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Forces, shape and structure of living cells

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Living cells come in a wealth of different shapes depending on their
esurroundings. The organisation of their polymeric skeleton reflects
this diversity. Using rheology approaches, we seek to analyse the
cell’s mechanical balance.

Living cells possess a cytoskeleton made of polymer chains, which they continuously re-shape, and which are bound together (crosslinked) by transient molecular bonds, lasting for seconds only. Also, other molecular bonds are indeed molecular motors, able to exert contractile (pulling) forces within the cytoskeleton. These forces are transmitted onto the cell’s environment, allowing it to deform its substrate, and, through a yet unclear mechanism, to move.

Using optical microscopy techniques (including fluorescence of key-molecules involved in these mechanisms) jointly with traction force measurements on single cells (microplate device), we have been able to characterise the mechanical behaviour of the cytoskeleton (Mitrossilis et al., 2009 and 2010) and demonstrate that a rheological model (Etienne et al, 2015) can predict the complex behaviours of cell force modulation in response to the surroundings’ stiffness.

However, for the time being our model does not include the mechanisms of force transmission to the substrate via cell adhesion. The aim of this internship is to explore the possibilities of modelling the contribution of adhesion, using experimental results allowing visualisation of the adhesion zones geometry simultaneously with force measurement (Fouchard et al, 2014).

Contact :

Jocelyn Etienne <jocelyn.etienne@ujf-grenoble.fr>

Atef Asnacios <atef.asnacios@univ-paris-diderot.fr>