The mechanics of symmetry breaking in cell migration

Orateur : Soutenance de Thèse de Katarina HENNIG

Résumé : Symmetry breaking in biology is at the origin of the appearance of functional shapes in multicellular assemblies. This process relies on the ability of single cells to perform directed migration and relatedly to establish a front-rear polarity. The initiation of cell migration, in absence of external cues, has been attributed to the capacity of the cytoskeleton to spontaneously polarize. However, how the linked generated forces evolve due to changes of the mechanical interaction of the cell with the substrate remains to be determined. We here report a uni-dimensional migration assay, mimicking in vivo fibrillar environment, compatible with high resolution force imaging. Synchronized measurements of both morphometric and mechanical parameters revealed a generic stick-slip behavior initiated by stochastic adhesion detachment on one side of the cell. Unexpectedly, this process can occur in absence of any pre-established polarity. A theoretical model is proposed that accurately describes this behavior. The relevance of stochastic stick-slip process is confirmed by the analysis of several cell types.

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