S. Sheikh et al., ACTIN POLYMERIZATION REGULATES INTEGRIN-MEDIATED ADHESION AS WELL AS RIGIDITY OF NEUTROPHILS, Biochemical and biophysical research communications, 238(3), 1997, pp. 910-915
Activation of adherent neutrophils causes them to convert from selecti
n-mediated rolling to integrin-mediated immobilisation and migration,
Migration is known to depend on formation and redistribution of filame
ntous (F) actin, but although immobilisation in seconds parallels earl
y cortical actin polymerisation, no link has been proven. We tested th
e effect. of the actin-polymerising agent jasplakinolide (10 mu M) on
adhesive and mechanical properties of neutrophils. Pretreated cells we
re able to adhere and roll on immobilised platelets in a how-based adh
esion assay, but whereas untreated rolling cells became immobilised in
seconds when chemo tactic formyl peptide (fMLP, 0.1 mu M) was superfu
sed over them, the cells treated with jasplakinolide continued rolling
. Pretreatment with jasplakinolide also blocked de novo expression of
integrin CD11b and shape change which otherwise occurred in minutes af
ter treatment with fMLP. Jasplakinolide directly caused actin polymeri
sation within neutrophils, evidenced by a marked increase in rigidity
(resistance to aspiration into a 5 mu m micropipette) and increase in
association of actin with the Triton-insoluble cytoskeleton. These res
ults indicate that rearrangement of the actin cytoskeleton regulates i
ntegrin-mediated adhesion of activated neutrophils, as well as their m
igration and mechanical properties. (C) 1997 Academic Press.