Orphanin FQ/Nociceptin Activates Nuclear Factor Kappa B

Endogenous neuropeptide orphanin FQ/nociceptin (OFQ/N) and its receptor, nociceptin orphanin FQ peptide receptor (NOPr), play a modulatory role throughout the body including nociceptive sensitivity, motor function, spatial learning, and the immune system. NOPr is an inhibitory G protein coupled receptor (GPCR) that modulates expression and release of inflammatory mediators from immune cells and in the CNS. Inhibitory GPCRs have been shown to activate the immune and central nervous system regulator, nuclear factor kappa B (NF kappa B), whose family consists of several subunits. When activated, NF kappa B translocates to the nucleus and can modify transcription. To determine if OFQ/N modulates NF kappa B activity, SH-SY5Y human neuroblastoma cells were treated with OFQ/N and assessed for changes in nuclear accumulation, DNA binding, and transcriptional activation. For the first time, we show that OFQ/N increases the nuclear accumulation (1.9-2.8-fold) and the DNA binding of NF kappa B (2.9-fold) by 2 h as determined by immunoblotting and electromobility shift assay, respectively. OFQ/N induction of NF kappa B binding to DNA is protein kinase C-dependent and NOPr-specific. OFQ/N stimulated binding of both NF kappa B p50 and p65 subunits to their consensus binding site on DNA. OFQ/N also induces transcriptional activation of an NF kappa B reporter gene 2.2-fold by 2 h with an EC50 of 6.3 nM. This activation of NF kappa B by OFQ/N suggests a likely mechanism for its modulation of the central nervous and immune systems.