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Ramkumar N, Stuart D, Mironova E, Bugay V, Wang S, Abraham N, Ichihara A, Stockand JD, Kohan DE. Renal tubular epithelial cell prorenin receptor regulates blood pressure and sodium transport. Am J Physiol Renal Physiol 2016; 311:F186-94. [PMID: 27053687 DOI: 10.1152/ajprenal.00088.2016] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 03/31/2016] [Indexed: 12/31/2022] Open
Abstract
The physiological significance of the renal tubular prorenin receptor (PRR) has been difficult to elucidate due to developmental abnormalities associated with global or renal-specific PRR knockout (KO). We recently developed an inducible renal tubule-wide PRR KO using the Pax8/LC1 transgenes and demonstrated that disruption of renal tubular PRR at 1 mo of age caused no renal histological abnormalities. Here, we examined the role of renal tubular PRR in blood pressure (BP) regulation and Na(+) excretion and investigated the signaling mechanisms by which PRR regulates Na(+) balance. No detectable differences in BP were observed between control and PRR KO mice fed normal- or low-Na(+) diets. However, compared with controls, PRR KO mice had elevated plasma renin concentration and lower cumulative Na(+) balance with normal- and low-Na(+) intake. PRR KO mice had an attenuated hypertensive response and reduced Na(+) retention following angiotensin II (ANG II) infusion. Furthermore, PRR KO mice had significantly lower epithelial Na(+) channel (ENaC-α) expression. Treatment with mouse prorenin increased, while PRR antagonism decreased, ENaC activity in isolated split-open collecting ducts (CD). The prorenin effect was prevented by protein kinase A and Akt inhibition, but unaffected by blockade of AT1, ERK1/2, or p38 MAPK pathways. Taken together, these data indicate that renal tubular PRR, likely via direct prorenin/renin stimulation of PKA/Akt-dependent pathways, stimulates CD ENaC activity. Absence of renal tubular PRR promotes Na(+) wasting and reduces the hypertensive response to ANG II.
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Affiliation(s)
- Nirupama Ramkumar
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah;
| | - Deborah Stuart
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Elena Mironova
- Department of Physiology, University of Texas Health Science Center, San Antonio, Texas; and
| | - Vladislav Bugay
- Department of Physiology, University of Texas Health Science Center, San Antonio, Texas; and
| | - Shuping Wang
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Nikita Abraham
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Atsuhiro Ichihara
- Department of Medicine II, Endocrinology and Hypertension, Tokyo Women's Medical University, Tokyo, Japan
| | - James D Stockand
- Department of Physiology, University of Texas Health Science Center, San Antonio, Texas; and
| | - Donald E Kohan
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah; Veterans Affairs Medical Center, Salt Lake City, Utah
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Trepiccione F, Gerber SD, Grahammer F, López-Cayuqueo KI, Baudrie V, Păunescu TG, Capen DE, Picard N, Alexander RT, Huber TB, Chambrey R, Brown D, Houillier P, Eladari D, Simons M. Renal Atp6ap2/(Pro)renin Receptor Is Required for Normal Vacuolar H+-ATPase Function but Not for the Renin-Angiotensin System. J Am Soc Nephrol 2016; 27:3320-3330. [PMID: 27044666 DOI: 10.1681/asn.2015080915] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 02/24/2016] [Indexed: 01/22/2023] Open
Abstract
ATPase H+-transporting lysosomal accessory protein 2 (Atp6ap2), also known as the (pro)renin receptor, is a type 1 transmembrane protein and an accessory subunit of the vacuolar H+-ATPase (V-ATPase) that may also function within the renin-angiotensin system. However, the contribution of Atp6ap2 to renin-angiotensin-dependent functions remains unconfirmed. Using mice with an inducible conditional deletion of Atp6ap2 in mouse renal epithelial cells, we found that decreased V-ATPase expression and activity in the intercalated cells of the collecting duct impaired acid-base regulation by the kidney. In addition, these mice suffered from marked polyuria resistant to desmopressin administration. Immunoblotting revealed downregulation of the medullary Na+-K+-2Cl- cotransporter NKCC2 in these mice compared with wild-type mice, an effect accompanied by a hypotonic medullary interstitium and impaired countercurrent multiplication. This phenotype correlated with strong autophagic defects in epithelial cells of medullary tubules. Notably, cells with high accumulation of the autophagosomal substrate p62 displayed the strongest reduction of NKCC2 expression. Finally, nephron-specific Atp6ap2 depletion did not affect angiotensin II production, angiotensin II-dependent BP regulation, or sodium handling in the kidney. Taken together, our results show that nephron-specific deletion of Atp6ap2 does not affect the renin-angiotensin system but causes a combination of renal concentration defects and distal renal tubular acidosis as a result of impaired V-ATPase activity.
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Affiliation(s)
- Francesco Trepiccione
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche_S970, Paris Centre de Recherche Cardiovasculaire, Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France.,Department of Cardio-Thoracic and Respiratory Science, Second University of Naples, Caserta, Italy
| | - Simon D Gerber
- Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, Paris, France
| | - Florian Grahammer
- Renal Division, University Medical Center Freiburg, Freiburg, Germany
| | - Karen I López-Cayuqueo
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche_S970, Paris Centre de Recherche Cardiovasculaire, Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France.,Centro de Estudios Científicos, Valdivia, Chile
| | - Véronique Baudrie
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche_S970, Paris Centre de Recherche Cardiovasculaire, Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
| | - Teodor G Păunescu
- Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts
| | - Diane E Capen
- Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts
| | - Nicolas Picard
- Centre National de la Recherche Scientifique Equipe de Recherche Labelisée 8228, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche_S1138, Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris, France
| | - R Todd Alexander
- Department of Pediatrics, University of Alberta, Edmonton, Canada; and
| | - Tobias B Huber
- Renal Division, University Medical Center Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University, Freiburg, Germany
| | - Regine Chambrey
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche_S970, Paris Centre de Recherche Cardiovasculaire, Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
| | - Dennis Brown
- Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts
| | - Pascal Houillier
- Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts
| | - Dominique Eladari
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche_S970, Paris Centre de Recherche Cardiovasculaire, Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France;
| | - Matias Simons
- Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, Paris, France;
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Soluble (pro)renin receptor via β-catenin enhances urine concentration capability as a target of liver X receptor. Proc Natl Acad Sci U S A 2016; 113:E1898-906. [PMID: 26984496 DOI: 10.1073/pnas.1602397113] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The extracellular domain of the (pro)renin receptor (PRR) is cleaved to produce a soluble (pro)renin receptor (sPRR) that is detected in biological fluid and elevated under certain pathological conditions. The present study was performed to define the antidiuretic action of sPRR and its potential interaction with liver X receptors (LXRs), which are known regulators of urine-concentrating capability. Water deprivation consistently elevated urinary sPRR excretion in mice and humans. A template-based algorithm for protein-protein interaction predicted the interaction between sPRR and frizzled-8 (FZD8), which subsequently was confirmed by coimmunoprecipitation. A recombinant histidine-tagged sPRR (sPRR-His) in the nanomolar range induced a remarkable increase in the abundance of renal aquaporin 2 (AQP2) protein in primary rat inner medullary collecting duct cells. The AQP2 up-regulation relied on sequential activation of FZD8-dependent β-catenin signaling and cAMP-PKA pathways. Inhibition of FZD8 or tankyrase in rats induced polyuria, polydipsia, and hyperosmotic urine. Administration of sPRR-His alleviated the symptoms of diabetes insipidus induced in mice by vasopressin 2 receptor antagonism. Administration of the LXR agonist TO901317 to C57/BL6 mice induced polyuria and suppressed renal AQP2 expression associated with reduced renal PRR expression and urinary sPRR excretion. Administration of sPRR-His reversed most of the effects of TO901317. In cultured collecting duct cells, TO901317 suppressed PRR protein expression, sPRR release, and PRR transcriptional activity. Overall we demonstrate, for the first time to our knowledge, that sPRR exerts antidiuretic action via FZD8-dependent stimulation of AQP2 expression and that inhibition of this pathway contributes to the pathogenesis of diabetes insipidus induced by LXR agonism.
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