| First Author | Sato M | Year | 2012 |
| Journal | J Biol Chem | Volume | 287 |
| Issue | 24 | Pages | 20674-88 |
| PubMed ID | 22535965 | Mgi Jnum | J:186511 |
| Mgi Id | MGI:5432456 | Doi | 10.1074/jbc.M111.280651 |
| Citation | Sato M, et al. (2012) Interaction with caveolin-1 modulates G protein coupling of mouse beta3-adrenoceptor. J Biol Chem 287(24):20674-88 |
| abstractText | Caveolins act as scaffold proteins in multiprotein complexes and have been implicated in signaling by G protein-coupled receptors. Studies using knock-out mice suggest that beta(3)-adrenoceptor (beta(3)-AR) signaling is dependent on caveolin-1; however, it is not known whether caveolin-1 is associated with the beta(3)-AR or solely with downstream signaling proteins. We have addressed this question by examining the impact of membrane rafts and caveolin-1 on the differential signaling of mouse beta(3a)- and beta(3b)-AR isoforms that diverge at the distal C terminus. Only the beta(3b)-AR promotes pertussis toxin (PTX)-sensitive cAMP accumulation. When cells expressing the beta(3a)-AR were treated with filipin III to disrupt membrane rafts or transfected with caveolin-1 siRNA, the cyclic AMP response to the beta(3)-AR agonist CL316243 became PTX-sensitive, suggesting Galpha(i/o) coupling. The beta(3a)-AR C terminus, SP(384)PLNRF(389)DGY(392)EGARPF(398)PT, resembles a caveolin interaction motif. Mutant beta(3a)-ARs (F389A/Y392A/F398A or P384S/F389A) promoted PTX-sensitive cAMP responses, and in situ proximity assays demonstrated an association between caveolin-1 and the wild type beta(3a)-AR but not the mutant receptors. In membrane preparations, the beta(3b)-AR activated Galpha(o) and mediated PTX-sensitive cAMP responses, whereas the beta(3a)-AR did not activate Galpha(i/o) proteins. The endogenous beta(3a)-AR displayed Galpha(i/o) coupling in brown adipocytes from caveolin-1 knock-out mice or in wild type adipocytes treated with filipin III. Our studies indicate that interaction of the beta(3a)-AR with caveolin inhibits coupling to Galpha(i/o) proteins and suggest that signaling is modulated by a raft-enriched complex containing the beta(3a)-AR, caveolin-1, Galpha(s), and adenylyl cyclase. |
