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Horváth Á, Steib A, Nehr-Majoros A, Kántás B, Király Á, Racskó M, Tóth BI, Szánti-Pintér E, Kudová E, Skoda-Földes R, Helyes Z, Szőke É. Anti-Nociceptive Effects of Sphingomyelinase and Methyl-Beta-Cyclodextrin in the Icilin-Induced Mouse Pain Model. Int J Mol Sci 2024; 25:4637. [PMID: 38731855 PMCID: PMC11083984 DOI: 10.3390/ijms25094637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 05/13/2024] Open
Abstract
The thermo- and pain-sensitive Transient Receptor Potential Melastatin 3 and 8 (TRPM3 and TRPM8) ion channels are functionally associated in the lipid rafts of the plasma membrane. We have already described that cholesterol and sphingomyelin depletion, or inhibition of sphingolipid biosynthesis decreased the TRPM8 but not the TRPM3 channel opening on cultured sensory neurons. We aimed to test the effects of lipid raft disruptors on channel activation on TRPM3- and TRPM8-expressing HEK293T cells in vitro, as well as their potential analgesic actions in TRPM3 and TRPM8 channel activation involving acute pain models in mice. CHO cell viability was examined after lipid raft disruptor treatments and their effects on channel activation on channel expressing HEK293T cells by measurement of cytoplasmic Ca2+ concentration were monitored. The effects of treatments were investigated in Pregnenolone-Sulphate-CIM-0216-evoked and icilin-induced acute nocifensive pain models in mice. Cholesterol depletion decreased CHO cell viability. Sphingomyelinase and methyl-beta-cyclodextrin reduced the duration of icilin-evoked nocifensive behavior, while lipid raft disruptors did not inhibit the activity of recombinant TRPM3 and TRPM8. We conclude that depletion of sphingomyelin or cholesterol from rafts can modulate the function of native TRPM8 receptors. Furthermore, sphingolipid cleavage provided superiority over cholesterol depletion, and this method can open novel possibilities in the management of different pain conditions.
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Affiliation(s)
- Ádám Horváth
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary; (Á.H.); (A.S.); (A.N.-M.); (B.K.); (Á.K.); (Z.H.)
- Department of Pharmacology, Faculty of Pharmacy, University of Pécs, Rókus Str. 2., H-7624 Pécs, Hungary
| | - Anita Steib
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary; (Á.H.); (A.S.); (A.N.-M.); (B.K.); (Á.K.); (Z.H.)
| | - Andrea Nehr-Majoros
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary; (Á.H.); (A.S.); (A.N.-M.); (B.K.); (Á.K.); (Z.H.)
- National Laboratory for Drug Research and Development, Magyar Tudósok Cct. 2., H-1117 Budapest, Hungary
- Hungarian Research Network, Chronic Pain Research Group, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary
| | - Boglárka Kántás
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary; (Á.H.); (A.S.); (A.N.-M.); (B.K.); (Á.K.); (Z.H.)
- Department of Obstetrics and Gynaecology, University of Pécs, Édesanyák Str. 17., H-7624 Pécs, Hungary
| | - Ágnes Király
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary; (Á.H.); (A.S.); (A.N.-M.); (B.K.); (Á.K.); (Z.H.)
- National Laboratory for Drug Research and Development, Magyar Tudósok Cct. 2., H-1117 Budapest, Hungary
- Hungarian Research Network, Chronic Pain Research Group, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary
| | - Márk Racskó
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei Cct. 98., H-4032 Debrecen, Hungary; (M.R.); (B.I.T.)
| | - Balázs István Tóth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei Cct. 98., H-4032 Debrecen, Hungary; (M.R.); (B.I.T.)
| | - Eszter Szánti-Pintér
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo Namesti 2, 166 10 Prague, Czech Republic; (E.S.-P.); (E.K.)
| | - Eva Kudová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo Namesti 2, 166 10 Prague, Czech Republic; (E.S.-P.); (E.K.)
| | - Rita Skoda-Földes
- Institute of Chemistry, Department of Organic Chemistry, University of Pannonia, Egyetem Str. 10., H-8200 Veszprém, Hungary;
| | - Zsuzsanna Helyes
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary; (Á.H.); (A.S.); (A.N.-M.); (B.K.); (Á.K.); (Z.H.)
- National Laboratory for Drug Research and Development, Magyar Tudósok Cct. 2., H-1117 Budapest, Hungary
- Hungarian Research Network, Chronic Pain Research Group, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary
- PharmInVivo Ltd., Szondy György Str. 10., H-7629 Pécs, Hungary
| | - Éva Szőke
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary; (Á.H.); (A.S.); (A.N.-M.); (B.K.); (Á.K.); (Z.H.)
- National Laboratory for Drug Research and Development, Magyar Tudósok Cct. 2., H-1117 Budapest, Hungary
- Hungarian Research Network, Chronic Pain Research Group, University of Pécs, Szigeti Str. 12., H-7624 Pécs, Hungary
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Nehr-Majoros AK, Király Á, Helyes Z, Szőke É. Lipid raft disruption as an opportunity for peripheral analgesia. Curr Opin Pharmacol 2024; 75:102432. [PMID: 38290404 DOI: 10.1016/j.coph.2024.102432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 12/17/2023] [Accepted: 01/02/2024] [Indexed: 02/01/2024]
Abstract
Chronic pain conditions are unmet medical needs, since the available drugs, opioids, non-steroidal anti-inflammatory/analgesic drugs and adjuvant analgesics do not provide satisfactory therapeutic effect in a great proportion of patients. Therefore, there is an urgent need to find novel targets and novel therapeutic approaches that differ from classical pharmacological receptor antagonism. Most ion channels and receptors involved in pain sensation and processing such as Transient Receptor Potential ion channels, opioid receptors, P2X purinoreceptors and neurokinin 1 receptor are located in the lipid raft regions of the plasma membrane. Targeting the membrane lipid composition and structure by sphingolipid or cholesterol depletion might open future perspectives for the therapy of chronic inflammatory, neuropathic or cancer pain, most importantly acting at the periphery.
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Affiliation(s)
- Andrea Kinga Nehr-Majoros
- Department of Pharmacology and Pharmacotherapy, Medical School & Centre for Neuroscience, University of Pécs, 12 Szigeti Street, H-7624, Pécs, Hungary; National Laboratory for Drug Research and Development, Budapest, Hungary; Hungarian Research Network, Chronic Pain Research Group, Pécs, Hungary
| | - Ágnes Király
- Department of Pharmacology and Pharmacotherapy, Medical School & Centre for Neuroscience, University of Pécs, 12 Szigeti Street, H-7624, Pécs, Hungary; National Laboratory for Drug Research and Development, Budapest, Hungary; Hungarian Research Network, Chronic Pain Research Group, Pécs, Hungary
| | - Zsuzsanna Helyes
- Department of Pharmacology and Pharmacotherapy, Medical School & Centre for Neuroscience, University of Pécs, 12 Szigeti Street, H-7624, Pécs, Hungary; National Laboratory for Drug Research and Development, Budapest, Hungary; Hungarian Research Network, Chronic Pain Research Group, Pécs, Hungary
| | - Éva Szőke
- Department of Pharmacology and Pharmacotherapy, Medical School & Centre for Neuroscience, University of Pécs, 12 Szigeti Street, H-7624, Pécs, Hungary; National Laboratory for Drug Research and Development, Budapest, Hungary; Hungarian Research Network, Chronic Pain Research Group, Pécs, Hungary.
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Lalo U, Pankratov Y. ATP-mediated signalling in the central synapses. Neuropharmacology 2023; 229:109477. [PMID: 36841527 DOI: 10.1016/j.neuropharm.2023.109477] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 02/13/2023] [Accepted: 02/23/2023] [Indexed: 02/27/2023]
Abstract
ATP released from the synaptic terminals and astrocytes can activate neuronal P2 receptors at a variety of locations across the CNS. Although the postsynaptic ATP-mediated signalling does not bring a major contribution into the excitatory transmission, it is instrumental for slow and diffuse modulation of synaptic dynamics and neuronal firing in many CNS areas. Neuronal P2X and P2Y receptors can be activated by ATP released from the synaptic terminals, astrocytes and microglia and thereby can participate in the regulation of synaptic homeostasis and plasticity. There is growing evidence of importance of purinergic regulation of synaptic transmission in different physiological and pathological contexts. Here, we review the main mechanisms underlying the complexity and diversity of purinergic signalling and purinergic modulation in central neurons.
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Affiliation(s)
- Ulyana Lalo
- School of Life Sciences, University of Warwick, United Kingdom
| | - Yuriy Pankratov
- School of Life Sciences, University of Warwick, United Kingdom.
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Sivcev S, Kudova E, Zemkova H. Neurosteroids as positive and negative allosteric modulators of ligand-gated ion channels: P2X receptor perspective. Neuropharmacology 2023; 234:109542. [PMID: 37040816 DOI: 10.1016/j.neuropharm.2023.109542] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 03/06/2023] [Accepted: 04/07/2023] [Indexed: 04/13/2023]
Abstract
Neurosteroids are steroids synthesized de novo in the brain from cholesterol in an independent manner from peripheral steroid sources. The term "neuroactive steroid" includes all steroids independent of their origin, and newly synthesized analogs of neurosteroids that modify neuronal activities. In vivo application of neuroactive steroids induces potent anxiolytic, antidepressant, anticonvulsant, sedative, analgesic and amnesic effects, mainly through interaction with the γ-aminobutyric acid type-A receptor (GABAAR). However, neuroactive steroids also act as positive or negative allosteric regulators on several ligand-gated channels including N-methyl-d-aspartate receptors (NMDARs), nicotinic acetylcholine receptors (nAChRs) and ATP-gated purinergic P2X receptors. Seven different P2X subunits (P2X1-7) can assemble to form homotrimeric or heterotrimeric ion channels permeable for monovalent cations and calcium. Among them, P2X2, P2X4, and P2X7 are the most abundant within the brain and can be regulated by neurosteroids. Transmembrane domains are necessary for neurosteroid binding, however, no generic motif of amino acids can accurately predict the neurosteroid binding site for any of the ligand-gated ion channels including P2X. Here, we will review what is currently known about the modulation of rat and human P2X by neuroactive steroids and the possible structural determinants underlying neurosteroid-induced potentiation and inhibition of the P2X2 and P2X4 receptors.
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Affiliation(s)
- Sonja Sivcev
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic; Faculty of Science, Charles University, Prague, Czech Republic
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Hana Zemkova
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
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Roy A, Patra SK. Lipid Raft Facilitated Receptor Organization and Signaling: A Functional Rheostat in Embryonic Development, Stem Cell Biology and Cancer. Stem Cell Rev Rep 2023; 19:2-25. [PMID: 35997871 DOI: 10.1007/s12015-022-10448-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2022] [Indexed: 01/29/2023]
Abstract
Molecular views of plasma membrane organization and dynamics are gradually changing over the past fifty years. Dynamics of plasma membrane instigate several signaling nexuses in eukaryotic cells. The striking feature of plasma membrane dynamics is that, it is internally transfigured into various subdomains of clustered macromolecules. Lipid rafts are nanoscale subdomains, enriched with cholesterol and sphingolipids, reside as floating entity mostly on the exoplasmic leaflet of the lipid bilayer. In terms of functionality, lipid rafts are unique among other membrane subdomains. Herein, advances on the roles of lipid rafts in cellular physiology and homeostasis are discussed, precisely, on how rafts dynamically harbor signaling proteins, including GPCRs, catalytic receptors, and ionotropic receptors within it and orchestrate multiple signaling pathways. In the developmental proceedings signaling are designed for patterning of overall organism and they differ from the somatic cell physiology and signaling of fully developed organisms. Some of the developmental signals are characteristic in maintenance of stemness and activated during several types of tumor development and cancer progression. The harmony between extracellular signaling and lineage specific transcriptional programs are extremely important for embryonic development. The roles of plasma membrane lipid rafts mediated signaling in lineage specificity, early embryonic development, stem cell maintenance are emerging. In view of this, we have highlighted and analyzed the roles of lipid rafts in receptor organization, cell signaling, and gene expression during embryonic development; from pre-implantation through the post-implantation phase, in stem cell and cancer biology.
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Affiliation(s)
- Ankan Roy
- Epigenetics and Cancer Research Laboratory, Biochemistry and Molecular Biology Group, Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769008, India
| | - Samir Kumar Patra
- Epigenetics and Cancer Research Laboratory, Biochemistry and Molecular Biology Group, Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769008, India.
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Passarella D, Ronci M, Di Liberto V, Zuccarini M, Mudò G, Porcile C, Frinchi M, Di Iorio P, Ulrich H, Russo C. Bidirectional Control between Cholesterol Shuttle and Purine Signal at the Central Nervous System. Int J Mol Sci 2022; 23:ijms23158683. [PMID: 35955821 PMCID: PMC9369131 DOI: 10.3390/ijms23158683] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 12/07/2022] Open
Abstract
Recent studies have highlighted the mechanisms controlling the formation of cerebral cholesterol, which is synthesized in situ primarily by astrocytes, where it is loaded onto apolipoproteins and delivered to neurons and oligodendrocytes through interactions with specific lipoprotein receptors. The “cholesterol shuttle” is influenced by numerous proteins or carbohydrates, which mainly modulate the lipoprotein receptor activity, function and signaling. These molecules, provided with enzymatic/proteolytic activity leading to the formation of peptide fragments of different sizes and specific sequences, could be also responsible for machinery malfunctions, which are associated with neurological, neurodegenerative and neurodevelopmental disorders. In this context, we have pointed out that purines, ancestral molecules acting as signal molecules and neuromodulators at the central nervous system, can influence the homeostatic machinery of the cerebral cholesterol turnover and vice versa. Evidence gathered so far indicates that purine receptors, mainly the subtypes P2Y2, P2X7 and A2A, are involved in the pathogenesis of neurodegenerative diseases, such as Alzheimer’s and Niemann–Pick C diseases, by controlling the brain cholesterol homeostasis; in addition, alterations in cholesterol turnover can hinder the purine receptor function. Although the precise mechanisms of these interactions are currently poorly understood, the results here collected on cholesterol–purine reciprocal control could hopefully promote further research.
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Affiliation(s)
- Daniela Passarella
- Department of Medicine and Health Sciences “V. Tiberio”, University of Molise, 86100 Campobasso, Italy
| | - Maurizio Ronci
- Department of Pharmacy, University of Chieti-Pescara, 66100 Chieti, Italy
| | - Valentina Di Liberto
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, 90133 Palermo, Italy
| | - Mariachiara Zuccarini
- Department of Medical Oral and Biotechnological Sciences, University of Chieti-Pescara, 66100 Chieti, Italy
| | - Giuseppa Mudò
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, 90133 Palermo, Italy
| | - Carola Porcile
- Department of Medicine and Health Sciences “V. Tiberio”, University of Molise, 86100 Campobasso, Italy
| | - Monica Frinchi
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, 90133 Palermo, Italy
| | - Patrizia Di Iorio
- Department of Medical Oral and Biotechnological Sciences, University of Chieti-Pescara, 66100 Chieti, Italy
| | - Henning Ulrich
- Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-060, Brazil
| | - Claudio Russo
- Department of Medicine and Health Sciences “V. Tiberio”, University of Molise, 86100 Campobasso, Italy
- Correspondence: ; Tel.: +39-087-440-4897
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Wong J, Gu BJ, Teoh H, Krupa M, Monif M, Slee M, Wiley JS. Flow Cytometry Identifies an Early Stage of Platelet Apoptosis Produced by Agonists of the P2X1 and P2X7 Receptors. Platelets 2022; 33:621-631. [PMID: 35042433 DOI: 10.1080/09537104.2021.1981844] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Platelets express P2X1 receptors and our data also show the expression of P2X7 receptors. We studied the role of both receptors in platelet apoptosis by incubation of PRP with P2X agonists, then centrifuged to remove viable platelets, and analyzed the supernatant by flow cytometry to identify a sparse platelet-derived population that stained with MitoTracker dyes and CD41. BzATP, a potent agonist of P2X receptors, and ABT737, an activator of intrinsic apoptosis, produced altered platelets that stained moderately for annexin V and corresponded to an early stage apoptotic platelet (ESAP). Over a range of BzATP concentrations, we observed a dose-dependent formation of ESAPs between 5 and 500 uM BzATP, together with a variable formation of ESAPs at nanomolar ATP or BzATP (50-200 nM). Production of ESAPs occurred with αβ-meATP, while responses with either BzATP or αβ-meATP showed desensitization at a higher agonist concentration. Formation of ESAPs by either 100 nM or 0.5 mM BzATP was inhibited by preincubation of platelets with latrunculin A, an inhibitor of the actin cytoskeleton that prevents apoptosis. ESAP production was totally inhibited by preincubation of platelets with methyl-beta-cyclodextrin, which removes cholesterol from lipid rafts. Our data show that both P2X1 and P2X7 receptors are localized in platelet lipid rafts where P2X-agonists act to produce early stage apoptotic platelets.
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Affiliation(s)
- Joelyn Wong
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Ben J Gu
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Harry Teoh
- College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, Australia
| | - Malgorzata Krupa
- College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, Australia
| | - Mastura Monif
- Department of Neurology, Royal Melbourne Hospital, Parkville, Australia.,Department of Neuroscience, Monash University, Clayton, Australia
| | - Mark Slee
- College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, Australia
| | - James S Wiley
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.,Haematology Department, Box Hill Hospital, Australia
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Jonavičė U, Romenskaja D, Kriaučiūnaitė K, Jarmalavičiūtė A, Pajarskienė J, Kašėta V, Tunaitis V, Malm T, Giniatulin R, Pivoriūnas A. Extracellular Vesicles from Human Teeth Stem Cells Trigger ATP Release and Promote Migration of Human Microglia through P2X4 Receptor/MFG-E8-Dependent Mechanisms. Int J Mol Sci 2021; 22:ijms222010970. [PMID: 34681627 PMCID: PMC8537493 DOI: 10.3390/ijms222010970] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 10/07/2021] [Accepted: 10/09/2021] [Indexed: 11/16/2022] Open
Abstract
Extracellular vesicles (EVs) effectively suppress neuroinflammation and induce neuroprotective effects in different disease models. However, the mechanisms by which EVs regulate the neuroinflammatory response of microglia remains largely unexplored. Here, we addressed this issue by testing the action of EVs derived from human exfoliated deciduous teeth stem cells (SHEDs) on immortalized human microglial cells. We found that EVs induced a rapid increase in intracellular Ca2+ and promoted significant ATP release in microglial cells after 20 min of treatment. Boyden chamber assays revealed that EVs promoted microglial migration by 20%. Pharmacological inhibition of different subtypes of purinergic receptors demonstrated that EVs activated microglial migration preferentially through the P2X4 receptor (P2X4R) pathway. Proximity ligation and co-immunoprecipitation assays revealed that EVs promote association between milk fat globule-epidermal growth factor-factor VIII (MFG-E8) and P2X4R proteins. Furthermore, pharmacological inhibition of αVβ3/αVβ5 integrin suppressed EV-induced cell migration and formation of lipid rafts in microglia. These results demonstrate that EVs promote microglial motility through P2X4R/MFG-E8-dependent mechanisms. Our findings provide novel insights into the molecular mechanisms through which EVs target human microglia that may be exploited for the development of new therapeutic strategies targeting disease-associated neuroinflammation.
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Affiliation(s)
- Ugnė Jonavičė
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania; (U.J.); (D.R.); (K.K.); (A.J.); (J.P.); (V.K.); (V.T.)
| | - Diana Romenskaja
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania; (U.J.); (D.R.); (K.K.); (A.J.); (J.P.); (V.K.); (V.T.)
| | - Karolina Kriaučiūnaitė
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania; (U.J.); (D.R.); (K.K.); (A.J.); (J.P.); (V.K.); (V.T.)
| | - Akvilė Jarmalavičiūtė
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania; (U.J.); (D.R.); (K.K.); (A.J.); (J.P.); (V.K.); (V.T.)
| | - Justina Pajarskienė
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania; (U.J.); (D.R.); (K.K.); (A.J.); (J.P.); (V.K.); (V.T.)
| | - Vytautas Kašėta
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania; (U.J.); (D.R.); (K.K.); (A.J.); (J.P.); (V.K.); (V.T.)
| | - Virginijus Tunaitis
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania; (U.J.); (D.R.); (K.K.); (A.J.); (J.P.); (V.K.); (V.T.)
| | - Tarja Malm
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland; (T.M.); (R.G.)
| | - Rashid Giniatulin
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland; (T.M.); (R.G.)
| | - Augustas Pivoriūnas
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania; (U.J.); (D.R.); (K.K.); (A.J.); (J.P.); (V.K.); (V.T.)
- Correspondence:
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Regulation of P2X1 receptors by modulators of the cAMP effectors PKA and EPAC. Proc Natl Acad Sci U S A 2021; 118:2108094118. [PMID: 34508006 DOI: 10.1073/pnas.2108094118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2021] [Indexed: 11/18/2022] Open
Abstract
P2X1 receptors are adenosine triphosphate (ATP)-gated cation channels that are functionally important for male fertility, bladder contraction, and platelet aggregation. The activity of P2X1 receptors is modulated by lipids and intracellular messengers such as cAMP, which can stimulate protein kinase A (PKA). Exchange protein activated by cAMP (EPAC) is another cAMP effector; however, its effect on P2X1 receptors has not yet been determined. Here, we demonstrate that P2X1 currents, recorded from human embryonic kidney (HEK) cells transiently transfected with P2X1 cDNA, were inhibited by the highly selective EPAC activator 007-AM. In contrast, EPAC activation enhanced P2X2 current amplitude. The PKA activator 6-MB-cAMP did not affect P2X1 currents, but inhibited P2X2 currents. The inhibitory effects of EPAC on P2X1 were prevented by triple mutation of residues 21 to 23 on the amino terminus of P2X1 subunits to the equivalent amino acids on P2X2 receptors. Double mutation of residues 21 and 22 and single mutation of residue 23 also protected P2X1 receptors from inhibition by EPAC activation. Finally, the inhibitory effects of EPAC on P2X1 were also prevented by NSC23766, an inhibitor of Rac1, a member of the Rho family of small GTPases. These data suggest that EPAC is an important regulator of P2X1 and P2X2 receptors.
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Ferrari D, la Sala A, Milani D, Celeghini C, Casciano F. Purinergic Signaling in Controlling Macrophage and T Cell Functions During Atherosclerosis Development. Front Immunol 2021; 11:617804. [PMID: 33664731 PMCID: PMC7921745 DOI: 10.3389/fimmu.2020.617804] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 12/21/2020] [Indexed: 12/15/2022] Open
Abstract
Atherosclerosis is a hardening and narrowing of arteries causing a reduction of blood flow. It is a leading cause of death in industrialized countries as it causes heart attacks, strokes, and peripheral vascular disease. Pathogenesis of the atherosclerotic lesion (atheroma) relies on the accumulation of cholesterol-containing low-density lipoproteins (LDL) and on changes of artery endothelium that becomes adhesive for monocytes and lymphocytes. Immunomediated inflammatory response stimulated by lipoprotein oxidation, cytokine secretion and release of pro-inflammatory mediators, worsens the pathological context by amplifying tissue damage to the arterial lining and increasing flow-limiting stenosis. Formation of thrombi upon rupture of the endothelium and the fibrous cup may also occur, triggering thrombosis often threatening the patient’s life. Purinergic signaling, i.e., cell responses induced by stimulation of P2 and P1 membrane receptors for the extracellular nucleotides (ATP, ADP, UTP, and UDP) and nucleosides (adenosine), has been implicated in modulating the immunological response in atherosclerotic cardiovascular disease. In this review we will describe advancements in the understanding of purinergic modulation of the two main immune cells involved in atherogenesis, i.e., monocytes/macrophages and T lymphocytes, highlighting modulation of pro- and anti-atherosclerotic mediated responses of purinergic signaling in these cells and providing new insights to point out their potential clinical significance.
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Affiliation(s)
- Davide Ferrari
- Department of Life Science and Biotechnology, Section of Microbiology and Applied Pathology, University of Ferrara, Ferrara, Italy
| | - Andrea la Sala
- Certification Unit, Health Directorate, Bambino Gesù Pediatric Hospital, IRCCS, Rome, Italy
| | - Daniela Milani
- Department of Translational Medicine and LTTA Centre, University of Ferrara, Ferrara, Italy
| | - Claudio Celeghini
- Department of Translational Medicine and LTTA Centre, University of Ferrara, Ferrara, Italy
| | - Fabio Casciano
- Department of Translational Medicine and LTTA Centre, University of Ferrara, Ferrara, Italy
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11
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Sivcev S, Slavikova B, Ivetic M, Knezu M, Kudova E, Zemkova H. Lithocholic acid inhibits P2X2 and potentiates P2X4 receptor channel gating. J Steroid Biochem Mol Biol 2020; 202:105725. [PMID: 32652201 DOI: 10.1016/j.jsbmb.2020.105725] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 06/21/2020] [Accepted: 07/05/2020] [Indexed: 02/02/2023]
Abstract
The family of ATP-gated purinergic P2X receptors comprises seven bunits (P2X1-7) that are unevenly distributed in the central and peripheral nervous systems as well as other organs. Endogenous modulators of P2X receptors are phospholipids, steroids and neurosteroids. Here, we analyzed whether bile acids, which are natural products derived from cholesterol, affect P2X receptor activity. We examined the effects of primary and secondary bile acids and newly synthesized derivatives of lithocholic acid on agonist-induced responses in HEK293T cells expressing rat P2X2, P2X4 and P2X7 receptors. Electrophysiology revealed that low micromolar concentrations of lithocholic acid and its structural analog 4-dafachronic acid strongly inhibit ATP-stimulated P2X2 but potentiate P2X4 responses, whereas primary bile acids and other secondary bile acids exhibit no or reduced effects only at higher concentrations. Agonist-stimulated P2X7 responses are significantly potentiated by lithocholic acid at moderate concentrations. Structural modifications of lithocholic acid at positions C-3, C-5 or C-17 abolish both inhibitory and potentiation effects to varying degrees, and the 3α-hydroxy group contributes to the ability of the molecule to switch between potentiation and inhibition. Lithocholic acid allosterically modulates P2X2 and P2X4 receptor sensitivity to ATP, reduces the rate of P2X4 receptor desensitization and antagonizes the effect of ivermectin on P2X4 receptor deactivation. Alanine-scanning mutagenesis of the upper halve of P2X4 transmembrane domain-1 revealed that residues Phe48, Val43 and Tyr42 are important for potentiating effect of lithocholic acid, indicating that modulatory sites for lithocholic acid and ivermectin partly overlap. Lithocholic acid also inhibits ATP-evoked currents in pituitary gonadotrophs expressing native P2X2, and potentiates ATP currents in nonidentified pituitary cells expressing P2X4 receptors. These results indicate that lithocholic acid is a bioactive steroid that may help to further unveil the importance of the P2X2, and P2X4 receptors in many physiological processes.
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Affiliation(s)
- Sonja Sivcev
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic; Faculty of Science, Charles University, Prague, Czech Republic
| | - Barbora Slavikova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Milorad Ivetic
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic; Faculty of Science, Charles University, Prague, Czech Republic
| | - Michal Knezu
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic; Faculty of Science, Charles University, Prague, Czech Republic
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Hana Zemkova
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
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12
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Miller YI, Navia-Pelaez JM, Corr M, Yaksh TL. Lipid rafts in glial cells: role in neuroinflammation and pain processing. J Lipid Res 2020; 61:655-666. [PMID: 31862695 PMCID: PMC7193960 DOI: 10.1194/jlr.tr119000468] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/06/2019] [Indexed: 12/27/2022] Open
Abstract
Activation of microglia and astrocytes secondary to inflammatory processes contributes to the development and perpetuation of pain with a neuropathic phenotype. This pain state presents as a chronic debilitating condition and affects a large population of patients with conditions like rheumatoid arthritis and diabetes, or after surgery, trauma, or chemotherapy. Here, we review the regulation of lipid rafts in glial cells and the role they play as a key component of neuroinflammatory sensitization of central pain signaling pathways. In this context, we introduce the concept of an inflammaraft (i-raft), enlarged lipid rafts harboring activated receptors and adaptor molecules and serving as an organizing platform to initiate inflammatory signaling and the cellular response. Characteristics of the inflammaraft include increased relative abundance of lipid rafts in inflammatory cells, increased content of cholesterol per raft, and increased levels of inflammatory receptors, such as toll-like receptor (TLR)4, adaptor molecules, ion channels, and enzymes in lipid rafts. This inflammaraft motif serves an important role in the membrane assembly of protein complexes, for example, TLR4 dimerization. Operating within this framework, we demonstrate the involvement of inflammatory receptors, redox molecules, and ion channels in the inflammaraft formation and the regulation of cholesterol and sphingolipid metabolism in the inflammaraft maintenance and disruption. Strategies for targeting inflammarafts, without affecting the integrity of lipid rafts in noninflammatory cells, may lead to developing novel therapies for neuropathic pain states and other neuroinflammatory conditions.
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Affiliation(s)
- Yury I Miller
- Departments of MedicineUniversity of California San Diego, La Jolla, CA. mailto:
| | | | - Maripat Corr
- Departments of MedicineUniversity of California San Diego, La Jolla, CA
| | - Tony L Yaksh
- Anesthesiology,University of California San Diego, La Jolla, CA
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13
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Oxidized cholesterol species as signaling molecules in the brain: diabetes and Alzheimer's disease. Neuronal Signal 2019; 3:NS20190068. [PMID: 32269839 PMCID: PMC7104322 DOI: 10.1042/ns20190068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 01/16/2023] Open
Abstract
Type 2 diabetes is associated with adverse central nervous system effects, including a doubled risk for Alzheimer's disease (AD) and increased risk of cognitive impairment, but the mechanisms connecting diabetes to cognitive decline and dementia are unknown. One possible link between these diseases may be the associated alterations to cholesterol oxidation and metabolism in the brain. We will survey evidence demonstrating alterations to oxysterols in the brain in AD and diabetes and how these oxysterols could contribute to pathology, as well as identifying research questions that have not yet been addressed to allow for a fuller understanding of the role of oxysterols in AD and diabetes.
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14
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Liang X, Samways DSK, Cox J, Egan TM. Ca 2+ flux through splice variants of the ATP-gated ionotropic receptor P2X7 is regulated by its cytoplasmic N terminus. J Biol Chem 2019; 294:12521-12533. [PMID: 31248985 DOI: 10.1074/jbc.ra119.009666] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 06/26/2019] [Indexed: 01/12/2023] Open
Abstract
Activation of ionotropic P2X receptors increases free intracellular Ca2+ ([Ca2+] i ) by initiating a transmembrane cation flux. We studied the "a" and "k" splice variants of the rat purinergic P2X7 receptor (rP2X7aR and rP2X7kR) to exhibit a significant difference in Ca2+ flux through this channel. This difference is surprising because the variants share absolute sequence identity in the area of the pore that defines ionic selectivity. Here, we used patch-clamp fluorometry and chimeric receptors to show that the fraction of the total current carried by Ca2+ is a function of the primary sequence of the cytoplasmic N terminus. Using scanning mutagenesis, we identified five sites within the N terminus that respond to mutagenesis with a decrease in fractional calcium current and an increase in permeability to the polyatomic cation, N-methyl-d-glucamine (NMDG+), relative to Na+ (P NMDG/P Na). We tested the hypothesis that these sites line the permeation pathway by measuring the ability of thiol-reactive MTSET+ to alter the current of cysteine-substituted variants, but we detected no effect. Finally, we studied the homologous sites of the rat P2X2 receptor (rP2X2R) and observed that substitutions at Glu17 significantly reduced the fractional calcium current. Taken together, our results suggest that a change in the structure of the N terminus alters the ability of an intra-pore Ca2+ selectivity filter to discriminate among permeating cations. These results are noteworthy for two reasons: they identify a previously unknown outcome of mutagenesis of the N-terminal domain, and they suggest caution when assigning structure to function for truncated P2X receptors that lack a part of the N terminus.
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Affiliation(s)
- Xin Liang
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-Sen University, Guangzhou 510275, China
| | | | - Jane Cox
- Department of Pharmacology and Physiology and The Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri 63104
| | - Terrance M Egan
- Department of Pharmacology and Physiology and The Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri 63104.
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15
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Schmidt A, Alsop RJ, Rimal R, Lenzig P, Joussen S, Gervasi NN, Khondker A, Gründer S, Rheinstädter MC, Wiemuth D. Modulation of DEG/ENaCs by Amphiphiles Suggests Sensitivity to Membrane Alterations. Biophys J 2019; 114:1321-1335. [PMID: 29590590 DOI: 10.1016/j.bpj.2018.01.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 01/22/2018] [Accepted: 01/26/2018] [Indexed: 12/25/2022] Open
Abstract
The bile acid-sensitive ion channel is activated by amphiphilic substances such as bile acids or artificial detergents via membrane alterations; however, the mechanism of membrane sensitivity of the bile acid-sensitive ion channel is not known. It has also not been systematically investigated whether other members of the degenerin/epithelial Na+ channel (DEG/ENaC) gene family are affected by amphiphilic compounds. Here, we show that DEG/ENaCs ASIC1a, ASIC3, ENaC, and the purinergic receptor P2X2 are modulated by a large number of different, structurally unrelated amphiphilic substances, namely the detergents N-lauroylsarcosine, Triton X-100, and β-octylglucoside; the fenamate flufenamic acid; the antipsychotic drug chlorpromazine; the natural phenol resveratrol; the chili pepper compound capsaicin; the loop diuretic furosemide; and the antiarrythmic agent verapamil. We determined the modification of membrane properties using large-angle x-ray diffraction experiments on model lipid bilayers, revealing that the amphiphilic compounds are positioned in a characteristic fashion either in the lipid tail group region or in the lipid head group region, demonstrating that they perturbed the membrane structure. Collectively, our results show that DEG/ENaCs and structurally related P2X receptors are modulated by diverse amphiphilic molecules. Furthermore, they suggest alterations of membrane properties by amphiphilic compounds as a mechanism contributing to modulation.
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Affiliation(s)
- Axel Schmidt
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Rick J Alsop
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Rahul Rimal
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Pia Lenzig
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Sylvia Joussen
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Natalie N Gervasi
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Adree Khondker
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Stefan Gründer
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | | | - Dominik Wiemuth
- Institute of Physiology, RWTH Aachen University, Aachen, Germany.
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16
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Fryatt AG, Dayl S, Stavrou A, Schmid R, Evans RJ. Organization of ATP-gated P2X1 receptor intracellular termini in apo and desensitized states. J Gen Physiol 2019; 151:146-155. [PMID: 30626615 PMCID: PMC6363416 DOI: 10.1085/jgp.201812108] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 08/21/2018] [Accepted: 11/19/2018] [Indexed: 12/31/2022] Open
Abstract
The human P2X1 receptor (hP2X1R) is a trimeric ligand-gated ion channel opened by extracellular ATP. The intracellular amino and carboxyl termini play significant roles in determining the time-course and regulation of channel gating-for example, the C terminus regulates recovery from the desensitized state following agonist washout. This suggests that the intracellular regions of the channel have distinct structural features. Studies on the hP2X3R have shown that the intracellular regions associate to form a cytoplasmic cap in the open state of the channel. However, intracellular features could not be resolved in the agonist-free apo and ATP-bound desensitized structures. Here we investigate the organization of the intracellular regions of hP2X1R in the apo and ATP-bound desensitized states following expression in HEK293 cells. We couple cysteine scanning mutagenesis of residues R25-G30 and H355-R360 with the use of bi-functional cysteine reactive cross-linking compounds of different lengths (MTS-2-MTS, BMB, and BM(PEG)2), which we use as molecular calipers. If two cysteine residues come into close proximity, we predict they will be cross-linked and result in ∼66% of the receptor subunits running on a Western blot as dimers. In the control construct (C349A) that removed the free cysteine C349, and some cysteine-containing mutants, cross-linker treatment does not result in dimerization. However, we detect efficient dimerization for R25C, G30C, P358C, K359C, and R360C. This selective pattern indicates that there is structural organization to these regions in the apo and desensitized states in a native membrane environment. The existence of such precap (apo) and postcap (desensitized) organization of the intracellular domains would facilitate efficient gating of the channel.
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Affiliation(s)
- Alistair G Fryatt
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Sudad Dayl
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
- Department of Chemistry, College of Science, University of Baghdad, Baghdad, Iraq
| | - Anastasios Stavrou
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Ralf Schmid
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
- Leicester Institute of Structural and Chemical Biology, University of Leicester, Leicester, UK
| | - Richard J Evans
- Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
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17
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Schmid R, Evans RJ. ATP-Gated P2X Receptor Channels: Molecular Insights into Functional Roles. Annu Rev Physiol 2018; 81:43-62. [PMID: 30354932 DOI: 10.1146/annurev-physiol-020518-114259] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the nervous system, ATP is co-stored in vesicles with classical transmitters and released in a regulated manner. ATP from the intracellular compartment can also exit the cell through hemichannels and following shear stress or membrane damage. In the past 30 years, the action of ATP as an extracellular transmitter at cell-surface receptors has evolved from somewhat of a novelty that was treated with skepticism to purinergic transmission being accepted as having widespread important functional roles mediated by ATP-gated ionotropic P2X receptors (P2XRs). This review focuses on work published in the last five years and provides an overview of ( a) structural studies, ( b) the molecular basis of channel properties and regulation of P2XRs, and ( c) the physiological and pathophysiological roles of ATP acting at defined P2XR subtypes.
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Affiliation(s)
- Ralf Schmid
- Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, United Kingdom; .,Leicester Institute of Structural and Chemical Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Richard J Evans
- Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, United Kingdom;
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18
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刘 林, 魏 余, 刘 文, 孙 彤, 王 凯, 汪 颖, 李 宾. [Progress in the applications of high-speed atomic force microscopy in cell biology]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2018; 38:931-937. [PMID: 30187879 PMCID: PMC6744042 DOI: 10.3969/j.issn.1673-4254.2018.08.05] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Indexed: 12/24/2022]
Abstract
Without losing its high resolution, high-speed atomic force microscope (HS-AFM) represents a perfect combinationof scanning speed and precision and allows real-time and in situ observation of the dynamic processes in a biological system atboth the cellular and molecular levels. By combining the extremely high temporal resolution with the spatial resolution andcoupling with other advanced technologies, HS-AFM shows promising prospects for applications in life sciences such as cellbiology. In this review, we summarize the latest progress of HS-AFM in the field of cell biology, and discuss the impact ofenvironmental factors on conformation dynamics of DNA, the binding processes between DNA and protein, the domainchanges of membrane proteins, motility of myosin, and surface structure changes of living cells.
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Affiliation(s)
- 林 刘
- 中国科学院上海应用物理研究所物理生物研究室,上海 201800Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- 中国科学院大学,北京 100049University of Chinese Academy of Sciences, Beijing 100049, China
| | - 余辉 魏
- 中国科学院上海应用物理研究所物理生物研究室,上海 201800Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - 文静 刘
- 中国科学院上海应用物理研究所物理生物研究室,上海 201800Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- 中国科学院大学,北京 100049University of Chinese Academy of Sciences, Beijing 100049, China
| | - 彤 孙
- 中国科学院上海应用物理研究所物理生物研究室,上海 201800Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- 中国科学院大学,北京 100049University of Chinese Academy of Sciences, Beijing 100049, China
| | - 凯喆 王
- 中国科学院上海应用物理研究所物理生物研究室,上海 201800Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- 中国科学院大学,北京 100049University of Chinese Academy of Sciences, Beijing 100049, China
| | - 颖 汪
- 中国科学院上海应用物理研究所物理生物研究室,上海 201800Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - 宾 李
- 中国科学院上海应用物理研究所物理生物研究室,上海 201800Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
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19
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ATP-Gated P2X3 Receptors Are Specialised Sensors of the Extracellular Environment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018. [PMID: 28639246 DOI: 10.1007/5584_2017_56] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
P2X3 receptors are ion channels expressed by autonomic and sensory nerves and specialised in transducing extracellular ATP signals. Structural data, together with functional and biochemical studies, suggest that conformational changes of P2X3 receptors upon agonist binding influence downstream intracellular molecular mechanisms relevant for neuronal responses. Activity of P2X3 receptors is implicated in pain, itch, asthma, cardiovascular dysfunction and other pathologies. The study of these receptors has therefore a large potential in the field of drug development and interdisciplinary efforts could clarify molecular mechanisms controlling P2X3 receptor function in different physiological or pathological contexts.
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20
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Liu HY, Chen WL, Ober CK, Daniel S. Biologically Complex Planar Cell Plasma Membranes Supported on Polyelectrolyte Cushions Enhance Transmembrane Protein Mobility and Retain Native Orientation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:1061-1072. [PMID: 29020444 DOI: 10.1021/acs.langmuir.7b02945] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Reconstituted supported lipid bilayers (SLB) are widely used as in vitro cell-surface models because they are compatible with a variety of surface-based analytical techniques. However, one of the challenges of using SLBs as a model of the cell surface is the limited complexity in membrane composition, including the incorporation of transmembrane proteins and lipid diversity that may impact the activity of those proteins. Additionally, it is challenging to preserve the transmembrane protein native orientation, function, and mobility in SLBs. Here, we leverage the interaction between cell plasma membrane vesicles and polyelectrolyte brushes to create planar bilayers from cell plasma membrane vesicles that have budded from the cell surface. This approach promotes the direct incorporation of membrane proteins and other species into the planar bilayer without using detergent or reconstitution and preserves membrane constituents. Furthermore, the structure of the polyelectrolyte brush serves as a cushion between the planar bilayer and rigid supporting surface, limiting the interaction of the cytosolic domains of membrane proteins with this surface. Single particle tracking was used to analyze the motion of GPI-linked yellow fluorescent proteins (GPI-YFP) and neon-green fused transmembrane P2X2 receptors (P2X2-neon) and shows that this platform retains over 75% mobility of multipass transmembrane proteins in its native membrane environment. An enzyme accessibility assay confirmed that the protein orientation is preserved and results in the extracellular domain facing toward the bulk phase and the cytosolic side facing the support. Because the platform presented here retains the complexity of the cell plasma membrane and preserves protein orientation and mobility, it is a better representative mimic of native cell surfaces, which may find many applications in biological assays aimed at understanding cell membrane phenomena.
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Affiliation(s)
- Han-Yuan Liu
- Robert F. Smith School of Chemical and Biomolecular Engineering, ‡Department of Material Science and Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Wei-Liang Chen
- Robert F. Smith School of Chemical and Biomolecular Engineering, ‡Department of Material Science and Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Christopher K Ober
- Robert F. Smith School of Chemical and Biomolecular Engineering, ‡Department of Material Science and Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Susan Daniel
- Robert F. Smith School of Chemical and Biomolecular Engineering, ‡Department of Material Science and Engineering, Cornell University , Ithaca, New York 14853, United States
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21
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Murrell-Lagnado RD. Regulation of P2X Purinergic Receptor Signaling by Cholesterol. CURRENT TOPICS IN MEMBRANES 2017; 80:211-232. [PMID: 28863817 DOI: 10.1016/bs.ctm.2017.05.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
P2X receptors are cation-selective channels that are activated by the binding of extracellular ATP. They have a high permeability to Ca2+, Na+, and K+ and are expressed widely throughout the nervous, immune, cardiovascular, skeletal, gastrointestinal, respiratory, and endocrine systems. Seven mammalian subtypes of P2X receptor subunits have been identified, P2X1-7, and those that function as homotrimeric receptors (P2X1, 2, 3, 4, and 7) are targeted to lipid rafts, although they show limited resistance to solubilization by Triton X-100. Recent crystal structures of P2X3 and P2X4 receptors have provided considerable high-resolution information about the architecture of this family of receptors and yet the molecular details of how they are regulated by cholesterol are unknown. Currents mediated by the P2X1-4 receptors are either inhibited or relatively insensitive to cholesterol depletion, but there is no clear evidence to support the direct binding of cholesterol to these receptors. In contrast, the activity of the low-affinity, proinflammatory P2X7 receptor is potentiated by cholesterol depletion and regions within the proximal C-terminus play an important role in coupling changes in cholesterol to the gating of the pore. Based upon our understanding of the lipid signaling events that are triggered downstream of P2X7 receptor activation, a change in the levels of cholesterol may contribute to the sensitization of receptor currents and the dilation of the pore that occurs following prolonged, high-level stimulation. This chapter focuses on the regulation of P2X7 receptor signaling by cholesterol and our current understanding of the mechanisms that underlie this.
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Affiliation(s)
- Ruth D Murrell-Lagnado
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom.
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22
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Stokes L, Layhadi JA, Bibic L, Dhuna K, Fountain SJ. P2X4 Receptor Function in the Nervous System and Current Breakthroughs in Pharmacology. Front Pharmacol 2017; 8:291. [PMID: 28588493 PMCID: PMC5441391 DOI: 10.3389/fphar.2017.00291] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 05/05/2017] [Indexed: 12/18/2022] Open
Abstract
Adenosine 5′-triphosphate is a well-known extracellular signaling molecule and neurotransmitter known to activate purinergic P2X receptors. Information has been elucidated about the structure and gating of P2X channels following the determination of the crystal structure of P2X4 (zebrafish), however, there is still much to discover regarding the role of this receptor in the central nervous system (CNS). In this review we provide an overview of what is known about P2X4 expression in the CNS and discuss evidence for pathophysiological roles in neuroinflammation and neuropathic pain. Recent advances in the development of pharmacological tools including selective antagonists (5-BDBD, PSB-12062, BX430) and positive modulators (ivermectin, avermectins, divalent cations) of P2X4 will be discussed.
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Affiliation(s)
- Leanne Stokes
- School of Pharmacy, University of East Anglia, Norwich Research ParkNorwich, United Kingdom.,School of Biomedical and Health Sciences, RMIT University, BundooraVIC, Australia
| | - Janice A Layhadi
- Biomedical Research Centre, School of Biological Sciences, University of East AngliaNorwich, United Kingdom
| | - Lucka Bibic
- School of Pharmacy, University of East Anglia, Norwich Research ParkNorwich, United Kingdom
| | - Kshitija Dhuna
- School of Biomedical and Health Sciences, RMIT University, BundooraVIC, Australia
| | - Samuel J Fountain
- Biomedical Research Centre, School of Biological Sciences, University of East AngliaNorwich, United Kingdom
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23
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Mahaut-Smith MP, Taylor KA, Evans RJ. Calcium Signalling through Ligand-Gated Ion Channels such as P2X1 Receptors in the Platelet and other Non-Excitable Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:305-29. [PMID: 27161234 DOI: 10.1007/978-3-319-26974-0_13] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Ligand-gated ion channels on the cell surface are directly activated by the binding of an agonist to their extracellular domain and often referred to as ionotropic receptors. P2X receptors are ligand-gated non-selective cation channels with significant permeability to Ca(2+) whose principal physiological agonist is ATP. This chapter focuses on the mechanisms by which P2X1 receptors, a ubiquitously expressed member of the family of ATP-gated channels, can contribute to cellular responses in non-excitable cells. Much of the detailed information on the contribution of P2X1 to Ca(2+) signalling and downstream functional events has been derived from the platelet. The underlying primary P2X1-generated signalling event in non-excitable cells is principally due to Ca(2+) influx, although Na(+) entry will also occur along with membrane depolarization. P2X1 receptor stimulation can lead to additional Ca(2+) mobilization via a range of routes such as amplification of G-protein-coupled receptor-dependent Ca(2+) responses. This chapter also considers the mechanism by which cells generate extracellular ATP for autocrine or paracrine activation of P2X1 receptors. For example cytosolic ATP efflux can result from opening of pannexin anion-permeable channels or following damage to the cell membrane. Alternatively, ATP stored in specialised secretory vesicles can undergo quantal release via the process of exocytosis. Examples of physiological or pathophysiological roles of P2X1-dependent signalling in non-excitable cells are also discussed, such as thrombosis and immune responses.
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Affiliation(s)
- Martyn P Mahaut-Smith
- Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester, LE1 9HN, UK.
| | - Kirk A Taylor
- Department of Biomedical and Forensic Sciences, Anglia Ruskin University, Cambridge, UK
| | - Richard J Evans
- Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester, LE1 9HN, UK
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Marchenkova A, Vilotti S, Fabbretti E, Nistri A. Brain natriuretic peptide constitutively downregulates P2X3 receptors by controlling their phosphorylation state and membrane localization. Mol Pain 2015; 11:71. [PMID: 26576636 PMCID: PMC4650943 DOI: 10.1186/s12990-015-0074-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/03/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND ATP-gated P2X3 receptors are important transducers of nociceptive stimuli and are almost exclusively expressed by sensory ganglion neurons. In mouse trigeminal ganglion (TG), P2X3 receptor function is unexpectedly enhanced by pharmacological block of natriuretic peptide receptor-A (NPR-A), outlining a potential inhibitory role of endogenous natriuretic peptides in nociception mediated by P2X3 receptors. Lack of change in P2X3 protein expression indicates a complex modulation whose mechanisms for downregulating P2X3 receptor function remain unclear. RESULTS To clarify this process in mouse TG cultures, we suppressed NPR-A signaling with either siRNA of the endogenous agonist BNP, or the NPR-A blocker anantin. Thus, we investigated changes in P2X3 receptor distribution in the lipid raft membrane compartment, their phosphorylation state, as well as their function with patch clamping. Delayed onset of P2X3 desensitization was one mechanism for the anantin-induced enhancement of P2X3 activity. Anantin application caused preferential P2X3 receptor redistribution to the lipid raft compartment and decreased P2X3 serine phosphorylation, two phenomena that were not interdependent. An inhibitor of cGMP-dependent protein kinase and siRNA-mediated knockdown of BNP mimicked the effect of anantin. CONCLUSIONS We demonstrated that in mouse trigeminal neurons endogenous BNP acts on NPR-A receptors to determine constitutive depression of P2X3 receptor function. Tonic inhibition of P2X3 receptor activity by BNP/NPR-A/PKG pathways occurs via two distinct mechanisms: P2X3 serine phosphorylation and receptor redistribution to non-raft membrane compartments. This novel mechanism of receptor control might be a target for future studies aiming at decreasing dysregulated P2X3 receptor activity in chronic pain.
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Affiliation(s)
- Anna Marchenkova
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136, Trieste, Italy.
| | - Sandra Vilotti
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136, Trieste, Italy.
| | - Elsa Fabbretti
- Center for Biomedical Sciences and Engineering, University of Nova Gorica, 5000, Nova Gorica, Slovenia.
| | - Andrea Nistri
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136, Trieste, Italy.
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25
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Kuan SL, Wang T, Raabe M, Liu W, Lamla M, Weil T. Programming Bioactive Architectures with Cyclic Peptide Amphiphiles. Chempluschem 2015; 80:1347-1353. [PMID: 31973290 DOI: 10.1002/cplu.201500218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Indexed: 01/06/2023]
Abstract
We present a versatile approach for the synthesis of cyclic peptide amphiphiles of the hormone somatostatin (SST) with tunable lipophilic tails to program bioactive nanoarchitectures. A novel bis-alkylation reagent is synthesized that facilitates the functionalization of SST with a thiol anchor. Different hydrophobic moieties are introduced inspired by a biomimetic palmitoylation approach which opens access to cyclic peptide amphiphiles that display rich self-organization and cell membrane interactions.
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Affiliation(s)
- Seah Ling Kuan
- Institute of Organic Chemistry III-Macromolecular Chemistry & Biomaterials, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm (Germany)
| | - Tao Wang
- Institute of Organic Chemistry III-Macromolecular Chemistry & Biomaterials, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm (Germany)
| | - Marco Raabe
- Institute of Organic Chemistry III-Macromolecular Chemistry & Biomaterials, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm (Germany)
| | - Weina Liu
- Institute of Organic Chemistry III-Macromolecular Chemistry & Biomaterials, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm (Germany)
| | - Markus Lamla
- Institute of Organic Chemistry III-Macromolecular Chemistry & Biomaterials, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm (Germany)
| | - Tanja Weil
- Institute of Organic Chemistry III-Macromolecular Chemistry & Biomaterials, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm (Germany)
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26
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Pankratov Y, Lalo U. Role for astroglial α1-adrenoreceptors in gliotransmission and control of synaptic plasticity in the neocortex. Front Cell Neurosci 2015; 9:230. [PMID: 26136663 PMCID: PMC4468378 DOI: 10.3389/fncel.2015.00230] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 06/02/2015] [Indexed: 01/14/2023] Open
Abstract
Communication between neuronal and glial cells is thought to be very important for many brain functions. Acting via release of gliotransmitters, astrocytes can modulate synaptic strength. The mechanisms underlying gliotransmission remain uncertain with exocytosis being the most intriguing and debated pathway. We demonstrate that astroglial α1-adrenoreceptors are very sensitive to noradrenaline (NA) and make a significant contribution to intracellular Ca2+-signaling in layer 2/3 neocortical astrocytes. We also show that astroglial α1-adrenoreceptors are prone to desensitization upon prolonged exposure to NA. We show that within neocortical slices, α-1adrenoreceptors can activate vesicular release of ATP and D-serine from cortical astrocytes which initiate a burst of ATP receptor-mediated currents in adjacent pyramidal neurons. These purinergic currents can be inhibited by intracellular perfusion of astrocytes with Tetanus Toxin light chain, verifying their origin via astroglial exocytosis. We show that α1 adrenoreceptor-activated release of gliotransmitters is important for the induction of synaptic plasticity in the neocortex:long-term potentiation (LTP) of neocortical excitatory synaptic potentials can be abolished by the selective α1-adrenoreceptor antagonist terazosin. We show that weak sub-threshold theta-burst stimulation (TBS) can induce LTP when astrocytes are additionally activated by 1 μM NA. This facilitation is dependent on the activation of neuronal ATP receptors and is abolished in neocortical slices from dn-SNARE mice which have impaired glial exocytosis. Importantly, facilitation of LTP by NA can be significantly reduced by perfusion of individual astrocytes with Tetanus Toxin. Our results strongly support the physiological importance of astroglial adrenergic signaling and exocytosis of gliotransmitters for modulation of synaptic transmission and plasticity.
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Affiliation(s)
- Yuriy Pankratov
- School of Life Sciences, Gibbet Hill Campus, University of Warwick Coventry, UK
| | - Ulyana Lalo
- School of Life Sciences, Gibbet Hill Campus, University of Warwick Coventry, UK
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27
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Chen XQ, Zhu JX, Wang Y, Zhang X, Bao L. CaMKIIα and caveolin-1 cooperate to drive ATP-induced membrane delivery of the P2X3 receptor. J Mol Cell Biol 2015; 6:140-53. [PMID: 24755854 DOI: 10.1093/jmcb/mju011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The P2X3 receptor plays a vital role in sensory processing and transmission. The assembly and trafficking of the P2X3 receptor are important for its function in primary sensory neurons. As an important inflammation mediator, ATP is released from different cell types around primary sensory neurons, especially under pathological pain conditions. Here, we show that α, β-MeATP dramatically promoted membrane delivery of the P2X3 receptor both in HEK293T cells expressing recombinant P2X3 receptor and in rat primary sensory neurons. α, β-MeATP induced P2X3 receptor-mediated Ca²⁺ influx, which further activated Ca²⁺/calmodulin-dependent protein kinase IIα (CaMKIIα). The N terminus of the P2X3 receptor was responsible for CaMKIIα binding, whereas Thr³⁸⁸ in the C terminus was phosphorylated by CaMKIIα. Thr³⁸⁸ phosphorylation increased P2X3 receptor binding to caveolin-1. Caveolin-1 knockdown abrogated the α, β-MeATP-induced membrane insertion of the P2X3 receptor. Moreover, α, β-MeATP drove the CaMKIIα-mediated membrane coinsertion of the P2X2 receptor with the P2X3 receptor. The increased P2X3 receptors on the cell membrane that are due to Thr³⁸⁸ phosphorylation facilitated P2X3 receptor-mediated signal transduction. Together, our data indicate that CaMKIIα and caveolin-1 cooperate to drive ligand-induced membrane delivery of the P2X3 receptor and may provide a mechanism of P2X3 receptor sensitization in pain development.
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Affiliation(s)
- Xu-Qiao Chen
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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28
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Robinson LE, Shridar M, Smith P, Murrell-Lagnado RD. Plasma membrane cholesterol as a regulator of human and rodent P2X7 receptor activation and sensitization. J Biol Chem 2014; 289:31983-31994. [PMID: 25281740 PMCID: PMC4231676 DOI: 10.1074/jbc.m114.574699] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
P2X7 receptors are nonselective cation channels gated by high extracellular ATP, but with sustained activation, receptor sensitization occurs, whereby the intrinsic pore dilates, making the cell permeable to large organic cations, which eventually leads to cell death. P2X7 receptors associate with cholesterol-rich lipid rafts, but it is unclear how this affects the properties of the receptor channel. Here we show that pore-forming properties of human and rodent P2X7 receptors are sensitive to perturbations of cholesterol levels. Acute depletion of cholesterol with 5 mm methyl-β-cyclodextrin (MCD) caused a substantial increase in the rate of agonist-evoked pore formation, as measured by the uptake of ethidium dye, whereas cholesterol loading inhibited this process. Patch clamp analysis of P2X7 receptor currents carried by Na+ and N-methyl-d-glucamine (NMDG+) showed enhanced activation and current facilitation following cholesterol depletion. This contrasts with the inhibitory effect of methyl-β-cyclodextrin reported for other P2X subtypes. Mutational analysis suggests the involvement of an N-terminal region and a proximal C-terminal region that comprises multiple cholesterol recognition amino acid consensus (CRAC) motifs, in the cholesterol sensitivity of channel gating. These results reveal cholesterol as a negative regulator of P2X7 receptor pore formation, protecting cells from P2X7-mediated cell death.
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Affiliation(s)
- Lucy E Robinson
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Mitesh Shridar
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Philip Smith
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Ruth D Murrell-Lagnado
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
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29
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Kartz GA, Holme RL, Nicholson K, Sahoo D. SR-BI/CD36 chimeric receptors define extracellular subdomains of SR-BI critical for cholesterol transport. Biochemistry 2014; 53:6173-82. [PMID: 25211142 PMCID: PMC4188264 DOI: 10.1021/bi500706x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
High-density lipoproteins (HDLs) are athero-protective, primarily because of their ability to promote cholesterol flux from peripheral tissues to the liver by reverse cholesterol transport (RCT). The delivery of HDL-cholesteryl esters (CE) into cells is mediated by the HDL receptor, scavenger receptor class B type I (SR-BI), a promising target for enhancing whole body cholesterol disposal and preventing cardiovascular disease. A detailed understanding of the structural determinants underlying proper SR-BI/HDL alignment that supports the selective uptake of HDL-CE into cells remains lacking. To this end, we exploited CD36, a class B scavenger receptor with a predicted topology similar to that of SR-BI that binds HDL but is unable to mediate efficient selective uptake of HDL-CE. We generated a series of SR-BI/CD36 chimeric receptors that span the extracellular (EC) domain of SR-BI to delineate regions that are essential for SR-BI's cholesterol transport functions. All 16 SR-BI/CD36 chimeras were transiently expressed in COS-7 cells, and their plasma membrane localization was confirmed. The majority of SR-BI/CD36 chimeric receptors displayed significant reductions in their ability to (i) bind HDL, (ii) deliver HDL-CE to cells, (iii) mediate efflux of free cholesterol (FC) to HDL, and (iv) redistribute plasma membrane domains of FC. We also demonstrated that changes in SR-BI function were independent of receptor oligomerization. Altogether, we have identified discrete subdomains, particularly in the N-terminal and C-terminal regions of the EC domain of SR-BI, that are critical for productive receptor-ligand interactions and the various cholesterol transport functions of SR-BI.
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Affiliation(s)
- Gabriella A Kartz
- Departments of Pharmacology & Toxicology, ‡Biochemistry, and §Medicine, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
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30
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Pankratov Y, Lalo U. Calcium permeability of ligand-gated Ca2+ channels. Eur J Pharmacol 2014; 739:60-73. [DOI: 10.1016/j.ejphar.2013.11.017] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 10/22/2013] [Accepted: 11/07/2013] [Indexed: 11/28/2022]
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31
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Navarrete LC, Barrera NP, Huidobro-Toro JP. Vas deferens neuro-effector junction: from kymographic tracings to structural biology principles. Auton Neurosci 2014; 185:8-28. [PMID: 24956963 DOI: 10.1016/j.autneu.2014.05.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 05/14/2014] [Accepted: 05/20/2014] [Indexed: 11/29/2022]
Abstract
The vas deferens is a simple bioassay widely used to study the physiology of sympathetic neurotransmission and the pharmacodynamics of adrenergic drugs. The role of ATP as a sympathetic co-transmitter has gained increasing attention and furthered our understanding of its role in sympathetic reflexes. In addition, new information has emerged on the mechanisms underlying the storage and release of ATP. Both noradrenaline and ATP concur to elicit the tissue smooth muscle contractions following sympathetic reflexes or electrical field stimulation of the sympathetic nerve terminals. ATP and adenosine (its metabolic byproduct) are powerful presynaptic regulators of co-transmitter actions. In addition, neuropeptide Y, the third member of the sympathetic triad, is an endogenous modulator. The peptide plus ATP and/or adenosine play a significant role as sympathetic modulators of transmitter's release. This review focuses on the physiological principles that govern sympathetic co-transmitter activity, with special interest in defining the motor role of ATP. In addition, we intended to review the recent structural biology findings related to the topology of the P2X1R based on the crystallized P2X4 receptor from Danio rerio, or the crystallized adenosine A2A receptor as a member of the G protein coupled family of receptors as prototype neuro modulators. This review also covers structural elements of ectonucleotidases, since some members are found in the vas deferens neuro-effector junction. The allosteric principles that apply to purinoceptors are also reviewed highlighting concepts derived from receptor theory at the light of the current available structural elements. Finally, we discuss clinical applications of these concepts.
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Affiliation(s)
- L Camilo Navarrete
- Laboratorio de Estructura de Proteínas de Membrana y Señalización, Núcleo Milenio de Biología Estructural, NuBEs, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Chile
| | - Nelson P Barrera
- Laboratorio de Estructura de Proteínas de Membrana y Señalización, Núcleo Milenio de Biología Estructural, NuBEs, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Chile
| | - J Pablo Huidobro-Toro
- Laboratorio de Nucleótidos, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Chile.
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32
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Bernier LP, Ase AR, Séguéla P. Post-translational regulation of P2X receptor channels: modulation by phospholipids. Front Cell Neurosci 2013; 7:226. [PMID: 24324400 PMCID: PMC3838964 DOI: 10.3389/fncel.2013.00226] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 11/04/2013] [Indexed: 01/14/2023] Open
Abstract
P2X receptor channels mediate fast excitatory signaling by ATP and play major roles in sensory transduction, neuro-immune communication and inflammatory response. P2X receptors constitute a gene family of calcium-permeable ATP-gated cation channels therefore the regulation of P2X signaling is critical for both membrane potential and intracellular calcium homeostasis. Phosphoinositides (PIPn) are anionic signaling phospholipids that act as functional regulators of many types of ion channels. Direct PIPn binding was demonstrated for several ligand- or voltage-gated ion channels, however no generic motif emerged to accurately predict lipid-protein binding sites. This review presents what is currently known about the modulation of the different P2X subtypes by phospholipids and about critical determinants underlying their sensitivity to PIPn levels in the plasma membrane. All functional mammalian P2X subtypes tested, with the notable exception of P2X5, have been shown to be positively modulated by PIPn, i.e., homomeric P2X1, P2X2, P2X3, P2X4, and P2X7, as well as heteromeric P2X1/5 and P2X2/3 receptors. Based on various results reported on the aforementioned subtypes including mutagenesis of the prototypical PIPn-sensitive P2X4 and PIPn-insensitive P2X5 receptor subtypes, an increasing amount of functional, biochemical and structural evidence converges on the modulatory role of a short polybasic domain located in the proximal C-terminus of P2X subunits. This linear motif, semi-conserved in the P2X family, seems necessary and sufficient for encoding direct modulation of ATP-gated channels by PIPn. Furthermore, the physiological impact of the regulation of ionotropic purinergic responses by phospholipids on pain pathways was recently revealed in the context of native crosstalks between phospholipase C (PLC)-linked metabotropic receptors and P2X receptor channels in dorsal root ganglion sensory neurons and microglia.
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Affiliation(s)
- Louis-Philippe Bernier
- Department of Psychiatry, Brain Research Centre, University of British Columbia Vancouver, BC, Canada
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33
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Robinson LE, Murrell-Lagnado RD. The trafficking and targeting of P2X receptors. Front Cell Neurosci 2013; 7:233. [PMID: 24319412 PMCID: PMC3837535 DOI: 10.3389/fncel.2013.00233] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 11/07/2013] [Indexed: 01/01/2023] Open
Abstract
The functional expression of P2X receptors at the plasma membrane is dependent on their trafficking along secretory and endocytic pathways. There are seven P2X receptor subunits, and these differ in their subcellular distributions because they have very different trafficking properties. Some are retained within the endoplasmic reticulum (ER), while others are predominantly at the cell surface or within endosomes and lysosomes. Changes in recruitment of receptors to and from the plasma membrane provides a way of rapidly up- or down-regulating the cellular response to adenosine triphosphate (ATP). An additional layer of regulation is the targeting of these receptors within the membranes of each compartment, which affects their stability, function and the nature of the effector proteins with which they form signaling complexes. The trafficking and targeting of P2X receptors is regulated by their interactions with other proteins and with lipids and we can expect this to vary in a cell-type specific manner and in response to changes in the environment giving rise to differences in receptor activity and function.
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Affiliation(s)
- Lucy E Robinson
- Department of Pharmacology, University of Cambridge Cambridge, UK
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34
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Statins impair glucose uptake in tumor cells. Neoplasia 2012; 14:311-23. [PMID: 22577346 DOI: 10.1593/neo.12444] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Revised: 03/22/2012] [Accepted: 03/22/2012] [Indexed: 01/31/2023] Open
Abstract
Statins, HMG-CoA reductase inhibitors, are used in the prevention and treatment of cardiovascular diseases owing to their lipid-lowering effects. Previous studies revealed that, by modulating membrane cholesterol content, statins could induce conformational changes in cluster of differentiation 20 (CD20) tetraspanin. The aim of the presented study was to investigate the influence of statins on glucose transporter 1 (GLUT1)-mediated glucose uptake in tumor cells. We observed a significant concentration- and time-dependent decrease in glucose analogs' uptake in several tumor cell lines incubated with statins. This effect was reversible with restitution of cholesterol synthesis pathway with mevalonic acid as well as with supplementation of plasma membrane with exogenous cholesterol. Statins did not change overall GLUT1 expression at neither transcriptional nor protein levels. An exploratory clinical trial revealed that statin treatment decreased glucose uptake in peripheral blood leukocytes and lowered (18)F-fluorodeoxyglucose ((18)F-FDG) uptake by tumor masses in a mantle cell lymphoma patient. A bioinformatics analysis was used to predict the structure of human GLUT1 and to identify putative cholesterol-binding motifs in its juxtamembrane fragment. Altogether, the influence of statins on glucose uptake seems to be of clinical significance. By inhibiting (18)F-FDG uptake, statins can negatively affect the sensitivity of positron emission tomography, a diagnostic procedure frequently used in oncology.
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35
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Lalo U, Jones S, Roberts JA, Mahaut-Smith MP, Evans RJ. Heat shock protein 90 inhibitors reduce trafficking of ATP-gated P2X1 receptors and human platelet responsiveness. J Biol Chem 2012; 287:32747-54. [PMID: 22851178 PMCID: PMC3463321 DOI: 10.1074/jbc.m112.376566] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We have used selective inhibitors to determine whether the molecular chaperone heat shock protein 90 (HSP90) has an effect on both recombinant and native human P2X1 receptors. P2X1 receptor currents in HEK293 cells were reduced by ∼70–85% by the selective HSP90 inhibitor geldanamycin (2 μm, 20 min). This was associated with a speeding in the time course of desensitization as well as a reduction in cell surface expression. Imaging in real time of photoactivatable GFP-tagged P2X receptors showed that they are highly mobile. Geldanamycin almost abolished this movement for P2X1 receptors but had no effect on P2X2 receptor trafficking. P2X1/2 receptor chimeras showed that the intracellular N and C termini were involved in geldanamycin sensitivity. Geldanamycin also inhibited native P2X1 receptor-mediated responses. Platelet P2X1 receptors play an important role in hemostasis, contribute to amplification of signaling to a range of stimuli including collagen, and are novel targets for antithrombotic therapies. Platelet P2X1 receptor-, but not P2Y1 receptor-, mediated increases in intracellular calcium were reduced by 40–45% following HSP90 inhibition with geldanamycin or radicicol. Collagen stimulation leads to ATP release from platelets, and calcium increases to low doses of collagen were also reduced by ∼40% by the HSP90 inhibitors consistent with an effect on P2X1 receptors. These studies suggest that HSP90 inhibitors may be as effective as selective antagonists in regulating platelet P2X1 receptors, and their potential effects on hemostasis should be considered in clinical studies.
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Affiliation(s)
- Ulyana Lalo
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester LE1 9HN, United Kingdom
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36
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Sebastião AM, Colino-Oliveira M, Assaife-Lopes N, Dias RB, Ribeiro JA. Lipid rafts, synaptic transmission and plasticity: impact in age-related neurodegenerative diseases. Neuropharmacology 2012; 64:97-107. [PMID: 22820274 DOI: 10.1016/j.neuropharm.2012.06.053] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 06/23/2012] [Accepted: 06/26/2012] [Indexed: 10/28/2022]
Abstract
The synapse is a crowded area. In the last years, the concept that proteins can be organized in different membrane domains according to their structure has emerged. Cholesterol-rich membrane domains, or lipid rafts, form an organized portion of the membrane that is thought to concentrate signaling molecules. Accumulating evidence has shown that both the pre-synaptic and post-synaptic sites are highly enriched in lipid rafts, which are likely to organize and maintain synaptic proteins in their precise localization. Here we review recent studies highlighting the importance of lipid rafts for synaptic function and plasticity, as well as their relevance for age or disease-related cognitive impairment. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
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Affiliation(s)
- Ana M Sebastião
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.
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37
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Neuronal P2X2 receptors are mobile ATP sensors that explore the plasma membrane when activated. J Neurosci 2012; 31:16716-30. [PMID: 22090499 DOI: 10.1523/jneurosci.3362-11.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
ATP-gated ionotropic P2X2 receptors are widely expressed in neurons. Although the electrophysiological properties of P2X2 receptors have been extensively studied, little is known about the plasma membrane lateral mobility of P2X2 receptors or whether receptor mobility is regulated by ATP. Here we used single-molecule imaging with simultaneous whole-cell voltage-clamp recordings to track quantum dot-labeled P2X2 receptors in the dendrites of rat hippocampal neurons to explore P2X2 receptor mobility and its regulation. We find that plasma membrane P2X2 receptor lateral mobility in dendrites is heterogeneous but mostly Brownian in nature, consisting of mobile and slowly mobile receptor pools. Moreover, lateral mobility is P2X2 subunit and cell specific, is increased in an activation-dependent manner, and is regulated by cytosolic VILIP1, a calcium binding protein. Our data provide the first direct measures of P2X receptor mobility and show that P2X2 receptors are mobile ATP sensors, sampling more of the dendritic plasma membrane in response to ATP.
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38
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Fluvastatin suppresses native and recombinant human P2X4 receptor function. Purinergic Signal 2012; 8:311-6. [PMID: 22222818 DOI: 10.1007/s11302-011-9289-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 12/23/2011] [Indexed: 10/14/2022] Open
Abstract
Statins have both cholesterol lowering and anti-inflammatory activities, whether mechanisms underlying their activities are independent remains unclear. The ATP-gated P2X(4) receptor is a pro-inflammatory mediator. Here, we investigate the action of fluvastatin and other cholesterol depleting agents on native and recombinant human P2X(4) receptor. Fluvastatin and mβCD suppressed P2X(4)-dependent calcium influx in THP-1 monocytes, without affecting P2Y receptor responses. mβCD or filipin III suppressed the current density of recombinant human P2X(4) receptors. Human P2X(2) was insensitive to cholesterol depletion. Cholesterol depletion had no effect on intrinsic P2X(4) receptor properties as judged by ATP concentration-response relationship, receptor rundown or current decay during agonist occupancy. These data suggest fluvastatin suppresses P2X(4) activity in monocytes through cholesterol depletion and not by modulating intrinsic channel properties.
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Endosome-mediated retrograde axonal transport of P2X3 receptor signals in primary sensory neurons. Cell Res 2011; 22:677-96. [PMID: 22157653 DOI: 10.1038/cr.2011.197] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Neurotrophins and their receptors adopt signaling endosomes to transmit retrograde signals. However, the mechanisms of retrograde signaling for other ligand/receptor systems are poorly understood. Here, we report that the signals of the purinergic (P)2X(3) receptor, an ATP-gated ion channel, are retrogradely transported in dorsal root ganglion (DRG) neuron axons. We found that Rab5, a small GTPase, controls the early sorting of P2X(3) receptors into endosomes, while Rab7 mediates the fast retrograde transport of P2X(3) receptors. Intraplantar injection and axonal application into the microfluidic chamber of α, β-methylene-ATP (α, β-MeATP), a P2X selective agonist, enhanced the endocytosis and retrograde transport of P2X(3) receptors. The α, β-MeATP-induced Ca(2+) influx activated a pathway comprised of protein kinase C, rat sarcoma viral oncogene and extracellular signal-regulated protein kinase (ERK), which associated with endocytic P2X(3) receptors to form signaling endosomes. Disruption of the lipid rafts abolished the α, β-MeATP-induced ERK phosphorylation, endocytosis and retrograde transport of P2X(3) receptors. Furthermore, treatment of peripheral axons with α, β-MeATP increased the activation level of ERK and cAMP response element-binding protein in the cell bodies of DRG neurons and enhanced neuronal excitability. Impairment of either microtubule-based axonal transport in vivo or dynein function in vitro blocked α, β-MeATP-induced retrograde signals. These results indicate that P2X(3) receptor-activated signals are transmitted via retrogradely transported endosomes in primary sensory neurons and provide a novel signaling mechanism for ligand-gated channels.
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Chang TH, Segovia J, Sabbah A, Mgbemena V, Bose S. Cholesterol-rich lipid rafts are required for release of infectious human respiratory syncytial virus particles. Virology 2011; 422:205-13. [PMID: 22088217 DOI: 10.1016/j.virol.2011.10.029] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 10/24/2011] [Accepted: 10/28/2011] [Indexed: 11/26/2022]
Abstract
Cholesterol and sphingolipid enriched lipid raft micro-domains in the plasma membrane play an important role in the life-cycle of numerous enveloped viruses. Although human respiratory syncytial virus (RSV) proteins associate with the raft domains of infected cells and rafts are incorporated in RSV virion particles, the functional role of raft during RSV infection was unknown. In the current study we have identified rafts as an essential component of host cell that is required for RSV infection. Treatment of human lung epithelial cells with raft disrupting agent methyl-beta-cyclodextrin (MBCD) led to drastic loss of RSV infectivity due to diminished release of infectious progeny RSV virion particles from raft disrupted cells. RSV infection of raft deficient Niemann-Pick syndrome type C human fibroblasts and normal human embryonic lung fibroblasts revealed that during productive RSV infection, raft is required for release of infectious RSV particles.
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Affiliation(s)
- Te-Hung Chang
- Department of Microbiology & Immunology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Gnanasekaran A, Sundukova M, van den Maagdenberg AMJM, Fabbretti E, Nistri A. Lipid rafts control P2X3 receptor distribution and function in trigeminal sensory neurons of a transgenic migraine mouse model. Mol Pain 2011; 7:77. [PMID: 21958474 PMCID: PMC3193817 DOI: 10.1186/1744-8069-7-77] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 09/29/2011] [Indexed: 11/29/2022] Open
Abstract
Background A genetic knock-in mouse model expressing the R192Q mutation of the α1-subunit of the CaV2.1 channels frequently found in patients with familial hemiplegic migraine shows functional upregulation of ATP-sensitive P2X3 receptors of trigeminal sensory neurons that transduce nociceptive inputs to the brainstem. In an attempt to understand the basic mechanisms linked to the upregulation of P2X3 receptor activity, we investigated the influence of the lipid domain of these trigeminal sensory neurons on receptor compartmentalization and function. Results Knock-in neurons were strongly enriched with lipid rafts containing a larger fraction of P2X3 receptors at membrane level. Pretreatment with the CaV2.1 channel blocker ω-agatoxin significantly decreased the lipid raft content of KI membranes. After pharmacologically disrupting the cholesterol component of lipid rafts, P2X3 receptors became confined to non-raft compartments and lost their functional potentiation typically observed in KI neurons with whole-cell patch-clamp recording. Following cholesterol depletion, all P2X3 receptor currents decayed more rapidly and showed delayed recovery indicating that alteration of the lipid raft milieu reduced the effectiveness of P2X3 receptor signalling and changed their desensitization process. Kinetic modeling could reproduce the observed data when slower receptor activation was simulated and entry into desensitization was presumed to be faster. Conclusions The more abundant lipid raft compartment of knock-in neurons was enriched in P2X3 receptors that exhibited stronger functional responses. These results suggest that the membrane microenvironment of trigeminal sensory neurons is an important factor in determining sensitization of P2X3 receptors and could contribute to a migraine phenotype by enhancing ATP-mediated responses.
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Affiliation(s)
- Aswini Gnanasekaran
- Neurobiology Sector and Italian Institute of Technology Unit, International School for Advanced Studies, Trieste, Italy
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Coddou C, Yan Z, Obsil T, Huidobro-Toro JP, Stojilkovic SS. Activation and regulation of purinergic P2X receptor channels. Pharmacol Rev 2011; 63:641-83. [PMID: 21737531 DOI: 10.1124/pr.110.003129] [Citation(s) in RCA: 394] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mammalian ATP-gated nonselective cation channels (P2XRs) can be composed of seven possible subunits, denoted P2X1 to P2X7. Each subunit contains a large ectodomain, two transmembrane domains, and intracellular N and C termini. Functional P2XRs are organized as homomeric and heteromeric trimers. This review focuses on the binding sites involved in the activation (orthosteric) and regulation (allosteric) of P2XRs. The ectodomains contain three ATP binding sites, presumably located between neighboring subunits and formed by highly conserved residues. The detection and coordination of three ATP phosphate residues by positively charged amino acids are likely to play a dominant role in determining agonist potency, whereas an AsnPheArg motif may contribute to binding by coordinating the adenine ring. Nonconserved ectodomain histidines provide the binding sites for trace metals, divalent cations, and protons. The transmembrane domains account not only for the formation of the channel pore but also for the binding of ivermectin (a specific P2X4R allosteric regulator) and alcohols. The N- and C- domains provide the structures that determine the kinetics of receptor desensitization and/or pore dilation and are critical for the regulation of receptor functions by intracellular messengers, kinases, reactive oxygen species and mercury. The recent publication of the crystal structure of the zebrafish P2X4.1R in a closed state provides a major advance in the understanding of this family of receptor channels. We will discuss data obtained from numerous site-directed mutagenesis experiments accumulated during the last 15 years with reference to the crystal structure, allowing a structural interpretation of the molecular basis of orthosteric and allosteric ligand actions.
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Affiliation(s)
- Claudio Coddou
- Section on Cellular Signaling, Program in Developmental Neuroscience, National Institute of Child Health and Human Developmant, National Institutes of Health, Bethesda, MD 20892-4510, USA
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Lalo U, Roberts JA, Evans RJ. Identification of human P2X1 receptor-interacting proteins reveals a role of the cytoskeleton in receptor regulation. J Biol Chem 2011; 286:30591-30599. [PMID: 21757694 PMCID: PMC3162419 DOI: 10.1074/jbc.m111.253153] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
P2X1 receptors are ATP-gated ion channels expressed by smooth muscle and blood cells. Carboxyl-terminally His-FLAG-tagged human P2X1 receptors were stably expressed in HEK293 cells and co-purified with cytoskeletal proteins including actin. Disruption of the actin cytoskeleton with cytochalasin D inhibited P2X1 receptor currents with no effect on the time course of the response or surface expression of the receptor. Stabilization of the cytoskeleton with jasplakinolide had no effect on P2X1 receptor currents but decreased receptor mobility. P2X2 receptor currents were unaffected by cytochalasin, and P2X1/2 receptor chimeras were used to identify the molecular basis of actin sensitivity. These studies showed that the intracellular amino terminus accounts for the inhibitory effects of cytoskeletal disruption similar to that shown for lipid raft/cholesterol sensitivity. Stabilization of the cytoskeleton with jasplakinolide abolished the inhibitory effects of cholesterol depletion on P2X1 receptor currents, suggesting that lipid rafts may regulate the receptor through stabilization of the cytoskeleton. These studies show that the cytoskeleton plays an important role in P2X1 receptor regulation.
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Affiliation(s)
- Ulyana Lalo
- Department of Cell Physiology and Pharmacology, Henry Wellcome Building, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Jonathan A Roberts
- Department of Cell Physiology and Pharmacology, Henry Wellcome Building, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Richard J Evans
- Department of Cell Physiology and Pharmacology, Henry Wellcome Building, University of Leicester, Leicester LE1 9HN, United Kingdom.
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