Beta‐arrestin 1 and beta‐arrestin 2 differentially direct the phosphorylation‐dependent and ‐independent internalization and desensitization of delta‐opioid receptor

Abstract

δ-opioid receptor (DOR) and its phosphorylation-deficient mutant S363A (DORS363A) underwent internalization and desensitization during the long-term activation by [D-Pen2,D-Pen5]enkephalin (DPDPE). Co-expression of dominant negative mutant of dynamin (DynK44E) blocked the internalization of both DOR and DORS363A without significant influence on their desensitization. Confocal microscopy studies using β-arrestinGFP indicated that both DOR and DORS363A activation could induce transient translocation of the β-arrestins to the plasma membrane. Internalization and desensitization of both DOR and its phosphorylation-deficient mutant DTS were blocked in mouse embryonic fibroblasts (MEF) cells lacking β-arrestin1 and β-arrestin 2 (β arr1−/−/β arr2−/−) upon long-term treatment of DPDPE, suggesting that β-arrestins is a key determinant in triggering receptor desensitization. Internalization of DOR was impaired similarly in MEF cells lacking β-arr1 (β arr1−/−) or cells lacking β-arr2 (β arr2−/−). However, desensitization of DOR in β arr1−/− cells was slightly reduced, while the desensitization of DOR was significantly impaired in β arr2−/− cells. On the other hand, both internalization and desensitization of DTS is not significantly impaired in both β arr1−/− and β arr2−/− cells. These results indicate that β-arrestin 1 and β-arrestin 2 are differentially required in the phosphorylation-dependent and -independent internalization and desensitization of DOR. (These studies are supported by NIDA grants DA007339, DA016674, DA000564, DA011806)