Identification of a Nuclear Orphan Receptor (Ear2) as a Negative Regulator of Renin Gene Transcription

Liu, Xuebo; Huang, Xiao-Dong; Sigmund, Curt D.

doi:10.1161/01.res.0000071355.82009.43

Cited by 57 publications

(75 citation statements)

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“…An NF-Y binding site overlaps with the binding site for RAR␣/RXR and may thus prevent the binding of factors to the RARE (13). Ear2, an orphan member of the steroid hormone superfamily is a potent inhibitor of thyroid hormone receptor, luteinizing hormone receptor, and renin expression (15,31,32). In the renin enhancer, Ear2 shares the same binding site as RAR␣/RXR.…”

Section: Discussionmentioning

confidence: 99%

“…A sequence with 75-85% homology was also identified ϳ6 kb upstream of the rat and 11-kb upstream of the human RENIN (hREN) gene (10,11). Detailed analysis of the enhancer using an immortalized renin-expressing JG cell line in vitro has led many to conclude that a minimum of 10 different transcription factors exhibiting either stimulatory and inhibitory effects on renin expression may bind to the enhancer (12)(13)(14)(15)(16). Sequences in the enhancer also appear necessary to mediate the inhibitory effect of cytokines (17)(18)(19)(20)(21).…”

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confidence: 99%

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The Human Renin Kidney Enhancer Is Required to Maintain Base-line Renin Expression but Is Dispensable for Tissue-specific, Cell-specific, and Regulated Expression

Zhoux

Davis

2006

Journal of Biological Chemistry

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Renin is the rate-limiting enzyme in the renin-angiotensin system and thus dictates the level of the pressor hormone angiotensin-II. The classical site of renin expression and secretion is the renal juxtaglomerular cell, where its expression is tightly regulated by physiological cues. An evolutionarily conserved transcriptional enhancer located 11 kb upstream of the human RENIN gene has been reported to markedly enhance transcription in renin expressing cells in vitro. However, its importance in vivo remains unclear. We tested whether this enhancer is required for appropriate tissue-and cell-specific expression, or for physiological regulation of the human RENIN gene. To accomplish this, we used a retrofitting technique employing homologous recombination in bacteria to delete the enhancer from a 160-kb P1-artificial chromosome containing human RENIN, two upstream genes and one downstream gene, and then generated two lines of transgenic mice. We previously showed that human renin expression in transgenic mice containing the wild type construct is tightly regulated as is expression of the linked genes. Deletion of the enhancer had no effect on tissue-specific expression of human RENIN, but using the downstream gene as an internal control, found that human RENIN mRNA levels were 3-10-fold decreased compared with constructs containing the enhancer. Despite this decrease in expression, renin protein remained localized to renal juxtaglomerular cells and was appropriately regulated by cues that either increase or decrease expression of renin. Our results suggest that sequences other than the enhancer may be necessary for tissue-specific, cell-specific, and regulated expression of human RENIN.Renin is the first and rate-limiting aspartyl protease in the renin-angiotensin system (RAS) 2 cascade that leads to the production of angiotensin-II (Ang-II) by the consecutive cleavage of angiotensinogen by renin and angiotensin-I by angiotensin converting enzyme. Ang-II is an important regulator of cardiovascular function, stimulating vasoconstriction, cardiac output, aldosterone synthesis, and sympathetic activity, thereby directly and indirectly enhancing peripheral vascular resistance and renal tubular water and salt reabsorption. The critical importance of the RAS is evidenced by gene targeted ablation of the RAS genes in mice. The elimination of any RAS gene in mice causes cardiovascular consequences that include hypotension and renal insufficiency, and developmental consequences including postnatal lethality (1-4). The cardiovascular and developmental defects can be complemented in mice by substitution of the mouse RAS with their human orthologs (5) or by targeted expression of Ang-II (6). In humans, genetic defects in the RAS were reported to cause renal tubular dysgenesis, hypotension, and early stillbirth (7). Consequently, both the mouse and human genetic data illustrate the importance of the system both developmentally and in adults.Renin is primarily expressed in renal juxtaglomerular (JG) cells in the wall of the af...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

The Human Renin Kidney Enhancer Is Required to Maintain Base-line Renin Expression but Is Dispensable for Tissue-specific, Cell-specific, and Regulated Expression

Zhoux

Davis

2006

Journal of Biological Chemistry

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“…19 In addition, also the nuclear orphan receptor EAR2 has been shown to bind to the TGACCT motif. 20 Although retinoic acid is responsible for upregulation of renin gene expression, the EAR2 regulates the renin gene expression in As4.1 cells in a negative way. 19,20 Li et al 21 demonstrated that renin mRNA downregulation by vitamin D in As4.1 cells results from a decrease in the ren1 c promoter activity.…”

Section: Discussionmentioning

confidence: 99%

“…20 Although retinoic acid is responsible for upregulation of renin gene expression, the EAR2 regulates the renin gene expression in As4.1 cells in a negative way. 19,20 Li et al 21 demonstrated that renin mRNA downregulation by vitamin D in As4.1 cells results from a decrease in the ren1 c promoter activity. In addition, Shi et al 19 demonstrated that the transcriptional activity of a construct containing a triple copy of a TGACCT-N 10 -TGACCT motif placed upstream of the renin promoter is repressed by 1.25 dihydroxyvitamin D 3 .…”

Section: Discussionmentioning

confidence: 99%

Calcium Inhibits Renin Gene Expression by Transcriptional and Posttranscriptional Mechanisms

et al. 2005

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Abstract-The aim of this study was to investigate the role of cytosolic calcium for renin gene expression in juxtaglomerular cells. For this purpose, we used the immortalized juxtaglomerular mouse cell line As4.1. To increase cytosolic calcium concentration, we treated the cells with thapsigargin and cyclopiazonic acid, inhibitors of the endoplasmatic reticulum CaϪ ATPase. Thapsigargin and cyclopiazonic acid inhibited renin gene expression in a characteristic time and concentration-dependent manner. This effect was concentration-dependently blocked by BAPTA-AM, an intracellular Ca 2ϩ chelator. Pharmacological blocking of protein kinase C activity by calphostin, Gö6976, and Gö6983 did not change the effect of thapsigargin on renin gene expression. Experiments with renin1 C -promoter-reporter constructs revealed that thapsigargin inhibited renin gene transcription. Analysis of deletion constructs of the renin1 C promoter indicated that regulatory elements involved in the calcium-mediated inhibition of renin gene transcription are located in the enhancer region of the renin gene and that Ն3 transcription factor-binding sites are involved in this process. In addition, thapsigargin reduced the renin mRNA half-life from 10 hours (control conditions) to 4 hours. Knockdown studies with small interfering RNA directed to dynamin-1 mRNA revealed that dynamin-1 is likely to be involved in the calcium-mediated destabilization of renin mRNA. These data suggest that calcium inhibits renin gene expression in juxtaglomerular cells via a concerted action of inhibition of renin gene transcription and destabilization of renin mRNA. Key Words: calcium Ⅲ renin-angiotensin-aldosterone system Ⅲ thapsigargin Ⅲ mRNA stability T he renin-angiotensin-aldosterone system is a major regulatory system controlling extracellular fluid volume and blood pressure. The activity of the renin-angiotensin-aldosterone system is rate limited by the activity of the protease renin. 1 Renin itself is also regulated by a variety of factors. In the past few years, our knowledge has increased substantially about the regulation of renin gene expression at the cellular level. [2][3][4] For the transcription of the mouse renin gene, 2 critical regions, a proximal promoter region at Ϫ197 to Ϫ50 bp and an enhancer element at Ϫ2866 to Ϫ2625 bp, have been identified. 4 Also, the regulation of the renin mRNA stability is influenced by various factors, among these, interacting partner proteins like MINT, dynamin, or nucleolin have been found to be involved in the stabilization process of the renin mRNA. 5 The focus of our study was to investigate the role of calcium in the regulation of renin gene expression. This is of particular interest, because vasoactive peptides like angiotensin II or endothelin-1, which are known to be direct regulators of renin gene expression, activate the phospholipase C via a G protein-coupled receptor and, in turn, increase inositol triphosphate and diacylglycerol (DAG). 3 Whereas DAG is known to activate protein kinase C, inositol triphosp...

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“…12 Proteins were separated on 7.5% SDS-polyacrylamide gel and transferred onto nitrocellulose membranes. Immunoreactive proteins were detected by incubating the blots with diluted p65 rabbit polyclonal antibody at 4°C overnight, followed by horseradish peroxidaseconjugated secondary antibody (Santa Cruz Biotechnology) and visualization with an enhanced chemiluminescence system (NEN).…”

Section: Western Blottingmentioning

confidence: 99%

Ghrelin Inhibits Proinflammatory Responses and Nuclear Factor-κB Activation in Human Endothelial Cells

et al. 2004

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Background-Ghrelin is a novel growth hormone-releasing peptide that has been shown to improve cachexia in heart failure and cancer and to ameliorate the hemodynamic and metabolic disturbances in septic shock. Because cytokine-induced inflammation is critical in these pathological states and because the growth hormone secretagogue receptor has been identified in blood vessels, we examined whether ghrelin inhibits proinflammatory responses in human endothelial cells in vitro and after administration of endotoxin to rats in vivo. Methods and Results-Human umbilical vein endothelial cells (HUVECs) were treated with or without tumor necrosis factor-␣ (TNF-␣), and induction of proinflammatory cytokines and mononuclear cell adhesion were determined. Ghrelin (0.1 to 1000 ng/mL) inhibited both basal and TNF-␣-induced cytokine release and mononuclear cell binding. Intravenous administration of ghrelin also inhibited endotoxin-induced proinflammatory cytokine production in rats in vivo. Ghrelin inhibited H 2 O 2 -induced cytokine release in HUVECs, suggesting that the peptide blocks redox-mediated cellular signaling. Moreover, ghrelin inhibited basal and TNF-␣-induced activation of nuclear factor-B. Des-acyl ghrelin had no effect on TNF-␣-induced cytokine production in HUVECs, suggesting that the antiinflammatory effects of ghrelin require interaction with endothelial growth hormone secretagogue receptors. Conclusions-Ghrelin inhibits proinflammatory cytokine production, mononuclear cell binding, and nuclear factor-B activation in human endothelial cells in vitro and endotoxin-induced cytokine production in vivo. These novel antiinflammatory actions of ghrelin suggest that the peptide could play a modulatory role in atherosclerosis, especially in obese patients, in whom ghrelin levels are reduced.

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Identification of a Nuclear Orphan Receptor (Ear2) as a Negative Regulator of Renin Gene Transcription

Cited by 57 publications

References 54 publications

The Human Renin Kidney Enhancer Is Required to Maintain Base-line Renin Expression but Is Dispensable for Tissue-specific, Cell-specific, and Regulated Expression

The Human Renin Kidney Enhancer Is Required to Maintain Base-line Renin Expression but Is Dispensable for Tissue-specific, Cell-specific, and Regulated Expression

Calcium Inhibits Renin Gene Expression by Transcriptional and Posttranscriptional Mechanisms

Ghrelin Inhibits Proinflammatory Responses and Nuclear Factor-κB Activation in Human Endothelial Cells

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