From: INSTITUTE CURIE, Paris

Will give a seminar entitled:

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 and 

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^3,4.

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 mice⁵. With pathological amplification to tumorigenic levels in neighbouring healthy cells compressed by tumour growth pressure, in vivo by using magnetic^5,6 and ultrasonic tools.

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