Ectopic expression of human and feline CD9 in a Human B cell line confers ß1 integrin-dependent motility on fibronectin and laminin substrates and enhanced tyrosine phosphorylation

• Author(s) / Creator(s)

  • Shaw, Andrew R. E.
  • Domanska, Agatha
  • Mak, Allan
  • Gilchrist, Anita
  • Dobler, Kelly
  • Visser, Lydia
  • Poppema, Sibrand
  • Fliegel, Larry
  • Letarte, Michelle
  • Willett, Brian J.

• Few molecules have been shown to confer cell motility. Although the motility-arresting properties of anti-CD9 monoclonal antibody (mAb) suggest the transmembrane 4 superfamily (TM4SF) member CD9 can induce a motorgenic signal, gene transfection studies have failed to confirm this hypothesis. We report here that ectopic expression of human CD9 (CD9h) and feline CD9 (CD9f) in the CD9-negative, poorly motile, human B cell line Raji dramatically enhances migration across fibronectin- and laminin-coated polycarbonate filters. Migration of Raji/CD9h and Raji/CD9f on either substrate was inhibited by the anti-CD9 mAb 50H.19 and by the anti-β1 integrin mAb AP-138. Migration of Raji/CD9h on laminin was potently inhibited by the anti-VLA-6 integrin mAb GoH3 and by the anti-VLA-4 integrin mAb 44H6, whereas migration of Raji/CD9h on fibronectin was inhibited only by mAb 44H6. Since CD9h-transfected Raji cells adhered to fibronectin as effectively as mock transfectants, expression of CD9 enhanced motility, but not adhesion. CD9-enhanced migration was inhibited by the protein tyrosine kinase inhibitor herbimycin A suggesting that tyrosine phosphorylation played a role in the generation of a motorgenic signal. Raji/CD9h transfectants adherent to fibronectin expressed 6-fold higher levels of phosphotyrosine than Raji. Raji/CD9f transfectants also phosphorylated proteins on tyrosine more effectively than Raji including a protein of 110 kDa which was phosphorylated on the motility-inducing substrates laminin and fibronectin, but not on bovine serum albumin. Our results support a role for CD9 in the amplification of a motorgenic signal in B cells involving β1 integrins and the activation of protein tyrosine kinases.

• Date created

  1995-01-01

• Subjects / Keywords

  • Antigen
  • Complex
  • Platelet Activation
  • Family
  • P24/Cd9
  • Proteins
  • Molecular-Cloning
  • Association
  • Monoclonal-Antibodies
  • Receptor

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/r3-pgvc-je14

• License

  Attribution 4.0 International