Ca2+/calmodulin-dependent transcriptional activation of delta-opioid receptor gene expression induced by membrane depolarization in NG108-15 cells.
Regulation of gene expression is one of the mechanisms by which neuronal activity elicits long-term changes in neuronal phenotype and function. Although activity-dependent induction of immediate-early genes has been extensively studied, much less is known about the late-response genes. We have investigated the activity-dependent regulation of delta-opioid receptor (DOR) mRNA levels in NG108-15 cells. Transsynaptic activation was mimicked by depolarization with 55 mM KCl or veratridine. Both treatments lead to a time-dependent increase of DOR mRNA levels. Ca2+ entry through L-type voltage-dependent Ca2+ channels activated by depolarization appears to be involved, because L-type channel blockers reduced the induction of DOR expression. Ca2+ binding to calmodulin is the next step in the signal transduction pathway, because a calmodulin antagonist, W7, reduced the effect of veratridine. A selective inhibitor of calmodulin kinases (KN-62) and cyclosporin, an inhibitor of calcineurin, also antagonized the depolarization-induced increase in DOR mRNA levels, which indicates that both calcium/calmodulin-dependent enzymes are involved in the activity-dependent induction of DOR gene expression. Induction of DOR gene expression by an activity-dependent increase in intracellular Ca2+ concentration may serve as a feedback regulatory mechanism because activation of DOR leads to hyperpolarization and lower excitability of neurons.
Buzas
B
B
Department of Pharmacology, Uniformed Services University, Bethesda, Maryland 20814, USA.
Rosenberger
J
J
Cox
B M
BM
D001665:Binding Sites / Q000502:physiology; D019703:Calcineurin / Q000502:physiology; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology; D002147:Calmodulin / Q000502:physiology*; D004594:Electrophysiology; D004789:Enzyme Activation / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology*; D008566:Membranes / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D017465:Receptors, Opioid, delta / Q000235:genetics*; D013997:Time Factors; D014158:Transcription, Genetic / Q000502:physiology*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000502:physiology; D014701:Veratridine / Q000494:pharmacology
D015220:Calcium Channels; D002147:Calmodulin; D012333:RNA, Messenger; D017465:Receptors, Opioid, delta; D014701:Veratridine; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019703:Calcineurin; D002118:Calcium