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Watanabe H, Belyea BC, Paxton RL, Li M, Dzamba BJ, DeSimone DW, Gomez RA, Sequeira-Lopez MLS. Renin Cell Baroreceptor, a Nuclear Mechanotransducer Central for Homeostasis. Circ Res 2021; 129:262-276. [PMID: 33993729 PMCID: PMC8273135 DOI: 10.1161/circresaha.120.318711] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
[Figure: see text].
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Affiliation(s)
- Hirofumi Watanabe
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Brian C. Belyea
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Robert L. Paxton
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Minghong Li
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Bette J. Dzamba
- Department of Cell Biology, University of Virginia, School of Medicine, Charlottesville, Virginia
| | - Douglas W. DeSimone
- Department of Cell Biology, University of Virginia, School of Medicine, Charlottesville, Virginia
| | - R. Ariel Gomez
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Maria Luisa S. Sequeira-Lopez
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
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Bjørnholm KD, Ougaard ME, Skovsted GF, Knudsen LB, Pyke C. Activation of the renal GLP-1R leads to expression of Ren1 in the renal vascular tree. ENDOCRINOLOGY DIABETES & METABOLISM 2021; 4:e00234. [PMID: 34277961 PMCID: PMC8279630 DOI: 10.1002/edm2.234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/19/2021] [Accepted: 01/29/2021] [Indexed: 02/06/2023]
Abstract
The GLP‐1 receptor (GLP‐1R) in the kidney is expressed exclusively in vascular smooth muscle cells in arteries and arterioles. Downstream effects of the activation of the renal vascular GLP‐1R are elusive but may involve regulation of the renin‐angiotensin‐aldosterone system (RAAS). The expression of Ren1 in the mouse renal vasculature was investigated by in situ hybridization after a single subcutaneous dose of liraglutide, semaglutide and after repeated injections of liraglutide. Single and repeated exposure to GLP‐1R agonists induced expression of Ren1 in the renal vascular smooth muscle cell compartment compared with vehicle injected controls (p < .0001) for both semaglutide and liraglutide. The present data show a robust induction of Ren1 expression in the vascular smooth muscle cells of the kidney after single and repeated GLP‐1R activation and this renin recruitment may be involved in the effects of GLP‐1R agonist treatment on kidney disease.
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Affiliation(s)
- Katrine Dahl Bjørnholm
- Department of Experimental Animal Models University of Copenhagen Frederiksberg Denmark.,Department of Cardiovascular Research Novo Nordisk A/S Måløv Denmark
| | | | - Gry Freja Skovsted
- Department of Experimental Animal Models University of Copenhagen Frederiksberg Denmark
| | | | - Charles Pyke
- Department of Pathology and Imaging Novo Nordisk A/S Måløv Denmark
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Abstract
An accumulating body of evidence suggests that renin-expressing cells have developed throughout evolution as a mechanism to preserve blood pressure and fluid volume homeostasis as well as to counteract a number of homeostatic and immunological threats. In the developing embryo, renin precursor cells emerge in multiple tissues, where they differentiate into a variety of cell types. The function of those precursors and their progeny is beginning to be unravelled. In the developing kidney, renin-expressing cells control the morphogenesis and branching of the renal arterial tree. The cells do not seem to fully differentiate but instead retain a degree of developmental plasticity or molecular memory, which enables them to regenerate injured glomeruli or to alter their phenotype to control blood pressure and fluid-electrolyte homeostasis. In haematopoietic tissues, renin-expressing cells might regulate bone marrow differentiation and participate in a circulating leukocyte renin-angiotensin system, which acts as a defence mechanism against infections or tissue injury. Furthermore, renin-expressing cells have an intricate lineage and functional relationship with erythropoietin-producing cells and are therefore central to two endocrine systems - the renin-angiotensin and erythropoietin systems - that sustain life by controlling fluid volume and composition, perfusion pressure and oxygen delivery to tissues. However, loss of the homeostatic control of these systems following dysregulation of renin-expressing cells can be detrimental, with serious pathological events.
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Oka M, Medrano S, Sequeira-Lόpez MLS, Gómez RA. Chronic Stimulation of Renin Cells Leads to Vascular Pathology. Hypertension 2017; 70:119-128. [PMID: 28533331 DOI: 10.1161/hypertensionaha.117.09283] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 03/09/2017] [Accepted: 04/04/2017] [Indexed: 01/14/2023]
Abstract
Experimental or spontaneous genomic mutations of the renin-angiotensin system or its pharmacological inhibition in early life leads to renal abnormalities, including poorly developed renal medulla, papillary atrophy, hydronephrosis, inability to concentrate the urine, polyuria, polydipsia, renal failure, and anemia. At the core of such complex phenotype is the presence of unique vascular abnormalities: the renal arterioles do not branch or elongate properly and they have disorganized, concentric hypertrophy. This lesion has been puzzling because it is often found in hypertensive individuals whereas mutant or pharmacologically inhibited animals are hypotensive. Remarkably, when renin cells are ablated with diphtheria toxin, the vascular hypertrophy does not occur, suggesting that renin cells per se may contribute to the vascular disease. To test this hypothesis, on a Ren1c-/- background, we generated mutant mice with reporter expression (Ren1c-/-;Ren1c-Cre;R26R.mTmG and Ren1c-/-;Ren1c-Cre;R26R.LacZ) to trace the fate of reninnull cells. To assess whether reninnull cells maintain their renin promoter active, we used Ren1c-/-;Ren1c-YFP mice that transcribe YFP (yellow fluorescent protein) directed by the renin promoter. We also followed the expression of Akr1b7 and miR-330-5p, markers of cells programmed for the renin phenotype. Contrary to what we expected, reninnull cells did not die or disappear. Instead, they survived, increased in number along the renal arterial tree, and maintained an active molecular memory of the myoepitheliod renin phenotype. Furthermore, null cells of the renin lineage occupied the walls of the arteries and arterioles in a chaotic, directionless pattern directly contributing to the concentric arterial hypertrophy.
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Affiliation(s)
- Masafumi Oka
- From the Department of Pediatrics, University of Virginia, Charlottesville
| | - Silvia Medrano
- From the Department of Pediatrics, University of Virginia, Charlottesville
| | | | - R Ariel Gómez
- From the Department of Pediatrics, University of Virginia, Charlottesville.
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Gomez RA, Sequeira-Lopez MLS. Novel Functions of Renin Precursors in Homeostasis and Disease. Physiology (Bethesda) 2017; 31:25-33. [PMID: 26661526 DOI: 10.1152/physiol.00039.2015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Renin progenitors appear early and are found in multiple tissues throughout the embryo. Besides their well known role in blood pressure and fluid homeostasis, renin progenitors participate in tissue morphogenesis, repair, and regeneration, and may integrate immune and endocrine responses. In the bone marrow, renin cells offer clues to understand normal and neoplastic hematopoiesis.
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Affiliation(s)
- R Ariel Gomez
- University of Virginia School of Medicine, Child Health Research Center, Charlottesville, Virginia
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Gomez RA, Belyea B, Medrano S, Pentz ES, Sequeira-Lopez MLS. Fate and plasticity of renin precursors in development and disease. Pediatr Nephrol 2014; 29:721-6. [PMID: 24337407 PMCID: PMC3999616 DOI: 10.1007/s00467-013-2688-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 10/04/2013] [Accepted: 10/28/2013] [Indexed: 01/04/2023]
Abstract
Renin-expressing cells appear early in the embryo and are distributed broadly throughout the body as organogenesis ensues. Their appearance in the metanephric kidney is a relatively late event in comparison with other organs such as the fetal adrenal gland. The functions of renin cells in extra renal tissues remain to be investigated. In the kidney, they participate locally in the assembly and branching of the renal arterial tree and later in the endocrine control of blood pressure and fluid-electrolyte homeostasis. Interestingly, this endocrine function is accomplished by the remarkable plasticity of renin cell descendants along the kidney arterioles and glomeruli which are capable of reacquiring the renin phenotype in response to physiological demands, increasing circulating renin and maintaining homeostasis. Given that renin cells are sensors of the status of the extracellular fluid and perfusion pressure, several signaling mechanisms (β-adrenergic receptors, Notch pathway, gap junctions and the renal baroreceptor) must be coordinated to ensure the maintenance of renin phenotype--and ultimately the availability of renin--during basal conditions and in response to homeostatic threats. Notably, key transcriptional (Creb/CBP/p300, RBP-J) and posttranscriptional (miR-330, miR125b-5p) effectors of those signaling pathways are prominent in the regulation of renin cell identity. The next challenge, it seems, would be to understand how those factors coordinate their efforts to control the endocrine and contractile phenotypes of the myoepithelioid granulated renin-expressing cell.
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Affiliation(s)
- R Ariel Gomez
- Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, Room 2001, Charlottesville, VA, 22908, USA,
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Neubauer B, Machura K, Kettl R, Lopez MLSS, Friebe A, Kurtz A. Endothelium-derived nitric oxide supports renin cell recruitment through the nitric oxide-sensitive guanylate cyclase pathway. Hypertension 2013; 61:400-7. [PMID: 23297374 DOI: 10.1161/hypertensionaha.111.00221] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chronic challenge of renin-angiotensin causes recruitment of renin-producing cells in the kidney along the media layer of afferent arterioles and hypertrophy of cells in the juxtaglomerular apparatus. This study aimed to define the role of nitric oxide (NO) with regard to the recruitment pattern of renin-producing cells and to the possible pathways along which NO could act. We considered the hypothesis that endothelium-derived NO acts via NO-sensitive guanylate cyclase. Mice were treated with low-salt diet in combination with the angiotensin I-converting enzyme inhibitor enalapril for 3 weeks, which led to a 13-fold increase in renin expression associated with marked recruitment of renin cells in afferent arterioles and hypertrophy of the juxtaglomerular apparatus in wild-type mice. In wild-type mice additionally treated with the nonselective NO synthase inhibitor L-NAME, the recruitment of renin-expressing cells along the afferent arterioles was absent and juxtaglomerular hypertrophy was diminished. An almost identical attenuation of renin cell recruitment as with L-NAME treatment in wild-type mice was found in mice lacking the endothelial isoform of NO synthase. Treatment of mice lacking NO-sensitive guanylate cyclase in renin-expressing cells and preglomerular smooth muscle cells with low-salt diet in combination with the angiotensin I-converting enzyme inhibitor enalapril for 3 weeks produced juxtaglomerular hypertrophy like in wild-type mice, but no recruitment in afferent arterioles. These findings suggest that endothelium-derived NO and concomitant formation of cGMP in preglomerular renin cell precursors supports recruitment of renin-expressing cells along preglomerular vessels, but not in the juxtaglomerular apparatus.
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Affiliation(s)
- Björn Neubauer
- Institute of Physiology, University of Regensburg, Regensburg, Germany.
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Pentz ES, Cordaillat M, Carretero OA, Tucker AE, Sequeira Lopez MLS, Gomez RA. Histone acetyl transferases CBP and p300 are necessary for maintenance of renin cell identity and transformation of smooth muscle cells to the renin phenotype. Am J Physiol Heart Circ Physiol 2012; 302:H2545-52. [PMID: 22523253 DOI: 10.1152/ajpheart.00782.2011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In response to a homeostatic threat circulating renin increases by increasing the number of cells expressing renin by dedifferentiation and re-expression of renin in arteriolar smooth muscle cells (aSMCs) that descended from cells that expressed renin in early life. However, the mechanisms that govern the maintenance and reacquisition of the renin phenotype are not well understood. The cAMP pathway is important for renin synthesis and release: the transcriptional effects are mediated by binding of cAMP responsive element binding protein with its co-activators, CBP and p300, to the cAMP response element in the renin promoter. We have shown previously that mice with conditional deletion of CBP and p300 (cKO) in renin cells had severely reduced renin expression in adult life. In this study we investigated when the loss of renin-expressing cells in the cKO occurred and found that the loss of renin expression becomes evident after differentiation of the kidney is completed during postnatal life. To determine whether CBP/p300 is necessary for re-expression of renin we subjected cKO mice to low sodium diet + captopril to induce retransformation of aSMCs to the renin phenotype. The cKO mice did not increase circulating renin, their renin mRNA and protein expression were greatly diminished compared with controls, and only a few aSMCs re-expressed renin. These studies underline the crucial importance of the CREB/CBP/p300 complex for the ability of renin cells to retain their cellular memory and regain renin expression, a fundamental survival mechanism, in response to a threat to homeostasis.
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Affiliation(s)
- Ellen Steward Pentz
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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Castellanos Rivera RM, Monteagudo MC, Pentz ES, Glenn ST, Gross KW, Carretero O, Sequeira-Lopez MLS, Gomez RA. Transcriptional regulator RBP-J regulates the number and plasticity of renin cells. Physiol Genomics 2011; 43:1021-8. [PMID: 21750232 DOI: 10.1152/physiolgenomics.00061.2011] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Renin-expressing cells are crucial in the control of blood pressure and fluid-electrolyte homeostasis. Notch receptors convey cell-cell signals that may regulate the renin cell phenotype. Because the common downstream effector for all Notch receptors is the transcription factor RBP-J, we used a conditional knockout approach to delete RBP-J in cells of the renin lineage. The resultant RBP-J conditional knockout (cKO) mice displayed a severe reduction in the number of renin-positive juxtaglomerular apparatuses (JGA) and a reduction in the total number of renin positive cells per JGA and along the afferent arterioles. This reduction in renin protein was accompanied by a decrease in renin mRNA expression, decreased circulating renin, and low blood pressure. To investigate whether deletion of RBP-J altered the ability of mice to increase the number of renin cells normally elicited by a physiological threat, we treated RBP-J cKO mice with captopril and sodium depletion for 10 days. The resultant treated RBP-J cKO mice had a 65% reduction in renin mRNA levels (compared with treated controls) and were unable to increase circulating renin. Although these mice attempted to increase the number of renin cells, the cells were unusually thin and had few granules and barely detectable amounts of immunoreactive renin. As a consequence, the cells were incapable of fully adopting the endocrine phenotype of a renin cell. We conclude that RBP-J is required to maintain basal renin expression and the ability of smooth muscle cells along the kidney vasculature to regain the renin phenotype, a fundamental mechanism to preserve homeostasis.
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Affiliation(s)
- Ruth M Castellanos Rivera
- Department of Pediatrics, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
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Pentz ES, Lopez MLSS, Cordaillat M, Gomez RA. Identity of the renin cell is mediated by cAMP and chromatin remodeling: an in vitro model for studying cell recruitment and plasticity. Am J Physiol Heart Circ Physiol 2007; 294:H699-707. [PMID: 18055510 DOI: 10.1152/ajpheart.01152.2007] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The renin-angiotensin system (RAS) regulates blood pressure and fluid-electrolyte homeostasis. A key step in the RAS cascade is the regulation of renin synthesis and release by the kidney. We and others have shown that a major mechanism to control renin availability is the regulation of the number of cells capable of making renin. The kidney possesses a pool of cells, mainly in its vasculature but also in the glomeruli, capable of switching from smooth muscle to endocrine renin-producing cells when homeostasis is threatened. The molecular mechanisms governing the ability of these cells to turn the renin phenotype on and off have been very difficult to study in vivo. We, therefore, developed an in vitro model in which cells of the renin lineage are labeled with cyan fluorescent protein and cells actively making renin mRNA are labeled with yellow fluorescent protein. The model allowed us to determine that it is possible to culture cells of the renin lineage for numerous passages and that the memory to express the renin gene is maintained in culture and can be reenacted by cAMP and chromatin remodeling (histone H4 acetylation) at the cAMP-responsive element in the renin gene.
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Affiliation(s)
- Ellen Steward Pentz
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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Sahajpal V, Ashton N. Increased glomerular angiotensin II binding in rats exposed to a maternal low protein diet in utero. J Physiol 2004; 563:193-201. [PMID: 15611024 PMCID: PMC1665576 DOI: 10.1113/jphysiol.2004.078642] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In the rat, protein restriction during pregnancy increases offspring blood pressure by 20-30 mmHg. We have shown in an earlier study that this is associated with a reduction in nephron number and increased glomerular sensitivity to angiotensin II (Ang II) in vivo. Hence, we hypothesized that exposure to a maternal low-protein diet increases glomerular Ang II AT1 receptor expression and decreases AT2 receptor expression. To test this hypothesis, pregnant Wistar rats were fed isocalorific diets containing either 18% (control) or 9% (LP) protein from conception until birth. At 4 weeks of age, the kidneys of male offspring were harvested to measure cortical AT1 and AT2 receptor expression, 125I-Ang II glomerular binding, tissue renin activity, tissue Ang II and plasma aldosterone concentrations. AT1 receptor expression was increased (62%) and AT2 expression was decreased (35%) in LP rats. Maximum 125I-Ang II (125I-Ang II) binding (Bmax) was increased in LP rats (control n = 9, 291.6 +/- 27.4 versus LP n = 7, 445.7 +/- 27.4 fmol (mg glomerular protein)(-1), P < 0.01), but affinity (KD) was not statistically different from controls (control 2.87 +/- 0.85 versus LP 0.84 +/- 0.20 pmol 125I-Ang II, P = 0.059). Renal renin activity, tissue Ang II and plasma aldosterone concentrations did not differ between control and LP rats. Increased AT1 receptor expression in LP rat kidneys is consistent with greater haemodynamic sensitivity to Ang II in vivo. This may result in an inappropriate reduction in glomerular filtration rate, salt and water retention, and an increase in blood pressure.
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Affiliation(s)
- Vandana Sahajpal
- Faculty of Life Sciences, University of Manchester, G.38 Stopford Building, Oxford Road, Manchester M13 9PT, UK
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Mangrum AJ, Gomez RA, Norwood VF. Effects of AT(1A) receptor deletion on blood pressure and sodium excretion during altered dietary salt intake. Am J Physiol Renal Physiol 2002; 283:F447-53. [PMID: 12167595 DOI: 10.1152/ajprenal.00259.2001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study was performed to investigate the role of type 1A ANG II (AT(1A)) receptors in regulating sodium balance and blood pressure maintenance during chronic dietary sodium variations in AT(1A) receptor-deficient (-/-) mice. Groups of AT(1A) (-/-) and wild-type mice were placed on a low (LS)-, normal (NS)-, or high-salt (HS) diet for 3 wk. AT(1A) (-/-) mice on an LS diet had high urinary volume and low blood pressure despite increased renin and aldosterone levels. On an HS diet, (-/-) mice demonstrated significant diuresis, yet blood pressure increased to levels greater than control littermates. There was no effect of dietary sodium intake on systolic blood pressures in wild-type animals. The pressure-natriuresis relationship in AT(1A) (-/-) mice demonstrated a shift to the left and a decreased slope compared with wild-type littermates. These studies demonstrate that mice lacking the AT(1A) receptor have blood pressures sensitive to changes in dietary sodium, marked alterations of the pressure-natriuresis relationship, and compensatory mechanisms capable of maintaining normal sodium balance across a wide range of sodium intakes.
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Affiliation(s)
- Amy J Mangrum
- Department of Internal Medicine, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
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Ryan MJ, Black TA, Gross KW, Hajduczok G. Cyclic mechanical distension regulates renin gene transcription in As4.1 cells. Am J Physiol Endocrinol Metab 2000; 279:E830-7. [PMID: 11001765 DOI: 10.1152/ajpendo.2000.279.4.e830] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The renin-producing and -secreting juxtaglomerular (JG) cells are thought to function as the baroreceptor of the kidney. The mechanism by which changes in pressure, or mechanical force, regulate renin at the molecular level has not been elucidated. The renin gene-expressing and -secreting clonal cell line As4.1 was derived from transgene-targeted oncogenesis in mice and was used as a cellular model for JG cells. As4.1 cells subjected to cyclic mechanical distension for a period of 24 h at various frequencies (0. 05 or 0.5 Hz) and magnitudes (12 or 24% elongation) were analyzed via Northern analysis for renin mRNA levels. Results indicate that renin gene expression is decreased by 50-85% and returns to basal levels after a 24-h recovery period. Renin gene expression was attenuated independently of elevated cell growth or changes in renin message decay, suggesting that renin gene transcription is directly modulated by mechanical distension. Transient transfection of As4.1 cells with renin 5' flanking sequence-luciferase reporter gene constructs confirmed the role of mechanical stimulation in regulating renin gene transcription. A 43% inhibition of luciferase activity, by stretch, was observed in cells transfected with a 4,000 base pair 5' flanking sequence to the renin proximal promoter. These results demonstrate for the first time that changes in mechanical force can result in the regulation of renin gene transcription and thus provide further insight into the baroreceptor properties of renin-expressing cells.
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Affiliation(s)
- M J Ryan
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo 14214, USA
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Moosavi SM, Johns EJ. Effect of renal perfusion pressure on renal function, renin release and renin and angiotensinogen gene expression in rats. J Physiol 1999; 520 Pt 1:261-9. [PMID: 10517817 PMCID: PMC2269577 DOI: 10.1111/j.1469-7793.1999.t01-1-00261.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. A study was undertaken to examine the influence of acute renal perfusion pressure (RPP) reduction on renin release, renal renin and angiotensinogen gene expression and the role played by angiotensin II in these responses. 2. In chloralose-urethane anaesthetised rats, reduction of RPP to 60 mmHg for 3 h in vehicle or losartan-treated (5 days at 10 mg kg-1 bis in die (b.i.d.)) rats decreased renal blood flow by 46 and 29 % (both P < 0.001), respectively, glomerular filtration rate by 45 and 57 % (both P < 0.001), respectively, and sodium excretion by 96 and 98 % (both P < 0.01). 3. Chloralose-urethane anaesthesia and surgery caused a rise in plasma renin activity but was associated with a suppression of renal renin (50 %, P < 0.01) and angiotensinogen (40 %, P < 0.05) gene expression. Following reduction of RPP to 60 mmHg for 3 h, plasma renin activity was increased more than 7-fold (P < 0.001) and renal renin gene expression about 2-fold (P < 0.05). 4. Chronic (5 days) blockade of angiotensin II receptors with losartan elevated plasma renin activity some 29-fold (P < 0.001) and caused a marked increase (30-fold, P < 0.05) in renal renin gene expression, compatible with angiotensin II exerting a negative feedback control on renin release and gene expression. Reduction of RPP to 60 mmHg for 3 h in these animals had little effect on renal renin gene expression. 5. From these findings it can be concluded that (a) chloralose-urethane anaesthesia and surgery had a stimulatory effect on renin release but suppressed basal levels of renal renin and angiotensinogen gene expression; (b) acute reduction of RPP for 3 h could stimulate renin gene expression in the renin producing cells; and (c) the negative feedback control of angiotensin II on renin release and synthesis which was evident following chronic losartan treatment was not apparent during short-term reduction of RPP.
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Affiliation(s)
- S M Moosavi
- Department of Physiology, The Medical School, Birmingham B15 2TT, UK
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16
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Carey RM, McGrath HE, Pentz ES, Gomez RA, Barrett PQ. Biomechanical coupling in renin-releasing cells. J Clin Invest 1997; 100:1566-74. [PMID: 9294125 PMCID: PMC508338 DOI: 10.1172/jci119680] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The renin-angiotensin system is a major regulatory system controlling extracellular fluid volume and blood pressure. The rate-limiting enzyme in this hormonal cascade is renin, which is synthesized and secreted into the circulation by renal juxtaglomerular (JG) cells. The renal baroreceptor is a key physiologic regulator of renin secretion, whereby a change in renal perfusion pressure is sensed by these cells and results in a change in renin release. However, the mechanism, direct or indirect, underlying pressure transduction is unknown. We studied the direct application of mechanical stretch to rat JG cells and human renin-expressing (CaLu-6) cells on the release of renin. JG cells released a low level of baseline renin, comprising < 5% of their total renin content. By contrast, renin secretion from CaLu-6 cells comprised approximately 30% of cellular stores, yet was also stimulated twofold by 10 microM forskolin (P </= 0.001). In JG cells, mechanical stretch inhibited basal renin release by 42% (P < 0.01) and forskolin-stimulated renin release by 25% (P < 0.05). In CaLu-6 cells, stretch inhibited basal- and forskolin-stimulated renin release by 30 and 26%, respectively (both P < 0.01). Northern blot analysis demonstrated a stretch-induced reduction in baseline renin mRNA accumulation of 26% (P < 0.05) in JG and 46% (P < 0.05) in CaLu-6 cells. The data demonstrate that mechanical stretch in renin-releasing cells inhibits basal and stimulated renin release accompanied by a decrease in renin mRNA accumulation. Further studies will be necessary to characterize the intracellular events mediating biomechanical coupling in renin-expressing cells and the relationship of this signaling pathway to the in vivo baroreceptor control of renin secretion.
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Affiliation(s)
- R M Carey
- Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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Abstract
Molecular, cellular, and physiological studies indicate that the renin-angiotensin system (RAS) is highly expressed during early kidney development. We propose that a major function of the RAS during early embryonic development is the modulation of growth processes that lead the primitive kidney into a properly differentiated and architecturally organized organ suited for independent extrauterine life. As development progresses, the RAS acquires new and overlapping functions such as the endocrine and paracrine regulation of blood pressure and renal hemodynamics. Disease states in adult mammals often result in expression of RAS genes and phenotypic changes resembling the embryonic pattern, emphasizing the importance of undertaking developmental studies. Because of their importance in health and disease, the immediate challenge is to identify the mechanisms that regulate the unique development of the RAS and its role(s) in normal and abnormal growth processes.
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Affiliation(s)
- R A Gomez
- Department of Pediatrics, University of Virginia Health Sciences Center, Charlottesville 22908, USA
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Schricker K, Hegyi I, Hamann M, Kaissling B, Kurtz A. Tonic stimulation of renin gene expression by nitric oxide is counteracted by tonic inhibition through angiotensin II. Proc Natl Acad Sci U S A 1995; 92:8006-10. [PMID: 7644529 PMCID: PMC41275 DOI: 10.1073/pnas.92.17.8006] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
This study was designed to examine the possible involvement of prostaglandins and nitric oxide (NO) in the renin stimulatory effect of angiotensin II (AngII) antagonists. To this end, plasma renin activities (PRAs) and renal renin mRNA levels were assayed in rats that were treated with the Ang-converting enzyme inhibitor ramipril or with the AngII AT1-receptor antagonist losartan. Ramipril and losartan increased PRA values from 7.5 +/- 1.6 to 86 +/- 6 and 78 +/- 22 ng of AngI per h per ml and renin mRNA levels from 112 +/- 9% to 391 +/- 20% and 317 +/- 10%, respectively. Inhibition of prostaglandin formation with indomethacin did not influence basal or ramipril-affected PRA. Basal renin mRNA levels also were unchanged by indomethacin, while increases in renin mRNA levels after ramipril treatment were slightly reduced by indomethacin. Inhibition of NO synthase by nitro-L-arginine methyl ester (L-NAME) reduced PRA values to 3.2 +/- 0.9, 34 +/- 13, and 12.1 +/- 2.7 ng of AngI per h per ml in control, ramipril-treated, and losartan-treated animals, respectively. Renin mRNA levels were reduced to 77 +/- 14% under basal conditions and ramipril- and losartan-induced increases in renin mRNA levels were completely blunted after addition of L-NAME. The AngII antagonists, furthermore, induced an upstream recruitment of renin-expressing cells in the renal afferent arterioles, which was also blunted by L-NAME. These findings suggest that renin mRNA levels are tonically increased by NO and that the action of NO is counteracted by AngII.
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Affiliation(s)
- K Schricker
- Physiologisches Institut der Universität Regensburg, Germany
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Du Y, Yao A, Guo D, Inagami T, Wang DH. Differential regulation of angiotensin II receptor subtypes in rat kidney by low dietary sodium. Hypertension 1995; 25:872-7. [PMID: 7721446 DOI: 10.1161/01.hyp.25.4.872] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This study was designed to determine whether expression of renal messenger RNA (mRNA) encoding the two known angiotensin II type 1 (AT1) receptor subtypes (AT1A and AT1B) can be regulated by dietary sodium. Seven-week-old male Wistar rats were fed a low-sodium diet (0.07%, n = 9) or a normal-sodium diet (0.5%, n = 9 [control]) for 14 days. A rat AT1 complementary DNA (cDNA) probe, which hybridizes to mRNA encoding both the AT1A and AT1B receptor subtypes, and cDNA probes, which are selective for AT1A or AT1B mRNA, were used in Northern blot or in situ hybridization analysis. By use of Northern blot analysis, renal mRNA levels for the AT1 and AT1A receptors in rats fed a low-sodium diet were found to be increased twofold (P < .05) compared with control. Because renal AT1B mRNA content was not detected by Northern blot analysis, quantitative image analysis of in situ hybridization with a digoxigenin-labeled cRNA probe made from AT1B cDNA was used. In situ hybridization analysis indicated that AT1B mRNA was expressed in the proximal and collecting tubules of the kidney in rats fed a normal-sodium diet. The low-sodium diet significantly decreased the percent positive staining area of AT1B mRNA in the renal cortex (5.51 +/- 0.77% versus 2.73 +/- 0.35%, P < .05) and medulla (4.76 +/- 0.70% versus 2.01 +/- 0.43%, P < .05) compared with the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- Y Du
- Department of Internal Medicine, Hypertension and Vascular Research, University of Texas Medical Branch, Galveston 77555-1065, USA
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Li Q, Brownfield MS, Levy AD, Battaglia G, Cabrera TM, Van de Kar LD. Attenuation of hormone responses to the 5-HT1A agonist ipsapirone by long-term treatment with fluoxetine, but not desipramine, in male rats. Biol Psychiatry 1994; 36:300-8. [PMID: 7993956 DOI: 10.1016/0006-3223(94)90627-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The present study had two objectives: (1) to provide information on neuroendocrine challenge tests that can lead to diagnostic tests in humans; and (2) to confirm our previous observation that chronic fluoxetine selectively inhibits serotonin (5-HT1A) receptor function. We determined the effect of chronic fluoxetine and desipramine (DMI) on the hormone response to ipsapirone, a 5-HT1A agonist and a potential anxiolytic drug. Ipsapirone increased oxytocin, adrenocorticotropic hormone (ACTH), corticosterone, and prolactin, but not renin or vasopressin concentrations in plasma. Chronic fluoxetine, but not DMI, significantly inhibited the effect of ipsapirone on plasma oxytocin, ACTH and corticosterone concentrations. Chronic fluoxetine also reduced the Bmax for 3H-8-hydroxy-2-(dipropylamino) tetralin (3H-8-OH-DPAT) labelled 5-HT1A receptors in the midbrain. Neither antidepressant altered the density or affinity of 5-HT uptake sites. In conclusion, the present results confirm our previous results using 8-OH-DPAT as a challenge, and suggest that chronic 5-HT uptake inhibition results in adaptive changes leading to decreased function of the 5-HT1A receptor system. Finally, because ipsapirone may be administered to humans, it might be usable to evaluate 5-HT1A receptor function in depressed patients.
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Affiliation(s)
- Q Li
- Department of Pharmacology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL
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