| First Author | Armando I | Year | 2014 |
| Journal | FASEB J | Volume | 28 |
| Issue | 3 | Pages | 1422-34 |
| PubMed ID | 24308971 | Mgi Jnum | J:210701 |
| Mgi Id | MGI:5571679 | Doi | 10.1096/fj.13-243840 |
| Citation | Armando I, et al. (2014) Dopamine D3 receptor inhibits the ubiquitin-specific peptidase 48 to promote NHE3 degradation. FASEB J 28(3):1422-34 |
| abstractText | The dopamine D3 receptor (D3R) is crucial in the regulation of blood pressure and sodium balance, in that Drd3 gene ablation in mice results in hypertension and failure to excrete a dietary salt load. The mechanism responsible for the renal sodium retention in these mice is largely unknown. We now offer and describe a novel mechanism by which D3R decreases sodium transport in the long term by inhibiting the deubiquitinylating activity of ubiquitin-specific peptidase 48 (USP48), thereby promoting Na(+)-H(+) exchanger (NHE)-3 degradation. We found that stimulation with the D3R-specific agonist PD128907 (1 muM, 30 min) promoted the interaction and colocalization among D3R, NHE3, and USP48; inhibited USP48 activity (-35+/-6%, vs. vehicle), resulting in increased ubiquitinylated NHE3 (+140+/-10%); and decreased NHE3 expression (-50+/-9%) in human renal proximal tubule cells (hRPTCs). USP48 silencing decreased NHE3's half-life (USP48 siRNA t1/2=6.1 h vs. vehicle t1/2=12.9 h), whereas overexpression of USP48 increased NHE3 half-life (t1/2=21.8 h), indicating that USP48 protects NHE3 from degradation via deubiquitinylation. USP48 accounted for approximately 30% of the total deubiquitinylating activity in these cells. Extending our studies in vivo, we found that pharmacologic blockade of D3R via the D3R-specific antagonist GR103691 (1 mug/kg/min, 4 d) in C57Bl/6J mice increased renal NHE3 expression (+310+/-15%, vs. vehicle), whereas an innovative kidney-restricted Usp48 silencing via siRNA (3 mug/d, 7 d) increased ubiquitinylated NHE3 (+250+/-30%, vs. controls), decreased total NHE3 (-23+/-2%), and lowered blood pressure (-24+/-2 mm Hg), compared with that in control mice that received either the vehicle or nonsilencing siRNA. Our data demonstrate a crucial role for the dynamic interaction between D3R and USP48 in the regulation of NHE3 expression and function. |
