title: Partitioning of cortical and deep cytoskeleton responses from transient magnetic bead twisting.
abstract: We attempted to estimate in living adherent epithelial alveolar cells, the degree of structural and mechanical heterogeneity by considering two individualized cytoskeleton components, i.e., a submembranous "cortical" cytoskeleton and a "deep" cytoskeleton (CSK). F-actin structure characterizing each CSK component was visualized from spatial reconstructions at low and high density, respectively, especially in a 10-microm-cubic neighborhood including the bead. Specific mechanical properties (Young elastic and viscous modulus E and n) were revealed after partitioning the magnetic twisting cytometry response using a double viscoelastic "solid" model with asymmetric plastic relaxation. Results show that the cortical CSK response is a faster (tau1 < or = 0.7 s), softer (E1: 63-109 Pa), moderately viscous (n1: 7- 18 Pas), slightly tensed, and easily damaged structure compared to the deep CSK structure which appears slower (tau2 approximately 1/2 min), stiffer (E2: 95-204 Pa), highly viscous (n2: 760-1967 Pa s), more tensed, and fully elastic, while exhibiting a larger stress hardening behavior. Adding drug depolymerizing actin filaments decreased predominantly the deep CSK stiffness. By contrast, an agent altering cell-matrix interactions affected essentially the cortical CSK stiffness. We concluded that partitioning the CSK within cortical and deep structures is largely consistent with their respective functional activities.
authors.affiliation: Inserm UMR S 492, Physiopathologie et Thérapeutique Respiratoires, Institut Supérieur des Biosciences de Paris, Université Paris-12, 94010, Créteil, France.
authors.forename: Valérie M
authors.initials: VM
authors.lastname: Laurent
authors.forename: Redouane
authors.initials: R
authors.lastname: Fodil
authors.forename: Patrick
authors.initials: P
authors.lastname: Cañadas
authors.forename: Sophie
authors.initials: S
authors.lastname: Féréol
authors.forename: Bruno
authors.initials: B
authors.lastname: Louis
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Planus
authors.forename: Daniel
authors.initials: D
authors.lastname: Isabey
mesh_terms: D000199:Actins / Q000502:physiology*; D002460:Cell Line; D003198:Computer Simulation; D003599:Cytoskeleton / Q000502:physiology*; D004548:Elasticity; D006801:Humans; D008280:Magnetics; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008863:Microspheres; D008954:Models, Biological; D010812:Physical Stimulation / Q000295:instrumentation / Q000379:methods*; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000502:physiology*; D020545:Respiratory Mucosa / Q000166:cytology* / Q000502:physiology*; D012399:Rotation; D013329:Structure-Activity Relationship; D019415:Torque; D014783:Viscosity
chemical_list: D000199:Actins