| J Hypertens. 2005 Jun;23(6):1183-90. |
|
| Stimulation of NADPH oxidase by angiotensin II in human neutrophils
is mediated by ERK, p38 MAP-kinase and cytosolic phospholipase A2. |
|
| Hazan-Halevy I, Levy T, Wolak T, Lubarsky I, Levy R, Paran E |
|
| Hypertension Unit, Soroka Medical Center and Ben-Gurion University,
Beer Sheva, Israel. |
|
| OBJECTIVE: The present research was designed to study the involvement
of ERK and p38 MAP-kinase in cytosolic phospholipase A2 (cPLA2) and
NADPH-oxidase activation by angiotensin II (Ang II) in human neutrophils.
METHODS: NADPH-oxidase activity was measured by reduction of cytochrome
C. cPLA2 activity was measured in cell lysate using sonicated dispersions
of 1-stearoyl-2-[C]arachidonyl phosphatidylcholine. Cells were incubated
with MEK inhibitor UO126 or with p38 MAP-kinase inhibitor SB202190
prior to stimulation with Ang II. Translocation of p47, p67 and cPLA2
and phosphorylation of ERK and p38 MAP-kinase were measured by immunoblot
analysis. RESULTS: Ang II induced a dose-dependent activation of NADPH
oxidase in neutrophils and monocytes as well as in differentiated PLB-985
cells towards neutrophil or monocyte lineages, but not in cPLA2-deficient
differentiated PLB-985 cells. An immediate activation of both ERK and
p38 MAP-kinase and of cPLA2 was induced by Ang II in human neutrophils.
In addition, Ang II induced translocation of the cytosolic oxidase
components, detected by translocation of p47, which preceded the translocation
of cPLA2 induced by this agonist. The p38 MAP-kinase inhibitor SB202190
or the MEK-ERK pathway inhibitor UO126 totally inhibited the activation
of both NADPH oxidase and cPLA2 as well as the translocation of cytosolic
oxidase components and of cPLA2 to the membrane fractions. CONCLUSIONS:
These results suggest that either ERK or p38 MAP-kinase are involved
in the activation of both cPLA2 and NADPH oxidase, and that cPLA2 is
required for activation of the NADPH oxidase by Ang II in human neutrophils. |
