title: How cells tiptoe on adhesive surfaces before sticking.
abstract: Cell membranes are studded with protrusions that were thoroughly analyzed with electron microscopy. However, the nanometer-scale three-dimensional motions generated by cell membranes to fit the topography of foreign surfaces and initiate adhesion remain poorly understood. Here, we describe the dynamics of surface deformations displayed by monocytic cells bumping against fibronectin-coated surfaces. We observed membrane undulations with typically 5 nm amplitude and 5-10 s lifetime. Cell membranes behaved as independent units of micrometer size. Cells detected the presence of foreign surfaces at 50 nm separation, resulting in time-dependent amplification of membrane undulations. Molecular contact then ensued with apparent cell-membrane separation of 30-40 nm, and this distance steadily decreased during the following tens of seconds. Contact maturation was associated with in-plane egress of bulky molecules and robust membrane fluctuations. Thus, membrane undulations may be the major determinant of cell sensitivity to substrate topography, outcome of interaction, and initial kinetics of contact extension.
authors.affiliation: INSERM UMR600, CNRS UMR6212, Université de la Mediterranée, 13288 Marseille cedex 09, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Pierres
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Benoliel
authors.forename: Dominique
authors.initials: D
authors.lastname: Touchard
authors.forename: Pierre
authors.initials: P
authors.lastname: Bongrand
mesh_terms: D002448:Cell Adhesion / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D003198:Computer Simulation; D006801:Humans; D008560:Membrane Fluidity / Q000502:physiology*; D008954:Models, Biological; D009000:Monocytes / Q000166:cytology* / Q000502:physiology*