scholarly journals The Calcium-Sensing Receptor Increases Activity of the Renal NCC through the WNK4-SPAK Pathway

2018 ◽  
Vol 29 (7) ◽  
pp. 1838-1848 ◽  
Author(s):  
Silvana Bazúa-Valenti ◽  
Lorena Rojas-Vega ◽  
María Castañeda-Bueno ◽  
Jonatan Barrera-Chimal ◽  
Rocío Bautista ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Oral Administration ◽  
Apical Membrane ◽  
Hek293 Cells ◽  
Thick Ascending Limb ◽  
Dependent Manner ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing

Background Hypercalciuria can result from activation of the basolateral calcium-sensing receptor (CaSR), which in the thick ascending limb of Henle’s loop controls Ca2+ excretion and NaCl reabsorption in response to extracellular Ca2+. However, the function of CaSR in the regulation of NaCl reabsorption in the distal convoluted tubule (DCT) is unknown. We hypothesized that CaSR in this location is involved in activating the thiazide-sensitive NaCl cotransporter (NCC) to prevent NaCl loss.Methods We used a combination of in vitro and in vivo models to examine the effects of CaSR on NCC activity. Because the KLHL3-WNK4-SPAK pathway is involved in regulating NaCl reabsorption in the DCT, we assessed the involvement of this pathway as well.Results Thiazide-sensitive 22Na+ uptake assays in Xenopus laevis oocytes revealed that NCC activity increased in a WNK4-dependent manner upon activation of CaSR with Gd3+. In HEK293 cells, treatment with the calcimimetic R-568 stimulated SPAK phosphorylation only in the presence of WNK4. The WNK4 inhibitor WNK463 also prevented this effect. Furthermore, CaSR activation in HEK293 cells led to phosphorylation of KLHL3 and WNK4 and increased WNK4 abundance and activity. Finally, acute oral administration of R-568 in mice led to the phosphorylation of NCC.Conclusions Activation of CaSR can increase NCC activity via the WNK4-SPAK pathway. It is possible that activation of CaSR by Ca2+ in the apical membrane of the DCT increases NaCl reabsorption by NCC, with the consequent, well known decrease of Ca2+ reabsorption, further promoting hypercalciuria.

Peptide Blocking Self-Polymerization of Extracellular Calcium-Sensing Receptor Attenuates Hypoxia-Induced Pulmonary Hypertension

Hypertension ◽  
2021 ◽  
Author(s):  
Rui Xiao ◽  
Shengquan Luo ◽  
Ting Zhang ◽  
Yankai Lv ◽  
Tao Wang ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Disulfide Bonds ◽  
Acute Hypoxia ◽  
Extracellular Domain ◽  
Left Ventricular ◽  
Extracellular Calcium ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing

Activation of the CaSR (extracellular calcium-sensing receptor) has been recognized as a critical mediator of hypoxia-induced pulmonary hypertension. Preventive targeting of the early initiating phase as well as downstream events after CaSR activation remains unexplored. As a representative of the G protein-coupled receptor family, CaSR polymerizes on cell surface upon stimulation. Immunoblotting together with MAL-PEG technique identified a reactive oxygen species-sensitive CaSR polymerization through its extracellular domain in pulmonary artery smooth muscle cells upon exposure to acute hypoxia. Fluorescence resonance energy transfer screening employing blocking peptides determined that cycteine129/131 residues in the extracellular domain of CaSR formed intermolecular disulfide bonds to promote CaSR polymerization. The monitoring of intracellular Ca 2+ signal highlighted the pivotal role of CaSR polymerization in its activation. In contrast, the blockade of disulfide bonds formation using a peptide decreased both CaSR and hypoxia-induced mitogenic factor expression as well as other hypoxic-related genes in vitro and in vivo and attenuated pulmonary hypertension development in rats. The blocking peptide did not affect systemic arterial oxygenation in vivo but inhibited acute hypoxia-induced pulmonary vasoconstriction. Pharmacokinetic analyses revealed a more efficient lung delivery of peptide by inhaled nebulizer compared to intravenous injection. In addition, the blocking peptide did not affect systemic arterial pressure, body weight, left ventricular function, liver, or kidney function or plasma Ca 2+ level. In conclusion, a peptide blocking CaSR polymerization reduces its hypoxia-induced activation and downstream events leading to pulmonary hypertension and represents an attractive inhaled preventive alternative worthy of further development.

SCFA increase intestinal Na absorption by induction of NHE3 in rat colon and human intestinal C2/bbe cells

2001 ◽  
Vol 280 (4) ◽  
pp. G687-G693 ◽  
Author(s):  
Mark W. Musch ◽  
Cres Bookstein ◽  
Yue Xie ◽  
Joseph H. Sellin ◽  
Eugene B. Chang
Keyword(s):  
Brush Border ◽  
Apical Membrane ◽  
Bacterial Flora ◽  
Short Chain Fatty Acids ◽  
Rat Colon ◽  
Dependent Manner ◽  
Soluble Fiber ◽  
Concentration Dependent Manner

Short-chain fatty acids (SCFA), produced by colonic bacterial flora fermentation of dietary carbohydrates, promote colonic Na absorption through mechanisms not well understood. We hypothesized that SCFA promote increased expression of apical membrane Na/H exchange (NHE), serving as luminal physiological cues for regulating colonic Na absorptive capacity. Studies were performed in human colonic C2/bbe (C2) monolayers and in vivo. In C2 cells exposed to butyrate, acetate, proprionate, or the poorly metabolized SCFA isobutyrate, apical membrane NHE3 activity and protein expression increased in a time- and concentration-dependent manner, whereas no changes were observed for NHE2. In contrast, no significant changes in brush-border hydrolase or villin expression were noted. Analogous to the in vitro findings, rats fed the soluble fiber pectin exhibited a time-dependent increase in colonic NHE3, but not NHE2, protein, mRNA, and brush-border activity. These changes were region-specific, as no changes were observed in the ileum. We conclude that luminal SCFA are important physiological cues for regulating colonic Na absorptive function, allowing the colon to adapt to chronic changes in dietary carbohydrate and Na loads.

The human renin infused rat: use as an in vivo model for the biological evaluation of human renin inhibitors

1999 ◽  
Vol 77 (11) ◽  
pp. 886-895 ◽  
Author(s):  
Gordon Bolger ◽  
Jean-Claude Vigeant ◽  
Francine Liard ◽  
Bruno Simoneau ◽  
Diane Thibeault ◽  
...  
Keyword(s):  
Oral Administration ◽  
Pressor Response ◽  
Biological Evaluation ◽  
In Vivo Model ◽  
Dependent Manner ◽  
Renin Inhibitors ◽  
Human Renin ◽  
Dose Dependent

The human renin infused rat model (HRIRM) was used as an in vivo small-animal model for evaluating the efficacy of a collection of inhibitors of human renin. The intravenous infusion of recombinant human renin (2.4 µg·kg-1·min-1) in the ganglion-blocked, nephrectomized rat produced a mean blood pressor response of 47 ± 3 mmHg (1 mmHg = 133.3 Pa), which was reduced by captopril, enalkiren, and losartan in a dose-dependent manner following oral administration, with ED50 values of 0.3 ± 0.1, 2.5 ± 0.9, and 5.2 ± 1.6 mg/kg, respectively. A series of peptidomimetic P2-P3 butanediamide renin inhibitors inhibited purified recombinant human renin in vitro in a concentration-dependent manner, with IC50 values ranging from 0.4 to 20 nM at pH 6.0, with a higher range of IC50 values (0.8-80 nM) observed at pH 7.4. Following i.v. administration of renin inhibitors, the pressor response to infused human renin in the HRIRM was inhibited in a dose-dependent manner, with ED50 values ranging from 4 to 600 µg/kg. The in vivo inhibition of human renin following i.v. administration in the rat correlated significantly better with the in vitro inhibition of human renin at pH 7.4 (r = 0.8) compared with pH 6.0 (r = 0.5). Oral administration of renin inhibitors also resulted in a dose-dependent inhibition of the pressor response to infused human renin, with ED50 values ranging from 0.4 to 6.0 mg/kg and the identification of six renin inhibitors with an oral potency of <1 mg/kg. The ED50 of renin inhibitors for inhibition of angiotensin I formation in vivo was highly correlated (r = 0.9) with the ED50 for inhibition of the pressor response. These results demonstrate the high potency, dose dependence, and availability following oral administration of the butanediamide series of renin inhibitors.Key words: renin-angiotensin system, recombinant human renin, rat, renin inhibitors.

scholarly journals Persimmon-derived tannin has antiviral effects and reduces the severity of infection and transmission of SARS-CoV-2 in a Syrian hamster model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryutaro Furukawa ◽  
Masahiro Kitabatake ◽  
Noriko Ouji-Sageshima ◽  
Yuki Suzuki ◽  
Akiyo Nakano ◽  
...  
Keyword(s):  
Oral Administration ◽  
Syrian Hamster ◽  
Carboxymethyl Cellulose ◽  
Plaque Assay ◽  
Control Group ◽  
Dependent Manner ◽  
Hamster Model ◽  
Antiviral Effects

AbstractCoronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread across the world. Inactivating the virus in saliva and the oral cavity represents a reasonable approach to prevent human-to-human transmission because the virus is easily transmitted through oral routes by dispersed saliva. Persimmon-derived tannin is a condensed type of tannin that has strong antioxidant and antimicrobial activity. In this study, we investigated the antiviral effects of persimmon-derived tannin against SARS-CoV-2 in both in vitro and in vivo models. We found that persimmon-derived tannin suppressed SARS-CoV-2 titers measured by plaque assay in vitro in a dose- and time-dependent manner. We then created a Syrian hamster model by inoculating SARS-CoV-2 into hamsters’ mouths. Oral administration of persimmon-derived tannin dissolved in carboxymethyl cellulose before virus inoculation dramatically reduced the severity of pneumonia with lower virus titers compared with a control group inoculated with carboxymethyl cellulose alone. In addition, pre-administration of tannin to uninfected hamsters reduced hamster-to-hamster transmission of SARS-CoV-2 from a cohoused, infected donor cage mate. These data suggest that oral administration of persimmon-derived tannin may help reduce the severity of SARS-CoV-2 infection and transmission of the virus.

Abstract 16791: Oral Administration of Synthetic Prostacyclin Agonist Ono-1301 Prevents Deterioration of Cardiac Performance by Preserving Cardiac Structural Proteins in the Delta-sarcoglycan-deficient Hamster: Promising Treatment for Patients With DCM

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Shigeru Miyagawa ◽  
Yoshiki Sakai ◽  
Satsuki Fukushima ◽  
Shigeo Masuda ◽  
Atsuhiro Saito ◽  
...  
Keyword(s):  
Basement Membrane ◽  
Oral Administration ◽  
Systolic Function ◽  
Cardiac Performance ◽  
Structural Proteins ◽  
Control Group ◽  
Dependent Manner ◽  
Significant Deterioration

Background: Although drugs such as beta blockers are reported to be effective for dilated cardiomyopathy (DCM), they are only effective in selected patients, and new therapeutics based on different mechanisms are still needed. We hypothesized that synthetic prostacyclin agonist (ONO-1301) would preserve the structural proteins in distressed cardiomyocytes, thus attenuating the deterioration of cardiac performance in the delta sarcoglycan-deficient hamster. Methods and Results: In an in vitro study, ONO-1301 was added to the culture medium of non-myocyte cells and the expression of several cytokines including VEGF was examined by ELISA. For the in vivo study, ONO-1301 (A: 3, n=5, B: 1, n=6, C: 0.3, n=7, D: 0.1 mg/kg/dose, n=7) was orally administered to delta-sarcoglycan-deficient hamsters every day from 8 to 20 weeks after birth. The control group (n=6) was untreated. Functional performance was evaluated by US before, 2, 4, 6, and 8 weeks after administration of ONO-1301. A histological analysis focusing on basement-membrane structural proteins, such as α-sarcoglycan, β-sarcoglycan, and α-dystroglycan, fibrosis, and hypertrophy was performed. In vitro, ONO-1301 enhanced the cytokine expressions dose dependently. In vivo, systolic function (EF) was gradually increased in the ONO-1301-treated groups, while it showed significant deterioration in the control group (45.7±2.9, 42.0±2.6, 32.3±1.0, 30.3±2.5, 26.3±2.7%, in groups A, B, C, D, and control, respectively, P<0.05). ONO-1301 also significantly attenuated the LV dilatation in a dose-dependent manner. Immunostaining revealed that all the cardiac structural proteins were preserved in the basement membrane of cardiomyocytes in the 3.0 mg/kg ONO-1301 treatment group, while they disappeared in the control. The % fibrosis and cell hypertrophy were significantly attenuated in the ONO-1301-treated group compared with the control. Conclusions: Oral administration of synthetic prostacyclin agonists, which can enhance cytokine expressions in non-myocyte cells, may preserve cardiac structural proteins in the delta sarcoglycan-deficient hamster, to maintain cardiac performance. This promising drug may inhibit the progression of the disease pathology in DCM, prolonging their life.

Gentamicin Inhibits Ca2+ Channel TPRV5 and Induces Calciuresis Independent of the Calcium-Sensing Receptor-Claudin-14 Pathway

2022 ◽  
pp. ASN.2021030392
Author(s):  
Wouter van Megen ◽  
Megan Beggs ◽  
Sung-Wan An ◽  
Patrícia Ferreira ◽  
Justin Lee ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Hek293 Cells ◽  
Luciferase Reporter ◽  
Thick Ascending Limb ◽  
Wild Type ◽  
Distal Nephron ◽  
Proximal Tubular ◽  
Claudin 14

Background Treatment with the aminoglycoside antibiotic gentamicin can be associated with severe adverse effects, including renal calcium wasting. The underlying mechanism is unknown but it has been proposed to involve activation of the Ca2+-sensing receptor (CaSR) in the thick ascending limb, which would increase expression of claudin-14 (CLDN14) and limit Ca2+ reabsorption. However, no direct evidence for this hypothesis has been presented. Methods We studied the effect of gentamicin in vivo using mouse models with impaired Ca2+ reabsorption in the proximal tubule and the thick ascending limb. We used a Cldn14 promoter luciferase-reporter assay to study CaSR activation and investigated the effect of gentamicin on activity of the distal nephron Ca2+ channel transient potential receptor vanilloid 5 (TPRV5), as determined by patch-clamp in HEK293 cells. Results Gentamicin increased urinary Ca2+ excretion in wild-type mice following acute and chronic administration. This calciuretic effect was unaltered in mice with genetic CaSR overactivation and was present in furosemide-treated animals, whereas the calciuretic effect in Cldn14-/-mice and mice with impaired proximal tubular Ca2+ reabsorption (claudin-2 [CLDN2]-deficient Cldn2-/- mice) was equivalent to that of wild-type mice. In vitro, gentamicin failed to activate the CaSR. In contrast, patch-clamp analysis revealed that gentamicin strongly inhibited rabbit and human TRPV5 activity and that chronic gentamicin administration downregulated distal nephron Ca2+ transporters. Conclusions Gentamicin does not cause hypercalciuria via activation of the CaSR-CLDN14 pathway or by interfering with proximal tubular CLDN2-dependent Ca2+ reabsorption. Instead, gentamicin blocks distal Ca2+ reabsorption by direct inhibition of the Ca2+ channel TRPV5. These findings offer new insights into calcium wasting in patients treated with gentamicin.

scholarly journals Calcium-Sensing Receptor and Aquaporin 2 Interplay in Hypercalciuria-Associated Renal Concentrating Defect in Humans. An In Vivo and In Vitro Study

PLoS ONE ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. e33145 ◽  
Author(s):  
Giuseppe Procino ◽  
Lisa Mastrofrancesco ◽  
Grazia Tamma ◽  
Domenica Rita Lasorsa ◽  
Marianna Ranieri ◽  
...  
Keyword(s):  
In Vitro Study ◽  
Vitro Study ◽  
Calcium Sensing Receptor ◽  
Aquaporin 2 ◽  
Calcium Sensing ◽  
Concentrating Defect

scholarly journals The Calcilytic Agent NPS 2143 Rectifies Hypocalcemia in a Mouse Model With an Activating Calcium-Sensing Receptor (CaSR) Mutation: Relevance to Autosomal Dominant Hypocalcemia Type 1 (ADH1)

Endocrinology ◽  
2015 ◽  
Vol 156 (9) ◽  
pp. 3114-3121 ◽  
Author(s):  
Fadil M. Hannan ◽  
Gerard V. Walls ◽  
Valerie N. Babinsky ◽  
M. Andrew Nesbit ◽  
Enikö Kallay ◽  
...  
Keyword(s):  
Mouse Model ◽  
Urinary Calcium ◽  
Hek293 Cells ◽  
Calcium Excretion ◽  
Wild Type ◽  
Calcium Sensing Receptor ◽  
Gain Of Function ◽  
Calcium Sensing

Autosomal dominant hypocalcemia type 1 (ADH1) is caused by germline gain-of-function mutations of the calcium-sensing receptor (CaSR) and may lead to symptomatic hypocalcemia, inappropriately low serum PTH concentrations and hypercalciuria. Negative allosteric CaSR modulators, known as calcilytics, have been shown to normalize the gain-of-function associated with ADH-causing CaSR mutations in vitro and represent a potential targeted therapy for ADH1. However, the effectiveness of calcilytic drugs for the treatment of ADH1-associated hypocalcemia remains to be established. We have investigated NPS 2143, a calcilytic compound, for the treatment of ADH1 by in vitro and in vivo studies involving a mouse model, known as Nuf, which harbors a gain-of-function CaSR mutation, Leu723Gln. Wild-type (Leu723) and Nuf mutant (Gln723) CaSRs were expressed in HEK293 cells, and the effect of NPS 2143 on their intracellular calcium responses was determined by flow cytometry. NPS 2143 was also administered as a single ip bolus to wild-type and Nuf mice and plasma concentrations of calcium and PTH, and urinary calcium excretion measured. In vitro administration of NPS 2143 decreased the intracellular calcium responses of HEK293 cells expressing the mutant Gln723 CaSR in a dose-dependent manner, thereby rectifying the gain-of-function associated with the Nuf mouse CaSR mutation. Intraperitoneal injection of NPS 2143 in Nuf mice led to significant increases in plasma calcium and PTH without elevating urinary calcium excretion. These studies of a mouse model with an activating CaSR mutation demonstrate NPS 2143 to normalize the gain-of-function causing ADH1 and improve the hypocalcemia associated with this disorder.

NFAT regulates calcium-sensing receptor-mediated TNF production

2006 ◽  
Vol 290 (5) ◽  
pp. F1110-F1117 ◽  
Author(s):  
Huda Ismail Abdullah ◽  
Paulina L. Pedraza ◽  
Shoujin Hao ◽  
Karin D. Rodland ◽  
John C. McGiff ◽  
...  
Keyword(s):  
Extracellular Fluid ◽  
Dominant Negative ◽  
Peptide Ligand ◽  
Thick Ascending Limb ◽  
Dependent Manner ◽  
Calcium Sensing Receptor ◽  
Activated T Cells ◽  
Calcium Sensing ◽  
Dependent Activity ◽  
Calcineurin Activity

Because nuclear factor of activated T cells (NFAT) has been implicated in TNF production as well as osmoregulation and salt and water homeostasis, we addressed whether calcium-sensing receptor (CaR)-mediated TNF production in medullary thick ascending limb (mTAL) cells was NFAT dependent. TNF production in response to addition of extracellular Ca2+ (1.2 mM) was abolished in mTAL cells transiently transfected with a dominant-negative CaR construct (R796W) or pretreated with the phosphatidylinositol phospholipase C (PI-PLC) inhibitor U-73122. Cyclosporine A (CsA), an inhibitor of the serine/threonine phosphatase calcineurin, and a peptide ligand, VIVIT, that selectively inhibits calcineurin-NFAT signaling, also prevented CaR-mediated TNF production. Increases in calcineurin activity in cells challenged with Ca2+ were inhibited after pretreatment with U-73122 and CsA, suggesting that CaR activation increases calcineurin activity in a PI-PLC-dependent manner. Moreover, U-73122, CsA, and VIVIT inhibited CaR-dependent activity of an NFAT construct that drives expression of firefly luciferase in transiently transfected mTAL cells. Collectively, these data verify the role of calcineurin and NFAT in CaR-mediated TNF production by mTAL cells. Activation of the CaR also increased the binding of NFAT to a consensus oligonucleotide, an effect that was blocked by U-73122 and CsA, suggesting that a calcineurin- and NFAT-dependent pathway increases TNF production in mTAL cells. This mechanism likely regulates TNF gene transcription as U-73122, CsA, and VIVIT blocked CaR-dependent activity of a TNF promoter construct. Elucidating CaR-mediated signaling pathways that regulate TNF production in the mTAL will be crucial to understanding mechanisms that regulate extracellular fluid volume and salt balance.

scholarly journals Kokumi taste perception is functional in a model carnivore, the domestic cat (Felis catus)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A. Laffitte ◽  
M. Gibbs ◽  
C. Hernangomez de Alvaro ◽  
J. Addison ◽  
Z. N. Lonsdale ◽  
...  
Keyword(s):  
Amino Acids ◽  
Taste Receptor ◽  
Felis Catus ◽  
Domestic Cat ◽  
Taste Perception ◽  
Ligand Specificity ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing

AbstractKokumi taste is a well-accepted and characterised taste modality and is described as a sensation of enhancement of sweet, salty, and umami tastes. The Calcium Sensing Receptor (CaSR) has been designated as the putative kokumi taste receptor for humans, and a number of kokumi-active ligands of CaSR have been discovered recently with activity confirmed both in vivo and in vitro. Domestic cats (Felis catus) are obligate carnivores and accordingly, their diet is abundant in proteins, peptides, and amino acids. We hypothesised that CaSR is a key taste receptor for carnivores, due to its role in the detection of different peptides and amino acids in other species. Using in silico, in vitro and in vivo approaches, here we compare human CaSR to that of a model carnivore, the domestic cat. We found broad similarities in ligand specificity, but differences in taste sensitivity between the two species. Indeed our in vivo data shows that cats are sensitive to CaCl2 as a kokumi compound, but don’t show this same activity with Glutathione, whereas for humans the reverse is true. Collectively, our data suggest that kokumi is an important taste modality for carnivores that drives the palatability of meat-derived compounds such as amino acids and peptides, and that there are differences in the perception of kokumi taste between carnivores and omnivores.

Sign in / Sign up

Export Citation Format

Share Document