scholarly journals Glucocorticoid and mineralocorticoid regulation of angiotensin II type 1 receptor binding and inositol triphosphate formation in WB cells

1999 ◽  
Vol 162 (3) ◽  
pp. 381-391 ◽  
Author(s):  
SG Shelat ◽  
LM Flanagan-Cato ◽  
SJ Fluharty
Keyword(s):  
Angiotensin Ii ◽  
Cell Line ◽  
At1 Receptor ◽  
Inositol Triphosphate ◽  
Epithelial Cell Line ◽  
Salt Appetite ◽  
Pressor Responses ◽  
The Brain

Mineralocorticoids, glucocorticoids, and angiotensin II (AngII) act cooperatively to maintain body fluid homeostasis. Mineralocorticoids, such as aldosterone and deoxycorticosterone-acetate (DOCA), function synergistically with AngII in the brain to increase salt appetite and blood pressure. In addition, glucocorticoids increase AngII-induced drinking and pressor responses and may also facilitate the actions of aldosterone on salt appetite. The AngII Type 1 (AT1) receptor mediates many of the physiological and behavioral actions of AngII. This receptor is coupled to the G-protein Gq, which mediates AngII-induced inositol triphosphate (IP3) formation. The WB cell line, a liver epithelial cell line that expresses the AT1 receptor, was used to examine the cellular basis of glucocorticoid and mineralocorticoid regulation of AT1 function. In this study corticosterone and dexamethasone treatments increased the number of AT1 receptors by activating the glucocorticoid receptor (GR). This increase in AT1 binding resulted in enhanced AngII-stimulated IP3 formation. However, only supraphysiological doses of aldosterone or DOCA increased AT1 binding, and this effect also was mediated by GR activation. Furthermore, despite evidence that mineralocorticoids and glucocorticoids function together to increase AngII-stimulated actions in vivo, aldosterone and dexamethasone did not act synergistically to affect AT1 binding, Gq expression, or IP3 formation. These results indicate that GR activation, and the subsequent increases in AT1 binding and in AngII-stimulated IP3 formation, may represent a cellular mechanism underlying the synergy between adrenal steroids and AngII.

scholarly journals Angiotensin II type 1 receptor-associated protein deficiency attenuates sirtuin1 expression in an immortalised human renal proximal tubule cell line

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Takahiro Yamaji ◽  
Akio Yamashita ◽  
Hiromichi Wakui ◽  
Kengo Azushima ◽  
Kazushi Uneda ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Protein Expression ◽  
Proximal Tubule ◽  
Cell Line ◽  
Renal Proximal Tubule ◽  
Sirtuin 1 ◽  
Epithelial Cell Line ◽  
Proximal Tubule Cell ◽  
Deficient Mice

Abstract The proximal tubule is a particularly important site for ageing-related kidney damage. Sirtuin 1 (SIRT1), an NAD+ (nicotinamide adenine dinucleotide)-dependent deacetylase in the proximal tubule, may be involved in renal injury associated with ageing. However, the mechanisms of SIRT1 regulation remain to be elucidated. We recently reported that angiotensin II type 1 receptor (AT1R)-associated protein (ATRAP)-deficient mice displayed age-associated renal function decline and tubulointerstitial fibrosis. Our data showed that SIRT1 protein expression was reduced in ATRAP-deficient mice, although the relationship between ATRAP deficiency and age-associated renal fibrosis is still not fully understood. It is, therefore, necessary to investigate how ATRAP affects SIRT1 protein expression to resolve ageing-associated kidney dysfunction. Here, since ageing studies are inherently lengthy, we used an ex vivo model of the proximal tubule to determine the role of ATRAP in SIRT1 protein expression. We first generated a clonal immortalised human renal proximal tubule epithelial cell line (ciRPTEC) expressing AT1R and ATRAP. Using this cell line, we demonstrated that ATRAP knockdown reduced SIRT1 protein expression in the ciRPTEC but did not alter SIRT1 mRNA expression. Thus, ATRAP likely mediates SIRT1 protein abundance in ciRPTEC.

Electrophysiological Measurements of a Toad Renal Epithelial Cell Line (A6) as an Assay for Predicting Ocular Eye Irritancy

1992 ◽  
Vol 20 (2) ◽  
pp. 218-221
Author(s):  
Henning F. Bjerregaard
Keyword(s):  
Epithelial Cell ◽  
Cell Line ◽  
South African ◽  
Mdck Cells ◽  
Epithelial Cell Line ◽  
Renal Epithelial Cell ◽  
Electrophysiological Measurements ◽  
Renal Epithelial Cell Line ◽  
Darby Canine Kidney

An established epithelial cell line (A6) from a South African clawed toad (Xenopus laevis) kidney was used as a model for the corneal epithelium of the eye in order to determine ocular irritancy. When grown on Millipore filter inserts, A6 cells form a monolayer epithelium of high electrical resistance and generate a trans-epithelial potential difference. These two easily-measured electrophysiological endpoints showed a dose-related decrease after exposure for 24 hours to seven selected chemicals of different ocular irritancy potential. It was demonstrated that both trans-epithelial resistance and potential ranked closely with in vivo eye irritancy data and correlated well (r = 0.96) with loss of trans-epithelial impermeability of Madin-Darby canine kidney (MDCK) cells, detected by use of a fluorescein leakage assay.

scholarly journals Probing the Intracellular Bio-Nano Interface in Different Cell Lines with Gold Nanostars

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1183
Author(s):  
Cecilia Spedalieri ◽  
Gergo Péter Szekeres ◽  
Stephan Werner ◽  
Peter Guttmann ◽  
Janina Kneipp
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Early Stage ◽  
Protein Corona ◽  
Fibroblast Cell ◽  
Ultrastructural Level ◽  
Epithelial Cell Line ◽  
Animal Cells ◽  
Gold Nanostars

Gold nanostars are a versatile plasmonic nanomaterial with many applications in bioanalysis. Their interactions with animal cells of three different cell lines are studied here at the molecular and ultrastructural level at an early stage of endolysosomal processing. Using the gold nanostars themselves as substrate for surface-enhanced Raman scattering, their protein corona and the molecules in the endolysosomal environment were characterized. Localization, morphology, and size of the nanostar aggregates in the endolysosomal compartment of the cells were probed by cryo soft-X-ray nanotomography. The processing of the nanostars by macrophages of cell line J774 differed greatly from that in the fibroblast cell line 3T3 and in the epithelial cell line HCT-116, and the structure and composition of the biomolecular corona was found to resemble that of spherical gold nanoparticles in the same cells. Data obtained with gold nanostars of varied morphology indicate that the biomolecular interactions at the surface in vivo are influenced by the spike length, with increased interaction with hydrophobic groups of proteins and lipids for longer spike lengths, and independent of the cell line. The results will support optimized nanostar synthesis and delivery for sensing, imaging, and theranostics.

Involvement of Runx3 in the basal transcriptional activation of the mouse angiotensin II type 1 receptor-associated protein gene

2011 ◽  
Vol 43 (14) ◽  
pp. 884-894 ◽  
Author(s):  
Miyuki Matsuda ◽  
Kouichi Tamura ◽  
Hiromichi Wakui ◽  
Toru Dejima ◽  
Akinobu Maeda ◽  
...  
Keyword(s):  
Gene Expression ◽  
Angiotensin Ii ◽  
Transcriptional Activation ◽  
At1 Receptor ◽  
Distal Convoluted Tubule ◽  
Luciferase Assay ◽  
Serum Starvation ◽  
Receptor Associated Protein ◽  
Tubule Cells

We previously cloned a molecule that interacts with angiotensin II type 1 (AT1) receptor to exert an inhibitory function on AT1 receptor signaling that we named ATRAP/ Agtrap (for AT1 receptor-associated protein). In the present study we examined the regulation of basal ATRAP gene expression using renal distal convoluted tubule cells. We found that serum starvation upregulated basal expression of ATRAP gene, a response that required de novo mRNA and protein synthesis. Luciferase assay revealed that the proximal promoter region directs transcription and that a putative binding site of runt-related transcription factors (RBE) is important for transcriptional activation. The results of RBE-decoy transfection and endogenous knockdown by small interference RNA showed that the runt-related transcription factor Runx3 is involved in ATRAP gene expression. Chromatin immunoprecipitation assay also supported the binding of Runx3 to the ATRAP promoter in renal distal convoluted tubule cells. Immunohistochemistry demonstrated the expression of Runx3 and ATRAP proteins in the distal convoluted and connecting tubules of the kidney in consecutive sections. Furthermore, the Runx3 immunostaining was decreased together with a concomitant suppression of ATRAP expression in the affected kidney after 7 days of unilateral ureteral obstruction. These findings indicate that Runx3 plays a role in ATRAP gene expression in renal distal tubular cells both in vitro and in vivo.

Infection of epithelial cell line HEp-2 with human immunodeficiency virus type 1 is CD4 dependent

1993 ◽  
Vol 40 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Hans S. L. M. Nottet ◽  
Ingmar Janse ◽  
Loek De Graaf ◽  
Leendert J. Bakker ◽  
Maarten R. Visser ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Epithelial Cell ◽  
Cell Line ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Epithelial Cell Line ◽  
Immunodeficiency Virus

Is it Possible to Differentiate between Angiotensin II Type 1 (AT1) Receptor Blockers in Normotensive Volunteers?

2000 ◽  
Vol 9 (sup1) ◽  
pp. 53-53
Author(s):  
M. AZIZI, ◽  
G. CHATELLIER, ◽  
L. NICOLET, ◽  
T. GUYENE, ◽  
J. HEMPENIUS, ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
At1 Receptor ◽  
Receptor Blockers ◽  
At1 Receptor Blockers

Abstract 56: Candesartan And Valsartan, Contrary To Irbesartan, Are Potent Biased Antagonists Of Adrenal (beta)arrestin-dependent, Angiotensin II Type 1 Receptor-induced Aldosterone Production And Improve Cardiac Function Post-myocardial Infarction

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Anastasios Lymperopoulos ◽  
Karlee Walklett ◽  
Samalia Dabul ◽  
Ashley Siryk ◽  
Emmanuel Sturchler ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Angiotensin Ii ◽  
Cardiac Function ◽  
G Protein ◽  
Plasma Aldosterone ◽  
Post Myocardial Infarction ◽  
Aldosterone Production

Introduction: The scaffolding protein βarrestin1 (βarr1) by the angiotensin II (AngII) type 1 receptor (AT 1 R) mediates AngII-induced aldosterone production in vitro and physiologically in vivo, thereby exacerbating heart failure (HF) progression post-myocardial infarction (MI). Herein, we sought to investigate the relative potency of various AT 1 R antagonist drugs (sartans) at inhibiting βarr vs. G protein activation and hence aldosterone production in vitro and in vivo. We also investigated the alterations in plasma aldosterone levels conferred by these agents and their impact on cardiac function of post-MI rats. Methods: For the in vitro tests, transfected CHO and adrenocortical H295R cells were used. For in vivo studies, post-MI rats overexpressing βarr1 in their adrenals received 7-day-long treatments with the drugs of interest. Results: Among the sartans tested, candesartan and valsartan were the most potent βarr activation and βarr-mediated aldosterone production inhibitors in vitro, as well as the most “biased” antagonists towards βarr vs. G-protein inhibition. Conversely, losartan and irbesartan were the least potent βarr inhibitors and the least “biased” antagonists towards βarr inhibition. These in vitro findings were corroborated in vivo, since candesartan and valsartan, contrary to irbesartan, caused significant plasma aldosterone reductions in post-MI rats. Accordingly, cardiac ejection fraction (EF) and contractility were significantly augmented in candesartan- and valsartan-treated rats (EF: 41.1±1% and 40±1% respectively, vs. 35±0.3% for saline-treated), but further deteriorated in irbesartan-treated post-MI rats (EF: 32±1%, n=7 rats/group). Conclusions: These findings provide important insights that might aid pharmacotherapeutic decisions (i.e. individual agent selections) involving this commonly prescribed cardiovascular drug class (sartans).

scholarly journals Synthesis and Evaluation of [18F]FEtLos and [18F]AMBF3Los as Novel 18F-Labelled Losartan Derivatives for Molecular Imaging of Angiotensin II Type 1 Receptors

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1872
Author(s):  
Martha Sahylí Ortega Pijeira ◽  
Paulo Sérgio Gonçalves Nunes ◽  
Sofia Nascimento dos Santos ◽  
Zhengxing Zhang ◽  
Arian Pérez Nario ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Binding Affinity ◽  
Renin Angiotensin System ◽  
Prosthetic Group ◽  
Positron Emission ◽  
One Step ◽  
Group 2

Losartan is widely used in clinics to treat cardiovascular related diseases by selectively blocking the angiotensin II type 1 receptors (AT1Rs), which regulate the renin-angiotensin system (RAS). Therefore, monitoring the physiological and pathological biodistribution of AT1R using positron emission tomography (PET) might be a valuable tool to assess the functionality of RAS. Herein, we describe the synthesis and characterization of two novel losartan derivatives PET tracers, [18F]fluoroethyl-losartan ([18F]FEtLos) and [18F]ammoniomethyltrifluoroborate-losartan ([18F]AMBF3Los). [18F]FEtLos was radiolabeled by 18F-fluoroalkylation of losartan potassium using the prosthetic group 2-[18F]fluoroethyl tosylate; whereas [18F]AMBF3Los was prepared following an one-step 18F-19F isotopic exchange reaction, in an overall yield of 2.7 ± 0.9% and 11 ± 4%, respectively, with high radiochemical purity (>95%). Binding competition assays in AT1R-expressing membranes showed that AMBF3Los presented an almost equivalent binding affinity (Ki 7.9 nM) as the cold reference Losartan (Ki 1.5 nM), unlike FEtLos (Ki 2000 nM). In vitro and in vivo assays showed that [18F]AMBF3Los displayed a good binding affinity for AT1R-overexpressing CHO cells and was able to specifically bind to renal AT1R. Hence, our data demonstrate [18F]AMBF3Los as a new tool for PET imaging of AT1R with possible applications for the diagnosis of cardiovascular, inflammatory and cancer diseases.

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