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.

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.

scholarly journals Structure versus function: Are new conformations of pannexin 1 yet to be resolved?

2021 ◽  
Vol 153 (5) ◽  
Author(s):  
Carsten Mim ◽  
Guy Perkins ◽  
Gerhard Dahl
Keyword(s):  
Structural Information ◽  
Purinergic Signaling ◽  
Atp Release ◽  
Strong Support ◽  
Decisive Role ◽  
Chloride Ions ◽  
Pannexin 1 ◽  
Selective Membrane ◽  
Selective Channel ◽  
Structure Versus

Pannexin 1 (Panx1) plays a decisive role in multiple physiological and pathological settings, including oxygen delivery to tissues, mucociliary clearance in airways, sepsis, neuropathic pain, and epilepsy. It is widely accepted that Panx1 exerts its role in the context of purinergic signaling by providing a transmembrane pathway for ATP. However, under certain conditions, Panx1 can also act as a highly selective membrane channel for chloride ions without ATP permeability. A recent flurry of publications has provided structural information about the Panx1 channel. However, while these structures are consistent with a chloride selective channel, none show a conformation with strong support for the ATP release function of Panx1. In this Viewpoint, we critically assess the existing evidence for the function and structure of the Panx1 channel and conclude that the structure corresponding to the ATP permeation pathway is yet to be determined. We also list a set of additional topics needing attention and propose ways to attain the large-pore, ATP-permeable conformation of the Panx1 channel.

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.

scholarly journals Distinct purinergic signaling pathways in prepubescent mouse spermatogonia

2016 ◽  
Vol 148 (3) ◽  
pp. 253-271 ◽  
Author(s):  
David Fleck ◽  
Nadine Mundt ◽  
Felicitas Bruentgens ◽  
Petra Geilenkirchen ◽  
Patricia A. Machado ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Purinergic Signaling ◽  
Cell Communication ◽  
Atp Release ◽  
Cell Types ◽  
Control Male ◽  
Electrophysiological Recordings ◽  
Unique Approach

Spermatogenesis ranks among the most complex, yet least understood, developmental processes. The physiological principles that control male germ cell development in mammals are notoriously difficult to unravel, given the intricate anatomy and complex endo- and paracrinology of the testis. Accordingly, we lack a conceptual understanding of the basic signaling mechanisms within the testis, which control the seminiferous epithelial cycle and thus govern spermatogenesis. Here, we address paracrine signal transduction in undifferentiated male germ cells from an electrophysiological perspective. We identify distinct purinergic signaling pathways in prepubescent mouse spermatogonia, both in vitro and in situ. ATP—a dynamic, widespread, and evolutionary conserved mediator of cell to cell communication in various developmental contexts—activates at least two different spermatogonial purinoceptor isoforms. Both receptors operate within nonoverlapping stimulus concentration ranges, display distinct response kinetics and, in the juvenile seminiferous cord, are uniquely expressed in spermatogonia. We further find that spermatogonia express Ca2+-activated large-conductance K+ channels that appear to function as a safeguard against prolonged ATP-dependent depolarization. Quantitative purine measurements additionally suggest testicular ATP-induced ATP release, a mechanism that could increase the paracrine radius of initially localized signaling events. Moreover, we establish a novel seminiferous tubule slice preparation that allows targeted electrophysiological recordings from identified testicular cell types in an intact epithelial environment. This unique approach not only confirms our in vitro findings, but also supports the notion of purinergic signaling during the early stages of spermatogenesis.

scholarly journals Endotoxin-induced autocrine ATP signaling inhibits neutrophil chemotaxis through enhancing myosin light chain phosphorylation

2017 ◽  
Vol 114 (17) ◽  
pp. 4483-4488 ◽  
Author(s):  
Xu Wang ◽  
Weiting Qin ◽  
Xiaohan Xu ◽  
Yuyun Xiong ◽  
Yisen Zhang ◽  
...  
Keyword(s):  
Light Chain ◽  
Connexin 43 ◽  
Myosin Light Chain ◽  
Calcium Influx ◽  
Neutrophil Migration ◽  
Atp Release ◽  
Human Neutrophils ◽  
Neutrophil Chemotaxis ◽  
P2x1 Receptor ◽  
Atp Signaling

Although the neutrophil recruitment cascade during inflammation has been well described, the molecular players that halt neutrophil chemotaxis remain unclear. In this study, we found that lipopolysaccharide (LPS) was a potent stop signal for chemotactic neutrophil migration. Treatment with an antagonist of the ATP receptor (P2X1) in primary human neutrophils or knockout of the P2X1 receptor in neutrophil-like differentiated HL-60 (dHL-60) cells recovered neutrophil chemotaxis. Further observations showed that LPS-induced ATP release through connexin 43 (Cx43) hemichannels was responsible for the activation of the P2X1 receptor and the subsequent calcium influx. Increased intracellular calcium stopped neutrophil chemotaxis by activating myosin light chain (MLC) through the myosin light chain kinase (MLCK)-dependent pathway. Taken together, these data identify a previously unknown function of LPS-induced autocrine ATP signaling in inhibiting neutrophil chemotaxis by enhancing MLC phosphorylation, which provides important evidence that stoppage of neutrophil chemotaxis at infectious foci plays a key role in the defense against invading pathogens.

scholarly journals Mechanical stretch activates piezo1 in caveolae of alveolar type I cells to trigger ATP release and paracrine stimulation of surfactant secretion from alveolar type II cells

2020 ◽  
Vol 34 (9) ◽  
pp. 12785-12804 ◽  
Author(s):  
Kathrin Diem ◽  
Michael Fauler ◽  
Giorgio Fois ◽  
Andreas Hellmann ◽  
Natalie Winokurow ◽  
...  
Keyword(s):  
Atp Release ◽  
Mechanical Stretch ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells ◽  
Surfactant Secretion ◽  
I Cells ◽  
Stimulation Of

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 HIV gp120 Protein Increases the Function of Connexin 43 Hemichannels and Pannexin-1 Channels in Astrocytes: Repercussions on Astroglial Function

2020 ◽  
Vol 21 (7) ◽  
pp. 2503 ◽  
Author(s):  
Rosario Gajardo-Gómez ◽  
Cristian A. Santibañez ◽  
Valeria C. Labra ◽  
Gonzalo I. Gómez ◽  
Eliseo A. Eugenin ◽  
...  
Keyword(s):  
Connexin 43 ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Purinergic Signaling ◽  
Atp Release ◽  
P38 Map Kinase ◽  
Motor Deficits ◽  
Pannexin 1 ◽  
Channel Opening ◽  
Wide Range

At least half of human immunodeficiency virus (HIV)-infected individuals suffer from a wide range of cognitive, behavioral and motor deficits, collectively known as HIV-associated neurocognitive disorders (HAND). The molecular mechanisms that amplify damage within the brain of HIV-infected individuals are unknown. Recently, we described that HIV augments the opening of connexin-43 (Cx43) hemichannels in cultured human astrocytes, which result in the collapse of neuronal processes. Whether HIV soluble viral proteins such as gp120, can regulate hemichannel opening in astrocytes is still ignored. These channels communicate the cytosol with the extracellular space during pathological conditions. We found that gp120 enhances the function of both Cx43 hemichannels and pannexin-1 channels in mouse cortical astrocytes. These effects depended on the activation of IL-1β/TNF-α, p38 MAP kinase, iNOS, cytoplasmic Ca2+ and purinergic signaling. The gp120-induced channel opening resulted in alterations in Ca2+ dynamics, nitric oxide production and ATP release. Although the channel opening evoked by gp120 in astrocytes was reproduced in ex vivo brain preparations, these responses were heterogeneous depending on the CA1 region analyzed. We speculate that soluble gp120-induced activation of astroglial Cx43 hemichannels and pannexin-1 channels could be crucial for the pathogenesis of HAND.

scholarly journals Extracellular ATP signaling in the rabbit lung: erythrocytes as determinants of vascular resistance

2003 ◽  
Vol 285 (2) ◽  
pp. H693-H700 ◽  
Author(s):  
Randy S. Sprague ◽  
Jeffrey J. Olearczyk ◽  
Dana M. Spence ◽  
Alan H. Stephenson ◽  
Robert W. Sprung ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Methyl Ester ◽  
Vascular Resistance ◽  
Flow Rate ◽  
Vascular Endothelium ◽  
Pulmonary Circulation ◽  
Blood Cells ◽  
Atp Release ◽  
Rabbit Lung ◽  
Atp Signaling

Previously, it was reported that red blood cells (RBCs) are required to demonstrate participation of nitric oxide (NO) in the regulation of rabbit pulmonary vascular resistance (PVR). RBCs do not synthesize NO; hence, we postulated that ATP, present in millimolar amounts in RBCs, was the mediator, which evoked NO synthesis in the vascular endothelium. First, we found that deformation of RBCs, as occurs on passage across the pulmonary circulation with increasing flow rate, evoked increments in ATP release. Here, ATP (300 nM), administered to isolated, salt solution-perfused (PSS) rabbit lungs, decreased total and upstream (arterial) PVR, a response inhibited by NG-nitro-l-arginine methyl ester (l-NAME, 100 μM). In lungs perfused with PSS containing RBCs, l-NAME increased total and upstream PVR. In lungs perfused with PSS containing glibenclamide-treated RBCs, which inhibits ATP release, l-NAME was without effect. Apyrase grade VII (8 U/ml), which degrades ATP to AMP, was without effect on PVR in PSS-perfused lungs. These results are consistent with the hypothesis that ATP, released from RBCs as they traverse the pulmonary circulation, evokes endogenous NO synthesis.

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