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Raza MZ, Cadassou O, Dumontet C, Cros-Perrial E, Jordheim LP. CD73 and cN-II regulate the cellular response to chemotherapeutic and hypoxic stress in lung adenocarcinoma cells. Biochim Biophys Acta Gen Subj 2021; 1865:129842. [PMID: 33434633 DOI: 10.1016/j.bbagen.2021.129842] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/08/2020] [Accepted: 01/04/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND Cytosolic 5'-nucleotidase II (cN-II) and ecto-5'-nucleotidase (CD73) are enzymes involved in the nucleotide metabolism by dephosphorylating nucleoside monophosphates. Both enzymes are involved in cancer by modifying anticancer drug activity, cancer cell biology and immune modulation. METHODS We have modified lung cancer cells (NCI-H292) to become deficient for either or both enzymes using the CRISPR/Cas9 technique, and studied the implication of the two enzymes in the cellular response to different stress condition i.e. chemotherapeutic agents, hypoxia and nucleotide stress. RESULTS Our results show that there is no significant role of these enzymes in cell proliferation under hypoxic stress. Similarly, cN-II and CD73 are not involved in wound healing ability under CoCl2-mediated HIF-1α stabilization. Furthermore, our results show that CD73-deficiency is associated with increased apoptosis in response to 1600 μM adenosine, decreased sensitivity to mitomycin and enhanced sensitivity to vincristine. cN-II deficiency increased in vivo tumor growth and sensitivity to vincristine and mitomycin C. CONCLUSIONS Our study gives new insights into the biological roles of cN-II and CD73 under stress conditions in this particular cancer cell line. Further experiments will help deciphering the molecular mechanisms underlying the observed differences.
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Affiliation(s)
- Muhammad-Zawwad Raza
- Univ Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France
| | - Octavia Cadassou
- Univ Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France
| | - Charles Dumontet
- Univ Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France; Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, F-69495 Pierre Bénite, France
| | - Emeline Cros-Perrial
- Univ Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France
| | - Lars Petter Jordheim
- Univ Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France.
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Bernareggi A, Luin E, Pavan B, Parato G, Sciancalepore M, Urbani R, Lorenzon P. Adenosine enhances acetylcholine receptor channel openings and intracellular calcium 'spiking' in mouse skeletal myotubes. Acta Physiol (Oxf) 2015; 214:467-80. [PMID: 25683861 DOI: 10.1111/apha.12473] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 10/23/2014] [Accepted: 02/11/2015] [Indexed: 12/26/2022]
Abstract
AIMS The autocrine activity of the embryonic isoform of the nicotinic acetylcholine receptor is crucial for the correct differentiation and trophism of skeletal muscle cells before innervation. The functional activity of extracellular adenosine and adenosine receptor subtypes expressed in differentiating myotubes is still unknown. In this study, we performed a detailed analysis of the role of adenosine receptor-mediated effects on the autocrine-mediated nicotinic acetylcholine receptor channel openings and the associated spontaneous intracellular calcium 'spikes' generated in differentiating mouse myotubes in vitro. METHODS Cell-attached patch-clamp recordings and intracellular calcium imaging experiments were performed in contracting myotubes derived from mouse satellite cells. RESULTS The endogenous extracellular adenosine and the adenosine receptor-mediated activity modulated the properties of the embryonic isoform of the nicotinic acetylcholine receptor in myotubes in vitro, by increasing the mean open time and the open probability of the ion channel, and sustaining nicotinic acetylcholine receptor-driven intracellular [Ca(2+) ]i 'spikes'. The pharmacological characterization of the adenosine receptor-mediated effects suggested a prevalent involvement of the A2B adenosine receptor subtype. CONCLUSION We propose that the interplay between endogenous adenosine and nicotinic acetylcholine receptors represents a potential novel strategy to improve differentiation/regeneration of skeletal muscle.
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Affiliation(s)
- A. Bernareggi
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
| | - E. Luin
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
| | - B. Pavan
- Department of Life Sciences and Biotechnology; University of Ferrara; Via L. Borsari 46 Ferrara I-44121 Italy
| | - G. Parato
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
| | - M. Sciancalepore
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
| | - R. Urbani
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
| | - P. Lorenzon
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
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Muller-Haegele S, Muller L, Whiteside TL. Immunoregulatory activity of adenosine and its role in human cancer progression. Expert Rev Clin Immunol 2014; 10:897-914. [DOI: 10.1586/1744666x.2014.915739] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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STRIEDINGER KATHARINE, MEDA PAOLO, SCEMES ELIANA. Exocytosis of ATP from astrocyte progenitors modulates spontaneous Ca2+ oscillations and cell migration. Glia 2007; 55:652-62. [PMID: 17309060 PMCID: PMC2617704 DOI: 10.1002/glia.20494] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the mature central nervous system (CNS) regulated secretion of ATP from astrocytes is thought to play a significant role in cell signaling. Whether such a mechanism is also operative in the developing nervous system and, if so, during which stage of development, has not been investigated. We have tackled this question using cells derived from reconstituted neurospheres, as well as brain explants of embryonic mice. Here, we show that in both models of neural cell development, astrocyte progenitors are competent for the regulated secretion of ATP-containing vesicles. We further document that this secretion is dependent on cytosolic Ca(2+) and the v-SNARE system, and takes place by exocytosis. Interference with ATP secretion alters spontaneous Ca(2+) oscillations and migration of neural progenitors. These data indicate that astrocyte progenitors acquire early in development the competence for regulated secretion of ATP, and that this event is implicated in the regulation of at least two cell functions, which are critical for the proper morphogenesis and functional maturation of the CNS.
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Affiliation(s)
| | - PAOLO MEDA
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - ELIANA SCEMES
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
- Correspondence to: Eliana Scemes, Department of Neuroscience, Kennedy Center, Room no. 203, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY 10461, USA. E-mail:
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Romanello M, Codognotto A, Bicego M, Pines A, Tell G, D'Andrea P. Autocrine/paracrine stimulation of purinergic receptors in osteoblasts: contribution of vesicular ATP release. Biochem Biophys Res Commun 2005; 331:1429-38. [PMID: 15883034 DOI: 10.1016/j.bbrc.2005.03.246] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Indexed: 11/26/2022]
Abstract
Extracellular nucleotides such as ATP and UTP are released in response to mechanical stimulation in different cell systems. It is becoming increasingly evident that ATP release plays a role in autocrine and paracrine stimulation of osteoblasts. Mechanical stimulation, as shear stress, membrane stretch or hypo-osmotic swelling, as well as oscillatory fluid flow, stimulates ATP release from different osteoblastic cell lines. Human osteoblast-like initial transfectant (HOBIT) cells release ATP in response to mechanical stimulation. In the present study, we show that HOBIT cells are activated by nanomolar levels of extracellular ATP, concentrations that can be detected under resting conditions and increase following hypotonic shock. Cell activation by hypotonic medium induced intracellular Ca2+ oscillations, and Egr-1 synthesis and DNA-binding activity. Quinacrine staining of living, resting cells revealed a granular fluorescence, typical of ATP-storing vesicles. Monensin prevented quinacrine staining and considerably inhibited hypotonic-induced ATP release. Finally, elevated levels of cytosolic Ca2+ activated massive ATP release and a dose-dependent loss of quinacrine granules. The contribution of a vesicular mechanism for ATP release is proposed to sustain paracrine osteoblast activation.
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Affiliation(s)
- Milena Romanello
- Department of Biochemistry, University of Trieste, via L. Giorgeri 1, 34100 Trieste, Italy
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Burrell HE, Wlodarski B, Foster BJ, Buckley KA, Sharpe GR, Quayle JM, Simpson AWM, Gallagher JA. Human keratinocytes release ATP and utilize three mechanisms for nucleotide interconversion at the cell surface. J Biol Chem 2005; 280:29667-76. [PMID: 15958381 DOI: 10.1074/jbc.m505381200] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Nucleotide activation of P2 receptors is important in autocrine and paracrine regulation in many tissues. In the epidermis, nucleotides are involved in proliferation, differentiation, and apoptosis. In this study, we have used a combination of luciferin-luciferase luminometry, pharmacological inhibitors, and confocal microscopy to demonstrate that HaCaT keratinocytes release ATP into the culture medium, and that there are three mechanisms for nucleotide interconversion, resulting in ATP generation at the cell surface. Addition of ADP, GTP, or UTP to culture medium elevated the ATP concentration. ADP to ATP conversion was inhibited by diadenosine pentaphosphate, oligomycin, and UDP, suggesting the involvement of cell surface adenylate kinase, F(1)F(0) ATP synthase, and nucleoside diphosphokinase (NDPK), respectively, which was supported by immunohistochemistry. Simultaneous addition of ADP and GTP elevated ATP above that for each nucleotide alone indicating that GTP acts as a phosphate donor. However, the activity of NDPK, F(1)F(0) ATP synthase or the forward reaction of adenylate kinase could not fully account for the culture medium ATP content. We postulate that this discrepancy is due to the reverse reaction of adenylate kinase utilizing AMP. In normal human skin, F(1)F(0) ATP synthase and NDPK were differentially localized, with mitochondrial expression in the basal layer, and cell surface expression in the differentiated layers. We and others have previously demonstrated that keratinocytes express multiple P2 receptors. In this study we now identify the potential sources of extracellular ATP required to activate these receptors and provide better understanding of the role of nucleotides in normal epidermal homeostasis and wound healing.
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Affiliation(s)
- Helen E Burrell
- Department of Human Anatomy & Cell Biology, School of Biomedical Sciences, University of Liverpool, The Sherrington Buildings, UK.
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7
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Release and extracellular metabolism of ATP by ecto-nucleotidase eNTPDase 1-3 in hypothalamic and pituitary cells. Purinergic Signal 2005; 1:135-44. [PMID: 18404498 PMCID: PMC2096527 DOI: 10.1007/s11302-005-6208-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Revised: 10/20/2004] [Accepted: 10/22/2004] [Indexed: 12/05/2022] Open
Abstract
Hypothalamic and pituitary cells express G protein-coupled adenosine and P2Y receptors and cation-conducting P2X receptor-channels, suggesting that extracellular ATP and other nucleotides may function as autocrine and/or paracrine signaling factors in these cells. Consistent with this hypothesis, we show that cultured normal and immortalized pituitary and hypothalamic cells release ATP under resting conditions. RT-PCR analysis also revealed the presence of transcripts for ecto-nucleotidase eNTPDase 1–2 in these cells. These enzymes were functional as documented by degradation of endogenously released and exogenously added ATP. Blocking the activity of eNTPDases by ARL67156 led to an increase in ATP release in perifused pituitary cells and inhibition of degradation of extracellularly added ATP. Furthermore, the addition of apyrase, a soluble ecto-nucleotidase, and the expression of recombinant mouse eNTPDase-2, enhanced degradation of both endogenously released and exogenously added ATP. The released ATP by resting hypothalamic cells was sufficient to activate and desensitize high-affinity recombinant P2X receptors, whereas facilitation of ATP metabolism by the addition of apyrase protected their desensitization. These results indicate that colocalization of ATP release sites and ecto-nucleotidase activity at the plasma membrane of hypothalamic and pituitary cells provides an effective mechanism for the operation of nucleotides as extracellular signaling molecules.
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Fellin T, Carmignoto G. Neurone-to-astrocyte signalling in the brain represents a distinct multifunctional unit. J Physiol 2004; 559:3-15. [PMID: 15218071 PMCID: PMC1665073 DOI: 10.1113/jphysiol.2004.063214] [Citation(s) in RCA: 206] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Astrocytes can respond to neurotransmitters released at the synapse by generating elevations in intracellular Ca(2+) concentration ([Ca(2+)](i)) and releasing glutamate that signals back to neurones. This discovery opens new perspectives for the possible participation of these glial cells in actual information processing by the brain and raises the hypothesis that astrocyte activation by neuronal signals plays a key role in distinct, functional events. Depending on the level of neuronal activity, the [Ca(2+)](i) response that is activated by neurotransmitters can either remain restricted to an astrocytic process or it can propagate as an intracellular [Ca(2+)](i) wave to other astrocytic processes in contact with different neurones, astrocytes, microglia or endothelial cells of cerebral arterioles. Glutamate release triggered by the [Ca(2+)](i) rise at the astrocytic process represents a feedback, short-distance signal that affects synaptic transmission locally. The release of glutamate as well as of other compounds far away from the site of initial activation represents a feedforward, long-distance signal that can be involved in the regulation of distinct processes. For instance, through the release of vasoactive molecules from the astrocytic processes in contact with cerebral arterioles, the neurone-astrocyte-endothelial cell signalling pathway plays a pivotal role in the neuronal control of vascular tone. In this article we will review recent results that should persuade us to reshape our current thinking on the roles of astroglial cells in the brain. We propose that neurones and astrocytes represent an integral unit that has a distinctive role in different fundamental events in brain function. Furthermore, while recent findings provide important evidences for the vesicular hypothesis of glutamate release, we discuss also the proposals for a possible physiological role of hemichannels and purinergic P2X(7) receptors in glutamate release from astrocytes. A full clarification of the functional significance of the bidirectional communication that astrocytes establish with neurones as well as with other brain cells represents one of the most intriguing challenges in neurobiological research at the moment and should fuel stimulating debates in years to come.
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Affiliation(s)
- Tommaso Fellin
- Istituto CNR di Neuroscienze and Dipartimento di Scienze Biomediche Sperimentali, Università di Padova, Viale G. Colombo 3, 35121 Padova, Italy
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9
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Joseph SM, Buchakjian MR, Dubyak GR. Colocalization of ATP release sites and ecto-ATPase activity at the extracellular surface of human astrocytes. J Biol Chem 2003; 278:23331-42. [PMID: 12684505 DOI: 10.1074/jbc.m302680200] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Extracellular ATP and other nucleotides function as autocrine and paracrine signaling factors in many tissues. Recent studies suggest that P2 nucleotide receptors and ecto-nucleotidases compete for a limited pool of endogenously released nucleotides within cell surface microenvironments that are functionally segregated from the bulk extracellular compartment. To test this hypothesis, we have used luciferase-based methods to continuously record extracellular ATP levels in monolayers of human 1321N1 astrocytoma cells under resting conditions, during stimulation of Ca2+-mobilizing receptors for thrombin or acetylcholine, and during mechanical stimulation by hypotonic stress. Soluble luciferase was utilized as an indicator of ATP levels within the bulk extracellular compartment, whereas a chimeric protein A-luciferase, adsorbed to antibodies against a glycosylphosphatidylinositol-anchored plasma membrane protein, was used as a spatially localized probe of ATP levels at the immediate extracellular surface. Significant accumulation of ATP in the bulk extracellular compartment, under either resting (1-2 nm ATP) or stimulated (10-80 nm ATP) conditions, was observed only when endogenous ecto-ATPase activity was pharmacologically inhibited by the poorly metabolizable analog, betagamma-methylene ATP. In contrast, accumulation of submicromolar ATP in the cell surface microenvironment was readily measured even in the absence of ecto-ATPase inhibition suggesting that the spatially colocalized luciferase could effectively compete with endogenous ecto-ATPases for released ATP. Other experiments revealed a critical role for elevated cytosolic [Ca2+] in the ATP release mechanism triggered by thrombin or muscarinic receptors but not in basal ATP release or release stimulated by hypotonic stress. These observations suggest that ATP release sites are colocalized with ecto-ATPases at the astrocyte cell surface. This colocalization may act to spatially restrict the actions of released ATP as a paracrine or autocrine mediator of cell-to-cell signaling.
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Affiliation(s)
- Sheldon M Joseph
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
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10
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Dubyak GR. Focus on "extracellular ATP signaling and P2X nucleotide receptors in monolayers of primary human vascular endothelial cells". Am J Physiol Cell Physiol 2002; 282:C242-4. [PMID: 11788334 DOI: 10.1152/ajpcell.00522.2001] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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11
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Roman RM, Feranchak AP, Salter KD, Wang Y, Fitz JG. Endogenous ATP release regulates Cl- secretion in cultured human and rat biliary epithelial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:G1391-400. [PMID: 10362642 DOI: 10.1152/ajpgi.1999.276.6.g1391] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
P2Y receptor stimulation increases membrane Cl- permeability in biliary epithelial cells, but the source of extracellular nucleotides and physiological relevance of purinergic signaling to biliary secretion are unknown. Our objectives were to determine whether biliary cells release ATP under physiological conditions and whether extracellular ATP contributes to cell volume regulation and transepithelial secretion. With the use of a sensitive bioluminescence assay, constitutive ATP release was detected from human Mz-ChA-1 cholangiocarcinoma cells and polarized normal rat cholangiocyte monolayers. ATP release increased rapidly during cell swelling induced by hypotonic exposure. In Mz-ChA-1 cells, removal of extracellular ATP (apyrase) and P2 receptor blockade (suramin) reversibly inhibited whole cell Cl- current activation and prevented cell volume recovery during hypotonic stress. Moreover, exposure to apyrase induced cell swelling under isotonic conditions. In intact normal rat cholangiocyte monolayers, hypotonic perfusion activated apical Cl- currents, which were inhibited by addition of apyrase and suramin to bathing media. These findings indicate that modulation of ATP release by the cellular hydration state represents a potential signal coordinating cell volume with membrane Cl- permeability and transepithelial Cl- secretion.
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Affiliation(s)
- R M Roman
- Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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12
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Roman RM, Fitz JG. Emerging roles of purinergic signaling in gastrointestinal epithelial secretion and hepatobiliary function. Gastroenterology 1999; 116:964-79. [PMID: 10092320 DOI: 10.1016/s0016-5085(99)70081-8] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- R M Roman
- Division of Gastroenterology, Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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Abstract
Through thin-section and freeze-fracture electron microscopy, we identify structural correlates of an intense vesicular traffic in a narrow band of cytoplasm around the cuticular plate of the bullfrog vestibular hair cells. Myriads of coated and uncoated vesicles associated with longitudinally oriented microtubules populate the narrow cytoplasmic region between the cuticular plate and the actin network of the apical junctional belt. If microtubules in the sensory hair cells, like those in axons, are pathways for organelle transport, then the characteristic distribution of microtubules around the cuticular plate represents transport pathways across the apical region of the hair cells. This compartmentalized membrane traffic system appears to support an intense vesicular release and uptake along a band of apical plasma membrane near the cell border. Functions of this transport system may include membrane recycling as well as exocytotic and endocytotic exchange between the hair cell cytoplasm and the endolymphatic compartment.
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Affiliation(s)
- B Kachar
- Section on Structural Cell Biology, National Institute on Deafness and other Communication Disorders (NIDCD), Bethesda, MD 20892, USA
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Vela JM, Dalmau I, González B, Castellano B. Morphology and distribution of microglial cells in the young and adult mouse cerebellum. J Comp Neurol 1995; 361:602-16. [PMID: 8576417 DOI: 10.1002/cne.903610405] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The morphology and distribution of microglial cells were studied in the normal cerebellum of young and adult mice using the histochemical demonstration of nucleoside diphosphatase as a specific microglial marker. Our results showed that microglial cells were present in all cerebellular lobules of both young and adult mice, but their distribution and morphology were not homogeneous throughout the cerebellum. Heterogeneity in microglial cell distribution was exclusively related to their location in the different histological layers, and no significant differences were found either between the different cerebellar lobules or between young and adult mice. Microglial density was higher in the cerebellar nuclei than in the cortex; within the cortex, the molecular layer was less densely populated by microglial cells than the granular layer and the white matter. The morphological study revealed that microglial cells were ramified in all cerebellar lobules of both young and adult mice but showed different sizes and ramification patterns as a function of their specific location in the different histological layers. Several typologies of microglial cells were described on the basis of observations in both horizontal and coronal sections. The specific layer-related pattern of microglial distribution and morphology in mouse cerebellum strongly suggests a physical and functional adaptation of these cells to the characteristics of their microenvironment.
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Affiliation(s)
- J M Vela
- Department of Cell Biology and Physiology, Faculty of Medicine, Autonomous University of Barcelona, Bellaterra, Spain
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15
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Liu P, Wen M, Hayashi J. Characterization of ATP receptor responsible for the activation of phospholipase A2 and stimulation of prostaglandin E2 production in thymic epithelial cells. Biochem J 1995; 308 ( Pt 2):399-404. [PMID: 7772019 PMCID: PMC1136939 DOI: 10.1042/bj3080399] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In TEA3A1 rat thymic epithelial cells, ATP stimulates prostaglandin E2 (PGE2) production through activation of phospholipase A2 (PLA2) enzymic activity. The stimulation of PGE2 production tested with other nucleotides indicated the agonist potency of adenosine 5'-[gamma-thio]triphosphate (ATP[S]) > or = UTP > ATP, with ED50 of about 10 microM for ATP[S]. In TEA3A1 cells, cross-linking studies with ATP[35S] revealed the presence of four cell-surface cross-linked bands of 42 kDa, 53 kDa, 83 kDa and 100 kDa in Triton X-100 extracts of TEA3A1 cells by fluorography. Guanosine 5'-[gamma-thio]triphosphate specifically blocked the cross-linking of ATP[35S] to the 53 kDa, 83 kDa and 100 kDa ATP-binding proteins, and inhibited the ATP[S]-mediated stimulation of PGE2 production with an ED50 of about 25 microM. On the other hand, 2-methylthioadenosine triphosphate (2MeSATP) blocked ATP[35S] cross-linking to the 42 kDa protein, but had no effect on ATP[S]-mediated stimulation of PGE2 production. In a variant cell line, TEAvarl, derived from TEA3A1 cells that lost their response to ATP in the activation of PLA2, the presence of 83 kDa ATP-binding protein was not detected. Results from our study suggest that ATP activates PLA2 enzymic activity in TEA3A1 cells by binding to an atypical ATP receptor that has not been described previously.
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Affiliation(s)
- P Liu
- W. Alton Jones Cell Science Center, Inc., Lake Placid, NY 12946, USA
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16
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Abstract
Catecholamine uptake into PC12 cells, in the presence and absence of ATP, was measured in a bicarbonate-buffered Krebs Ringer. ATP enhanced significantly the uptake in a dose-dependent manner with maximal uptake at 1-3 mM. ATP increased the Vmax of uptake by 3-5 fold for both dopamine and norepinephrine, without a significant change in the Km. ATP-stimulated amine uptake was temperature- and Na(+)-dependent and robust in bicarbonate, but not in HEPES buffer. The ability to enhance uptake was not observed with metabolites of ATP. GTP and UTP were equally effective to ATP in enhancing CA uptake. This uptake was less sensitive to uptake inhibitors in bicarbonate buffered media than in phosphate-buffered media, and more so in the presence of ATP. It is suggested that ATP is an allosteric modulator of the transporter and that a stable ATP analog, with ATP-like enhancement of dopamine uptake, may be an effective cocaine antagonist.
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Affiliation(s)
- A Eshleman
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore 21201, USA
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Salter MW, De Koninck Y, Henry JL. Physiological roles for adenosine and ATP in synaptic transmission in the spinal dorsal horn. Prog Neurobiol 1993; 41:125-56. [PMID: 8392739 DOI: 10.1016/0301-0082(93)90006-e] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- M W Salter
- Division of Neuroscience, Hospital for Sick Children, Toronto, Ontario, Canada
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Henning RH, Nelemans A, Houwertjes M, Agoston S. Reversal by suramin of neuromuscular block produced by pancuronium in the anaesthetized rat. Br J Pharmacol 1993; 108:717-20. [PMID: 8467359 PMCID: PMC1908058 DOI: 10.1111/j.1476-5381.1993.tb12867.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
1. Rats were anaesthetized with sodium pentobarbitone and maximal twitches of a tibialis anterior muscle were evoked by stimulation of the motor nerve. 2. Suramin, injected intravenously in a series of cumulative bolus doses, each 15 mg kg-1, completely reversed a 90% depression of twitches maintained by a continuous intravenous infusion of pancuronium. The cumulated dose necessary to restore twitches to 50% of their control amplitude was 35 mg kg-1. Suramin did not modify a similar degree of block produced by suxamethonium, nor did it affect the amplitude of control maximal twitches, even in cumulative doses up to 150 mg kg-1. 3. The effects of bolus doses of suramin (85 mg kg-1), neostigmine (0.03 mg kg-1) and 4-aminopyridine (1.2 mg kg-1), calculated to restore pancuronium-blocked twitches to 95% of control amplitude, were compared. Suramin produced the most rapid reversal (1.1 +/- 0.5 min), but its duration of action was the shortest (9.4 +/- 1.6 min). Suramin was without effect on heart rate or blood pressure in the doses used. 4. The results showed that suramin reversed neuromuscular block produced by nondepolarizing blocking drug, pancuronium, but was without effect on a block produced by the depolarizing blocking drug, suxamethonium. Its short duration of action suggests that suramin would probably not be of value clinically as a reversal agent. However, it is possible that it might serve as a starter compound for the synthesis and development of a new class of reversal agents for use in anaesthetic practice.
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Affiliation(s)
- R H Henning
- Department of Pharmacology/Clinical Pharmacology, University of Groningen, The Netherlands
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Henning RH, Nelemans A, Scaf AH, Van Eekeren J, Agoston S, Den Hertog A. Suramin reverses non-depolarizing neuromuscular blockade in rat diaphragm. Eur J Pharmacol 1992; 216:73-9. [PMID: 1326440 DOI: 10.1016/0014-2999(92)90211-l] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Unexpectedly, it was observed that the P2-purinoceptor antagonist, suramin (10 microM to 1 mM), reversed the muscle paralysis caused by structurally unrelated non-depolarizing relaxants. Suramin competitively reversed the blocking action of pancuronium. Both the pre- and postsynaptic blockade of nicotinic receptors by pancuronium was counteracted, as shown by the action of suramin, using train-of-four stimulation. Suramin did not affect the paralysis caused by the depolarizing relaxant, succinylcholine. The reversal action of suramin was not due to an increase in the acetylcholine concentration in the synaptic cleft, since neither the contraction of preparations partially paralysed by diminished acetylcholine release in the presence of low Ca2+ or high Mg2+ nor acetylcholinesterase activity were affected. Suramin did not affect the reduction in twitch tension caused by adenosine and potentiated the ATP-induced reduction in twitch, indicating that ATP-sensitive receptors are not involved in the reversal action of suramin. Consequently, these results suggest that the action of suramin is due to binding with a site on the acetylcholine receptor also occupied by non-depolarizing relaxants, but different from the site occupied by succinylcholine.
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Affiliation(s)
- R H Henning
- Department of Pharmacology/Clinical Pharmacology, University of Groningen, Netherlands
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