title: Essential role for calcium waves in migration of human vascular smooth muscle cells.
abstract: Vascular smooth muscle cell (SMC) migration is characterized by extension of the lamellipodia at the leading edge, lamellipodial attachment to substrate, and release of the rear (uropod) of the cell, all of which enable forward movement. However, little is known regarding the role of intracellular cytosolic Ca(2+) concentration ([Ca(2+)](i)) in coordinating these distinct activities of migrating SMCs. The objective of our study was to determine whether regional changes of Ca(2+) orchestrate the migratory cycle in human vascular SMCs. We carried out Ca(2+) imaging using digital fluorescence microscopy of fura-2 loaded human smooth muscle cells. We found that motile SMCs exhibited Ca(2+) waves that characteristically swept from the rear of polarized cells toward the leading edge. Ca(2+) waves were less evident in nonpolarized, stationary cells, although acute stimulation of these SMCs with the agonists platelet-derived growth factor-BB or histamine could elicit transient rise of [Ca(2+)](i). To investigate a role for Ca(2+) waves in the migratory cycle, we loaded cells with the Ca(2+) chelator BAPTA, which abolished Ca(2+) waves and significantly reduced retraction, supporting a causal role for Ca(2+) in initiation of retraction. However, lamellipod motility was still evident in BAPTA-loaded cells. The incidence of Ca(2+) oscillations was reduced when Ca(2+) release from intracellular stores was disrupted with the sarcoplasmic reticulum Ca(2+)-ATPase inhibitor thapsigargin or by treatment with the inositol 1,4,5-trisphosphate receptor blocker 2-aminoethoxy-diphenyl borate or xestospongin C, implicating Ca(2+) stores in generation of waves. We conclude that Ca(2+) waves are essential for migration of human vascular SMCs and can encode cell polarity.
authors.affiliation: Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Espinosa-Tanguma
authors.forename: Caroline
authors.initials: C
authors.lastname: O'Neil
authors.forename: Tom
authors.initials: T
authors.lastname: Chrones
authors.forename: J Geoffrey
authors.initials: JG
authors.lastname: Pickering
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Sims
mesh_terms: D000704:Analysis of Variance; D000077214:Becaplermin; D001896:Boron Compounds / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D016764:Cell Polarity; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006632:Histamine / Q000378:metabolism; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism; D047028:Macrocyclic Compounds / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D010080:Oxazoles / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D011554:Pseudopodia / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors
chemical_list: D001896:Boron Compounds; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D053496:Inositol 1,4,5-Trisphosphate Receptors; D047028:Macrocyclic Compounds; D010080:Oxazoles; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; C511704:xestospongin C; D000077214:Becaplermin; D004533:Egtazic Acid; D019284:Thapsigargin; D006632:Histamine; C109986:2-aminoethoxydiphenyl borate; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid