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Kostritskaia Y, Klüssendorf M, Pan YE, Hassani Nia F, Kostova S, Stauber T. Physiological Functions of the Volume-Regulated Anion Channel VRAC/LRRC8 and the Proton-Activated Chloride Channel ASOR/TMEM206. Handb Exp Pharmacol 2024; 283:181-218. [PMID: 37468723 DOI: 10.1007/164_2023_673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
Volume-regulated anion channels (VRACs) and the acid-sensitive outwardly rectifying anion channel (ASOR) mediate flux of chloride and small organic anions. Although known for a long time, they were only recently identified at the molecular level. VRACs are heteromers consisting of LRRC8 proteins A to E. Combining the essential LRRC8A with different LRRC8 paralogues changes key properties of VRAC such as conductance or substrate selectivity, which is how VRACs are involved in multiple physiological functions including regulatory volume decrease, cell proliferation and migration, cell death, purinergic signalling, fat and glucose metabolism, insulin signalling, and spermiogenesis. VRACs are also involved in pathological conditions, such as the neurotoxic release of glutamate and aspartate. Certain VRACs are also permeable to larger, organic anions, including antibiotics and anti-cancer drugs, making them an interesting therapeutic target. ASOR, also named proton-activated chloride channel (PAC), is formed by TMEM206 homotrimers on the plasma membrane and on endosomal compartments where it mediates chloride flux in response to extracytosolic acidification and plays a role in the shrinking and maturation of macropinosomes. ASOR has been shown to underlie neuronal swelling which causes cell death after stroke as well as promoting the metastasis of certain cancers, making them intriguing therapeutic targets as well.
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Affiliation(s)
- Yulia Kostritskaia
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Malte Klüssendorf
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Yingzhou Edward Pan
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Fatemeh Hassani Nia
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Simona Kostova
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Tobias Stauber
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany.
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Schachter J, Alvarez CL, Bazzi Z, Faillace MP, Corradi G, Hattab C, Rinaldi DE, Gonzalez-Lebrero R, Molineris MP, Sévigny J, Ostuni MA, Schwarzbaum PJ. Extracellular ATP hydrolysis in Caco-2 human intestinal cell line. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183679. [PMID: 34216588 DOI: 10.1016/j.bbamem.2021.183679] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/08/2021] [Accepted: 06/10/2021] [Indexed: 10/21/2022]
Abstract
Extracellular nucleotides and nucleosides activate signaling pathways that play major roles in the physiology and pathophysiology of the gastrointestinal tract. Ectonucleotidases hydrolyze extracellular nucleotides and thus regulate ligand exposure to purinergic receptors. In this study, we investigated the expression, localization and activities of ectonucleotidases using Caco-2 cells, a model of human intestinal epithelial cells. In addition, by studying ATP release and the rates of extracellular ATP (eATP) hydrolysis, we analyzed the contribution of these processes to the regulation of eATP in these cells. Results show that Caco-2 cells regulate the metabolism of eATP and by-products by ecto-nucleoside triphosphate diphosphohydrolase-1 and -2, a neutral ecto-phosphatase and ecto-5'-nucleotidase. All these ectoenzymes were kinetically characterized using intact cells, and their presence confirmed by denatured and native gels, western blot and cytoimmunofluorescence techniques. In addition, regulation of eATP was studied by monitoring the dynamic balance between intracellular ATP release and ectoATPase activity. Following mechanical and hypotonic stimuli, Caco-2 cells triggered a strong but transient release of intracellular ATP, with almost no energy cost, leading to a steep increase of eATP concentration, which was later reduced by ectoATPase activity. A data-driven algorithm allowed quantifying and predicting the rates of ATP release and ATP consumption contributing to the dynamic accumulation of ATP at the cell surface.
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Affiliation(s)
- J Schachter
- Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini", Universidad de Buenos Aires (UBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica, Junín 956, C1113AAD Buenos Aires, Argentina.
| | - C L Alvarez
- Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini", Universidad de Buenos Aires (UBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica, Junín 956, C1113AAD Buenos Aires, Argentina; Universidad de Buenos Aires (UBA), Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica, Junín 956, C1113AAD Buenos Aires, Argentina
| | - Z Bazzi
- Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini", Universidad de Buenos Aires (UBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica, Junín 956, C1113AAD Buenos Aires, Argentina
| | - M P Faillace
- Instituto de Fisiología y Biofísica Prof. Bernardo Houssay (IFIBIO-Houssay), Universidad de Buenos Aires (UBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina; Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - G Corradi
- Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini", Universidad de Buenos Aires (UBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica, Junín 956, C1113AAD Buenos Aires, Argentina; Universidad de Buenos Aires (UBA), Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica, Junín 956, C1113AAD Buenos Aires, Argentina
| | - C Hattab
- Université de Paris, UMR_S1134, BIGR, Inserm, F-75015 Paris, France; Institut National de la Transfusion Sanguine, Laboratoire d'Excellence GR-Ex, F-75015 Paris, France
| | - D E Rinaldi
- Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini", Universidad de Buenos Aires (UBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica, Junín 956, C1113AAD Buenos Aires, Argentina; Universidad de Buenos Aires (UBA), Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica, Junín 956, C1113AAD Buenos Aires, Argentina
| | - R Gonzalez-Lebrero
- Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini", Universidad de Buenos Aires (UBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica, Junín 956, C1113AAD Buenos Aires, Argentina; Universidad de Buenos Aires (UBA), Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica, Junín 956, C1113AAD Buenos Aires, Argentina
| | - M Pucci Molineris
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP) "Prof. Dr. Rodolfo R. Brenner", Universidad Nacional de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Médicas, Av. 60 y Av. 120, La Plata, Argentina; Universidad Nacional de La Plata, Facultad de Ciencias Médicas, Av. 60 y Av. 120, La Plata, Argentina
| | - J Sévigny
- Centre de Recherche du CHU de Québec-Université Laval, Québec, QC, Canada; Département de Microbiologie-Infectiologie et d'Immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - M A Ostuni
- Université de Paris, UMR_S1134, BIGR, Inserm, F-75015 Paris, France; Institut National de la Transfusion Sanguine, Laboratoire d'Excellence GR-Ex, F-75015 Paris, France
| | - P J Schwarzbaum
- Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini", Universidad de Buenos Aires (UBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica, Junín 956, C1113AAD Buenos Aires, Argentina; Universidad de Buenos Aires (UBA), Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica, Junín 956, C1113AAD Buenos Aires, Argentina.
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Fajrial AK, Liu K, Gao Y, Gu J, Lakerveld R, Ding X. Characterization of Single-Cell Osmotic Swelling Dynamics for New Physical Biomarkers. Anal Chem 2021; 93:1317-1325. [PMID: 33253534 DOI: 10.1021/acs.analchem.0c02289] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Characterization of cell physical biomarkers is vital to understand cell properties and applicable for disease diagnostics. Current methods used to analyze physical phenotypes involve external forces to deform the cells. Alternatively, internal tension forces via osmotic swelling can also deform the cells. However, an established assumption contends that the forces generated during hypotonic swelling concentrated on the plasma membrane are incapable of assessing the physical properties of nucleated cells. Here, we utilized an osmotic swelling approach to characterize different types of nucleated cells. Using a microfluidic device for cell trapping arrays with truncated hanging micropillars (CellHangars), we isolated single cells and evaluated the swelling dynamics during the hypotonic challenge at 1 s time resolution. We demonstrated that cells with different mechanical phenotypes showed unique swelling dynamics signature. Different types of cells can be classified with an accuracy of up to ∼99%. We also showed that swelling dynamics can detect cellular mechanical property changes due to cytoskeleton disruption. Considering its simplicity, swelling dynamics offers an invaluable label-free physical biomarker for cells with potential applications in both biological studies and clinical practice.
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Affiliation(s)
- Apresio K Fajrial
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States
| | - Kun Liu
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States
| | - Yu Gao
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States
| | - Junhao Gu
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Richard Lakerveld
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xiaoyun Ding
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States.,Biomedical Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
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Wei ZY, Qu HL, Dai YJ, Wang Q, Ling ZM, Su WF, Zhao YY, Shen WX, Chen G. Pannexin 1, a large-pore membrane channel, contributes to hypotonicity-induced ATP release in Schwann cells. Neural Regen Res 2021; 16:899-904. [PMID: 33229726 PMCID: PMC8178772 DOI: 10.4103/1673-5374.290911] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pannexin 1 (Panx 1), as a large-pore membrane channel, is highly permeable to ATP and other signaling molecules. Previous studies have demonstrated the expression of Panx 1 in the nervous system, including astrocytes, microglia, and neurons. However, the distribution and function of Panx 1 in the peripheral nervous system are not clear. Blocking the function of Panx 1 pharmacologically (carbenoxolone and probenecid) or with small interfering RNA targeting pannexins can greatly reduce hypotonicity-induced ATP release. Treatment of Schwann cells with a Ras homolog family member (Rho) GTPase inhibitor and small interfering RNA targeting Rho or cytoskeleton disrupting agents, such as nocodazole or cytochalasin D, revealed that hypotonicity-induced ATP release depended on intracellular RhoA and the cytoskeleton. These findings suggest that Panx 1 participates in ATP release in Schwann cells by regulating RhoA and the cytoskeleton arrangement. This study was approved by the Animal Ethics Committee of Nantong University, China (No. S20180806-002) on August 5, 2018.
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Affiliation(s)
- Zhong-Ya Wei
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Hui-Lin Qu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Yu-Juan Dai
- Medical School of Nantong University, Nantong, Jiangsu Province, China
| | - Qian Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Zhuo-Min Ling
- Medical School of Nantong University, Nantong, Jiangsu Province, China
| | - Wen-Feng Su
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Ya-Yu Zhao
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Wei-Xing Shen
- Medical School of Nantong University, Nantong, Jiangsu Province, China
| | - Gang Chen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University; Medical School of Nantong University; Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, China
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Extracellular ATP: A Feasible Target for Cancer Therapy. Cells 2020; 9:cells9112496. [PMID: 33212982 PMCID: PMC7698494 DOI: 10.3390/cells9112496] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 12/22/2022] Open
Abstract
Adenosine triphosphate (ATP) is one of the main biochemical components of the tumor microenvironment (TME), where it can promote tumor progression or tumor suppression depending on its concentration and on the specific ecto-nucleotidases and receptors expressed by immune and cancer cells. ATP can be released from cells via both specific and nonspecific pathways. A non-regulated release occurs from dying and damaged cells, whereas active release involves exocytotic granules, plasma membrane-derived microvesicles, specific ATP-binding cassette (ABC) transporters and membrane channels (connexin hemichannels, pannexin 1 (PANX1), calcium homeostasis modulator 1 (CALHM1), volume-regulated anion channels (VRACs) and maxi-anion channels (MACs)). Extracellular ATP acts at P2 purinergic receptors, among which P2X7R is a key mediator of the final ATP-dependent biological effects. Over the years, P2 receptor- or ecto-nucleotidase-targeting for cancer therapy has been proposed and actively investigated, while comparatively fewer studies have explored the suitability of TME ATP as a target. In this review, we briefly summarize the available evidence suggesting that TME ATP has a central role in determining tumor fate and is, therefore, a suitable target for cancer therapy.
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Kim J, Cheong JH. Role of Mitochondria-Cytoskeleton Interactions in the Regulation of Mitochondrial Structure and Function in Cancer Stem Cells. Cells 2020; 9:cells9071691. [PMID: 32674438 PMCID: PMC7407978 DOI: 10.3390/cells9071691] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/09/2020] [Accepted: 07/11/2020] [Indexed: 12/16/2022] Open
Abstract
Despite the promise of cancer medicine, major challenges currently confronting the treatment of cancer patients include chemoresistance and recurrence. The existence of subpopulations of cancer cells, known as cancer stem cells (CSCs), contributes to the failure of cancer therapies and is associated with poor clinical outcomes. Of note, one of the recently characterized features of CSCs is augmented mitochondrial function. The cytoskeleton network is essential in regulating mitochondrial morphology and rearrangement, which are inextricably linked to its functions, such as oxidative phosphorylation (OXPHOS). The interaction between the cytoskeleton and mitochondria can enable CSCs to adapt to challenging conditions, such as a lack of energy sources, and to maintain their stemness. Cytoskeleton-mediated mitochondrial trafficking and relocating to the high energy requirement region are crucial steps in epithelial-to-mesenchymal transition (EMT). In addition, the cytoskeleton itself interplays with and blocks the voltage-dependent anion channel (VDAC) to directly regulate bioenergetics. In this review, we describe the regulation of cellular bioenergetics in CSCs, focusing on the cytoskeleton-mediated dynamic control of mitochondrial structure and function.
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Affiliation(s)
- Jungmin Kim
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Korea;
| | - Jae-Ho Cheong
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Korea;
- Department of Surgery, Yonsei University Health System, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea
- Yonsei Biomedical Research Institute, Yonsei University College of Medicine, Seoul 03722, Korea
- Department of Biochemistry & Molecular Biology, Yonsei University College of Medicine, Seoul 03722, Korea
- Department of Biomedical Systems Informatics, Yonsei University College of Medicine, Seoul 03722, Korea
- Correspondence: ; Tel.: +82-2-2228-2094; Fax: +82-2-313-8289
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Detection of Osmotic Shock-Induced Extracellular Nucleotide Release with a Genetically Encoded Fluorescent Sensor of ADP and ATP. SENSORS 2019; 19:s19153253. [PMID: 31344821 PMCID: PMC6695626 DOI: 10.3390/s19153253] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 07/17/2019] [Accepted: 07/19/2019] [Indexed: 01/19/2023]
Abstract
Purinergic signals, such as extracellular adenosine triphosphate (ATP) and adenosine diphosphate (ADP), mediate intercellular communication and stress responses throughout mammalian tissues, but the dynamics of their release and clearance are still not well understood. Although physiochemical methods provide important insight into physiology, genetically encoded optical sensors have proven particularly powerful in the quantification of signaling in live specimens. Indeed, genetically encoded luminescent and fluorescent sensors provide new insights into ATP-mediated purinergic signaling. However, new tools to detect extracellular ADP are still required. To this end, in this study, we use protein engineering to generate a new genetically encoded sensor that employs a high-affinity bacterial ADP-binding protein and reports a change in occupancy with a change in the Förster-type resonance energy transfer (FRET) between cyan and yellow fluorescent proteins. We characterize the sensor in both protein solution studies, as well as live-cell microscopy. This new sensor responds to nanomolar and micromolar concentrations of ADP and ATP in solution, respectively, and in principle it is the first fully-genetically encoded sensor with sufficiently high affinity for ADP to detect low levels of extracellular ADP. Furthermore, we demonstrate that tethering the sensor to the cell surface enables the detection of physiologically relevant nucleotide release induced by hypoosmotic shock as a model of tissue edema. Thus, we provide a new tool to study purinergic signaling that can be used across genetically tractable model systems.
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Synergic stress in striped catfish (Pangasianodon hypophthalmus, S.) exposed to chronic salinity and bacterial infection: Effects on kidney protein expression profile. J Proteomics 2016; 142:91-101. [DOI: 10.1016/j.jprot.2016.04.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/28/2016] [Accepted: 04/28/2016] [Indexed: 12/14/2022]
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Shukla PK, Gangwar R, Manda B, Meena AS, Yadav N, Szabo E, Balogh A, Lee SC, Tigyi G, Rao R. Rapid disruption of intestinal epithelial tight junction and barrier dysfunction by ionizing radiation in mouse colon in vivo: protection by N-acetyl-l-cysteine. Am J Physiol Gastrointest Liver Physiol 2016; 310:G705-15. [PMID: 26822914 PMCID: PMC4867328 DOI: 10.1152/ajpgi.00314.2015] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 01/12/2016] [Indexed: 01/31/2023]
Abstract
The goals of this study were to evaluate the effects of ionizing radiation on apical junctions in colonic epithelium and mucosal barrier function in mice in vivo. Adult mice were subjected to total body irradiation (4 Gy) with or without N-acetyl-l-cysteine (NAC) feeding for 5 days before irradiation. At 2-24 h postirradiation, the integrity of colonic epithelial tight junctions (TJ), adherens junctions (AJ), and the actin cytoskeleton was assessed by immunofluorescence microscopy and immunoblot analysis of detergent-insoluble fractions for TJ and AJ proteins. The barrier function was evaluated by measuring vascular-to-luminal flux of fluorescein isothiocyanate (FITC)-inulin in vivo and luminal-to-mucosal flux in vitro. Oxidative stress was evaluated by measuring protein thiol oxidation. Confocal microscopy showed that radiation caused redistribution of occludin, zona occludens-1, claudin-3, E-cadherin, and β-catenin, as well as the actin cytoskeleton as early as 2 h postirradiation, and this effect was sustained for at least 24 h. Feeding NAC before irradiation blocked radiation-induced disruption of TJ, AJ, and the actin cytoskeleton. Radiation increased mucosal permeability to inulin in colon, which was blocked by NAC feeding. The level of reduced-protein thiols in colon was depleted by radiation with a concomitant increase in the level of oxidized-protein thiol. NAC feeding blocked the radiation-induced protein thiol oxidation. These data demonstrate that radiation rapidly disrupts TJ, AJ, and the actin cytoskeleton by an oxidative stress-dependent mechanism that can be prevented by NAC feeding.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - RadhaKrishna Rao
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
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Hypoxia is an effective stimulus for vesicular release of ATP from human umbilical vein endothelial cells. Placenta 2015; 36:759-66. [PMID: 25956988 PMCID: PMC4502406 DOI: 10.1016/j.placenta.2015.04.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/26/2015] [Accepted: 04/09/2015] [Indexed: 12/12/2022]
Abstract
Introduction Hypoxia induces dilatation of the umbilical vein by releasing autocoids from endothelium; prostaglandins (PGs), adenosine and nitric oxide (NO) have been implicated. ATP is vasoactive, thus we tested whether hypoxia releases ATP from primary Human Umbilical Vein Endothelial Cells (HUVEC). Methods HUVEC were grown on inserts under no-flow conditions. ATP was assayed by luciferin–luciferase and visualised by quinacrine labeling. Intracellular Ca2+ ([Ca2+]i) was imaged with Fura-2. Results ATP release occurred constitutively and was increased by hypoxia (PO2: 150–8 mmHg), ∼10-fold more from apical, than basolateral surface. Constitutive ATP release was decreased, while hypoxia-induced release was abolished by brefeldin or monensin A, inhibitors of vesicular transport, and LY294002 or Y27632, inhibitors of phosphoinositide 3-kinases (PI3K) and Rho-associated protein kinase (ROCK). ATP release was unaffected by NO donor, but increased by calcium ionophore, by >60-fold from apical, but <25% from basolateral surface. Hypoxia induced a small increase in [Ca2+]i compared with ATP (10 μM); hypoxia inhibited the ATP response. Quinacrine-ATP fluorescent loci in the perinuclear space, were diminished by hypoxia and monensin, whereas brefeldin A increased fluorescence intensity, consistent with inhibition of anterograde transport. Discussion. Hypoxia within the physiological range releases ATP from HUVEC, particularly from apical/adluminal surfaces by exocytosis, via an increase in [Ca2+]i, PI3K and ROCK, independently of NO. We propose that hypoxia releases ATP at concentrations sufficient to induce umbilical vein dilation via PGs and NO and improve fetal blood flow, but curbs amplification of ATP release by autocrine actions of ATP, so limiting its pro-inflammatory effects. Hypoxia releases ATP from Human umbilical vein endothelial cells (HUVEC). This ATP release is preferentially from apical surfaces. Polarised ATP release is also triggered by Ca2+ ionophore. Hypoxia-induced ATP release occurs from vesicles, as visualised by quinacrine. It is attenuated by inhibitors of vesicular trafficking, PI3K and ROCK.
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Zhan R, Yang S, He W, Wang F, Tan J, Zhou J, Yang S, Yao Z, Wu J, Luo G. Nitric oxide enhances keratinocyte cell migration by regulating Rho GTPase via cGMP-PKG signalling. PLoS One 2015; 10:e0121551. [PMID: 25799230 PMCID: PMC4370851 DOI: 10.1371/journal.pone.0121551] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 02/02/2015] [Indexed: 01/12/2023] Open
Abstract
Objective Nitric oxide (NO) has been shown to improve wound healing, but the mechanism underlying this function is not well defined. Here, we explored the effect of NO on the migration of a human keratinocyte cell line (HaCaT) and its possible mechanism. Methods The effects of NO on HaCaT cells in the presence of different concentrations of the NO donor sodium nitroprusside (SNP) were evaluated in a cell migration assay. Subsequently, the cytoskeleton reorganization of cultured HaCaT cells stained with rhodamine-phalloidin was observed with a confocal laser scanning microscope. The mRNA expression and active proteins of CDC42, Rac1 and RhoA in the cultured cells were determined via RT-PCR and pull-down assays, respectively. Furthermore, the roles of various inhibitors or agonists specific to cGMP, PKG and CDC42, Rac1, RhoA in the effects of NO on HaCaT cell migration, F-actin stress fibre formation, and Rho GTPase expression were observed. Results It was also found HaCaT cell migration was increased by SNP in a dose-dependent manner, and the other two NO donors either spermine NONOate or SNAP had almost the same effects on HaCat cell migrations. The formation of F-actin stress fibres in SNP-treated HaCaT cells was increased. The mRNA expression and the active proteins of CDC42, Rac1 and RhoA were found to be upregulated after SNP treatment. Similar effects were observed after the cells were treated with a cGMP or PKG agonist. Additionally, the SNP-mediated upregulation of the mRNA expression and the active proteins of CDC42, Rac1 and RhoA were inhibited by the addition of an inhibitor of cGMP or PKG. Moreover, the SNP-mediated promoting effects of migration and cytoskeleton reorganization were inhibited by treatment with inhibitors of cGMP, PKG, CDC42, Rac1 and RhoA respectively. Conclusion Our data indicated that the stimulatory effects of NO on cell migration of HaCaT cells are mediated by the cGMP signalling pathway via the upregulation of Rho-GTPase expression, which might promote cytoskeleton reorganization.
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Affiliation(s)
- Rixing Zhan
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Shiwei Yang
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Weifeng He
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Fan Wang
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Jianglin Tan
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Junyi Zhou
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Sisi Yang
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Zhihui Yao
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Jun Wu
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
- * E-mail: (JW); (GL)
| | - Gaoxing Luo
- Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Key Laboratory of Disease Proteomics of Chongqing, Southwest Hospital, Third Military Medical University, Chongqing, China
- * E-mail: (JW); (GL)
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12
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Son GY, Yang YM, Park WS, Chang I, Shin DM. Hypotonic stress induces RANKL via transient receptor potential melastatin 3 (TRPM3) and vaniloid 4 (TRPV4) in human PDL cells. J Dent Res 2015; 94:473-81. [PMID: 25595364 DOI: 10.1177/0022034514567196] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Bone remodeling occurs in response to various types of mechanical stress. The periodontal ligament (PDL) plays an important role in mechanical stress-mediated alveolar bone remodeling. However, the underlying mechanism at the cellular level has not been extensively studied. In this study, we investigated the effect of shear stress on the expression of bone remodeling factors, including receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL) and osteoprotegerin (OPG), as well as its upstream signaling pathway in primary human PDL cells. We applied hypotonic stress to reproduce shear stress to PDL cells. Hypotonic stress induced the messenger RNA (mRNA) and protein expression of RANKL but not OPG. It also increased intracellular Ca(2+) concentration ([Ca(2+)]i). Extracellular Ca(2+) depletion and nonspecific plasma membrane Ca(2+) channel blockers completely inhibited the increase in both [Ca(2+)]i and RANKL mRNA expression. We identified the expression and activation of transient receptor potential melastatin 3 (TRPM3) and vaniloid 4 (TRPV4) channels in PDL cells. Pregnenolone sulfate (PS) and 4α-phorbol 12, 13-didecanoate (4α-PDD), which are agonists of TRPM3 and TRPV4, augmented Ca(2+) influx and RANKL mRNA expression. Both pharmacological (2-aminoethoxydiphenyl borate [2-APB], ruthenium red [RR], ononetin [Ono], and HC 067047 [HC]) and genetic (small interfering RNA [siRNA]) inhibitors of TRPM3 and TRPV4 reduced the hypotonic stress-mediated increase in [Ca(2+)]i and RANKL mRNA expression. Our study shows that hypotonic stress induced RANKL mRNA expression via TRPM3- and TRPV4-mediated extracellular Ca(2+) influx and RANKL expression. This signaling pathway in PDL cells may play a critical role in mechanical stress-mediated alveolar bone remodeling.
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Affiliation(s)
- G Y Son
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Korea BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Korea
| | - Y M Yang
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Korea
| | - W S Park
- Department of Advanced General Dentistry, Yonsei University College of Dentistry, Seoul, Korea
| | - I Chang
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Korea
| | - D M Shin
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Korea BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Korea
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13
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Exaggerated increases in blood pressure during isometric muscle contraction in hypertension: role for purinergic receptors. Auton Neurosci 2014; 188:51-7. [PMID: 25577671 DOI: 10.1016/j.autneu.2014.12.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 10/15/2014] [Accepted: 12/17/2014] [Indexed: 01/27/2023]
Abstract
Physical activity is a cornerstone therapy for the primary prevention and treatment of hypertension, which is becoming increasingly prevalent in modern societies. During exercise, heart rate and blood pressure (BP) increase in order to acutely meet the metabolic demands of the working skeletal muscle. In hypertensive adults, isometric exercise-induced increases in BP are excessive, potentially increasing the risk of an acute cardiovascular event during or after physical activity. Recently, the skeletal muscle metaboreflex has emerged as a significant contributor to the development of aberrant cardiovascular control during isometric exercise in this clinical population. Our laboratory has conducted a series of studies characterizing the skeletal muscle metaboreflex in hypertensive humans. We and others have demonstrated that hypertension is characterized by greater increases in muscle sympathetic nerve activity and BP during selective activation of the metaboreflex during post-exercise muscle ischemia compared to the increases noted in healthy age-matched normotensive adults, suggesting that the skeletal muscle metaboreflex is exaggerated in human hypertension. The focus of this review is the skeletal muscle metaboreflex (i.e., the metabolic component of the exercise pressor reflex) in hypertension, with particular emphasis on the potential role of purinergic receptors in mediating the exaggerated responses to muscle metaboreflex activation.
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14
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Ohbuchi T, Takenaga F, Hohchi N, Wakasugi T, Ueta Y, Suzuki H. Possible contribution of pannexin-1 to ATP release in human upper airway epithelia. PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS 2014; 2:e00227. [PMID: 24744896 PMCID: PMC3966237 DOI: 10.1002/phy2.227] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 01/07/2023]
Abstract
Pannexins are a family of transmembrane nonselective channel proteins that participate in the release of ATP into extracellular space. Previous studies have suggested that pannexin-1 (Panx1) may constitute a local autocrine/paracrine system via transmitter ATP in association with the purinergic P2X7 receptor. In this study, we investigate the expressions of Panx1 and P2X7 in human nasal mucosa, together with hypotonic stress-induced ATP release from this tissue. Twenty men and one woman ranging in age from 10 to 82 years with an average age of 44.2 ± 4.4 years participated in the study. Inferior turbinates were collected from patients with chronic hypertrophic rhinitis during endoscopic endonasal surgery. The expressions of Panx1 and P2X7 were examined by fluorescence immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). We also examined hypotonic stress-induced ATP release from the turbinate mucosa and the effects of channel blockers in an ex vivo experiment. Substantial expressions of both proteins were observed in human nasal mucosa. The immunoreactivity for Panx1 was stronger than that for P2X7. The presence of the transcripts of Panx1 and P2X7 was also shown by qRT-PCR. Ten and 100 μmol/L carbenoxolone (a Panx1 channel blocker) significantly inhibited the ATP release from the nasal mucosa, but flufenamic acid (a connexin channel blocker) and gadolinium (a stretch-activated channel blocker) did not. These results indicate the coexistence of Panx1 and P2X7 in, and Panx1-dependent ATP release from, the human nasal mucosa, suggesting the possible participation of these molecules in the physiological functions of the upper airway.
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Affiliation(s)
- Toyoaki Ohbuchi
- Department of Otorhinolaryngology‐Head and Neck Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Fumiko Takenaga
- Department of Otorhinolaryngology‐Head and Neck Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Nobusuke Hohchi
- Department of Otorhinolaryngology‐Head and Neck Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Tetsuro Wakasugi
- Department of Otorhinolaryngology‐Head and Neck Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Yoichi Ueta
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Hideaki Suzuki
- Department of Otorhinolaryngology‐Head and Neck Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
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15
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Langevin HM, Nedergaard M, Howe AK. Cellular control of connective tissue matrix tension. J Cell Biochem 2013; 114:1714-9. [PMID: 23444198 DOI: 10.1002/jcb.24521] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 02/12/2013] [Indexed: 12/21/2022]
Abstract
The biomechanical behavior of connective tissue in response to stretching is generally attributed to the molecular composition and organization of its extracellular matrix. It also is becoming apparent that fibroblasts play an active role in regulating connective tissue tension. In response to static stretching of the tissue, fibroblasts expand within minutes by actively remodeling their cytoskeleton. This dynamic change in fibroblast shape contributes to the drop in tissue tension that occurs during viscoelastic relaxation. We propose that this response of fibroblasts plays a role in regulating extracellular fluid flow into the tissue, and protects against swelling when the matrix is stretched. This article reviews the evidence supporting possible mechanisms underlying this response including autocrine purinergic signaling. We also discuss fibroblast regulation of connective tissue tension with respect to lymphatic flow, immune function, and cancer.
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Affiliation(s)
- Helene M Langevin
- Department of Neurological Sciences, Vermont Cancer Center, University of Vermont, Burlington, Vermont, USA.
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16
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Langevin HM, Fujita T, Bouffard NA, Takano T, Koptiuch C, Badger GJ, Nedergaard M. Fibroblast cytoskeletal remodeling induced by tissue stretch involves ATP signaling. J Cell Physiol 2013; 228:1922-6. [PMID: 23460361 DOI: 10.1002/jcp.24356] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 02/12/2013] [Indexed: 12/16/2022]
Abstract
Fibroblasts in whole areolar connective tissue respond to static stretching of the tissue by expanding and remodeling their cytoskeleton within minutes both ex vivo and in vivo. This study tested the hypothesis that the mechanism of fibroblast expansion in response to tissue stretch involves extracellular ATP signaling. In response to tissue stretch ex vivo, ATP levels in the bath solution increased significantly, and this increase was sustained for 20 min, returning to baseline at 60 min. No increase in ATP was observed in tissue incubated without stretch or tissue stretched in the presence of the Rho kinase inhibitor Y27632. The increase in fibroblast cross sectional area in response to tissue stretch was blocked by both suramin (a purinergic receptor blocker) and apyrase (an enzyme that selectively degrades extracellular ATP). Furthermore, connexin channel blockers (octanol and carbenoxolone), but not VRAC (fluoxetine) or pannexin (probenecid) channel blockers, inhibited fibroblast expansion. Together, these results support a mechanism in which extracellular ATP signaling via connexin hemichannels mediate the active change in fibroblast shape that occurs in response to a static increase in tissue length.
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Affiliation(s)
- Helene M Langevin
- Department of Neurological Sciences, University of Vermont, Burlington, Vermont 05405, USA.
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17
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Roudaut Y, Lonigro A, Coste B, Hao J, Delmas P, Crest M. Touch sense: functional organization and molecular determinants of mechanosensitive receptors. Channels (Austin) 2013; 6:234-45. [PMID: 23146937 DOI: 10.4161/chan.22213] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cutaneous mechanoreceptors are localized in the various layers of the skin where they detect a wide range of mechanical stimuli, including light brush, stretch, vibration and noxious pressure. This variety of stimuli is matched by a diverse array of specialized mechanoreceptors that respond to cutaneous deformation in a specific way and relay these stimuli to higher brain structures. Studies across mechanoreceptors and genetically tractable sensory nerve endings are beginning to uncover touch sensation mechanisms. Work in this field has provided researchers with a more thorough understanding of the circuit organization underlying the perception of touch. Novel ion channels have emerged as candidates for transduction molecules and properties of mechanically gated currents improved our understanding of the mechanisms of adaptation to tactile stimuli. This review highlights the progress made in characterizing functional properties of mechanoreceptors in hairy and glabrous skin and ion channels that detect mechanical inputs and shape mechanoreceptor adaptation.
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Affiliation(s)
- Yann Roudaut
- Aix-Marseille Université, CNRS, Marseille, France
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18
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Espelt MV, de Tezanos Pinto F, Alvarez CL, Alberti GS, Incicco J, Leal Denis MF, Davio C, Schwarzbaum PJ. On the role of ATP release, ectoATPase activity, and extracellular ADP in the regulatory volume decrease of Huh-7 human hepatoma cells. Am J Physiol Cell Physiol 2013; 304:C1013-26. [PMID: 23485713 DOI: 10.1152/ajpcell.00254.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypotonicity triggered in human hepatoma cells (Huh-7) the release of ATP and cell swelling, followed by volume regulatory decrease (RVD). We analyzed how the interaction between those processes modulates cell volume. Cells exposed to hypotonic medium swelled 1.5 times their basal volume. Swelling was followed by 41% RVD(40) (extent of RVD after 40 min of maximum), whereas the concentration of extracellular ATP (ATP(e)) increased 10 times to a maximum value at 15 min. Exogenous apyrase (which removes di- and trinucleotides) did not alter RVD, whereas exogenous Na(+)-K(+)-ATPase (which converts ATP to ADP in the extracellular medium) enhanced RVD(40) by 2.6 times, suggesting that hypotonic treatment alone produced a basal RVD, whereas extracellular ADP activated RVD to achieve complete volume regulation (i.e., RVD(40) ≈100%). Under hypotonicity, addition of 2-(methylthio)adenosine 5'-diphosphate (2MetSADP; ADP analog) increased RVD to the same extent as exposure to Na(+)-K(+)-ATPase and the same analog did not stimulate RVD when coincubated with MRS2211, a blocker of ADP receptor P2Y(13). RT-PCR and Western blot analysis confirmed the presence of P2Y(13). Cells exhibited significant ectoATPase activity, which according to RT-PCR analysis can be assigned to ENTPDase2. Both carbenoxolone, a blocker of conductive ATP release, and brefeldin A, an inhibitor of exocytosis, were able to partially decrease ATP(e) accumulation, pointing to the presence of at least two mechanisms for ATP release. Thus, in Huh-7 cells, hypotonic treatment triggered the release of ATP. Conversion of ATP(e) to ADP(e) by ENTPDase 2 activity facilitates the accumulated ADP(e) to activate P2Y(13) receptors, which mediate complete RVD.
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Affiliation(s)
- María V Espelt
- Instituto de Química y Fisicoquímica Biológicas (Facultad de Farmacia y Bioquímica), Universidad de Buenos Aires, Buenos Aires, Argentina.
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19
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Ohshima Y, Tsukimoto M, Harada H, Kojima S. Involvement of connexin43 hemichannel in ATP release after γ-irradiation. JOURNAL OF RADIATION RESEARCH 2012; 53:551-7. [PMID: 22843620 PMCID: PMC3393350 DOI: 10.1093/jrr/rrs014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Ionizing radiation induces biological effects not only in irradiated cells but also in non-irradiated cells, which is called the bystander effect. Recently, in vivo and in vitro experiments have suggested that both gap junction hemichannel connexin43 (Cx43) and extracellular adenosine triphosphate (ATP) released from cells play a role in the bystander effect. We have reported that γ-irradiation induces ATP release from B16 melanoma cells, which is dependent on the P2X(7) receptor. However, the mechanism of ATP release caused by irradiation remains unclear. We here show the involvement of Cx43 in P2X(7) receptor-dependent ATP release after 0.5 Gy γ-irradiation. Inhibitors of gap junction hemichannels and an inhibitory peptide for Cx43 (gap26), but not an inhibitory peptide for pannexin1 (Panx1), significantly blocked γ-irradiation-induced ATP release from B16 melanoma cells. We confirmed high expression of Cx43 mRNA in B16 melanoma cells. These results suggest involvement of Cx43 in radiation-induced ATP release. We found that after 0.5 Gy γ-irradiation tyrosine phosphorylation was significantly blocked by P2X(7) receptor antagonist, but not gap26, suggesting that tyrosine phosphorylation is a downstream event from the P2X(7) receptor. Since tyrosine kinase inhibitor significantly suppressed radiation-induced ATP release, tyrosine phosphorylation appears to play an important role in the Cx43-mediated ATP release downstream of the P2X(7) receptor. In conclusion, the Cx43 hemichannel, which lies downstream of the P2X(7) receptor, is involved in ATP release in response to radiation. Our results suggest a novel mechanism for radiation-induced biological effects mediated by both ATP and Cx43.
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Affiliation(s)
- Yasuhiro Ohshima
- Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-0022, Japan
- Medical Radioisotope Application Group, Medical and Biotechnological Application Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki-shi, Gunma 370-1292, Japan
| | - Mitsutoshi Tsukimoto
- Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-0022, Japan
- Corresponding author. Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-0022, Japan; Tel: +81 (0) 4 7124 1501 (ext. 6443); Fax: +81 (0) 4 7121 3613;
| | - Hitoshi Harada
- Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, 3500-3 Minamitamagaki-cho, Suzuka-shi, Mie 513-8670, Japan
| | - Shuji Kojima
- Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-0022, Japan
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20
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Sandow SL, Senadheera S, Grayson TH, Welsh DG, Murphy TV. Calcium and endothelium-mediated vasodilator signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:811-31. [PMID: 22453971 DOI: 10.1007/978-94-007-2888-2_36] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Vascular tone refers to the balance between arterial constrictor and dilator activity. The mechanisms that underlie tone are critical for the control of haemodynamics and matching circulatory needs with metabolism, and thus alterations in tone are a primary factor for vascular disease etiology. The dynamic spatiotemporal control of intracellular Ca(2+) levels in arterial endothelial and smooth muscle cells facilitates the modulation of multiple vascular signaling pathways. Thus, control of Ca(2+) levels in these cells is integral for the maintenance of tone and blood flow, and intimately associated with both physiological and pathophysiological states. Hence, understanding the mechanisms that underlie the modulation of vascular Ca(2+) activity is critical for both fundamental knowledge of artery function, and for the development of targeted therapies. This brief review highlights the role of Ca(2+) signaling in vascular endothelial function, with a focus on contact-mediated vasodilator mechanisms associated with endothelium-derived hyperpolarization and the longitudinal conduction of responses over distance.
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Affiliation(s)
- Shaun L Sandow
- Department of Physiology, School of Medical Sciences, University of New South Wales, 2052 Sydney, NSW, Australia.
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21
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Seminario-Vidal L, Okada SF, Sesma JI, Kreda SM, van Heusden CA, Zhu Y, Jones LC, O'Neal WK, Penuela S, Laird DW, Boucher RC, Lazarowski ER. Rho signaling regulates pannexin 1-mediated ATP release from airway epithelia. J Biol Chem 2011; 286:26277-86. [PMID: 21606493 DOI: 10.1074/jbc.m111.260562] [Citation(s) in RCA: 171] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ATP released from airway epithelial cells promotes purinergic receptor-regulated mucociliary clearance activities necessary for innate lung defense. Cell swelling-induced membrane stretch/strain is a common stimulus that promotes airway epithelial ATP release, but the mechanisms transducing cell swelling into ATP release are incompletely understood. Using knockdown and knockout approaches, we tested the hypothesis that pannexin 1 mediates ATP release from hypotonically swollen airway epithelia and investigated mechanisms regulating this activity. Well differentiated primary cultures of human bronchial epithelial cells subjected to hypotonic challenge exhibited enhanced ATP release, which was paralleled by the uptake of the pannexin probe propidium iodide. Both responses were reduced by pannexin 1 inhibitors and by knocking down pannexin 1. Importantly, hypotonicity-evoked ATP release from freshly excised tracheas and dye uptake in primary tracheal epithelial cells were impaired in pannexin 1 knockout mice. Hypotonicity-promoted ATP release and dye uptake in primary well differentiated human bronchial epithelial cells was accompanied by RhoA activation and myosin light chain phosphorylation and was reduced by the RhoA dominant negative mutant RhoA(T19N) and Rho and myosin light chain kinase inhibitors. ATP release and Rho activation were reduced by highly selective inhibitors of transient receptor potential vanilloid 4 (TRPV4). Lastly, knocking down TRPV4 impaired hypotonicity-evoked airway epithelial ATP release. Our data suggest that TRPV4 and Rho transduce cell membrane stretch/strain into pannexin 1-mediated ATP release in airway epithelia.
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Affiliation(s)
- Lucia Seminario-Vidal
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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22
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Gendaszewska-Darmach E, Kucharska M. Nucleotide receptors as targets in the pharmacological enhancement of dermal wound healing. Purinergic Signal 2011; 7:193-206. [PMID: 21519856 PMCID: PMC3146642 DOI: 10.1007/s11302-011-9233-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 04/10/2011] [Indexed: 12/15/2022] Open
Abstract
With a growing interest of the involvement of extracellular nucleotides in both normal physiology and pathology, it has become evident that P2 receptor agonists and antagonists may have therapeutic potential. The P2Y2 receptor agonists (diquafosol tetrasodium and denufosol tetrasodium) are in the phase 3 of clinical trials for dry eye and cystic fibrosis, respectively. The thienopyridine derivatives clopidogrel and ticlopidine (antagonists of the platelet P2Y12 receptor) have been used in cardiovascular medicine for nearly a decade. Purines and pyrimidines may be of therapeutic potential also in wound healing since ATP and UTP have been shown to have many hallmarks of wound healing factors. Recent studies have demonstrated that extracellular nucleotides take part in all phases of wound repair: hemostasis, inflammation, tissue formation, and tissue remodeling. This review is focused on the potent purines and pyrimidines which regulate many physiological processes important for wound healing.
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Affiliation(s)
- Edyta Gendaszewska-Darmach
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Technical University of Lodz, Stefanowskiego 4/10, 90-924, Lodz, Poland,
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23
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Praetorius HA, Leipziger J. Intrarenal purinergic signaling in the control of renal tubular transport. Annu Rev Physiol 2010; 72:377-93. [PMID: 20148681 DOI: 10.1146/annurev-physiol-021909-135825] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Renal tubular epithelial cells receive hormonal input that regulates volume and electrolyte homeostasis. In addition, numerous intrarenal, local signaling agonists have appeared on the stage of renal physiology. One such system is that of intrarenal purinergic signaling. This system involves all the elements necessary for agonist-mediated intercellular communication. ATP is released from epithelial cells, which activates P2 receptors in the apical and basolateral membrane and thereby modulates tubular transport. Termination of the signal is conducted via the breakdown of ATP to adenosine. Recent far-reaching advances indicate that ATP is often used as a local transmitter for classical sensory transduction. This transmission apparently also applies to sensory functions in the kidney. Locally released ATP is involved in sensing of renal tubular flow or in detecting the distal tubular load of NaCl at the macula densa. This review describes the relevant aspects of local, intrarenal purinergic signaling and outlines its integrative concepts.
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Affiliation(s)
- Helle A Praetorius
- Department of Physiology and Biophysics, The Water and Salt Research Center, Aarhus University, Aarhus C, Denmark
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24
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Feranchak AP, Lewis MA, Kresge C, Sathe M, Bugde A, Luby-Phelps K, Antich PP, Fitz JG. Initiation of purinergic signaling by exocytosis of ATP-containing vesicles in liver epithelium. J Biol Chem 2010; 285:8138-47. [PMID: 20071341 DOI: 10.1074/jbc.m109.065482] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Extracellular ATP represents an important autocrine/paracrine signaling molecule within the liver. The mechanisms responsible for ATP release are unknown, and alternative pathways have been proposed, including either conductive ATP movement through channels or exocytosis of ATP-enriched vesicles, although direct evidence from liver cells has been lacking. Utilizing dynamic imaging modalities (confocal and total internal reflection fluorescence microscopy and luminescence detection utilizing a high sensitivity CCD camera) at different scales, including confluent cell populations, single cells, and the intracellular submembrane space, we have demonstrated in a model liver cell line that (i) ATP release is not uniform but reflects point source release by a defined subset of cells; (ii) ATP within cells is localized to discrete zones of high intensity that are approximately 1 mum in diameter, suggesting a vesicular localization; (iii) these vesicles originate from a bafilomycin A(1)-sensitive pool, are depleted by hypotonic exposure, and are not rapidly replenished from recycling of endocytic vesicles; and (iv) exocytosis of vesicles in response to cell volume changes depends upon a complex series of signaling events that requires intact microtubules as well as phosphoinositide 3-kinase and protein kinase C. Collectively, these findings are most consistent with an essential role for exocytosis in regulated release of ATP and initiation of purinergic signaling in liver cells.
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Affiliation(s)
- Andrew P Feranchak
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9030, USA.
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25
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Blum AE, Walsh BC, Dubyak GR. Extracellular osmolarity modulates G protein-coupled receptor-dependent ATP release from 1321N1 astrocytoma cells. Am J Physiol Cell Physiol 2009; 298:C386-96. [PMID: 19907018 DOI: 10.1152/ajpcell.00430.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We previously reported that ATP release from 1321N1 human astrocytoma cells could be stimulated either by activation of G protein-coupled receptors (GPCR) or by hypotonic stress. Cheema et al. (Cheema TA, Ward CE, Fisher SK. J Pharmacol Exp Ther 315: 755-763, 2005) have demonstrated that thrombin activation of protease-activated receptor 1 (PAR1) in 1321N1 cells and primary astrocytes acts synergistically with hypotonic stress to gate the opening of volume-sensitive organic osmolyte and anion channels (VSOAC) and that hypertonic stress strongly inhibits PAR1 gating of VSOAC. We tested the hypothesis that a VSOAC-type permeability might comprise a GPCR-regulated pathway for ATP export by determining whether PAR1-sensitive ATP release from 1321N1 cells is similarly potentiated by hypotonicity but suppressed by hypertonic conditions. Strong hypotonic stress by itself elicited ATP release and positively modulated the response to thrombin. Thrombin-dependent ATP release was also potentiated by mild hypotonic stress that by itself did not stimulate ATP export. Notably, PAR1-sensitive ATP export was greatly inhibited in hypertonic medium. Neither the potency nor efficacy of thrombin as an activator of proximal PAR1 signaling was affected by hypotonicity or hypertonicity. 1,9-Dideoxyforskolin and carbenoxolone similarly attenuated PAR1-dependent ATP release and suppressed the PAR1-independent ATP elicited by strong hypotonic stress. Probenecid attenuated PAR1-stimulated ATP release under isotonic but not mild hypotonic conditions and had no effect on PAR1-independent release stimulated by strong hypotonicity. PAR1-dependent ATP export under all osmotic conditions required concurrent signaling by Ca(2+) mobilization and Rho-GTPase activation. In contrast, PAR1-independent ATP release triggered by strong hypotonicity required neither of these intracellular signals. Thus, we provide the new finding that GPCR-regulated ATP release from 1321N1 astrocytoma cells is remarkably sensitive to both positive and negative modulation by extracellular osmolarity. This supports a model wherein GPCR stimulation and osmotic stress converge on an ATP release pathway in astrocytes that exhibits several features of VSOAC-type channels.
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Affiliation(s)
- Andrew E Blum
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44120, USA
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Woodward HN, Anwar A, Riddle S, Taraseviciene-Stewart L, Fragoso M, Stenmark KR, Gerasimovskaya EV. PI3K, Rho, and ROCK play a key role in hypoxia-induced ATP release and ATP-stimulated angiogenic responses in pulmonary artery vasa vasorum endothelial cells. Am J Physiol Lung Cell Mol Physiol 2009; 297:L954-64. [PMID: 19684203 DOI: 10.1152/ajplung.00038.2009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We recently reported that vasa vasorum expansion occurs in the pulmonary artery (PA) adventitia of chronically hypoxic animals and that extracellular ATP is a pro-angiogenic factor for isolated vasa vasorum endothelial cells (VVEC). However, the sources of extracellular ATP in the PA vascular wall, as well as the molecular mechanisms underlying its release, remain elusive. Studies were undertaken to explore whether VVEC release ATP in response to hypoxia and to determine signaling pathways involved in this process. We found that hypoxia (1-3% O2) resulted in time- and O2-dependent ATP release from VVEC. Preincubation with the inhibitors of vesicular transport (monensin, brefeldin A, and N-ethylmaleimide) significantly decreased ATP accumulation in the VVEC conditioned media, suggesting that hypoxia-induced ATP release occurs through vesicular exocytosis. Additionally, both hypoxia and exogenously added ATP resulted in the activation of PI3K and accumulation of GTP-bound RhoA in a time-dependent manner. Pharmacological inhibition of PI3K and ROCK or knockout of RhoA by small interfering RNA significantly abolished hypoxia-induced ATP release from VVEC. Moreover, RhoA and ROCK play a critical role in ATP-induced increases in VVEC DNA synthesis, migration, and tube formation, indicating a functional contribution of PI3K, Rho, and ROCK to both the autocrine mechanism of ATP release and ATP-mediated angiogenic activation of VVEC. Taken together, our findings provide novel evidence for the signaling mechanisms that link hypoxia-induced increases in extracellular ATP and vasa vasorum expansion.
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Affiliation(s)
- Heather N Woodward
- Department of Pediatrics, 12700 E. 19th Ave., University of Colorado Denver, Research Complex 2, Box B131, Aurora, CO 80045, USA
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Seminario-Vidal L, Kreda S, Jones L, O'Neal W, Trejo J, Boucher RC, Lazarowski ER. Thrombin promotes release of ATP from lung epithelial cells through coordinated activation of rho- and Ca2+-dependent signaling pathways. J Biol Chem 2009; 284:20638-48. [PMID: 19439413 DOI: 10.1074/jbc.m109.004762] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Extracellular ATP controls key aspects of lung function via activation of epithelial cell purinergic receptors, but how ATP is released from cells remains poorly understood. To identify mechanistic components upstream of ATP release, we examined the effect of selected G protein coupled-receptor activation on ATP release from lung epithelial cells. The protease-activated receptor (PAR) agonist thrombin elicited a rapid Ca(2+)-dependent release of ATP from A549 cells. In contrast, the P2Y(2) receptor agonist UTP caused negligible ATP release, despite promoting a robust Ca(2+) response. Agonist-elicited ATP release was associated with Rho activation and was reduced in cells transfected with dominant negative mutants of p115-Rho GEF or RhoA, and by inhibitors of Rho kinase (ROCK). However, RhoA activation alone did not promote ATP release if temporally separated from Ca(2+) mobilization. PAR3 was the only PAR subtype detected in A549 cells by reverse transcription-PCR. Transfection of cells with human PAR3 cDNA increased thrombin-promoted ATP release, inositol phosphate formation, and RhoA activation. Conversely, small interference RNA against PAR3 diminished thrombin-evoked responses. Thrombin-elicited ATP release was accompanied by an enhanced cellular uptake of propidium iodide in a Ca(2+)- and ROCK-dependent manner and was inhibited by connexin/pannexin hemichannel blockers. Our data suggest that thrombin promotes ATP release from A549 cells via Rho- and Ca(2+)-dependent activation of connexin/pannexin hemichannels. The relevance of these findings is highlighted by the observation that exposure of primary cultures of well differentiated human bronchial epithelial cells to thrombin resulted in robust ATP release, which was inhibited by ROCK inhibitors and by connexin/pannexin hemichannel blockers.
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Affiliation(s)
- Lucia Seminario-Vidal
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Praetorius HA, Leipziger J. ATP release from non-excitable cells. Purinergic Signal 2009; 5:433-46. [PMID: 19301146 DOI: 10.1007/s11302-009-9146-2] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2007] [Accepted: 03/03/2008] [Indexed: 02/06/2023] Open
Abstract
All cells release nucleotides and are in one way or another involved in local autocrine and paracrine regulation of organ function via stimulation of purinergic receptors. Significant technical advances have been made in recent years to quantify more precisely resting and stimulated adenosine triphosphate (ATP) concentrations in close proximity to the plasma membrane. These technical advances are reviewed here. However, the mechanisms by which cells release ATP continue to be enigmatic. The current state of knowledge on different suggested mechanisms is also reviewed. Current evidence suggests that two separate regulated modes of ATP release co-exist in non-excitable cells: (1) a conductive pore which in several systems has been found to be the channel pannexin 1 and (2) vesicular release. Modes of stimulation of ATP release are reviewed and indicate that both subtle mechanical stimulation and agonist-triggered release play pivotal roles. The mechano-sensor for ATP release is not yet defined.
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Affiliation(s)
- Helle A Praetorius
- Department of Physiology and Biophysics, Aarhus University, Ole Worms Alle 160, 8000, Aarhus, Denmark
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Abstract
Chemotaxis allows polymorphonuclear neutrophils (PMN) to rapidly reach infected and inflamed sites. However, excessive influx of PMN damages host tissues. Better knowledge of the mechanisms that control PMN chemotaxis may lead to improved treatments of inflammatory diseases. Recent findings suggest that ATP and adenosine are involved in PMN chemotaxis. Therefore, these purinergic signaling processes may be suitable targets for novel therapeutic approaches to ameliorate host tissue damage.
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Affiliation(s)
- W G Junger
- Department of Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, East Stoneman 8M 10C, Boston, Massachusetts 02215, USA.
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Oike M, Watanabe M, Kimura C. Involvement of heparan sulfate proteoglycan in sensing hypotonic stress in bovine aortic endothelial cells. Biochim Biophys Acta Gen Subj 2008; 1780:1148-55. [PMID: 18680786 DOI: 10.1016/j.bbagen.2008.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 07/08/2008] [Accepted: 07/10/2008] [Indexed: 11/25/2022]
Abstract
Hypotonic stress (HTS) induces various responses in vascular endothelium, but the molecules involved in sensing HTS are not known. To investigate a possible role of heparan sulfate proteoglycan (HSPG) in sensing HTS, we compared the responses of control bovine aortic endothelial cells (BAECs) with those of cells treated with heparinase III, which exclusively degrades HSPG. Tyrosine phosphorylation of 125 kDa FAK induced by HTS (-30%) in control cells was abolished in heparinase III-treated BAECs. The amplitude of the volume-regulated anion channel (VRAC) current, whose activation is regulated by tyrosine kinase, was significantly reduced by the treatment with heparinase III. Also, HTS-induced ATP release through the VRAC pore and the concomitant Ca(2+) transients were significantly reduced in the heparinase III-treated BAECs. In contrast, exogenously applied ATP evoked similar Ca(2+) transients in both control and heparinase III-treated BAECs. The transient formation of actin stress fibers induced by HTS in control cells was absent in heparinase III-treated BAECs. Lysophosphatidic acid (LPA) also induced FAK phosphorylation, actin reorganization and ATP release in control BAECs, but heparinase III did not affect these LPA-induced responses. We conclude from these observations that HSPG is one of the sensory molecules of hypotonic cell swelling in BAECs.
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Affiliation(s)
- Masahiro Oike
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
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Koyama T, Kimura C, Hayashi M, Watanabe M, Karashima Y, Oike M. Hypergravity induces ATP release and actin reorganization via tyrosine phosphorylation and RhoA activation in bovine endothelial cells. Pflugers Arch 2008; 457:711-9. [PMID: 18594856 DOI: 10.1007/s00424-008-0544-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 06/05/2008] [Accepted: 06/10/2008] [Indexed: 11/24/2022]
Abstract
Mechanical stresses regulate physiological and pathological functions of vascular endothelial cells. We examined, in this study, the effects of hypergravity on endothelial functions. Hypergravity (3 G) applied by low speed centrifuge immediately induced a membrane translocation of small G-protein RhoA and tyrosine phosphorylation of 125 kDa FAK in bovine aortic endothelial cells (BAECs). Hypergravity also induced a transient reorganization of actin fibers in 3 min, which was inhibited by Rho-kinase inhibitor (Y27632) and tyrosine kinase inhibitors (herbimycin A and tyrphostin 46). Furthermore, the extracellular ATP concentration ([ATP]o) was increased by 2 G and 3 G hypergravity in 5 min, and the inhibitors of Rho-kinase, tyrosine kinase, and volume-regulated anion channels (VRAC; verapamil, tamoxifen and fluoxetine) significantly suppressed [ATP]o elevation. Application of 3 G hypergravity for 1 h increased the nuclear uptake of BrdU, which was inhibited by Rho-kinase inhibitor and VARC inhibitors. Furthermore, intermittent application of 3 G hypergravity for 1 or 2 h/day stimulated endothelial migration in 5 days, and this was inhibited by suramin, a P2 antagonist. Collectively, these results indicate that hypergravity induces ATP release and actin reorganization via RhoA activation and FAK phosphorylation, thereby activating cell proliferation and migration in BAECs. These also suggest that gravity can be regarded as an extracorporeal signal that could significantly affect endothelial functions.
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Affiliation(s)
- Tetsuya Koyama
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
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Ohta Y, Hayashi M, Kanemaru T, Abe K, Ito Y, Oike M. Dual modulation of airway smooth muscle contraction by Th2 cytokines via matrix metalloproteinase-1 production. THE JOURNAL OF IMMUNOLOGY 2008; 180:4191-9. [PMID: 18322231 DOI: 10.4049/jimmunol.180.6.4191] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Altered contractility of airway smooth muscle (SM) is one of the main causes of allergic asthma, in which the predominance of Th2 over Th1 cytokines plays a central role. In the present study, we examine the effects of Th2 cytokines on airway SM contraction. Treatment with a low concentration of IL-4 (0.2 ng/ml) for 6 h augmented, whereas higher concentrations (2-20 ng/ml) inhibited, agonist-induced contractions of collagen gels containing bovine tracheal SM cells. Another Th2 cytokine (IL-13) showed an augmentation of gel contraction in the concentration range of 20-200 ng/ml. IL-4 and IL-13 increased mRNA expression and protein secretion of matrix metalloproteinase (MMP)-1, but these cytokines did not affect Ca(2+)-mobilizing properties and phosphorylation levels of myosin L chain in bovine tracheal SM cells. These changes were sensitive to wortmannin, an inhibitor of PI3K, but not to leflunomide, an inhibitor of STAT6. Scanning electron microscope observation revealed that collagen fibers twining around SM cells were completely dissolved in 20 ng/ml IL-4-treated gels and reorganized into basket-like structure in 20 ng/ml IL-13-treated gels. Exogenous application of high and low concentrations of MMP-1 also induced the inhibition and augmentation of gel contraction, respectively. Furthermore, nonselective MMP inhibitor galardin suppressed the effects of IL-4 and IL-13 on gel contraction, and MMP-1-targeted small-interfering RNA reversed the inhibitory effects of IL-4 on gel contraction to the augmentation. This indicates that Th2 cytokines modulate airway contraction without affecting cellular contractility but by secreting MMP-1 from the SM cells via PI3K activation and changing cell-to-matrix interactions.
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Affiliation(s)
- Yoshinori Ohta
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Franco R, Panayiotidis MI, de la Paz LDO. Autocrine signaling involved in cell volume regulation: the role of released transmitters and plasma membrane receptors. J Cell Physiol 2008; 216:14-28. [PMID: 18300263 DOI: 10.1002/jcp.21406] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cell volume regulation is a basic homeostatic mechanism transcendental for the normal physiology and function of cells. It is mediated principally by the activation of osmolyte transport pathways that result in net changes in solute concentration that counteract cell volume challenges in its constancy. This process has been described to be regulated by a complex assortment of intracellular signal transduction cascades. Recently, several studies have demonstrated that alterations in cell volume induce the release of a wide variety of transmitters including hormones, ATP and neurotransmitters, which have been proposed to act as extracellular signals that regulate the activation of cell volume regulatory mechanisms. In addition, changes in cell volume have also been reported to activate plasma membrane receptors (including tyrosine kinase receptors, G-protein coupled receptors and integrins) that have been demonstrated to participate in the regulatory process of cell volume. In this review, we summarize recent studies about the role of changes in cell volume in the regulation of transmitter release as well as in the activation of plasma membrane receptors and their further implications in the regulation of the signaling machinery that regulates the activation of osmolyte flux pathways. We propose that the autocrine regulation of Ca2+-dependent and tyrosine phosphorylation-dependent signaling pathways by the activation of plasma membrane receptors and swelling-induced transmitter release is necessary for the activation/regulation of osmolyte efflux pathways and cell volume recovery. Furthermore, we emphasize the importance of studying these extrinsic signals because of their significance in the understanding of the physiology of cell volume regulation and its role in cell biology in vivo, where the constraint of the extracellular space might enhance the autocrine or even paracrine signaling induced by these released transmitters.
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Affiliation(s)
- Rodrigo Franco
- Laboratory of Cell Biology and Signal Transduction, Biomedical Research Unit, FES-Iztacala, UNAM, Mexico.
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Blum AE, Joseph SM, Przybylski RJ, Dubyak GR. Rho-family GTPases modulate Ca(2+) -dependent ATP release from astrocytes. Am J Physiol Cell Physiol 2008; 295:C231-41. [PMID: 18495810 DOI: 10.1152/ajpcell.00175.2008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Previously, we reported that activation of G protein-coupled receptors (GPCR) in 1321N1 human astrocytoma cells elicits a rapid release of ATP that is partially dependent on a G(q)/phophospholipase C (PLC)/Ca(2+) mobilization signaling cascade. In this study we assessed the role of Rho-family GTPase signaling as an additional pathway for the regulation of ATP release in response to activation of protease-activated receptor-1 (PAR1), lysophosphatidic acid receptor (LPAR), and M3-muscarinic (M3R) GPCRs. Thrombin (or other PAR1 peptide agonists), LPA, and carbachol triggered quantitatively similar Ca(2+) mobilization responses, but only thrombin and LPA caused rapid accumulation of active GTP-bound Rho. The ability to elicit Rho activation correlated with the markedly higher efficacy of thrombin and LPA, relative to carbachol, as ATP secretagogues. Clostridium difficile toxin B and Clostridium botulinum C3 exoenzyme, which inhibit Rho-GTPases, attenuated the thrombin- and LPA-stimulated ATP release but did not decrease carbachol-stimulated release. Thus the ability of certain G(q)-coupled receptors to additionally stimulate Rho-GTPases acts to strongly potentiate a Ca(2+)-activated ATP release pathway. However, pharmacological inhibition of Rho kinase I/II or myosin light chain kinase did not attenuate ATP release. PAR1-induced ATP release was also reduced twofold by brefeldin treatment suggesting the possible mobilization of Golgi-derived, ATP-containing secretory vesicles. ATP release was also markedly repressed by the gap junction channel inhibitor carbenoxolone in the absence of any obvious thrombin-induced change in membrane permeability indicative of hemichannel gating.
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Affiliation(s)
- Andrew E Blum
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Gerasimovskaya EV, Woodward HN, Tucker DA, Stenmark KR. Extracellular ATP is a pro-angiogenic factor for pulmonary artery vasa vasorum endothelial cells. Angiogenesis 2007; 11:169-82. [PMID: 18071915 PMCID: PMC2480488 DOI: 10.1007/s10456-007-9087-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2007] [Accepted: 11/26/2007] [Indexed: 12/22/2022]
Abstract
Expansion of the vasa vasorum network has been observed in a variety of systemic and pulmonary vascular diseases. We recently reported that a marked expansion of the vasa vasorum network occurs in the pulmonary artery adventitia of chronically hypoxic calves. Since hypoxia has been shown to stimulate ATP release from both vascular resident as well as circulatory blood cells, these studies were undertaken to determine if extracellular ATP exerts angiogenic effects on isolated vasa vasorum endothelial cells (VVEC) and/or if it augments the effects of other angiogenic factors (VEGF and basic FGF) known to be present in the hypoxic microenvironment. We found that extracellular ATP dramatically increases DNA synthesis, migration, and rearrangement into tube-like networks on Matrigel in VVEC, but not in pulmonary artery (MPAEC) or aortic (AOEC) endothelial cells obtained from the same animals. Extracellular ATP potentiated the effects of both VEGF and bFGF to stimulate DNA synthesis in VVEC but not in MPAEC and AOEC. Analysis of purine and pyrimidine nucleotides revealed that ATP, ADP and MeSADP were the most potent in stimulating mitogenic responses in VVEC, indicating the involvement of the family of P2Y1-like purinergic receptors. Using pharmacological inhibitors, Western blot analysis, and Phosphatidylinositol-3 kinase (PI3K) in vitro kinase assays, we found that PI3K/Akt/mTOR and ERK1/2 play a critical role in mediating the extracellular ATP-induced mitogenic and migratory responses in VVEC. However, PI3K/Akt and mTOR/p70S6K do not significantly contribute to extracellular ATP-induced tube formation on Matrigel. Our studies indicate that VVEC, isolated from the sites of active angiogenesis, exhibit distinct functional responses to ATP, compared to endothelial cells derived from large pulmonary or systemic vessels. Collectively, our data support the idea that extracellular ATP participates in the expansion of the vasa vasorum that can be observed in hypoxic conditions.
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Affiliation(s)
- Evgenia V Gerasimovskaya
- Department of Pediatrics, University of Colorado at Denver and Health Sciences Center, B131, 4200 East 9th Ave, Denver, CO 80262, USA.
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Tatur S, Groulx N, Orlov SN, Grygorczyk R. Ca2+-dependent ATP release from A549 cells involves synergistic autocrine stimulation by coreleased uridine nucleotides. J Physiol 2007; 584:419-35. [PMID: 17702822 PMCID: PMC2277166 DOI: 10.1113/jphysiol.2007.133314] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Extracellular ATP is a potent surfactant secretagogue but its origin in the alveolus, its mechanism(s) of release and its regulatory pathways remain unknown. Previously, we showed that hypotonic swelling of alveolar A549 cells induces Ca(2+)-dependent secretion of several adenosine and uridine nucleotides, implicating regulated exocytosis. In this study, we examined sources of Ca(2+) for the elevation of intracellular Ca(2+) concentration ([Ca(2+)](i)) evoked by acute 50% hypotonic stress and the role of autocrine purinergic signalling in Ca(2+)-dependent ATP release. We found that ATP release does not directly involve Ca(2+) influx from extracellular spaces, but depends entirely on Ca(2+) mobilization from intracellular stores. The [Ca(2+)](i) response consisted of slowly rising elevation, representing mobilization from thapsigargin (TG)-insensitive stores and a superimposed rapid spike due to Ca(2+) release from TG-sensitive endoplasmic reticulum (ER) Ca(2+) stores. The latter could be abolished by hydrolysis of extracellular triphospho- and diphosphonucleotides with apyrase; blocking P2Y(2)/P2Y(6) receptors of A549 cells with suramin; blocking UDP receptors (P2Y(6)) with pyridoxal phosphate 6-azophenyl-2',4'-disulfonic acid (PPADS); emptying TG-sensitive stores downstream with TG or caffeine in Ca(2+)-free extracellular solution; or blocking the Ca(2+)-release inositol 1,4,5-triphosphate receptor channel of the ER with 2-aminoethyldiphenylborinate. These data demonstrate that the rapid [Ca(2+)](i) spike results from the autocrine stimulation of IP(3)/Ca(2+)-coupled P2Y, predominantly P2Y(6), receptors, accounting for approximately 70% of total Ca(2+)-dependent ATP release evoked by hypotonic shock. Our study reveals a novel paradigm in which stress-induced ATP release from alveolar cells is amplified by the synergistic autocrine/paracrine action of coreleased uridine and adenosine nucleotides. We suggest that a similar mechanism of purinergic signal propagation operates in other cell types.
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Affiliation(s)
- Sabina Tatur
- Centre hospitalier de l'Université de Montréal - Hôtel-Dieu, 3850 Saint-Urbain, Montréal, Québec, Canada
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Raoux M, Colomban C, Delmas P, Crest M. The Amine-Containing Cutaneous Irritant Heptylamine Inhibits the Volume-Regulated Anion Channel and Mobilizes Intracellular Calcium in Normal Human Epidermal Keratinocytes. Mol Pharmacol 2007; 71:1685-94. [PMID: 17384225 DOI: 10.1124/mol.106.033324] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Many amines are skin irritants and cause contact dermatitis. However, little is known about their mechanisms of action in keratinocytes except that they induce the release of the inflammatory mediators cytokines and ATP. Here, we tested whether volume-regulated anion channels (VRACs) in primary cultures of normal human epidermal keratinocytes are modulated by the referenced amine-containing cutaneous irritant heptylamine. Under isotonic conditions, we isolated the VRAC current (I(VRAC)) from other conductances using a high Ca(2+)-buffering internal solution. I(VRAC) ran up after patch rupturing and reached a plateau within 15 min. It was reversibly and dose-dependently inhibited by heptylamine with an IC(50) value of 260 microM. Cell-swelling caused by the application of a hypotonic solution increased 2.7-fold I(VRAC) and reduced the inhibition of VRAC by heptylamine with a dose-response curve shifted approximately 10-fold to the right. In addition, we showed, using cell-attached patch recordings, that adding heptylamine to the bath inhibited VRAC activity. This suggests that heptylamine diffuses into the membrane to inhibit VRAC. Finally, we demonstrated that heptylamine induced Ca(2+)-store depletion and that VRAC inhibition was not caused by the increase in cytosolic Ca(2+). Taken together, these results identify heptylamine as a blocker of VRAC and suggest that Ca(2+)-store depletion may be involved in mechanisms of irritant contact dermatitis caused by heptylamine.
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Affiliation(s)
- Matthieu Raoux
- Laboratoire de Neurophysiologie Cellulaire, CNRS UMR 6150, IFR Jean Roche, Faculté de Médecine, Université de la Méditerranée, Boulevard Pierre Dramard, 13916, Marseille Cedex 20, France
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Hirakawa M, Karashima Y, Watanabe M, Kimura C, Ito Y, Oike M. Protein kinase A inhibits lysophosphatidic acid-induced migration of airway smooth muscle cells. J Pharmacol Exp Ther 2007; 321:1102-8. [PMID: 17347321 DOI: 10.1124/jpet.106.118042] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lysophosphatidic acid (LPA) is a bioactive phospholipid that is released from activated platelets and affects contractile properties of airway smooth muscle cells. However, possible roles of LPA on cell migration, one of the initial events of airway remodeling, are not clarified. This study aimed to examine the effects of LPA on migration and actin fiber formation in bovine tracheal smooth muscle cells (BTSMCs). Random and oriented cell migrations were examined with wound assay and Boyden chamber assay, respectively. Cytosolic actin fibers were stained with rhodamine-phalloidin. Membrane translocation of RhoA, a hallmark of RhoA activation, was assessed by Western blotting. LPA augmented the migration of BTSMCs from wounded confluent monolayer but did not accelerate the chemotactic migration toward LPA. LPA also induced a transient actin reorganization and RhoA activation. Dense actin fibers were observed mainly in the wound edge but not in migrated cells, thereby suggesting the role of actin reorganization in the initiation of cell migration. LPA-induced actin fiber formation was blocked by Y27632 [R-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexane carboxamide], an inhibitor of Rho kinase. Effects of LPA on migration and actin fiber formation were also inhibited by cAMP-elevating agents, i.e., dibutyryl cAMP, forskolin, isoproterenol, and theophylline. KT5720 (9S,10S,12R)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid hexyl ester], a protein kinase A (PKA) inhibitor, reversed the inhibitory actins of cAMP on LPA-induced responses. These results indicate that LPA induces cAMP/PKA-sensitive, RhoA-mediated random migration of BTSMCs. Regulation of this mechanism would be beneficial for the control of airway remodeling.
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Affiliation(s)
- Masakazu Hirakawa
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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Watanabe M, Oike M, Ohta Y, Ito Y. Long-term treatment with TGFbeta1 impairs mechanotransduction in bovine aortic endothelial cells. Br J Pharmacol 2007; 150:424-33. [PMID: 17220908 PMCID: PMC2189726 DOI: 10.1038/sj.bjp.0707123] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND AND PURPOSE Vascular endothelial cells play a role in the physiological response to mechanical stress. Transforming growth factor beta1 (TGFbeta1) induces morphological changes in endothelial cells, and this may alter their mechanosensitive responses. The aim of this study was to examine the effects of TGFbeta1 on hypotonic stress (HTS)-induced responses in bovine aortic endothelial cells (BAECs). EXPERIMENTAL APPROACH Cultured BAECs were treated with 3 ng ml(-1) TGFbeta1 for 24 h (24h-TGFbeta1) or 7 days (7d-TGFbeta1). Cytosolic actin fibres were stained with rhodamine-phalloidin. Intracellular Ca2+ concentration was measured using fura2. Tyrosine phosphorylation and RhoA expression were assessed by Western blotting. Expression of RhoA mRNA was assessed by real-time PCR. KEY RESULTS BAECs developed pseudopod-like processes within 24 h and showed a fibroblast-like appearance after 7 days. HTS induced Ca2+ transients via endogenous ATP release in both control and 24h-TGFbeta1 BAECs but not in 7d-TGFbeta1 BAECs. We have previously shown that HTS-induced ATP release is mediated by sequential activation of RhoA and tyrosine kinases. The basal amount of membrane-bound RhoA was significantly lower in 7d-TGFbeta1 than in 24h-TGFbeta1 or control BAECs. HTS increased the membrane-bound RhoA to the same fractional level in 24h-TGFbeta1 and control BAECs, but its net maximal amount was significantly lower in 7d-TGFbeta1. HTS-induced downstream signals of RhoA activation, i.e. the tyrosine phosphorylation of FAK and paxillin, were markedly suppressed in 7d-TGFbeta1 BAECs. CONCLUSIONS AND IMPLICATIONS These results indicate that long-term treatment with TGFbeta1 does not impair mechanoreception in BAECs but impairs mechanotransduction by affecting RhoA membrane translocation.
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Affiliation(s)
- M Watanabe
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
| | - M Oike
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
- Author for correspondence:
| | - Y Ohta
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
| | - Y Ito
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
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Pangrsic T, Potokar M, Haydon PG, Zorec R, Kreft M. Astrocyte swelling leads to membrane unfolding, not membrane insertion. J Neurochem 2007; 99:514-23. [PMID: 17029603 DOI: 10.1111/j.1471-4159.2006.04042.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mechanisms mediating the release of chemical transmitters from astrocytes are the subject of intense research. Recent experiments have shown that hypotonic conditions stimulate the release of glutamate and ATP from astrocytes, but a mechanistic understanding of this process is not available. To determine whether hypotonicity activates the process of regulated exocytosis, we monitored membrane capacitance by the whole-cell patch-clamp technique whilst a hypotonic medium was applied to cultured astrocytes. If exocytosis is triggered under hypotonic conditions, as it is following increases in cytosolic calcium, a net increase in membrane surface area, monitored by measuring the whole-cell membrane capacitance, is expected. Simultaneous measurements of cell size and whole-cell membrane conductance and surface area demonstrated that hypotonic medium (210 mOsm for 200 s) resulted in an increase in membrane conductance and in the swelling of cultured astrocytes by an average of 40%, as monitored by cell cross-sectional area, but without any corresponding change in membrane surface area. As we have demonstrated that capacitance measurements have the sensitivity to detect increases in cell surface area as small as 0.5%, we conclude that cell swelling occurs via an exocytosis-independent mechanism, probably involving the unfolding of the plasma membrane.
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Affiliation(s)
- Tina Pangrsic
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Medical Faculty, University of Ljubljana, Ljubljana, Slovenia
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Malek AM, Xu C, Kim ES, Alper SL. Hypertonicity triggers RhoA-dependent assembly of myosin-containing striated polygonal actin networks in endothelial cells. Am J Physiol Cell Physiol 2006; 292:C1645-59. [PMID: 17192281 DOI: 10.1152/ajpcell.00533.2006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Endothelial cells respond to mechanical stresses of the circulation with cytoskeletal rearrangements such as F-actin stress fiber alignment along the axis of fluid flow. Endothelial cells are exposed to hypertonic stress in the renal medulla or during mannitol treatment of cerebral edema. We report here that arterial endothelial cells exposed to hypertonic stress rearranged F-actin into novel actin-myosin II fibers with regular 0.5-microm striations, in which alpha-actinin colocalizes with actin. These striated fibers assembled over hours into three-dimensional, irregular, polygonal actin networks most prominent at the cell base, and occasionally surrounding the nucleus in a geodesic-like structure. Hypertonicity-induced assembly of striated polygonal actin networks was inhibited by cytochalasin D, blebbistatin, cell ATP depletion, and intracellular Ca(2+) chelation but did not require intact microtubules, regulatory volume increase, or de novo RNA or protein synthesis. Striated polygonal actin network assembly was insensitive to inhibitors of MAP kinases, tyrosine kinases, or phosphatidylinositol 3-kinase, but was prevented by C3 exotoxin, by the RhoA kinase inhibitor Y-27632, and by overexpressed dominant-negative RhoA. In contrast, overexpression of dominant-negative Rac or of dominant-negative cdc42 cDNAs did not prevent striated polygonal actin network assembly. The actin networks described here are novel in structure, as striated actin-myosin structures in nonmuscle cells, as a cellular response to hypertonicity, and as a cytoskeletal regulatory function of RhoA. Endothelial cells may use RhoA-dependent striated polygonal actin networks, possibly in concert with cytoskeletal load-bearing elements, as a contractile, tension-generating component of their defense against isotropic compressive forces.
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Affiliation(s)
- Adel M Malek
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA.
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Takii M, Ishikawa T, Tsuda H, Kanatani K, Sunouchi T, Kaneko Y, Nakayama K. Involvement of stretch-activated cation channels in hypotonically induced insulin secretion in rat pancreatic β-cells. Am J Physiol Cell Physiol 2006; 291:C1405-11. [PMID: 16822943 DOI: 10.1152/ajpcell.00519.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In isolated rat pancreatic β-cells, hypotonic stimulation elicited an increase in cytosolic Ca2+ concentration ([Ca2+]c) at 2.8 mM glucose. The hypotonically induced [Ca2+]c elevation was significantly suppressed by nicardipine, a voltage-dependent Ca2+ channel blocker, and by Gd3+, amiloride, 2-aminoethoxydiphenylborate, and ruthenium red, all cation channel blockers. In contrast, the [Ca2+]c elevation was not inhibited by suramin, a P2 purinoceptor antagonist. Whole cell patch-clamp analyses showed that hypotonic stimulation induced membrane depolarization of β-cells and produced outwardly rectifying cation currents; Gd3+ inhibited both responses. Hypotonic stimulation also increased insulin secretion from isolated rat islets, and Gd3+ significantly suppressed this secretion. Together, these results suggest that osmotic cell swelling activates cation channels in rat pancreatic β-cells, thereby causing membrane depolarization and subsequent activation of voltage-dependent Ca2+ channels and thus elevating insulin secretion.
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Affiliation(s)
- Miki Takii
- Department of Cellular and Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka City, Shizuoka, Japan
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Hirakawa M, Oike M, Watanabe M, Karashima Y, Ito Y. Pivotal role of integrin alpha5beta1 in hypotonic stress-induced responses of human endothelium. FASEB J 2006; 20:1992-9. [PMID: 17012251 DOI: 10.1096/fj.05-5580com] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have previously reported that both hypotonic stress (HTS) and lysophosphatidic acid (LPA) induce ATP release and a transient reorganization of actin through sequential activation of RhoA/Rho-kinase and focal adhesion kinase F-actin (FAK)/paxillin in human umbilical cord vein endothelial cells (HUVECs). LPA is known to induce the activation of RhoA via its specific receptors, but the mechanisms by which HTS initiates these intracellular signals are not known. The present study aimed to identify the molecule(s) that are unique to the sensing and/or transducing the mechanical stress. Reverse transcriptase-polymerase chain reaction revealed the expression of several integrin subunits in HUVECs. Anti-integrin alpha5beta1 antibody (Ab), but not anti-integrin alpha2, alpha6, alpha v, or beta4 antibodies, inhibited HTS-induced RhoA translocation, tyrosine phosphorylation of FAK and paxillin, ATP release, and actin reorganization. However, the LPA-induced ATP release and actin reorganization were not inhibited by any of these anti-integrin antibodies, indicating that integrin alpha5beta1 plays a pivotal role in the HTS-induced but not in the LPA-induced responses. It is therefore reasonable to assume that this particular subtype of integrin is involved in the initiation of the responses induced by mechanical stimuli in HUVECs.
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Affiliation(s)
- Masakazu Hirakawa
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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Watanabe M, Oike M, Ohta Y, Nawata H, Ito Y. Sustained contraction and loss of NO production in TGFbeta1-treated endothelial cells. Br J Pharmacol 2006; 149:355-64. [PMID: 16967050 PMCID: PMC1978430 DOI: 10.1038/sj.bjp.0706883] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND AND PURPOSE Transforming growth factor beta1 (TGFbeta1) is generated in atherosclerotic and injured vessel walls. We examined whether the endothelial-to-mesenchymal transdifferentiation induced by TGFbeta1 affects endothelial functions. EXPERIMENTAL APPROACH Bovine aortic endothelial cells (BAECs) were treated with 3 ng ml(-1) TGFbeta1 for 7 days. Contraction of TGFbeta1-treated BAECs was assessed by collagen gel contraction assay. Protein expression and phosphorylation were assessed by Western blotting. Intracellular Ca2+ concentration and NO production were measured using fura2 and DAF-2, respectively. KEY RESULTS TGFbeta1-treated BAECs showed dense actin fibers and expressed smooth muscle marker proteins; they also changed into smooth muscle-like, spindle-shaped cells in collagen gel cultures. ATP (10 microM) induced a gradual contraction of collagen gels containing TGFbeta1-treated BAECs but not of gels containing control BAECs. ATP-induced contraction of TGFbeta1-treated BAECs was not reversed by the removal of ATP but was partially suppressed by a high concentration of sodium nitroprusside (1 microM). TGFbeta1-treated BAECs showed sustained phosphorylation of myosin light chain in response to ATP and low levels of basal MYPT1 expression. ATP-induced Ca2+ transients as well as eNOS protein expression were not affected by TGFbeta1 in BAECs. However, ATP-induced NO production was significantly reduced in TGFbeta1-treated BAECs. Anti-TGFbeta1 antibody abolished all of these TGFbeta1-induced changes in BAECs. CONCLUSIONS AND IMPLICATIONS Mesenchymal transdifferentiation induced by TGFbeta1 leads to sustained contraction and reduced NO production in endothelial cells. Such effects, therefore, would not be beneficial for vascular integrity.
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Affiliation(s)
- M Watanabe
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
| | - M Oike
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
- Author for correspondence:
| | - Y Ohta
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
| | - H Nawata
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
| | - Y Ito
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
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Abbracchio MP, Burnstock G, Boeynaems JM, Barnard EA, Boyer JL, Kennedy C, Knight GE, Fumagalli M, Gachet C, Jacobson KA, Weisman GA. International Union of Pharmacology LVIII: update on the P2Y G protein-coupled nucleotide receptors: from molecular mechanisms and pathophysiology to therapy. Pharmacol Rev 2006; 58:281-341. [PMID: 16968944 PMCID: PMC3471216 DOI: 10.1124/pr.58.3.3] [Citation(s) in RCA: 987] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
There have been many advances in our knowledge about different aspects of P2Y receptor signaling since the last review published by our International Union of Pharmacology subcommittee. More receptor subtypes have been cloned and characterized and most orphan receptors de-orphanized, so that it is now possible to provide a basis for a future subdivision of P2Y receptor subtypes. More is known about the functional elements of the P2Y receptor molecules and the signaling pathways involved, including interactions with ion channels. There have been substantial developments in the design of selective agonists and antagonists to some of the P2Y receptor subtypes. There are new findings about the mechanisms underlying nucleotide release and ectoenzymatic nucleotide breakdown. Interactions between P2Y receptors and receptors to other signaling molecules have been explored as well as P2Y-mediated control of gene transcription. The distribution and roles of P2Y receptor subtypes in many different cell types are better understood and P2Y receptor-related compounds are being explored for therapeutic purposes. These and other advances are discussed in the present review.
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Affiliation(s)
- Maria P Abbracchio
- Department of Pharmacological Sciences, University of Milan, Milan, Italy
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Di Ciano-Oliveira C, Thirone ACP, Szászi K, Kapus A. Osmotic stress and the cytoskeleton: the R(h)ole of Rho GTPases. Acta Physiol (Oxf) 2006; 187:257-72. [PMID: 16734763 DOI: 10.1111/j.1748-1716.2006.01535.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Hyperosmotic stress initiates a variety of compensatory and adaptive responses, which either serve to restore near-normal volume or remodel and reinforce the cell structure to withstand the physical challenge. The latter response is brought about by the reorganization of the cytoskeleton; however, the underlying mechanisms are not well understood. Recent research has provided major breakthroughs in our knowledge about the link between message and structure, i.e. between signalling and cytoskeletal remodelling, predominantly in the context of cell migration. The major components of this progress are the in-depth characterization of Rho family small GTPases, master regulators of the cytoskeleton, and the discovery of the actin-related protein 2/3 complex, a signalling-sensitive structural element of the actin polymerization machinery. The primary aim of this review is to find the place of these novel and crucial players in osmotically induced (volume-dependent) remodelling of the cytoskeleton. We aim to address three questions: (1) What are the major structural changes in the cytoskeleton under hyperosmotic conditions? (2) Are the Rho family small GTPases (Rho, Rac and Cdc42) regulated by osmotic stress, and if so, by what mechanisms? (3) Are Rho GTPases involved, as mediators, in major adaptive responses, including cytoskeleton rearrangement, changes in ion transport and genetic reprogramming? Our answers will show how fragmentary our current knowledge is in these areas. Therefore, this overview has been written with the hardly disguised intention that it might foster further research in this field by highlighting some intriguing questions.
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Affiliation(s)
- C Di Ciano-Oliveira
- The St Michael's Hospital Research Institute, Department of Surgery, University of Toronto, Toronto, ON, Canada
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Ollivier H, Pichavant K, Puill-Stephan E, Roy S, Calvès P, Nonnotte L, Nonnotte G. Volume regulation following hyposmotic shock in isolated turbot (Scophthalmus maximus) hepatocytes. J Comp Physiol B 2006; 176:393-403. [PMID: 16395590 DOI: 10.1007/s00360-005-0061-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 11/28/2005] [Accepted: 12/06/2005] [Indexed: 10/25/2022]
Abstract
Regulatory volume decrease (RVD) following hyposmotic stimulation was studied in isolated turbot, Scophthalmus maximus, hepatocytes. Exposed to a reduced osmolality (from 320 to 240 mosm kg(-1)), cells first swelled and then exhibited a RVD. Volume regulation was significantly inhibited in presence of NPPB, 9-AC, acetazolamide, DIDS and barium. Taken together, these results could suggest that RVD operated via separate K+ and Cl- channels and probably Cl-/HCO3(-) exchanger in turbot hepatocytes. The K+/Cl- cotransporter could also be involved as furosemide and DIOA strongly inhibited the process whereas NEM, a K+/Cl- cotransporter activator, added under isosmotic conditions, led to cell shrinkage. RVD in turbot hepatocytes appeared also to depend on proteins p38 MAP kinase and tyrosine kinase but not on proteins ERK 1/2. Arachidonic acid and leukotrienes could also be involved since inhibition of synthesis of both these compounds by quinacrine and NDGA, respectively, inhibited the volume regulation. Likewise, Ca2+ has been proved to be an essential messenger as RVD was prevented in absence of Ca2+. Finally, this work provides bases for novel studies on cell volume regulation in marine teleosteans.
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Affiliation(s)
- Hélène Ollivier
- Unité de Physiologie Comparée et Intégrative, U.F.R. Sciences et Techniques, 6 Avenue Le Gorgeu CS 93837, 29238, Brest-Cedex 3, France.
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Costessi A, Pines A, D'Andrea P, Romanello M, Damante G, Cesaratto L, Quadrifoglio F, Moro L, Tell G. Extracellular nucleotides activate Runx2 in the osteoblast-like HOBIT cell line: a possible molecular link between mechanical stress and osteoblasts' response. Bone 2005; 36:418-32. [PMID: 15777650 DOI: 10.1016/j.bone.2004.10.016] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Revised: 10/18/2004] [Accepted: 10/18/2004] [Indexed: 10/25/2022]
Abstract
Dynamic mechanical loading increases bone density and strength and promotes osteoblast proliferation, differentiation and matrix production, by acting at the gene expression level. Molecular mechanisms through which mechanical forces are conversed into biochemical signalling in bone are still poorly understood. A growing body of evidence point to extracellular nucleotides (i.e., ATP and UTP) as soluble factors released in response to mechanical stimulation in different cell systems. Runx2, a fundamental transcription factor involved in controlling osteoblasts differentiation, has been recently identified as a target of mechanical signals in osteoblastic cells. We tested the hypothesis that these extracellular nucleotides could be able to activate Runx2 in the human osteoblastic HOBIT cell line. We found that ATP and UTP treatments, as well as hypotonic stress, promote a significant stimulation of Runx2 DNA-binding activity via a mechanism involving PKC and distinct mitogen-activated protein kinase cascades. In fact, by using the specific inhibitors SB203580 (specific for p38 MAPK) and PD98059 (specific for ERK-1/2 MAPK), we found that ERK-1/2, but not p38, play a major role in Runx2 activation. On the contrary, another important transcription factor, i.e., Egr-1, that we previously demonstrated being activated by extracellular released nucleotides in this osteoblastic cell line, demonstrated to be susceptible to both ERK-1/2 and p38 kinases. These data suggest a possible differential involvement of these two transcription factors in response to extracellularly released nucleotides. The biological relevance of our data is strengthened by the finding that a target gene of Runx2, i.e., Galectin-3, is up-regulated by ATP stimulation of HOBIT cells with a comparable kinetic of that found for Runx2. Since it is known that osteocytes are the primary mechanosensory cells of the bone, we hypothesize that they may signal mechanical loading to osteoblasts through release of extracellular nucleotides. Altogether, these data suggest a molecular mechanism explaining the purinoreceptors-mediated activation of specific gene expression in osteoblasts and could be of help in setting up new pharmacological strategies for the intervention in bone loss pathologies.
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Affiliation(s)
- Adalberto Costessi
- Department of Biomedical Sciences and Technologies, University of Udine, 33100 Udine, Italy
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Sabirov RZ, Okada Y. ATP-conducting maxi-anion channel: a new player in stress-sensory transduction. ACTA ACUST UNITED AC 2004; 54:7-14. [PMID: 15040843 DOI: 10.2170/jjphysiol.54.7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The regulated release of ATP is a fundamental process in cell-to-cell signaling. The electrogenic translocation of ATP via an anion channel has been suggested as one possible mechanism of the release. In this review, we survey possible candidate channels for this pathway. The maxi-anion channel characterized by an exceedingly large unitary conductance has been a stray channel with regard to its function. A newly discovered property, its ATP conductivity and its activation in response to stress signals, indicates that this channel has a central role in stress-sensory transduction for cell volume regulation and tubuloglomerular feedback.
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Affiliation(s)
- Ravshan Z Sabirov
- Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki, 444-8585 Japan.
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Gerasimovskaya EV, Tucker DA, Weiser-Evans M, Wenzlau JM, Klemm DJ, Banks M, Stenmark KR. Extracellular ATP-induced proliferation of adventitial fibroblasts requires phosphoinositide 3-kinase, Akt, mammalian target of rapamycin, and p70 S6 kinase signaling pathways. J Biol Chem 2004; 280:1838-48. [PMID: 15522879 DOI: 10.1074/jbc.m409466200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Extracellular nucleotides are increasingly recognized as important regulators of growth in a variety of cell types. Recent studies have demonstrated that extracellular ATP is a potent inducer of fibroblast growth acting, at least in part, through an ERK1/2-dependent signaling pathway. However, the contributions of additional signaling pathways to extracellular ATP-mediated cell proliferation have not been defined. By using both pharmacologic and genetic approaches, we found that in addition to ERK1/2, phosphatidylinositol 3-kinase (PI3K), Akt, mammalian target of rapamycin (mTOR), and p70 S6K-dependent signaling pathways are required for ATP-induced proliferation of adventitial fibroblasts. We found that extracellular ATP acting in part through G(i) proteins increased PI3K activity in a time-dependent manner and transient phosphorylation of Akt. This PI3K pathway is not involved in ATP-induced activation of ERK1/2, implying activation of independent parallel signaling pathways by ATP. Extracellular ATP induced dramatic increases in mTOR and p70 S6K phosphorylation. This activation of the mTOR/p70 S6 kinase (p70 S6K) pathway in response to ATP is because of independent contributions of PI3K/Akt and ERK1/2 pathways, which converge on the level of p70 S6K. ATP-dependent activation of mTOR and p70 S6K also requires additional signaling inputs perhaps from pathways operating through Galpha or Gbetagamma subunits. Collectively, our data demonstrate that ATP-induced adventitial fibroblast proliferation requires activation and interaction of multiple signaling pathways such as PI3K, Akt, mTOR, p70 S6K, and ERK1/2 and provide evidence for purinergic regulation of the protein translational pathways related to cell proliferation.
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Affiliation(s)
- Evgenia V Gerasimovskaya
- Developmental Lung Biology Laboratory, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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