Periodic Reporting for period 4 - Self-Control (Interplay between genetic control and self-organization during embryo morphogenesis)
Berichtszeitraum: 2023-05-01 bis 2024-10-31
This project addresses the fundamental property of living matter to be organized. Tissues that loose the capacity to control their form are functionally perturbed, as in cancers and many other diseases. Biological organisation is a keystone feature of all living matter accross scales from molecular assemblies, cells, to organisms. Understanding what underlies this is a major challenge that requires expertise from different disciplines.
We study here the form of biological tissues and what underlies acquisition of specific forms. We are interested in how mechanical forces and chemical signals exchanged by cells orchestrate the dynamics of cells and thereby tissue shape changes, a process called morphogenesis. In the context of this research project we study two kinds of tissue dynamics: tissue flow and a wave of tissue deformation. Like in a fluid, activity and deformation can be transported (flow) or propagated (wave) in a tissue.
We address the nature of the mechanical and chemical activities that orchestrate the flow and wave dynamics occurring in embryonic tissues.
We study here the form of biological tissues and what underlies acquisition of specific forms. We are interested in how mechanical forces and chemical signals exchanged by cells orchestrate the dynamics of cells and thereby tissue shape changes, a process called morphogenesis. In the context of this research project we study two kinds of tissue dynamics: tissue flow and a wave of tissue deformation. Like in a fluid, activity and deformation can be transported (flow) or propagated (wave) in a tissue.
We address the nature of the mechanical and chemical activities that orchestrate the flow and wave dynamics occurring in embryonic tissues.
We made the following discoveries throughout this project.
First, we characterized the mechanisms underlying the emergence of directional tissue flow associated with embryonic axis extension during Drosophila gastrulation. We showed that tissue flow requires the interaction between the spatial pattern of cell contractility and the pattern of tissue curvature. We also characterized the mechanisms underlying the asymmetric pattern of cell contractility along the dorsal-ventral axis of the embryo. This illustrates the interplay between genetic patterning, mechanics and embryo geometry in guiding tissue morphogenesis.
Second, we unravelled the mechanisms of self-organised tissue morphogenesis. We reported the existence of a mechanochemical feedback between the embryonic tissue and the surrounding vitelline membrane of the embryo. In particular, we showed that adhesion and deadhesion to the egg shell is required for the wave propagation. Additionally, we discovered that the wave requires a multicellular pattern of contractility that depends on secretion and diffusion of a « mechanogen » that forms an activity gradient at the cell surface accross the tissue.
First, we characterized the mechanisms underlying the emergence of directional tissue flow associated with embryonic axis extension during Drosophila gastrulation. We showed that tissue flow requires the interaction between the spatial pattern of cell contractility and the pattern of tissue curvature. We also characterized the mechanisms underlying the asymmetric pattern of cell contractility along the dorsal-ventral axis of the embryo. This illustrates the interplay between genetic patterning, mechanics and embryo geometry in guiding tissue morphogenesis.
Second, we unravelled the mechanisms of self-organised tissue morphogenesis. We reported the existence of a mechanochemical feedback between the embryonic tissue and the surrounding vitelline membrane of the embryo. In particular, we showed that adhesion and deadhesion to the egg shell is required for the wave propagation. Additionally, we discovered that the wave requires a multicellular pattern of contractility that depends on secretion and diffusion of a « mechanogen » that forms an activity gradient at the cell surface accross the tissue.
Our project is intrinsically interdisciplinary, and rests on collaborations between biologists and physicists, both expeirmental and theoretical.
Our project revealed two main unexpected features of tissue morphogenesis in vivo. First, we revealed the role of the vitelline membrane, the mechanical envelope of the embryo, as a geometric template for tissue flow based on the imposed tissue curvature pattern, and as a mechanical substrate for the wave of propagation. In addition, the vitelline membrane forms a chemical environment for diffusion and organisation of a long range « mechanical morphogen ». Thus, our work emphasized the role of the mechanical environment surrounding the embryonic tissues during embryo morphogenesis.
Second, we revealed the interplay between guided and self-organised dynamics during embryo morphogenesis. This led us to consider in new ways information flow during development, and in particular the role of geometry as a key module of information per se, together with chemical and mechanical information.
Our project revealed two main unexpected features of tissue morphogenesis in vivo. First, we revealed the role of the vitelline membrane, the mechanical envelope of the embryo, as a geometric template for tissue flow based on the imposed tissue curvature pattern, and as a mechanical substrate for the wave of propagation. In addition, the vitelline membrane forms a chemical environment for diffusion and organisation of a long range « mechanical morphogen ». Thus, our work emphasized the role of the mechanical environment surrounding the embryonic tissues during embryo morphogenesis.
Second, we revealed the interplay between guided and self-organised dynamics during embryo morphogenesis. This led us to consider in new ways information flow during development, and in particular the role of geometry as a key module of information per se, together with chemical and mechanical information.