title: MEK-1/2 inhibition prevents 5-lipoxygenase translocation in N-formylpeptide-challenged human neutrophils.
abstract: In order to elucidate the role of mitogen-activated protein kinase kinase (MEK-1/2) in 5-lipoxygenase (5-LO) activation we studied the N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced 5-LO translocation in human blood neutrophils (PMNs). In non-primed, Ca(2+)-repleted PMNs, fMLP consistently stimulated MEK-1/2 phosphorylation, but induced 5-LO translocation and product formation (430+/-128 pmol; SEM, n=13) only in 13 of 18 PMN preparations from different healthy donors. In fMLP-responsive cells, the MEK-1/2 inhibitor PD098059 (50 microM) attenuated MEK phosphorylation and abolished 5-LO activation at the translocation step. The fMLP-mediated 5-LO product formation was also sensitive to MEK inhibition by U0126 and to p38 inhibition by SB203580. But in contrast to PD098059, U0126 at 10 microM and SB203580 at 20-50 microM impaired 5-LO activity in the cell-free assay setting, suggesting direct actions of higher concentrations of U0126 and SB203580 on 5-LO apart from MEK and p38 inhibition, respectively. These data show that fMLP initiates 5-LO product formation in non-primed, Ca(2+)-repleted human blood PMNs from healthy donors, and that MEK signaling is pivotal, but not sufficient for 5-LO activation in response to the receptor agonist fMLP.
authors.affiliation: Department of Pharmacology, Institute of Pharmaceutical Sciences, University of Tuebingen, Auf der Morgenstelle 8, D-72076, Tübingen, Germany.
authors.forename: S E
authors.initials: SE
authors.lastname: Boden
authors.forename: T
authors.initials: T
authors.lastname: Bertsche
authors.forename: H P
authors.initials: HP
authors.lastname: Ammon
authors.forename: H
authors.initials: H
authors.lastname: Safayhi
mesh_terms: D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D002070:Butadienes / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002474:Cell-Free System; D004789:Enzyme Activation / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology
chemical_list: D002070:Butadienes; D005419:Flavonoids; D007093:Imidazoles; D009570:Nitriles; D011725:Pyridines; C113580:U 0126; D000001:Calcimycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D001094:Arachidonate 5-Lipoxygenase; C482128:MAP2K2 protein, human; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium