Src-family kinases mediate an outside-in signal necessary for beta2 integrins to achieve full activation and sustain firm adhesion of polymorphonuclear leucocytes tethered on E-selectin

Biochem J. 2006 May 15;396(1):89-98. doi: 10.1042/BJ20051924.


In cell suspensions subjected to high-shear rotatory motion, human PMN (polymorphonuclear cells) adhered to E-selectin-expressing CHO (Chinese-hamster ovary) cells (CHO-E), and formed homotypic aggregates when challenged by E-selectin-IgG fusion protein, by a mechanism that involved beta2 integrins. Both heterotypic and homotypic PMN adhesion was accompanied by tyrosine phosphorylation of a 110 kDa protein (P110). This event was prevented by blocking anti-(beta2 integrin) antibodies and by inhibitors of Src-family kinases, suggesting that it was part of an 'outside-in' signalling that was initiated by integrin engagement. Interestingly, Src-family kinase inhibitors prevented beta2-integrin-mediated (i) homotypic PMN adhesion triggered by E-selectin-IgG, (ii) heterotypic CHO-E/PMN adhesion in mixed-cell suspensions, and (iii) firm adhesion of PMN to CHO-E monolayers under physiological flow. Similarly to PMN treated with Src-family kinase inhibitors, PMN from hck-/-fgr-/- and hck-/-fgr-/-lyn-/- mice showed significant impairment of beta2-integrin-mediated adhesion to CHO-E. Moreover, the expression of beta2 integrin activation epitopes at the sites of cell-cell contact in CHO-E/PMN conjugates was abolished by Src-family kinase inhibitors. One component of P110 was identified as the FAK (focal adhesion kinase) Pyk2 (proline-rich tyrosine kinase 2), which was phosphorylated in a beta2 integrin- and Src-family-kinase-dependent manner. Thus, Src-family kinases, and perhaps Pyk2, mediate a signal necessary for beta2 integrin function in PMN tethered by E-selectin.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD18 Antigens / physiology*
  • CHO Cells
  • Cell Adhesion / physiology*
  • Cricetinae
  • Cricetulus
  • E-Selectin / physiology*
  • Egtazic Acid / pharmacology
  • Flow Cytometry
  • Focal Adhesion Kinase 2 / physiology
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neutrophils / cytology*
  • Phosphorylation
  • Protein Processing, Post-Translational
  • Pyrazoles / pharmacology
  • Pyrimidines / pharmacology
  • Recombinant Fusion Proteins / physiology
  • Rheology
  • Signal Transduction / physiology*
  • Stress, Mechanical
  • Transfection
  • src-Family Kinases / antagonists & inhibitors
  • src-Family Kinases / physiology*


  • 4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine
  • CD18 Antigens
  • E-Selectin
  • Pyrazoles
  • Pyrimidines
  • Recombinant Fusion Proteins
  • Egtazic Acid
  • Focal Adhesion Kinase 2
  • src-Family Kinases