Collecting duct principal, but not intercalated, cell prorenin receptor regulates renal sodium and water excretion

The collecting duct is the predominant nephron site of prorenin and prorenin receptor (PRR) expression. We previously demonstrated that the collecting duct PRR regulates epithelial Na+ channel (ENaC) activity and water transport; however, which cell type is involved remains unclear. Herein, we examined the effects of principal cell (PC) or intercalated cell (IC) PRR deletion on renal Na+ and water handling. PC or IC PRR knockout (KO) mice were obtained by crossing floxed PRR mice with mice harboring Cre recombinase under the control of the AQP2 or B1 subunit of the H+ ATPase promoters, respectively. PC KO mice had reduced renal medullary ENaC-α abundance and increased urinary Na+ losses on a low-Na+ diet compared with controls. Conversely, IC KO mice had no apparent differences in Na+ balance or ENaC abundance compared with controls. Acute treatment with prorenin increased ENaC channel number and open probability in acutely isolated cortical collecting ducts from control and IC PRR KO, but not PC PRR KO, mice. Furthermore, compared with controls, PC KO, but not IC KO mice, had increased urine volume, reduced urine osmolality, and reduced abundance of renal medullary AQP2. Taken together, these findings indicate that PC, but not IC, PRR modulates ENaC activity, urinary Na+ excretion, and water transport.

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Nephron-specific deletion of the prorenin receptor causes a urine concentration defect

AJP Renal Physiology ◽

10.1152/ajprenal.00126.2015 ◽

2015 ◽

Vol 309 (1) ◽

pp. F48-F56 ◽

Cited By ~ 36

Author(s):

Nirupama Ramkumar ◽

Deborah Stuart ◽

Matias Calquin ◽

Syed Quadri ◽

Shuping Wang ◽

...

Keyword(s):

Water Intake ◽

Gene Knockout ◽

Collecting Duct ◽

Urine Volume ◽

Plasma Osmolality ◽

Renin Angiotensin System ◽

Urine Osmolality ◽

Water Restriction ◽

Water Excretion ◽

Prorenin Receptor

The prorenin receptor (PRR), a recently discovered component of the renin-angiotensin system, is expressed in the nephron in general and the collecting duct in particular. However, the physiological significance of nephron PRR remains unclear, partly due to developmental abnormalities associated with global or renal-specific PRR gene knockout (KO). Therefore, we developed mice with inducible nephron-wide PRR deletion using Pax8-reverse tetracycline transactivator and LC-1 transgenes and loxP flanked PRR alleles such that ablation of PRR occurs in adulthood, after induction with doxycycline. Nephron-specific PRR KO mice have normal survival to ∼1 yr of age and no renal histological defects. Compared with control mice, PRR KO mice had 65% lower medullary PRR mRNA and protein levels and markedly diminished renal PRR immunofluorescence. During both normal water intake and mild water restriction, PRR KO mice had significantly lower urine osmolality, higher water intake, and higher urine volume compared with control mice. No differences were seen in urine vasopressin excretion, urine Na+ and K+ excretion, plasma Na+, or plasma osmolality between the two groups. However, PRR KO mice had reduced medullary aquaporin-2 levels and arginine vasopressin-stimulated cAMP accumulation in the isolated renal medulla compared with control mice. Taken together, these results suggest nephron PRR can potentially modulate renal water excretion.

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Collecting duct-specific knockout of adenylyl cyclase type VI causes a urinary concentration defect in mice

AJP Renal Physiology ◽

10.1152/ajprenal.00397.2011 ◽

2012 ◽

Vol 302 (1) ◽

pp. F78-F84 ◽

Cited By ~ 42

Author(s):

Karl P. Roos ◽

Kevin A. Strait ◽

Kalani L. Raphael ◽

Mitsi A. Blount ◽

Donald E. Kohan

Keyword(s):

Adenylyl Cyclase ◽

Water Intake ◽

Arginine Vasopressin ◽

Water Deprivation ◽

Collecting Duct ◽

Urine Volume ◽

Urine Osmolality ◽

Camp Accumulation ◽

Water Excretion ◽

Normal Water

Collecting duct (CD) adenylyl cyclase VI (AC6) has been implicated in arginine vasopressin (AVP)-stimulated renal water reabsorption. To evaluate the role of CD-derived AC6 in regulating water homeostasis, mice were generated with CD-specific knockout (KO) of AC6 using the Cre/loxP system. CD AC6 KO and controls were studied under normal water intake, chronically water loaded, or water deprived; all of these conditions were repeated in the presence of continuous administration of 1-desamino-8-d-arginine vasopressin (DDAVP). During normal water intake or after water deprivation, urine osmolality (Uosm) was reduced in CD AC6 KO animals vs. controls. Similarly, Uosm was decreased in CD AC6 KO mice vs. controls after water deprivation+DDAVP administration. Pair-fed (with controls) CD AC6 KO mice also had lower urine osmolality vs. controls. There were no detectable differences between KO and control animals in fluid intake or urine volume under any conditions. CD AC6 KO mice did not have altered plasma AVP levels vs. controls. AVP-stimulated cAMP accumulation was reduced in acutely isolated inner medullary CD (IMCD) from CD A6 KO vs. controls. Medullary aquaporin-2 (AQP2) protein expression was lower in CD AC6 KO mice vs. controls. There were no differences in urinary urea excretion or IMCD UT-A1 expression; however, IMCD UT-A3 expression was reduced in CD AC6 KO mice vs. controls. In summary, AC6 in the CD regulates renal water excretion, most likely through control of AVP-stimulated cAMP accumulation and AQP2.

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Collecting duct-specific knockout of nitric oxide synthase 3 impairs water excretion in a sex-dependent manner

AJP Renal Physiology ◽

10.1152/ajprenal.00494.2016 ◽

2016 ◽

Vol 311 (5) ◽

pp. F1074-F1083 ◽

Cited By ~ 8

Author(s):

Yang Gao ◽

Deborah Stuart ◽

Jennifer S. Pollock ◽

Takamune Takahishi ◽

Donald E. Kohan

Keyword(s):

Nitric Oxide ◽

Blood Pressure ◽

Collecting Duct ◽

Urine Volume ◽

Plasma Renin ◽

Urine Osmolality ◽

Dependent Manner ◽

Water Reabsorption ◽

Water Excretion ◽

Water Loading

Nitric oxide (NO) inhibits collecting duct (CD) Na+ and water reabsorption. Mice with CD-specific knockout (KO) of NO synthase 1 (NOS1) have salt-sensitive hypertension. In contrast, the role of NOS3 in CD salt and water reabsorption is unknown. Mice with CD NOS3 KO were generated with loxP-flanked exons 9–12 (encodes the calmodulin binding site) of the NOS3 gene and the aquaporin-2 promoter-Cre transgene. There were no differences between control and CD NOS3 KO mice, irrespective of sex, in food intake, water intake, urine volume, urinary Na+ or K+ excretion, plasma renin concentration, blood pressure, or pulse during 7 days of normal (0.3%), high (3.17%), or low (0.03%) Na+ intake. Blood pressure was similar between genotypes during DOCA-high salt. CD NOS3 KO did not alter urine volume or urine osmolality after water deprivation. In contrast, CD NOS3 KO male, but not female, mice had lower urine volume and higher urine osmolality over the course of 7 days of water loading compared with control mice. Male, but not female, CD NOS3 KO mice had reduced urinary nitrite+nitrate excretion compared with controls after 7 days of water loading. Urine AVP and AVP-stimulated cAMP accumulation in isolated inner medullary CD were similar between genotypes. Western analysis did not reveal a significant effect of CD NOS3 KO on renal aquaporin expression. In summary, these data suggest that CD NOS3 may be involved in the diuretic response to a water load in a sex-specific manner; the mechanism of this effect remains to be determined.

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Downregulation of renal vasopressin V2 receptor and aquaporin-2 expression parallels age-associated defects in urine concentration

AJP Renal Physiology ◽

10.1152/ajprenal.00403.2003 ◽

2004 ◽

Vol 287 (4) ◽

pp. F797-F805 ◽

Cited By ~ 37

Author(s):

Ying Tian ◽

Ryota Serino ◽

Joseph G. Verbalis

Keyword(s):

Collecting Duct ◽

Water Channel ◽

Age Groups ◽

Urine Osmolality ◽

Brown Norway ◽

Water Restriction ◽

Water Excretion ◽

F1 Hybrid ◽

Young Rats ◽

Aquaporin 2

Renal concentrating ability is known to be impaired with aging. The antidiuretic hormone AVP plays an important role in renal water excretion by regulating the membrane insertion and abundance of the water channel aquaporin-2 (AQP2); this effect is primarily mediated via the V2 subtype of the AVP receptor (V2R). This study evaluated the hypothesis that decreased renal sensitivity to AVP, with subsequent altered renal AQP2 expression, contributes to the reduced urinary concentrating ability with aging. Our results show that under baseline conditions, urine osmolality is significantly lower in aged Fischer 344 and Brown-Norway F1 hybrid (F344BN) rats despite equivalent plasma AVP concentrations as in young rats. Levels of kidney V2R mRNA expression and AQP2 abundances were also significantly decreased in aged F344BN rats, as was AQP2 immunostaining in collecting duct cells. In response to moderate water restriction, urine osmolality increased by significantly lesser amounts in aged F344BN rats compared with young rats despite similar increases in plasma AVP levels. Moderate water restriction induced equivalent relative increases in renal AQP2 abundances in all age groups but resulted in significantly lower abundances in total kidney AQP2 protein in aged compared with young F344BN rats. These results therefore demonstrate a functional impairment of renal concentrating ability in aged F344BN rats that is not due to impaired secretion of AVP but rather appears to be related to impaired responsiveness of the kidney to AVP that is secondary, at least in part, to a downregulation of renal V2R expression and AQP2 abundance.

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Abstract 021: Nephron Specific Deletion of the Prorenin Receptor Modulates Blood Pressure and Urinary Na+ Excretion

Hypertension ◽

10.1161/hyp.66.suppl_1.021 ◽

2015 ◽

Vol 66 (suppl_1) ◽

Author(s):

Nirupama Ramkumar ◽

Deborah Stuart ◽

Elena V Mironova ◽

Vladislav Bugay ◽

Mykola Mamenko ◽

...

Keyword(s):

Blood Pressure ◽

Structural Defects ◽

Ang Ii ◽

Open Probability ◽

Protein Levels ◽

Prorenin Receptor ◽

Collecting Ducts ◽

Dependent Pathway ◽

Early Lethality ◽

Specific Deletion

The nephron prorenin receptor (PRR) may modulate blood pressure (BP) and Na+ balance. Since previous models of PRR knockout (KO) mice had early lethality and/or structural defects, we developed an inducible nephron-wide PRR KO using the Pax8/LC1 transgenes. Disruption of nephron PRR at 1 month of age caused no renal histological abnormalities. On a normal Na+ diet, wild-type (WT) and PRR KO mice had similar BP and Na+ excretion. However, PRR KO mice had elevated PRC (KO- 377 ± 77 vs WT- 127 ± 19 ng Ang-I/ml/hr) and a 50% decrease in renal ENaC-α protein. Protein levels of NHE3, NKCC2, NCC and ENaC-β/γ were similar between the two groups. Treatment with mouse prorenin (10 nM for 30 min) increased ENaC channel number by 2-fold, but not open probability, in isolated split-open cortical collecting ducts (CCD) from WT mice; this was prevented by Akt inhibition (A6730) but unaffected by blockade of AT-1 (losartan), ERK1/2 (U0126) or p38 MAPK (SB203580). Addition of prorenin (10 nM) did not change isolated CCD [Ca2+]i as assessed by Fura-2 loading (10 min exposure with readings every 3 sec). On a low Na+ diet, PRR KO mice had increased Na+ excretion (Day 2: KO - 66 ± 11 vs WT- 42 ± 6 μmol/day; Day 6: KO - 39 ± 4 vs ET- 23 ± 4 μmol/day) however, no differences in BP were observed. PRC was elevated in PRR KO mice on a low Na+ diet (KO- 384 ± 40 vs WT-174 ± 12 ng/ Ang-I/ml/hr). PRR KO mice had an attenuated hypertensive response to Angiotensin-II (Ang-II) infusion at 600 ng/Kg/min for 2 weeks (MAP: KO - 117 ± 4 vs WT - 133 ± 4 mm Hg over the course of Ang-II infusion). Urinary Na+ excretion was elevated in Ang-II treated PRR KO mice as compared to WT mice (KO-344 ± 14 vs WT-268 ±30 μmol/day). Taken together, these data indicate that nephron PRR, likely via direct prorenin/renin stimulation of an Akt-dependent pathway, stimulates CCD ENaC activity. Absence of nephron PRR promotes Na+ wasting and reduces the hypertensive response to Ang-II.

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Collecting duct prorenin receptor knockout reduces renal function, increases sodium excretion, and mitigates renal responses in ANG II-induced hypertensive mice

AJP Renal Physiology ◽

10.1152/ajprenal.00152.2017 ◽

2017 ◽

Vol 313 (6) ◽

pp. F1243-F1253 ◽

Cited By ~ 21

Author(s):

Minolfa C. Prieto ◽

Virginia Reverte ◽

Mykola Mamenko ◽

Marta Kuczeriszka ◽

Luciana C. Veiras ◽

...

Keyword(s):

Renal Function ◽

Collecting Duct ◽

Ang Ii ◽

Open Probability ◽

Sodium Transporters ◽

Prorenin Receptor ◽

Active Channels ◽

The Impact ◽

Renal Responses ◽

Stimulation Of

Augmented intratubular angiotensin (ANG) II is a key determinant of enhanced distal Na+ reabsorption via activation of epithelial Na+ channels (ENaC) and other transporters, which leads to the development of high blood pressure (BP). In ANG II-induced hypertension, there is increased expression of the prorenin receptor (PRR) in the collecting duct (CD), which has been implicated in the stimulation of the sodium transporters and resultant hypertension. The impact of PRR deletion along the nephron on BP regulation and Na+ handling remains controversial. In the present study, we investigate the role of PRR in the regulation of renal function and BP by using a mouse model with specific deletion of PRR in the CD (CDPRR-KO). At basal conditions, CDPRR-KO mice had decreased renal function and lower systolic BP associated with higher fractional Na+ excretion and lower ANG II levels in urine. After 14 days of ANG II infusion (400 ng·kg−1·min−1), the increases in systolic BP and diastolic BP were mitigated in CDPRR-KO mice. CDPRR-KO mice had lower abundance of cleaved αENaC and γENaC, as well as lower ANG II and renin content in urine compared with wild-type mice. In isolated CD from CDPRR-KO mice, patch-clamp studies demonstrated that ANG II-dependent stimulation of ENaC activity was reduced because of fewer active channels and lower open probability. These data indicate that CD PRR contributes to renal function and BP responses during chronic ANG II infusion by enhancing renin activity, increasing ANG II, and activating ENaC in the distal nephron segments.

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Deletion of the serine protease CAP2/Tmprss4 leads to dysregulated renal water handling upon dietary potassium depletion

Scientific Reports ◽

10.1038/s41598-019-55995-x ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Anna Keppner ◽

Darko Maric ◽

Chloé Sergi ◽

Camille Ansermet ◽

Damien De Bellis ◽

...

Keyword(s):

Serine Protease ◽

Knockout Mice ◽

Collecting Duct ◽

Urine Osmolality ◽

Transitional Epithelium ◽

Hormonal Changes ◽

Cortical Collecting Duct ◽

Deficient Diet ◽

Protein Levels ◽

Water Handling

AbstractThe kidney needs to adapt daily to variable dietary K+ contents via various mechanisms including diuretic, acid-base and hormonal changes that are still not fully understood. In this study, we demonstrate that following a K+-deficient diet in wildtype mice, the serine protease CAP2/Tmprss4 is upregulated in connecting tubule and cortical collecting duct and also localizes to the medulla and transitional epithelium of the papilla and minor calyx. Male CAP2/Tmprss4 knockout mice display altered water handling and urine osmolality, enhanced vasopressin response leading to upregulated adenylate cyclase 6 expression and cAMP overproduction, and subsequently greater aquaporin 2 (AQP2) and Na+-K+-2Cl− cotransporter 2 (NKCC2) expression following K+-deficient diet. Urinary acidification coincides with significantly increased H+,K+-ATPase type 2 (HKA2) mRNA and protein expression, and decreased calcium and phosphate excretion. This is accompanied by increased glucocorticoid receptor (GR) protein levels and reduced 11β-hydroxysteroid dehydrogenase 2 activity in knockout mice. Strikingly, genetic nephron-specific deletion of GR leads to the mirrored phenotype of CAP2/Tmprss4 knockouts, including increased water intake and urine output, urinary alkalinisation, downregulation of HKA2, AQP2 and NKCC2. Collectively, our data unveil a novel role of the serine protease CAP2/Tmprss4 and GR on renal water handling upon dietary K+ depletion.

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Cisplatin nephrotoxicity in rats: defect in papillary hypertonicity

AJP Renal Physiology ◽

10.1152/ajprenal.1981.241.2.f175 ◽

1981 ◽

Vol 241 (2) ◽

pp. F175-F185 ◽

Cited By ~ 10

Author(s):

R. Safirstein ◽

P. Miller ◽

S. Dikman ◽

N. Lyman ◽

C. Shapiro

Keyword(s):

Glomerular Filtration Rate ◽

Proximal Tubule ◽

Glomerular Filtration ◽

Filtration Rate ◽

Collecting Duct ◽

Urine Volume ◽

Distal Tubule ◽

Urine Osmolality ◽

Solute Content ◽

Cisplatin Nephrotoxicity

We examined the effects of cisplatin (5 mg/kg BW) on renal function in rats. Three days after administration of cisplatin whole kidney clearance of inulin fell and 24-h urine volume increased. Maximal urine osmolality and papillary solute content were reduced. Superficial nephron glomerular filtration rate measured along the proximal tubule, where no leak of inulin could be demonstrated, was reduced in cisplatin-treated animals. Differences between superficial nephron glomerular filtration rate determined in proximal and distal tubules were greater in cisplatin-treated rats than in control rats. Neither a change in fluid or sodium movement along superficial nephrons nor a reduced early distal tubule transepithelial sodium gradient explain the polyuria. Urea was reabsorbed from, not added to, the loop fluid in cisplatin-treated animals. Morphologic changes were evident in the S3 segment of the proximal tubule in cisplatin-treated animals but the glomeruli were normal. Polyuria occurred despite diminished glomerular filtration rate in cisplatin nephrotoxicity. The diminished concentration of salt and urea in the papilla as a result of abnormal function of the collecting duct or pars recta portion of the proximal tubule contributed to the defect in concentrating ability.

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Lectin-gold cytochemistry reveals intercalated cell heterogeneity along rat kidney collecting ducts

AJP Cell Physiology ◽

10.1152/ajpcell.1985.248.3.c348 ◽

1985 ◽

Vol 248 (3) ◽

pp. C348-C356 ◽

Cited By ~ 41

Author(s):

D. Brown ◽

J. Roth ◽

L. Orci

Keyword(s):

Plasma Membranes ◽

Collecting Duct ◽

Rat Kidney ◽

Lectin Binding ◽

Helix Pomatia ◽

Intercalated Cells ◽

Double Labeling ◽

Thin Sections ◽

Intercalated Cell ◽

Collecting Ducts

The lectin-gold technique was used to detect Helix pomatia and Dolichos biflorus lectin binding sites directly on semithin and thin sections of rat kidney collecting ducts. Intercalated cell apical plasma membranes and the membranes of apical cytoplasmic vesicles were heavily labeled in the cortex and outer stripe of the outer medulla but were negative or very weakly labeled in the inner stripe and inner medulla. In contrast, clear cell apical membranes were labeled along the entire length of the collecting duct. Double labeling of semithin cryostat sections with a specific antibody and lectin-gold complexes was used to demonstrate that the intercalated cells in all regions studied contained carbonic anhydrase, even though the lectin binding differed. These results indicate that, in terms of their glycocalyx composition, intercalated cells represent a heterogeneous population in different regions of the collecting duct.

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Upregulation of collecting duct aquaporin-2 by metabolic acidosis: role of vasopressin

AJP Cell Physiology ◽

10.1152/ajpcell.00394.2003 ◽

2004 ◽

Vol 286 (5) ◽

pp. C1019-C1030 ◽

Cited By ~ 33

Author(s):

Hassane Amlal ◽

Sulaiman Sheriff ◽

Manoocher Soleimani

Keyword(s):

Metabolic Acidosis ◽

Mrna Expression ◽

Collecting Duct ◽

Urine Volume ◽

Urine Osmolality ◽

Northern Hybridization ◽

Water Control ◽

Expression Levels ◽

Aquaporin 2 ◽

Mrna Expression Levels

Metabolic acidosis is associated with alteration in fluid and electrolyte reabsorption in a number of nephron segments. However, the effects of metabolic acidosis on urine osmolality and aquaporin-2 (AQP-2) remain poorly understood. In these studies, we examined the effects of chronic metabolic acidosis on water handling by the kidney. Rats were placed in metabolic cages and subjected to water (control) or 280 mM NH4Cl loading for 120 h to induce metabolic acidosis. The results indicated a significant increase in urine osmolality with no change in urine volume or urinary Na+ excretion in acid-loaded animals. This effect was independent of alteration in fluid intake or salt/Cl- loading. Immunoblotting and Northern hybridization studies indicated that AQP-2 protein abundance and mRNA expression levels increased significantly along the collecting duct system of NH4Cl-but not NaCl-loaded animals. RIA results indicated that metabolic acidosis was associated with a fourfold increase in circulating levels of vasopressin (AVP) and a significant increase in brain AVP mRNA expression levels. In conclusion, metabolic acidosis upregulates the expression levels of AQP-2 and increases urine osmolality, suggesting an adaptive increase in water reabsorption in the collecting duct. A concomitant increase in AVP synthesis and secretion likely plays an essential role in the adaptation of AQP-2 in metabolic acidosis.

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