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Building Distinct Actin Filament Networks in a Common Cytoplasm

Project description

Investigating the mechanisms of actin binding proteins

Actin is a major protein component of the cytoskeleton that exists in monomeric and polymeric or filament forms. Actin filaments play a vital role in cellular functions such as motility, endocytosis, cell division and muscle contraction. Actin binding proteins (ABPs) determine the structure, organisation and dynamics of the actin filaments. However, details of the mechanisms through which they function in their environment remain obscure. The ERC-funded SegregActin project aims to discern how cells induce the formation of actin networks of favourable ABP composition from an inventory of cytoplasmic constituents. It also seeks to determine the relationship between the ABP composition of actin networks, and their geometrical, dynamical, and rheological properties.


"The ability of cells to use the actin cytoskeleton for a diversity of cellular processes is due to the fact that actin filaments, although assembled from identical subunits, are organized in a wide variety of structures of appropriate geometrical, dynamical and rheological properties. Key players in this regulation are specific sets of actin binding proteins (ABPs) interacting with each actin networks, to modulate spatially and temporally their properties.
With this project, I want to understand 1/ how cells can generate the formation of actin structures of appropriate ABP composition from a common pool of cytoplasmic components and 2/ the relationship between the ABP composition of an actin network, its geometrical and dynamical properties, and its response to mechanical deformations.

I will hypothesize that the generation of an actin network of appropriate ABP composition can be explained with an original model, taking into account the facts that 1/ actin filaments in cells are not all structurally identical, but adopt specific conformations that are favored and stabilized by certain families of ABPs; and 2/ the interaction of ABPs with actin depends of the geometrical organization of the filaments.

Because this project imposes to study protein-protein interactions in the presence of multiple partners, I propose to develop an unprecedented strategy combining 1/ ""bottom-up"" reconstitutions, where limited sets of ABPs are added one-by-one in the system to understand their combined activities with actin; and 2/ ""top-down"" reconstitutions with protein extracts prepared from a genetically-tractable organism (the yeast S. cerevisiae), where proteins can be removed one-by-one, in order to study actin network properties in near-physiological conditions.

This project will shed a new light on how cells organize their interior, and will represent a unique opportunity to understand how modifications in the expression of ABPs are associated with actin network defects.

Host institution

Net EU contribution
€ 1 500 000,00
75794 Paris

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Ile-de-France Ile-de-France Paris
Activity type
Research Organisations
Total cost
€ 1 500 000,00

Beneficiaries (3)