Hugo Wioland

My long term scientific project aims at understanding how diverse actin filament networks can emerge and coexist within a single cell. I am particularly interested in the many factors that make each actin filament unique, despite being assembled from the same pool of nearly identical actin monomers:

• Mechanical regulation: I have implemented a number of experimental setups to apply tension, torsion and curvature to single actin filaments, and shown for example that the actin binding protein ADF/cofilin exerts a torsion that boost filament fragmentation. I am now pursuing how individual and combined mechanical constraints can regulate protein binding to filaments.
• Actin post-translational modification: despite the fact that actin monomers can harbors a myriad of PTMs, their impact on actin dynamics has been barely studied. I have extensively studied actin Met44 and Met47 oxidation by the oxidoreductase MICAL1 and now aim at identifying and characterising other modifications.
• Tropomyosins: by covering >80% of filaments in cells, tropomyosins regulate the activity of many other actin binding proteins and thus defines the filaments’ identity. I am particularly interested in the factors that determine which tropomyosin isoform will cover actin.

To better explore actin filament biochemical and biomechanical properties, we perform in vitro experiments with purified and fluorescently labelled proteins. Hundreds of single actin filaments are typically reconstituted inside a microfluidic chamber and exposed to solutions containing the proteins of interest. This allows us to precisely quantify actin filaments and their binding partners dynamics, and characterise the molecular interactions which shape filament networks inside cells.