our work, we demonstrate that the formation of the primary, head-to-tail, axis can be promoted by large-scale tissue flows. Specifically, we study aggregates of mouse embryonic stem cells, called gastruloids, which are initially spherically symmetric, but later form an axis defined by the polarized expression of the transcription factor T/Brachyury. We show that advection of cells with tissue flows contribute substantially to the overall polarization, and that these flows are driven by effective interface and surface tension differences. We further discuss flows in the context of convergent extension (CE). From a physics perspective, tissues undergoing CE can be described as oriented active materials. However, such materials are inherently unstable, raising the question of how CE during development can be robust. We show that the presence of a signaling gradient can stabilize the process, but only if it acts to actively extend the tissue along the gradient direction. Conversely, tissues are unstable if they tend to actively contract along the gradient direction. Intriguingly, developing tissues seem to exclusively use the gradient-extensile and not the unstable gradient-contractile coupling. This suggests that the active matter instability acts as an evolutionary selection criterion. In other words, our work points to a new principle of multi-cellular development that is directly rooted in active matter physics.

Last modified: Jan 30, 2025, 7:35:10 AM