title: Rapid stiffening of integrin receptor-actin linkages in endothelial cells stimulated with thrombin: a magnetic bead microrheology study.
abstract: By using magnetic bead microrheology we study the effect of inflammatory agents and toxins on the viscoelastic moduli of endothelial cell plasma membranes in real time. Viscoelastic response curves were acquired by applying short force pulses of ~500 pN to fibronectin-coated magnetic beads attached to the surface membrane of endothelial cells. Upon addition of thrombin, a rapid stiffening of the membrane was observed within 5 s, followed by recovery of the initial deformability within 2 min. By using specific inhibitors, two known pathways by which thrombin induces actin reorganization in endothelial cells, namely activation of Ca2+-calmodulin-dependent myosin light chain kinase and stimulation of Rho/Rho-kinase, were excluded as possible causes of the stiffening effect. Interestingly, the cytotoxic necrotizing factor of Escherichia coli, a toxin which, in addition to Rho, activates the GTPases Rac and CDC42Hs, also induced a dramatic stiffening effect, suggesting that the stiffening may be mediated through a Rac- or Cdc42Hs-dependent pathway. This work demonstrates that magnetic bead microrheometry is not only a powerful tool to determine the absolute viscoelastic moduli of the composite cell plasma membrane, but also a valuable tool to study in real time the effect of drugs or toxins on the viscoelastic parameters of the plasma membrane.
authors.affiliation: Physik Department E22 (Biophysics group), Technische Universität München, D-85748 Garching, D-80336 München, Germany. dbausch@physik.tu-muenchen.de
authors.forename: A R
authors.initials: AR
authors.lastname: Bausch
authors.forename: U
authors.initials: U
authors.lastname: Hellerer
authors.forename: M
authors.initials: M
authors.lastname: Essler
authors.forename: M
authors.initials: M
authors.lastname: Aepfelbacher
authors.forename: E
authors.initials: E
authors.lastname: Sackmann
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000378:metabolism*; D001427:Bacterial Toxins / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004548:Elasticity / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018056:Hemorheology; D006801:Humans; D016023:Integrins / Q000737:chemistry* / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids / Q000494:pharmacology; D008280:Magnetics; D008856:Microscopy, Fluorescence; D008863:Microspheres; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013917:Thrombin / Q000494:pharmacology*; D014471:Umbilical Veins; D014783:Viscosity / Q000187:drug effects; D054460:rho-Associated Kinases
chemical_list: D000199:Actins; D001427:Bacterial Toxins; D016023:Integrins; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids; D003094:Collagen; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D013917:Thrombin; D002118:Calcium