The Role of Sequestration in G Protein-coupled Receptor Resensitization

Krueger, Kathleen M.; Daaka, Yehia; Pitcher, Julie A.; Lefkowitz, Robert J.

doi:10.1074/jbc.272.1.5

Cited by 315 publications

(157 citation statements)

References 27 publications

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“…Studies of other G protein-coupled receptors indicate that ligand-dependent internalization can play multiple, important roles in the modulation of cell signaling (32)(33)(34)(35). Thus the remarkable selectivity of opioid receptor internalization demonstrated in the present study may be of great importance for understanding type-specific differences in the physiological regulation of opioid receptors following activation by relatively nonselective opiate analgesic drugs.…”

Section: Receptor Constructmentioning

confidence: 86%

δ and κ Opioid Receptors Are Differentially Regulated by Dynamin-dependent Endocytosis When Activated by the Same Alkaloid Agonist

Chu

Murray²,

Lissin

et al. 1997

Journal of Biological Chemistry

137

114

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Many alkaloid drugs used as analgesics activate multiple opioid receptors. Mechanisms that distinguish the actions of these drugs on the regulation of individual , ␦, and receptors are not understood. We have observed that individual cloned opioid receptors differ significantly in their regulation by rapid endocytosis in the presence of alkaloid drug etorphine, a potent agonist of , ␦, and opioid receptors. Internalization of epitopetagged ␦ opioid receptors from the plasma membrane is detectable within 10 min in the presence of etorphine. In contrast, receptors expressed in the same cells remain in the plasma membrane and are not internalized for >60 min, even when cells are exposed to saturating concentrations of etorphine. The rapid internalization of ␦ receptors is specifically inhibited in cells expressing K44E mutant dynamin I, suggesting that type-specific internalization of opioid receptors is mediated by clathrin-coated pits. Examination of a series of chimeric mutant /␦ receptors indicates that at least two receptor domains, including the highly divergent carboxyl-terminal cytoplasmic tail, determine the type specificity of this endocytic mechanism. We conclude that structurally homologous opioid receptors are differentially sorted by clathrin-mediated endocytosis following activation by the same agonist ligand. These studies identify a fundamental mechanism of receptor regulation mediating type-specific effects of analgesic drugs that activate more than one type of opioid receptor.Structurally homologous -, ␦-, and -type opioid receptors are conserved in mammals and signal via similar heterotrimeric G proteins (1-3). These receptors are activated both by endogenously expressed opioid peptides and by structurally distinct alkaloid agonists, which are clinically important analgesics and drugs of abuse (4). Although many alkaloid analgesics activate more than one type of opioid receptor at clinically relevant concentrations, significant differences in the regulation of ␦, , and receptor-mediated processes by individual agonists have been observed (5-7). Molecular mechanisms underlying this functional specificity, even in the presence of relatively nonselective opiate drugs, are not understood. We have identified a mechanism of receptor regulation that mediates type-specific regulation of opioid receptors following activation by the same alkaloid agonist.Previous studies have identified multiple processes that regulate opioid receptors. Ligand-dependent phosphorylation of cytoplasmic residues is thought to modulate the functional activity of opioid receptors within minutes after activation (8, 9). Agonist-induced down-regulation, which is associated with a gradual translocation of receptors from the plasma membrane to lysosomes, occurs over a more prolonged time course (10 -12). A distinguishable rapid endocytic process, which occurs within several minutes after receptor activation and is not associated with degradation of receptors, has been shown recently to regulate ␦ and opioid receptors (13-15). Indi...

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Section: Receptor Constructmentioning

confidence: 86%

δ and κ Opioid Receptors Are Differentially Regulated by Dynamin-dependent Endocytosis When Activated by the Same Alkaloid Agonist

Chu

Murray²,

Lissin

et al. 1997

Journal of Biological Chemistry

137

114

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“…3b). The attenuated receptor response is reversed upon agonist removal (19). We next measured the time required for the MAPK signal to become resensitized.…”

Section: Resultsmentioning

confidence: 99%

A Mitogen-activated Protein Kinase Pathway Is Required for μ-Opioid Receptor Desensitization

Polakiewicz

Schieferl

Dorner

et al. 1998

Journal of Biological Chemistry

129

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The -opioid receptor mediates not only the beneficial painkilling effects of opiates like morphine but also the detrimental effects of chronic exposure such as tolerance and dependence. Different studies have linked tolerance to opioid receptor desensitization. Agonist activation of the -opioid receptor stimulates a mitogenactivated protein kinase (MAPK) activity, but the functional significance of this pathway remains unclear. We have focused on the MAPK signaling cascade to study -opioid receptor desensitization. We report that inhibition of the MAPK pathway blocks desensitization of -opioid receptor signaling as well as the loss of receptor density due to internalization. Our results suggest that a feedback signal emanating from the MAPK cascade is required for -opioid receptor desensitization.Agonists for the -opioid receptor are the therapeutic choice in the management of severe acute and chronic pain despite the potential development of tolerance, dependence, and addiction. The mechanisms of tolerance, defined as the diminishing effect of the drug in response to chronic exposure, are not fully understood. It has been postulated that receptor desensitization and down-regulation could be associated with aspects of tolerance in vivo (1). Opioid receptors undergo homologous desensitization upon continuous or repeated agonist exposure in a fashion similar to other G protein-coupled receptors (GPCR) 1 (2-4). Desensitization of the -opioid receptor involves agonistdependent phosphorylation of the receptor, most likely by a member of the family of G-coupled receptor protein kinases (GRKs) (4, 5). According to this model, upon phosphorylation and uncoupling from the G protein, the receptor is bound to ␤-arrestins and internalized into endosomes, reducing the number of receptors available at the cell surface for further agonist binding (6, 7).Desensitization of the -opioid receptor has been mainly described as the attenuated reduction of forskolin-stimulated cAMP levels in response to the agonist (2-4). However, other signaling pathways might also be desensitized upon prolonged agonist exposure. GPCRs can trigger a G␤␥-mediated activation of a phosphoinositide 3-kinase (PI3K)/Ras-dependent MAPK signaling pathway (8, 9). Opioid receptors stimulate MAPK activity as well, although the components of this signaling cascade have not been fully described (10 -12). In this report we have examined the role of the MAPK (Erk1/2) signaling pathway on -opioid receptor desensitization. This pathway, which involves the activation of a phosphatidylinositol 3-kinase activity as well as Raf and MEK1/2, is essential for -opioid receptor desensitization. EXPERIMENTAL PROCEDURESReagents-[D-Ala 2 ,N-Me-Phe 4 ,Gly 5 -ol]enkephalin (DAMGO), dermorphin, morphine, Met-enkephalin, naloxone, D-Pen 2 ,D-Pen 5 -enkephalin (DPDPE), lysophosphatidic acid (LPA), pertussis toxin, cycloheximide, forskolin, and isobutylmethylxanthine (IBMX) were from Sigma. Wortmannin and LY294002 were from Calbiochem. Antibodies that recognize only the phosphorylated...

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“…Furthermore, subsequent dephosphorylation of the receptor by protein phosphatases may play a role in receptor resensitization (Krueger et al, 1997). Previous studies on the /3 2-adrenergic (Yu et al, 1993;Pippig …”

Section: Role Of Receptor Dephosphorylation In Resensitizationmentioning

confidence: 99%

“…It is envisaged that receptor activation stimulates receptor phosphorylation and endocytosis, which in turn causes uncoupling of the receptor from its G protein. Receptors are dephosphorylated in an endocytotic compartment that has a high level of phosphatase activity (Krueger et al, 1997), and they are ultimately recycled back to the plasma membrane ready for another round of activation. There is evidence in support of this hypothesis at least for some G protein-coupled receptors, such as the ß 2-adrenergic receptor (Yu et al, 1993;Pippig et al, 1995) and the neurokinin receptors (Garland et al, 1996).…”

mentioning

confidence: 99%

Involvement of Receptor Cycling and Receptor Reserve in Resensitization of Muscarinic Responses in SH‐SY5Y Human Neuroblastoma Cells

Szekeres¹,

Koenig²,

Edwardson³

1998

Journal of Neurochemistry

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Preexposure of SH-SY5Y cells to the muscarinic agonist carbachol caused a rapid desensitization of subsequent carbachol-stimulated intracellular Ca 2~re-sponses and a slower decrease in the number of receptors at the plasma membrane. Desensitization (to 30% of the control response) was maximal after 1 min of exposure to agonist, whereas the number of cell surface receptors reached a minimum (33% of control) only after 5 min. Following agonist washout, the recovery of response was complete within 12 mm, whereas the recovery of surface receptor number reached a plateau at 65% of control after 30 min. Treatment with inhibitors of endocytosis (concanavalin A) or recycling (nigericin) did not affect rapid desensitization but did decrease resensitization, suggesting that receptor cycling is involved in resensitization. Experiments with the irreversible antagonist propylbenzilylcholine mustard demonstrated that the receptor reserve for the Ca2~response to 1 mM carbachol is -..50%. Removal of this receptor reserve led to a decrease in the rate of resensitization. We propose that the existence of a receptor reserve might explain The poor correlation between functional response and surface receptor number, and that one of its roles might be to permit rapid resensitization after a significant agonist-induced decrease in surface receptor number. The purpose of receptor cycling might be to allow dephosphorylation (and reactivation) of receptors that have become phosphorylated (and inactivated) in response to agonist stimulation, because the protein phosphatase inhibitor calyculin A significantly reduced resensitization.

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The Role of Sequestration in G Protein-coupled Receptor Resensitization

Cited by 315 publications

References 27 publications

δ and κ Opioid Receptors Are Differentially Regulated by Dynamin-dependent Endocytosis When Activated by the Same Alkaloid Agonist

δ and κ Opioid Receptors Are Differentially Regulated by Dynamin-dependent Endocytosis When Activated by the Same Alkaloid Agonist

A Mitogen-activated Protein Kinase Pathway Is Required for μ-Opioid Receptor Desensitization

Involvement of Receptor Cycling and Receptor Reserve in Resensitization of Muscarinic Responses in SH‐SY5Y Human Neuroblastoma Cells

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