Serine 363 is required for nociceptin/orphanin FQ opioid receptor (NOPR) desensitization, internalization, and arrestin signaling

Nancy R. Zhang, William Planer, Edward R. Siuda, Hu Chen Zhao, Lucy Stickler, Steven D. Chang, Madison A. Baird, Yu Qing Cao, Michael R. Bruchas

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

We determined the role of carboxyl-terminal regulation of NOPR (nociceptin, orphanin FQ receptor) signaling and function. We mutated C-terminal serine and threonine residues and examined their role in NOPR trafficking, homologous desensitization, and arrestin-dependent MAPK signaling. The NOPR agonist, nociceptin, caused robust NOPR-YFP receptor internalization, peaking at 30 min. Mutation of serine 337, 346, and 351, had no effect on NOPR internalization. However, mutation of C-terminal threonine 362, serine 363, and threonine 365 blocked nociceptin-induced internalization of NOPR. Furthermore, point mutation of only Ser-363 was sufficient to block NOPR internalization. Homologous desensitization of NOPR-mediated calcium channel blockade and inhibition of cAMP were also shown to require Ser-363. Additionally, NOPR internalization was absent when GRK3, and Arrestin3 were knocked down using siRNA, but not when GRK2 and Arrestin2 were knocked down. We also found that nociceptin-induced NOPR-mediated JNK but not ERK signaling requires Ser-363, GRK3, and Arrestin3. Dominant-positive Arrestin3 but not Arrestin2 was sufficient to rescue NOPR-S363A internalization and JNK signaling. These findings suggest that NOPR function may be regulated by GRK3 phosphorylation of Ser-363 and Arrestin3 and further demonstrates the complex nature of G-protein-dependent and -independent signaling in opioid receptors.

Original languageEnglish
Pages (from-to)42019-42030
Number of pages12
JournalJournal of Biological Chemistry
Volume287
Issue number50
DOIs
StatePublished - Dec 7 2012

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