Yd. Cui et al., FMLP-induced formation of F-actin in HL60 cells is dependent on PI3-K but not on intracellular Ca2+, PKC, ERK or p38 MAPK, INFLAMM RES, 49(12), 2000, pp. 684-691
Objective and Design: To further understand the mechanisms of signal transd
uction pathways for the formation of F-actin (polymerization of actin) and
the activation of NADPH oxidase in phagocytic cells, the effects of various
inhibitors on them were studied.
Materials and Methods: Differentiated HL60 cells were studied to examine th
eir N-formyl-methionyl-leucyl-phenyl-alanine (fMLP)-stimulated formation of
F-actin and activation of NADPH oxidase following treatment with various i
nhibitors. These included a protein kinase C (PKC) inhibitor (GF 109203X),
a phosphatidylinositide 3 kinase (PI3-K) inhibitor (wortmannin), an extrace
llular response kinase (ERK) inhibitor (PD 98059), a p38 mitogen-activated
protein kinase (MAPK) inhibitor (SB 203580) and an intracellular Ca2+-chela
tor (BAPTA-AM).
Results: The treatment with wortmannin suppressed the formation of F-actin,
with less suppression of the activation of NADPH oxidase. BAPTA-AM and GF
109203X did not attenuate the formation of F-actin but completely inhibited
the activation of NADPH oxidase. PD 98059 and SE 203580 partially inhibite
d the activation of NADPH oxidase without influence on the formation of F-a
ctin. Furthermore, wortmannin but not BAPTA-AM and GF 109203X inhibited the
fMLP-induced activation of Akt, which is known to regulate NADPH oxidase.
Conclusions: These results suggest that the formation of F-actin is depende
nt on PI3-K and independent of PKC, ERK and p38 MAPK as well as the increas
e in intracellular Ca2+, whereas the activation of NADPH oxidase is partly
dependent on ERK, p38 MAPK, Akt regulated by PI3-K, and strongly dependent
on the activation of PKC and the increase in intracellular Ca2+.