scholarly journals Cutaneous Sensory Neurons Expressing the Mrgprd Receptor Sense Extracellular ATP and Are Putative Nociceptors

2008 ◽  
Vol 99 (4) ◽  
pp. 1581-1589 ◽  
Author(s):  
G. Dussor ◽  
M. J. Zylka ◽  
D. J. Anderson ◽  
E. W. McCleskey
Keyword(s):  
Sensory Neurons ◽  
Sensory Modality ◽  
Atp Release ◽  
Extracellular Atp ◽  
Stratum Granulosum ◽  
P2x3 Receptors ◽  
Long Duration ◽  
Mouse Dorsal Root Ganglion ◽  
Mu Opioids ◽  
External Stimuli

Sensory neurons expressing the Mrgprd receptor are known to innervate the outermost living layer of the epidermis, the stratum granulosum. The sensory modality that these neurons signal and the stimulus that they respond to are not established, although immunocytochemical data suggest they could be nonpeptidergic nociceptors. Using patch clamp of dissociated mouse dorsal root ganglion (DRG) neurons, the present study demonstrates that Mrgprd+ neurons have several properties typical of nociceptors: long-duration action potentials, TTX-resistant Na+ current, and Ca2+ currents that are inhibited by mu opioids. Remarkably, Mrgprd+ neurons respond almost exclusively to extracellular ATP with currents similar to homomeric P2X3 receptors. They show little or no sensitivity to other putative nociceptive agonists, including capsaicin, cinnamaldehyde, menthol, pH 6.0, or glutamate. These properties, together with selective innervation of the stratum granulosum, indicate that Mrgprd+ neurons are nociceptors in the outer epidermis and may respond indirectly to external stimuli by detecting ATP release in the skin.

scholarly journals The signaling role of extracellular ATP in co-culture of Shiraia sp. S9 and Pseudomonas fulva SB1 for enhancing hypocrellin A production

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Xin Ping Li ◽  
Lu Lu Zhou ◽  
Yan Hua Guo ◽  
Jian Wen Wang
Keyword(s):  
Atp Release ◽  
Specific Inhibitor ◽  
Extracellular Atp ◽  
Oxidase Inhibitor ◽  
Disulfonic Acid ◽  
Early Event ◽  
Fungal Metabolites ◽  
Extracellular Signaling ◽  
Hypocrellin A

Abstract Background Adenosine 5′-triphosphate (ATP) plays both a central role as an intracellular energy source, and a crucial extracellular signaling role in diverse physiological processes of animals and plants. However, there are less reports concerning the signaling role of microbial extracellular ATP (eATP). Hypocrellins are effective anticancer photodynamic therapy (PDT) agents from bambusicolous Shiraia fungi. The co-culture of Shiraia sp. S9 and a bacterium Pseudomonas fulva SB1 isolated from Shiraia fruiting bodies was established for enhanced hypocrellin A (HA) production. The signaling roles of eATP to mediate hypocrellin biosynthesis were investigated in the co-culture. Results The co-culture induced release of eATP at 378 nM to the medium around 4 h. The eATP release was interdependent on cytosolic Ca2+ concentration and reactive oxygen species (ROS) production, respectively. The eATP production could be suppressed by the Ca2+ chelator EGTA or abolished by the channel blocker La3+, ROS scavenger vitamin C and NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI). The bacterium-induced H2O2 production was strongly inhibited by reactive blue (RB), a specific inhibitor of membrane purinoceptors, but dependent on the induced Ca2+ influx in the co-culture. On the other hand, the application of exogenous ATP (exATP) at 10–300 µM to Shiraia cultures also promoted fungal conidiation and HA production, both of which were blocked effectively by the purinoceptor inhibitors pyridoxalphosphate-6-azophenyl-2′, 4′-disulfonic acid (PPADS) and RB, and ATP hydrolase apyrase. Both the induced expression of HA biosynthetic genes and HA accumulation were inhibited significantly under the blocking of the eATP or Ca2+ signaling, and the scavenge of ROS in the co-culture. Conclusions Our results indicate that eATP release is an early event during the intimate bacterial–fungal interaction and eATP plays a signaling role in the bacterial elicitation on fungal metabolites. Ca2+ and ROS are closely linked for activation of the induced ATP release and its signal transduction. This is the first report on eATP production in the fungal–bacterial co-culture and its involvement in the induced biosynthesis of fungal metabolites. Graphic abstract

Rehabilitation of Post Stroke Sensory Dysfunction—A Scoping Review

2021 ◽  
pp. 251660852098429
Author(s):  
Dorcas B. C. Gandhi ◽  
Ivy Anne Sebastian ◽  
Komal Bhanot
Keyword(s):  
Motor Behavior ◽  
Sensory Modality ◽  
Sensory System ◽  
Sensory Stimulation ◽  
Current Evidence ◽  
Cochrane Library ◽  
Post Stroke ◽  
Sensory Dysfunction ◽  
Electronic Database Search ◽  
External Stimuli

Sensory dysfunction is one of the common impairments that occurs post stroke. With sensory changes in all modalities, it also affects the quality of life and incites suicidal thoughts. The article attempts to review and describe the current evidence of various approaches of assessment and rehabilitation for post-stroke sensory dysfunction. After extensive electronic database search across Medline, Embase, EBSCO, and Cochrane library, it generated 2433 results. After screening according to inclusion and exclusion criteria, we included 11 studies. We categorized data based on type of sensory deficits and prevalence, role of sensory system on motor behavior, type of intervention, sensory modality targeted, and dosage of intervention and outcome measures used for rehabilitation. Results found the strong evidence of involvement of primary and secondary motor areas involved in processing and responding to somatosensation, respectively. We divided rehabilitation approaches into sensory stimulation approach and sensory retraining approach focused on using external stimuli and relearning, respectively. However, with varied aims and targeted sensory involvement, the study applicability is affected. Thus, this emerges the need of extensive research in future for evidence-based practice of assessments and rehabilitation on post-stroke sensory rehabilitation.

The role of interneurons in controlling the tail-withdrawal reflex in Aplysia: a network model

1993 ◽  
Vol 70 (5) ◽  
pp. 1777-1786 ◽  
Author(s):  
J. A. White ◽  
I. Ziv ◽  
L. J. Cleary ◽  
D. A. Baxter ◽  
J. H. Byrne
Keyword(s):  
Synaptic Plasticity ◽  
Sensory Neurons ◽  
Network Model ◽  
Motor Neurons ◽  
Excitatory Postsynaptic Potential ◽  
Layer Model ◽  
Neural Network Models ◽  
Plastic Properties ◽  
Withdrawal Reflex ◽  
Long Duration

1. The contributions of monosynaptic and polysynaptic circuitry to the tail-withdrawal reflex in the marine mollusk Aplysia californica were assessed by the use of physiologically based neural network models. Effects of monosynaptic circuitry were examined by the use of a two-layer network model with four sensory neurons in the input layer and one motor neuron in the output layer. Results of these simulations indicated that the monosynaptic circuit could not account fully for long-duration responses of tail motor neurons elicited by tail stimulation. 2. A three-layer network model was constructed by interposing a layer of two excitatory interneurons between the input and output layers of the two-layer network model. These interneurons had properties mimicking those of the recently described interneuron LP117, receiving excitatory input from pleural sensory neurons and evoking a biphasic excitatory postsynaptic potential (EPSP) in pedal motor neurons (Cleary and Byrne 1993). The three-layer model could account for long-duration responses in motor neurons. 3. Sensory neurons are a known site of plasticity in Aplysia. Synaptic plasticity was incorporated into the three-layer model by altering the magnitudes of conductance changes evoked in motor neurons and interneurons by presynaptic sensory neurons. In these simulations the excitatory interneurons converted an amplitude-coded input into an amplitude- and duration-coded output, allowing the three-layer network to support a large range of output amplitudes and durations. 4. Synaptic plasticity at more than one locus modified dramatically the input-output relationship of the three-layer network model. This feature gave the model redundancy in its plastic properties and points to the possibility of distributed memory in the circuitry mediating withdrawal reflexes in Aplysia. Multiple sites of control over the response of the network would likely allow a more diverse repertoire of responses.

scholarly journals Dynamic regulation of extracellular ATP in Escherichia coli

2017 ◽  
Vol 474 (8) ◽  
pp. 1395-1416 ◽  
Author(s):  
Cora Lilia Alvarez ◽  
Gerardo Corradi ◽  
Natalia Lauri ◽  
Irene Marginedas-Freixa ◽  
María Florencia Leal Denis ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Atpase Activity ◽  
Atp Release ◽  
Membrane Vesicles ◽  
Fold Increase ◽  
Extracellular Atp ◽  
Outer Membrane Vesicles ◽  
Dynamic Regulation ◽  
E Coli

We studied the kinetics of extracellular ATP (ATPe) in Escherichia coli and their outer membrane vesicles (OMVs) stimulated with amphipatic peptides melittin (MEL) and mastoparan 7 (MST7). Real-time luminometry was used to measure ATPe kinetics, ATP release, and ATPase activity. The latter was also determined by following [32P]Pi released from [γ-32P]ATP. E. coli was studied alone, co-incubated with Caco-2 cells, or in rat jejunum segments. In E. coli, the addition of [γ-32P]ATP led to the uptake and subsequent hydrolysis of ATPe. Exposure to peptides caused an acute 3-fold (MST7) and 7-fold (MEL) increase in [ATPe]. In OMVs, ATPase activity increased linearly with [ATPe] (0.1–1 µM). Exposure to MST7 and MEL enhanced ATP release by 3–7 fold, with similar kinetics to that of bacteria. In Caco-2 cells, the addition of ATP to the apical domain led to a steep [ATPe] increase to a maximum, with subsequent ATPase activity. The addition of bacterial suspensions led to a 6–7 fold increase in [ATPe], followed by an acute decrease. In perfused jejunum segments, exposure to E. coli increased luminal ATP 2 fold. ATPe regulation of E. coli depends on the balance between ATPase activity and ATP release. This balance can be altered by OMVs, which display their own capacity to regulate ATPe. E. coli can activate ATP release from Caco-2 cells and intestinal segments, a response which in vivo might lead to intestinal release of ATP from the gut lumen.

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.

P2X7 receptor cross-talk regulates ATP-induced pannexin 1 internalization

2017 ◽  
Vol 474 (13) ◽  
pp. 2133-2144 ◽  
Author(s):  
Andrew K.J. Boyce ◽  
Leigh Anne Swayne
Keyword(s):  
Nervous System ◽  
Cross Talk ◽  
Purinergic Receptors ◽  
Atp Release ◽  
Extracellular Atp ◽  
Signalling Pathways ◽  
Physical Interaction ◽  
Cell Periphery ◽  
Dependent Manner ◽  
Pannexin 1

In the nervous system, extracellular ATP levels transiently increase in physiological and pathophysiological circumstances, effecting key signalling pathways in plasticity and inflammation through purinergic receptors. Pannexin 1 (Panx1) forms ion- and metabolite-permeable channels that mediate ATP release and are particularly enriched in the nervous system. Our recent study demonstrated that elevation of extracellular ATP triggers Panx1 internalization in a concentration- and time-dependent manner. Notably, this effect was sensitive to inhibition of ionotropic P2X7 purinergic receptors (P2X7Rs). Here, we report our novel findings from the detailed investigation of the mechanism underlying P2X7R–Panx1 cross-talk in ATP-stimulated internalization. We demonstrate that extracellular ATP triggers and is required for the clustering of P2X7Rs and Panx1 on Neuro2a cells through an extracellular physical interaction with the Panx1 first extracellular loop (EL1). Importantly, disruption of P2X7R–Panx1 clustering by mutation of tryptophan 74 within the Panx1 EL1 inhibits Panx1 internalization. Notably, P2X7R–Panx1 clustering and internalization are independent of P2X7R-associated intracellular signalling pathways (Ca2+ influx and Src activation). Further analysis revealed that cholesterol is required for ATP-stimulated P2X7R–Panx1 clustering at the cell periphery. Taken together, our data suggest that extracellular ATP induces and is required for Panx1 EL1-mediated, cholesterol-dependent P2X7R–Panx1 clustering and endocytosis. These findings have important implications for understanding the role of Panx1 in the nervous system and provide important new insights into Panx1–P2X7R cross-talk.

scholarly journals Toll-Like Receptor-Triggered Calcium Mobilization Protects Mice against Bacterial Infection through Extracellular ATP Release

2014 ◽  
Vol 82 (12) ◽  
pp. 5076-5085 ◽  
Author(s):  
Hua Ren ◽  
Yunfei Teng ◽  
Binghe Tan ◽  
Xiaoyu Zhang ◽  
Wei Jiang ◽  
...  
Keyword(s):  
Immune Responses ◽  
Pyridoxal Phosphate ◽  
Atp Release ◽  
Extracellular Atp ◽  
Calcium Mobilization ◽  
Innate Immune ◽  
Disulfonic Acid ◽  
Dependent Manner ◽  
Innate Immune Responses ◽  
Toll Like Receptor

ABSTRACTExtracellular ATP (eATP), released as a “danger signal” by injured or stressed cells, plays an important role in the regulation of immune responses, but the relationship between ATP release and innate immune responses is still uncertain. In this study, we demonstrated that ATP was released through Toll-like receptor (TLR)-associated signaling in bothEscherichia coli-infected mice and lipopolysaccharide (LPS)- or Pam3CSK4-treated macrophages. This ATP release could be blocked completely only byN-ethylmaleimide (NEM), not by carbenoxolone (CBX), flufenamic acid (FFA), or probenecid, suggesting the key role of exocytosis in this process. Furthermore, LPS-induced ATP release could also be reduced dramatically through suppressing calcium mobilization by use of U73122, caffeine, and thapsigargin (TG). In addition, the secretion of interleukin-1β (IL-1β) and CCL-2 was enhanced significantly by ATP, in a time- and dose-dependent manner. Meanwhile, macrophage-mediated phagocytosis of bacteria was also promoted significantly by ATP stimulation. Furthermore, extracellular ATP reduced the number of invading bacteria and protected mice from peritonitis by activating purinergic receptors. Mechanistically, phosphorylation of AKT and ERK was overtly increased by ATP in antibacterial immune responses. Accordingly, if we blocked the P2X- and P2Y-associated signaling pathway by using suramin and pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid), tetrasodium salt (PPADS), the ATP-enhanced immune response was restrained significantly. Taken together, our findings reveal an internal relationship between danger signals and TLR signaling in innate immune responses, which suggests a potential therapeutic significance of calcium mobilization-mediated ATP release in infectious diseases.

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 Attenuated, flow-induced ATP release contributes to absence of flow-sensitive, purinergic Cai2+ signaling in human ADPKD cyst epithelial cells

2009 ◽  
Vol 296 (6) ◽  
pp. F1464-F1476 ◽  
Author(s):  
Chang Xu ◽  
Boris E. Shmukler ◽  
Katherine Nishimura ◽  
Elzbieta Kaczmarek ◽  
Sandro Rossetti ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Atp Hydrolysis ◽  
Atp Release ◽  
Extracellular Atp ◽  
Mrna Levels ◽  
Normal Cells ◽  
Altered Expression ◽  
Cyst Cells ◽  
Autosomal Dominant Polycystic Kidney ◽  
Renal Tubular

Flow-induced cytosolic Ca2+ Cai2+ signaling in renal tubular epithelial cells is mediated in part through P2 receptor (P2R) activation by locally released ATP. The ability of P2R to regulate salt and water reabsorption has suggested a possible contribution of ATP release and paracrine P2R activation to cystogenesis and/or enlargement in autosomal dominant polycystic kidney disease (ADPKD). We and others have demonstrated in human ADPKD cyst cells the absence of flow-induced Cai2+ signaling exhibited by normal renal epithelial cells. We now extend these findings to primary and telomerase-immortalized normal and ADPKD epithelial cells of different genotype and of both proximal and distal origins. Flow-induced elevation of Cai2+ concentration ([Ca2+]i) was absent from ADPKD cyst cells, but in normal cells was mediated by flow-sensitive ATP release and paracrine P2R activation, modulated by ecto-nucleotidase activity, and abrogated by P2R inhibition or extracellular ATP hydrolysis. In contrast to the elevated ATP release from ADPKD cells in static isotonic conditions or in hypotonic conditions, flow-induced ATP release from cyst cells was lower than from normal cells. Extracellular ATP rapidly reduced thapsigargin-elevated [Ca2+]i in both ADPKD cyst and normal cells, but cyst cells lacked the subsequent, slow, oxidized ATP-sensitive [Ca2+]i recovery present in normal cells. Telomerase-immortalized cyst cells also exhibited altered CD39 and P2X7 mRNA levels. Thus the loss of flow-induced, P2R-mediated Cai2+ signaling in human ADPKD cyst epithelial cells was accompanied by reduced flow-sensitive ATP release, altered purinergic regulation of store-operated Ca2+ entry, and altered expression of gene products controlling extracellular nucleotide signaling.

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