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Cibelli A, Dohare P, Spray DC, Scemes E. Differential activation of mouse and human Panx1 channel variants. PLoS One 2023; 18:e0295710. [PMID: 38100403 PMCID: PMC10723736 DOI: 10.1371/journal.pone.0295710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/22/2023] [Indexed: 12/17/2023] Open
Abstract
Pannexins are ubiquitously expressed in human and mouse tissues. Pannexin 1 (Panx1), the most thoroughly characterized member of this family, forms plasmalemmal membrane channels permeable to relatively large molecules, such as ATP. Although human and mouse Panx1 amino acid sequences are conserved in the presently known regulatory sites involved in trafficking and modulation of the channel, differences are reported in the N- and C-termini of the protein, and the mechanisms of channel activation by different stimuli remain controversial. Here we used a neuroblastoma cell line to study the activation properties of endogenous mPanx1 and exogenously expressed hPanx1. Dye uptake and electrophysiological recordings revealed that in contrast to mouse Panx1, the human ortholog is insensitive to stimulation with high extracellular [K+] but responds similarly to activation of the purinergic P2X7 receptor. The two most frequent Panx1 polymorphisms found in the human population, Q5H (rs1138800) and E390D (rs74549886), exogenously expressed in Panx1-null N2a cells revealed that regarding P2X7 receptor mediated Panx1 activation, the Q5H mutant is a gain of function whereas the E390D mutant is a loss of function variant. Collectively, we demonstrate differences in the activation between human and mouse Panx1 orthologs and suggest that these differences may have translational implications for studies where Panx1 has been shown to have significant impact.
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Affiliation(s)
- Antonio Cibelli
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | - Preeti Dohare
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | - David C. Spray
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | - Eliana Scemes
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, New York, United States of America
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Zhang Y, Chen S, Luo L, Greenly S, Shi H, Xu JJ, Yan C. Role of cAMP in Cardiomyocyte Viability: Beneficial or Detrimental? Circ Res 2023; 133:902-923. [PMID: 37850368 PMCID: PMC10807647 DOI: 10.1161/circresaha.123.322652] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 10/10/2023] [Indexed: 10/19/2023]
Abstract
BACKGROUND 3', 5'-cyclic AMP (cAMP) regulates numerous cardiac functions. Various hormones and neurotransmitters elevate intracellular cAMP (i[cAMP]) in cardiomyocytes through activating GsPCRs (stimulatory-G-protein-coupled-receptors) and membrane-bound ACs (adenylyl cyclases). Increasing evidence has indicated that stimulating different GsPCRs and ACs exhibits distinct, even opposite effects, on cardiomyocyte viability. However, the underlying mechanisms are not fully understood. METHODS We used molecular and pharmacological approaches to investigate how different GsPCR/cAMP signaling differentially regulate cardiomyocyte viability with in vitro, ex vivo, and in vivo models. RESULTS For prodeath GsPCRs, we explored β1AR (beta1-adrenergic receptor) and H2R (histamine-H2-receptor). We found that their prodeath effects were similarly dependent on AC5 activation, ATP release to the extracellular space via PANX1 (pannexin-1) channel, and extracellular ATP (e[ATP])-mediated signaling involving in P2X7R (P2X purinoceptor 7) and CaMKII (Ca2+/calmodulin-dependent protein kinase II). PANX1 phosphorylation at Serine 206 by cAMP-dependent-PKA (protein-kinase-A) promoted PANX1 activation, which was critical in β1AR- or H2R-induced cardiomyocyte death in vitro and in vivo. β1AR or H2R was localized proximately to PANX1, which permits ATP release. For prosurvival GsPCRs, we explored adenosine-A2-receptor (A2R), CGRPR (calcitonin-gene-related-peptide-receptor), and RXFP1 (relaxin-family peptide-receptor 1). Their prosurvival effects were dependent on AC6 activation, cAMP efflux via MRP4 (multidrug resistance protein 4), extracellular cAMP metabolism to adenosine (e[cAMP]-to-e[ADO]), and e[ADO]-mediated signaling. A2R, CGRPR, or RXFP1 was localized proximately to MRP4, which enables cAMP efflux. Interestingly, exogenously increasing e[cAMP] levels by membrane-impermeable cAMP protected against cardiomyocyte death in vitro and in ex vivo and in vivo mouse hearts with ischemia-reperfusion injuries. CONCLUSIONS Our findings indicate that the functional diversity of different GsPCRs in cardiomyocyte viability could be achieved by their ability to form unique signaling complexes (signalosomes) that determine the fate of cAMP: either stimulate ATP release by activating PKA or directly efflux to be e[cAMP].
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Affiliation(s)
- Yishuai Zhang
- Aab Cardiovascular Research Institute, Department of Medicine
| | - Si Chen
- Aab Cardiovascular Research Institute, Department of Medicine
| | - Lingfeng Luo
- Aab Cardiovascular Research Institute, Department of Medicine
- Department of Biochemistry and Biophysics
| | - Sarah Greenly
- Aab Cardiovascular Research Institute, Department of Medicine
| | - Hangchuan Shi
- Department of Clinical and Translational Research
- Department of Public Health Sciences; University of Rochester School of Medicine and Dentistry, Rochester, NY 14642
| | | | - Chen Yan
- Aab Cardiovascular Research Institute, Department of Medicine
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3
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Obot P, Subah G, Schonwald A, Pan J, Velíšek L, Velíšková J, Stanton PK, Scemes E. Astrocyte and neuronal Panx1 support long-term reference memory in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.16.524236. [PMID: 36711845 PMCID: PMC9882221 DOI: 10.1101/2023.01.16.524236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Pannexin 1 (Panx1) are ubiquitously expressed proteins that form plasma membrane channels permeable to anions and moderate sized signaling molecules (e.g., ATP, glutamate). In the nervous system, activation of Panx1 channels have been extensively shown to contribute to distinct neurological disorders (epilepsy, chronic pain, migraine, neuroAIDS, etc.) but knowledge of extent to which these channels have a physiological role remains restricted to three studies supporting their involvement in hippocampus dependent learning. Given that Panx1 channels may provide an important mechanism for activity-dependent neuron-glia interaction, we used Panx1 transgenic mice with global and cell-type specific deletions of Panx1 to interrogate their participation in working and reference memory. Using the 8-arm radial maze, we show that long-term spatial reference memory, but not spatial working memory, is deficient in Panx1-null mice and that both astrocyte and neuronal Panx1 contribute to the consolidation of long-term spatial memory. Field potential recordings in hippocampal slices of Panx1-null mice revealed an attenuation of both long-term potentiation (LTP) of synaptic strength and long-term depression (LTD) at Schaffer collateral - CA1 synapses without alterations basal synaptic transmission or pre-synaptic paired-pulse facilitation. Our results implicate both neuronal and astrocyte Panx1 channels as critical players for the development and maintenance of long-term spatial reference memory in mice.
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Obot P, Subah G, Schonwald A, Pan J, Velíšek L, Velíšková J, Stanton PK, Scemes E. Astrocyte and Neuronal Panx1 Support Long-Term Reference Memory in Mice. ASN Neuro 2023; 15:17590914231184712. [PMID: 37365910 DOI: 10.1177/17590914231184712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023] Open
Abstract
Pannexin 1 (Panx1) is an ubiquitously expressed protein that forms plasma membrane channels permeable to anions and moderate-sized signaling molecules (e.g., ATP, glutamate). In the nervous system, activation of Panx1 channels has been extensively shown to contribute to distinct neurological disorders (epilepsy, chronic pain, migraine, neuroAIDS, etc.), but knowledge of the extent to which these channels have a physiological role remains restricted to three studies supporting their involvement in hippocampus dependent learning. Given that Panx1 channels may provide an important mechanism for activity-dependent neuron-glia interaction, we used Panx1 transgenic mice with global and cell-type specific deletions of Panx1 to interrogate their participation in working and reference memory. Using the eight-arm radial maze, we show that long-term spatial reference memory, but not spatial working memory, is deficient in Panx1-null mice and that both astrocyte and neuronal Panx1 contribute to the consolidation of long-term spatial memory. Field potential recordings in hippocampal slices of Panx1-null mice revealed an attenuation of both long-term potentiation (LTP) of synaptic strength and long-term depression (LTD) at Schaffer collateral-CA1 synapses without alterations of basal synaptic transmission or pre-synaptic paired-pulse facilitation. Our results implicate both neuronal and astrocyte Panx1 channels as critical players for the development and maintenance of long-term spatial reference memory in mice.
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Affiliation(s)
- Price Obot
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
- Department of Emergency Medicine, Penn State Hershey Medical Center, Hershey, PA, USA
| | - Galadu Subah
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
| | - Antonia Schonwald
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
| | - Jian Pan
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
| | - Libor Velíšek
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
- Department of Pediatrics, Penn State Hershey Medical Center, Hershey, PA, USA
- Department of Neurology, New York Medical College, Valhalla, NY, USA
| | - Jana Velíšková
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
- Department of Obstetrics and Gynecology, New York Medical College, Valhalla, NY, USA
| | - Patric K Stanton
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
- Department of Neurology, New York Medical College, Valhalla, NY, USA
| | - Eliana Scemes
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
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5
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Cibelli A, Scemes E, Spray DC. Activity and Stability of Panx1 Channels in Astrocytes and Neuroblastoma Cells Are Enhanced by Cholesterol Depletion. Cells 2022; 11:3219. [PMID: 36291086 PMCID: PMC9600160 DOI: 10.3390/cells11203219] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/01/2022] [Accepted: 10/11/2022] [Indexed: 11/17/2022] Open
Abstract
Pannexin1 (Panx1) is expressed in both neurons and glia where it forms ATP-permeable channels that are activated under pathological conditions such as epilepsy, migraine, inflammation, and ischemia. Membrane lipid composition affects proper distribution and function of receptors and ion channels, and defects in cholesterol metabolism are associated with neurological diseases. In order to understand the impact of membrane cholesterol on the distribution and function of Panx1 in neural cells, we used fluorescence recovery after photobleaching (FRAP) to evaluate its mobility and electrophysiology and dye uptake to assess channel function. We observed that cholesterol extraction (using methyl-β-cyclodextrin) and inhibition of its synthesis (lovastatin) decreased the lateral diffusion of Panx1 in the plasma membrane. Panx1 channel activity (dye uptake, ATP release and ionic current) was enhanced in cholesterol-depleted Panx1 transfected cells and in wild-type astrocytes compared to non-depleted or Panx1 null cells. Manipulation of cholesterol levels may, therefore, offer a novel strategy by which Panx1 channel activation might modulate various pathological conditions.
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Affiliation(s)
- Antonio Cibelli
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Eliana Scemes
- Department of Cell Biology and Anatomy, NY Medical College, Valhalla, NY10595, USA
| | - David C. Spray
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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de Lira MN, Bolini L, Amorim NRT, Silva-Souza HA, Diaz BL, Canetti C, Persechini PM, Bandeira-Melo C. Acute catabolism of leukocyte lipid bodies: Characterization of a nordihydroguaiaretic acid (NDGA)-induced proteasomal-dependent model. Prostaglandins Leukot Essent Fatty Acids 2021; 171:102320. [PMID: 34303171 DOI: 10.1016/j.plefa.2021.102320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/03/2021] [Accepted: 07/07/2021] [Indexed: 10/20/2022]
Abstract
Cytoplasmic availability of leukocyte lipid bodies is controlled by a highly regulated cycle of opposing biogenesis- and catabolism-related events. While leukocyte biogenic machinery is well-characterized, lipid body catabolic mechanisms are yet mostly unknown. Here, we demonstrated that nordihydroguaiaretic acid (NDGA) very rapidly decreases the numbers of pre-formed lipid bodies within lipid body-enriched cytoplasm of mouse leukocytes - macrophages, neutrophils and eosinophils. NDGA mechanisms driving leukocyte lipid body disappearance were not related to loss of cell viability, 5-lipoxygenase inhibition, ATP autocrine/paracrine activity, or biogenesis inhibition. Proteasomal-dependent breakdown of lipid bodies appears to control NDGA-driven leukocyte lipid body reduction, since it was Bortezomib-sensitive in macrophages, neutrophils and eosinophils. Our findings unveil an acute NDGA-triggered lipid body catabolic event - a novel experimental model for the still neglected research area on leukocyte lipid body catabolism, additionally favoring further insights on proteasomal contribution to lipid body breakdown.
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Affiliation(s)
- Maria N de Lira
- Laboratório de Inflamação, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Laboratório de Imunobiofisica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; BioMed X Institute (GmbH), Heidelberg, Germany
| | - Lukas Bolini
- Laboratório de Inflamação, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Natália R T Amorim
- Laboratório de Inflamação, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Hercules A Silva-Souza
- Laboratório de Imunobiofisica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Divisão de Verificação e Estudos Técnico-Científicos, Instituto Nacional de Metrologia Qualidade e Tecnologia, Duque de Caxias Rio de Janeiro, Brazil
| | - Bruno L Diaz
- Laboratório de Inflamação, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Claudio Canetti
- Laboratório de Inflamação, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pedro M Persechini
- Laboratório de Imunobiofisica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; This paper is dedicated to the memory of our dear colleague and friend Pedro M. Persechini, who passed prematurely and whose devotion to understanding the mechanisms of action of NDGA was unsurpassed
| | - Christianne Bandeira-Melo
- Laboratório de Inflamação, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
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Leonard EM, Zhang M, Nurse CA. Evidence for protein kinase involvement in the 5-HT-[Ca 2+ ] i -pannexin-1 signalling pathway in type II glial cells of the rat carotid body. Exp Physiol 2018; 104:244-253. [PMID: 30456914 DOI: 10.1113/ep087411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 11/19/2018] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? The mammalian carotid body (CB) is a peripheral chemoreceptor organ involved in O2 and CO2 /H+ homeostasis. Recent studies suggest that 5-HT, released from CB receptor cells, can stimulate adjacent glial-like type II cells, leading to an increase in intracellular Ca2+ (Δ[Ca2+ ]i ) and activation of ATP-permeable pannexin-1 (Panx-1) channels. The aim of this study was to elucidate the role of protein kinases in the 5-HT-[Ca2+ ]i -Panx-1 signalling pathway. What is the main finding and its importance? Src family kinase and protein kinase A, acting downstream from Δ[Ca2+ ]i , played central roles in 5-HT-mediated Panx-1 channel activation. This provides new insight into mechanisms regulating CB excitation, especially in pathophysiological conditions. ABSTRACT Chemoreceptor (type I) cells of the rodent carotid body (CB) synthesize and release several neurotransmitters/neuromodulators, including 5-hydroxytryptamine (5-HT), implicated in enhanced CB excitation after exposure to chronic intermittent hypoxia, e.g. sleep apnoea. However, recent studies suggest that 5-HT can robustly stimulate adjacent glial-like type II cells via ketanserin-sensitive 5-HT2 receptors, leading to intracellular Ca2+ elevation (Δ[Ca2+ ]i ) and activation of ATP-permeable pannexin-1 (Panx-1) channels. Using dissociated rat CB cultures, we investigated the role of protein kinases in the intracellular signalling pathways in type II cells. In isolated type II cells, 5-HT activated a Panx-1-like inward current (I5-HT ) that was reversibly inhibited by the Src family kinase inhibitor PP2 (1 μm), but not by its inactive analogue, PP3 (1 μm). Moreover, I5-HT was reversibly inhibited (>90%) by H89 (1 μm), a protein kinase A blocker, whereas the protein kinase C blocker GF109203X (2 μm) was largely ineffective. In contrast, the P2Y2R agonist UTP (100 μm) activated Panx-1-like currents that were reversibly inhibited (∼60%) by either H89 or GF109203X. Using fura-2 spectrofluorimetry, the 5-HT-induced Δ[Ca2+ ]i was unaffected by PP2, H89 and GF109293X, suggesting that the kinases acted downstream of the Ca2+ rise. Given that intracellular Ca2+ chelation was previously shown to block receptor-mediated Panx-1 current activation in type II cells, these data suggest that CB neuromodulators use overlapping, but not necessarily identical, signalling pathways to activate Panx-1 channels and release ATP, a CB excitatory neurotransmitter. In conclusion, these studies provide new mechanistic insight into 5-HT signalling in the CB that has pathophysiological relevance.
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Affiliation(s)
- Erin M Leonard
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Min Zhang
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Colin A Nurse
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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8
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Abstract
Adenosine triphosphate (ATP) has been well established as an important extracellular ligand of autocrine signaling, intercellular communication, and neurotransmission with numerous physiological and pathophysiological roles. In addition to the classical exocytosis, non-vesicular mechanisms of cellular ATP release have been demonstrated in many cell types. Although large and negatively charged ATP molecules cannot diffuse across the lipid bilayer of the plasma membrane, conductive ATP release from the cytosol into the extracellular space is possible through ATP-permeable channels. Such channels must possess two minimum qualifications for ATP permeation: anion permeability and a large ion-conducting pore. Currently, five groups of channels are acknowledged as ATP-release channels: connexin hemichannels, pannexin 1, calcium homeostasis modulator 1 (CALHM1), volume-regulated anion channels (VRACs, also known as volume-sensitive outwardly rectifying (VSOR) anion channels), and maxi-anion channels (MACs). Recently, major breakthroughs have been made in the field by molecular identification of CALHM1 as the action potential-dependent ATP-release channel in taste bud cells, LRRC8s as components of VRACs, and SLCO2A1 as a core subunit of MACs. Here, the function and physiological roles of these five groups of ATP-release channels are summarized, along with a discussion on the future implications of understanding these channels.
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9
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Scemes E, Velíšková J. Exciting and not so exciting roles of pannexins. Neurosci Lett 2017; 695:25-31. [PMID: 28284836 DOI: 10.1016/j.neulet.2017.03.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/02/2017] [Accepted: 03/06/2017] [Indexed: 01/24/2023]
Abstract
It is the current view that purinergic signaling regulates many physiological functions. Pannexin1 (Panx1), a member of the gap junction family of proteins is an ATP releasing channel that plays important physio-pathological roles in various tissues, including the CNS. Upon binding to purinergic receptors expressed in neural cells, ATP triggers cellular responses including increased cell proliferation, cell morphology changes, release of cytokines, and regulation of neuronal excitability via release of glutamate, GABA and ATP itself. Under pathological conditions such as ischemia, trauma, inflammation, and epilepsy, extracellular ATP concentrations increases drastically but the consequences of this surge is still difficult to characterize due to its rapid metabolism in ADP and adenosine, the latter having inhibitory action on neuronal activity. For seizures, for instance, the excitatory effect of ATP on neuronal activity is mainly related to its action of P2X receptors, while the inhibitory effects are related to activation of P1, adenosine receptors. Here we provide a mini review on the properties of pannexins with a main focus on Panx1 and its involvement in seizure activity. Although there are only few studies implicating Panx1 in seizures, they are illustrative of the dual role that Panx1 has on neuronal excitability.
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Affiliation(s)
- Eliana Scemes
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Jana Velíšková
- Departments of Cell Biology & Anatomy, Obstetrics & Gynecology and Neurology, New York Medical College, Valhalla, NY, 10595, USA.
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10
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Dahl G. ATP release through pannexon channels. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2014.0191. [PMID: 26009770 DOI: 10.1098/rstb.2014.0191] [Citation(s) in RCA: 170] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Extracellular adenosine triphosphate (ATP) serves as a signal for diverse physiological functions, including spread of calcium waves between astrocytes, control of vascular oxygen supply and control of ciliary beat in the airways. ATP can be released from cells by various mechanisms. This review focuses on channel-mediated ATP release and its main enabler, Pannexin1 (Panx1). Six subunits of Panx1 form a plasma membrane channel termed 'pannexon'. Depending on the mode of stimulation, the pannexon has large conductance (500 pS) and unselective permeability to molecules less than 1.5 kD or is a small (50 pS), chloride-selective channel. Most physiological and pathological stimuli induce the large channel conformation, whereas the small conformation so far has only been observed with exclusive voltage activation of the channel. The interaction between pannexons and ATP is intimate. The pannexon is not only the conduit for ATP, permitting ATP efflux from cells down its concentration gradient, but the pannexon is also modulated by ATP. The channel can be activated by ATP through both ionotropic P2X as well as metabotropic P2Y purinergic receptors. In the absence of a control mechanism, this positive feedback loop would lead to cell death owing to the linkage of purinergic receptors with apoptotic processes. A control mechanism preventing excessive activation of the purinergic receptors is provided by ATP binding (with low affinity) to the Panx1 protein and gating the channel shut.
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Affiliation(s)
- Gerhard Dahl
- School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
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Nosanchuk JD, Nosanchuk MD, Rodrigues ML, Nimrichter L, de Carvalho ACC, Weiss LM, Spray DC, Tanowitz HB. The Einstein-Brazil Fogarty: A decade of synergy. Braz J Microbiol 2015; 46:945-55. [PMID: 26691452 PMCID: PMC4704644 DOI: 10.1590/s1517-838246420140975] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 03/05/2015] [Indexed: 02/08/2023] Open
Abstract
A rich, collaborative program funded by the US NIH Fogarty program in 2004 has provided for a decade of remarkable opportunities for scientific advancement through the training of Brazilian undergraduate, graduate and postdoctoral students from the Federal University and Oswaldo Cruz Foundation systems at Albert Einstein College of Medicine. The focus of the program has been on the development of trainees in the broad field of Infectious Diseases, with a particular focus on diseases of importance to the Brazilian population. Talented trainees from various regions in Brazil came to Einstein to learn techniques and study fungal, parasitic and bacterial pathogens. In total, 43 trainees enthusiastically participated in the program. In addition to laboratory work, these students took a variety of courses at Einstein, presented their results at local, national and international meetings, and productively published their findings. This program has led to a remarkable synergy of scientific discovery for the participants during a time of rapid acceleration of the scientific growth in Brazil. This collaboration between Brazilian and US scientists has benefitted both countries and serves as a model for future training programs between these countries.
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Affiliation(s)
- Joshua D. Nosanchuk
- Departments of Medicine, Microbiology & Immunology, Albert
Einstein College of Medicine, Bronx, NY, EUA
- Send correspondence to J.D. Nosanchuk. Departments of Medicine,
Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, NY, EUA.
E-mail:
| | - Murphy D. Nosanchuk
- Departments of Medicine, Microbiology & Immunology, Albert
Einstein College of Medicine, Bronx, NY, EUA
- Instituto de Microbiologia Professor Paulo de Góes, Universidade
Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Marcio L. Rodrigues
- Instituto de Microbiologia Professor Paulo de Góes, Universidade
Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Centro de Desenvolvimento Tecnológico em Saúde, Fundação Oswaldo
Cruz, Rio de Janeiro, RJ, Brazil
| | - Leonardo Nimrichter
- Instituto de Microbiologia Professor Paulo de Góes, Universidade
Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | | | - Louis M. Weiss
- Departments of Pathology and Medicine, Albert Einstein College of
Medicine, Bronx, NY, EUA
| | - David C. Spray
- Departments of Neuroscience and Medicine, Albert Einstein College of
Medicine, Bronx, NY, EUA
| | - Herbert B. Tanowitz
- Departments of Pathology and Medicine, Albert Einstein College of
Medicine, Bronx, NY, EUA
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McNeill E, Crabtree MJ, Sahgal N, Patel J, Chuaiphichai S, Iqbal AJ, Hale AB, Greaves DR, Channon KM. Regulation of iNOS function and cellular redox state by macrophage Gch1 reveals specific requirements for tetrahydrobiopterin in NRF2 activation. Free Radic Biol Med 2015; 79:206-16. [PMID: 25451639 PMCID: PMC4344222 DOI: 10.1016/j.freeradbiomed.2014.10.575] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 10/20/2014] [Accepted: 10/20/2014] [Indexed: 01/08/2023]
Abstract
Inducible nitric oxide synthase (iNOS) is a key enzyme in the macrophage inflammatory response, which is the source of nitric oxide (NO) that is potently induced in response to proinflammatory stimuli. However, the specific role of NO production, as distinct from iNOS induction, in macrophage inflammatory responses remains unproven. We have generated a novel mouse model with conditional deletion of Gch1, encoding GTP cyclohydrolase 1 (GTPCH), an essential enzyme in the biosynthesis of tetrahydrobiopterin (BH4) that is a required cofactor for iNOS NO production. Mice with a floxed Gch1 allele (Gch1(fl/fl)) were crossed with Tie2cre transgenic mice, causing Gch1 deletion in leukocytes (Gch1(fl/fl)Tie2cre). Macrophages from Gch1(fl/fl)Tie2cre mice lacked GTPCH protein and de novo biopterin biosynthesis. When activated with LPS and IFNγ, macrophages from Gch1(fl/fl)Tie2cre mice induced iNOS protein in a manner indistinguishable from wild-type controls, but produced no detectable NO, as judged by L-citrulline production, EPR spin trapping of NO, and by nitrite accumulation. Incubation of Gch1(fl/fl)Tie2cre macrophages with dihydroethidium revealed significantly increased production of superoxide in the presence of iNOS expression, and an iNOS-independent, BH4-dependent increase in other ROS species. Normal BH4 levels, nitric oxide production, and cellular redox state were restored by sepiapterin, a precursor of BH4 production by the salvage pathway, demonstrating that the effects of BH4 deficiency were reversible. Gch1(fl/fl)Tie2cre macrophages showed only minor alterations in cytokine production and normal cell migration, and minimal changes in basal gene expression. However, gene expression analysis after iNOS induction identified 78 genes that were altered between wild-type and Gch1(fl/fl)Tie2cre macrophages. Pathway analysis identified decreased NRF2 activation, with reduced induction of archetypal NRF2 genes (gclm, prdx1, gsta3, nqo1, and catalase) in BH4-deficient Gch1(fl/fl)Tie2cre macrophages. These findings identify BH4-dependent iNOS regulation and NO generation as specific requirements for NRF2-dependent responses in macrophage inflammatory activation.
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Affiliation(s)
- Eileen McNeill
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, John Radcliffe Hospital, University of Oxford, Oxford, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Mark J Crabtree
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, John Radcliffe Hospital, University of Oxford, Oxford, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Natasha Sahgal
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Jyoti Patel
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, John Radcliffe Hospital, University of Oxford, Oxford, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Surawee Chuaiphichai
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, John Radcliffe Hospital, University of Oxford, Oxford, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Asif J Iqbal
- Sir William Dunn School of Pathology University of Oxford, Oxford, UK
| | - Ashley B Hale
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, John Radcliffe Hospital, University of Oxford, Oxford, UK; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - David R Greaves
- Sir William Dunn School of Pathology University of Oxford, Oxford, UK
| | - Keith M Channon
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, John Radcliffe Hospital, University of Oxford, Oxford, UK.
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