p21-Activated kinase (PAK) regulates cytoskeletal reorganization and directional migration in human neutrophils

PLoS One. 2013 Sep 3;8(9):e73063. doi: 10.1371/journal.pone.0073063. eCollection 2013.

Abstract

Neutrophils serve as a first line of defense in innate immunity owing in part to their ability to rapidly migrate towards chemotactic factors derived from invading pathogens. As a migratory function, neutrophil chemotaxis is regulated by the Rho family of small GTPases. However, the mechanisms by which Rho GTPases orchestrate cytoskeletal dynamics in migrating neutrophils remain ill-defined. In this study, we characterized the role of p21-activated kinase (PAK) downstream of Rho GTPases in cytoskeletal remodeling and chemotactic processes of human neutrophils. We found that PAK activation occurred upon stimulation of neutrophils with f-Met-Leu-Phe (fMLP), and PAK accumulated at the actin-rich leading edge of stimulated neutrophils, suggesting a role for PAK in Rac-dependent actin remodeling. Treatment with the pharmacological PAK inhibitor, PF3758309, abrogated the integrity of RhoA-mediated actomyosin contractility and surface adhesion. Moreover, inhibition of PAK activity impaired neutrophil morphological polarization and directional migration under a gradient of fMLP, and was associated with dysregulated Ca(2+) signaling. These results suggest that PAK serves as an important effector of Rho-family GTPases in neutrophil cytoskeletal reorganization, and plays a key role in driving efficient directional migration of human neutrophils.

Publication types

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

MeSH terms

  • Blotting, Western
  • Chemotaxis, Leukocyte*
  • Cytoskeleton / metabolism*
  • Enzyme Activation
  • Fluorescent Antibody Technique
  • Humans
  • Microscopy, Fluorescence
  • N-Formylmethionine Leucyl-Phenylalanine / pharmacology
  • Neutrophils / drug effects
  • Neutrophils / enzymology
  • Neutrophils / metabolism*
  • Protein Transport
  • p21-Activated Kinases / metabolism*

Substances

  • N-Formylmethionine Leucyl-Phenylalanine
  • p21-Activated Kinases