The influence of vimentin on actin dynamics and force generation in RPE1 cells

Abstract

The cytoskeleton is a network of filaments in cells, it consists of actin filaments, intermediate filaments and microtubules. It is very dynamic and plays a key role in many biological processes such as cell migration and cell division. Actin stress fibers are involved in force generation, cell retraction and cell protrusion during migration. The polymerization and depolymerization of actin filaments regulate cell migration and are influenced by the activity of actin binding proteins. Even though no motor molecules bind to vimentin, and it does not generate forces, its role is important in the regulation of cell migration. To better understand the mechanism of cell migration, it is important to understand how cytoskeleton filaments interplay. Therefore, understanding the role of vimentin on actin dynamics, and its implication in actin force generation are the two main interests of my Ph.D. thesis. I first measure actin dynamics in vimentin depleted cells using fluorescence recovery after photobleaching. I show that silencing of vimentin expression slows down actin dynamics but does not affect the fraction of actin monomers that participate. In addition, I show that plectin as a vimentin-actin cross-linker protein does not have the same effect. Finally, I study actin force generation using traction force microscopy. I show that silencing of vimentin disarranges the distribution of traction forces and adhesion sites but does not impact the magnitude of traction forces.