ADP-ribosylation factor and Rho proteins mediate fMLP-dependent activation of phospholipase D in human neutrophils.
J Biol Chem
; 273(21): 13157-64, 1998 May 22.
Article
em En
| MEDLINE
| ID: mdl-9582356
ABSTRACT
Activation of intact human neutrophils by fMLP stimulates phospholipase D (PLD) by an unknown signaling pathway. The small GTPase, ADP-ribosylation factor (ARF), and Rho proteins regulate the activity of PLD1 directly. Cell permeabilization with streptolysin O leads to loss of cytosolic proteins including ARF but not Rho proteins from the human neutrophils. PLD activation by fMLP is refractory in these cytosol-depleted cells. Readdition of myr-ARF1 but not non-myr-ARF1 restores fMLP-stimulated PLD activity. C3 toxin, which inactivates Rho proteins, reduces the ARF-reconstituted PLD activity, illustrating that although Rho alone does not stimulate PLD activity, it synergizes with ARF. To identify the signaling pathway to ARF and Rho activation by fMLP, we used pertussis toxin and wortmannin to examine the requirement for heterotrimeric G proteins of the Gi family and for phosphoinositide 3-kinase, respectively. PLD activity in both intact cells and the ARF-restored response in cytosol-depleted cells is inhibited by pertussis toxin, indicating a requirement for Gi2/Gi3 protein. In contrast, wortmannin inhibited only fMLP-stimulated PLD activity in intact neutrophils, but it has no effect on myr-ARF1-reconstituted activity. fMLP-stimulated translocation of ARF and Rho proteins to membranes is not inhibited by wortmannin. It is concluded that activation of Gi proteins is obligatory for ARF/Rho activation by fMLP, but activation of phosphoinositide 3-kinase is not required.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfolipase D
/
Proteínas de Ligação ao GTP
/
N-Formilmetionina Leucil-Fenilalanina
/
Neutrófilos
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1998
Tipo de documento:
Article
País de afiliação:
Reino Unido