Interrogation optogénétique du concept d’homéostasie de tension à l’échelle cellulaire

Orateur : Soutenance de Thèse de Tomas ANDERSEN

Résumé : The structural stability and mechanical integrity are key elements for the proper functioning and preservation of complex living systems. Being in constant interaction with their surroundings and subjected to external inputs, such systems need to be able to face changes in order to thrive. These inputs can affect the system both in a localized way or disturb it as a whole. Any perturbations that cannot be mechanically withstand by the living system will result in a crucial malfunctioning or, ultimately, in its death. The general mechanism responsible for maintaining the system’s physiological conditions at the proper state, despite environmental variations, is identified as homeostasis. More specifically, one of the processes known in mechanobiology to preserve the appropriate mechanical equilibrium of a living system is called tensional homeostasis. It is important to note that all of the above stated holds true both at the scale of collective behaviour of complex organisms, and all the way down to the single cell level. In fact, it is actually this last small scale which draws our interest. Cells face constant mechanical perturbations from their surrounding and are able to respond accordingly maintaining a relatively stable internal mechanical state. The existence of this internal tensional equilibrium relies on a very dynamic process with constant feedback loops between the internal biochemical contractile machinery and the external active generated forces. Our interest is to understand better this active mechanism by dynamically perturbing the tensional homeostatic system while studying its return to equilibrium.

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