Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - SegregActin (Building Distinct Actin Filament Networks in a Common Cytoplasm)

Teaser

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...

Summary

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.
The objective of this project is 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.

Work performed

During this first period of the project, the principal investigator started to work with an engineer (recruited independently by the University of Aix-Marseille) and 2 graduate students. The recruitment of 2 post-docs is planned for the beginning of the second reporting period. Since the lab was starting its activity in Marseille, the first months were dedicated to the installation of the new team and the purchase of all equipment.

Tasks planned for the first year of the project were all started. We purified and fluorescently labeled most of the proteins that are needed for the project. We started actin assembly experiments in vitro to find conditions in which 2 different types of actin networks can be assembled within a same sample.
In parallel, we generated a number of yeast mutant strains and prepared cellular extracts. We have adapted the use of paramagnetic microbeads force sensors to our protein and extract system. We have been able to probe the mechanical properties of actin networks assembled both from yeast cytoplasmic extract or from minimal sets of purified proteins.

Final results

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.