Cytoplasmic tail of D1 dopaminergic receptor differentially regulates desensitization and phosphorylation by G protein-coupled receptor kinase 2 and 3 |
| |
Authors: | Keyvan SedaghatMario Tiberi |
| |
Affiliation: | Ottawa Hospital Research Institute, Neuroscience Program and Departments of Medicine/Cellular and Molecular Medicine/Psychiatry, University of Ottawa, Ottawa, ON, Canada |
| |
Abstract: | Herein, we investigate the differential D1 dopaminergic receptor (D1R) regulation by G protein-coupled receptor kinase (GRK) 2 and 3 using two truncated receptors lacking the distal (Δ425) and distal-central (Δ379) cytoplasmic tail (CT) regions. We first show the association between D1R and GRKs in co-transfected cells and rat striatum. Our studies further indicate that deletion of distal CT region of D1R does not alter the association between receptor and GRK2. Meanwhile, removal of both distal and central CT regions culminates in a drastic increase in the basal association between Δ379 and GRK2 relative to D1R and Δ425. Interestingly, CT truncations have no effect on the basal and DA-induced association of receptors with GRK3. Furthermore, we demonstrate that desensitization of D1R is considerably more robust in cells expressing GRK3. Notably, the robust GRK3-induced D1R desensitization is not attenuated by CT deletions. However, GRK2-induced Δ425 desensitization is not detectable whereas we unexpectedly find that Δ379 desensitization is similar to GRK2-induced D1R desensitization. GRK2 and GRK3-dependent desensitization of wild type D1R is not linked to differences in the extent of DA-induced receptor phosphorylation. Moreover, our studies show that GRK2-induced D1R phosphorylation is only modulated by deletion of distal CT region while distal and central CT regions control GRK3-induced D1R phosphorylation. Intriguingly, dopamine-induced Δ379 phosphorylation by GRK3 was significantly lower than receptor phosphorylation in cells harboring Δ379 alone or Δ379 and GRK2. Overall, our study suggests an intricate interplay between CT regions of D1R in differentially regulating receptor responsiveness by GRK2 and GRK3. |
| |
Keywords: | 7TM, seven-transmembrane AC, adenylyl cyclase Bmax, maximal binding capacity BSA, bovine serum albumin β2-AR, β2-adrenergic receptor CHO, Chinese Hamster Ovary CT, cytoplasmic tail D1R, dopamine D1 receptor D2R, dopamine D2 receptor DA, dopamine DMEM, Dulbecco's modified Eagle's medium DSP, dithiobis [succinimidylpropionate] FBS, fetal bovine serum GPCR, G protein-coupled receptor GRK, G protein-coupled receptor kinase HA, hemaglutinin HEK293, human embryonic kidney 293 IB, immunoblotting IP, immunoprecipitation MEM, minimum essential medium PBS, phosphate-buffered saline RIPA, radioimmunoprepitation assay SDS, sodium dodecyl sulfate WT, wild type |
本文献已被 ScienceDirect 等数据库收录! |
|