Desensitization of the δ-Opioid Receptor Correlates with Its Phosphorylation in SK-N-BE Cells: Involvement of a G Protein-Coupled Receptor Kinase |
| |
Authors: | Ahmed Hasbi,Jocelyne Polastron,Sté phane Allouche,Laura Stanasila,Dominique Massotte, Philippe Jauzac |
| |
Affiliation: | Laboratoire des Neurosciences, CNRS UMR 6551, Universitéde Caen, Caen, and; Département des Récepteurs et Protéines Membranaires, URA 9050 CNRS, Illkirch Graffenstaden, France |
| |
Abstract: | Abstract: 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 δ-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 δ-opioid receptor, revealed that it corresponded to the δ-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 δ-opioid receptor plays a prominent role in its rapid desensitization. The increase in phosphorylation of the δ-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 δ-opioid receptor, that a close link exists between receptor phosphorylation and agonist-promoted desensitization and that desensitization involves a GRK. |
| |
Keywords: | Phosphorylation δ-Opioid receptor G protein-coupled receptor kinase inhibitor Etorphine Desensitization |
|
|