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Caputo M, Ivanova D, Chasserot-Golaz S, Doussau F, Haeberlé AM, Royer C, Ozkan S, Ecard J, Vitale N, Cousin MA, Tóth P, Gasman S, Ory S. Phospholipid Scramblase 1 Controls Efficient Neurotransmission and Synaptic Vesicle Retrieval at Cerebellar Synapses. J Neurosci 2024; 44:e0042242024. [PMID: 38839301 PMCID: PMC11223464 DOI: 10.1523/jneurosci.0042-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 04/23/2024] [Accepted: 04/28/2024] [Indexed: 06/07/2024] Open
Abstract
Phospholipids (PLs) are asymmetrically distributed at the plasma membrane. This asymmetric lipid distribution is transiently altered during calcium-regulated exocytosis, but the impact of this transient remodeling on presynaptic function is currently unknown. As phospholipid scramblase 1 (PLSCR1) randomizes PL distribution between the two leaflets of the plasma membrane in response to calcium activation, we set out to determine its role in neurotransmission. We report here that PLSCR1 is expressed in cerebellar granule cells (GrCs) and that PLSCR1-dependent phosphatidylserine egress occurred at synapses in response to neuron stimulation. Synaptic transmission is impaired at GrC Plscr1 -/- synapses, and both PS egress and synaptic vesicle (SV) endocytosis are inhibited in Plscr1 -/- cultured neurons from male and female mice, demonstrating that PLSCR1 controls PL asymmetry remodeling and SV retrieval following neurotransmitter release. Altogether, our data reveal a novel key role for PLSCR1 in SV recycling and provide the first evidence that PL scrambling at the plasma membrane is a prerequisite for optimal presynaptic performance.
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Affiliation(s)
- Margherita Caputo
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Daniela Ivanova
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Sylvette Chasserot-Golaz
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Frédéric Doussau
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Anne-Marie Haeberlé
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Cathy Royer
- Plateforme Imagerie In Vitro, Centre National de la Recherche Scientifique UPS3256, Strasbourg F-67000, France
| | - Sebahat Ozkan
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Jason Ecard
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Petra Tóth
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
| | - Stéphane Ory
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg F-67000, France
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2
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Haase S, Condron M, Miller D, Cherkaoui D, Jordan S, Gulbis JM, Baum J. Identification and characterisation of a phospholipid scramblase in the malaria parasite Plasmodium falciparum. Mol Biochem Parasitol 2021; 243:111374. [PMID: 33974939 PMCID: PMC8202325 DOI: 10.1016/j.molbiopara.2021.111374] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/27/2021] [Accepted: 05/06/2021] [Indexed: 02/07/2023]
Abstract
Recent studies highlight the emerging role of lipids as important messengers in malaria parasite biology. In an attempt to identify interacting proteins and regulators of these dynamic and versatile molecules, we hypothesised the involvement of phospholipid translocases and their substrates in the infection of the host erythrocyte by the malaria parasite Plasmodium spp. Here, using a data base searching approach of the Plasmodium Genomics Resources (www.plasmodb.org), we have identified a putative phospholipid (PL) scramblase in P. falciparum (PfPLSCR) that is conserved across the genus and in closely related unicellular algae. By reconstituting recombinant PfPLSCR into liposomes, we demonstrate metal ion dependent PL translocase activity and substrate preference, confirming PfPLSCR as a bona fide scramblase. We show that PfPLSCR is expressed during asexual and sexual parasite development, localising to different membranous compartments of the parasite throughout the intra-erythrocytic life cycle. Two different gene knockout approaches, however, suggest that PfPLSCR is not essential for erythrocyte invasion and asexual parasite development, pointing towards a possible role in other stages of the parasite life cycle.
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Affiliation(s)
- Silvia Haase
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK.
| | - Melanie Condron
- Division of Infection and Immunity, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
| | - David Miller
- Division of Structural Biology, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
| | - Dounia Cherkaoui
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK
| | - Sarah Jordan
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK
| | - Jacqueline M Gulbis
- Division of Structural Biology, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jake Baum
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK.
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3
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Are cysteine residues of human phospholipid scramblase 1 essential for Pb 2+ and Hg 2+ binding-induced scrambling of phospholipids? EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:745-757. [PMID: 33787949 DOI: 10.1007/s00249-021-01521-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 03/06/2021] [Accepted: 03/20/2021] [Indexed: 10/21/2022]
Abstract
Lead and mercury being common environmental pollutants are often associated with erythrocytes, where phosphatidylserine (PS) exposure-mediated procoagulant activation is induced. Human phospholipid scramblase 1 (hPLSCR1) identified in the erythrocyte membrane is a type II transmembrane protein involved in Ca2+-dependent bidirectional scrambling of phospholipids (PL) during blood coagulation, cell activation, and apoptosis. The prominent role of hPLSCR1 in Pb2+ and Hg2+ poisoning was demonstrated by a biochemical assay, where recombinant hPLSCR1 induced PL scrambling across bilayer with a higher binding affinity (Kd) towards Hg2+ (4.1 µM) and Pb2+ (5.8 µM) than Ca2+ (25.6 mM). The increased affinity could be the outcome of heavy metals interacting at auxiliary sites other than the calcium-binding motif of hPLSCR1. Similar to other metal-binding proteins, cysteine-based metal-binding motifs could be the potential additional binding sites in hPLSCR1. To explore the hypothesis, the cysteines were chemically modified, which significantly reduced only the Hg2+- and Pb2+-induced scrambling activity leaving Ca2+-induced activity unaltered. Recombinant constructs with deletion of prominent cysteine residues and point mutation in the calcium-binding motif including Δ100-hPLSCR1, Δ160-hPLSCR1, and D275A-hPLSCR1 were generated, purified, and assayed for scramblase activity. The cysteine-deleted constructs of hPLSCR1 showed reduced binding affinity (Kd) for Hg2+ and Pb2+ without altering the Ca2+-binding affinity whereas the point mutant had completely lost its affinity for Ca2+ and reduced affinities for Hg2+ and Pb2+. The results accentuated the significance of cysteine residues as additional binding sites for heavy metal ions in hPLSCR1.
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4
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Bernhardt I, Nguyen DB, Wesseling MC, Kaestner L. Intracellular Ca 2+ Concentration and Phosphatidylserine Exposure in Healthy Human Erythrocytes in Dependence on in vivo Cell Age. Front Physiol 2020; 10:1629. [PMID: 31998145 PMCID: PMC6965055 DOI: 10.3389/fphys.2019.01629] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 12/24/2019] [Indexed: 12/24/2022] Open
Abstract
After about 120 days of circulation in the blood stream, erythrocytes are cleared by macrophages in the spleen and the liver. The “eat me” signal of this event is thought to be the translocation of phosphatidylserine from the inner to the outer membrane leaflet due to activation of the scramblase, while the flippase is inactivated. Both processes are triggered by an increased intracellular Ca2+ concentration. Although this is not the only mechanism involved in erythrocyte clearance, in this minireview, we focus on the following questions: Is the intracellular-free Ca2+ concentration and hence phosphatidylserine exposure dependent on the erythrocyte age, i.e. is the Ca2+ concentration, progressively raising during the erythrocyte aging in vivo? Can putative differences in intracellular Ca2+ and exposure of phosphatidylserine to the outer membrane leaflet be measured in age separated cell populations? Literature research revealed less than dozen of such publications with vastly contradicting results for the Ca2+ concentrations but consistency for a lack of change for the phosphatidylserine exposure. Additionally, we performed reanalysis of published data resulting in an ostensive illustration of the situation described above. Relating these results to erythrocyte physiology and biochemistry, we can conclude that the variation of the intracellular free Ca2+ concentration is limited with 10 μM as the upper level of the concentration. Furthermore, we propose the hypothesis that variations in measured Ca2+ concentrations may to a large extent depend on the experimental conditions applied but reflect a putatively changed Ca2+ susceptibility of erythrocytes in dependence of in vivo cell age.
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Affiliation(s)
- Ingolf Bernhardt
- Laboratory of Biophysics, Faculty of Natural Science and Technology, Saarland University, Saarbrücken, Germany
| | - Duc Bach Nguyen
- Laboratory of Biophysics, Faculty of Natural Science and Technology, Saarland University, Saarbrücken, Germany
| | - Mauro C Wesseling
- Laboratory of Biophysics, Faculty of Natural Science and Technology, Saarland University, Saarbrücken, Germany
| | - Lars Kaestner
- Experimental Physics, Faculty of Natural Science and Technology, Saarland University, Saarbrücken, Germany.,Theoretical Medicine and Biosciences, Medical Faculty, Saarland University, Homburg, Germany
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5
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Kaestner L, Bogdanova A, Egee S. Calcium Channels and Calcium-Regulated Channels in Human Red Blood Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:625-648. [PMID: 31646528 DOI: 10.1007/978-3-030-12457-1_25] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Free Calcium (Ca2+) is an important and universal signalling entity in all cells, red blood cells included. Although mature mammalian red blood cells are believed to not contain organelles as Ca2+ stores such as the endoplasmic reticulum or mitochondria, a 20,000-fold gradient based on a intracellular Ca2+ concentration of approximately 60 nM vs. an extracellular concentration of 1.2 mM makes Ca2+-permeable channels a major signalling tool of red blood cells. However, the internal Ca2+ concentration is tightly controlled, regulated and maintained primarily by the Ca2+ pumps PMCA1 and PMCA4. Within the last two decades it became evident that an increased intracellular Ca2+ is associated with red blood cell clearance in the spleen and promotes red blood cell aggregability and clot formation. In contrast to this rather uncontrolled deadly Ca2+ signals only recently it became evident, that a temporal increase in intracellular Ca2+ can also have positive effects such as the modulation of the red blood cells O2 binding properties or even be vital for brief transient cellular volume adaptation when passing constrictions like small capillaries or slits in the spleen. Here we give an overview of Ca2+ channels and Ca2+-regulated channels in red blood cells, namely the Gárdos channel, the non-selective voltage dependent cation channel, Piezo1, the NMDA receptor, VDAC, TRPC channels, CaV2.1, a Ca2+-inhibited channel novel to red blood cells and i.a. relate these channels to the molecular unknown sickle cell disease conductance Psickle. Particular attention is given to correlation of functional measurements with molecular entities as well as the physiological and pathophysiological function of these channels. This view is in constant progress and in particular the understanding of the interaction of several ion channels in a physiological context just started. This includes on the one hand channelopathies, where a mutation of the ion channel is the direct cause of the disease, like Hereditary Xerocytosis and the Gárdos Channelopathy. On the other hand it applies to red blood cell related diseases where an altered channel activity is a secondary effect like in sickle cell disease or thalassemia. Also these secondary effects should receive medical and pharmacologic attention because they can be crucial when it comes to the life-threatening symptoms of the disease.
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Affiliation(s)
- Lars Kaestner
- Theoretical Medicine and Biosciences, Saarland University, Homburg, Germany. .,Experimental Physics, Saarland University, Saarbrücken, Germany.
| | - Anna Bogdanova
- Red Blood Cell Research Group, Institute of Veterinary Physiology, Vetsuisse Faculty and the Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Stephane Egee
- CNRS, UMR8227 LBI2M, Sorbonne Université, Roscoff, France.,Laboratoire d'Excellence GR-Ex, Paris, France
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6
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Palanirajan SK, Gummadi SN. Rapid method for an enhanced recovery of biologically active human phospholipid scramblase1 from inclusion bodies. Anal Biochem 2018; 556:104-111. [DOI: 10.1016/j.ab.2018.06.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 06/28/2018] [Accepted: 06/28/2018] [Indexed: 01/05/2023]
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7
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Ahyayauch H, García-Arribas AB, Sot J, González-Ramírez EJ, Busto JV, Monasterio BG, Jiménez-Rojo N, Contreras FX, Rendón-Ramírez A, Martin C, Alonso A, Goñi FM. Pb(II) Induces Scramblase Activation and Ceramide-Domain Generation in Red Blood Cells. Sci Rep 2018; 8:7456. [PMID: 29748552 PMCID: PMC5945622 DOI: 10.1038/s41598-018-25905-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 04/19/2018] [Indexed: 01/01/2023] Open
Abstract
The mechanisms of Pb(II) toxicity have been studied in human red blood cells using confocal microscopy, immunolabeling, fluorescence-activated cell sorting and atomic force microscopy. The process follows a sequence of events, starting with calcium entry, followed by potassium release, morphological change, generation of ceramide, lipid flip-flop and finally cell lysis. Clotrimazole blocks potassium channels and the whole process is inhibited. Immunolabeling reveals the generation of ceramide-enriched domains linked to a cell morphological change, while the use of a neutral sphingomyelinase inhibitor greatly delays the process after the morphological change, and lipid flip-flop is significantly reduced. These facts point to three major checkpoints in the process: first the upstream exchange of calcium and potassium, then ceramide domain formation, and finally the downstream scramblase activation necessary for cell lysis. In addition, partial non-cytotoxic cholesterol depletion of red blood cells accelerates the process as the morphological change occurs faster. Cholesterol could have a role in modulating the properties of the ceramide-enriched domains. This work is relevant in the context of cell death, heavy metal toxicity and sphingolipid signaling.
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Affiliation(s)
- Hasna Ahyayauch
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Institut Supérieur des Professions Infirmières et des Techniques de Santé, Rabat, Morocco.,Neuroendocrinology Unit, Laboratory of Genetics, Neuroendocrinology and Biotechnology, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco
| | - Aritz B García-Arribas
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Jesús Sot
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain
| | - Emilio J González-Ramírez
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Jon V Busto
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Bingen G Monasterio
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Noemi Jiménez-Rojo
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain.,NCCR Chemical Biology, Department of Biochemistry, University of Geneva, 1211, Geneva, Switzerland
| | - F Xabier Contreras
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Adela Rendón-Ramírez
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Cesar Martin
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Alicia Alonso
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Félix M Goñi
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain. .,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain.
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8
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Interactions stabilizing the C-terminal helix of human phospholipid scramblase 1 in lipid bilayers: A computational study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1200-1210. [DOI: 10.1016/j.bbamem.2017.03.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 03/09/2017] [Accepted: 03/29/2017] [Indexed: 12/19/2022]
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9
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Andraka N, Sánchez-Magraner L, García-Pacios M, Goñi FM, Arrondo JLR. The conformation of human phospholipid scramblase 1, as studied by infrared spectroscopy. Effects of calcium and detergent. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1019-1028. [PMID: 28238818 DOI: 10.1016/j.bbamem.2017.02.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 02/18/2017] [Accepted: 02/22/2017] [Indexed: 12/18/2022]
Abstract
Human phospholipid scramblase 1 (SCR) is a membrane protein that catalyzes the transmembrane (flip-flop) motion of phospholipids. It can also exist in a non membrane-bound form in the nucleus, where it modulates several aspects of gene expression. Catalysis of phospholipid flip-flop requires the presence of millimolar Ca2+, and occurs in the absence of ATP. Membrane-bound SCR contains a C-terminal α-helical domain embedded in the membrane bilayer. The latter domain can be removed giving rise to a stable truncated mutant SCRΔ that is devoid of scramblase activity. In order to improve our understanding of SCR structure infrared spectra have been recorded of both the native and truncated forms, and the effects of adding Ca2+, or removing detergent, or thermally denaturing the protein have been observed. Under all conditions the main structural component of SCR/SCRΔ is a β-sheet. Removing the C-terminal 28 aa residues, which anchor SCR to the membrane, leads to a change in tertiary structure and an increased structural flexibility. The main effect of Ca2+ is an increase in the α/β ratio of secondary structure components, with a concomitant increase in the proportion of non-periodic structures. At least in SCRΔ, detergent (Zwittergent 3-12) decreases the structural flexibility, an effect somewhat opposite to that of increasing temperature. Thermal denaturation is affected by Ca2+, detergent, and by the presence or absence of the C-terminal domain, each of them influencing in different ways the denaturation pattern.
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Affiliation(s)
- Nagore Andraka
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain
| | - Lissete Sánchez-Magraner
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain
| | - Marcos García-Pacios
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain
| | - Félix M Goñi
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain
| | - José L R Arrondo
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain.
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10
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Gianolio E, Ferrauto G, Di Gregorio E, Aime S. Re-evaluation of the water exchange lifetime value across red blood cell membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:627-31. [PMID: 26744230 DOI: 10.1016/j.bbamem.2015.12.029] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 12/02/2015] [Accepted: 12/24/2015] [Indexed: 01/07/2023]
Abstract
The water exchange lifetime (τ(i)) through red blood cell (RBC) membranes can be measured by analyzing the water protons bi-exponential T1 and T2 curves when RBCs are suspended in a medium supplemented with paramagnetic species. Since the seminal papers published in the early '70s of the previous century, paramagnetic Mn(2+) ions were used for doping the extracellular compartment in the RBCs suspension. The obtained τ(i) values fall in the range of 9.8-14 ms. Conversely, other physic-chemical measurements afforded longer τ(i) values. Herein, it is shown that the replacement of Mn(2+) with the highly stable, hydrophilic Gd(III) complexes used as paramagnetic magnetic resonance imaging (MRI) contrast agents led to measure τ(iI) values of 19.1 ± 0.65 ms at 25 ° C. The observed difference is ascribed to the occurrence of enhanced permeability of RBC membrane in the presence of Mn(2+) ions. This view finds support from the observation that an analogous behavior was shown in the presence of other divalent cations, such Ca(2+) and Zn(2+) ions. A possible role of scramblase has been hypothesized. Finally, τ(i) has been measured in presence of alcohols to show that the herein proposed method can detect minor changes in RBC membranes' stiffness upon the incorporation of aliphatic alcohols.
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Affiliation(s)
- Eliana Gianolio
- University of Torino, Department of Molecular Biotechnologies and Health Science, Torino, Italy
| | - Giuseppe Ferrauto
- University of Torino, Department of Molecular Biotechnologies and Health Science, Torino, Italy
| | - Enza Di Gregorio
- University of Torino, Department of Molecular Biotechnologies and Health Science, Torino, Italy
| | - Silvio Aime
- University of Torino, Department of Molecular Biotechnologies and Health Science, Torino, Italy.
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11
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Francis VG, Gummadi SN. Biochemical evidence for Ca2+-independent functional activation of hPLSCR1 at low pH. ACTA ACUST UNITED AC 2015. [DOI: 10.1515/cmble-2015-0017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractHuman phospholipid scramblase 1 (hPLSCR1) is a Ca
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12
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Kassas A, Moura IC, Yamashita Y, Scheffel J, Guérin-Marchand C, Blank U, Sims PJ, Wiedmer T, Monteiro RC, Rivera J, Charles N, Benhamou M. Regulation of the tyrosine phosphorylation of Phospholipid Scramblase 1 in mast cells that are stimulated through the high-affinity IgE receptor. PLoS One 2014; 9:e109800. [PMID: 25289695 PMCID: PMC4188579 DOI: 10.1371/journal.pone.0109800] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 09/14/2014] [Indexed: 01/05/2023] Open
Abstract
Engagement of high-affinity immunoglobulin E receptors (FcεRI) activates two signaling pathways in mast cells. The Lyn pathway leads to recruitment of Syk and to calcium mobilization whereas the Fyn pathway leads to phosphatidylinositol 3-kinase recruitment. Mapping the connections between both pathways remains an important task to be completed. We previously reported that Phospholipid Scramblase 1 (PLSCR1) is phosphorylated on tyrosine after cross-linking FcεRI on RBL-2H3 rat mast cells, amplifies mast cell degranulation, and is associated with both Lyn and Syk tyrosine kinases. Here, analysis of the pathway leading to PLSCR1 tyrosine phosphorylation reveals that it depends on the FcRγ chain. FcεRI aggregation in Fyn-deficient mouse bone marrow-derived mast cells (BMMC) induced a more robust increase in FcεRI-dependent tyrosine phosphorylation of PLSCR1 compared to wild-type cells, whereas PLSCR1 phosphorylation was abolished in Lyn-deficient BMMC. Lyn association with PLSCR1 was not altered in Fyn-deficient BMMC. PLSCR1 phosphorylation was also dependent on the kinase Syk and significantly, but partially, dependent on detectable calcium mobilization. Thus, the Lyn/Syk/calcium axis promotes PLSCR1 phosphorylation in multiple ways. Conversely, the Fyn-dependent pathway negatively regulates it. This study reveals a complex regulation for PLSCR1 tyrosine phosphorylation in FcεRI-activated mast cells and that PLSCR1 sits at a crossroads between Lyn and Fyn pathways.
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Affiliation(s)
- Asma Kassas
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Ivan C. Moura
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Yumi Yamashita
- Laboratory of Molecular Immunogenetics, Molecular Immunology and Inflammation Branch, NIAMSD, NIH, Bethesda, Maryland, United States of America
| | - Jorg Scheffel
- Laboratory of Molecular Immunogenetics, Molecular Immunology and Inflammation Branch, NIAMSD, NIH, Bethesda, Maryland, United States of America
| | - Claudine Guérin-Marchand
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Ulrich Blank
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Peter J. Sims
- Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Therese Wiedmer
- Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Renato C. Monteiro
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Juan Rivera
- Laboratory of Molecular Immunogenetics, Molecular Immunology and Inflammation Branch, NIAMSD, NIH, Bethesda, Maryland, United States of America
| | - Nicolas Charles
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
- * E-mail: (NC); (MB)
| | - Marc Benhamou
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
- * E-mail: (NC); (MB)
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13
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Slone EA, Fleming SD. Membrane lipid interactions in intestinal ischemia/reperfusion-induced Injury. Clin Immunol 2014; 153:228-40. [PMID: 24814240 DOI: 10.1016/j.clim.2014.04.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 04/10/2014] [Accepted: 04/29/2014] [Indexed: 01/02/2023]
Abstract
Ischemia, lack of blood flow, and reperfusion, return of blood flow, are a common phenomenon affecting millions of Americans each year. Roughly 30,000 Americans per year experience intestinal ischemia-reperfusion (IR), which is associated with a high mortality rate. Previous studies of the intestine established a role for neutrophils, eicosanoids, the complement system and naturally occurring antibodies in IR-induced pathology. Furthermore, data indicate involvement of a lipid or lipid-like moiety in mediating IR-induced damage. It has been proposed that antibodies recognize exposure of neo-antigens, triggering action of the complement cascade. While it is evident that the pathophysiology of IR-induced injury is complex and multi-factorial, we focus this review on the involvement of eicosanoids, phospholipids and neo-antigens in the early pathogenesis. Lipid changes occurring in response to IR, neo-antigens exposed and the role of a phospholipid transporter, phospholipid scramblase 1 will be discussed.
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Affiliation(s)
- Emily Archer Slone
- College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
| | - Sherry D Fleming
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
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14
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Membrane binding of human phospholipid scramblase 1 cytoplasmic domain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1785-92. [PMID: 24680654 DOI: 10.1016/j.bbamem.2014.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 03/12/2014] [Accepted: 03/18/2014] [Indexed: 02/08/2023]
Abstract
Human phospholipid scramblase 1 (SCR) consists of a large cytoplasmic domain and a small presumed transmembrane domain near the C-terminal end of the protein. Previous studies with the SCRΔ mutant lacking the C-terminal portion (last 28 aa) revealed the importance of this C-terminal moiety for protein function and calcium-binding affinity. The present contribution is intended to elucidate the effect of the transmembrane domain suppression on SCRΔ binding to model membranes (lipid monolayers and bilayers) and on SCRΔ reconstitution in proteoliposomes. In all cases the protein cytoplasmic domain showed a great affinity for lipid membranes, and behaved in most aspects as an intrinsic membrane protein. Assays have been performed in the presence of phosphatidylserine, presumably important for the SCR cytoplasmic domain to be electrostatically anchored to the plasma membrane inner surface. The fusion protein maltose binding protein-SCR has also been studied as an intermediate case of a molecule that can insert into the bilayer hydrophobic core, yet it is stable in detergent-free buffers. Although the intracellular location of SCR has been the object of debate, the present data support the view of SCR as an integral membrane protein, in which not only the transmembrane domain but also the cytoplasmic moiety play a role in membrane docking of the protein.
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15
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Rayala S, Francis VG, Sivagnanam U, Gummadi SN. N-terminal proline-rich domain is required for scrambling activity of human phospholipid scramblases. J Biol Chem 2014; 289:13206-18. [PMID: 24648509 DOI: 10.1074/jbc.m113.522953] [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] [Indexed: 01/19/2023] Open
Abstract
Human phospholipid scramblase 1 (hPLSCR1), a type II integral class membrane protein, is known to mediate bidirectional scrambling of phospholipids in a Ca(2+)-dependent manner. hPLSCR2, a homolog of hPLSCR1 that lacks N-terminal proline-rich domain (PRD), did not show scramblase activity. We attribute this absence of scramblase activity of hPLSCR2 to the lack of N-terminal PRD. Hence to investigate the above hypothesis, we added the PRD of hPLSCR1 to hPLSCR2 (PRD-hPLSCR2) and checked whether scramblase activity was restored. Functional assays showed that the addition of PRD to hPLSCR2 restored scrambling activity, and deletion of PRD in hPLSCR1 (ΔPRD-hPLSCR1) resulted in a lack of activity. These results suggest that PRD is crucial for the function of the protein. The effects of the PRD deletion in hPLSCR1 and the addition of PRD to hPLSCR2 were characterized using various spectroscopic techniques. Our results clearly showed that hPLSCR1 and PRD-hPLSCR2 showed Ca(2+)-dependent aggregation and scrambling activity, whereas hPLSCR2 and ΔPRD-hPLSCR1 did not show aggregation and activity. Thus we conclude that scramblases exhibit Ca(2+)-dependent scrambling activity by aggregation of protein. Our results provide a possible mechanism for phospholipid scrambling mediated by PLSCRs and the importance of PRD in its function and cellular localization.
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Affiliation(s)
- Sarika Rayala
- From the Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India
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16
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The C-terminal transmembrane domain of human phospholipid scramblase 1 is essential for the protein flip-flop activity and Ca²⁺-binding. J Membr Biol 2013; 247:155-65. [PMID: 24343571 DOI: 10.1007/s00232-013-9619-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 11/26/2013] [Indexed: 10/25/2022]
Abstract
Human phospholipid scramblase 1 (SCR) is a 318 amino acid protein that was originally described as catalyzing phospholipid transbilayer (flip-flop) motion in plasma membranes in a Ca²⁺-dependent, ATP-independent way. Further studies have suggested an intranuclear role for this protein in addition. A putative transmembrane domain located at the C terminus (aa 291-309) has been related to the flip-flop catalysis. In order to clarify the role of the C-terminal region of SCR, a mutant was produced (SCRΔ) in which the last 28 amino acid residues were lacking, including the α-helix. SCRΔ had lost the scramblase activity and its affinity for Ca²⁺ was decreased by one order of magnitude. Fluorescence and IR spectroscopic studies revealed that the C-terminal region of SCR was essential for the proper folding of the protein. Moreover, it was found that Ca²⁺ exerted an overall destabilizing effect on SCR, which might facilitate its binding to membranes.
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17
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Francis VG, Mohammed AM, Aradhyam GK, Gummadi SN. The single C-terminal helix of human phospholipid scramblase 1 is required for membrane insertion and scrambling activity. FEBS J 2013; 280:2855-69. [PMID: 23590222 DOI: 10.1111/febs.12289] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 03/12/2013] [Accepted: 04/15/2013] [Indexed: 11/29/2022]
Abstract
Human phospholipid scramblase 1 (hPLSCR1) belongs to the ATP-independent class of phospholipid translocators which possess a single EF-hand-like Ca(2+)-binding motif and also a C-terminal helix (CTH). The CTH domain of hPLSCR1 was believed to be a putative single transmembrane helix at the C-terminus. Recent homology modeling studies by Bateman et al. predicted that the hydrophobic nature of this helix is due to its packing in the core of the protein domain and proposed that this is not a true transmembrane helix [Bateman A, Finn RD, Sims PJ, Wiedmer T, Biegert A & Johannes S. Bioinformatics 2008, 25, 159]. To determine the exact function of the CTH of hPLSCR1, we deleted the CTH domain and determined: (a) whether CTH plays any role beyond membrane anchorage, (b) the functional consequences of CTH deletion, and (c) any conformational changes associated with CTH in a lipid environment. In vitro reconstitution studies confirm that the predicted CTH is required for membrane insertion and scrambling activity. CTH deletion caused a 50% decrease in binding affinity of Ca(2+) for ∆CTH-hPLSCR1 (K(a) = 115 μM) compared with hPLSCR1 (K(a) = 249 μM). Far UV-CD studies revealed that the CTH peptide adopts α-helicity only in the presence of SDS micelles and negatively charged vesicles, indicating that electrostatic interactions are required for insertion of the peptide. CTH peptide-quenching studies confirm that the predicted CTH inserts into the membrane and its ability to interact with the membrane depends on the presence of charge interactions. TOXCAT assay revealed that CTH of hPLSCR1 does not oligomerize in the membrane. We conclude that CTH is required for membrane insertion and Ca(2+) coordination and also plays an important role in the functional conformation of hPLSCR1.
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Affiliation(s)
- Vincent G Francis
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India
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18
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Shettihalli AK, Gummadi SN. Biochemical evidence for lead and mercury induced transbilayer movement of phospholipids mediated by human phospholipid scramblase 1. Chem Res Toxicol 2013; 26:918-25. [PMID: 23659204 DOI: 10.1021/tx400090h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Human phospholipid scramblase 1(hPLSCR1) is a transmembrane protein involved in bidirectional scrambling of plasma membrane phospholipids during cell activation, blood coagulation, and apoptosis in response to elevated intracellular Ca(2+) levels. Pb(2+) and Hg(2+) are known to cause procoagulant activation via phosphatidylserine exposure to the external surface in erythrocytes, resulting in blood coagulation. To explore its role in lead and mercury poisoning, hPLSCR1 was overexpressed in Escherichia coli BL21 (DE3) and purified using affinity chromatography. The biochemical assay showed rapid scrambling of phospholipids in the presence of Hg(2+) and Pb(2+). The binding constant (Ka) was calculated and found to be 250 nM(-1) and 170 nM(-1) for Hg(2+) and Pb(2+), respectively. The intrinsic tryptophan fluorescence and far ultraviolet circular dichroism studies revealed that Hg(2+) and Pb(2+) bind to hPLSCR1 and induce conformational changes. hPLSCR1 treated with protein modifying reagent N-ethylmaleimide before functional reconstitution showed 40% and 24% inhibition in the presence of Hg(2+) and Pb(2+), respectively. This is the first biochemical evidence to prove the above hypothesis that hPLSCR1 is activated in heavy metal poisoning, which leads to bidirectional transbilayer movement of phospholipids.
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Affiliation(s)
- Ashok Kumar Shettihalli
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India
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19
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Bogdanova A, Makhro A, Wang J, Lipp P, Kaestner L. Calcium in red blood cells-a perilous balance. Int J Mol Sci 2013; 14:9848-72. [PMID: 23698771 PMCID: PMC3676817 DOI: 10.3390/ijms14059848] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 03/18/2013] [Accepted: 03/19/2013] [Indexed: 12/19/2022] Open
Abstract
Ca2+ is a universal signalling molecule involved in regulating cell cycle and fate, metabolism and structural integrity, motility and volume. Like other cells, red blood cells (RBCs) rely on Ca2+ dependent signalling during differentiation from precursor cells. Intracellular Ca2+ levels in the circulating human RBCs take part not only in controlling biophysical properties such as membrane composition, volume and rheological properties, but also physiological parameters such as metabolic activity, redox state and cell clearance. Extremely low basal permeability of the human RBC membrane to Ca2+ and a powerful Ca2+ pump maintains intracellular free Ca2+ levels between 30 and 60 nM, whereas blood plasma Ca2+ is approximately 1.8 mM. Thus, activation of Ca2+ uptake has an impressive impact on multiple processes in the cells rendering Ca2+ a master regulator in RBCs. Malfunction of Ca2+ transporters in human RBCs leads to excessive accumulation of Ca2+ within the cells. This is associated with a number of pathological states including sickle cell disease, thalassemia, phosphofructokinase deficiency and other forms of hereditary anaemia. Continuous progress in unravelling the molecular nature of Ca2+ transport pathways allows harnessing Ca2+ uptake, avoiding premature RBC clearance and thrombotic complications. This review summarizes our current knowledge of Ca2+ signalling in RBCs emphasizing the importance of this inorganic cation in RBC function and survival.
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Affiliation(s)
- Anna Bogdanova
- Institute of Veterinary Physiology, Vetsuisse Faculty and the Zürich, Center for Integrative Human Physiology, University of Zürich, Zürich 8057, Switzerland; E-Mails: (A.B.); (A.M.)
| | - Asya Makhro
- Institute of Veterinary Physiology, Vetsuisse Faculty and the Zürich, Center for Integrative Human Physiology, University of Zürich, Zürich 8057, Switzerland; E-Mails: (A.B.); (A.M.)
| | - Jue Wang
- Institute for Molecular Cell Biology and Research Centre for Molecular Imaging and Screening, Saarland University, Homburg/Saar 66421, Germany; E-Mails: (J.W.); (P.L.)
| | - Peter Lipp
- Institute for Molecular Cell Biology and Research Centre for Molecular Imaging and Screening, Saarland University, Homburg/Saar 66421, Germany; E-Mails: (J.W.); (P.L.)
| | - Lars Kaestner
- Institute for Molecular Cell Biology and Research Centre for Molecular Imaging and Screening, Saarland University, Homburg/Saar 66421, Germany; E-Mails: (J.W.); (P.L.)
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20
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Phospholipid scramblase-1-induced lipid reorganization regulates compensatory endocytosis in neuroendocrine cells. J Neurosci 2013; 33:3545-56. [PMID: 23426682 DOI: 10.1523/jneurosci.3654-12.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Calcium-regulated exocytosis in neuroendocrine cells and neurons is accompanied by the redistribution of phosphatidylserine (PS) to the extracellular space, leading to a disruption of plasma membrane asymmetry. How and why outward translocation of PS occurs during secretion are currently unknown. Immunogold labeling on plasma membrane sheets coupled with hierarchical clustering analysis demonstrate that PS translocation occurs at the vicinity of the secretory granule fusion sites. We found that altering the function of the phospholipid scramblase-1 (PLSCR-1) by expressing a PLSCR-1 calcium-insensitive mutant or by using chromaffin cells from PLSCR-1⁻/⁻ mice prevents outward translocation of PS in cells stimulated for exocytosis. Remarkably, whereas transmitter release was not affected, secretory granule membrane recapture after exocytosis was impaired, indicating that PLSCR-1 is required for compensatory endocytosis but not for exocytosis. Our results provide the first evidence for a role of specific lipid reorganization and calcium-dependent PLSCR-1 activity in neuroendocrine compensatory endocytosis.
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21
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Francis VG, Majeed MA, Gummadi SN. Recovery of functionally active recombinant human phospholipid scramblase 1 from inclusion bodies using N-lauroyl sarcosine. J Ind Microbiol Biotechnol 2012; 39:1041-8. [PMID: 22389205 DOI: 10.1007/s10295-012-1105-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Accepted: 02/07/2012] [Indexed: 12/18/2022]
Abstract
Human phospholipid scramblase (hPLSCR1) is a transmembrane protein involved in rapid bidirectional scrambling of phospholipids across the plasma membrane in response to elevated intracellular calcium (Ca(2+)) levels. Overexpression of recombinant hPLSCR1 in Escherichia coli BL21 (DE3) leads to its deposition in inclusion bodies (IBs). N-lauroyl sarcosine was used to solubilize IBs and to recover functionally active hPLSCR1 from them. Protein was purified to homogeneity by nickel-nitrilotriacetic acid (Ni(2+)-NTA) affinity chromatography and was >98% pure. Functional activity of the purified protein was validated by in vitro reconstitution studies, ~18% of 7-nitrobenz-2-oxa-1, 3-diazol-4-yl-phosphatidylcholine (NBD-PC) phospholipids was translocated across the lipid bilayer in the presence of Ca(2+) ions. Far ultraviolet circular dichroism (UV-CD) studies reveal that the secondary structure of protein is predominantly an α-helix, and under nondenaturing conditions, the protein exists as a monomer. Here we describe a method to purify recombinant membrane protein with higher yield than previously described methods involving renaturation techniques.
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Affiliation(s)
- Vincent Gerard Francis
- Applied Industrial Microbiology Laboratory, Department of Biotechnology, Indian Institute of Technology-Madras, Chennai, 600036, India
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22
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Weiss E, Cytlak UM, Rees DC, Osei A, Gibson JS. Deoxygenation-induced and Ca(2+) dependent phosphatidylserine externalisation in red blood cells from normal individuals and sickle cell patients. Cell Calcium 2011; 51:51-6. [PMID: 22197026 DOI: 10.1016/j.ceca.2011.10.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 09/29/2011] [Accepted: 10/23/2011] [Indexed: 01/03/2023]
Abstract
Phosphatidylserine (PS) is usually confined to the inner leaflet of the red blood cell (RBC) membrane. It may become externalised in various conditions, however, notably in RBCs from patients with sickle cell disease (SCD) where exposed PS may contribute to anaemic and ischaemic complications. PS externalisation requires both inhibition of the aminophospholipid translocase (or flippase) and activation of the scramblase. Both may follow from elevation of intracellular Ca(2+). Flippase inhibition occurs at low [Ca(2+)](i), about 1μM, but [Ca(2+)](i) required for scrambling is reported to be much higher (around 100μM). In this work, FITC-labelled lactadherin and FACS were used to measure externalised PS, with [Ca(2+)](i) altered using bromo-A23187 and EGTA/Ca(2+) mixtures. Two components of Ca(2+)-induced scrambling were apparent, of high (EC(50) 1.8±0.3μM) and low (306±123μM) affinity, in RBCs from normal individuals and the commonest SCD genotypes, HbSS and HbSC. The high affinity component was lost in the presence of unphysiologically high [Mg(2+)] but was unaffected by high K(+) (90mM) or vanadate (1mM). The high affinity component accounted for PS scrambling in ≥2/3rd RBCs. It is likely to be most significant in vivo and may be involved in the pathophysiology of SCD or other conditions involving eryptosis.
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Affiliation(s)
- Erwin Weiss
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
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23
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Steffen P, Jung A, Nguyen DB, Müller T, Bernhardt I, Kaestner L, Wagner C. Stimulation of human red blood cells leads to Ca2+-mediated intercellular adhesion. Cell Calcium 2011; 50:54-61. [PMID: 21616535 DOI: 10.1016/j.ceca.2011.05.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 04/30/2011] [Accepted: 05/03/2011] [Indexed: 10/24/2022]
Abstract
Red blood cells (RBCs) are a major component of blood clots, which form physiologically as a response to injury or pathologically in thrombosis. The active participation of RBCs in thrombus solidification has been previously proposed but not yet experimentally proven. Holographic optical tweezers and single-cell force spectroscopy were used to study potential cell-cell adhesion between RBCs. Irreversible intercellular adhesion of RBCs could be induced by stimulation with lysophosphatidic acid (LPA), a compound known to be released by activated platelets. We identified Ca(2+) as an essential player in the signaling cascade by directly inducing Ca(2+) influx using A23187. Elevation of the internal Ca(2+) concentration leads to an intercellular adhesion of RBCs similar to that induced by LPA stimulation. Using single-cell force spectroscopy, the adhesion of the RBCs was identified to be approximately 100 pN, a value large enough to be of significance inside a blood clot or in pathological situations like the vasco-occlusive crisis in sickle cell disease patients.
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Affiliation(s)
- Patrick Steffen
- Experimental Physics Department, Saarland University, 66123 Saarbruecken, Germany
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24
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Chen CW, Sowden M, Zhao Q, Wiedmer T, Sims PJ. Nuclear phospholipid scramblase 1 prolongs the mitotic expansion of granulocyte precursors during G-CSF-induced granulopoiesis. J Leukoc Biol 2011; 90:221-33. [PMID: 21447647 DOI: 10.1189/jlb.0111006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PLSCR1-/- mice exhibit normal, steady-state hematologic parameters but impaired emergency granulopoiesis upon in vivo administration of G-CSF. The mechanism by which PLSCR1 contributes to G-CSF-induced neutrophil production is largely unknown. We now report that the expansion of bone marrow myelocytes upon in vivo G-CSF treatment is reduced in PLSCR1-/- mice relative to WT. Using SCF-ER-Hoxb8-immortalized myeloid progenitors to examine the progression of G-CSF-driven granulocytic differentiation in vitro, we found that PLSCR1 prolongs the period of mitotic expansion of proliferative granulocyte precursors, thereby giving rise to increased neutrophil production from their progenitors. This effect of PLSCR1 is blocked by a ΔNLS-PLSCR1, which prevents its nuclear import. By contrast, mutation that prevents the membrane association of PLSCR1 has minimal impact on the role of PLSCR1 in G-CSF-induced granulopoiesis. These data imply that the capacity of PLSCR1 to augment G-CSF-dependent production of mature neutrophils from myeloid progenitors is unrelated to its reported activities at the endofacial surface of the plasma membrane but does require entry of the protein into the nucleus, suggesting that this response is mediated through the observed effects of PLSCR1 on gene transcription.
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Affiliation(s)
- Chun-Wei Chen
- Department of Pathology and Laboratory Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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25
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Role of calcium in phosphatidylserine externalisation in red blood cells from sickle cell patients. Anemia 2010; 2011:379894. [PMID: 21490763 PMCID: PMC3065920 DOI: 10.1155/2011/379894] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 08/23/2010] [Indexed: 01/15/2023] Open
Abstract
Phosphatidylserine exposure occurs in red blood cells (RBCs) from sickle cell disease (SCD) patients and is increased by deoxygenation. The mechanisms responsible remain unclear. RBCs from SCD patients also have elevated cation permeability, and, in particular, a deoxygenation-induced cation conductance which mediates Ca2+ entry, providing an obvious link with phosphatidylserine exposure. The role of Ca2+ was investigated using FITC-labelled annexin. Results confirmed high phosphatidylserine exposure in RBCs from SCD patients increasing upon deoxygenation. When deoxygenated, phosphatidylserine exposure was further elevated as extracellular [Ca2+] was increased. This effect was inhibited by dipyridamole, intracellular Ca2+ chelation, and Gardos channel inhibition. Phosphatidylserine exposure was reduced in high K+ saline. Ca2+ levels required to elicit phosphatidylserine exposure were in the low micromolar range. Findings are consistent with Ca2+ entry through the deoxygenation-induced pathway (Psickle), activating the Gardos channel. [Ca2+] required for phosphatidylserine scrambling are in the range achievable in vivo.
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26
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Transbilayer (flip-flop
) lipid motion and lipid scrambling in membranes. FEBS Lett 2009; 584:1779-86. [DOI: 10.1016/j.febslet.2009.12.049] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 12/18/2009] [Indexed: 12/24/2022]
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27
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Sahu SK, Aradhyam GK, Gummadi SN. Calcium binding studies of peptides of human phospholipid scramblases 1 to 4 suggest that scramblases are new class of calcium binding proteins in the cell. Biochim Biophys Acta Gen Subj 2009; 1790:1274-81. [PMID: 19540310 DOI: 10.1016/j.bbagen.2009.06.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 06/04/2009] [Accepted: 06/14/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND Phospholipid scramblases are a group of four homologous proteins conserved from C. elegans to human. In human, two members of the scramblase family, hPLSCR1 and hPLSCR3 are known to bring about Ca2+ dependent translocation of phosphatidylserine and cardiolipin respectively during apoptotic processes. However, affinities of Ca2+/Mg2+ binding to human scramblases and conformational changes taking place in them remains unknown. METHODS In the present study, we analyzed the Ca2+ and Mg2+ binding to the calcium binding motifs of hPLSCR1-4 and hPLSCR1 by spectroscopic methods and isothermal titration calorimetry. RESULTS The results in this study show that (i) affinities of the peptides are in the order hPLSCR1>hPLSCR3>hPLSCR2>hPLSCR4 for Ca2+ and in the order hPLSCR1>hPLSCR2>hPLSCR3>hPLSCR4 for Mg2+, (ii) binding of ions brings about conformational change in the secondary structure of the peptides. The affinity of Ca2+ and Mg2+ binding to protein hPLSCR1 was similar to that of the peptide I. A sequence comparison shows the existence of scramblase-like motifs among other protein families. CONCLUSIONS Based on the above results, we hypothesize that the Ca2+ binding motif of hPLSCR1 is a novel type of Ca2+ binding motif. GENERAL SIGNIFICANCE Our findings will be relevant in understanding the calcium dependent scrambling activity of hPLSCRs and their biological function.
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Affiliation(s)
- Santosh Kumar Sahu
- Department of Biotechnology, Indian Institute of Technology--Madras, Chennai 600 036, India
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Philominathan STL, Matsushita O, Gensure R, Sakon J. Ca2+-induced linker transformation leads to a compact and rigid collagen-binding domain of Clostridium histolyticum collagenase. FEBS J 2009; 276:3589-601. [PMID: 19490118 DOI: 10.1111/j.1742-4658.2009.07078.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Clostridium histolyticum collagenase is responsible for extensive tissue destruction in gas gangrene, and its activity is enhanced by calcium ions. The collagen-binding domain is the minimal segment of the enzyme required for binding to insoluble collagen fibrils and for subsequent collagenolysis. The collagen-binding domain is joined to another binding module by a conserved 14-amino-acid linker. The linker undergoes secondary structural transformation from an alpha-helix to a beta-strand and forms a nonprolyl cis-peptide in the presence of calcium ions. In this study, various biophysical methods were utilized to better understand the structure and functional role of the novel calcium-activated linker. Two Ca(2+) ions bind cooperatively with macroscopic association constants of K(1) = 5.01 x 10(5) m(-1) and K(2) = 2.28 x 10(5) m(-1). The chelation of the second calcium ion is enthalpically unfavorable, which could be a result of isomerization of the nonprolyl cis-peptide. The holo protein is more stable than the apo protein against thermal denaturation (DeltaT(m) approximately 20 degrees C) and chemical denaturation (DeltaDeltaG(H2O) approximately 3 kcal x mol(-1) for urea or guanidine HCl denaturation and Delta20% v/v in 2,2,2-trifluoroethanol). The compact holo collagen-binding domain is more resistant to proteolytic digestion than the apo collagen-binding domain. The orientation of the linker appears to play a crucial role in the stability and dynamics of the collagen-binding domain.
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Sahu SK, Gopala Krishna A, Gummadi SN. Over-expression of recombinant human phospholipid scramblase 1 in E. coli and its purification from inclusion bodies. Biotechnol Lett 2008; 30:2131-7. [DOI: 10.1007/s10529-008-9797-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 07/01/2008] [Accepted: 07/01/2008] [Indexed: 10/21/2022]
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Smrz D, Lebduska P, Dráberová L, Korb J, Dráber P. Engagement of phospholipid scramblase 1 in activated cells: implication for phosphatidylserine externalization and exocytosis. J Biol Chem 2008; 283:10904-18. [PMID: 18281686 DOI: 10.1074/jbc.m710386200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Phosphatidylserine (PS) in quiescent cells is predominantly confined to the inner leaflet of the plasma membrane. Externalization of PS is a marker of apoptosis, exocytosis, and some nonapoptotic activation events. It has been proposed that PS externalization is regulated by the activity of PLSCR1 (phospholipid scramblase 1), a Ca(2+)-dependent endofacial plasma membrane protein, which is tyrosine-phosphorylated in activated cells. It is, however, unclear how the phosphorylation of PLSCR1 is related to its membrane topography, PS externalization, and exocytosis. Using rat basophilic leukemia cells as a model, we show that nonapoptotic PS externalization induced through the high affinity IgE receptor (FcepsilonRI) or the glycosylphosphatidylinositol-anchored protein Thy-1 does not correlate with enhanced tyrosine phosphorylation of PLSCR1. In addition, PS externalization in FcepsilonRI- or Thy-1-activated cells is not associated with alterations of PLSCR1 fine topography as detected by electron microscopy on isolated plasma membrane sheets. In contrast, activation by calcium ionophore A23187 induces changes in the cellular distribution of PLSCR1. We also show for the first time that in pervanadate-activated cells, exocytosis occurs even in the absence of PS externalization. Finally, we document here that tyrosine-phosphorylated PLSCR1 is preferentially located in detergent-insoluble membranes, suggesting its involvement in the formation of membrane-bound signaling assemblies. The combined data indicate that changes in the topography of PLSCR1 and its tyrosine phosphorylation, PS externalization, and exocytosis are independent phenomena that could be distinguished by employing specific conditions of activation.
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Affiliation(s)
- Daniel Smrz
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, CZ 14220 Prague 4, Czech Republic
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31
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Sahu SK, Gummadi SN, Manoj N, Aradhyam GK. Phospholipid scramblases: An overview. Arch Biochem Biophys 2007; 462:103-14. [PMID: 17481571 DOI: 10.1016/j.abb.2007.04.002] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2007] [Revised: 03/30/2007] [Accepted: 04/01/2007] [Indexed: 12/23/2022]
Abstract
Phospholipid scramblases are a group of homologous proteins that are conserved in all eukaryotic organisms. They are believed to be involved in destroying plasma membrane phospholipid asymmetry at critical cellular events like cell activation, injury and apoptosis. However, a detailed mechanism of phospholipid scrambling still awaits a proper understanding. The most studied member of this family, phospholipid scramblase 1 (PLSCR1) (a 37kDa protein), is involved in rapid Ca2+ dependent transbilayer redistribution of plasma membrane phospholipids. Recently the function of PLSCR1 as a phospholipids translocator has been challenged and evidences suggest that PLSCR1 acts as signaling molecule. It has been shown to be involved in protein phosphorylation and as a potential activator of genes in response to interferon and other cytokines. Interferon induced rapid biosynthesis of PLSCR1 targets some of the protein into the nucleus, where it binds to the promoter region of inositol 1,4,5-triphosphate (IP3) receptor type 1 (IP3R1) gene and induces its expression. Palmitoylation of PLSCR1 acts as a switch, controlling its localization either to the PM or inside the nucleus. In the present review, we discuss the current understanding of PLSCR1 in relation to its trafficking, localization and signaling functions.
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Affiliation(s)
- Santosh Kumar Sahu
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India
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32
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Weathers EA, Paulaitis ME, Woolf TB, Hoh JH. Insights into protein structure and function from disorder-complexity space. Proteins 2007; 66:16-28. [PMID: 17044059 DOI: 10.1002/prot.21055] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Intrinsically disordered proteins have a wide variety of important functional roles. However, the relationship between sequence and function in these proteins is significantly different than that for well-folded proteins. In a previous work, we showed that the propensity to be disordered can be recognized based on sequence composition alone. Here that analysis is furthered by examining the relationship of disorder propensity to sequence complexity, where the metrics for these two properties depend only on composition. The distributions of 40 amino acid peptides from both ordered and disordered proteins are graphed in this disorder-complexity space. An analysis of Swiss-Prot shows that most peptides have high complexity and relatively low disorder. However, there are also an appreciable number of low complexity-high disorder peptides in the database. In contrast, there are no low complexity-low disorder peptides. A similar analysis for peptides in the PDB reveals a much narrower distribution, with few peptides of low complexity and high disorder. In this case, the bounds of the disorder-complexity distribution are well defined and might be used to evaluate the likelihood that a peptide can be crystallized with current methods. The disorder-complexity distributions of individual proteins and sets of proteins grouped by function are also examined. Among individual proteins, there is an enormous variety of distributions that in some cases can be rationalized with regard to function. Groups of functionally related proteins are found to have distributions that are similar within each group but show notable differences between groups. Finally, a pattern matching algorithm is used to search for proteins with particular disorder-complexity distributions. The results suggest that this approach might be used to identify relationships between otherwise dissimilar proteins.
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Affiliation(s)
- Edward A Weathers
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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33
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Influence of metal ions on phosphatidylcholine–bovine serum albumin model membrane, an FTIR study. J Mol Struct 2006. [DOI: 10.1016/j.molstruc.2006.01.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Increased oxidant stress has been suggested to play a role in the process of phosphatidylserine (PS) externalization in the red blood cells of sickle cell patients. Inhibition of the ATP-driven translocation from outer to inner monolayer (flippase) by sulphydryl modification has been established. The present study showed that phospholipid scrambling was also sensitive to protein sulphydryl modification. Treatment with N-ethylmaleimide lead to enhanced PS exposure and a lower Ca(++) requirement for scrambling. In contrast, pyridyldithioethylamine treatment inhibited PS exposure. Red blood cells from a murine model for sickle cell disease exhibited a reduced response to both reagents, suggestive of previous sulphydryl modifications to the protein(s) involved in phospholipid scrambling. We conclude that sulphydryl modifications to both scramblase and flippase underlie the enhanced formation of PS-exposing cells in sickle cell disease.
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Affiliation(s)
- Kitty de Jong
- Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA.
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35
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Ghosh P, Moitra K, Maki N, Dey S. Allosteric modulation of the human P-glycoprotein involves conformational changes mimicking catalytic transition intermediates. Arch Biochem Biophys 2006; 450:100-12. [PMID: 16624245 DOI: 10.1016/j.abb.2006.02.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 02/21/2006] [Accepted: 02/23/2006] [Indexed: 10/24/2022]
Abstract
The drug transport function of human P-glycoprotein (Pgp, ABCB1) can be inhibited by a number of pharmacological agents collectively referred to as modulators or reversing agents. In this study, we demonstrate that certain thioxanthene-based Pgp modulators with an allosteric mode of action induce a distinct conformational change in the cytosolic domain of Pgp, which alters susceptibility to proteolytic digestion. Both cis and trans-isomers of the Pgp modulator flupentixol confer considerable protection of an 80 kDa Pgp fragment against trypsin digestion, that is recognized by a polyclonal antibody specific for the NH(2)-terminal half to Pgp. The protection by flupentixol is abolished in the Pgp F983A mutant that is impaired in modulation by flupentixols, indicating involvement of the allosteric site in generating the conformational change. A similar protection to an 80 kDa fragment is conferred by ATP, its nonhydrolyzable analog ATPgammaS, and by trapping of ADP-vanadate at the catalytic domain, but not by transport substrate vinblastine or by the competitive modulator cyclosporin A, suggesting different outcomes from modulator interaction at the allosteric site and at the substrate site. In summary, we demonstrate that allosteric interaction of flupentixols with Pgp generates conformational changes that mimic catalytic transition intermediates induced by nucleotide binding and hydrolysis, which may play a crucial role in allosteric inhibition of Pgp-mediated drug transport.
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Affiliation(s)
- Pratiti Ghosh
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, F. Edward Hébert School of Medicine, 4301 Jones Bridge Road, Bethesda, MD 20814-4799, USA
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36
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Dias AV, Zamble DB. Protease digestion analysis of Escherichia coli NikR: evidence for conformational stabilization with Ni(II). J Biol Inorg Chem 2005; 10:605-12. [PMID: 16133200 DOI: 10.1007/s00775-005-0008-2] [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] [Received: 05/25/2005] [Accepted: 07/07/2005] [Indexed: 10/25/2022]
Abstract
The Escherichia coli NikR is a 15-kDa protein that negatively regulates transcription of the nikABCDE operon that encodes for an ATP-dependent Ni(II) permease. Thermal and chemical denaturation studies with NikR previously demonstrated that Ni(II)-NikR is more stable than the protein bound to other metals such as Cu(II), Co(II) and Zn(II). To determine if Ni(II) induces a unique conformational change in NikR, digestion experiments with selected proteases were performed in the presence of the above metals. Both denaturing-polyacrylamide gel electrophoresis and reversed-phase HPLC revealed fragmentation patterns in the presence of stoichiometric nickel that were distinct from the cleavage of apo-NikR. Digestion of Cu(II)-NikR produced fragmentation that was similar, although less dramatic, to that produced with Ni(II)-NikR, whereas the Zn(II)- and Co(II)-bound proteins were digested in a similar manner as apo-NikR. Digestion fragments were collected, identified by MALDI-MS, and then mapped onto the available crystal structure of NikR. Although the specificity of the proteases utilized differed, the data suggest that Ni(II) has a selective allosteric effect and that upon metal binding the NikR metal-binding pocket is oriented or protected in such a way as to present itself for digestion in a unique conformation. This data sheds light on the Ni(II)-selective conformational changes that allow NikR to bind DNA optimally and repress transcription of the nik operon.
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Affiliation(s)
- Alistair V Dias
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, M5S 3H6, Canada
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37
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Karmakar S, Cummings RD, McEver RP. Contributions of Ca2+ to galectin-1-induced exposure of phosphatidylserine on activated neutrophils. J Biol Chem 2005; 280:28623-31. [PMID: 15929990 DOI: 10.1074/jbc.m414140200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apoptotic cells redistribute phosphatidylserine (PS) to the cell surface by both Ca(2+)-dependent and -independent mechanisms. Binding of dimeric galectin-1 (dGal-1) to glycoconjugates on N-formyl-Met-Leu-Phe (fMLP)-activated neutrophils exposes PS and facilitates neutrophil phagocytosis by macrophages, yet it does not initiate apoptosis. We asked whether dGal-1 initiated Ca(2+) fluxes that are required to redistribute PS to the surface of activated neutrophils. Prolonged occupancy by dGal-1 was required to maximally mobilize PS to the surfaces of fMLP-activated neutrophils. Like fMLP, dGal-1 rapidly elevated cytosolic Ca(2+) levels in Fluo-4-loaded neutrophils. An initial Ca(2+) mobilization from intracellular stores was followed by movement of extracellular Ca(2+) to the cytosolic compartment, with return to basal Ca(2+) levels within 10 min. Chelation of extracellular Ca(2+) did not prevent PS mobilization. Chelation of intracellular Ca(2+) revealed that fMLP and dGal-1 independently release Ca(2+) from intracellular stores that cooperate to induce optimal redistribution of PS. Ca(2+) mobilization by ionomycin did not permit dGal-1 to mobilize PS, indicating that fMLP initiated both Ca(2+)-dependent and -independent signals that facilitated dGal-1-induced exposure of PS. dGal-1 elevated cytosolic Ca(2+) and mobilized PS through a pathway that required action of Src kinases and phospholipase Cgamma. These results demonstrate that transient Ca(2+) fluxes contribute to a sustained redistribution of PS on neutrophils activated with fMLP and dGal-1.
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Affiliation(s)
- Sougata Karmakar
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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38
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Apuzzo S, Abdelhakim A, Fortin AS, Gros P. Cross-talk between the paired domain and the homeodomain of Pax3: DNA binding by each domain causes a structural change in the other domain, supporting interdependence for DNA Binding. J Biol Chem 2004; 279:33601-12. [PMID: 15148315 DOI: 10.1074/jbc.m402949200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Pax3 protein has two DNA binding domains, a Paired domain (PD) and a paired-type Homeo domain (HD). Although the PD and HD can bind to cognate DNA sequences when expressed individually, genetic and biochemical data indicate that the two domains are functionally interdependent in intact Pax3. The mechanistic basis of this functional interdependence is unknown and was studied by protease sensitivity. Pax3 was modified by the creation of Factor Xa cleavage sites at discrete locations in the PD, the HD, and in the linker segment joining the PD and the HD (Xa172, Xa189, and Xa216) in individual Pax3 mutants. The effect of Factor Xa insertions on protein stability and on DNA binding by the PD and the HD was measured using specific target site sequences. Independent insertions at position 100 in the linker separating the first from the second helix-turn-helix motif of the PD and at position 216 immediately upstream of the HD were found to be readily accessible to Factor Xa cleavage. The effect of DNA binding by the PD or the HD on accessibility of Factor Xa sites inserted in the same or in the other domain was monitored and quantitated for multiple mutants bearing different numbers of Xa sites at each position. In general, DNA binding reduced accessibility of all sites, suggesting a more compact and less solvent-exposed structure of DNA-bound versus DNA-free Pax3. Results of dose response and time course experiments were consistent and showed that DNA binding by the PD not only caused a local structural change in the PD but also caused a conformational change in the HD (P3OPT binding to Xa216 mutants); similarly, DNA binding by the HD also caused a conformational change in the PD (P2 binding to Xa100 mutants). These results provide a structural basis for the functional interdependence of the two DNA binding domains of Pax3.
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Affiliation(s)
- Sergio Apuzzo
- Department of Biochemistry and McGill Cancer Center, McGill University, Quebec H1E 1S9, Canada.
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39
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Rami A, Sims J, Botez G, Winckler J. Spatial resolution of phospholipid scramblase 1 (PLSCR1), caspase-3 activation and DNA-fragmentation in the human hippocampus after cerebral ischemia. Neurochem Int 2003; 43:79-87. [PMID: 12605885 DOI: 10.1016/s0197-0186(02)00194-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Reports on non-neural cells have shown that enhanced activity of the Ca(2+)-dependent/ATP-independent phospholipid scramblase (PLSCR1) is, at least in part, responsible for surface exposure of phosphatidylserine and the collapse of plasma membrane asymmetry in injured or apoptotic cells. To shed some light on mechanisms with a potential to lead to apoptotic death of human neurones following ischemic/hypoxic injury, we examined the immunoreactivity of hippocampal neurones for PLSCR1, caspase-3, cytochrome c and DNA-fragmentation in 22 individuals with clinically symptomatic cerebral ischemia after cardiac arrest or severe hypotension. WE FOUND: (1) significant differences in the percentage of PLSCR1-immunoreactive neurones between controls and short survivors; statistically strong differences between the frequency of immunoreactive neurones among the subfields studied with lowest levels in the CA3; preferential distribution of immunoreactive neurones in controls within the regio entorhinalis, subfield CA1, and hilum. Additionally, these areas exhibited staining of fibre bundles which probably correspond to perforant path, alvear path and collateral's of Schaffer, (2) caspase-3 was upregulated in a region-specific manner with marked activation in the selectively vulnerable hippocampal areas, (3) cytochrome c was redistributed, (4) DNA-fragmentation represented by scattered TUNEL-positive cells increased predominantly during the first 3 days after ischemia, and particularly in the regions of greatest susceptibility to hypoxic injury. This study presents the first evidence that PLSCR1, and probably remodelling of plasma membrane phospholipids (PL), plays a role in ischemic injury in the human hippocampus.
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Affiliation(s)
- A Rami
- Anatomisches Institut III, Universitätsklinikum, Theodor-Stern-Kai 7, 60590, Frankfurt/Main, Germany.
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40
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Yu A, McMaster CR, Byers DM, Ridgway ND, Cook HW. Stimulation of phosphatidylserine biosynthesis and facilitation of UV-induced apoptosis in Chinese hamster ovary cells overexpressing phospholipid scramblase 1. J Biol Chem 2003; 278:9706-14. [PMID: 12509439 DOI: 10.1074/jbc.m204614200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the phospholipid scramblase (PLSCR) family play active roles in altering lipid asymmetry at the plasma membrane including phosphatidylserine (PtdSer) exposure on the cell surface. To determine whether PtdSer biosynthesis and externalization are altered by PLSCR activities during apoptosis, Chinese hamster ovary K1 cell lines stably overexpressing PLSCR1 and PLSCR2 were established. PLSCR1 was localized on the plasma membrane, whereas PLSCR2 was predominantly in the nucleus. Cells overexpressing PLSCR1 showed suppressed growth, altered cell morphology, and higher basal levels of cell death. Following UV irradiation, these cells showed earlier and enhanced PtdSer exposure, increased caspase-3 activation, apoptotic nuclear changes, and PARP cleavage indicative of apoptosis. UV irradiation in cells overexpressing PLSCR1 led to a 4-fold stimulation of PtdSer synthesis (accompanied by increased movement of newly made PtdSer into microvesicles) relative to untreated PLSCR1 cells, whereas PtdSer formation in UV-irradiated vector control cells increased only by 2-fold. No differences in these responses were observed between PLSCR2-expressing cells and vector controls. PtdSer synthesis and its transbilayer movement stimulated by PLSCR1 overexpression were blocked by a caspase inhibitor along with progression of apoptosis. Thus, our studies showed that overexpression of PLSCR1 in Chinese hamster ovary K1 cells stimulated caspase-dependent PtdSer externalization and synthesis, implying an up-regulation of PtdSer formation in response to enhanced outward movement of this phospholipid to the cell surface during apoptosis. PLSCR1 also appears to influence progression of UV-induced apoptosis and could be a point of regulation or intervention during programmed cell death.
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Affiliation(s)
- Anan Yu
- Atlantic Research Centre, Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada
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41
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Abstract
Most biological membranes possess an asymmetric transbilayer distribution of phospholipids. Endogenous enzymes expend energy to maintain the arrangement by promoting the rate of phospholipid translocation, or flip-flop. Researchers have discovered ways to modify this distribution through the use of chemicals. This review presents a critical analysis of the phospholipid asymmetry data in the literature followed by a brief overview of the maintenance and physiological consequences of phospholipid asymmetry, and finishes with a list of chemical ways to alter phospholipid distribution by enhancement of flip-flop.
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Affiliation(s)
- J Middleton Boon
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA
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42
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Abstract
Ingestion by professional or amateur phagocytes is the fate of most cells that undergo apoptosis. Studies in both Caenorhabditis elegans and mammals are now converging to reveal some of the key mechanisms and consequences of this removal process. At least seven corpse removal genes in nematodes have mammalian equivalents, and represent elements of signaling pathways involved in uptake. In mammals, a wide variety of apoptotic cell recognition receptors has been implicated and appears to be divided into two categories, involved in tethering the apoptotic cell or triggering an uptake mechanism related to macropinocytosis. Apoptotic cell removal is normally efficient and non-inflammatory. By contrast, the process may become subverted by parasites to yield a more favorable growth environment, or in other cases lead to fibrosis. Removal may also clinch the apoptotic process itself in cells not yet completely committed to death.
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Affiliation(s)
- P M Henson
- Program in Cell Biology and Department of Pediatrics, National Jewish Medical and Research Center, 1400 Jackson Street, Denver, Colorado 80206, USA.
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43
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Daleke DL, Lyles JV. Identification and purification of aminophospholipid flippases. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1486:108-27. [PMID: 10856717 DOI: 10.1016/s1388-1981(00)00052-4] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Transbilayer phospholipid asymmetry is a common structural feature of most biological membranes. This organization of lipids is generated and maintained by a number of phospholipid transporters that vary in lipid specificity, energy requirements and direction of transport. These transporters can be divided into three classes: (1) bidirectional, non-energy dependent 'scramblases', and energy-dependent transporters that move lipids (2) toward ('flippases') or (3) away from ('floppases') the cytofacial surface of the membrane. One of the more elusive members of this family is the plasma membrane aminophospholipid flippase, which selectively transports phosphatidylserine from the external to the cytofacial monolayer of the plasma membrane. This review summarizes the characteristics of aminophospholipid flippase activity in intact cells and describes current strategies to identify and isolate this protein. The biochemical characteristics of candidate flippases are critically compared and their potential role in flippase activity is evaluated.
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Affiliation(s)
- D L Daleke
- Department of Biochemistry and Molecular Biology and Medical Sciences Program, Indiana University, Bloomington 47405, USA.
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44
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Transcriptional control of the human plasma membranephospholipid scramblase 1 gene is mediated by interferon-α. Blood 2000. [DOI: 10.1182/blood.v95.8.2593] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractInterferons (IFNs) mediate their diverse biologic activities through induction of the expression of multiple genes. Whereas the mode of action of certain of these IFN-regulated genes has been well characterized, most of the molecular and cellular events underlying the constellation of biologic responses to the IFNs remain unresolved. This study showed that the newly identified PLSCR1 gene for phospholipid scramblase, previously implicated in remodeling of plasma membrane phospholipids, is regulated at the transcriptional level by IFN-. Analysis of 5′ flanking genomic sequence in reporter constructs showed that transcriptional control of PLSCR1 was entirely regulated by a single IFN-stimulated response element located in the first exon. A similar induction of PLSCR1 by IFN-2a was also observed in a variety of other human tumor cell lines as well as in human umbilical vein endothelial cells. In these cell lines, the marked IFN-2a–induced increase in PLSCR1 protein expression, ranging as high as 10-fold above basal levels, was not accompanied by increased cell surface exposure of phosphatidylserine, suggesting that remodeling of the cell surface requires both exposure to IFN and a second yet-to-be identified event to stimulate plasma membrane phospholipid scramblase activity and to mobilize phosphatidylserine to the cell surface.
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45
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Abstract
Interferons (IFNs) mediate their diverse biologic activities through induction of the expression of multiple genes. Whereas the mode of action of certain of these IFN-regulated genes has been well characterized, most of the molecular and cellular events underlying the constellation of biologic responses to the IFNs remain unresolved. This study showed that the newly identified PLSCR1 gene for phospholipid scramblase, previously implicated in remodeling of plasma membrane phospholipids, is regulated at the transcriptional level by IFN-. Analysis of 5′ flanking genomic sequence in reporter constructs showed that transcriptional control of PLSCR1 was entirely regulated by a single IFN-stimulated response element located in the first exon. A similar induction of PLSCR1 by IFN-2a was also observed in a variety of other human tumor cell lines as well as in human umbilical vein endothelial cells. In these cell lines, the marked IFN-2a–induced increase in PLSCR1 protein expression, ranging as high as 10-fold above basal levels, was not accompanied by increased cell surface exposure of phosphatidylserine, suggesting that remodeling of the cell surface requires both exposure to IFN and a second yet-to-be identified event to stimulate plasma membrane phospholipid scramblase activity and to mobilize phosphatidylserine to the cell surface.
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46
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Gu C, Cooper DM. Ca(2+), Sr(2+), and Ba(2+) identify distinct regulatory sites on adenylyl cyclase (AC) types VI and VIII and consolidate the apposition of capacitative cation entry channels and Ca(2+)-sensitive ACs. J Biol Chem 2000; 275:6980-6. [PMID: 10702261 DOI: 10.1074/jbc.275.10.6980] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca(2+)-sensitive adenylyl cyclases may act as early integrators of the two major second messenger-signaling pathways mediated by Ca(2+) and cAMP. Ca(2+) stimulation of adenylyl cyclase type I (ACI) and adenylyl cyclase type VIII (ACVIII) is mediated by calmodulin and the site on these adenylyl cyclases that interacts with calmodulin has been defined. By contrast, the mechanism whereby Ca(2+) inhibits adenylyl cyclase type V (ACV) and adenylyl cyclase type VI (ACVI) is unknown. In this study, Ca(2+), Sr(2+), and Ba(2+) were compared to probe the involvement of E-F hand-like domains in both Ca(2+) stimulation and inhibition of ACVIII and ACVI, respectively. HEK 293 cells transfected with ACVIII cDNA and C6-2B glioma cells (where the endogenous adenylyl cyclases is predominantly ACVI) were used to compare the effects of these three cations in in vitro and in vivo measurements. The in vitro data identified two Ca(2+) regulatory sites for both ACVIII and ACVI. Strikingly different potency series for these cations at mediating high affinity stimulation and inhibition of ACVIII and ACVI, respectively, effectively rule out the possibility that calmodulin or proteins utilizing similar Ca(2+)-binding motifs mediate inhibition of ACVI. On the other hand, the low affinity inhibition that is common to both ACVIII and ACVI showed virtually identical potency profiles for the IIa cation series, indicating a common site of action. Remarkably, whereas Sr(2+) was rather ineffective at regulating these cyclases (particularly ACVI) in vitro, adequate concentrations accumulated in the vicinity of these enzymes as a consequence of capacitative cation entry to partially regulate both of these activities in vivo. This latter finding consolidates earlier observations that Ca(2+)-sensitive adenylyl cyclases detect and respond to capacitative cation entry rather than global cytosolic cation concentrations.
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Affiliation(s)
- C Gu
- Neuroscience Program, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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47
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Andersen H, Greenberg DL, Fujikawa K, Xu W, Chung DW, Davie EW. Protease-activated receptor 1 is the primary mediator of thrombin-stimulated platelet procoagulant activity. Proc Natl Acad Sci U S A 1999; 96:11189-93. [PMID: 10500152 PMCID: PMC18009 DOI: 10.1073/pnas.96.20.11189] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The activation of human platelets by thrombin is mediated primarily by protease-activated receptors (PARs). PAR1 and PAR4 are present on human platelets and are activated by the hexapeptides SFLLRN and GYPGQV, respectively. To further characterize the involvement of PAR1 and PAR4 in platelet activation, the ability of SFLLRN or GYPGQV to generate annexin V binding to newly exposed phospholipids on the platelet surface and generate procoagulant activity has been examined. Exposure of phosphatidylserine and phosphatidylethanolamine on platelets, as determined by an increase in annexin V binding, was strongly stimulated by SFLLRN, thrombin, and collagen, but only to a minor extent by GYPGQV. In a clotting assay initiated with factor VIIa, soluble tissue factor, and calcium, the clotting time in the absence of platelets was >5 min. In the presence of unstimulated platelets, the clotting time was 200 +/- 20 sec. In the presence of platelets activated with SFLLRN or collagen, the clotting time decreased to 100 +/- 10 sec. This shortening of the clotting time is equivalent to about a 5-fold increase in coagulant activity when stimulated platelets are compared with unstimulated platelets and activated platelets are used as a reference. These results indicate that thrombin initiates a very strong response in platelets through PAR1, leading to exposure of anionic phospholipids that support blood clotting. The response mediated by PAR4, however, was limited to platelet aggregation and similar to that triggered in platelets by weaker agonists such as ADP or epinephrine.
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Affiliation(s)
- H Andersen
- Department of Biochemistry, University of Washington, Box 357350, Seattle, WA 98195, USA
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48
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Bevers EM, Comfurius P, Dekkers DW, Zwaal RF. Lipid translocation across the plasma membrane of mammalian cells. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1439:317-30. [PMID: 10446420 DOI: 10.1016/s1388-1981(99)00110-9] [Citation(s) in RCA: 286] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The plasma membrane, which forms the physical barrier between the intra- and extracellular milieu, plays a pivotal role in the communication of cells with their environment. Exchanging metabolites, transferring signals and providing a platform for the assembly of multi-protein complexes are a few of the major functions of the plasma membrane, each of which requires participation of specific membrane proteins and/or lipids. It is therefore not surprising that the two leaflets of the membrane bilayer each have their specific lipid composition. Although membrane lipid asymmetry has been known for many years, the mechanisms for maintaining or regulating the transbilayer lipid distribution are still not completely understood. Three major players have been presented over the past years: (1) an inward-directed pump specific for phosphatidylserine and phosphatidylethanolamine, known as aminophospholipid translocase; (2) an outward-directed pump referred to as 'floppase' with little selectivity for the polar headgroup of the phospholipid, but whose actual participation in transport of endogenous lipids has not been well established; and (3) a lipid scramblase, which facilitates bi-directional migration across the bilayer of all phospholipid classes, independent of the polar headgroup. Whereas a concerted action of aminophospholipid translocase and floppase could, in principle, account for the maintenance of lipid asymmetry in quiescent cells, activation of the scramblase and concomitant inhibition of the aminophospholipid translocase causes a collapse of lipid asymmetry, manifested by exposure of phosphatidylserine on the cell surface. In this article, each of these transporters will be discussed, and their physiological importance will be illustrated by the Scott syndrome, a bleeding disorder caused by impaired lipid scrambling. Finally, phosphatidylserine exposure during apoptosis will be briefly discussed in relation to inhibition of translocase and simultaneous activation of scramblase.
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Affiliation(s)
- E M Bevers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
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