scholarly journals Two Mineralocorticoid Receptor–Mediated Mechanisms of Pendrin Activation in Distal Nephrons

2020 ◽  
Vol 31 (4) ◽  
pp. 748-764 ◽  
Author(s):  
Nobuhiro Ayuzawa ◽  
Mitsuhiro Nishimoto ◽  
Kohei Ueda ◽  
Daigoro Hirohama ◽  
Wakako Kawarazaki ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Angiotensin Ii ◽  
Knockout Mice ◽  
Mineralocorticoid Receptor ◽  
Receptor Activation ◽  
Intercalated Cells ◽  
Renin Angiotensin Aldosterone System ◽  
Salt Diet ◽  
Principal Cells ◽  
Salt Sensitive Hypertension

BackgroundRegulation of sodium chloride transport in the aldosterone-sensitive distal nephron is essential for fluid homeostasis and BP control. The chloride-bicarbonate exchanger pendrin in β-intercalated cells, along with sodium chloride cotransporter (NCC) in distal convoluted tubules, complementarily regulate sodium chloride handling, which is controlled by the renin-angiotensin-aldosterone system.MethodsUsing mice with mineralocorticoid receptor deletion in intercalated cells, we examined the mechanism and roles of pendrin upregulation via mineralocorticoid receptor in two different models of renin-angiotensin-aldosterone system activation. We also used aldosterone-treated NCC knockout mice to examine the role of pendrin regulation in salt-sensitive hypertension.ResultsDeletion of mineralocorticoid receptor in intercalated cells suppressed the increase in renal pendrin expression induced by either exogenous angiotensin II infusion or endogenous angiotensin II upregulation via salt restriction. When fed a low-salt diet, intercalated cell–specific mineralocorticoid receptor knockout mice with suppression of pendrin upregulation showed BP reduction that was attenuated by compensatory activation of NCC. In contrast, upregulation of pendrin induced by aldosterone excess combined with a high-salt diet was scarcely affected by deletion of mineralocorticoid receptor in intercalated cells, but depended instead on hypokalemic alkalosis through the activated mineralocorticoid receptor–epithelial sodium channel cascade in principal cells. In aldosterone-treated NCC knockout mice showing upregulation of pendrin, potassium supplementation corrected alkalosis and inhibited the pendrin upregulation, thereby lowering BP.ConclusionsIn conjunction with NCC, the two pathways of pendrin upregulation, induced by angiotensin II through mineralocorticoid receptor activation in intercalated cells and by alkalosis through mineralocorticoid receptor activation in principal cells, play important roles in fluid homeostasis during salt depletion and salt-sensitive hypertension mediated by aldosterone excess.

scholarly journals Aldosterone Is Essential for Angiotensin II-Induced Upregulation of Pendrin

2017 ◽  
Vol 29 (1) ◽  
pp. 57-68 ◽  
Author(s):  
Daigoro Hirohama ◽  
Nobuhiro Ayuzawa ◽  
Kohei Ueda ◽  
Mitsuhiro Nishimoto ◽  
Wakako Kawarazaki ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Mineralocorticoid Receptor ◽  
Intercalated Cells ◽  
Wild Type ◽  
Dietary Salt ◽  
Renin Angiotensin Aldosterone System ◽  
Salt Restriction ◽  
Salt Diet ◽  
Low Salt ◽  
Dietary Salt Restriction

The renin-angiotensin-aldosterone system has an important role in the control of fluid homeostasis and BP during volume depletion. Dietary salt restriction elevates circulating angiotensin II (AngII) and aldosterone levels, increasing levels of the Cl−/HCO3− exchanger pendrin in β-intercalated cells and the Na+-Cl− cotransporter (NCC) in distal convoluted tubules. However, the independent roles of AngII and aldosterone in regulating these levels remain unclear. In C57BL/6J mice receiving a low-salt diet or AngII infusion, we evaluated the membrane protein abundance of pendrin and NCC; assessed the phosphorylation of the mineralocorticoid receptor, which selectively inhibits aldosterone binding in intercalated cells; and measured BP by radiotelemetry in pendrin-knockout and wild-type mice. A low-salt diet or AngII infusion upregulated NCC and pendrin levels, decreased the phosphorylation of mineralocorticoid receptor in β-intercalated cells, and increased plasma aldosterone levels. Notably, a low-salt diet did not alter BP in wild-type mice, but significantly decreased BP in pendrin-knockout mice. To dissect the roles of AngII and aldosterone, we performed adrenalectomies in mice to remove aldosterone from the circulation. In adrenalectomized mice, AngII infusion again upregulated NCC expression, but did not affect pendrin expression despite the decreased phosphorylation of mineralocorticoid receptor. By contrast, AngII and aldosterone coadministration markedly elevated pendrin levels in adrenalectomized mice. Our results indicate that aldosterone is necessary for AngII-induced pendrin upregulation, and suggest that pendrin contributes to the maintenance of normal BP in cooperation with NCC during activation of the renin-angiotensin-aldosterone system by dietary salt restriction.

scholarly journals PKCδ Mediates Mineralocorticoid Receptor Activation by Angiotensin II to Modulate Smooth Muscle Cell Function

Endocrinology ◽  
2019 ◽  
Vol 160 (9) ◽  
pp. 2101-2114 ◽  
Author(s):  
Qing Lu ◽  
Ana P Davel ◽  
Adam P McGraw ◽  
Sitara P Rao ◽  
Brenna G Newfell ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Mineralocorticoid Receptor ◽  
Target Gene ◽  
Cell Function ◽  
Receptor Activation ◽  
Serine Phosphorylation ◽  
Dependent Manner ◽  
Responsive Element ◽  
The Impact

Abstract Angiotensin II (AngII) and the mineralocorticoid receptor (MR) ligand aldosterone both contribute to cardiovascular disorders, including hypertension and adverse vascular remodeling. We previously demonstrated that AngII activates MR-mediated gene transcription in human vascular smooth muscle cells (SMCs), yet the mechanism and the impact on SMC function are unknown. Using an MR-responsive element-driven transcriptional reporter assay, we confirm that AngII induces MR transcriptional activity in vascular SMCs and endothelial cells, but not in Cos1 or human embryonic kidney-293 cells. AngII activation of MR was blocked by the MR antagonist spironolactone or eplerenone and the protein kinase C-δ (PKCδ) inhibitor rottlerin, implicating both in the mechanism. Similarly, small interfering RNA knockdown of PKCδ in SMCs prevented AngII-mediated MR activation, whereas knocking down of MR blocked both aldosterone- and AngII-induced MR function. Coimmunoprecipitation studies reveal that endogenous MR and PKCδ form a complex in SMCs that is enhanced by AngII treatment in association with increased serine phosphorylation of the MR N terminus. AngII increased mRNA expression of the SMC-MR target gene, FKBP51, via an MR-responsive element in intron 5 of the FKBP51 gene. The impact of AngII on FKBP51 reporter activity and gene expression in SMCs was inhibited by spironolactone and rottlerin. Finally, the AngII-induced increase in SMC number was also blocked by the MR antagonist spironolactone and the PKCδ inhibitor rottlerin. These data demonstrate that AngII activates MR transcriptional regulatory activity, target gene regulation, and SMC proliferation in a PKCδ-dependent manner. This new mechanism may contribute to synergy between MR and AngII in driving SMC dysfunction and to the cardiovascular benefits of MR and AngII receptor blockade in humans.

scholarly journals Mineralocorticoid receptor antagonism improves parenchymal arteriole dilation via a TRPV4-dependent mechanism and prevents cognitive dysfunction in hypertension

2018 ◽  
Vol 315 (5) ◽  
pp. H1304-H1315 ◽  
Author(s):  
Janice M. Diaz-Otero ◽  
Ting-Chieh Yen ◽  
Courtney Fisher ◽  
Daniel Bota ◽  
William F. Jackson ◽  
...  
Keyword(s):  
Cognitive Function ◽  
Angiotensin Ii ◽  
Mineralocorticoid Receptor ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Receptor Activation ◽  
Myogenic Tone ◽  
Transient Receptor Potential Vanilloid ◽  
Cerebrovascular Function ◽  
Transient Receptor

Hypertension and mineralocorticoid receptor activation cause cerebral parenchymal arteriole remodeling; this can limit cerebral perfusion and contribute to cognitive dysfunction. We used a mouse model of angiotensin II-induced hypertension to test the hypothesis that mineralocorticoid receptor activation impairs both transient receptor potential vanilloid (TRPV)4-mediated dilation of cerebral parenchymal arterioles and cognitive function. Mice (16−18 wk old, male, C57Bl/6) were treated with angiotensin II (800 ng·kg−1·min−1) with or without the mineralocorticoid receptor antagonist eplerenone (100 mg·kg−1·day−1) for 4 wk; sham mice served as controls. Data are presented as means ± SE; n = 5–14 mice/group. Eplerenone prevented the increased parenchymal arteriole myogenic tone and impaired carbachol-induced (10−9–10−5 mol/l) dilation observed during hypertension. The carbachol-induced dilation was endothelium-derived hyperpolarization mediated because it could not be blocked by N-nitro-l-arginine methyl ester (10−5 mol/l) and indomethacin (10−4 mol/l). We used GSK2193874 (10−7 mol/l) to confirm that in all groups this dilation was dependent on TRPV4 activation. Dilation in response to the TRPV4 agonist GSK1016790A (10−9–10−5 mol/l) was also reduced in hypertensive mice, and this defect was corrected by eplerenone. In hypertensive and eplerenone-treated animals, TRPV4 inhibition reduced myogenic tone, an effect that was not observed in arterioles from control animals. Eplerenone treatment also improved cognitive function and reduced microglia density in hypertensive mice. These data suggest that the mineralocorticoid receptor is a potential therapeutic target to improve cerebrovascular function and cognition during hypertension. NEW & NOTEWORTHY Vascular dementia is a growing public health issue that lacks effective treatments. Transient receptor potential vanilloid (TRPV)4 channels are important regulators of parenchymal arteriole dilation, and they modulate myogenic tone. The data presented here suggest that TRPV4 channel expression is regulated by the mineralocorticoid receptor (MR). MR blockade also improves cognitive function during hypertension. MR blockade might be a potential therapeutic approach to improve cerebrovascular function and cognition in patients with hypertension.

Renal angiotensin II concentration and interstitial infiltration of immune cells are correlated with blood pressure levels in salt-sensitive hypertension

2007 ◽  
Vol 293 (1) ◽  
pp. R251-R256 ◽  
Author(s):  
Martha Franco ◽  
Flavio Martínez ◽  
Yasmir Quiroz ◽  
Othir Galicia ◽  
Rocio Bautista ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Immune Cell ◽  
Salt Intake ◽  
Experimental Models ◽  
High Salt ◽  
Salt Diet ◽  
High Salt Intake ◽  
Plasma Angiotensin ◽  
Salt Sensitive Hypertension

Renal immune cell infiltration and cells expressing angiotensin II (AII) in tubulointerstitial areas of the kidney are features of experimental models of salt-sensitive hypertension (SSHTN). A high-salt intake tends to suppress circulating AII levels, but intrarenal concentrations of AII have not been investigated in SSHTN. This study explored the relationship between these features to gain insight into the pathophysiology of SSHTN. Plasma angiotensin II (AII) and renal interstitial AII (microdialysis technique) and the infiltration of macrophages, lymphocytes, and AII-positive cells were determined in SSHTN induced by 5 wk of a high-salt diet (HSD) after short-term infusion of AII in rats with ( n = 10) and without ( n = 11) treatment with mycophenolate mofetil (MMF) and in control rats fed a high- ( n = 7) and normal ( n = 11) salt diet. As in previous studies, MMF did not affect AII-associated hypertension but reduced the interstitial inflammation and the SSHTN in the post-AII-period. During the HSD period, the AII group untreated with MMF had mean ± SD) low plasma (2.4 ± 1.4 pg/ml) and high interstitial AII concentration (1,310 ± 208 pg/ml); MMF treatment resulted in a significantly lower interstitial AII (454 ± 128 pg/ml). Renal AII concentration and the number of tubulointerstitial AII-positive cells were correlated. Blood pressure correlated positively with interstitial AII and negatively with plasma AII, thus giving compelling evidence of the paramount role of the AII within the kidney in the AII-induced model of salt-driven hypertension.

scholarly journals Expression of claudin-8 is induced by aldosterone in renal collecting duct principal cells

2021 ◽  
Author(s):  
Ali Sassi ◽  
Yubao Wang ◽  
Alexandra Chassot ◽  
Isabelle Roth ◽  
Suresh Ramakrishnan ◽  
...  
Keyword(s):  
Tight Junction ◽  
Protein Kinases ◽  
Mineralocorticoid Receptor ◽  
Collecting Duct ◽  
Fine Tuning ◽  
Mrna Levels ◽  
Aldosterone Secretion ◽  
Mineralocorticoid Receptor Antagonist ◽  
Salt Diet ◽  
Principal Cells

Fine tuning of Na+reabsorption takes place along the aldosterone-sensitive distal nephron (ASDN) which includes the collecting duct (CD) where it is mainly regulated by aldosterone. In the CD,Na+ reabsorption is mediated by the epithelial sodium channel (ENaC) and the sodium pump (Na,K-ATPase). Paracellular ion permeability is mainly dependent on tight junction permeability. Claudin-8 is one of the main tight-junction proteins expressed along the ASDN. We have previously shown a coupling between trancellular Na+ reabsorption and paracellular Na+barrier. We hypothesize that aldosterone controls the expression levels of both transcellular Na+transporters and paracellular claudin-8 in a coordinated manner. Here, we show that aldosterone increased mRNA and protein levels as well as lateral membrane localization of claudin-8 in cultured CD principal cells. The increase in claudin-8 mRNA levels in response to aldosterone was prevented by preincubation with 17-hydroxy progesterone, a mineralocorticoid receptor antagonist, and by inhibition of transcription with actinomycin D. We also show that low salt diet which stimulated aldosterone secretion was associated with increased claudin-8 abundance in the mouse kidney. Reciprocally, mice subjected to high salt diet which inhibits aldosterone secretion or treated with spironolactone, a mineralocorticoid receptor (MR)antagonist, displayed decreased claudin-8 expression. Inhibition of glycogen synthase kinase-3 (GSK3), Lyn and Abl signaling pathways prevented the effect of aldosterone on claudin-8 mRNA and protein abundance, suggesting that signaling protein kinases plays a permissive role on the transcriptional activity of the mineralocorticoid receptor.This study shows that signaling via multiple protein kinases working in concert mediates the aldosterone-induced claudin-8 expression in collecting duct.

Increased central AT1-receptor activation, not systemic vasopressin, sustains hypertension in ANP knockout mice

2000 ◽  
Vol 278 (6) ◽  
pp. R1441-R1445 ◽  
Author(s):  
Uwe Ackermann ◽  
Newsha Azizi
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Receptor Antagonist ◽  
Knockout Mice ◽  
Blood Pressure Measurement ◽  
Receptor Activation ◽  
Wild Type ◽  
Vasopressin Release ◽  
Arterial Blood ◽  
Left Lateral Ventricle

We tested the hypothesis that hypertension in atrial natriuretic peptide (ANP) knockout mice is caused in part by disinhibition of angiotensin II-mediated vasopressin release. Inactin-anesthetized F2 homozygous ANP gene-disrupted mice (−/−) and wild-type (+/+) littermates were surgically prepared for carotid arterial blood pressure measurement (ABP) and background intravenous injection of physiological saline or vasopressin V1-receptor antagonist (Manning compound, 10 ng/g body wt) and subsequent intracerebroventricular (left lateral ventricle) injection of saline (5 μl) or ANP (0.5 μg) or angiotensin II AT1-receptor antagonist losartan (10 μg). Only (−/−) showed significant decrease in ABP after intracerebroventricular ANP or losartan. Both showed significant hypotension after intravenous V1 antagonist, but there was no difference between their responses. We conclude that 1) vasopressin contributes equally to ABP maintenance in ANP-disrupted mice and wild-type controls; 2) permanently elevated ABP in ANP knockouts is associated with increased central nervous angiotensin II AT1-receptor activation; 3) disinhibition of central nervous angiotensin II AT1receptors in ANP-deficient animals does not lead to a significant increase in the importance of vasopressin as a mechanism for blood pressure maintenance.

Angiotensin II Independent Mineralocorticoid Receptor Activation in Heart Failure Models

2008 ◽  
Vol 14 (7) ◽  
pp. S147
Author(s):  
Tomomi Meguro ◽  
Yuji Nagatomo ◽  
Kimi Koide ◽  
Hiroyuki Ito ◽  
Toshihisa Anzai ◽  
...  
Keyword(s):  
Heart Failure ◽  
Angiotensin Ii ◽  
Mineralocorticoid Receptor ◽  
Receptor Activation ◽  
Failure Models

scholarly journals Dietary Fructose Increases the Sensitivity of Proximal Tubules to Angiotensin II in Rats Fed High-Salt Diets

Nutrients ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1244 ◽  
Author(s):  
Agustin Gonzalez-Vicente ◽  
Nancy Hong ◽  
Nianxin Yang ◽  
Pablo Cabral ◽  
Jessica Berthiaume ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Tap Water ◽  
Transport Processes ◽  
High Salt ◽  
Proximal Tubules ◽  
Ang Ii ◽  
High Salt Diet ◽  
Salt Diet ◽  
Dietary Fructose ◽  
Salt Sensitive Hypertension

Dietary fructose causes salt-sensitive hypertension. Proximal tubules (PTs) reabsorb 70% of the filtered NaCl. Angiotensin II (Ang II), atrial natriuretic peptide (ANP) and norepinephrine (NE) regulate this process. Although Ang II signaling blockade ameliorates fructose-induced salt-sensitive hypertension, basal PT Na+ reabsorption and its sensitivity to the aforementioned factors have not been studied in this model. We hypothesized consuming fructose with a high-salt diet selectively enhances the sensitivity of PT transport to Ang II. We investigated the effects of Ang II, ANP and NE on PT Na reabsorption in rats fed a high-salt diet drinking tap water (HS) or 20% fructose (HS-FRU). Oxygen consumption (QO2) was used as a measure of all ATP-dependent transport processes. Na+/K+-ATPase and Na+/H+-exchange (NHE) activities were studied because they represent primary apical and basolateral transporters in this segment. The effect of 10−12 mol/L Ang II in QO2 by PTs from HS-FRU was larger than HS (p < 0.02; n = 7). In PTs from HS-FRU 10−12 mol/L Ang II stimulated NHE activity by 2.6 ± 0.7 arbitrary fluorescence units/s (p < 0.01; n = 5) but not in those from HS. The stimulatory effect of Ang II on PT Na+/K+-ATPase activity was not affected by HS-FRU. Responses of QO2 and NHE activity to ANP did not differ between groups. The response of QO2 to NE was unaltered by HS-FRU. We concluded that the sensitivity of PT Na+ reabsorption specifically to Ang II is enhanced by HS-FRU. This maintains high rates of transport even in the presence of low concentrations of the peptide, and likely contributes to the hypertension.

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