Cytoplasmic tails of beta 1, beta 2, and beta 7 integrins differentially regulate LFA-1 function in K562 cells

M Lub, S J van Vliet, S P Oomen, R A Pieters, M Robinson, C G Figdor, Y van Kooyk

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The beta 2 integrin lymphocyte function-associated antigen 1 (LFA-1) mediates activation-dependent adhesion of lymphocytes. To investigate whether lymphocyte-specific elements are essential for LFA-1 function, we expressed LFA-1 in the erythroleukemic cell line K562, which expresses only the integrin very late antigen 5. We observed that LFA-1-expressing K562 cannot bind to intercellular adhesion molecule 1-coated surfaces when stimulated by phorbol 12-myristate 13-acetate (PMA), whereas the LFA-1-activating antibody KIM185 markedly enhanced adhesion. Because the endogenously expressed beta 1 integrin very late antigen 5 is readily activated by PMA, we investigated the role of the cytoplasmic domain of distinct beta subunits in regulating LFA-1 function. Transfection of chimeric LFA-1 receptors in K562 cells reveals that replacement of the beta 2 cytoplasmic tail with the beta 1 but not the beta 7 cytoplasmic tail completely restores PMA responsiveness of LFA-1, whereas a beta 2 cytoplasmic deletion mutant of LFA-1 is constitutively active. Both deletion of the beta 2 cytoplasmic tail or replacement by the beta 1 cytoplasmic tail alters the localization of LFA-1 into clusters, thereby regulating LFA-1 activation and LFA-1-mediated adhesion to intercellular adhesion molecule 1. These data demonstrate that distinct signaling routes activate beta 1 and beta 2 integrins through the beta-chain and hint at the involvement of lymphocyte-specific signal transduction elements in beta 2 and beta 7 integrin activation that are absent in the nonlymphocytic cell line K562.

Original languageEnglish
Pages (from-to)719-28
Number of pages10
JournalMolecular biology of the cell
Issue number4
Publication statusPublished - Apr 1997


  • Amino Acid Sequence
  • Binding Sites
  • CD18 Antigens/drug effects
  • Cell Adhesion/physiology
  • Cell Membrane/metabolism
  • Cytoplasm/metabolism
  • Fibronectins/metabolism
  • Humans
  • Integrin beta Chains
  • Integrin beta1/drug effects
  • Integrins/drug effects
  • Intercellular Adhesion Molecule-1/metabolism
  • Leukemia, Erythroblastic, Acute/drug therapy
  • Leukemia, Experimental
  • Lymphocyte Function-Associated Antigen-1/drug effects
  • Lymphocytes/physiology
  • Molecular Sequence Data
  • Recombinant Proteins/drug effects
  • Signal Transduction
  • Tetradecanoylphorbol Acetate/pharmacology
  • Tumor Cells, Cultured

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