Orphanin FQ/Nociceptin-Mediated Desensitization of Opioid Receptor-Like 1 Receptor and μ Opioid Receptors Involves Protein Kinase C: A Molecular Mechanism for Heterologous Cross-Talk

Abstract

Morphine tolerance in vivo is reduced following blockade of the orphanin FQ/nociceptin (OFQ/N)/opioid receptor-like 1 (ORL1) receptor system, suggesting that OFQ/N contributes to the development of morphine tolerance. We previously reported that a 60-min activation of ORL1 receptors natively expressed in BE(2)-C cells desensitized both and ORL1 receptor-mediated inhibition of cAMP. Investigating the mechanism(s) of OFQ/N-mediated and ORL1 receptor cross-talk, we found that pretreatment with the protein kinase C inhibitor, chelerythrine chloride (1 M), blocked OFQ/N-mediated homologous desensitization of ORL1 and heterologous desensitization of opioid receptors. Furthermore, depletion of PKC by 12-O-tetradecanoylphorbol-13-acetate exposure (48 h, 1 M) also prevented OFQ/N-mediated and ORL1 desensitization. OFQ/N pretreatment resulted in translocation of PKC-␣, G proteincoupled receptor kinase 2 (GRK2) and GRK3 from the cytosol to the membrane, and this translocation was also blocked by chelerythrine. Reduction of GRK2 and GRK3 levels by antisense, but not sense DNA treatment blocks ORL1 and receptor desensitization. This suggests that PKC-␣ is required for GRK2 and GRK3 translocation to the membrane, where GRK can inactivate ORL1 and opioid receptors upon rechallenge with the appropriate agonist. Our results demonstrate for the first time the involvement of conventional PKC isozymes in OFQ/N-induced -ORL1 cross-talk, and represent a possible mechanism for OFQ/N-induced anti-opioid actions.Orphanin FQ/nociceptin (OFQ/N), an exquisitely selective agonist at the opioid receptor-like 1 (ORL1) receptor, modulates both behavioral (nociception, anxiety, learning, reward) and immune (cell proliferation) responses (Harrison and Grandy, 2000;Peluso et al., 2001). Although ORL1 and OFQ/N share greater than 40% homology with other opioid receptors and endogenous opioid peptides, many of their actions are anti-opioid in nature (Harrison and Grandy, 2000). One cellular mechanism for their anti-opioid effect is attributed, at least partially, to actions of OFQ/N on different populations of neurons in the brainstem (Pan et al., 2000). The molecular basis of their anti-opioid effects still remains to be determined, but heterologous cross-talk is a possibility since and ORL1 receptors are colocalized on several cell populations within the descending analgesic pathway (Connor et al

μ-Opioid-Induced Desensitization of Opioid Receptor-Like 1 and μ-Opioid Receptors: Differential Intracellular Signaling Determines Receptor Sensitivity

“…DAMGO pretreatment desensitized only -mediated stimulation of ERK1/2. However, in a human neuroblastoma cell line natively expressing -and ORL1 subtypes [BE(2)-C], short-term pretreatment with OFQ/N or DAMGO desensitized -and ORL1 opioid receptor-mediated inhibition of cAMP accumulation (Mandyam et al, 2000(Mandyam et al, , 2002. These data indicate that the ability of -opioid receptor agonists to heterologously regulate ORL1 function varies between cell types.…”

“…Phosphodiester antisense or sense ODNs (Ͼ99% purity) were dissolved in sterile water to a concentration of 3 mM. The ODN designated GRK2/3 antisense: 5Ј ACC GCC TCC AGG TCC GCC AT 3Ј or its corresponding sense strand were added to the BE(2)-C (10 M) or SH-SY5Y (30 M) cells and incubated for 60 h in media deprived of serum (Mandyam et al, 2002). To selectively down-regulate GRK2 or GRK3, cells received 1 M GRK2 antisense ODN, 5Ј-CTC CAG GTC CGC CAT CTT-3Ј (72 h; Aiyar et al, 2000); GRK3 antisense ODN, 5Ј-TCC AGT GTC TGC TTT CCT-3Ј (48 h; Thakker and Standifer, 2002); or their corresponding sense ODNs.…”

Modification of Nociception and Morphine Tolerance by the Selective Opiate Receptor-Like Orphan Receptor Antagonist (–)-cis-1-Methyl-7-[[4-(2,6-dichlorophenyl)piperidin-1-yl]methyl]-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ol (SB-612111)

“…An alternative view, which builds upon the observation of -opioid and ORL-1 receptor coexpression on the same cells, uses evidence of receptor cross talk and heterologous receptor desensitization to explain the opposing actions of -opioid and ORL-1 receptor activation. For instance, Mandyam et al (2002) have shown that ORL-1 receptor activation can cause desensitization of -opioid receptors expressed on the same cell by stimulating translocation of protein kinase C isozymes to the cell membrane. Thus, an ORL-1 antagonist would be expected to prevent desensitization of the -opioid receptor resulting from nociceptin-mediated ORL-1 receptor activation, and thereby potentiate the action of morphine.…”

Nociceptin/Orphanin FQ Receptor Structure, Signaling, Ligands, Functions, and Interactions with Opioid Systems

“…In BE(2)-C cells, short treatment with N/OFQ induces translocation of PKCa, GRK2, and GRK3 to the plasma membrane. The increase in GRK2 levels at the plasma membrane resulted in enhanced DAMGO-mediated mu receptor phosphorylation and a resultant increased desensitization (Mandyam et al, 2002;Ozsoy et al, 2005). Prolonged N/OFQ treatment reduced the ability of mu agonists to inhibit cAMP accumulation in BE(2)-C and SH-SY5Y cells (Thakker and Standifer, 2002a), although N/OFQ treatment had no effect on the ability of mu agonists to activate ERK1/2 (Thakker and Standifer, 2002b).…”

“…The human, mouse and rat NOP receptors contain multiple serine, tyrosine, and threonine sites within their intracellular loops and C termini that are suitable for GRK or protein kinase A/C phosphorylation (Zhang et al, 2012a;Donica et al, 2013). GRK regulation of NOP receptors has been shown to act at multiple C-terminal sites (Mandyam et al, 2002). GRKs phosphorylate serine residues 334 and 335 on the C-terminal tail of the rat NOP receptor (337 in the human) and mutations of these residues significantly reduce the amount of receptor desensitization (Wang et al, 2006).…”