title: Geometry regulates traction stresses in adherent cells.
abstract: Cells generate mechanical stresses via the action of myosin motors on the actin cytoskeleton. Although the molecular origin of force generation is well understood, we currently lack an understanding of the regulation of force transmission at cellular length scales. Here, using 3T3 fibroblasts, we experimentally decouple the effects of substrate stiffness, focal adhesion density, and cell morphology to show that the total amount of work a cell does against the substrate to which it is adhered is regulated by the cell spread area alone. Surprisingly, the number of focal adhesions and the substrate stiffness have little effect on regulating the work done on the substrate by the cell. For a given spread area, the local curvature along the cell edge regulates the distribution and magnitude of traction stresses to maintain a constant strain energy. A physical model of the adherent cell as a contractile gel under a uniform boundary tension and mechanically coupled to an elastic substrate quantitatively captures the spatial distribution and magnitude of traction stresses. With a single choice of parameters, this model accurately predicts the cell's mechanical output over a wide range of cell geometries.
authors.affiliation: Institute for Biophysical Dynamics, James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois.
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Oakes
authors.affiliation: Institute for Biophysical Dynamics, James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois; Department of Physics, Syracuse University, Syracuse, New York.
authors.forename: Shiladitya
authors.initials: S
authors.lastname: Banerjee
authors.affiliation: Department of Physics, Syracuse University, Syracuse, New York; Syracuse Biomaterials Institute, Syracuse University, Syracuse, New York.
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Marchetti
authors.affiliation: Institute for Biophysical Dynamics, James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois. Electronic address: gardel@uchicago.edu.
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Gardel
mesh_terms: D016475:3T3 Cells; D000180:Acrylic Resins / Q000737:chemistry; D000818:Animals; D001696:Biomechanical Phenomena; D002448:Cell Adhesion / Q000502:physiology*; D018929:Cell Culture Techniques; D004548:Elasticity; D005347:Fibroblasts / Q000166:cytology* / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D051379:Mice; D018613:Microscopy, Confocal; D008954:Models, Biological; D013314:Stress, Mechanical; D054457:Tissue Scaffolds / Q000737:chemistry; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D000099166:Polyacrylamides