title: p38 MAP kinase inhibits neutrophil development through phosphorylation of C/EBPalpha on serine 21.
abstract: Many extracellular stimuli regulate growth, survival, and differentiation responses through activation of the dual specificity mitogen activated protein kinase (MAPK) kinase three (MKK3) and its downstream effector p38 MAPK. Using CD34+ hematopoietic progenitor cells, here we describe a novel role for MKK3-p38MAPK in the regulation of myelopoiesis. Inhibition of p38MAPK utilizing the pharmacological inhibitor SB203580, enhanced neutrophil development ex vivo, but conversely reduced eosinophil differentiation. In contrast, constitutive activation of MKK3 dramatically inhibited neutrophil differentiation. Transplantation of beta2-microglobulin(-/-) nonobese diabetic/severe combined immune deficient (NOD/SCID) mice with CD34+ cells ectopically expressing constitutively active MKK3 resulted in reduced neutrophil differentiation in vivo, whereas eosinophil development was enhanced. Inhibitory phosphorylation of CCAAT/enhancer binding protein alpha (C/EBPalpha) on serine 21 was induced upon activation of p38MAPK. Moreover, ectopic expression of a non-phosphorylatable C/EBPalpha mutant was sufficient to abrogate MKK3-induced inhibition of neutrophil development. Furthermore, treatment of CD34+ progenitors from patients with severe congenital neutropenia with SB203580 restored neutrophil development. These results establish a novel role for MKK3-p38MAPK in the regulation of lineage choices during myelopoiesis through modulation of C/EBPalpha activity. This signaling module may thus provide an important therapeutic target in the treatment of bone marrow failure.
authors: Molecular Immunology Lab, Department of Immunology, University Medical Center, Utrecht, The Netherlands.
authors: Christian R
authors: CR
authors: Geest
authors: Miranda
authors: M
authors: Buitenhuis
authors: Annemieke G
authors: AG
authors: Laarhoven
authors: Marc B
authors: MB
authors: Bierings
authors: Marrie C A
authors: MC
authors: Bruin
authors: Edo
authors: E
authors: Vellenga
authors: Paul J
authors: PJ
authors: Coffer
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004804:Eosinophils / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007150:Immunohistochemistry; D048371:MAP Kinase Kinase 3 / Q000378:metabolism; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D038042:Myelopoiesis / Q000187:drug effects; D009503:Neutropenia / Q000378:metabolism / Q000473:pathology; D009504:Neutrophils / Q000166:cytology* / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D016897:Respiratory Burst; D012694:Serine / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011725:Pyridines; D012694:Serine; D048051:p38 Mitogen-Activated Protein Kinases; D048371:MAP Kinase Kinase 3; C093642:SB 203580