Séminaire de l’Institut Jacques Monod – Laurent Blanchoin & Manuel Théry

Invité par l’équipe Romet-Lemonne/Jégou, Manuel Théry (Directeur de Recherche CEA, Cytomorpholab, ESPCI/IPGG, Paris) et Laurent Blanchoin (Directeur de Recherche CNRS, Cytomorpholab, IRIG/LPCV, Grenoble) présenteront un séminaire de l’Institut Jacques Monod sur le thème :

The self-renewing cell: how actin networks are built, sized, and dismantled

Résumé :

The actin cytoskeleton continuously assembles and disassembles its filaments, a process of self-renewal essential for cell shape, movement, and response to the environment. Yet how the cell coordinates this renewal across multiple coexisting actin structures, and what sets the rate at which individual networks turn over, remains poorly understood. Using a minimal reconstituted system with either unlimited or limited monomer availability, we show that when monomers are scarce, competition between distinct actin architectures profoundly disrupts turnover: as competition increases, the turnover rate of individual networks decreases. Actin turnover is therefore not an intrinsic property of individual networks but an emergent outcome dictated by the competitive balance between coexisting architectures. We then show that this principle operates in living cells: when cells increase their spreading area, the expanding cytoskeleton monopolizes available monomers, forcing a slowing of turnover at the whole-cell scale. Together, these results establish competition between actin structures as a fundamental determinant of turnover, revealing how the global cytoskeletal state collectively shapes the dynamic properties of each individual network