title: Membrane bending modulus and adhesion energy of wild-type and mutant cells of Dictyostelium lacking talin or cortexillins.
abstract: We have employed an interferometric technique for the local measurement of bending modulus, membrane tension, and adhesion energy of motile cells adhering to a substrate. Wild-type and mutant cells of Dictyostelium discoideum were incubated in a flow chamber. The flow-induced deformation of a cell near its adhesion area was determined by quantitative reflection interference contrast microscopy (RICM) and analyzed in terms of the elastic boundary conditions: equilibrium of tensions and bending moments at the contact line. This technique was employed to quantify changes caused by the lack of talin, a protein that couples the actin network to the plasma membrane, or by the lack of cortexillin I or II, two isoforms of the actin-bundling protein cortexillin. Cells lacking either cortexillin I or II exhibited reduced bending moduli of 95 and 160 k(B)T, respectively, as compared to 390 k(B)T, obtained for wild-type cells. No significant difference was found for the adhesion energies of wild-type and cortexillin mutant cells. In cells lacking talin, not only a strongly reduced bending modulus of 70 k(B)T, but also a low adhesion energy one-fourth of that in wild-type cells was measured.
authors.affiliation: Physics Department, Technische Universität München, Garching, Germany. rsimson@physik.tu-muenchen.de
authors.forename: R
authors.initials: R
authors.lastname: Simson
authors.forename: E
authors.initials: E
authors.lastname: Wallraff
authors.forename: J
authors.initials: J
authors.lastname: Faix
authors.forename: J
authors.initials: J
authors.lastname: Niewöhner
authors.forename: G
authors.initials: G
authors.lastname: Gerisch
authors.forename: E
authors.initials: E
authors.lastname: Sackmann
mesh_terms: D000199:Actins / Q000502:physiology; D000818:Animals; D002448:Cell Adhesion; D002462:Cell Membrane / Q000502:physiology*; D004023:Dictyostelium / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D004548:Elasticity; D008433:Mathematics; D008840:Microfilament Proteins / Q000235:genetics / Q000502:physiology*; D015800:Protozoan Proteins; D016608:Talin / Q000235:genetics / Q000502:physiology*
chemical_list: D000199:Actins; D008840:Microfilament Proteins; D015800:Protozoan Proteins; D016608:Talin; C101109:ctxA protein, Dictyostelium discoideum; C101110:ctxB protein, Dictyostelium discoideum