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La propulsion par polymérisation d'actine sondée par micromanipulation

Abstract : Dynamic actin networks generate intracellular forces in physiological processes as well as in pathological phenomena like tumor invasion. To detach from the primary tumor and colonize surrounding tissues, neoplastic cells extend a protrusion by actin polymerization then exert a traction force, using actin bundles. The goal of this study is to characterize these actin generated forces by micromanipulation. In the first part of this manuscript, we focus on cell traction using a uniaxial strain experiment on single fibroblasts. The forces exerted by polymerization are studied in the second part. To directly probe the forces generated in the process of actin-based propulsion, we developed a micromanipulation experiment using biomimetic system of Listeria monocytogenes, a model of actin-based motility. By using specially designed flexible handles, a comet growing from a coated polystyrene bead is held between a micropipette and a force probe. This allows us to apply both pulling and pushing external forces up to a few nanonewtons. The elastic modulus of the comet and the adhesion force between the bead and the comet are inferred from fast pulling experiments. The force velocity relation is determined, by applying a constant force on the system, and explained using a dimensional elastic analysis. Finally, varying the pulling speed allows for the characterization of a transition to a regime of dynamic stick-slip instability.
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Contributor : Yann Marcy <>
Submitted on : Thursday, March 25, 2004 - 11:46:31 AM
Last modification on : Monday, December 14, 2020 - 9:55:23 AM
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Yann Marcy. La propulsion par polymérisation d'actine sondée par micromanipulation. Biophysique [physics.bio-ph]. Université Paris Sud - Paris XI, 2003. Français. ⟨tel-00005463⟩

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