As part of the MECABIONIC program, Prof. Emmanuel Farge (Institute Curie) and Prof. Daniel Riveline (IGBMC, Strasbourg) will give a class on mechanobiology.
The fundamental classes are open to the public without registration!

 

From mechanotransduction behavioural evolutionary origins of first metazoans to tumorigenic mechanical induction

The evolutionary emergence of the primitive gut in metazoans, one of the decisive events that conditioned the major evolutionary transition leading to the origin of animals, is thought to have been intimately associated with the formation of multicellular invagination (i.e. gastrulation) and its differentiation as an endomesoderm.
However, the biochemical signals at the origin of gastrulation and its endomesoderm specification remain uncertain. Indeed, we will see that the different biochemical pathways involved in modern animals early embryos endomesoderm formation are not widely conserved across suerphyla. Interestingly, activation of Myo-II, and of the b-cat pathway by phosphorylation of Y654-bcat, has been shown to be triggered by mechanotransduction to lead to mesoderm invagination in Drosophila embryos and endomesoderm specification during gastrulation and epiboly in Drosophila.
We will describe how hydrodynamic mechanical stresses, reminiscent of soft marine flow, trigger gastrulation and tissue inversion via a myosin-dependent mechanotransductive process in the metazoan Nematostella vectensis (Cnidaria) and the multicellular choanoflagellate Choanoeca flexa, considered to be the closest living relative of the metazoans. We also describe that, as in bilaterian animals, gastrulation in the cnidarian Nematostella vectensis induces biochemical specification of the endomesoderm through mechanical activation of the b-catenin pathway via phosphorylation of Y654.
We will see that these observations suggest that the primitive emergence of the intestine in Metazoa may have been initiated by marine mechanical constraints in multicellular pre-Metazoa more than 700 million years ago, thanks to the mechanosensitive properties of Myosin, which were crucial for this evolutionary transition. A process carried out by the specification of the endomesoderm via mechanosensitive proteins containing Y654-b-catenin enabled evolutionary emergence in the first Metazoa and is specifically conserved in all Metazoa (1,2).
As part of a putatively inherited reminiscent process, it was found that spontaneous myogenic gastric pulses mechanotransductively inducing physiological levels of b-catenin-dependent stem cells in the colon of now-adult mice (3). With pathological amplification to tumorigenic levels in neighbouring healthy cells compressed by tumour growth pressure, in vivo by using magnetic (3,4) and ultrasonic tools.
1 Nguyen, N. M. et al. bioRxiv 2020.12.03.407668 (2020).
2 Nguyen, N. M. et al. Front Cell Dev Biol 10, 992371 (2022).
3 Nguyen Ho-Bouldoires, T. H. et al. Commun Biol 5, 137 (2022).
4 Fernandez-Sanchez, M. E. et al. Nature 523, 92-95 (2015).

 

Symmetry breaking and collective effects in biological physics

Biological cells move, divide, change their shapes, adhere to their neighbors and environments to form tissues and organs. These phenomena are essential for a wide variety of biological processes during morphogenesis for example but their mesoscopic origins are often yet not clarified. To characterize them, out-of-equilibrium dynamics can be studied with physical experimental designs and associated theories. These topics have triggered new physical formalisms which call for original experimental calibrations and tests associating tightly quantitative biology with the design of new setups and models for living matter. I will illustrate these experiments of biological physics with the following examples : spontaneous breaking of symmetry for single cell motion, collective effects in elongation of epithelial colonies, spontaneous rotations in 2D and in 3D. These phenomena will show that basic principles in physics can be used and challenged to unravel new cellular mechanisms with physiological relevance.

Link:
https://mecabionicschool.sciencesconf.org/resource/page/id/3