Building and disassembling actin filaments with proteins and forces
Antoine Jégou (Institut Jacques Monod, France)
The actin cytoskeleton comprises several networks essential for the cell to perform many key functions (motility, cell division, tissue cohesion, …). Their assembly and disassembly is tightly regulated, in space and time, by a myriad of actin binding proteins but also by the mechanical stress applied to those networks. We take advantage of a simple setup based on microfluidics and fluorescence microscopy, to manipulate actin filaments in vitro and assay the regulation of actin assembly. Focusing first on the assembly of filaments by formins, which are able to track filament barbed ends and accelerate their elongation from profilin-actin, we will show how tracking and rapid elongation are modulated by filament tension and regulatory proteins. We will then focus on ADF/cofilin isoforms, which play a central in filament disassembly. We will show how ADF/cofilin fragments and depolymerizes filaments through different mechanisms, targeting both the side and the ends of the filaments.