TY - JOUR
T1 - Differential fMet-Leu-Phe- and platelet-activating factor-induced signaling toward Ral activation in primary human neutrophils
AU - M'Rabet, Laura
AU - Coffer, Paul J.
AU - Wolthuis, Rob M.F.
AU - Zwartkruis, Fried
AU - Koenderman, Leo
AU - Bos, Johannes L.
PY - 1999/7/30
Y1 - 1999/7/30
N2 - We have measured the activation of the small GTPase Ral in-human neutrophils after simulation with fMet-Leu-Phe (fMLP), platelet activating factor (PAF), and granulocyte macrophage-colony stimulating factor and compared it with the activation of two other small GTPases, Ras and Rapl. We found that fMLP and PAF, but not granulocyte macrophage-colony stimulating factor, induce Ral activation. All three stimuli induce the activation of both Ras and Rapl. Utilizing specific inhibitors we demonstrate that fMLP- induced Ral activation is mediated by pertussis toxin-sensitive G-proteins and partially by Src-like kinases, whereas fMLP-induced Ras activation is independent of Src-like kinases. PAF-induced Ral activation is mediated by pertussis toxin-insensitive proteins, Src-like kinases and phosphatidylinositol 3-kinase. Phosphatidylinositol 3-kinase is not involved in PAF-induced Ras activation. The calcium ionophore ionomycin activates Ral, but calcium depletion partially inhibits fMLP- and PAF-induced Ral activation, whereas Ras activation was not affected. In addition, 12-O- tetradecanoylphorbol-13-acetate-induced activation of Ral is completely abolished by inhibitors of protein kinase C, whereas 12-O- tetradecanoylphorbol-13-acetate-induced Ras activation is largely insensitive. We conclude that in neutrophils Ral activation is mediated by multiple pathways, and that fMLP and PAF induce Ral activation differently.
AB - We have measured the activation of the small GTPase Ral in-human neutrophils after simulation with fMet-Leu-Phe (fMLP), platelet activating factor (PAF), and granulocyte macrophage-colony stimulating factor and compared it with the activation of two other small GTPases, Ras and Rapl. We found that fMLP and PAF, but not granulocyte macrophage-colony stimulating factor, induce Ral activation. All three stimuli induce the activation of both Ras and Rapl. Utilizing specific inhibitors we demonstrate that fMLP- induced Ral activation is mediated by pertussis toxin-sensitive G-proteins and partially by Src-like kinases, whereas fMLP-induced Ras activation is independent of Src-like kinases. PAF-induced Ral activation is mediated by pertussis toxin-insensitive proteins, Src-like kinases and phosphatidylinositol 3-kinase. Phosphatidylinositol 3-kinase is not involved in PAF-induced Ras activation. The calcium ionophore ionomycin activates Ral, but calcium depletion partially inhibits fMLP- and PAF-induced Ral activation, whereas Ras activation was not affected. In addition, 12-O- tetradecanoylphorbol-13-acetate-induced activation of Ral is completely abolished by inhibitors of protein kinase C, whereas 12-O- tetradecanoylphorbol-13-acetate-induced Ras activation is largely insensitive. We conclude that in neutrophils Ral activation is mediated by multiple pathways, and that fMLP and PAF induce Ral activation differently.
UR - http://www.scopus.com/inward/record.url?scp=0033618391&partnerID=8YFLogxK
U2 - https://doi.org/10.1074/jbc.274.31.21847
DO - https://doi.org/10.1074/jbc.274.31.21847
M3 - Article
C2 - 10419502
SN - 0021-9258
VL - 274
SP - 21847
EP - 21852
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 31
ER -