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Accueil > Équipes > Mécanique des Cellules en milieu Complexe

Subcellular Structures and Single Cells

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Claude Verdier, Valérie Laurent, Pierre Recho, Jocelyn Etienne, Karin John

Cell Migration and Cell Volume Regulation

Cell dynamics over various timescales play a key role in both healthy and pathological processes such as wound healing or metastatis. Such problems involve the interplay of biological (via genes expression), chemical (via interaction pathways between molecules) and mechanical (via forces and deformations) factors which need to be integrated in an appropriate model to capture specific phenomenons such as cell motility or cell volume control in response to various environmental perturbations (external forces, external rheology, diffusible molecules in the solution etc...). This leads to novel continuum medium theories of active matter which consume energy and store information at each material point of the system. In the team, we also have the goal to understand how the dynamics of individual cells can conspire to collectively self-organize into biological tissues. Read more here or here.

Contact : Pierre Recho

Mechanics and Dynamics of Subcellular Structures

Microtubules are a central structure in living cells, involved in cell division, migration, and intracellular transport. Therefore, they are a primary drug target against severe pathologies, among them neurodegenerative diseases and cancer. A complete understanding of the mechanisms regulating their dynamics and stability is a central issue in cell biology and a key challenge for human health.

Microtubule lattice dynamics at protofilament dislocations.
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Common textbook knowledge states that the microtubule lattice dynamics is restricted to elongation and shortening at the microtubule tips. The irreversible hydrolysis of GTP-tubulin at the microtubule tip gives rise to a non-equilibrium phenomenon, called “dynamic instability”. This behavior is crucial for many cellular processes, e.g. spindle positioning during mitosis, where microtubules switch rapidly between elongation and shortening phases. Since the discovery of the dynamic instability more than 30 years ago, research on microtubule regulation has been mainly focused on mechanisms acting on the microtubule tip.

Recently, we discovered that the microtubule shaft lattice shows an unexpected dynamics. Tubulin dimers incorporate directly into the shaft lattice in localized regions. Our experimental data and model simulations suggest, that structural defects might be the origin of the observed localized tubulin incorporation. Read more here.

Contact : Karin John
Experimental collaborators : Laurent Blanchoin & Manuel Théry (Cytomorpholab), Denis Chrétien (IGDR Rennes)

Residual Stresses, Morphological and Mechanical Instabilities, Mechano-Chemical Coupling

Growth is a key feature of living matter. Often, growth is associated with the generation of elastic strains and stresses, which couple back to the growth process and may lead to morphological instabilities. In order to model the growth dynamics of elastic bodies with such residual stresses a thermodynamically consistent approach is needed for the correct description of the cross-coupling between growth and mechanics.

Stress buildup in an elastic fibre network through interfacial growth.

As an example, we have applied a variational principle to the formulation of the interfacial growth dynamics of dendritic actin filament networks growing from biomimetic beads, an experimentally well studied system, where the buildup of residual stresses governs the network growth. The arising morphological instabilities due to mechano-chemical coupling mechanisms and the presence of mechancial pre-stresses play a major role in locally organizing the cytoskeleton of living cells. Read more here.

Contact : Jocelyn Etienne, Pierre Recho, Karin John