Abstract 12839: Expression and Functional Role of The Prorenin Receptor in Human Primary Aldosteronism
Hypothesis: The detection of prorenin in plasma of patients with Primary Aldosteronism (PA) suggests that prorenin plays a pathophysiologic role in PA by acting via the Pro-Renin Receptor (PRR). We therefore sought for the presence of the PRR in the normal human zona glomerulosa (ZG) and in aldosterone producing adenoma (APA), and investigated the functional response of PRR activation by prorenin on ERK1/2 phosphorylation in an adrenocortical cell line.
Methods and Results: Expression levels of PRR gene were 15- and 12-fold higher than those of the housekeeping gene PBGD in the normal human adrenal cortex (n=8) and in the APAs (n=11), respectively. Similar high expression levels were found in the the H295R and HAC15 cells. The PRR protein expression was confirmed by immunohistochemistry in the human and rat normal ZG, as well as in a pure population of APA cells obtained with an immunoseparation-based technique specifically targeted to the membrane CD56. Immunoblotting, confocal and immuno-gold electron microscopy localized PRR at the membrane level and also in mitochondria, nucleus, and Golgi’s vesicles.
Renin and prorenin (50 nM, both) activated ERK 1/2 phosphorylation in HAC15 cells (+287% and +374%, respectively, vs. unstimulated cells, control, p≤0.0001), at extent comparable to that induced by 100 nM Ang II (+328% vs control, p≤0.0001). Irbesartan (5 μM) abolished ERK 1/2 phosphorylation induced by renin or Ang II, but only in part prevented that induced by Prorenin, while Aliskiren (5 and 50 μM) was ineffective. Results were similar n H295R cells.
Conclusions: 1) The PRR is expressed in the ZG of the human and rat adrenal gland, as well as in APA and H295 and HAC15 cell lines. 2) the expression was found both in the cell membrane and in the intracellular organelles. 3) Prorenin (and renin) induced phosphorylation of ERK 1/2 in HAC15, with comparable effects to those exerted by Ang II. 4) Prorenin-, but not renin-mediated ERK 1/2 phosphorylation, was independent of Ang II generation and binding of AT1.
- © 2013 by American Heart Association, Inc.