Physical influences of the extracellular microenvironment on cell migration
Associate Pr. Sylvain Gabriele
University of Mons, Mechanobiology & Soft Matter group
Interfaces and Complex Fluids Laboratory,
B-7000, Mons, Belgium
Cell migration is a fundamental process for embryonic development, wound healing, immune responses and for pathological processes such as cancer metastasis. This process is highly regulated by biophysical interactions between migrating cells and the extracellular matrix (ECM). How the physical aspects of the cell's environment affect cell migration poses a considerable challenge when trying to understand migration in complex tissue environments. To address this issue, we studied the migration of highly motile fish keratocytes by imposing modifications of the matrix stiffness and two-dimensional confinement conditions.
We show that polarization and persistence of motile keratocytes are regulated by the matrix stiffness over seven orders of magnitude, without changing the cell spreading area. In addition, matrix stiffness can be considered as a valuable tool for modulating the natural phenotypic variability of motile keratocytes. Our findings demonstrate that matrix stiffness mediates cell polarization through the distribution of myosin II that drives the actin meshwork at the leading edge and the formation of actin stress fibers at the rear side. Keratocytes remain rounded and form nascent adhesions on compliant substrates, whereas large and uniformly distributed focal adhesions are formed on fan-shaped keratocytes migrating on rigid surfaces. Mechanistically, we determine that the molecular clutch requires the engagement of α5β1 integrins for rigidity sensing, whereas αVβ3 integrins only do not permit polarization and persistence.Then, we used microcontact printing to produce a two-dimensional confinement by imposing specific boundary conditions. The confinement of fish keratocytes on fibronectin-coated lines to a symmetric breaking of polarized cells. We show that morphological and migrating parameters are dependent on the level of confinement, demonstrating that cell confinement dictates the migrating speed and the level of polarization of motile cells. We used original mechanical forces assays to measure the lamellipodial protusive force (atomic force microscope cantilever) and the contractile forces (traction force microscopy) as a function of the level of confinement. By combining confocal and super-resolution microscopy with time-lapse assays, we demonstrate that confined fish keratocytes undergo drastic morphological modifications, which are driven by large modifications of actin and microtubules networks.
The Mechanobiology & Soft Matter group belongs to the Interface and Complex Fluids Laboratory at the University of Mons. We seek to understand the basic physical principles underlying force transmission and elucidating how cell mechanical properties regulate cellular functions. Our experimental approach of cell mechanics takes advantage of physical chemistry of soft condensed matter and engineering sciences to address physiological questions at single-cell and tissue levels.
Date of update October 2, 2016