Prodynorphin gene expression relates to NF-kappa B factors.
The prodynorphin gene contains several kappa B motifs, suggesting that kappa B-specific DNA-binding factors may regulate its expression. Prodynorphin is known to be expressed in human tumor cell lines [Geiger et al., Regul. Peptides, 34 (1991) 181-188] and we report here that several DNA-binding factors of the NF-kappa B/c-Rel-family are present in the same cells. Three main kappa B-specific factors, presumably a p50 homodimer, NF-kappa B which is a p50/p65 heterodimer and a p65/c-Rel heterodimer were identified using an electromobility shift assay (EMSA), immunoabsorption and UV cross-linking experiments. Minor factors consisting of a novel kappa B-specific protein of about 125 kDa (p125) or being hetero-oligomeric, composed of p125 and either of three other subunits, namely p50, p65 and c-Rel, were also identified. The homo-oligomer of p125 may be identical to the kappa B-specific factor BETA, previously found only in brain [Korner et al., Neuron, 3 (1989) 563-572]. Comparison of prodynorphin mRNA levels with levels of the kappa B-specific DNA-binding factors revealed a negative correlation with the level of p50 homodimer, and a positive correlation with the ratio of the levels of p65/c-Rel to NF-kappa B. No association was found with proenkephalin mRNA levels which were significant in only one cell line. The p50 homodimer, but not p65/c-Rel and NF-kappa B, bound specifically to a DNA-motif within the dynorphin A-encoding gene sequence. This sequence is located in exon 4 and similar to the consensus kappa B-sequence. The dynorphin A-encoding sequence may represent an intragenic target for the p50 homodimer, which when bound to the sequence suppresses transcription.
Department of Drug Dependence Research, Karolinska Institute, Stockholm, Sweden.
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D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002822:Choriocarcinoma; D004745:Enkephalins / Q000096:biosynthesis*; D015870:Gene Expression; D006801:Humans; D008175:Lung Neoplasms; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D009447:Neuroblastoma; D009838:Oligodeoxyribonucleotides; D015345:Oligonucleotide Probes; D011498:Protein Precursors / Q000096:biosynthesis*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D020569:Proto-Oncogene Proteins c-rel; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D013552:Swine; D014407:Tumor Cells, Cultured
D004745:Enkephalins; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D015345:Oligonucleotide Probes; D011498:Protein Precursors; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; C033660:preproenkephalin