Actin-associated proteins in human neutrophils: identification and reorganization upon cell activation.
The neutrophil cytoskeleton, especially the actin network, is thought to play a crucial role in neutrophil migration. However, little is known on the modulation of this network by actin-associated proteins. We have demonstrated the presence of immuno-reactive forms of alpha-actinin (an actin cross-linking and bundling protein) and vinculin (a putative actin-membrane linker) in human neutrophils using specific antibodies to chicken gizzard vinculin and bovine epithelial alpha-actinin. In contrast, talin, another putative actin-membrane linker protein, could not be detected in significant amounts in human neutrophils using a polyclonal antibody raised against chicken gizzard talin, which reacted with human platelet and lymphocyte talin. We have also analyzed the vinculin and alpha-actinin content of Triton X-100 insoluble cytoskeletons, isolated from resting and activated neutrophils. A small amount of alpha-actinin was already associated with the cytoskeleton of resting cells. Addition of chemotactic peptide to the cells rapidly increased the alpha-actinin content of the cytoskeletons 1.6 to 7-fold. This rapid increase was followed by a slower decrease to a lower level which, after 30 min of stimulation, was still significantly higher than that of control cells. The time-course of the association of alpha-actinin with the cytoskeleton paralleled that of actin association. This stimulus-induced rearrangement of cellular alpha-actin may thus play an important role in determining the structure of actin networks in motile neutrophils. Vinculin in contrast could not be detected in significant amounts in the Triton X-100-insoluble neutrophil cytoskeleton, not even after prolonged stimulation of the cells by chemotactic peptide.
Niggli
V
V
Department of Pathology, University of Bern/Switzerland.
Jenni
V
V
D000185:Actinin / Q000032:analysis*; D015153:Blotting, Western; D003598:Cytoskeletal Proteins / Q000032:analysis*; D003599:Cytoskeleton / Q000032:analysis; D003720:Densitometry; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D009504:Neutrophils / Q000032:analysis* / Q000502:physiology; D009842:Oligopeptides / Q000494:pharmacology; D011092:Polyethylene Glycols; D016608:Talin; D016596:Vinculin
D003598:Cytoskeletal Proteins; D009842:Oligopeptides; D016608:Talin; D000185:Actinin; D016596:Vinculin; D011092:Polyethylene Glycols; C021642:F-chemotactic peptide