Signal pathway regulation of interleukin-8-induced actin polymerization in neutrophils.
Interleukin-8 (IL-8), a recently described peptide cytokine, is a neutrophil chemoattractant and activator that exerts effects similar to fMLP, yet their receptors and their roles in pathophysiology differ. The effect of IL-8 on the neutrophil cytoskeleton has not been well studied; therefore, we compared and contrasted the effects of IL-8 and fMLP on neutrophil actin conformation and on the signal pathway regulation of actin responses. IL-8 caused a rapid, dose-dependent increase in neutrophil F-actin content within 30 seconds. The maximum increase was twofold. These changes were accompanied by the development of F-actin-rich pseudopods, as noted with fluorescence microscopy and scanning electron microscopy. Selected biochemical inhibitors were used to study the regulation of the IL-8-induced actin changes. Incubation of neutrophils with 2 micrograms/mL pertussis toxin resulted in a 67% inhibition of the IL-8-induced F-actin increase. The protein kinase C (PKC) inhibitors, staurosporine and H7, did not inhibit the increase in F-actin caused by IL-8. IL-8 caused a rapid increase in neutrophil intracellular calcium that could be completely inhibited by the chelating agent 1,2-bis(o-aminophenoxy)ethane-N,N-N',N'-tetraacetic acid (BAPTA). However, BAPTA-treated neutrophils retained the ability to increase F-actin in response to IL-8. Similar results were seen with fMLP, indicating that, similar to fMLP, the IL-8-induced actin response is mediated through pertussis-toxin-sensitive G-proteins but is neither dependent on PKC nor increases in cytosolic calcium. Thus, although IL-8 and fMLP exert their effects on neutrophils through different receptors, the signal transduction pathways used and the effects on actin conformation and pseudopod formation are similar.
Sham
R L
RL
University of Rochester School of Medicine and Dentistry, NY.
Phatak
P D
PD
Ihne
T P
TP
Abboud
C N
CN
Packman
C H
CH
D000199:Actins / Q000032:analysis / Q000378:metabolism*; D002118:Calcium / Q000502:physiology; D006801:Humans; D016209:Interleukin-8 / Q000494:pharmacology*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin; D011108:Polymers / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000199:Actins; D016209:Interleukin-8; D011108:Polymers; D010566:Virulence Factors, Bordetella; D009240:N-Formylmethionine Leucyl-Phenylalanine; D037342:Pertussis Toxin; D011493:Protein Kinase C; D002118:Calcium