title: CaMK-II promotes focal adhesion turnover and cell motility by inducing tyrosine dephosphorylation of FAK and paxillin.
abstract: Transient elevations in Ca2+ have previously been shown to promote focal adhesion disassembly and cell motility through an unknown mechanism. In this study, evidence is provided to show that CaMK-II, a Ca2+/calmodulin dependent protein kinase, influences fibroblast adhesion and motility. TIRF microscopy reveals a dynamic population of CaMK-II at the cell surface in migrating cells. Inhibition of CaMK-II with two mechanistically distinct, membrane permeant inhibitors (KN-93 and myr-AIP) freezes lamellipodial dynamics, accelerates spreading on fibronectin, enlarges paxillin-containing focal adhesions and blocks cell motility. In contrast, constitutively active CaMK-II is not found at the cell surface, reduces cell attachment, eliminates paxillin from focal adhesions and decreases the phospho-tyrosine levels of both FAK and paxillin; all of these events can be reversed with myr-AIP. Thus, both CaMK-II inhibition and constitutive activation block cell motility through over-stabilization or destabilization of focal adhesions, respectively. Coupled with the existence of transient Ca2+ elevations and a dynamic CaMK-II population, these findings provide the first direct evidence that CaMK-II enables cell motility by transiently and locally stimulating tyrosine dephosphorylation of focal adhesion proteins to promote focal adhesion turnover.
authors.affiliation: Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, USA.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Easley
authors.forename: Claire M
authors.initials: CM
authors.lastname: Brown
authors.forename: Alan F
authors.initials: AF
authors.lastname: Horwitz
authors.forename: Robert M
authors.initials: RM
authors.lastname: Tombes
mesh_terms: D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D005353:Fibronectins / Q000378:metabolism; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism*; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D015151:Immunoblotting; D051379:Mice; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D051419:Paxillin / Q000378:metabolism*; D010750:Phosphoproteins / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism; D000096926:Benzenesulfonamides
chemical_list: D001596:Benzylamines; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D005353:Fibronectins; D051416:Focal Adhesion Protein-Tyrosine Kinases; D051419:Paxillin; D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D014443:Tyrosine; C072105:KN 93; D000096926:Benzenesulfonamides