κ Opioid Receptor Interacts with Na+/H+-exchanger Regulatory Factor-1/Ezrin-Radixin-Moesin-binding Phosphoprotein-50 (NHERF-1/EBP50) to Stimulate Na+/H+ Exchange Independent of Gi/Go Proteins

Abstract

We previously showed that Na ؉ /H ؉ -exchanger regulatory factor-1/Ezrin-radixin-moesin-binding phosphoprotein-50 (NHERF-1/EBP50) co-immunoprecipitated with the human opioid receptor (hKOR) and that its overexpression blocked the agonist U50,488H-induced hKOR down-regulation by enhancing recycling. Here, we show that glutathione S-transferase (GST)-hKOR Ctail interacted with purified NHERF-1/EBP50, whereas GST or GST-C-tails of or ␦ opioid receptors did not. GST-hKOR C-tail The opioid receptor (KOR)1 is one of the multiple types (at least , ␦, and ) of opioid receptors that mediate pharmacological effects of opioid drugs and physiological actions of endogenous peptides. Activation of opioid receptors in vivo results in many effects, including analgesia (1-3), dysphoria (2-4), and water diuresis (1, 2). At cellular levels, stimulation of opioid receptors activates G i /G o proteins resulting in downstream changes, such as inhibition of adenylyl cyclase, activation of p42/p44 mitogen-activated protein (MAP) kinase, increase in K ϩ conductance, and decrease in Ca 2ϩ conductance (for a review, see Ref. 5). opioid receptors of the human, rat, mouse, and guinea pig have been cloned (for reviews, see Refs. 6 and 7), and the receptors belong to the rhodopsin subfamily of G protein-coupled receptors (GPCRs) (8).PDZ domains were originally identified in the proteins postsynaptic density-95 (PSD-95), discs-large, and zona occludens-1 (ZO-1) as repeats of about 90 amino acids containing the conserved motif Gly-Leu-Gly-Phe. These domains mediate protein-protein interactions by interacting with the last few Cterminal residues of their target proteins (9, 10). Many GPCRs have been shown to interact with PDZ domain-containing proteins, and such interactions play important roles in signal transduction and receptor regulation (for a review, see Ref. 11). Na ϩ /H ϩ exchanger regulatory factor-1 (NHERF-1)/ezrin-radixin-moesin (ERM)-binding phosphoprotein-50 (EBP50) is a PDZ domain-containing protein. Rabbit NHERF-1 was first purified and cloned (12), and the human homolog was subsequently cloned, termed EBP50 (13) or hNHERF (14). The term

Molecular Pharmacology of δ-Opioid Receptors

“…However, DOPr trafficking was not modulated by either a mitogen-activated protein kinase (MAPK) inhibitor or a protein kinase C (PKC) inhibitor (Bie et al, 2010). This latter study also implicated recruitment of a scaffolding protein Na + /H + exchange regulatory factor (NHERF)-1, which was shown to be involved in the sorting of internalized b-2ARs and KOPrs to recycling pathways for resensitization (Huang et al, 2004;Weinman et al, 2006;Hanyaloglu and von Zastrow, 2008). Finally, the appearance of increased functional DOPr induced by chronic morphine was blocked by an inhibitor of protein transport from the ER to the Golgi apparatus (Bie et al, 2010), suggesting that morphine modulates the maturation and sorting of newly synthesized DOPrs.…”

“…M6a overexpression was shown to redirect DOPr to the recycling path (Liang et al, 2008), but it is not yet known whether it has this same effect at endogenous expression levels. NHERF also interacts with DOPr, although with much lower affinity than KOPr (Huang et al, 2004). However, in brainstem neurons, increases in extracellular levels of NGF induce NHERF expression and drive its interaction with DOPr, redirecting receptors from their intracellular stores to the membrane (Bie et al, 2010).…”

GEC1 Interacts with the κ Opioid Receptor and Enhances Expression of the Receptor

“…[7][8][9]. We have demonstrated that activation of opioid receptors stimulates Na ϩ , H ϩ -exchanger 3 activity via NHERF-1/EBP-50 independent of pertussis toxin-sensitive G proteins (10). In this study, we identified proteins interacting with the human opioid receptor (hKOR) by yeast two-hybrid screening of a human brain cDNA library using the cytoplasmic tail (C-tail) as the bait.…”

Ligands Regulate Cell Surface Level of the Human κ Opioid Receptor by Activation-Induced Down-Regulation and Pharmacological Chaperone-Mediated Enhancement: Differential Effects of Nonpeptide and Peptide Agonists

“…After receptor activation, both ␣ and ␤␥ subunits of G proteins recruit downstream signaling effectors to inhibit adenylyl cyclase and voltage-gated Ca 2ϩ channels and to stimulate G proteinactivated inwardly rectifying K ϩ channels, mitogen-activated protein kinase, and phospholipase C␤ (for a review, see Law et al, 2000b). In addition, activation of the KOR regulates Na ϩ ,H ϩ -exchanger 3 via interaction with Ezrin-radixin-moesin-binding phosphoprotein-50/Na ϩ ,H ϩ -exchanger regulatory factor-1 (EBP50/NHERF-1) (Huang et al, 2004).…”