Cyclooxygenase-2 is a neuronal target gene of NF-κB

BACKGROUND: NF-κB is implicated in gene regulation involved in neuronal survival, inflammmatory response and cancer. There are relatively few neuronal target genes of NF-κB characterized. RESULTS: We have identified the neuronal cyclooxygenase-2 (COX-2) as a NF-κB target gene. In organotypic hippocampal slice cultures constitutive NF-κB activity was detected, which was correlated with high anti-COX-2 immunoreactivity. Aspirin a frequently used painkiller inhibits neuronal NF-κB activity in organotypic cultures resulting in a strong inhibition of the NF-κB target gene COX-2. Based on these findings, the transcriptional regulation of COX-2 by NF-κB was investigated. Transient transfections showed a significant increase of COX-2 promoter activity upon stimulation with PMA, an effect which could be obtained also by cotransfection of the NF-κB subunits p65 and p50. In the murine neuroblastoma cell line NB-4, which is characterized by constitutive NF-κB activity, COX-2 promoter activity could not be further increased with PMA or TNF. Constitutive promoter activity could be repressed upon cotransfection of the inhibitory subunit IκB-α. EMSA and mutational analysis conferred the regulatory NF-κB activity to the promoter distal κB-site in the human COX-2 promoter. CONCLUSIONS: NF-κB regulates neuronal COX-2 gene expression, and acts as an upstream target of Aspirin. This extends Aspirin's mode of action from a covalent modification of COX-2 to the upstream regulation of COX-2 gene expression in neurons.