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Actin polymerization induces shedding of FcgammaRIIIb (CD16) from human neutrophils

P J Middelhoven1, J D van Buul, M Kleijer

  • 1Laboratory for Experimental and Clinical Immunology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.

Biochemical and Biophysical Research Communications
|March 2, 1999
PubMed

Insights

Enhanced actin polymerization in neutrophils triggers the shedding of FcgammaRIIIb (CD16) and other cell surface proteins. This actin-dependent process regulates protein ectodomain shedding from neutrophils.

Area of Science:

  • Immunology
  • Cell Biology
  • Biochemistry

Background:

  • FcgammaRIIIb (CD16) is a low-affinity IgG receptor on human neutrophils, linked to the actin cytoskeleton via CR3.
  • Neutrophil activation, apoptosis, and chemotaxis involve actin rearrangements and FcgammaRIIIb shedding.

Purpose of the Study:

  • To investigate the role of the actin cytoskeleton in regulating FcgammaRIIIb shedding from human neutrophils.
  • To determine if actin polymerization directly influences the release of FcgammaRIIIb from the cell surface.

Main Methods:

  • Human neutrophils were treated with jasplakinolide, a peptide that promotes actin polymerization.
  • Time- and dose-dependent effects on FcgammaRIIIb shedding were analyzed.
  • Cell surface expression of other proteins (CD43, CD44, L-selectin) was also monitored.

Main Results:

  • Enhanced actin polymerization significantly induced time- and dose-dependent shedding of FcgammaRIIIb.
  • The shedding effect was not limited to FcgammaRIIIb, as CD43, CD44, and L-selectin expression also decreased.
  • The pathway was sensitive to staurosporine but did not involve PKC or CR3 activation.

Conclusions:

  • The actin cytoskeleton plays a regulatory role in protein ectodomain shedding from human neutrophils.
  • Actin polymerization is a key mechanism controlling the release of FcgammaRIIIb and other surface proteins.

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