Macrophage colony-stimulating factor induces the expression of mitogen-activated protein kinase phosphatase-1 through a protein kinase C-dependent pathway.
M-CSF triggers the activation of extracellular signal-regulated protein kinases (ERK)-1/2. We show that inhibition of this pathway leads to the arrest of bone marrow macrophages at the G0/G1 phase of the cell cycle without inducing apoptosis. M-CSF induces the transient expression of mitogen-activated protein kinase phosphatase-1 (MKP-1), which correlates with the inactivation of ERK-1/2. Because the time course of ERK activation must be finely controlled to induce cell proliferation, we studied the mechanisms involved in the induction of MKP-1 by M-CSF. Activation of ERK-1/2 is not required for this event. Therefore, M-CSF activates ERK-1/2 and induces MKP-1 expression through different pathways. The use of two protein kinase C (PKC) inhibitors (GF109203X and calphostin C) revealed that M-CSF induces MKP-1 expression through a PKC-dependent pathway. We analyzed the expression of different PKC isoforms in bone marrow macrophages, and we only detected PKCbetaI, PKCepsilon, and PKCzeta. PKCzeta is not inhibited by GF109203X/calphostin C. Of the other two isoforms, PKCepsilon is the best candidate to mediate MKP-1 induction. Prolonged exposure to PMA slightly inhibits MKP-1 expression in response to M-CSF. In bone marrow macrophages, this treatment leads to a complete depletion of PKCbetaI, but only a partial down-regulation of PKCepsilon. Moreover, no translocation of PKCbetaI or PKCzeta from the cytosol to particulate fractions was detected in response to M-CSF, whereas PKCepsilon was constitutively present at the membrane and underwent significant activation in M-CSF-stimulated macrophages. In conclusion, we remark the role of PKC, probably isoform epsilon, in the negative control of ERK-1/2 through the induction of their specific phosphatase.
Valledor
A F
AF
Departament de Fisiologia (Biologia del Macròfag), Facultat de Biologia and Fundació August Pi i Sunyer, Universitat de Barcelona, Spain.
Xaus
J
J
Marquès
L
L
Celada
A
A
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000201:enzymology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D018797:Cell Cycle Proteins; D002454:Cell Differentiation / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D002478:Cells, Cultured; D054638:Dual Specificity Phosphatase 1; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017874:Immediate-Early Proteins / Q000096:biosynthesis*; D007211:Indoles / Q000494:pharmacology; D007424:Intracellular Fluid / Q000201:enzymology; D007527:Isoenzymes / Q000378:metabolism; D016173:Macrophage Colony-Stimulating Factor / Q000502:physiology*; D008264:Macrophages / Q000166:cytology / Q000201:enzymology*; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D019869:Phosphatidylinositol 3-Kinases / Q000096:biosynthesis; D010749:Phosphoprotein Phosphatases; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis*; D015398:Signal Transduction / Q000276:immunology*; D018808:Transcription Factor AP-1 / Q000378:metabolism
D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D017874:Immediate-Early Proteins; D007211:Indoles; D007527:Isoenzymes; D008301:Maleimides; D018808:Transcription Factor AP-1; D016173:Macrophage Colony-Stimulating Factor; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; C517020:Dusp1 protein, mouse; D017027:Protein Tyrosine Phosphatases; C070515:bisindolylmaleimide I