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Alam R, Biswas S, Haque F, Pathan MT, Imon RR, Talukder MEK, Samad A, Asseri AH, Ahammad F. A systematic analysis of ATPase Cation transporting 13A2 (ATP13A2) transcriptional expression and prognostic value in human brain cancer. Biomed Signal Process Control 2022. [DOI: 10.1016/j.bspc.2021.103183] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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2
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Benedikter BJ, Weseler AR, Wouters EFM, Savelkoul PHM, Rohde GGU, Stassen FRM. Redox-dependent thiol modifications: implications for the release of extracellular vesicles. Cell Mol Life Sci 2018; 75:2321-2337. [PMID: 29594387 PMCID: PMC5986851 DOI: 10.1007/s00018-018-2806-z] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/09/2018] [Accepted: 03/22/2018] [Indexed: 02/07/2023]
Abstract
Extracellular vesicles (EVs), including microvesicles and exosomes, are emerging as important regulators of homeostasis and pathophysiology. During pro-inflammatory and pro-oxidant conditions, EV release is induced. As EVs released under such conditions often exert pro-inflammatory and procoagulant effects, they may actively promote the pathogenesis of chronic diseases. There is evidence that thiol group-containing antioxidants can prevent EV induction by pro-inflammatory and oxidative stimuli, likely by protecting protein thiols of the EV-secreting cells from oxidation. As the redox state of protein thiols greatly impacts three-dimensional protein structure and, consequently, function, redox modifications of protein thiols may directly modulate EV release in response to changes in the cell's redox environment. In this review article, we discuss targets of redox-dependent thiol modifications that are known or expected to be involved in the regulation of EV release, namely redox-sensitive calcium channels, N-ethylmaleimide sensitive factor, protein disulfide isomerase, phospholipid flippases, actin filaments, calpains and cell surface-exposed thiols. Thiol protection is proposed as a strategy for preventing detrimental changes in EV signaling in response to inflammation and oxidative stress. Identification of the thiol-containing proteins that modulate EV release in pro-oxidant environments could provide a rationale for broad application of thiol group-containing antioxidants in chronic inflammatory diseases.
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Affiliation(s)
- Birke J Benedikter
- Department of Medical Microbiology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands
- Department of Respiratory Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands
| | - Antje R Weseler
- Department of Pharmacology and Toxicology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands
| | - Emiel F M Wouters
- Department of Respiratory Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands
| | - Paul H M Savelkoul
- Department of Medical Microbiology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands
- Department of Medical Microbiology and Infection Control, VU University Medical Center, P.O. Box 7057, 1007 MB, Amsterdam, The Netherlands
| | - Gernot G U Rohde
- Medical Clinic I, Department of Respiratory Medicine, Goethe University Hospital, Frankfurt/Main, Germany
| | - Frank R M Stassen
- Department of Medical Microbiology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands.
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3
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Kerr DJ, Marsillo A, Guariglia SR, Budylin T, Sadek R, Menkes S, Chauhan A, Wen GY, McCloskey DP, Wieraszko A, Banerjee P. Aberrant hippocampal Atp8a1 levels are associated with altered synaptic strength, electrical activity, and autistic-like behavior. Biochim Biophys Acta Mol Basis Dis 2016; 1862:1755-65. [PMID: 27287255 DOI: 10.1016/j.bbadis.2016.06.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 05/06/2016] [Accepted: 06/05/2016] [Indexed: 12/18/2022]
Abstract
Type IV ATPases are putative aminophospholipid translocases (APLTs), more commonly known as flippases. A pronounced induction of the flippase Atp8a1 was observed in post-mortem tissue homogenates from the hippocampus and temporal lobe of juvenile autistic subjects compared to age-matched controls. In order to simulate the human data, C57BL/6 mice were allowed to develop after intra-hippocampal injection of recombinant lentivirus expressing Atp8a1 at the early developmental stage of postnatal day 6 (P6). Transmission electron microscopy (TEM) analysis of the lentivirus-Atp8a1 treated (Atp8a1+) mice in adulthood revealed fewer and weaker excitatory synapses in the hippocampal CA1 region compared to mice injected with empty virus. Significant inhibition of the Schaffer collateral pathway was observed in the Atp8a1+ mice in paired-pulse recording (PPR) at 20-ms inter-stimulus interval. In the three-chambered sociability test, the Atp8a1+ mice displayed no preference for an encaged stranger mouse over a novel object, which is a characteristic autistic-like behavior. In sharp contrast, Atp8a1 (-/-) mice displayed a preference for a stranger mouse over the novel object, which is characteristic of neurotypical mouse behavior. However, similar to the Atp8a1+ mice, the Atp8a1 (-/-) mice harbored fewer and weaker excitatory synapses in CA1 compared to wild-type controls, and displayed inhibition at 20-ms inter-stimulus interval in PPR. These findings suggest that both elevated and diminished levels of Atp8a1 during early development are detrimental to brain connectivity, but only elevated Atp8a1 is associated with aberrant social behavior. Mice with augmented levels of Atp8a1 may therefore serve as a potential model in autism research.
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Affiliation(s)
- Daniel J Kerr
- Doctoral Program in Biology (CUNY), The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Alexandra Marsillo
- Doctoral Program in Biology (CUNY), The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Sara R Guariglia
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, United States
| | - Tatyana Budylin
- Doctoral Program in Biology (CUNY), The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Rodina Sadek
- Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Silvia Menkes
- Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Abha Chauhan
- New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, United States
| | - Guang Y Wen
- Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States; New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, United States
| | - Daniel P McCloskey
- Doctoral Program in Psychology, CUNY Graduate Center, New York, NY 10016, United States; Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Andrzej Wieraszko
- Department of Biology, The College of Staten Island (CUNY), Staten Island, NY 10314, United States; Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Probal Banerjee
- Doctoral Program in Biology (CUNY), The College of Staten Island (CUNY), Staten Island, NY 10314, United States; Department of Chemistry, The College of Staten Island (CUNY), Staten Island, NY 10314, United States; Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States.
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4
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Nagata S, Suzuki J, Segawa K, Fujii T. Exposure of phosphatidylserine on the cell surface. Cell Death Differ 2016; 23:952-61. [PMID: 26891692 DOI: 10.1038/cdd.2016.7] [Citation(s) in RCA: 315] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/11/2016] [Indexed: 12/15/2022] Open
Abstract
Phosphatidylserine (PtdSer) is a phospholipid that is abundant in eukaryotic plasma membranes. An ATP-dependent enzyme called flippase normally keeps PtdSer inside the cell, but PtdSer is exposed by the action of scramblase on the cell's surface in biological processes such as apoptosis and platelet activation. Once exposed to the cell surface, PtdSer acts as an 'eat me' signal on dead cells, and creates a scaffold for blood-clotting factors on activated platelets. The molecular identities of the flippase and scramblase that work at plasma membranes have long eluded researchers. Indeed, their identity as well as the mechanism of the PtdSer exposure to the cell surface has only recently been revealed. Here, we describe how PtdSer is exposed in apoptotic cells and in activated platelets, and discuss PtdSer exposure in other biological processes.
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Affiliation(s)
- S Nagata
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - J Suzuki
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - K Segawa
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - T Fujii
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
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5
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Andersen JP, Vestergaard AL, Mikkelsen SA, Mogensen LS, Chalat M, Molday RS. P4-ATPases as Phospholipid Flippases-Structure, Function, and Enigmas. Front Physiol 2016; 7:275. [PMID: 27458383 PMCID: PMC4937031 DOI: 10.3389/fphys.2016.00275] [Citation(s) in RCA: 213] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 06/20/2016] [Indexed: 01/26/2023] Open
Abstract
P4-ATPases comprise a family of P-type ATPases that actively transport or flip phospholipids across cell membranes. This generates and maintains membrane lipid asymmetry, a property essential for a wide variety of cellular processes such as vesicle budding and trafficking, cell signaling, blood coagulation, apoptosis, bile and cholesterol homeostasis, and neuronal cell survival. Some P4-ATPases transport phosphatidylserine and phosphatidylethanolamine across the plasma membrane or intracellular membranes whereas other P4-ATPases are specific for phosphatidylcholine. The importance of P4-ATPases is highlighted by the finding that genetic defects in two P4-ATPases ATP8A2 and ATP8B1 are associated with severe human disorders. Recent studies have provided insight into how P4-ATPases translocate phospholipids across membranes. P4-ATPases form a phosphorylated intermediate at the aspartate of the P-type ATPase signature sequence, and dephosphorylation is activated by the lipid substrate being flipped from the exoplasmic to the cytoplasmic leaflet similar to the activation of dephosphorylation of Na(+)/K(+)-ATPase by exoplasmic K(+). How the phospholipid is translocated can be understood in terms of a peripheral hydrophobic gate pathway between transmembrane helices M1, M3, M4, and M6. This pathway, which partially overlaps with the suggested pathway for migration of Ca(2+) in the opposite direction in the Ca(2+)-ATPase, is wider than the latter, thereby accommodating the phospholipid head group. The head group is propelled along against its concentration gradient with the hydrocarbon chains projecting out into the lipid phase by movement of an isoleucine located at the position corresponding to an ion binding glutamate in the Ca(2+)- and Na(+)/K(+)-ATPases. Hence, the P4-ATPase mechanism is quite similar to the mechanism of these ion pumps, where the glutamate translocates the ions by moving like a pump rod. The accessory subunit CDC50 may be located in close association with the exoplasmic entrance of the suggested pathway, and possibly promotes the binding of the lipid substrate. This review focuses on properties of mammalian and yeast P4-ATPases for which most mechanistic insight is available. However, the structure, function and enigmas associated with mammalian and yeast P4-ATPases most likely extend to P4-ATPases of plants and other organisms.
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Affiliation(s)
| | | | | | | | - Madhavan Chalat
- Department of Biochemistry and Molecular Biology, University of British ColumbiaVancouver, BC, Canada
| | - Robert S. Molday
- Department of Biochemistry and Molecular Biology, University of British ColumbiaVancouver, BC, Canada
- *Correspondence: Robert S. Molday
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6
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Montigny C, Lyons J, Champeil P, Nissen P, Lenoir G. On the molecular mechanism of flippase- and scramblase-mediated phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:767-783. [PMID: 26747647 DOI: 10.1016/j.bbalip.2015.12.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/20/2015] [Accepted: 12/28/2015] [Indexed: 11/20/2022]
Abstract
Phospholipid flippases are key regulators of transbilayer lipid asymmetry in eukaryotic cell membranes, critical to many trafficking and signaling pathways. P4-ATPases, in particular, are responsible for the uphill transport of phospholipids from the exoplasmic to the cytosolic leaflet of the plasma membrane, as well as membranes of the late secretory/endocytic pathways, thereby establishing transbilayer asymmetry. Recent studies combining cell biology and biochemical approaches have improved our understanding of the path taken by lipids through P4-ATPases. Additionally, identification of several protein families catalyzing phospholipid 'scrambling', i.e. disruption of phospholipid asymmetry through energy-independent bi-directional phospholipid transport, as well as the recent report of the structure of such a scramblase, opens the way to a deeper characterization of their mechanism of action. Here, we discuss the molecular nature of the mechanism by which lipids may 'flip' across membranes, with an emphasis on active lipid transport catalyzed by P4-ATPases. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Affiliation(s)
- Cédric Montigny
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Joseph Lyons
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Philippe Champeil
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Poul Nissen
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Guillaume Lenoir
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France.
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7
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Yabas M, Coupland LA, Cromer D, Winterberg M, Teoh NC, D'Rozario J, Kirk K, Bröer S, Parish CR, Enders A. Mice deficient in the putative phospholipid flippase ATP11C exhibit altered erythrocyte shape, anemia, and reduced erythrocyte life span. J Biol Chem 2014; 289:19531-7. [PMID: 24898253 DOI: 10.1074/jbc.c114.570267] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Transmembrane lipid transporters are believed to establish and maintain phospholipid asymmetry in biological membranes; however, little is known about the in vivo function of the specific transporters involved. Here, we report that developing erythrocytes from mice lacking the putative phosphatidylserine flippase ATP11C showed a lower rate of PS translocation in vitro compared with erythrocytes from wild-type littermates. Furthermore, the mutant mice had an elevated percentage of phosphatidylserine-exposing mature erythrocytes in the periphery. Although erythrocyte development in ATP11C-deficient mice was normal, the mature erythrocytes had an abnormal shape (stomatocytosis), and the life span of mature erythrocytes was shortened relative to that in control littermates, resulting in anemia in the mutant mice. Thus, our findings uncover an essential role for ATP11C in erythrocyte morphology and survival and provide a new candidate for the rare inherited blood disorder stomatocytosis with uncompensated anemia.
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Affiliation(s)
- Mehmet Yabas
- From the Ramaciotti Immunization Genomics Laboratory and
| | - Lucy A Coupland
- Cancer and Vascular Biology Group, Department of Immunology, The John Curtin School of Medical Research, and the Clinical Haematology Unit, The Canberra Hospital, Canberra, Australian Capital Territory 2605, Australia
| | - Deborah Cromer
- the Complex Systems in Biology Group, Centre for Vascular Research, University of New South Wales, Kensington, New South Wales 2052, Australia, and
| | - Markus Winterberg
- the Division of Biomedical Science and Biochemistry, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Narci C Teoh
- the Liver Research Group, Australian National University Medical School at the Canberra Hospital, Canberra, Australian Capital Territory 2605, Australia
| | - James D'Rozario
- the Clinical Haematology Unit, The Canberra Hospital, Canberra, Australian Capital Territory 2605, Australia
| | - Kiaran Kirk
- the Division of Biomedical Science and Biochemistry, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Stefan Bröer
- the Division of Biomedical Science and Biochemistry, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Christopher R Parish
- Cancer and Vascular Biology Group, Department of Immunology, The John Curtin School of Medical Research, and
| | - Anselm Enders
- From the Ramaciotti Immunization Genomics Laboratory and
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8
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Coleman JA, Quazi F, Molday RS. Mammalian P4-ATPases and ABC transporters and their role in phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:555-74. [PMID: 23103747 DOI: 10.1016/j.bbalip.2012.10.006] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/16/2012] [Accepted: 10/18/2012] [Indexed: 02/08/2023]
Abstract
Transport of phospholipids across cell membranes plays a key role in a wide variety of biological processes. These include membrane biosynthesis, generation and maintenance of membrane asymmetry, cell and organelle shape determination, phagocytosis, vesicle trafficking, blood coagulation, lipid homeostasis, regulation of membrane protein function, apoptosis, etc. P(4)-ATPases and ATP binding cassette (ABC) transporters are the two principal classes of membrane proteins that actively transport phospholipids across cellular membranes. P(4)-ATPases utilize the energy from ATP hydrolysis to flip aminophospholipids from the exocytoplasmic (extracellular/lumen) to the cytoplasmic leaflet of cell membranes generating membrane lipid asymmetry and lipid imbalance which can induce membrane curvature. Many ABC transporters play crucial roles in lipid homeostasis by actively transporting phospholipids from the cytoplasmic to the exocytoplasmic leaflet of cell membranes or exporting phospholipids to protein acceptors or micelles. Recent studies indicate that some ABC proteins can also transport phospholipids in the opposite direction. The importance of P(4)-ATPases and ABC transporters is evident from the findings that mutations in many of these transporters are responsible for severe human genetic diseases linked to defective phospholipid transport. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
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9
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Stone A, Chau C, Eaton C, Foran E, Kapur M, Prevatt E, Belkin N, Kerr D, Kohlin T, Williamson P. Biochemical characterization of P4-ATPase mutations identified in patients with progressive familial intrahepatic cholestasis. J Biol Chem 2012; 287:41139-51. [PMID: 23060447 DOI: 10.1074/jbc.m112.413039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Mutations in the P4-ATPase ATP8B1 cause the inherited liver disease progressive familial intrahepatic cholestasis. Several of these mutations are located in conserved regions of the transmembrane domain associated with substrate binding and transport. Assays for P4-ATPase-mediated transport in living yeast cells were developed and used to characterize the specificity and kinetic parameters of this transport. Progressive familial intrahepatic cholestasis mutations were introduced into the yeast plasma membrane P4-ATPase Dnf2p, and the effect of these mutations on its catalysis of phospholipid transport were determined. The results of these measurements have implications for the basis of the disease and for the mechanism of phospholipid transit through the enzyme during the reaction cycle.
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Affiliation(s)
- Alex Stone
- Department of Biology, Amherst College, Amherst, Massachusetts 01002, USA
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10
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Sebastian TT, Baldridge RD, Xu P, Graham TR. Phospholipid flippases: building asymmetric membranes and transport vesicles. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:1068-77. [PMID: 22234261 DOI: 10.1016/j.bbalip.2011.12.007] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 12/14/2011] [Accepted: 12/16/2011] [Indexed: 01/25/2023]
Abstract
Phospholipid flippases in the type IV P-type ATPase family (P4-ATPases) are essential components of the Golgi, plasma membrane and endosomal system that play critical roles in membrane biogenesis. These pumps flip phospholipid across the bilayer to create an asymmetric membrane structure with substrate phospholipids, such as phosphatidylserine and phosphatidylethanolamine, enriched within the cytosolic leaflet. The P4-ATPases also help form transport vesicles that bud from Golgi and endosomal membranes, thereby impacting the sorting and localization of many different proteins in the secretory and endocytic pathways. At the organismal level, P4-ATPase deficiencies are linked to liver disease, obesity, diabetes, hearing loss, neurological deficits, immune deficiency and reduced fertility. Here, we review the biochemical, cellular and physiological functions of P4-ATPases, with an emphasis on their roles in vesicle-mediated protein transport. This article is part of a Special Issue entitled Lipids and Vesicular Transport.
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Affiliation(s)
- Tessy T Sebastian
- Department of Biological Sciences, Vanderbilt University, Nashville TN 37235, USA
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11
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Levano K, Punia V, Raghunath M, Debata PR, Curcio GM, Mogha A, Purkayastha S, McCloskey D, Fata J, Banerjee P. Atp8a1 deficiency is associated with phosphatidylserine externalization in hippocampus and delayed hippocampus-dependent learning. J Neurochem 2011; 120:302-13. [PMID: 22007859 DOI: 10.1111/j.1471-4159.2011.07543.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The molecule responsible for the enzyme activity plasma membrane (PM) aminophospholipid translocase (APLT), which catalyzes phosphatidylserine (PS) translocation from the outer to the inner leaflet of the plasma membrane, is unknown in mammals. A Caenorhabditis elegans study has shown that ablation of transbilayer amphipath transporter-1 (TAT-1), which is an ortholog of a mammalian P-type ATPase, Atp8a1, causes PS externalization in the germ cells. We demonstrate here that the hippocampal cells of the dentate gyrus, and Cornu Ammonis (CA1, CA3) in mice lacking Atp8a1 exhibit a dramatic increase in PS externalization. Although their hippocampi showed no abnormal morphology or heightened apoptosis, these mice displayed increased activity and a marked deficiency in hippocampus-dependent learning, but no hyper-anxiety. Such observations indicate that Atp8a1 plays a crucial role in PM-APLT activity in the neuronal cells. In corroboration, ectopic expression of Atp8a1 but not its close homolog, Atp8a2, caused an increase in the population (V(max) ) of PM-APLT without any change in its signature parameter K(m) in the neuronal N18 cells. Conversely, expression of a P-type phosphorylation-site mutant of Atp8a1 (Atp8a1*) caused a decrease in V(max) of PM-APLT without significantly altering its K(m) . The Atp8a1*-expressing N18 cells also exhibited PS externalization without apoptosis. Together, our data strongly indicate that Atp8a1 plays a central role in the PM-APLT activity of some mammalian cells, such as the neuronal N18 and hippocampal cells.
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Affiliation(s)
- Kelly Levano
- CUNY Doctoral Program in Biochemistry, City University of New York at the College of Staten Island, Staten Island, New York, USA
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12
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Affiliation(s)
- Michael G. Palmgren
- Center for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, University of Copenhagen, DK-1871 Frederiksberg C, Denmark;
| | - Poul Nissen
- Center for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus University, DK-8000 Århus C, Denmark;
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13
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Tanaka K, Fujimura-Kamada K, Yamamoto T. Functions of phospholipid flippases. J Biochem 2010; 149:131-43. [PMID: 21134888 DOI: 10.1093/jb/mvq140] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Asymmetrical distribution of phospholipids is generally observed in the eukaryotic plasma membrane. Maintenance and changes of this phospholipid asymmetry are regulated by ATP-driven phospholipid translocases. Accumulating evidence indicates that type 4 P-type ATPases (P4-ATPases, also called flippases) translocate phospholipids from the exoplasmic leaflet to the cytoplasmic leaflet of the plasma membrane and internal membranes. Among P-type ATPases, P4-ATPases are unique in that they are associated with a conserved membrane protein of the Cdc50 family as a non-catalytic subunit. Recent studies indicate that flippases are involved in various cellular functions, including transport vesicle formation and cell polarity. In this review, we will focus on the functional aspect of phospholipid flippases.
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Affiliation(s)
- Kazuma Tanaka
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo, Japan.
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14
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Coleman JA, Kwok MCM, Molday RS. Localization, purification, and functional reconstitution of the P4-ATPase Atp8a2, a phosphatidylserine flippase in photoreceptor disc membranes. J Biol Chem 2009; 284:32670-9. [PMID: 19778899 DOI: 10.1074/jbc.m109.047415] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
P(4)-ATPases comprise a relatively new subfamily of P-type ATPases implicated in the energy-dependent translocation of aminophospholipids across cell membranes. In this study, we report on the localization and functional properties of Atp8a2, a member of the P(4)-ATPase subfamily that has not been studied previously. Reverse transcription-PCR revealed high expression of atp8a2 mRNA in the retina and testis. Within the retina, immunofluorescence microscopy and subcellular fractionation studies localized Atp8a2 to outer segment disc membranes of rod and cone photoreceptor cells. Atp8a2 purified from photoreceptor outer segments by immunoaffinity chromatography exhibited ATPase activity that was stimulated by phosphatidylserine and to a lesser degree phosphatidylethanolamine but not by phosphatidylcholine or other membrane lipids. Purified Atp8a2 was reconstituted into liposomes containing fluorescent-labeled phosphatidylserine to measure the ability of Atp8a2 to flip phosphatidylserine across the lipid bilayer. Fluorescence measurements showed that Atp8a2 flipped fluorescent-labeled phosphatidylserine from the inner leaflet of liposomes (equivalent to the exocytoplasmic leaflet of cell membranes) to the outer leaflet (equivalent to cytoplasmic leaflet) in an ATP-dependent manner. Our studies provide the first direct biochemical evidence that purified P(4)-ATPases can translocate aminophospholipids across membranes and further implicates Atp8a2 in the generation and maintenance of phosphatidylserine asymmetry in photoreceptor disc membranes.
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Affiliation(s)
- Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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15
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Abstract
Robust lipid traffic within and among membranes is essential for cell growth and membrane biogenesis. Many of these transport reactions occur by nonvesicular pathways, and the genetic and biochemical details of these processes are now beginning to emerge. Intramembrane lipid transport reactions utilize P-type ATPases, ABC transporters, scramblases, and Niemann-Pick type C (NPC) family proteins. The intramembrane processes regulate the establishment and elimination of membrane lipid asymmetry, the cellular influx and efflux of sterols and phospholipids, and the egress of lysosomally deposited lipids. The intermembrane lipid transport processes play important roles in membrane biogenesis, sterol sequestration, and steroid hormone formation. The roles of soluble lipid carriers and membrane-bound lipid-transporting complexes, as well as the mechanisms for regulation of their targeting and assembly, are now becoming apparent. Elucidation of the details of these systems is providing new perspectives on the regulation of lipid traffic within cells.
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Affiliation(s)
- Dennis R Voelker
- Program in Cell Biology, Department of Medicine, National Jewish Health, Denver, CO 80206, USA.
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16
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Abstract
The asymmetric distribution of amino-containing phospholipids in plasma membranes is essential for the function and survival of mammalian cells. Phosphatidylserine (PS) is restricted to the inner leaflet of plasma membranes by an ATP-dependent transport process. Exposure of PS on the surface of cells serves as a binding site for haemostatic factors, triggers cell-cell interaction and recognition by macrophages and phospholipases. Exposure of PS on the red cell surface plays a significant role in sickle cell pathology. We report the identification of two different isoforms of the aminophospholipid translocase, Atp8a1, or flippase, in the murine red blood cell membrane.
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Affiliation(s)
- Eric Soupene
- Children's Hospital Oakland Research Institute, Martin Luther King Jr Way, Oakland, CA 94609, USA.
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17
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Devaux PF, López-Montero I, Bryde S. Proteins involved in lipid translocation in eukaryotic cells. Chem Phys Lipids 2006; 141:119-32. [PMID: 16600198 DOI: 10.1016/j.chemphyslip.2006.02.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 02/20/2006] [Indexed: 11/17/2022]
Abstract
Since the first discovery of ATP-dependent translocation of lipids in the human erythrocyte membrane in 1984, there has been much evidence of the existence of various ATPases translocating lipids in eukaryotic cell membranes. They include P-type ATPases involved in inwards lipid transport from the exoplasmic leaflet to the cytosolic leaflet and ABC proteins involved in outwards transport. There are also ATP-independent proteins that catalyze the passage of lipids in both directions. Five P-type ATPase involved in lipid transport have been genetically characterized in yeast cells, suggesting a pool of several proteins with partially redundant activities responsible for the regulation of lipid asymmetry. However, expression and purification of individual yeast proteins is still insufficient to allow reconstitution experiments in liposomes. In this review, we want to give an overview over current investigation efforts about the identification and purification of proteins that may be involved in lipid translocation.
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Affiliation(s)
- Philippe F Devaux
- Institut de Biologie Physico-Chimique, UMR CNRS 7099, Paris, France.
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18
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Paterson JK, Renkema K, Burden L, Halleck MS, Schlegel RA, Williamson P, Daleke DL. Lipid Specific Activation of the Murine P4-ATPase Atp8a1 (ATPase II)†. Biochemistry 2006; 45:5367-76. [PMID: 16618126 DOI: 10.1021/bi052359b] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The asymmetric transbilayer distribution of phosphatidylserine (PS) in the mammalian plasma membrane and secretory vesicles is maintained, in part, by an ATP-dependent transporter. This aminophospholipid "flippase" selectively transports PS to the cytosolic leaflet of the bilayer and is sensitive to vanadate, Ca(2+), and modification by sulfhydryl reagents. Although the flippase has not been positively identified, a subfamily of P-type ATPases has been proposed to function as transporters of amphipaths, including PS and other phospholipids. A candidate PS flippase ATP8A1 (ATPase II), originally isolated from bovine secretory vesicles, is a member of this subfamily based on sequence homology to the founding member of the subfamily, the yeast protein Drs2, which has been linked to ribosomal assembly, the formation of Golgi-coated vesicles, and the maintenance of PS asymmetry. To determine if ATP8A1 has biochemical characteristics consistent with a PS flippase, a murine homologue of this enzyme was expressed in insect cells and purified. The purified Atp8a1 is inactive in detergent micelles or in micelles containing phosphatidylcholine, phosphatidic acid, or phosphatidylinositol, is minimally activated by phosphatidylglycerol or phosphatidylethanolamine (PE), and is maximally activated by PS. The selectivity for PS is dependent upon multiple elements of the lipid structure. Similar to the plasma membrane PS transporter, Atp8a1 is activated only by the naturally occurring sn-1,2-glycerol isomer of PS and not the sn-2,3-glycerol stereoisomer. Both flippase and Atp8a1 activities are insensitive to the stereochemistry of the serine headgroup. Most modifications of the PS headgroup structure decrease recognition by the plasma membrane PS flippase. Activation of Atp8a1 is also reduced by these modifications; phosphatidylserine-O-methyl ester, lysophosphatidylserine, glycerophosphoserine, and phosphoserine, which are not transported by the plasma membrane flippase, do not activate Atp8a1. Weakly translocated lipids (PE, phosphatidylhydroxypropionate, and phosphatidylhomoserine) are also weak Atp8a1 activators. However, N-methyl-phosphatidylserine, which is transported by the plasma membrane flippase at a rate equivalent to PS, is incapable of activating Atp8a1 activity. These results indicate that the ATPase activity of the secretory granule Atp8a1 is activated by phospholipids binding to a specific site whose properties (PS selectivity, dependence upon glycerol but not serine, stereochemistry, and vanadate sensitivity) are similar to, but distinct from, the properties of the substrate binding site of the plasma membrane flippase.
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Affiliation(s)
- Jill K Paterson
- Department of Biochemistry and Molecular Biology, Medical Sciences, Indiana University, Bloomington, Indiana 47405, USA
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19
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Kagan VE, Borisenko GG, Tyurina YY, Tyurin VA, Jiang J, Potapovich AI, Kini V, Amoscato AA, Fujii Y. Oxidative lipidomics of apoptosis: redox catalytic interactions of cytochrome c with cardiolipin and phosphatidylserine. Free Radic Biol Med 2004; 37:1963-85. [PMID: 15544916 DOI: 10.1016/j.freeradbiomed.2004.08.016] [Citation(s) in RCA: 272] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Revised: 08/24/2004] [Accepted: 08/26/2004] [Indexed: 12/16/2022]
Abstract
The primary life-supporting function of cytochrome c (cyt c) is control of cellular energetic metabolism as a mobile shuttle in the electron transport chain of mitochondria. Recently, cyt c's equally important life-terminating function as a trigger and regulator of apoptosis was identified. This dreadful role is realized through the relocalization of mitochondrial cyt c to the cytoplasm where it interacts with Apaf-1 in forming apoptosomes and mediating caspase-9 activation. Although the presence of heme moiety of cyt c is essential for the latter function, cyt c's redox catalytic features are not required. Lately, two other essential functions of cyt c in apoptosis, that may rely heavily on its redox activity have been suggested. Both functions are directed toward oxidation of two negatively charged phospholipids, cardiolipin (CL) in the mitochondria and phosphatidylserine (PS) in the plasma membrane. In both cases, oxidized phospholipids seem to be essential for the transduction of two distinctive apoptotic signals: one is participation of oxidized CL in the formation of the mitochondrial permeability transition pore that facilitates release of cyt c into the cytosol and the other is the contribution of oxidized PS to the externalization and recognition of PS (and possibly oxidized PS) on the cell surface by specialized receptors of phagocytes. In this review, we present a new concept that cyt c actuates both of these oxidative roles through a uniform mechanism: its specific interactions with each of these phospholipids result in the conversion and activation of cyt c, transforming it from an innocuous electron transporter into a calamitous peroxidase capable of oxidizing the activating phospholipids. We also show that this new concept is compatible with a leading role for reactive oxygen species in the execution of the apoptotic program, with cyt c as the main executioner.
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Affiliation(s)
- Valerian E Kagan
- Center for Free Radical and Antioxidant Health, Department of Environmental and Occupational Health, Pittsburgh, PA 15260, USA.
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20
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Abstract
The best-understood mechanisms for generating transport vesicles in the secretory and endocytic pathways involve the localized assembly of cytosolic coat proteins such as clathrin, coat protein complex (COP)I and COPII onto membranes. These coat proteins can deform membranes by themselves, but accessory proteins might help to generate the tight curvature needed to form a vesicle. Enzymes that pump phospholipid from one leaflet of the bilayer to the other (flippases) can deform membranes by creating an imbalance in the phospholipid number between the two leaflets. Recent studies describe a requirement for the yeast Drs2p family of P-type ATPases in both phospholipid translocation and protein transport in the secretory and endocytic pathways. This indicates that flippases work with coat proteins to form vesicles.
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Affiliation(s)
- Todd R Graham
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634, USA.
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21
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Natarajan P, Wang J, Hua Z, Graham TR. Drs2p-coupled aminophospholipid translocase activity in yeast Golgi membranes and relationship to in vivo function. Proc Natl Acad Sci U S A 2004; 101:10614-9. [PMID: 15249668 PMCID: PMC489982 DOI: 10.1073/pnas.0404146101] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Aminophospholipid translocases (APLTs) are defined primarily by their ability to flip fluorescent or spin-labeled derivatives of phosphatidylserine (PS) and phosphatidylethanolamine (PE) from the external leaflet of a membrane bilayer to the cytosolic leaflet and are thought to establish phospholipid asymmetry in biological membranes. The identities of APLTs remain unknown, although candidate proteins include the Drs2p/ATPase II subfamily of P-type ATPases. Drs2p from budding yeast localizes to the trans-Golgi network (TGN), and here we show that this membrane contains an ATP-dependent APLT that flips 7-nitro-2-1,3-benzoxadiazol-4-yl (NBD) PS and PE derivatives from the luminal to the cytosolic leaflet. To assess the contribution of Drs2p to this activity, TGN membranes were prepared from strains harboring WT or temperature-sensitive alleles of DRS2 and null alleles of three other potential APLT genes (DNF1, DNF2, and DNF3). Assay of these membranes indicated that Drs2p was required for the ATP-dependent translocation of NBD-PS, whereas no active translocation of NBD-PE or NBD-phosphatidylcholine was detected. The specificity of Drs2p for NBD-PS suggested that translocation of PS would be required for the function of Drs2p in protein transport from the TGN. However, cho1 yeast strains that are unable to synthesize PS do not phenocopy drs2 but instead transport proteins normally via the secretory pathway. In addition, a drs2 cho1 double mutant retains drs2 transport defects. Therefore, whereas NBD-PS is a preferred substrate for Drs2p in vitro, endogenous PS is not an obligatory substrate in vivo for the role Drs2p plays in protein transport.
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Affiliation(s)
- Paramasivam Natarajan
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634, USA
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22
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Abstract
Inter- and intramembrane phospholipid transport processes are central features of membrane biogenesis and homeostasis. Relatively recent successes in the molecular genetic analysis of aminoglycerophospholipid transport processes in both yeast and mammalian cells are now providing important new information defining specific protein and lipid components that participate in these reactions. Studies focused on phosphatidylserine (PtdSer) transport to the mitochondria reveal that the process is regulated by ubiquitination. In addition, a specific mutation disrupts PtdSer transport between mitochondrial membranes. Analysis of PtdSer transport from the endoplasmic reticulum to the locus of PtdSer decarboxylase 2 demonstrates the requirement for a phosphatidylinositol-4-kinase, a phosphatidylinositol-binding protein, and the C2 domain of the decarboxylase. Examination of NBD-phosphatidylcholine transport demonstrates the involvement of the prevacuolar compartment and a requirement for multiple genes involved in regulating vacuolar protein sorting for transport of the lipid to the vacuole. In intramembrane transport, multiple genes are now identified including those encoding multidrug resistant protein family members, DNF family members, ATP binding cassette transporters, and pleiotropic drug resistance family members. The scramblase family constitutes a collection of putative transmembrane transporters that function in an ATP-independent manner. The genetic analysis of lipid traffic is uncovering new molecules involved in all aspects of the regulation and execution of the transport steps and also providing essential tools to critically test the involvement of numerous candidate molecules.Key words: lipid transport, lipid sorting, membrane biogenesis, organelles, flippase.
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Affiliation(s)
- Dennis R Voelker
- Department of Medicine, National Jewish Medical and Research Center, Denver, CO 80206, USA.
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23
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Abstract
High-risk pregnancy is the most common clinical association with antiphospholipid antibodies; the principal manifestations are pregnancy loss and early preeclampsia. Membership in this family of antibodies is continually growing and includes antibodies against a variety of phospholipids, phospholipid-protein complexes, and phospholipid-binding proteins. The current information in the literature is inadequate to clearly implicate a subgroup of antiphospholipid antibodies or a particular pathophysiologic mechanism as being responsible for poor pregnancy outcomes. It is clear, however, that prevalent diagnostic tests for LA and aCL are extremely useful to identify many of these patients, but are inadequate for diagnosis of all patients with autoimmune pregnancy loss or to elucidate the pathophysiology. Many patients who present clinically with autoimmune-like pregnancy complications currently are negative in tests for LA or aCL, but have antibodies against annexin V, phosphatidylserine, or other relevant antigens. The greatest risk for a complicated pregnancy is conveyed by a subgroup of antibodies that affect the normal function of placental trophoblast. As clinical laboratory tests designed to detect more members of the antiphospholipid antibody family become available, understanding of this complicated disease (APS) will increase.
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Affiliation(s)
- Neal S Rote
- Department of Reproductive Biology, Case Western Reserve University School of Medicine, 2500 MetroHealth Drive, Cleveland, OH 44109, USA.
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24
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Abstract
Lipids in biological membranes are asymmetrically distributed across the bilayer; the amine-containing phospholipids are enriched on the cytoplasmic surface of the plasma membrane, while the choline-containing and sphingolipids are enriched on the outer surface. The maintenance of transbilayer lipid asymmetry is essential for normal membrane function, and disruption of this asymmetry is associated with cell activation or pathologic conditions. Lipid asymmetry is generated primarily by selective synthesis of lipids on one side of the membrane. Because passive lipid transbilayer diffusion is slow, a number of proteins have evolved to either dissipate or maintain this lipid gradient. These proteins fall into three classes: 1) cytofacially-directed, ATP-dependent transporters ("flippases"); 2) exofacially-directed, ATP-dependent transporters ("floppases"); and 3) bidirectional, ATP-independent transporters ("scramblases"). The flippase is highly selective for phosphatidylserine and functions to keep this lipid sequestered from the cell surface. Floppase activity has been associated with the ABC class of transmembrane transporters. Although they are primarily nonspecific, at least two members of this class display selectivity for their substrate lipid. Scramblases are inherently nonspecific and function to randomize the distribution of newly synthesized lipids in the endoplasmic reticulum or plasma membrane lipids in activated cells. It is the combined action of these proteins and the physical properties of the membrane bilayer that generate and maintain transbilayer lipid asymmetry.
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Affiliation(s)
- David L Daleke
- Medical Sciences Program, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Bloomington, IN 47405, USA.
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25
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Williamson P, Schlegel RA. Transbilayer phospholipid movement and the clearance of apoptotic cells. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1585:53-63. [PMID: 12531537 DOI: 10.1016/s1388-1981(02)00324-4] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
When lymphocytes (and other cells) die by apoptosis, they orchestrate their own orderly removal by macrophages, and thereby prevent the inflammation that would otherwise attend cell lysis. As part of their demise, apoptotic cells disrupt the normal asymmetric distribution of phospholipids across their plasma membranes, an asymmetry normally maintained by an aminophospholipid translocase. This disruption of asymmetry, mediated by an activity known as the scramblase, generates ligands on the cell surface that trigger phagocytosis of the dying cell before lysis can occur. This crucial alteration of the plasma membrane is not dependent on caspase-mediated proteolysis, but quite unexpectedly, it is required both on the apoptotic target cell and on the phagocyte that engulfs it. At least in the phagocyte, this rearrangement may depend on the activity of an ABC ATPase, termed ABC1 in mammals and ced-7 in C. elegans.
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26
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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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27
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Affiliation(s)
- Peter J Quinn
- Division of Life Sciences, King's College London, 150 Stamford Street, London SE1 9NN, UK
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28
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Nakatsuka S, Hayashi M, Muroyama A, Otsuka M, Kozaki S, Yamada H, Moriyama Y. D-Aspartate is stored in secretory granules and released through a Ca(2+)-dependent pathway in a subset of rat pheochromocytoma PC12 cells. J Biol Chem 2001; 276:26589-96. [PMID: 11333256 DOI: 10.1074/jbc.m011754200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
D-Aspartate in mammalian neuronal and neuroendocrine cells is suggested to play a regulatory role(s) in the neuroendocrine function. Although D-aspartate is known to be released from neuroendocrine cells, the mechanism underlying the release is less understood. Rat pheochromocytoma PC12 cells contain an appreciable amount of D-aspartate (257 +/- 31 pmol/10(7) cells). Indirect immunofluorescence microscopy with specific antibodies against d-aspartate indicated that the amino acid is present within a particulate structure, which is co-localized with dopamine and chromogranin A, markers for secretory granules, but not with synaptophysin, a marker for synaptic-like microvesicles. After sucrose density gradient centrifugation of the postnuclear particulate fraction, about 80% of the d-aspartate was recovered in the secretory granule fraction. Upon the addition of KCl, an appreciable amount of D-aspartate (about 40 pmol/10(7) cells at 10 min) was released from cultured cells on incubation in the presence of Ca(2+) in the medium. The addition of also triggered d-aspartate release. Botulinum neurotoxin type E inhibited about 40% of KCl- and Ca(2+)-dependent d-aspartate release followed by specific cleavage of 25-kDa synaptosomal-associated protein. alpha-Latrotoxin increased the intracellular [Ca(2+)] and caused the Ca(2+)-dependent d-aspartate release. Bafilomycin A1 dissipated the intracellular acidic regions and inhibited 40% of the Ca(2+)-dependent D-aspartate release. These properties are similar to those of the exocytosis of dopamine. Furthermore, digitonin-permeabilized cells took up radiolabeled d-aspartate depending on MgATP, which is sensitive to bafilomycin A1 or 3,5-di-tert-butyl-4-hydroxybenzylidene-malononitrile. Taken together, these results strongly suggest that d-aspartate is stored in secretory granules and then secreted through a Ca(2+)-dependent exocytotic mechanism. Exocytosis of D-aspartate further supports the role(s) of D-aspartate as a chemical transmitter in neuroendocrine cells.
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Affiliation(s)
- S Nakatsuka
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
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29
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Schlegel RA, Williamson P. Phosphatidylserine, a death knell. Cell Death Differ 2001; 8:551-63. [PMID: 11536005 DOI: 10.1038/sj.cdd.4400817] [Citation(s) in RCA: 259] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2000] [Revised: 11/13/2000] [Accepted: 11/27/2000] [Indexed: 11/09/2022] Open
Abstract
Virtually every cell in the body restricts phosphatidylserine (PS) to the inner leaflet of the plasma membrane by energy-dependent transport from the outer to the inner leaflet of the bilayer. Apoptotic cells of all types rapidly randomize the asymmetric distribution, bringing PS to the surface where it serves as a signal for phagocytosis. A myriad of phagocyte receptors have been implicated in the recognition of apoptotic cells, among them a PS receptor, yet few ligands other than PS have been identified on the apoptotic cell surface. Since apoptosis and the associated exposure of PS on the cell surface is probably over 600 million years old, it is not surprising that evolution has appropriated aspects of this process for specialized purposes such as blood coagulation, membrane fusion and erythrocyte differentiation. Failure to efficiently remove apoptotic cells may contribute to inflammatory responses and autoimmune diseases resulting from chronic, inappropriate exposure of PS.
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Affiliation(s)
- R A Schlegel
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA 16802, USA
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30
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Yamada H, Otsuka M, Hayashi M, Nakatsuka S, Hamaguchi K, Yamamoto A, Moriyama Y. Ca2+-dependent exocytosis of L-glutamate by alphaTC6, clonal mouse pancreatic alpha-cells. Diabetes 2001; 50:1012-20. [PMID: 11334403 DOI: 10.2337/diabetes.50.5.1012] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Pancreatic islet cells express receptors and transporters for L-glutamate and are thus believed to use L-glutamate as an intercellular signaling molecule. However, the mechanism by which L-glutamate appears in the islets is unknown. In the present study, we investigated whether L-glutamate is secreted through exocytosis by alphaTC6 cells (clonal mouse pancreatic alpha-cells). An appreciable amount of L-glutamate was released from cultured cells after the addition of KCl or A23187 in the presence of Ca2+ and 10 mmol/l glucose in the medium. The KCl-induced glutamate release was significantly reduced when assayed in the absence of Ca2+ or when the cells were pretreated with EGTA-AM. The KCl-induced Ca2+-dependent glutamate release was inhibited approximately 40% by voltage-gated Ca2+ channel blockers, such as nifedipine at 20 micromol/l. The degree of KCl-induced Ca2+-dependent glutamate release was correlated with an increase in intracellular [Ca2+], as monitored by fura-2 fluorescence. Botulinum neurotoxin type E inhibited 55% of the KCl-induced Ca2+-dependent glutamate release, followed by specific cleavage of 25 kDa synaptosomal-associated protein. Furthermore, bafilomycin A1, a specific inhibitor of vacuolar H+-ATPase, inhibited 40% of the KCl-induced Ca2+-dependent glutamate release. Immunoelectronmicroscopy with antibodies against synaptophysin, a marker for neuronal synaptic vesicles and endocrine synaptic-like microvesicles, revealed a large number of synaptophysin-positive clear vesicles in cells. Digitonin-permeabilized cells took up L-glutamate only in the presence of MgATP, which is sensitive to bafilomycin A1 or 3,5-di-tert-butyl-4-hydroxybenzylidene-malononitrile (a proton conductor) but insensitive to either oligomycin or vanadate. From these results, it was concluded that alphaTC6 cells accumulate L-glutamate in the synaptophysin-containing vesicles in an ATP-dependent manner and secrete it through a Ca2+-dependent exocytic mechanism. The Ca2+-dependent glutamate release was also triggered when cells were transferred in the medium containing 1 mmol/l glucose, suggesting that low glucose treatment stimulates the release of glutamate. Our results are consistent with the idea that L-glutamate is secreted by alpha-cells through Ca2+-dependent regulated exocytosis.
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Affiliation(s)
- H Yamada
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Okayama University, Japan
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31
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Ding J, Wu Z, Crider BP, Ma Y, Li X, Slaughter C, Gong L, Xie XS. Identification and functional expression of four isoforms of ATPase II, the putative aminophospholipid translocase. Effect of isoform variation on the ATPase activity and phospholipid specificity. J Biol Chem 2000; 275:23378-86. [PMID: 10801890 DOI: 10.1074/jbc.m910319199] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
ATPase II, a vanadate-sensitive and phosphatidylserine-dependent Mg(2+)-ATPase, is a member of a subfamily of P-type ATPase and is presumably responsible for aminophospholipid translocation activity in eukaryotic cells. The aminophospholipid translocation activity plays an important physiological role in the maintenance of membrane phospholipid asymmetry that is observed in the plasma membrane as well as the membranes of certain cellular organelles. While the preparations of ATPase II from different sources share common fundamental properties, such as substrate specificity, inhibitor spectrum, and phospholipid dependence, they are divergent in several characteristics. These include specific ATPase activity and phospholipid selectivity. We report here the identification of four isoforms of ATPase II in bovine brain. These isoforms are formed by a combination of two major variations in their primary sequences and show that the structural variation of these isoforms has functional significance in both ATPase activity and phosholipid selectivity. Furthermore, studies with the phosphoenzyme intermediate of ATPase II and its recombinant isoforms revealed that phosphatidylserine is essential for the dephosphorylation of the intermediate. Without phosphatidylserine, ATPase II would be accumulated as phosphoenzyme in the presence of ATP, resulting in the interruption of its catalytic cycle.
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Affiliation(s)
- J Ding
- Division of Molecular Transport, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9121, USA
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32
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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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33
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Mouro I, Halleck MS, Schlegel RA, Mattei MG, Williamson P, Zachowski A, Devaux P, Cartron JP, Colin Y. Cloning, expression, and chromosomal mapping of a human ATPase II gene, member of the third subfamily of P-type ATPases and orthologous to the presumed bovine and murine aminophospholipid translocase. Biochem Biophys Res Commun 1999; 257:333-9. [PMID: 10198212 DOI: 10.1006/bbrc.1999.0347] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recently, a P-type ATPase was cloned from bovine chromaffin granules (b-ATPase II) and a mouse teratocarcinoma cell line (m-ATPase II) and was shown to be homologous to the Saccharomyces cerevisiae DRS2 gene, the inactivation of which resulted in defective transport of phosphatidylserine. Here, we report the cloning from a human skeletal muscle cDNA library of a human ATPase II (h-ATPase II), orthologous to the presumed bovine and mouse aminophospholipid translocase (95.3 and 95.9% amino acid identity, respectively). Compared with the bovine and mouse counterparts, the cloned h-ATPase II polypeptide exhibits a similar membrane topology, but contains 15 additional amino acids (1163 vs 1148) located in the second intracytoplasmic loop, near the DKTGTLT-phosphorylation site. However, RT-PCR analysis performed with RNA from different human tissues and cell lines revealed that the coding sequence for these 15 residues is sometimes present and sometimes absent, most likely as a result of a tissue-specific alternative splicing event. The h-ATPase II gene, which was mapped to chromosome 4p14-p12, is expressed as a 9.5-kb RNA species in a large variety of tissues, but was not detected in liver, testis, and placenta, nor in the erythroleukemic cell line K562.
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Affiliation(s)
- I Mouro
- INSERM U76, Institut National de la Transfusion Sanguine, Paris, France.
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Obringer AR, Dean KW, Channel SR, Rote NS. Aminophospholipid translocase activity in JEG-3; a choriocarcinoma model of cytotrophoblast differentiation. Placenta 1997; 18:421-6. [PMID: 9250704 DOI: 10.1016/s0143-4004(97)80042-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The plasma membrane is characterized by a non-symmetrical distribution of phospholipids; the outer monolayer of the plasma membrane consists primarily of phosphatidylcholine (PC), and the aminophospholipids, phosphatidylserine (PS) and phosphatidylethanolamine (PE), preferentially reside in the inner monolayer. Asymmetry is maintained by a membrane associated ATP-dependent aminophospholipid translocase that preferentially relocates PS and PE from the outer to the inner monolayer. Although in most cells the translocase minimizes expression of PS on the outer surface, differentiating trophoblasts express increasing levels of surface PS. One possible explanation of prolonged PS externalization is that trophoblasts lack an effective aminophospholipid translocase. To test this hypothesis, fluorescent PC and PS analogues, NBD-PC and NBD-PS, were introduced into the plasma membrane of a choriocarcinoma model of trophoblast, JEG-3 cells. After incubation, the fluorescent lipid remaining on the outer monolayer was removed by incubation with fetal bovine serum. JEG-3 cells selectively translocated 80 per cent of the NBD-PS without significant translocation of NBD-PC. The process was significantly inhibited by N-ethylmaleimide (NEM) and vanadate. It is concluded that this model of trophoblast contains an active aminophospholipid translocase.
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Affiliation(s)
- A R Obringer
- Department of Microbiology and Immunology, Wright State University School of Medicine, Dayton, OH 45435, USA
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35
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Suzuki H, Kamakura M, Morii M, Takeguchi N. The phospholipid flippase activity of gastric vesicles. J Biol Chem 1997; 272:10429-34. [PMID: 9099684 DOI: 10.1074/jbc.272.16.10429] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We found that isolated gastric vesicles contain a novel Mg2+-ATP-dependent phospholipid translocation (flippase) activity. Fluorescence analogue of phosphatidylcholine, 2-(12-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino)dodecanoyl-1-hexadecanoyl-sn-glycero-3- phosphocholine, was ATP-dependently translocated from the outer (cytosolic) to inner (luminal) leaflet of the lipid membrane bilayer of hog gastric vesicles. The translocation was saturable and depended on time and the ATP concentration (Km = 3.1 microM). The basal Mg2+-ATPase activity of gastric vesicles in the absence of K+ showed high (Km = 1.6 microM) and low (Km = 80 microM) affinities for ATP, indicating that the present flippase activity is driven mostly by the high affinity Mg2+-ATPase activity. It required Mg2+ but not K+. Verapamil, which is an inhibitor of mouse mdr2 phosphatidylcholine flippase, did not inhibit the present flippase activity. Isolated sarcoplasmic reticulum vesicles that contain Ca2+-ATPase did not show any flippase activity. Fluorescence analogues of phosphatidylserine and phosphatidylethanolamine were similarly translocated by the gastric flippase. These phospholipid flippase activities were inhibited by 2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine-3-acetonitrile (SCH 28080) (IC50 = 0.14-0.25 microM), a specific K+-ATPase inhibitor of gastric H+,K+-ATPase rich in gastric vesicles. IC50 value for the SCH 28080-inhibitable Mg2+-ATPase activity was about 0.13 microM, indicating that the phospholipid translocation was driven mostly by the SCH 28080-sensitive Mg2+-ATPase activity. Possible physiological roles of flippases were discussed in relation with the gastric acid secretory and cytoprotective mechanisms.
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Affiliation(s)
- H Suzuki
- Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-01, Japan
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36
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Yamada H, Yamamoto A, Takahashi M, Michibata H, Kumon H, Moriyama Y. The L-type Ca2+ channel is involved in microvesicle-mediated glutamate exocytosis from rat pinealocytes. J Pineal Res 1996; 21:165-74. [PMID: 8981261 DOI: 10.1111/j.1600-079x.1996.tb00284.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pinealocytes, parenchymal cells of the pineal gland, secrete glutamate through microvesicle-mediated exocytosis upon depolarization by KCl in the presence of Ca2+, which is involved in a novel paracrine-like intercellular signal transduction mechanism in neuroendocrine organs. In the present study, we investigated whether or not the L-type Ca2+ channel is involved in the microvesicle-mediated glutamate secretion from cultured rat pinealocytes. Nifedipine, a specific antagonist of the L-type Ca2+ channel, inhibited the Ca(2+)-dependent glutamate exocytosis by 48% at 20 microM. Other L-type Ca2+ channel antagonists, such as nitrendipine, showed similar effects. 1,4-Dihydro-2,6-dimethyl-5-nitro-4 [2-(trifluoromethyl)-phenyl]-3-pyridinecarboxylic acid methyl ester (BAY K8644), an agonist of the L-type Ca2+ channel, at 1 microM, on the other hand, stimulated the glutamate exocytosis about 1.6-fold. Consistently, these Ca2+ channel antagonists inhibited about 50% of the Ca2+ uptake, whereas BAY K8644 increased the uptake 5.3-fold. An antibody against the carboxyl-terminal region of the rabbit L-type Ca2+ channel recognized polypeptides of pinealocytes with apparent molecular masses of 250 and 270 kDa, respectively, and immunostained the plasma membrane region of the pinealocytes. These results strongly suggested that the entry of Ca2+ through L-type Ca2+ channel(s), at least in part, triggers microvesicle-mediated glutamate exocytosis in pinealocytes.
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Affiliation(s)
- H Yamada
- Division Marine Molecular Biology, Graduate School of Science, Hiroshima University, Japan
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37
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Webster LC, Apps DK. Analysis of nucleotide binding by a vacuolar proton-translocating adenosine triphosphatase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 240:156-64. [PMID: 8797849 DOI: 10.1111/j.1432-1033.1996.0156h.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The vacuolar-type proton-translocatine adenosine triphosphatase from bovine adrenal secretory granules (chromaffin granules) was purified and reconstituted into proteoliposomes. The binding of nucleotides to the enzyme was studied by quantifying their effects on the rate of inactivation by N-ethylmaleimide (MalNEt) of ATP-dependent proton translocation, and by direct measurement of the binding of [3H]MgADP. The results of these experiments are consistent with a model of the enzyme that had been developed as a result of kinetic experiments, the features of which are that the enzyme exists in two states, each containing three nucleotide-binding sites on catalytic subunits, and that nucleoside diphosphates regulate the enzyme by binding with high affinity to a single site in the inactive T state of the enzyme. Under the conditions of the experiments, MalNEt inactivated the ATPase in a pseudo-first order reaction. Rate constants of inactivation were reduced in the presence of MgADP, MgIDP and free ADP; the kinetics of protection suggested that the two conformational states of the enzyme were inactivated at different rates and also confirmed the existence of two different types of binding site for MgADP. Low nucleotide concentrations afforded partial protection from MalNEt; this was ascribed to binding of nucleotide to the regulatory site causing a shift in the conformational equilibrium towards the T state, which was more slowly inactivated than the unliganded R state of the enzyme. At higher nucleotide concentrations, binding at the catalytic site afforded complete protection from MalNEt. Protection by MgADP[S] and magnesium 2'- and 3'-O-[4-benzoylbenzoyl]adenosine 5'-triphosphate showed simpler kinetics but was also consistent with previously reported kinetic results. Analysis of subunit labelling with [3H]MalNEt showed that the three 72-kDa (catalytic) subunits were alkylated by MalNEt with similar rate constants, consistent with a symmetrical arrangement of the catalytic subunits, in contrast to the situation in F-type ATPases. Analysis of the binding of [3H]MgADP also confirmed the results of kinetic experiments. MgADP was shown to bind to the enzyme with an apparent dissociation constant of about 66 nM; assuming that the nucleotide binds only to the T-state, the true dissociation constant is < 1 nM. Using Blue Native polyacrylamide gel electrophoresis to separate the holo-ATPase from the membrane sector, the stoichiometry of binding was calculated to be 0.6 mol/mol enzyme, confirming the existence of a single regulatory site for MgADP. However, binding of MgADP to the enzyme was much slower than could be accounted for by the measured dissociation constants, suggesting that it is rate limited by a step such as a protein conformational change. Treatment designed to remove endogenous nucleotide had no effect on the rate or extent of binding of MgADP.
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Affiliation(s)
- L C Webster
- Department of Biochemistry, University of Edinburgh, Scotland
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38
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Pacheco G, Lippo de Bécemberg I, Gonzalez de Alfonzo R, Alfonzo MJ. Biochemical characterization of a V-ATPase of tracheal smooth muscle plasma membrane fraction. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1282:182-92. [PMID: 8703972 DOI: 10.1016/0005-2736(96)00038-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A biochemical characterization of a Mg(2+)-ATPase activity associated with a plasma membrane fraction isolated from airway (tracheal) smooth muscle was performed. This enzyme is an integral part of the membrane remaining tightly bound after 0.6 M KCl extraction. This enzyme activity showed a cold inactivation in the presence of ATP and Mg2+. Also, this Mg(2+)-ATPase was stimulated by monovalent anions being Cl-, the best anion for such stimulation, even though Br- and I- were good substitutes and F- was ineffective. This Cl--stimulated activity showed a powerful nucleosidetriphosphatase activity having the following divalent cation specificity: Mg2+ > Mn2+ > Ca2+, where Zn2+ and Fe2+ were ineffective. This ATPase activity was not inhibited by ouabain oligomycin C and vanadate indicating that neither P- or F-ATPases were associated with this enzyme activity. However, the existence of a V-ATPase was shown by the significant inhibition causes by bafilomycin A1. Additionally, this V-ATPase seems to be coupled to Cl- conductor because duramycin inhibited this ATPase activity. The presence of a H+ pump associated to this V-ATPase was shown indirectly, through the stimulatory effect produced by uncouplers such as FCCP and 1799, which were able to produce significant stimulation of this V-ATPase indicating the existence of a H(+)-ATPase. Finally, the immunodetection of a 72 kDa polypeptide using a specific antibody against the A subunit (72 kDa) of V-ATPase from chromaffin granule demonstrated the presence of a V-ATPase in this plasma membrane fraction.
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Affiliation(s)
- G Pacheco
- Catedras de Bioquímica y Patología General y Fisiopatología, Universidad Central de Venezuela, Caracas, Venezuela
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39
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Tang X, Halleck MS, Schlegel RA, Williamson P. A subfamily of P-type ATPases with aminophospholipid transporting activity. Science 1996; 272:1495-7. [PMID: 8633245 DOI: 10.1126/science.272.5267.1495] [Citation(s) in RCA: 352] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The appearance of phosphatidylserine on the surface of animal cells triggers phagocytosis and blood coagulation. Normally, phosphatidylserine is confined to the inner leaflet of the plasma membrane by an aminophospholipid translocase, which has now been cloned and sequenced. The bovine enzyme is a member of a previously unrecognized subfamily of P-type adenosine triphosphatases (ATPases) that may have diverged from the primordial enzyme before the separation of the known families of ion-translocating ATPases. Studies in Saccharomyces cerevisiae suggest that aminophospholipid translocation is a general function of members of this family.
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Affiliation(s)
- X Tang
- Department of Biology, Amherst College, MA 01002, USA
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40
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Moriyama Y, Yamamoto A. Vesicular L-glutamate transporter in microvesicles from bovine pineal glands. Driving force, mechanism of chloride anion activation, and substrate specificity. J Biol Chem 1995; 270:22314-20. [PMID: 7673214 DOI: 10.1074/jbc.270.38.22314] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Pinealocytes, endocrine cells that synthesize and secrete melatonin, possess a large number of synaptic-like microvesicles (MVs) containing the L-glutamate transporter (Moriyama, Y., and Yamamoto, A. (1995) FEBS Lett., 367, 233-236). In this study, the L-glutamate transporter in MVs isolated from bovine pineal glands was characterized as to its driving force, requirement of anions, and substrate specificity. Upon the addition of ATP, the MVs accumulated L-glutamate. The uptake was significantly dependent on the extravesicular Cl- concentration, being negligible in the absence of Cl- and maximum at 2-5 mM and decreasing gradually at 20-100 mM. The membrane potential (inside positive) was maximum at 0-10 mM Cl- and then decreased gradually depending on the Cl- concentration, whereas a pH gradient was practically absent without Cl- and increased gradually up to 100 mM Cl-. Ammonium acetate or nigericin plus K+, a dissipator of a pH gradient, had little effect on or was slightly stimulatory toward the uptake, whereas valinomycin plus K+ inhibited both formation of the membrane potential and the glutamate uptake to similar extents. The ATP- and Cl(-)-dependent glutamate uptake was inhibited by fluoride, iodide, or thiocyanate, without vacuolar H(+)-ATPase being affected. An anion channel blocker, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, similarly inhibited the glutamate uptake in a Cl- protectable manner. Furthermore, ATP- and glutamate-dependent acidification of MVs was observed when 4 mM Cl- was present. Among more than 50 kinds of glutamate analogues tested, only a few compounds, including 1-aminocyclohexane-trans-1,3-dicarboxylic acid, caused similar acidification. A good correlation was observed between the acidification and the inhibition of glutamate uptake by glutamate analogues. These results indicated that 1) the major driving force of the glutamate uptake is the membrane potential, 2) Cl- regulates the glutamate uptake, probably via anion-binding site(s) on the transporter, and 3) the transporter shows strict substrate specificity. Hence, the overall properties of the vesicular glutamate transporter in the MVs well matched those of the synaptic vesicle glutamate transporter. We concluded that the vesicular glutamate transporter, being similar if not identical to the neuronal counterpart, operates in endocrine cells.
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Affiliation(s)
- Y Moriyama
- Graduate Department of Gene Sciences, Faculty of Sciences, Hiroshima University, Japan
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41
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Webster LC, Perez-Castineira JR, Atkins GL, Apps DK. Allosteric Regulation of Proton Translocation by a Vacuolar Adenosinetriphosphatase. ACTA ACUST UNITED AC 1995. [DOI: 10.1111/j.1432-1033.1995.586zz.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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42
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Yu H, Ferrier J. Osteoclast ATP receptor activation leads to a transient decrease in intracellular pH. J Cell Sci 1995; 108 ( Pt 9):3051-8. [PMID: 8537444 DOI: 10.1242/jcs.108.9.3051] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Application of extracellular adenosine triphosphate (ATP) induces a pulsed decrease in osteoclast intracellular pH (pHi), as measured with seminaphthofluorescein (SNAFL)-calcein on a laser scanning confocal microscope. Adenosine diphosphate also produces a pHi decrease, but adenosine monophosphate, uridine triphosphate, 2-methylthio-ATP, and beta, gamma-methylene-ATP have little effect on pHi. The ATP-induced pHi decrease is largely inhibited by suramin, a P2 purinergic receptor blocker. Clamping intracellular free [Ca2+] ([Ca2+]i) with BAPTA/AM does not affect the ATP-induced pHi change, showing that this pHi decrease is not caused by the increased intracellular [Ca2+]i that is produced by activation of osteoclast purinergic receptors. We show that an increase in [Ca2+]i by itself will produce a pHi increase. The ATP effect is not blocked by inhibition of Na+/H+ exchange by either Na(+)-free bathing medium or amiloride. Two inhibitors of the osteoclast cell membrane proton pump, N-ethylmaleimide and vanadate, produce partial inhibition of the ATP-induced pHi decrease. Two other proton pump inhibitors, bafilomycin and N,N'-dicyclohexylcarbodiimide, have no influence on the ATP effect. None of the proton pump inhibitors but vanadate has a direct effect on pHi. Vanadate produces a transient pHi increase upon application to the bathing medium, possibly as a result of its known effect of stimulating the Na+/H+ exchanger. Inhibition of Cl-/HCO3- exchange by decreasing extracellular Cl- gives a pronounced long-term pHi increase, supporting the hypothesis that this exchange has an important role in osteoclast pHi homeostasis. In Cl(-)-free extracellular medium, there is a greatly reduced effect of extracellular ATP on pHi.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H Yu
- Medical Research Council Group in Periodontal Physiology, University of Toronto, Ontario, Canada
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43
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Williamson P, Bevers EM, Smeets EF, Comfurius P, Schlegel RA, Zwaal RF. Continuous analysis of the mechanism of activated transbilayer lipid movement in platelets. Biochemistry 1995; 34:10448-55. [PMID: 7654698 DOI: 10.1021/bi00033a017] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Dithionite reduction of fluorescent (NBD) phospholipids was used as the basis of a continuous assay of transbilayer lipid movement to the cell surface during platelet activation. This assay reveals that virtually all previously internalized phosphatidylserine passes through the external leaflet of the membrane within 90 s after activation with Ca2+ and ionophore or with thrombin and thapsigargin. We demonstrate that this lipid scrambling is reversible, bidirectional, and insensitive to the lipid headgroup. Prolonged activation gradually results in inactivation of the scramblase. The assay also reveals that activation of the scrambling activity is sensitive to the sulfhydryl reagent pyridyldithioethylamine, suggesting the involvement of a protein in the process of activated transbilayer lipid scrambling.
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Affiliation(s)
- P Williamson
- Department of Biology, Amherst College, Massachusetts 01002, USA
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44
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Moriyama Y, Yamamoto A, Yamada H, Tashiro Y, Tomochika K, Takahashi M, Maeda M, Futai M. Microvesicles isolated from bovine posterior pituitary accumulate norepinephrine. J Biol Chem 1995; 270:11424-9. [PMID: 7744779 DOI: 10.1074/jbc.270.19.11424] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Histochemical study indicated that the posterior pituitary possesses numerous microvesicles (MVs) containing synaptophysin, a marker protein specific for brain synaptic vesicles (Navone, F., Di Gioia, G., Jahn, R., Browning, M., Greengard, P., and De Camilli, P. (1989) J. Cell Biol. 109, 3425-2433). By monitoring cross-reactivity with anti-synaptophysin antibody, the MVs were highly purified from bovine posterior pituitaries by a combination of differential and sucrose density gradient centrifugations. The purified MVs had an average diameter of about 60 nm and were associated with synaptophysin as revealed by immunoelectron microscopy. The vesicles contained ATPase activity partially sensitive to bafilomycin A1 and to vanadate. The membrane fraction immunoisolated with anti-synaptophysin antibody also exhibited similar ATPase activity. The two ATPases could be purified separately; the vandate-sensitive enzyme was identified as a 115-kDa polypeptide immunochemically similar to chromaffin granule P-ATPase (forming phosphoenzyme intermediate), and the bafilomycin A1-sensitive ATPase showed essentially the same properties as those of vacuolar type H(+)-ATPases. Upon addition of ATP, the MVs formed an electrochemical gradient of protons and took up norepinephrine in a reserpine-sensitive manner, indicating the presence of secondary monoamine transporter coupled with vacuolar type H(+)-ATPase. No uptake of L-glutamate, gamma-aminobutyrate, glycine, or acetylcholine was observed. The identification of MVs as organelles responsible for storage of monoamines is important for understanding the physiological function of the posterior pituitary.
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Affiliation(s)
- Y Moriyama
- Department of Biochemistry and Organic Chemistry, Osaka University
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45
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Moriyama Y, Patel V, Futai M. Quinacrine mustard and lipophilic cations inhibitory to both vacuolar H(+)-ATPase and F0F1-ATP synthase. FEBS Lett 1995; 359:69-72. [PMID: 7851533 DOI: 10.1016/0014-5793(95)00013-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Various lipophilic cations, such as quinacrine mustard and dequalinium, which are known to inhibit mitochondrial F1-ATPase, strongly inhibited vacuolar H(+)-ATPase purified from bovine adrenal chromaffin granules. Quinacrine mustard bound irreversibly to vacuolar H(+)-ATPase subunit A, and the 115 kDa accessory polypeptide and dithiothreitol had no effect. The binding was competitively inhibited by chlorpromazine and quinacrine, and these compounds specifically reduced the amount of labeling of subunit A. Quinacrine mustard also prevented the binding of [alpha-32P]ATP to subunit A but had no effect on the binding of [3H]N-ethylmaleimide to either subunit A or the 115 kDa accessory polypeptide. These results suggest that the binding site of quinacrine mustard in subunit A is not related to the N-ethylmaleimide-binding site(s), which is important for activity.
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Affiliation(s)
- Y Moriyama
- Department of Biochemistry and Organic Chemistry, Osaka University, Japan
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46
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Williamson P, Schlegel RA. Back and forth: the regulation and function of transbilayer phospholipid movement in eukaryotic cells. Mol Membr Biol 1994; 11:199-216. [PMID: 7711830 DOI: 10.3109/09687689409160430] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
That some membranes restrict certain lipid species to one side of the bilayer and others to the opposite side has been known for two decades. However, how this asymmetric transbilayer distribution is generated and controlled, how many and what type of membranes are so structured, and even the reason for its existence is just now beginning to be understood. It has been a decade since the discovery of an activity which transports in an ATP-dependent manner only the aminophospholipids from the outer to the inner leaflet of the plasma membrane. This aminophospholipid translocase has yet to be isolated, reconstituted, and identified molecularly. Elevating intracellular Ca2+ allows all the major classes of phospholipids to move freely across the bilayer, scrambling lipids and dissipating asymmetry. The nature of this pathway and its mode of activation by Ca2+ remain to be determined. Though loss of transbilayer asymmetry by blood cells clearly produces a procoagulant surface and increases interactions with the reticuloendothelial system, it remains to be elucidated whether maintenance of blood homeostasis is just one expression of a more general raison d'être for lipid asymmetry. It is these persisting uncertainties and gaps in our knowledge which make the field such an interesting and exciting challenge at the present time.
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Affiliation(s)
- P Williamson
- Department of Biology, Amherst College, MA 01002
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47
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Uyama T, Moriyama Y, Futai M, Michibata H. Immunological detection of a vacuolar-type H(+)-ATPase in vanadocytes of the ascidian Ascidia sydneiensis samea. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1994; 270:148-54. [PMID: 7964552 DOI: 10.1002/jez.1402700204] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Ascidians belonging to the family Ascidiidae are known to accumulate vanadium from seawater in their blood cells, concentrating vanadium by a factor of 10(7). Among several different types of blood cell, the signet ring cells have both high levels of vanadium and a low pH. These observations suggest the possibility that proton ions concentrated by a H(+)-ATPase are energetically linked to the accumulation of vanadium. In the present experiments, therefore, we made an immunological search for a H(+)-ATPase in the vacuolar membranes of the signet ring cells, as a first step in our attempts to clarify the energetics of the accumulation of vanadium by these cells. Antibodies raised against the 72-kDa and 57-kDa subunits of a vacuolar-type H(+)-ATPase from bovine chromaffin granules reacted with the vacuolar membranes of signet ring cells. Immunoblotting analysis confirmed that specific antigens in ascidian blood cells actually reacted with the antibodies. Furthermore, addition of bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase, inhibited the uptake of protons by the vacuoles of signet ring cells. Thus, the addition of bafilomycin A1 inhibited the pumping function of the vacuoles of signet ring cells, with resultant neutralization of the contents of the vacuoles.
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Affiliation(s)
- T Uyama
- Mukaishima Marine Biological Laboratory, Faculty of Science, Hiroshima University, Japan
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48
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Abstract
VAT-1 is an abundant protein in Torpedo electric organ which copurifies with a major ATPase activity from synaptic vesicles. VAT-1 was expressed in E. coli and the product was purified and analyzed. The protein binds specifically to an ATP column and displays an ATPase activity as measured by the kinetics of [32P]phosphate release. The activity is dependent on divalent ions, with both Mg2+ and Ca2+ supporting the reaction. The apparent Km for ATP is 18 microM. This ATPase activity is not affected by known inhibitors of the vesicular V- and P-type ATPases such as vanadate and N-ethylmaleimide. We suggest that VAT-1 activity may affect ATP-dependent reactions in Torpedo nerve terminals, such as phosphorylation and dephosphorylation of proteins.
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Affiliation(s)
- M Linial
- Department of Biological Chemistry, Hebrew University, Jerusalem, Israel
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49
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Rhoads AR, Vu ND, Carroll AG. Small membrane-associated GTP-binding proteins of catecholamine-secreting cells. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1993; 25:79-86. [PMID: 8432385 DOI: 10.1016/0020-711x(93)90492-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
1. Four GTP-binding proteins (23-27 kDa) were identified in membranes from PC12 cells by [alpha 32P]GTP binding to nitrocellulose blots of SDS-polyacrylamide gels. 2. The GTP-binding proteins remained associated with membranes during stimulation of intact cells by K(+)-depolarization or even after addition of Ca2+ to digitonin-permeabilized cells. 3. By two-dimensional gel electrophoresis, six GTP-binding proteins were resolved and based on their mobility, their phosphorylation state appeared independent of Ca2+. 4. Fractionation of PC12 membranes showed that these GTP-binding proteins were broadly distributed in post-nuclear membranes with the plasma membranes containing the highest specific GTP-binding activity. 5. Membrane fractions from bovine adrenal medulla contain similar GTP-binding proteins with GTP-binding intensity also being highest in the plasma membrane. 6. The GTP-binding proteins could be concentrated in the detergent-rich fraction upon Triton X-114 phase separation.
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Affiliation(s)
- A R Rhoads
- Department of Biochemistry and Molecular Biology, Howard University, College of Medicine, Washington, D.C. 20059
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50
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Parsons SM, Prior C, Marshall IG. Acetylcholine transport, storage, and release. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1993; 35:279-390. [PMID: 8463062 DOI: 10.1016/s0074-7742(08)60572-3] [Citation(s) in RCA: 163] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
ACh is released from cholinergic nerve terminals under both resting and stimulated conditions. Stimulated release is mediated by exocytosis of synaptic vesicle contents. The structure and function of cholinergic vesicles are becoming known. The concentration of ACh in vesicles is about 100-fold greater than the concentration in the cytoplasm. The AChT exhibits the lowest binding specificity among known ACh-binding proteins. It is driven by efflux of protons pumped into the vesicle by the V-type ATPase. A potent pharmacology of the AChT based on the allosteric VR has been developed. It has promise for clinical applications that include in vivo evaluation of the density of cholinergic innervation in organs based on PET and SPECT. The microscopic kinetics model that has been developed and the very low transport specificity of the vesicular AChT-VR suggest that the transporter has a channel-like or multidrug resistance protein-like structure. The AChT-VR has been shown to be tightly associated with proteoglycan, which is an unexpected macromolecular relationship. Vesamicol and its analogs block evoked release of ACh from cholinergic nerve terminals after a lag period that depends on the rate of release. Recycling quanta of ACh that are sensitive to vesamicol have been identified electrophysiologically, and they constitute a functional correlate of the biochemically identified VP2 synaptic vesicles. The concept of transmitter mobilization, including the observation that the most recently synthesized ACh is the first to be released, has been greatly clarified because of the availability of vesamicol. Differences among different cholinergic nerve terminal types in the sensitivity to vesamicol, the relative amounts of readily and less releasable ACh, and other aspects of the intracellular metabolism of ACh probably are more apparent than real. They easily could arise from differences in the relative rates of competing or sequential steps in the complicated intraterminal metabolism of ACh rather than from fundamental differences among the terminals. Nonquantal release of ACh from motor nerve terminals arises at least in part from the movement of cytoplasmic ACh through the AChT located in the cytoplasmic membrane, and it is blocked by vesamicol. Possibly, the proteoglycan component of the AChT-VR produces long-term residence of the macromolecular complex in the cytoplasmic membrane through interaction with the synaptic matrix. The preponderance of evidence suggests that a significant fraction of what previously, heretofore, had been considered to be nonquantal release from the motor neuron actually is quantal release from the neuron at sites not detected electrophysiologically.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- S M Parsons
- Department of Chemistry, University of California, Santa Barbara 93106
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