Abstract P099: Angiotensin Type I Receptor (AT1R) and (Pro)renin Receptor (PRR) Functional Heterodimer Mediates ERK Phosphorylation
Receptor dimerization was shown to enhance the receptor efficacy, trafficking and signal transduction. Angiotensin II type 1 receptor (AT1R) and (Pro)renin receptor (PRR) are expressed in the kidney. Studies demonstrated that these two receptors have some similarities in their signaling mechanisms and effects. In the present study we hypothesized that the AT1R and PRR form functional heterodimer to enhance cellular ERK phosphorylation. Using Immunoprecipitation technique, confocal immunofluorescence staining (IF), and fluorescence resonance energy transfer (FRET), we evaluated the presence of AT1R and PRR heterodimer in rat renal mesangial (RMC) and PC12W cells transfected with AT1R. These two receptors coimmunoprecipitated at 80kD band. IF demonstrated AT1R and PRR co-localization as shown in figure below and FRET demonstrated the physical distance between them to be less than 10nm (<100 Å), providing strong evidence for these receptors heterodimerization. To evaluate the function of the AT1R/PRR dimer, PC12W cells were treated with scramble siRNA or PRR siRNA . There were no significant differences in phosphorylation of ERK between control and scramble siRNA. PRR siRNA treatment significantly reduced the ERK phosphorylation by 35%, P<0.05. There was 60% (P<0.01) increase in ERK phosphorylation in PC12W cells transfected with AT1R. In these cells, PRR siRNA treatment attenuated the increase in ERK phosphorylation by 33% (P< 0.05). We conclude that AT1R-PRR form a heterodimer that is functionally active to enhance ERK phosphorylation.
Author Disclosures: S. Quadri: None. C. Li: None. S. Culver: None. H.M. Siragy: None.
- © 2015 by American Heart Association, Inc.