Macrophage-colony-stimulating factor-induced activation of extracellular-regulated kinase involves phosphatidylinositol 3-kinase and reactive oxygen species in human monocytes.
We previously reported that activation of the phosphatidylinositol (PI) 3-kinase pathway was important in M-CSF-induced monocyte survival. Because M-CSF also induces activation of the mitogen-activated protein (MAP) kinase extracellular-regulated kinase (Erk), we focused on dissecting the mechanism used by M-CSF to induce Erk activation in human monocytes. We found that, in addition to the MAP/Erk kinase inhibitor PD098059, the PI 3-kinase inhibitors LY294002 and wortmannin both suppressed Erk activation in M-CSF-treated monocytes, suggesting that 3-phosphorylated products of PI 3-kinase played a role in Erk activation. Investigating the biochemical pathways regulated by PI 3-kinase to activate Erk, we found that, in response to M-CSF, normal human monocytes induced reactive oxygen species (ROS), which were suppressed by the PI 3-kinase inhibitor wortmannin but not by the solvent control DMSO or the MAP/Erk kinase inhibitor PD098059. We next found that, in the absence of M-CSF, ROS could induce Erk activation in human monocytes. Exogenous H(2)O(2) induced Erk activation in human monocytes, which was suppressed by exogenous catalase. To determine whether ROS induced by M-CSF played a role in Erk activation, we found that N-acetylcysteine and diphenyleneiodonium both suppressed Erk activation in M-CSF-treated monocytes. Erk activation by M-CSF also seemed to play a role in cellular survival in monocytes. These data suggest that, in M-CSF-stimulated human monocytes, PI 3-kinase products and ROS production play a role in Erk activation and monocyte survival.
Bhatt
Nitin Y
NY
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus 43210, USA.
Kelley
Todd W
TW
Khramtsov
Valery V
VV
Wang
Yijie
Y
Lam
Gregory K
GK
Clanton
Thomas L
TL
Marsh
Clay B
CB
D000730:Androstadienes / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D066298:In Vitro Techniques; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017382:Reactive Oxygen Species / Q000378:metabolism; D000077191:Wortmannin
D000730:Androstadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D005419:Flavonoids; D006861:Hydrogen Peroxide; D016173:Macrophage Colony-Stimulating Factor; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017382:Reactive Oxygen Species; D000077191:Wortmannin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one