Dioxin-mediated up-regulation of aryl hydrocarbon receptor target genes is dependent on the calcium/calmodulin/CaMKIalpha pathway.
Regulation of genes targeted by the ligand-activated aryl hydrocarbon receptor (AhR) has been shown to be controlled by calcium (Ca(2+)) changes induced by AhR agonists such as the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The present study was designed to characterize this link between Ca(2+) and the AhR pathway. We report that fast elevation of intracellular Ca(2+) in TCDD-exposed mammary MCF-7 cells was associated with transient enhanced activity of the Ca(2+)/calmodulin (CaM)-dependent protein kinase (CaMK) pathway. Chemical inhibition of this pathway using the CaM antagonist W7 or the CaMK inhibitor KN-93 strongly reduced TCDD-mediated induction of the AhR target gene CYP1A1. Small interfering RNA (siRNA)-mediated knockdown expression of CaMKIalpha, one of the CaMK isoforms, similarly prevented CYP1A1 up-regulation. Both KN-93 and siRNA targeting CaMKIalpha were found to abolish TCDD-mediated activation of CYP1A1 promoter and TCDD-triggered nuclear import of AhR, a crucial step of the AhR signaling pathway. TCDD-mediated inductions of various AhR targets, such as the drug metabolizing CYP1B1, the cytokine interleukin-1beta, the chemokines interleukin-8 and CCL1, the adhesion molecule beta7 integrin, and the AhR repressor, were also prevented by KN-93 in human macrophages. Taken together, these data identified the Ca(2+)/CaM/CaMKIalpha pathway as an important contributing factor to AhR-mediated genomic response.
Monteiro
Patricia
P
INSERM U620, Université de Rennes1, Faculté des Sciences Pharmaceutiques et Biologiques, IFR140, 2 Avenue du Professeur Léon Bernard, 35043 Rennes Cedex, France.
Gilot
David
D
Le Ferrec
Eric
E
Rauch
Claudine
C
Lagadic-Gossmann
Dominique
D
Fardel
Olivier
O
D001596:Benzylamines / Q000494:pharmacology; D001943:Breast Neoplasms / Q000473:pathology; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1 / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D045744:Cell Line, Tumor; D019363:Cytochrome P-450 CYP1A1 / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D004785:Environmental Pollutants; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D017930:Genes, Reporter; D006801:Humans; D049410:Luciferases, Renilla / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D034741:RNA, Small Interfering / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013223:Statistics as Topic; D013449:Sulfonamides / Q000494:pharmacology; D015854:Up-Regulation; D000096926:Benzenesulfonamides
D001596:Benzylamines; D002118:Calcium; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D002147:Calmodulin; D019363:Cytochrome P-450 CYP1A1; D004785:Environmental Pollutants; D004791:Enzyme Inhibitors; D049410:Luciferases, Renilla; D000072317:Polychlorinated Dibenzodioxins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018336:Receptors, Aryl Hydrocarbon; D013449:Sulfonamides; C072105:KN 93; D000096926:Benzenesulfonamides; C017967:W 7; C517596:CAMK1 protein, human