title: Mitogen-activated protein kinase kinase negatively modulates ciliary neurotrophic factor-activated choline acetyltransferase gene expression.
abstract: The expression of the choline acetyltransferase (ChAT) enzyme that synthesizes the neurotransmitter acetylcholine (ACh) is upregulated by ciliary neurotrophic factor (CNTF). We studied the involvement of the mitogen-activated protein kinase (MAPK) pathway in regulating ChAT expression in a murine septal cell line. Surprisingly, we found that PD98059 and U0126, two structurally distinct inhibitors of MAPK kinase (MEK1), increased both basal and CNTF-induced ACh production. Transient transfections with ChAT promoter-luciferase reporter construct demonstrated synergy between PD98059 and CNTF at the transcriptional level. Moreover, in cotransfection studies, overexpression of constitutively activated MEK1 completely abrogated the CNTF-mediated induction of the reporter. Blocking MEK1 did not significantly alter CNTF-induced Tyr705 phosphorylation of the principal mediator of the CNTF pathway, the transcription factor Stat3. However, PD98059 inhibited Ser727 phosphorylation of Stat3, demonstrating that the latter is MEK1-dependent. Taken together, these results indicate that activation of the MEK1/MAPK pathway inhibits the CNTF-mediated stimulation of ChAT expression, possibly as a part of a feedback mechanism.
authors.affiliation: Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Mellott
authors.forename: Ignacio
authors.initials: I
authors.lastname: Lopez-Coviella
authors.forename: Jan Krzysztof
authors.initials: JK
authors.lastname: Blusztajn
authors.forename: Brygida
authors.initials: B
authors.lastname: Berse
mesh_terms: D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002460:Cell Line; D002795:Choline O-Acetyltransferase / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D020934:Ciliary Neurotrophic Factor / Q000378:metabolism* / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D053613:Janus Kinase 1; D048369:MAP Kinase Kinase 1; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000187:drug effects / Q000378:metabolism; D050796:STAT3 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D002070:Butadienes; D020934:Ciliary Neurotrophic Factor; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009570:Nitriles; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D020032:Tyrphostins; C113580:U 0126; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D002795:Choline O-Acetyltransferase; D011505:Protein-Tyrosine Kinases; C507905:Jak1 protein, mouse; D053613:Janus Kinase 1; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one