Augmented extracellular ATP signaling in bladder urothelial cells from patients with interstitial cystitis

2006 ◽  
Vol 290 (1) ◽  
pp. C27-C34 ◽  
Author(s):  
Yan Sun ◽  
Toby C. Chai
Keyword(s):  
Interstitial Cystitis ◽  
Purinergic Signaling ◽  
Atp Release ◽  
Extracellular Atp ◽  
Luciferase Assay ◽  
Heparin Binding ◽  
Urothelial Cells ◽  
Atp Levels ◽  
And Control ◽  
Atp Signaling

Interstitial cystitis (IC) is an idiopathic hypersensory condition of the bladder associated with increased urinary ATP and increased stretch-activated ATP release by bladder urothelial cells (BUCs), suggesting augmented purinergic signaling in the bladder. To test this theory further, monolayers of cultured BUCs derived from bladder biopsies obtained from patients with IC and control patients were stimulated with 10–30 μM ATP with subsequent measurement of extracellular ATP levels using the luciferin-luciferase assay. Stimulation with 30 μM ATP resulted in IC supernatant containing several-fold more ATP than control BUCs initially, followed by a slower decrease in ATP levels. This difference in ATP levels was not completely due to activity of cellular ecto-ATPase, because blockade with ARL67156 did not normalize the difference. Exposure to hypotonic solutions resulted in similar extracellular ATP concentrations in IC and control BUCs, but there was a slower decrease in ATP levels in IC supernatants. Treatment of IC BUCs with 10–40 μM suramin, a nonspecific P2 receptor antagonist, significantly attenuated the IC BUC response to extracellular ATP, restoring IC BUCs to a control phenotype. Pretreatment of IC BUCs with 20 ng/ml of heparin-binding EGF-like growth factor (HB-EGF), which previously has been shown to be decreased in IC urine specimens, also restored IC BUCs to a control phenotype with respect to response to ATP stimulation. In conclusion, IC BUCs have augmented extracellular ATP signaling that could be blocked by suramin and HB-EGF. These findings suggest the possible development of future novel therapeutic techniques.

EGF and HB-EGF modulate inward potassium current in human bladder urothelial cells from normal and interstitial cystitis patients

2007 ◽  
Vol 292 (1) ◽  
pp. C106-C114 ◽  
Author(s):  
Yan Sun ◽  
Mingkui Chen ◽  
Benjamin H. Lowentritt ◽  
P. Sean Van Zijl ◽  
Kristopher R. Koch ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Interstitial Cystitis ◽  
Potassium Current ◽  
Purinergic Signaling ◽  
Potassium Conductance ◽  
Heparin Binding ◽  
Urothelial Cells ◽  
Epidermal Growth ◽  
Dose Dependent Decrease

Interstitial cystitis (IC) is an idiopathic condition characterized by bladder hyperalgesia. Studies have shown cytokine and purinergic signaling abnormalities in cultured bladder urothelial cells (BUC) from IC patients. We performed single-cell electrophysiological studies in both normal and IC BUC. A strongly inward rectifying potassium current with conductance of the Kir2.1 channel was identified in normal BUC. This current was significantly reduced in IC BUC. Kir2.1 protein and mRNA were detected in both IC and normal BUC. Epidermal growth factor (EGF) caused a dose-dependent decrease in the inward potassium current in normal BUC. EGF is secreted in higher amounts by IC BUC and is known to decrease Kir2.1 conductance by phosphorylation of Kir2.1. Genistein, a nonspecific phosphorylation inhibitor, increased the inward potassium current in IC BUC and blocked the effect of EGF on normal BUC. Treatment of IC BUC with heparin-binding epidermal growth factor-like growth factor (HB-EGF), previously shown to be secreted in lower amounts by IC BUC, significantly increased inward potassium current. These data show that the inward potassium current in BUC can be modulated by EGF and HB-EGF. Changes in BUC membrane potassium conductance caused by altered levels of EGF and HB-EGF may therefore play a role in the pathophysiology of IC.

Differentiation Associated Changes in Gene Expression Profiles of Interstitial Cystitis and Control Urothelial Cells

2008 ◽  
Vol 180 (6) ◽  
pp. 2681-2687 ◽  
Author(s):  
Deborah R. Erickson ◽  
Steven R. Schwarze ◽  
Justin K. Dixon ◽  
Curtis J. Clark ◽  
Matt A. Hersh
Keyword(s):  
Gene Expression ◽  
Interstitial Cystitis ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Urothelial Cells ◽  
And Control

scholarly journals Pannexin-1 mediated ATP release in adipocytes is sensitive to glucose and insulin and modulates lipolysis and macrophage migration

2018 ◽  
Author(s):  
Marco Tozzi ◽  
Jacob B. Hansen ◽  
Ivana Novak
Keyword(s):  
Adipose Tissue ◽  
Purinergic Receptors ◽  
Purinergic Signaling ◽  
Cell Metabolism ◽  
Atp Release ◽  
Extracellular Atp ◽  
Adrenergic Stimulation ◽  
Pannexin 1 ◽  
White Adipocytes ◽  
Obesity And Diabetes

One-sentence summaryInsulin inhibits ATP release in adipocytesAbstractExtracellular ATP signaling is involved in many physiological and pathophysiological processes, and purinergic receptors are targets for drug therapy in several diseases, including obesity and diabetes. Adipose tissue has crucial functions in lipid and glucose metabolism and adipocytes express purinergic receptors. However, the sources of extracellular ATP in adipose tissue are not yet characterized.Here, we show that upon adrenergic stimulation white adipocytes release ATP through the pannexin-1 pore that is regulated by a cAMP-PKA dependent pathway. The ATP release correlates with increased cell metabolism, and extracellular ATP induces Ca2+ signaling and lipolysis in adipocytes and promotes macrophages migration. Most importantly, ATP release is markedly inhibited by insulin, and thereby auto/paracrine purinergic signaling in adipose tissue would be attenuated. Furthermore, we define the signaling pathway for insulin regulated ATP release.Our findings reveal the insulin-pannexin-1-purinergic signaling cross-talk in adipose tissue and we propose that deregulation of this signaling may underlie adipose tissue inflammation and type-2 diabetes.

Blocking ATP releasing channels prevents high extracellular ATP levels and airway hyperreactivity in an asthmatic mouse model

2021 ◽  
Author(s):  
Llilian Arzola Martínez ◽  
Rebeca Benavente ◽  
Génesis Vega ◽  
Mariana Ríos ◽  
Wendy Fonseca ◽  
...  
Keyword(s):  
Mouse Model ◽  
Airway Inflammation ◽  
Airway Epithelium ◽  
Atp Release ◽  
Specific Inhibitor ◽  
Extracellular Atp ◽  
Airway Hyperreactivity ◽  
Luciferase Assay ◽  
Asthmatic Patients ◽  
Allergic Mouse

Allergic asthma is a chronic airway inflammatory response to different triggers like inhaled allergens. Excessive ATP in fluids from asthmatic patients is considered an inflammatory signal and an important autocrine/paracrine modulator of airway physiology. Here we investigated the deleterious effect of increased extracellular ATP (eATP) concentration on the mucociliary clearance (MCC) effectiveness and determined the role of ATP releasing channels during airway inflammation in an ovalbumin (OVA)-sensitized mouse model. Our allergic mouse model exhibited high levels of eATP measured in the tracheal fluid with a luciferin-luciferase assay and reduced MCC velocity determined by microspheres tracking in the trachea ex vivo. Addition of ATP had a dual effect on MCC, where lower ATP concentration (µM) increased microspheres velocity, while higher concentration (mM) transiently stopped microspheres movement. Also, an augmented ethidium bromide uptake by the allergic tracheal airway epithelium suggests an increase in ATP release channel functionality during inflammatory conditions. The use of carbenoxolone, a non-specific inhibitor of connexin and pannexin1channels reduced the eATP concentration in the allergic mouse tracheal fluid and dye uptake by the airway epithelium, providing evidence that these ATP release channels are facilitating the net flux of ATP to the lumen during airway inflammation. However, only the specific inhibition of pannexin1 with 10Panx peptide significantly reduced eATP in bronchoalveolar lavage and decreased airway hyperresponsiveness in OVA-allergic mouse model. These data provide evidence that blocking eATP may be a pharmacological alternative to be explored in rescue therapy during episodes of airflow restriction in asthmatic patients.

scholarly journals Polarized ATP distribution in urothelial mucosal and serosal space is differentially regulated by stretch and ectonucleotidases

2015 ◽  
Vol 309 (10) ◽  
pp. F864-F872 ◽  
Author(s):  
Weiqun Yu
Keyword(s):  
Purinergic Signaling ◽  
Atp Release ◽  
Mechanical Stretch ◽  
Mechanical Force ◽  
Bladder Function ◽  
Immunofluorescent Localization ◽  
Major Pathway ◽  
Ussing Chambers ◽  
Atp Concentration ◽  
Atp Signaling

Purinergic signaling is a major pathway in regulating bladder function, and mechanical force stimulates urothelial ATP release, which plays an important role in bladder mechanotransduction. Although urothelial ATP release was first reported almost 20 years ago, the way in which release is regulated by mechanical force, and the presence of ATP-converting enzymes in regulating the availability of released ATP is still not well understood. Using a set of custom-designed Ussing chambers with the ability to manipulate mechanical forces applied on the urothelial tissue, we have demonstrated that it is stretch and not hydrostatic pressure that induces urothelial ATP release. The experiments reveal that urothelial ATP release is tightly controlled by stretch speed, magnitude, and direction. We have further shown that stretch-induced urothelial ATP release is insensitive to temperature (4°C). Interestingly, stretch-induced ATP release shows polarized distribution, with the ATP concentration in mucosal chamber (nanomolar level) about 10 times higher than the ATP concentration in serosal chamber (subnanomolar level). Furthermore, we have consistently observed differential ATP lifetime kinetics in the mucosal and serosal chambers, which is consistent with our immunofluorescent localization data, showing that ATP-converting enzymes ENTPD3 and alkaline phosphatase are expressed on urothelial basal surface, but not on the apical membrane. In summary, our data indicate that urothelial ATP release is finely regulated by stretch speed, magnitude, and direction, and extracellular ATP signaling is likely to be differentially regulated by ectonucleotidase, which results in temporally and spatially distinct ATP kinetics in response to mechanical stretch.

Endogenous ATP release regulates Cl− secretion in cultured human and rat biliary epithelial cells

1999 ◽  
Vol 276 (6) ◽  
pp. G1391-G1400 ◽  
Author(s):  
Richard M. Roman ◽  
Andrew P. Feranchak ◽  
Kelli D. Salter ◽  
Yu Wang ◽  
J. Gregory Fitz
Keyword(s):  
Epithelial Cells ◽  
Cell Volume ◽  
Purinergic Signaling ◽  
Cell Volume Regulation ◽  
Atp Release ◽  
Extracellular Atp ◽  
Extracellular Nucleotides ◽  
Cell Swelling ◽  
Biliary Epithelial Cells ◽  
Normal Rat

P2Y receptor stimulation increases membrane Cl− permeability in biliary epithelial cells, but the source of extracellular nucleotides and physiological relevance of purinergic signaling to biliary secretion are unknown. Our objectives were to determine whether biliary cells release ATP under physiological conditions and whether extracellular ATP contributes to cell volume regulation and transepithelial secretion. With the use of a sensitive bioluminescence assay, constitutive ATP release was detected from human Mz-ChA-1 cholangiocarcinoma cells and polarized normal rat cholangiocyte monolayers. ATP release increased rapidly during cell swelling induced by hypotonic exposure. In Mz-ChA-1 cells, removal of extracellular ATP (apyrase) and P2 receptor blockade (suramin) reversibly inhibited whole cell Cl− current activation and prevented cell volume recovery during hypotonic stress. Moreover, exposure to apyrase induced cell swelling under isotonic conditions. In intact normal rat cholangiocyte monolayers, hypotonic perfusion activated apical Cl−currents, which were inhibited by addition of apyrase and suramin to bathing media. These findings indicate that modulation of ATP release by the cellular hydration state represents a potential signal coordinating cell volume with membrane Cl− permeability and transepithelial Cl−secretion.

Vesicular exocytosis contributes to volume-sensitive ATP release in biliary cells

2004 ◽  
Vol 286 (4) ◽  
pp. G538-G546 ◽  
Author(s):  
David Gatof ◽  
Gordan Kilic ◽  
J. Gregory Fitz
Keyword(s):  
Cell Volume ◽  
Purinergic Signaling ◽  
Atp Release ◽  
Fold Increase ◽  
Extracellular Atp ◽  
Pi3 Kinase ◽  
Cholangiocarcinoma Cell ◽  
Vesicular Exocytosis ◽  
Phosphoinositide 3 Kinase ◽  
Regulatory Properties

Extracellular ATP is a potent autocrine/paracrine signal that regulates a broad range of liver functions through activation of purinergic receptors. In biliary epithelium, increases in cell volume stimulate ATP release through a phosphoinositide 3-kinase (PI3-kinase)-dependent mechanism. Because PI3-kinase also regulates vesicular exocytosis, the purpose of these studies was to determine whether volume-stimulated vesicular exocytosis contributes to cellular ATP release. In a human cholangiocarcinoma cell line, exocytosis was measured by using the plasma membrane marker FM1–43, whereas ATP release was assessed by using a luciferase-luciferin assay. Under basal conditions, cholangiocytes exhibited constitutive exocytosis at a rate of 1.6%/min, and low levels of extracellular ATP were detected at 48.2 arbitrary light units. Increases in cholangiocyte cell volume induced by hypotonic exposure resulted in a 10-fold increase in the rate of exocytosis and a robust 35-fold increase in ATP release. Both vesicular exocytosis and ATP release were proportional to cell volume, and both exhibited similar regulatory properties including: 1) dependence on intact PI3-kinase, 2) attenuation by inhibition of PKC, and 3) potentiation by activation of PKC before hypotonic exposure. These findings demonstrate that increases in cholangiocyte cell volume stimulate ATP release and vesicular exocytosis through similar regulatory paradigms. Functional interactions among cell volume, PKC, and PI3-kinase modulate exocytosis, thereby regulating ATP release and purinergic signaling in cholangiocytes. It is hypothesized that PKC is involved in the recruitment of a volume-sensitive vesicular pool to a readily releasable state.

scholarly journals Chronic fructose renders pancreatic β-cells hyper-responsive to glucose-stimulated insulin secretion through extracellular ATP signaling

2019 ◽  
Vol 317 (1) ◽  
pp. E25-E41 ◽  
Author(s):  
Clarissa Bartley ◽  
Thierry Brun ◽  
Lucie Oberhauser ◽  
Mariagrazia Grimaldi ◽  
Filippo Molica ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Atp Release ◽  
Extracellular Atp ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Cellular Mechanisms ◽  
Kinase Activation ◽  
Glucose Stimulated Insulin Secretion ◽  
Insulinoma Cells ◽  
Atp Signaling

Fructose is widely used as a sweetener in processed food and is also associated with metabolic disorders, such as obesity. However, the underlying cellular mechanisms remain unclear, in particular, regarding the pancreatic β-cell. Here, we investigated the effects of chronic exposure to fructose on the function of insulinoma cells and isolated mouse and human pancreatic islets. Although fructose per se did not acutely stimulate insulin exocytosis, our data show that chronic fructose rendered rodent and human β-cells hyper-responsive to intermediate physiological glucose concentrations. Fructose exposure reduced intracellular ATP levels without affecting mitochondrial function, induced AMP-activated protein kinase activation, and favored ATP release from the β-cells upon acute glucose stimulation. The resulting increase in extracellular ATP, mediated by pannexin1 (Panx1) channels, activated the calcium-mobilizer P2Y purinergic receptors. Immunodetection revealed the presence of both Panx1 channels and P2Y1 receptors in β-cells. Addition of an ectonucleotidase inhibitor or P2Y1 agonists to naïve β-cells potentiated insulin secretion stimulated by intermediate glucose, mimicking the fructose treatment. Conversely, the P2Y1 antagonist and Panx1 inhibitor reversed the effects of fructose, as confirmed using Panx1-null islets and by the clearance of extracellular ATP by apyrase. These results reveal an important function of ATP signaling in pancreatic β-cells mediating fructose-induced hyper-responsiveness.

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