• CA1
• CA3
• Dentate gyrus
• GluA2
• GluN1
• Nest-building behavior
• P2X4

• Animals
• Ketamine/administration & dosage
• Ketamine/pharmacology
• Mice
• Hippocampus/drug effects
• Hippocampus/metabolism
• Male
• Behavior, Animal/drug effects
• Receptors, Purinergic P2X1/metabolism
• Receptors, Purinergic P2X1/drug effects
• Receptors, Purinergic P2X7/metabolism
• Receptors, Purinergic P2X7/drug effects
• Excitatory Amino Acid Antagonists/administration & dosage
• Excitatory Amino Acid Antagonists/pharmacology
• Age Factors
• Social Interaction/drug effects
• Memory, Short-Term/drug effects
• Motor Activity/drug effects
• Receptors, N-Methyl-D-Aspartate/metabolism

• CSD
• Migraine
• Neuroinflammation
• P2X7R
• Subcortical spread

• Cortical Spreading Depression/drug effects
• Cortical Spreading Depression/physiology
• Animals
• Purinergic P2X Receptor Antagonists/pharmacology
• Neuroinflammatory Diseases
• Male
• Receptors, Purinergic P2X7/metabolism
• Receptors, Purinergic P2X7/drug effects
• Optogenetics
• Mice
• Migraine Disorders/physiopathology
• Migraine Disorders/metabolism
• Migraine Disorders/drug therapy
• Neurons/drug effects
• Mice, Inbred C57BL
• Niacinamide/analogs & derivatives
• Piperazines

• TSA-2017-14206 Hacettepe University Research Projects Management System

• ATP
• DRG neurons
• P2 receptor
• TRPV1 channel
• calcium ions
• capsaicin
• desensitization
• resensitization

• Brachial plexus avulsion
• PKC/ MAPK/NOX pathway
• neuro-inflammatory infiltration
• neuropathic pain
• oxidative damage
• quercetin

• Rats
• Animals
• Hyperalgesia/drug therapy
• Hyperalgesia/metabolism
• Quercetin/pharmacology
• Quercetin/therapeutic use
• Hydrogen Peroxide
• Brachial Plexus/metabolism
• Brachial Plexus/surgery
• Neuralgia/drug therapy
• Spinal Cord Dorsal Horn/metabolism
• Oxidative Stress

• Chemical coding
• Enteric nervous system
• Gastroenterology
• Inflammatory bowel diseases
• P2X7 receptor
• Purinergic signaling

• Animals
• Colitis, Ulcerative/drug therapy
• Enteric Nervous System
• Humans
• Inflammatory Bowel Diseases/drug therapy
• Receptors, Purinergic P2X7
• Submucous Plexus

• 6-hydroxydopamine
• P2X4R
• Parkinson's disease
• TrkB
• apomorphine
• autophagy
• brain-derived neurotrophic factor
• dopaminergic neurons
• neuron degeneration

Gating of the ATP-activated channel P2X2 has been shown to be dependent not only on [ATP] but also on membrane voltage, despite the absence of a canonical voltage-sensor domain. We aimed to investigate the structural rearrangements of rat P2X2 during ATP- and voltage-dependent gating, using a voltage-clamp fluorometry technique. We observed fast and linearly voltage-dependent fluorescence intensity (F) changes at Ala337 and Ile341 in the TM2 domain, which could be due to the electrochromic effect, reflecting the presence of a converged electric field. We also observed slow and voltage-dependent F changes at Ala337, which reflect structural rearrangements. Furthermore, we determined that the interaction between Ala337 in TM2 and Phe44 in TM1, which are in close proximity in the ATP-bound open state, is critical for activation. Taking these results together, we propose that the voltage dependence of the interaction within the converged electric field underlies the voltage-dependent gating.

• P2X2
• fluorescent unnatural amino acid
• molecular biophysics
• structural biology
• voltage-clamp fluorometry
• xenopus

• Adenosine receptors
• Depression
• Locomotor activity
• P2X receptor
• P2Y receptor
• Purinergic transmission

• ATP
• P2X7 receptor
• development
• neonatal seizures
• purinergic signalling

• Animals
• Central Nervous System/growth & development
• Central Nervous System/metabolism
• Disease Models, Animal
• Humans
• Hypothermia, Induced/methods
• Infant
• Infant, Newborn
• Molecular Targeted Therapy
• Purinergic P2 Receptor Antagonists/pharmacology
• Purines/metabolism
• Receptors, Purinergic P1/metabolism
• Receptors, Purinergic P2/metabolism
• Seizures/drug therapy
• Seizures/etiology
• Seizures/therapy

• 17/CDA/4708, 16/RC/3948 Science Foundation Ireland

• analgesics
• anesthetics
• pain
• pharmacogenetics

• ATP-gated channels
• Double-electrode patch clamp
• Electrophysiology
• Oocytes
• P2X
• Receptor function
• Surface trafficking
• Xenopus

• ATP
• Ca2+ signaling
• dental pulp stem cells
• osteogenesis

• Cell Membrane/chemistry
• Cell Membrane/metabolism
• Computer Simulation
• Humans
• Ion Channels/chemistry
• Ion Channels/metabolism
• Membrane Lipids/chemistry
• Membrane Lipids/metabolism
• Membrane Proteins/chemistry
• Membrane Proteins/metabolism
• Models, Biological
• Models, Molecular
• Molecular Docking Simulation
• Protein Conformation
• Receptors, G-Protein-Coupled/chemistry
• Receptors, G-Protein-Coupled/metabolism

• R01 HL128537 NHLBI NIH HHS
• 156236 CIHR

• Gene polymorphisms
• Ligand-gated ion channel 7
• Meta-analysis
• Purinergic receptor P2X
• Tuberculosis

Adenosine 5′-triphosphate acts as an extracellular signalling molecule (purinergic signalling), as well as an intracellular energy source. Adenosine 5′-triphosphate receptors have been cloned and characterised. P1 receptors are selective for adenosine, a breakdown product of adenosine 5′-triphosphate after degradation by ectonucleotidases. Four subtypes are recognised, A₁, A_2A, A_2B and A₃ receptors. P2 receptors are activated by purine and by pyrimidine nucleotides. P2X receptors are ligand-gated ion channel receptors (seven subunits (P2X1-7)), which form trimers as both homomultimers and heteromultimers. P2Y receptors are G protein-coupled receptors (eight subtypes (P2Y_{1/2/4/6/11/12/13/14})). There is both purinergic short-term signalling and long-term (trophic) signalling. The cloning of P2X-like receptors in primitive invertebrates suggests that adenosine 5′-triphosphate is an early evolutionary extracellular signalling molecule. Selective purinoceptor agonists and antagonists with therapeutic potential have been developed for a wide range of diseases, including thrombosis and stroke, dry eye, atherosclerosis, kidney failure, osteoporosis, bladder incontinence, colitis, neurodegenerative diseases and cancer.

• Adenosine 5′-triphosphate
• P1 receptor
• P2X receptor
• P2Y receptor
• adenosine

• ATP
• P2X receptor
• Patch clamp
• membrane trafficking
• purinergic receptor
• receptor re-sensitization

Extracellular nucleotides, such as adenosine triphosphate (ATP), are released from host cells including nerve termini, immune cells, injured or dead cells, and the commensal bacteria that reside in the gut lumen. Extracellular ATP interacts with the host through purinergic receptors, and promotes intercellular and bacteria-host communication to maintain the tissue homeostasis. However, the release of massive concentrations of ATP into extracellular compartments initiates acute and chronic inflammatory responses through the activation of immunocompetent cells (e.g., T cells, macrophages, and mast cells). In this review, we focus on the functions of ATP as a pathophysiologic mediator that is required for the induction and resolution of inflammation and inter-species communication.

• ATP
• adenosine
• commensal bacteria
• inflammatory bowel disease (IBD)
• inter-species communication
• purinergic pathway

• ATP
• Panx1
• inflammation
• pannexin
• purinergic signaling
• regeneration

• Animals
• Female
• Male
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Muscle Contraction/physiology
• Muscle, Smooth/metabolism
• Myocytes, Smooth Muscle/metabolism
• Receptors, Purinergic P2X4/metabolism
• Urinary Bladder/metabolism

• K99 DK095922 NIDDK NIH HHS
• R00 DK095922 NIDDK NIH HHS
• R01 DK083299 NIDDK NIH HHS

• Diadenosine tetraphosphate
• Dinucleotides
• Diquafosol
• Purinergic receptors

• Animals
• Aqueous Humor/metabolism
• Cornea/metabolism
• Dinucleoside Phosphates/physiology
• Humans
• Second Messenger Systems
• Tears/chemistry
• Tissue Distribution/physiology

Extracellular ATP acts on the P2X family of ligand-gated ion channels and several members of the P2Y family of G protein-coupled receptors to mediate intercellular communication among many cell types including bone-forming osteoblasts. It is known that multiple P2 receptors are expressed on osteoblasts (P2X2,5,6,7 and P2Y1,2,4,6). In the current study, we investigated complex interactions within the P2 receptor network using mathematical modeling. To characterize individual P2 receptors, we extracted data from published studies of overexpressed human and rodent (rat and mouse) receptors and fit their dependencies on ATP concentration using the Hill equation. Next, we examined responses induced by an ensemble of endogenously expressed P2 receptors. Murine osteoblastic cells (MC3T3-E1 cells) were loaded with fluo-4 and stimulated with varying concentrations of extracellular ATP. Elevations in the concentration of cytosolic free calcium ([Ca²⁺]_i) were monitored by confocal microscopy. Dependence of the calcium response on ATP concentration exhibited a complex pattern that was not explained by the simple addition of individual receptor responses. Fitting the experimental data with a combination of Hill equations from individual receptors revealed that P2Y1 and P2X7 mediated the rise in [Ca²⁺]_i at very low and high ATP concentrations, respectively. Interestingly, to describe responses at intermediate ATP concentrations, we had to assume that a receptor with a K_1∕2 in that range (e.g. P2Y4 or P2X5) exerts an inhibitory effect. This study provides new insights into the interactions among individual P2 receptors in producing an ensemble response to extracellular ATP.

• ATP
• Hill equation
• P2 receptor
• heterologous desensitization
• modeling
• osteoblast

Guanine-based purines (GBPs) have been recently proposed to be not only metabolic agents but also extracellular signaling molecules that regulate important functions in the central nervous system. In such way, GBPs-mediated neuroprotection, behavioral responses and neuronal plasticity have been broadly described in the literature. However, while a number of these functions (i.e., GBPs neurothophic effects) have been well-established, the molecular mechanisms behind these GBPs-dependent effects are still unknown. Furthermore, no plasma membrane receptors for GBPs have been described so far, thus GBPs are still considered orphan neuromodulators. Interestingly, an intricate and controversial functional interplay between GBPs effects and adenosine receptors activity has been recently described, thus triggering the hypothesis that GBPs mechanism of action might somehow involve adenosine receptors. Here, we review recent data describing the GBPs role in the brain. We focus on the involvement of GBPs regulating neuronal plasticity, and on the new hypothesis based on putative GBPs receptors. Overall, we expect to shed some light on the GBPs world since although these molecules might represent excellent candidates for certain neurological diseases management, the lack of putative GBPs receptors precludes any high throughput screening intent for the search of effective GBPs-based drugs.

• adenosine
• guanine-based purines
• guanosine
• neuroprotection
• purinergic receptors
• synaptic plasticity

P2X purinergic receptors are plasma membrane ATP-dependent cation channels that are broadly distributed in the mammalian tissues. P2RX2 is a modulator of auditory sensory hair cell mechanotransduction and plays an important role in hair cell tolerance to noise. In this study, we demonstrate for the first time in vitro and in cochlear neuroepithelium, that P2RX2 possesses the ATPase activity. We observed that the P2RX2 V60L human deafness mutation alters its ability to bind ATP, while the G353R has no effect on ATP binding or hydrolysis. A non-hydrolysable ATP assay using HEK293 cells suggests that ATP hydrolysis plays a significant role in the opening and gating of the P2RX2 ion channel. Moreover, the results of structural modeling of the molecule was in agreement with our experimental observations. These novel findings suggest the intrinsic ATPase activity of P2RX2 and provide molecular insights into the channel opening.

• ATPase activity
• Electrophysiology
• Ligand-gated ion channels
• P2X2
• computer modeling

• Astrocytes
• Brain ischemia
• Mitochondrion
• Neurons
• Neurotransmitters
• Receptors

• Adenosine Triphosphate/metabolism
• Cell Movement/physiology
• Cells, Cultured
• Humans
• Keratinocytes/metabolism
• Receptors, Purinergic P2Y/metabolism
• Signal Transduction/physiology
• Skin/cytology
• Wound Healing/physiology

• 82586 Wellcome Trust

• ATP
• Cell communication
• Messenger release
• Nucleotide signaling
• P2X receptor
• P2Y receptor

P2X receptors constitute a seven-member family (P2X1-7) of extracellular ATP-gated cation channels of widespread expression. Because P2X receptors have been implicated in neurological, inflammatory and cardiovascular diseases, they constitute promising drug targets. Since the first P2X cDNA sequences became available in 1994, numerous site-directed mutagenesis studies have been conducted to disclose key sites of P2X receptor function and oligomerization. The publication of the 3-Å crystal structures of the zebrafish P2X4 (zfP2X4) receptor in the homotrimeric apo-closed and ATP-bound open states in 2009 and 2012, respectively, has ushered a new era by allowing for the interpretation of the wealth of molecular data in terms of specific three-dimensional models and by paving the way for designing more-decisive experiments. Thanks to these structures, the last five years have provided invaluable insight into our understanding of the structure and function of the P2X receptor class of ligandgated ion channels. In this review, we provide an overview of mutagenesis studies of the pre- and post-crystal structure eras that identified amino acid residues of key importance for ligand binding, channel gating, ion flow, formation of the pore and the channel gate, and desensitization. In addition, the sites that are involved in the trimerization of P2X receptors are reviewed based on mutagenesis studies and interface contacts that were predicted by the zfP2X4 crystal structures.

• ANOVA, analysis of variance
• ATP, adenosine triphosphate sulfonic acid
• BBG, brilliant blue G
• Brilliant Blue G
• CNS, central nervous system
• CP, chronic pancreatitis
• Chronic Visceral Pain
• GAPDH, glyceraldehyde-3-phosphate dehydrogenase
• IT, intrathecal
• P2X7R, P2X7 receptor
• PBS, phosphate-buffered saline
• PCR, polymerase chain reaction
• Purinergic Receptors
• TBS, Tris-HCl buffer solution
• TNBS, trinitrobenzene sulfonic acid
• VFF, von Frey filament
• siRNA Knockdown
• siRNA, small-interfering RNA

• Adenosine 5′-triphosphate (ATP)
• Neurotransmission
• Noradrenaline
• P2 receptors
• Perivascular nerves
• Purines
• Sensory nerves
• Sympathetic nerves

• Baicalin
• P2X(3) receptor
• Superior cervical ganglia
• Sympathetic activity

• Adenosine Triphosphate/chemistry
• Adenosine Triphosphate/metabolism
• Animals
• Crystallography, X-Ray
• Humans
• Magnetic Resonance Spectroscopy
• Models, Molecular
• Protein Isoforms/chemistry
• Protein Isoforms/metabolism
• Protein Multimerization
• Protein Structure, Tertiary
• Receptors, Purinergic P2X/chemistry
• Receptors, Purinergic P2X/metabolism

P2X receptors are a family of trimeric ion channels that are gated by extracellular adenosine 5′-triphosphate (ATP). These receptors have long been a subject of intense research interest by virtue of their vital role in mediating the rapid and direct effects of extracellular ATP on membrane potential and cytosolic Ca²⁺ concentration, which in turn underpin the ability of ATP to regulate a diverse range of clinically significant physiological functions, including those associated with the cardiovascular, sensory, and immune systems. An important aspect of an ion channel's function is, of course, the means by which it transports ions across the biological membrane. A concerted effort by investigators over the last two decades has culminated in significant advances in our understanding of how P2X receptors conduct the inward flux of Na⁺ and Ca²⁺ in response to binding by ATP. However, this work has relied heavily on results from current recordings of P2X receptors altered by site-directed mutagenesis. In the absence of a 3-dimensional channel structure, this prior work provided only a vague and indirect appreciation of the relationship between structure, ion selectivity and flux. The recent publication of the crystal structures for both the closed and open channel conformations of the zebrafish P2X4 receptor has thus proved a significant boon, and has provided an important opportunity to overview the amassed functional data in the context of a working 3-dimensional model of a P2X receptor. In this paper, we will attempt to reconcile the existing functional data regarding ion permeation through P2X receptors with the available crystal structure data, highlighting areas of concordance and discordance as appropriate.

• ATP
• P2X
• SCAM
• gating
• mutagenesis
• permeability
• selectivity

Brain development requires the interaction of complex signaling pathways, involving different cell types and molecules. For a long time, most attention has focused on neurons in a neuronocentric conceptualization of central nervous system development, these cells fulfilling an intrinsic program that establishes the brain’s morphology and function. By contrast, glia have mainly been studied as support cells, offering guidance or as the cells that react to brain injury. However, new evidence is appearing that demonstrates a more fundamental role of glial cells in the control of different aspects of neuronal development and function, events in which the influence of neurons is at best weak. Moreover, it is becoming clear that the function and organization of the nervous system depends heavily on reciprocal neuron–glia interactions. During development, neurons are often generated far from their final destination and while intrinsic mechanisms are responsible for neuronal migration and growth, they need support and regulatory influences from glial cells in order to migrate correctly. Similarly, the axons emitted by neurons often have to reach faraway targets and in this sense, glia help define the way that axons grow. Moreover, oligodendrocytes and Schwann cells ultimately envelop axons, contributing to the generation of nodes of Ranvier. Finally, recent publications show that astrocytes contribute to the modulation of synaptic transmission. In this sense, purinergic receptors are expressed widely by glial cells and neurons, and recent evidence points to multiple roles of purines and purinergic receptors in neuronal development and function, from neurogenesis to axon growth and functional axonal maturation, as well as in pathological conditions in the brain. This review will focus on the role of glial and neuronal secreted purines, and on the purinergic receptors, fundamentally in the control of neuronal development and function, as well as in diseases of the nervous system.

• P2X
• P2Y
• axon
• axon growth
• neuron–glia interactions
• purinergic receptors

• Dorsal root ganglia
• Myocardial ischemic injury
• P2X(7) receptor
• Sensory-sympathetic coupling
• Stellate ganglia

• Analgesia
• Analgesics, Opioid/pharmacology
• Analgesics, Opioid/therapeutic use
• Animals
• Drug Tolerance/physiology
• Indoles/pharmacology
• Interleukin-18/metabolism
• Male
• Maleimides/pharmacology
• Morphine/pharmacology
• Morphine/therapeutic use
• Neuroglia/drug effects
• Neuroglia/metabolism
• Neurons/drug effects
• Neurons/metabolism
• Pain/drug therapy
• Pain/metabolism
• Pain Measurement
• Rats
• Rats, Sprague-Dawley
• Receptors, Interleukin-18/metabolism
• Receptors, Purinergic P2X7/metabolism
• Signal Transduction/drug effects
• Signal Transduction/physiology
• Spinal Cord/drug effects
• Spinal Cord/metabolism

A monolayer of endothelial cells (ECs) lines the lumen of blood vessels and forms a multifunctional transducing organ that mediates a plethora of cardiovascular processes. The activation of ECs from as state of quiescence is, therefore, regarded among the early events leading to the onset and progression of potentially lethal diseases, such as hypertension, myocardial infarction, brain stroke, and tumor. Intracellular Ca²⁺ signals have long been know to play a central role in the complex network of signaling pathways regulating the endothelial functions. Notably, recent work has outlined how any change in the pattern of expression of endothelial channels, transporters and pumps involved in the modulation of intracellular Ca²⁺ levels may dramatically affect whole body homeostasis. Vascular ECs may react to both mechanical and chemical stimuli by generating a variety of intracellular Ca²⁺ signals, ranging from brief, localized Ca²⁺ pulses to prolonged Ca²⁺ oscillations engulfing the whole cytoplasm. The well-defined spatiotemporal profile of the subcellular Ca²⁺ signals elicited in ECs by specific extracellular inputs depends on the interaction between Ca²⁺ releasing channels, which are located both on the plasma membrane and in a number of intracellular organelles, and Ca²⁺ removing systems. The present article aims to summarize both the past and recent literature in the field to provide a clear-cut picture of our current knowledge on the molecular nature and the role played by the components of the Ca²⁺ machinery in vascular ECs under both physiological and pathological conditions.

• Endothelial cells
• Ca²⁺ signalling
• Plasma membrane
• Endoplasmic reticulum
• Intracellular Ca²⁺ release
• Ca²⁺ entry
• Ca²⁺ removal
• Ca²⁺ oscillations

• Adenosine Triphosphate/metabolism
• Alanine/genetics
• Alanine/metabolism
• Amino Acid Substitution
• Animals
• Binding Sites
• Cells, Cultured
• HEK293 Cells
• Humans
• Kinetics
• Models, Molecular
• Mutation
• Nucleotides/genetics
• Nucleotides/metabolism
• Patch-Clamp Techniques
• Protein Structure, Tertiary
• Receptors, Purinergic P2X3/genetics
• Receptors, Purinergic P2X3/metabolism
• Receptors, Purinergic P2X4/genetics
• Receptors, Purinergic P2X4/metabolism
• Zebrafish

ATP-gated P2X receptors are trimeric ion channels that assemble as homo- or heteromers from seven cloned subunits. Transcripts and/or proteins of P2X subunits have been found in most, if not all, mammalian tissues and are being discovered in an increasing number of non-vertebrates. Both the first crystal structure of a P2X receptor and the generation of knockout (KO) mice for five of the seven cloned subtypes greatly advanced our understanding of their molecular and physiological function and their validation as drug targets. This review summarizes the current understanding of the structure and function of P2X receptors and gives an update on recent developments in the search for P2X subtype-selective ligands. It also provides an overview about the current knowledge of the regulation and modulation of P2X receptors on the cellular level and finally on their physiological roles as inferred from studies on KO mice.