Linked regulation of motility and integrin function in activated migrating neutrophils revealed by interference in remodelling of the cytoskeleton.

Neutrophils migrate rapidly by co-ordinating regulation of their beta2-integrin adhesion with turnover of filamentous F-actin. The seven-protein Arp2/3 complex regulates actin polymerisation upon activation by proteins of the WASP-family. To investigate links between actin polymerisation, adhesion, and migration, we used a novel osmotic-shock method to load neutrophils with peptides: (1). WASP-WA and Scar-WA (which incorporate the actin- and Arp2/3-binding regions of WASP and Scar1), to compete with endogenous WASP-family members; (2). proline rich motifs (PRM) from the ActA protein of L. monocytogenes or from vinculin, which bind vasodilator-stimulated phosphoprotein (VASP), a regulator of cytoskeleton assembly. In a flow system, rolling-adherent neutrophils were stimulated with formyl tri-peptide. This caused rapid immobilisation, followed by migration with increasing velocity, supported by activated beta2-integrin CD11b/CD18. Loading ActA PRM (but not vinculin PRM) caused concentration-dependent reduction in migration velocity. At the highest concentration, unstimulated neutrophils had elevated F-actin and were rigid, but could not change their F-actin content or shape upon stimulation. Scar-WA also caused marked reduction in migration rate, but WASP-WA had a lesser effect. Scar-WA did not modify activation-dependent formation of F-actin or change in shape. However, a reduction in rate of downregulation of integrin adhesion appeared to contribute to impaired migration. These studies show that interference in cytoskeletal reorganisation that follows activation in neutrophils, can impair regulation of integrin function as well as motility. They also suggest a role of the Arp2/3 complex and WASP-family in co-ordinating actin polymerisation and integrin function in migrating neutrophils.

Anderson SI ，Behrendt B ，Machesky LM ，Insall RH ，Nash GB ... -  《cell motility and the cytoskeleton》

Actin polymerisation regulates integrin-mediated adhesion as well as rigidity of neutrophils.

Sheikh S ，Gratzer WB ，Pinder JC ，Nash GB ... -  《BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS》

Interaction of WASP/Scar proteins with actin and vertebrate Arp2/3 complex.

Marchand JB ，Kaiser DA ，Pollard TD ，Higgs HN ... -  《NATURE CELL BIOLOGY》

Regulation of VASP serine 157 phosphorylation in human neutrophils after stimulation by a chemoattractant.

Eckert RE ，Jones SL 《JOURNAL OF LEUKOCYTE BIOLOGY》

ActA and human zyxin harbour Arp2/3-independent actin-polymerization activity.

Fradelizi J ，Noireaux V ，Plastino J ，Menichi B ，Louvard D ，Sykes C ，Golsteyn RM ，Friederich E ... -  《NATURE CELL BIOLOGY》