RT Journal Article
SR Electronic
T1 Regulation of D1 Dopamine Receptor Trafficking and Signaling by Caveolin-1
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1157
OP 1170
DO 10.1124/mol.107.034769
VO 72
IS 5
A1 Michael M. C. Kong
A1 Ahmed Hasbi
A1 Michael Mattocks
A1 Theresa Fan
A1 Brian F. O'Dowd
A1 Susan R. George
YR 2007
UL http://molpharm.aspetjournals.org/content/72/5/1157.abstract
AB There is accumulating evidence that G protein-coupled receptor signaling is regulated by localization in lipid raft microdomains. In this report, we determined that the D1 dopamine receptor (D1R) is localized in caveolae, a subset of lipid rafts, by sucrose gradient fractionation and confocal microscopy. Through coimmunoprecipitation and bioluminescence resonance energy transfer assays, we demonstrated that this localization was mediated by an interaction between caveolin-1 and D1R in COS-7 cells and an isoform-selective interaction between D1R and caveolin-1α in rat brain. We determined that the D1R interaction with caveolin-1 required a putative caveolin binding motif identified in transmembrane domain 7. Agonist stimulation of D1R caused translocation of D1R into caveolin-1-enriched sucrose fractions, which was determined to be a result of D1R endocytosis through caveolae. This was found to be protein kinase A-independent and a kinetically slower process than clathrin-mediated endocytosis. Site-directed mutagenesis of the caveolin binding motif at amino acids Phe313 and Trp318 significantly attenuated caveolar endocytosis of D1R. We also found that these caveolin binding mutants had a diminished capacity to stimulate cAMP production, which was determined to be due to constitutive desensitization of these receptors. In contrast, we found that D1Rs had an enhanced ability to maximally generate cAMP in chemically induced caveolae-disrupted cells. Taken together, these data suggest that caveolae has an important role in regulating D1R turnover and signaling in brain. The American Society for Pharmacology and Experimental Therapeutics