Desensitization of the delta-opioid receptor correlates with its phosphorylation in SK-N-BE cells: involvement of a G protein-coupled receptor kinase.
Phosphorylation of G protein-coupled receptors is considered an important step during their desensitization. In SK-N-BE cells, recently presented as a pertinent model for the studies of the human delta-opioid receptor, pretreatment with the opioid agonist etorphine increased time-dependently the rate of phosphorylation of a 51-kDa membrane protein. Immunological characterization of this protein with an antibody, raised against the amino-terminal region of the cloned human delta-opioid receptor, revealed that it corresponded to the delta-opioid receptor. During prolonged treatment with etorphine, phosphorylation increased as early as 15 min to reach a maximum within 1 h. Phosphorylation and desensitization of adenylyl cyclase inhibition paralleled closely and okadaic acid inhibited the resensitization, a result strongly suggesting that phosphorylation of the delta-opioid receptor plays a prominent role in its rapid desensitization. The increase in phosphorylation of the delta-opioid receptor, as well as its desensitization, was not affected by H7, an inhibitor of protein kinase A and protein kinase C, but was drastically reduced by heparin or Zn2+, known to act as G protein-coupled receptor kinase (GRK) inhibitors. These results are the first to show, on endogenously expressed human delta-opioid receptor, that a close link exists between receptor phosphorylation and agonist-promoted desensitization and that desensitization involves a GRK.
Hasbi
A
A
Laboratoire des Neurosciences, CNRS UMR 6551, Université de Caen, France.
Polastron
J
J
Allouche
S
S
Stanasila
L
L
Massotte
D
D
Jauzac
P
P
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005048:Etorphine / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D008970:Molecular Weight; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism / Q000502:physiology*; D017465:Receptors, Opioid, delta / Q000187:drug effects* / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D015032:Zinc / Q000494:pharmacology
D000701:Analgesics, Opioid; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D017465:Receptors, Opioid, delta; D005048:Etorphine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D006493:Heparin; D020794:Receptor Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins; D015032:Zinc