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Séminaire « Matière molle : organisation et dynamique » de l’INSP

Some physical aspects of single-cell mechanosensing - Atef Asnacios - Vendredi 24 juin 2016 à 11 h

INSP - 4 place Jussieu - 75252 PARIS Cedex 05 - Barre 22-32 - 2e étage, salle 201

Atef Asnacios, Laboratoire Matière et Systèmes Complexes, Université Paris Diderot-CNRS

Abstract

As part of their physiological functions, most cells need to adapt to their mechanical environment. In particular, the rigidity of the extracellular matrix was shown to control cell traction forces, shape, and ultimately cell differentiation. In this context, most studies focused on the role of biochemical regulation in rigidity sensing. In contrast to this biochemical signaling-centered approach, our aim is to reveal the physical/mechanical phenomena involved in mechanosensing. To this end, we developed a single-cell technique allowing us to measure the traction force and speed of shortening of individual cells deflecting microplates (i.e. springs) of variable stiffness. We will show that the mechanical power invested by the cell to bend the microplates is adapted to stiffness, and reflects the response of myosin-motors to load. We will also present a unique protocol allowing us to change the effective stiffness felt by a single cell in real time ( 0.1 second). This technique revealed that cell contractility was instantaneously adapted to a sudden change in stiffness, indicating that an early purely mechanical response to stiffness indeed does exist. Finally, we will present the results of experiments combining single-cell traction force measurements, dynamic control of stiffness, and monitoring of adhesion complexes, and will discuss how cell shape and mechanical adaptation to rigidity could control cell fate.