title: Force fluctuations in three-dimensional suspended fibroblasts.
abstract: Cells are sensitive to mechanical cues from their environment and at the same time generate and transmit forces to their surroundings. To test quantitatively forces generated by cells not attached to a substrate, we used a dual optical trap to suspend 3T3 fibroblasts between two fibronectin-coated beads. In this simple geometry, we measured both the cells' elastic properties and the force fluctuations they generate with high bandwidth. Cell stiffness decreased substantially with both myosin inhibition by blebbistatin and serum-starvation, but not with microtubule depolymerization by nocodazole. We show that cortical forces generated by non-muscle myosin II deform the cell from its rounded shape in the frequency regime from 0.1 to 10 Hz. The amplitudes of these forces were strongly reduced by blebbistatin and serum starvation, but were unaffected by depolymerization of microtubules. Force fluctuations show a spectrum that is characteristic for an elastic network activated by random sustained stresses with abrupt transitions.
authors.affiliation: Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Schlosser
authors.affiliation: Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany rehfeldt@physik3.gwdg.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Rehfeldt
authors.affiliation: Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany cfs@physik3.gwdg.de.
authors.forename: Christoph F
authors.initials: CF
authors.lastname: Schmidt
mesh_terms: D016475:3T3 Cells; D000199:Actins / Q000502:physiology; D000818:Animals; D001696:Biomechanical Phenomena; D002448:Cell Adhesion / Q000502:physiology*; D005347:Fibroblasts / Q000502:physiology*; D051379:Mice; D009218:Myosins / Q000502:physiology; D013500:Surface Tension
chemical_list: D000199:Actins; D009218:Myosins
keywords: active matter; cell cortex; cell mechanics; non-muscle myosin II; optical trap