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Protein kinase A regulates beta2 integrin avidity in neutrophils

Samuel L Jones1

  • 1Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA. sam_jones@ncsu.edu

Journal of Leukocyte Biology
|June 7, 2002
PubMed

Insights

Protein kinase A (PKA) plays a dual role in regulating neutrophil adhesion by modulating beta2 integrin avidity. PKA activation inhibits adhesion to immune complexes, while its inhibition or disruption of PKA anchoring activates adhesion.

Area of Science:

  • Immunology
  • Cell Biology
  • Biochemistry

Background:

  • Neutrophil (PMN) adhesion is critical for immune responses.
  • Beta2 integrin avidity is tightly regulated by intracellular signaling pathways.
  • Protein kinase A (PKA) is a key intracellular signaling enzyme.

Purpose of the Study:

  • To investigate the role of PKA in regulating alphaMbeta2 integrin activation and neutrophil adhesion.
  • To determine if PKA acts as a negative regulator of beta2 integrin avidity.

Main Methods:

  • Studied PMN adhesion to immune complexes (IC) and PMA-stimulated cells.
  • Utilized cAMP elevation, PKA inhibitor (KT5720), and AKAP disruption peptide (Ht31).
  • Assessed beta2 integrin expression and binding of the activating antibody CBRM1/5.

Main Results:

  • Elevated cAMP inhibited PMN adhesion to IC, reversed by KT5720.
  • PKA inhibition activated alphaMbeta2 integrin-dependent adhesion and increased beta2 integrin expression.
  • PKA activity was essential for sustained adhesion; AKAP disruption induced PKC-dependent adhesion.
  • AKAP disruption did not alter beta2 integrin expression or CBRM1/5 binding.

Conclusions:

  • PKA exhibits a dual role in regulating alphaMbeta2 integrin avidity and neutrophil adhesion.
  • PKA activation suppresses adhesion, while PKA inhibition or AKAP disruption can activate it.
  • Distinct mechanisms may underlie PKA-mediated inhibition versus AKAP disruption-induced adhesion.

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