Abstract
We have recently shown that the mu-opioid receptor [MOR1, also termed mu-opioid peptide (MOP) receptor] is associated with the phospholipase D2 (PLD2), a phospholipid-specific phosphodiesterase located in the plasma membrane. We further demonstrated that, in human embryonic kidney (HEK) 293 cells co-expressing MOR1 and PLD2, treatment with (D-Ala2, Me Phe4, Glyol5)enkephalin (DAMGO) led to an increase in PLD2 activity and an induction of receptor endocytosis, whereas morphine, which does not induce opioid receptor endocytosis, failed to activate PLD2. In contrast, a C-terminal splice variant of the mu-opioid receptor (MOR1D, also termed MOP(1D)) exhibited robust endocytosis in response to both DAMGO and morphine treatment. We report here that MOR1D also mediates an agonist-independent (constitutive) PLD2-activation facilitating agonist-induced and constitutive receptor endocytosis. Inhibition of PLD2 activity by over-expression of a dominant negative PLD2 (nPLD2) blocked the constitutive PLD2 activation and impaired the endocytosis of MOR1D receptors. Moreover, we provide evidence that the endocytotic trafficking of the delta-opioid receptor [DOR, also termed delta-opioid peptide (DOP) receptor] and cannabinoid receptor isoform 1 (CB1) is also mediated by a PLD2-dependent pathway. These data indicate the generally important role for PLD2 in the regulation of agonist-dependent and agonist-independent G protein-coupled receptor (GPCR) endocytosis.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Analgesics, Opioid / pharmacology*
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Benzoxazines
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Brefeldin A / pharmacology
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Cell Line
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Cloning, Molecular / methods
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Drug Interactions
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Endocytosis / drug effects
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Endocytosis / physiology*
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Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / pharmacology*
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Enzyme Activation / drug effects
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Enzyme-Linked Immunosorbent Assay / methods
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Gene Expression / physiology
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Humans
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Morphine / pharmacology
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Morpholines / pharmacology
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Naloxone / pharmacology
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Naphthalenes / pharmacology
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Narcotic Antagonists / pharmacology
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Phorbol Esters / pharmacology
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Phospholipase D / physiology*
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Protein Synthesis Inhibitors / pharmacology
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Pyrazoles / pharmacology
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Radioligand Assay / methods
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Receptor, Cannabinoid, CB1 / physiology
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Receptors, G-Protein-Coupled / agonists
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Receptors, G-Protein-Coupled / metabolism*
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Receptors, Opioid, mu / agonists
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Receptors, Opioid, mu / physiology*
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Temperature
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Transfection / methods
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Tritium / pharmacokinetics
Substances
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Analgesics, Opioid
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Benzoxazines
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Morpholines
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Naphthalenes
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Narcotic Antagonists
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Phorbol Esters
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Protein Synthesis Inhibitors
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Pyrazoles
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Receptor, Cannabinoid, CB1
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Receptors, G-Protein-Coupled
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Receptors, Opioid, mu
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Tritium
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Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
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Brefeldin A
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Naloxone
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(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone
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Morphine
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12-O-retinoylphorbol-13-acetate
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phospholipase D2
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Phospholipase D
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AM 281