Mitogen-activated protein kinase kinase negatively modulates ciliary neurotrophic factor-activated choline acetyltransferase gene expression.
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.
Mellott
Tiffany
T
Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA 02118, USA.
Lopez-Coviella
Ignacio
I
Blusztajn
Jan Krzysztof
JK
Berse
Brygida
B
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
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