title: The role of actin-binding protein 280 in integrin-dependent mechanoprotection.
abstract: To survive in a mechanically active environment, cells must adapt to variations of applied membrane tension. A collagen-coated magnetic bead model was used to apply forces directly to the actin cytoskeleton through integrin receptors. We demonstrate here that by a calcium-dependent mechanism, human fibroblasts reinforce locally their connection with extracellular adhesion sites by inducing actin assembly and by recruiting actin-binding protein 280 (ABP-280) into cortical adhesion complexes. ABP-280 was phosphorylated on serine residues as a result of force application. This phosphorylation and the force-induced actin reorganization were largely abrogated by inhibitors of protein kinase C. In a human melanoma cell line that does not express ABP-280, actin accumulation could not be induced by force, whereas in stable transfectants expressing ABP-280, force-induced actin accumulation was similar to human fibroblasts. Cortical actin assembly played a role in regulating the activity of stretch-activated, calcium-permeable channels (SAC) since sustained force application desensitized SAC to subsequent force applications, and the decrease in stretch sensitivity was reversed after treatment with cytochalasin D. ABP-280-deficient cells showed a > 90% increase in cell death compared with ABP-280 +ve cells after force application. We conclude that ABP-280 plays an important role in mechanoprotection by reinforcing the membrane cortex and desensitizing SACs.
authors.affiliation: MRC Group in Periodontal Physiology, Faculty of Dentistry, University of Toronto, Ontario, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Glogauer
authors.forename: P
authors.initials: P
authors.lastname: Arora
authors.forename: D
authors.initials: D
authors.lastname: Chou
authors.forename: P A
authors.initials: PA
authors.lastname: Janmey
authors.forename: G P
authors.initials: GP
authors.lastname: Downey
authors.forename: C A
authors.initials: CA
authors.lastname: McCulloch
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002470:Cell Survival; D002478:Cells, Cultured; D003285:Contractile Proteins / Q000378:metabolism*; D015638:Cytochalasin D / Q000378:metabolism; D064448:Filamins; D006801:Humans; D039421:Integrin alpha2; D016023:Integrins / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D016596:Vinculin / Q000378:metabolism
chemical_list: D000199:Actins; D015703:Antigens, CD; D002352:Carrier Proteins; D003285:Contractile Proteins; C578661:FLNC protein, human; D064448:Filamins; D039421:Integrin alpha2; D016023:Integrins; D008840:Microfilament Proteins; D016596:Vinculin; D015638:Cytochalasin D; D002118:Calcium