L-plastin peptide activation of alpha(v)beta(3)-mediated adhesion requires integrin conformational change and actin filament disassembly.
L-plastin (LPL) is a leukocyte actin binding protein previously implicated in the activation of the integrin alpha(M)beta(2) on polymorphonuclear neutrophils. To determine the role for LPL in integrin activation, K562 cell adhesion to vitronectin via alpha(v)beta(3), a well-studied model for activable integrins, was examined. Cell permeant versions of peptides based on the N-terminal sequence of LPL and the LPL headpiece domain both activated alpha(v)beta(3)-mediated adhesion. In contrast to adhesion induced by treatment with phorbol 12-myristate 13-acetate (PMA), LPL peptide-activated adhesion was independent of integrin beta(3) cytoplasmic domain tyrosines and was not inhibited by cytochalasin D. Also in contrast to PMA, LPL peptides synergized with RGD ligand or Mn(2+) for generation of a conformational change in alpha(v)beta(3) associated with the high affinity state of the integrin, as determined by binding of a ligand-induced binding site antibody. Although LPL and ligand showed synergy for ligand-induced binding site expression when actin depolymerization was inhibited by jasplakinolide, LPL peptide-induced adhesion was inhibited. Thus, both actin depolymerization and ligand-induced integrin conformational change are required for LPL peptide-induced adhesion. We hypothesize that the critical steps of increased integrin diffusion and affinity enhancement may be linked via modulation of the function of the actin binding protein L-plastin.
Program in Molecular Cell Biology, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Chen
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Brown
D008841:Actin Cytoskeleton / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology; D001665:Binding Sites; D002448:Cell Adhesion; D002460:Cell Line; D002469:Cell Separation; D015638:Cytochalasin D / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D047630:Depsipeptides; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D016023:Integrins / Q000737:chemistry*; D008024:Ligands; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D008954:Models, Biological; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D009842:Oligopeptides / Q000378:metabolism / Q000494:pharmacology; D010455:Peptides / Q000378:metabolism; D010456:Peptides, Cyclic / Q000494:pharmacology; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D019030:Receptors, Vitronectin / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D018631:ras Proteins
D000970:Antineoplastic Agents; D018076:DNA, Complementary; D047630:Depsipeptides; D016023:Integrins; D008024:Ligands; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D009842:Oligopeptides; D010455:Peptides; D010456:Peptides, Cyclic; D010750:Phosphoproteins; C084355:RRAD protein, human; D019030:Receptors, Vitronectin; D011993:Recombinant Fusion Proteins; C026742:plastin; C057531:jasplakinolide; D015638:Cytochalasin D; C047981:arginyl-glycyl-aspartic acid; D018631:ras Proteins; D013755:Tetradecanoylphorbol Acetate