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Norris AC, Mansueto AJ, Jimenez M, Yazlovitskaya EM, Jain BK, Graham TR. Flipping the script: Advances in understanding how and why P4-ATPases flip lipid across membranes. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119700. [PMID: 38382846 DOI: 10.1016/j.bbamcr.2024.119700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 11/15/2023] [Accepted: 02/16/2024] [Indexed: 02/23/2024]
Abstract
Type IV P-type ATPases (P4-ATPases) are a family of transmembrane enzymes that translocate lipid substrates from the outer to the inner leaflet of biological membranes and thus create an asymmetrical distribution of lipids within membranes. On the cellular level, this asymmetry is essential for maintaining the integrity and functionality of biological membranes, creating platforms for signaling events and facilitating vesicular trafficking. On the organismal level, this asymmetry has been shown to be important in maintaining blood homeostasis, liver metabolism, neural development, and the immune response. Indeed, dysregulation of P4-ATPases has been linked to several diseases; including anemia, cholestasis, neurological disease, and several cancers. This review will discuss the evolutionary transition of P4-ATPases from cation pumps to lipid flippases, the new lipid substrates that have been discovered, the significant advances that have been achieved in recent years regarding the structural mechanisms underlying the recognition and flipping of specific lipids across biological membranes, and the consequences of P4-ATPase dysfunction on cellular and physiological functions. Additionally, we emphasize the requirement for additional research to comprehensively understand the involvement of flippases in cellular physiology and disease and to explore their potential as targets for therapeutics in treating a variety of illnesses. The discussion in this review will primarily focus on the budding yeast, C. elegans, and mammalian P4-ATPases.
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Affiliation(s)
- Adriana C Norris
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | | | - Mariana Jimenez
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | | | - Bhawik K Jain
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Todd R Graham
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
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2
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Sokolova D, Childs T, Hong S. Insight into the role of phosphatidylserine in complement-mediated synapse loss in Alzheimer's disease. Fac Rev 2021; 10:19. [PMID: 33718936 PMCID: PMC7946395 DOI: 10.12703/r/10-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The innate immune system plays an integral role in the brain. Synaptic pruning, a fundamental process in developmental circuit refinement, is partially mediated by neuroimmune signalling at the synapse. In particular, microglia, the major tissue-resident macrophages of the brain, and the classical complement cascade, an innate immune pathway that aids in the clearance of unwanted material, have been implicated in mediating synapse elimination. Emerging data suggest that improper signalling of the innate immune pathway at the synapse leads to pathological synapse loss in age-related neurodegenerative diseases, including Alzheimer's disease. Now the key questions are whether synapses are targeted by complement and, if so, which synapses are vulnerable to elimination. Here, we review recent work implicating C1q, the initiator of the classical complement cascade, and surrounding glia as mediators of synapse loss. We examine how synapses could undergo apoptosis-like pathways in the Alzheimer brain, which may lead to the externalisation of phosphatidylserine on synapses. Finally, we discuss potential roles for microglia and astrocytes in this 'synaptic apoptosis'. Critical insight into neuroimmune regulatory pathways on synapses will be key to developing effective targets against pathological synapse loss in dementia.
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Affiliation(s)
- Dimitra Sokolova
- UK Dementia Research Institute, Institute of Neurology, University College London, Gower Street, London WC1E 6BT, UK
| | - Thomas Childs
- UK Dementia Research Institute, Institute of Neurology, University College London, Gower Street, London WC1E 6BT, UK
| | - Soyon Hong
- UK Dementia Research Institute, Institute of Neurology, University College London, Gower Street, London WC1E 6BT, UK
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3
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Li T, Chiou B, Gilman CK, Luo R, Koshi T, Yu D, Oak HC, Giera S, Johnson‐Venkatesh E, Muthukumar AK, Stevens B, Umemori H, Piao X. A splicing isoform of GPR56 mediates microglial synaptic refinement via phosphatidylserine binding. EMBO J 2020; 39:e104136. [PMID: 32452062 PMCID: PMC7429740 DOI: 10.15252/embj.2019104136] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 04/20/2020] [Accepted: 04/22/2020] [Indexed: 12/31/2022] Open
Abstract
Developmental synaptic remodeling is important for the formation of precise neural circuitry, and its disruption has been linked to neurodevelopmental disorders such as autism and schizophrenia. Microglia prune synapses, but integration of this synapse pruning with overlapping and concurrent neurodevelopmental processes, remains elusive. Adhesion G protein-coupled receptor ADGRG1/GPR56 controls multiple aspects of brain development in a cell type-specific manner: In neural progenitor cells, GPR56 regulates cortical lamination, whereas in oligodendrocyte progenitor cells, GPR56 controls developmental myelination and myelin repair. Here, we show that microglial GPR56 maintains appropriate synaptic numbers in several brain regions in a time- and circuit-dependent fashion. Phosphatidylserine (PS) on presynaptic elements binds GPR56 in a domain-specific manner, and microglia-specific deletion of Gpr56 leads to increased synapses as a result of reduced microglial engulfment of PS+ presynaptic inputs. Remarkably, a particular alternatively spliced isoform of GPR56 is selectively required for microglia-mediated synaptic pruning. Our present data provide a ligand- and isoform-specific mechanism underlying microglial GPR56-mediated synapse pruning in the context of complex neurodevelopmental processes.
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Affiliation(s)
- Tao Li
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell ResearchUniversity of California, San Francisco (UCSF)San FranciscoCAUSA
- Department of MedicineBoston Children's Hospital and Harvard Medical SchoolBostonMAUSA
| | - Brian Chiou
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell ResearchUniversity of California, San Francisco (UCSF)San FranciscoCAUSA
| | - Casey K Gilman
- Department of MedicineBoston Children's Hospital and Harvard Medical SchoolBostonMAUSA
| | - Rong Luo
- Department of MedicineBoston Children's Hospital and Harvard Medical SchoolBostonMAUSA
| | - Tatsuhiro Koshi
- Department of MedicineBoston Children's Hospital and Harvard Medical SchoolBostonMAUSA
| | - Diankun Yu
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell ResearchUniversity of California, San Francisco (UCSF)San FranciscoCAUSA
| | - Hayeon C Oak
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell ResearchUniversity of California, San Francisco (UCSF)San FranciscoCAUSA
| | - Stefanie Giera
- Department of MedicineBoston Children's Hospital and Harvard Medical SchoolBostonMAUSA
| | | | - Allie K Muthukumar
- F. M. Kirby Neurobiology CenterChildren's HospitalHarvard Medical SchoolBostonMAUSA
| | - Beth Stevens
- F. M. Kirby Neurobiology CenterChildren's HospitalHarvard Medical SchoolBostonMAUSA
- Howard Hughes Medical InstituteBoston Children's HospitalBostonMAUSA
| | - Hisashi Umemori
- F. M. Kirby Neurobiology CenterChildren's HospitalHarvard Medical SchoolBostonMAUSA
| | - Xianhua Piao
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell ResearchUniversity of California, San Francisco (UCSF)San FranciscoCAUSA
- Department of MedicineBoston Children's Hospital and Harvard Medical SchoolBostonMAUSA
- F. M. Kirby Neurobiology CenterChildren's HospitalHarvard Medical SchoolBostonMAUSA
- Weill Institute for NeuroscienceUniversity of California, San Francisco (UCSF)San FranciscoCAUSA
- Division of NeonatologyDepartment of PediatricsUniversity of California, San Francisco (UCSF)San FranciscoCAUSA
- Newborn Brain Research InstituteUniversity of California, San Francisco (UCSF)San FranciscoCAUSA
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4
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Nagata S, Sakuragi T, Segawa K. Flippase and scramblase for phosphatidylserine exposure. Curr Opin Immunol 2020; 62:31-38. [DOI: 10.1016/j.coi.2019.11.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 11/25/2019] [Indexed: 01/30/2023]
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5
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Carbone E, Borges R, Eiden LE, García AG, Hernández‐Cruz A. Chromaffin Cells of the Adrenal Medulla: Physiology, Pharmacology, and Disease. Compr Physiol 2019; 9:1443-1502. [DOI: 10.1002/cphy.c190003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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6
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An Electrophysiological Approach to Measure Changes in the Membrane Surface Potential in Real Time. Biophys J 2019; 118:813-825. [PMID: 31409481 PMCID: PMC7036697 DOI: 10.1016/j.bpj.2019.06.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/21/2019] [Accepted: 06/26/2019] [Indexed: 02/07/2023] Open
Abstract
Biological membranes carry fixed charges at their surfaces. These arise primarily from phospholipid headgroups. In addition, membrane proteins contribute to the surface potential with their charged residues. Membrane lipids are asymmetrically distributed. Because of this asymmetry, the net-negative charge at the inner leaflet exceeds that at the outer leaflet. Changes in surface potential are predicted to give rise to apparent changes in membrane capacitance. Here, we show that it is possible to detect changes in surface potential by an electrophysiological approach; the analysis of cellular currents relies on assuming that the electrical properties of a cell are faithfully described by a three-element circuit (i.e., the minimal equivalent circuit) comprised of two resistors and one capacitor. However, to account for changes in surface potential, it is necessary to add a battery to this circuit connected in series with the capacitor. This extended circuit model predicts that the current response to a square-wave voltage pulse harbors information, which allows for separating the changes in surface potential from a true capacitance change. We interrogated our model by investigating changes in the capacitance induced by ligand binding to the serotonin transporter and to the glycine transporters (GlyT1 and GlyT2). The experimental observations were consistent with the predictions of the extended circuit. We conclude that ligand-induced changes in surface potential (reflecting the binding event) and in true membrane capacitance (reflecting the concomitant conformational change) can be detected in real time even in instances in which they occur simultaneously.
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Liou AY, Molday LL, Wang J, Andersen JP, Molday RS. Identification and functional analyses of disease-associated P4-ATPase phospholipid flippase variants in red blood cells. J Biol Chem 2019; 294:6809-6821. [PMID: 30850395 DOI: 10.1074/jbc.ra118.007270] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/06/2019] [Indexed: 02/04/2023] Open
Abstract
ATP-dependent phospholipid flippase activity crucial for generating lipid asymmetry was first detected in red blood cell (RBC) membranes, but the P4-ATPases responsible have not been directly determined. Using affinity-based MS, we show that ATP11C is the only abundant P4-ATPase phospholipid flippase in human RBCs, whereas ATP11C and ATP8A1 are the major P4-ATPases in mouse RBCs. We also found that ATP11A and ATP11B are present at low levels. Mutations in the gene encoding ATP11C are responsible for blood and liver disorders, but the disease mechanisms are not known. Using heterologous expression, we show that the T415N substitution in the phosphorylation motif of ATP11C, responsible for congenital hemolytic anemia, reduces ATP11C expression, increases retention in the endoplasmic reticulum, and decreases ATPase activity by 61% relative to WT ATP11C. The I355K substitution in the transmembrane domain associated with cholestasis and anemia in mice was expressed at WT levels and trafficked to the plasma membrane but was devoid of activity. We conclude that the T415N variant causes significant protein misfolding, resulting in low protein expression, cellular mislocalization, and reduced functional activity. In contrast, the I355K variant folds and traffics normally but lacks key contacts required for activity. We propose that the loss in ATP11C phospholipid flippase activity coupled with phospholipid scramblase activity results in the exposure of phosphatidylserine on the surface of RBCs, decreasing RBC survival and resulting in anemia.
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Affiliation(s)
- Angela Y Liou
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - Laurie L Molday
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - Jiao Wang
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - Jens Peter Andersen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Building 1160, DK-8000 Aarhus C, Denmark
| | - Robert S Molday
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
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8
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Shin HW, Takatsu H. Substrates of P4‐ATPases: beyond aminophospholipids (phosphatidylserine and phosphatidylethanolamine). FASEB J 2018; 33:3087-3096. [DOI: 10.1096/fj.201801873r] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Hye-Won Shin
- Graduate School of Pharmaceutical SciencesKyoto University Kyoto Japan
| | - Hiroyuki Takatsu
- Graduate School of Pharmaceutical SciencesKyoto University Kyoto Japan
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9
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Burtscher V, Hotka M, Li Y, Freissmuth M, Sandtner W. A label-free approach to detect ligand binding to cell surface proteins in real time. eLife 2018; 7:e34944. [PMID: 29697048 PMCID: PMC5991833 DOI: 10.7554/elife.34944] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/25/2018] [Indexed: 01/01/2023] Open
Abstract
Electrophysiological recordings allow for monitoring the operation of proteins with high temporal resolution down to the single molecule level. This technique has been exploited to track either ion flow arising from channel opening or the synchronized movement of charged residues and/or ions within the membrane electric field. Here, we describe a novel type of current by using the serotonin transporter (SERT) as a model. We examined transient currents elicited on rapid application of specific SERT inhibitors. Our analysis shows that these currents originate from ligand binding and not from a long-range conformational change. The Gouy-Chapman model predicts that adsorption of charged ligands to surface proteins must produce displacement currents and related apparent changes in membrane capacitance. Here we verified these predictions with SERT. Our observations demonstrate that ligand binding to a protein can be monitored in real time and in a label-free manner by recording the membrane capacitance.
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Affiliation(s)
- Verena Burtscher
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug DevelopmentCenter of Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - Matej Hotka
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug DevelopmentCenter of Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - Yang Li
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug DevelopmentCenter of Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug DevelopmentCenter of Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - Walter Sandtner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug DevelopmentCenter of Physiology and Pharmacology, Medical University of ViennaViennaAustria
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10
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Hussain SS, Harris MT, Kreutzberger AJB, Inouye CM, Doyle CA, Castle AM, Arvan P, Castle JD. Control of insulin granule formation and function by the ABC transporters ABCG1 and ABCA1 and by oxysterol binding protein OSBP. Mol Biol Cell 2018. [PMID: 29540530 PMCID: PMC5935073 DOI: 10.1091/mbc.e17-08-0519] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In pancreatic β-cells, insulin granule membranes are enriched in cholesterol and are both recycled and newly generated. Cholesterol’s role in supporting granule membrane formation and function is poorly understood. ATP binding cassette transporters ABCG1 and ABCA1 regulate intracellular cholesterol and are important for insulin secretion. RNAi interference–induced depletion in cultured pancreatic β-cells shows that ABCG1 is needed to stabilize newly made insulin granules against lysosomal degradation; ABCA1 is also involved but to a lesser extent. Both transporters are also required for optimum glucose-stimulated insulin secretion, likely via complementary roles. Exogenous cholesterol addition rescues knockdown-induced granule loss (ABCG1) and reduced secretion (both transporters). Another cholesterol transport protein, oxysterol binding protein (OSBP), appears to act proximally as a source of endogenous cholesterol for granule formation. Its knockdown caused similar defective stability of young granules and glucose-stimulated insulin secretion, neither of which were rescued with exogenous cholesterol. Dual knockdowns of OSBP and ABC transporters support their serial function in supplying and concentrating cholesterol for granule formation. OSBP knockdown also decreased proinsulin synthesis consistent with a proximal endoplasmic reticulum defect. Thus, membrane cholesterol distribution contributes to insulin homeostasis at production, packaging, and export levels through the actions of OSBP and ABCs G1 and A1.
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Affiliation(s)
- Syed Saad Hussain
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Megan T Harris
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Alex J B Kreutzberger
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908.,Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Candice M Inouye
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Catherine A Doyle
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Anna M Castle
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Peter Arvan
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, MI 48105
| | - J David Castle
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908.,Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908
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11
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Structural basis for phospholipid scrambling in the TMEM16 family. Curr Opin Struct Biol 2016; 39:61-70. [PMID: 27295354 DOI: 10.1016/j.sbi.2016.05.020] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 04/28/2016] [Accepted: 05/30/2016] [Indexed: 11/21/2022]
Abstract
Upon activation, lipid scramblases dissipate the lipid asymmetry of membranes, in an ATP-independent manner, by catalyzing flip-flop of lipids between the leaflets. The molecular identities of these proteins long remained obscure, but in recent years the TMEM16 family of proteins has been found to constitute Ca2+-activated scramblases. Recently, the X-ray structure of a fungal TMEM16 homologue has provided insight into the architecture of this protein family and into potential scrambling mechanisms. The protein forms homodimers with each subunit containing a membrane-spanning hydrophilic cleft. This region is of sufficient size to harbor polar headgroups on their way across the membrane and thus may lower the energetic barrier for the diffusion of lipids between the two leaflets of the bilayer. A regulatory Ca2+ binding site located within the membrane adjacent to this hydrophobic cleft is responsible for activation by yet unknown mechanisms.
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12
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Jensen MS, Costa SR, Theorin L, Christensen JP, Pomorski TG, López-Marqués RL. Application of image cytometry to characterize heterologous lipid flippases in yeast. Cytometry A 2016; 89:673-80. [PMID: 27272389 DOI: 10.1002/cyto.a.22886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Lipid flippases are integral membrane proteins that play a central role in moving lipids across cellular membranes. Some of these transporters are ATPases that couple lipid translocation to ATP hydrolysis, whereas others function without any discernible metabolic energy input. A growing number of lipid flippases has been identified but key features of their activity remain to be elucidated. A well-established method to characterize ATP-driven flippases is based on their heterologous expression in yeast, followed by incubation of the cells with fluorescent lipids. Internalization of these probes is typically monitored by flow cytometry, a costly and maintenance-intensive method. Here, we have optimized a protocol to use an automated image-based cell counter to accurately measure lipid uptake by heterologous lipid flippases expressed in yeast. The method was validated by comparison with the classical flow cytometric evaluation of lipid-labeled cells. In addition, we demonstrated that expression of fluorescently tagged flippase complexes can be directly co-related with fluorescent lipid uptake using the image-based cell counter system. The method extends the number of techniques available for characterization of lipid flippase activity, and should be readily adaptable to analyze a variety of other transport systems in yeast, parasites, and mammalian cells. © 2016 International Society for Advancement of Cytometry.
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Affiliation(s)
- Maria S Jensen
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Sara R Costa
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Lisa Theorin
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | | | - Thomas Günther Pomorski
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
- Faculty of Chemistry and Biochemistry, Department of Molecular Biochemistry, Ruhr University Bochum, Universitätstrasse 150, Bochum, D-44780, Germany
| | - Rosa L López-Marqués
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
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13
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Bevers EM, Williamson PL. Getting to the Outer Leaflet: Physiology of Phosphatidylserine Exposure at the Plasma Membrane. Physiol Rev 2016; 96:605-45. [PMID: 26936867 DOI: 10.1152/physrev.00020.2015] [Citation(s) in RCA: 293] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Phosphatidylserine (PS) is a major component of membrane bilayers whose change in distribution between inner and outer leaflets is an important physiological signal. Normally, members of the type IV P-type ATPases spend metabolic energy to create an asymmetric distribution of phospholipids between the two leaflets, with PS confined to the cytoplasmic membrane leaflet. On occasion, membrane enzymes, known as scramblases, are activated to facilitate transbilayer migration of lipids, including PS. Recently, two proteins required for such randomization have been identified: TMEM16F, a scramblase regulated by elevated intracellular Ca(2+), and XKR8, a caspase-sensitive protein required for PS exposure in apoptotic cells. Once exposed at the cell surface, PS regulates biochemical reactions involved in blood coagulation, and bone mineralization, and also regulates a variety of cell-cell interactions. Exposed on the surface of apoptotic cells, PS controls their recognition and engulfment by other cells. This process is exploited by parasites to invade their host, and in specialized form is used to maintain photoreceptors in the eye and modify synaptic connections in the brain. This review discusses what is known about the mechanism of PS exposure at the surface of the plasma membrane of cells, how actors in the extracellular milieu sense surface exposed PS, and how this recognition is translated to downstream consequences of PS exposure.
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Affiliation(s)
- Edouard M Bevers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands; and Department of Biology, Amherst College, Amherst, Massachusetts
| | - Patrick L Williamson
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands; and Department of Biology, Amherst College, Amherst, Massachusetts
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14
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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: 300] [Impact Index Per Article: 37.5] [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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15
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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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16
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Segawa K, Kurata S, Nagata S. Human Type IV P-type ATPases That Work as Plasma Membrane Phospholipid Flippases and Their Regulation by Caspase and Calcium. J Biol Chem 2015; 291:762-72. [PMID: 26567335 DOI: 10.1074/jbc.m115.690727] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Indexed: 11/06/2022] Open
Abstract
In plasma membranes, flippases translocate aminophospholipids such as phosphatidylserine and phosphatidylethanolamine from the extracellular to the cytoplasmic leaflet. Mammalian ATP11C, a type IV P-type ATPase, acts as a flippase at the plasma membrane. Here, by expressing 12 human type IV P-type ATPases in ATP11C-deficient cells, we determined that ATP8A2 and ATP11A can also act as plasma membrane flippases. As with ATP11C, ATP8A2 and ATP11A localized to the plasma membrane in a CDC50A-dependent manner. ATP11A was cleaved by caspases during apoptosis, and a caspase-resistant ATP11A blocked apoptotic PtdSer exposure. In contrast, ATP8A2 was not cleaved by caspase, and cells expressing ATP8A2 did not expose PtdSer during apoptosis. Similarly, high Ca(2+) concentrations inhibited the ATP11A and ATP11C PtdSer flippase activity, but ATP8A2 flippase activity was relatively resistant to Ca(2+). ATP11A and ATP11C were ubiquitously expressed in human and mouse adult tissues. In contrast, ATP8A2 was expressed in specific tissues, such as the brain and testis. Thus, ATP8A2 may play a specific role in translocating PtdSer in these tissues.
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Affiliation(s)
- Katsumori Segawa
- From the Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Sachiko Kurata
- From the Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Shigekazu Nagata
- From the Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
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17
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Segawa K, Nagata S. An Apoptotic 'Eat Me' Signal: Phosphatidylserine Exposure. Trends Cell Biol 2015; 25:639-650. [PMID: 26437594 DOI: 10.1016/j.tcb.2015.08.003] [Citation(s) in RCA: 481] [Impact Index Per Article: 53.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/08/2015] [Accepted: 08/17/2015] [Indexed: 12/19/2022]
Abstract
Apoptosis and the clearance of apoptotic cells are essential processes in animal development and homeostasis. For apoptotic cells to be cleared, they must display an 'eat me' signal, most likely phosphatidylserine (PtdSer) exposure, which prompts phagocytes to engulf the cells. PtdSer, which is recognized by several different systems, is normally confined to the cytoplasmic leaflet of the plasma membrane by a 'flippase'; apoptosis activates a 'scramblase' that quickly exposes PtdSer on the cell surface. The molecules that flip and scramble phospholipids at the plasma membrane have recently been identified. Here we discuss recent findings regarding the molecular mechanisms of apoptotic PtdSer exposure and the clearance of apoptotic cells.
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Affiliation(s)
- Katsumori Segawa
- Laboratory of Biochemistry and Immunology, WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan
| | - Shigekazu Nagata
- Laboratory of Biochemistry and Immunology, WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan.
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18
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Ansari IUH, Longacre MJ, Paulusma CC, Stoker SW, Kendrick MA, MacDonald MJ. Characterization of P4 ATPase Phospholipid Translocases (Flippases) in Human and Rat Pancreatic Beta Cells: THEIR GENE SILENCING INHIBITS INSULIN SECRETION. J Biol Chem 2015; 290:23110-23. [PMID: 26240149 DOI: 10.1074/jbc.m115.655027] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Indexed: 01/08/2023] Open
Abstract
The negative charge of phosphatidylserine in lipid bilayers of secretory vesicles and plasma membranes couples the domains of positively charged amino acids of secretory vesicle SNARE proteins with similar domains of plasma membrane SNARE proteins enhancing fusion of the two membranes to promote exocytosis of the vesicle contents of secretory cells. Our recent study of insulin secretory granules (ISG) (MacDonald, M. J., Ade, L., Ntambi, J. M., Ansari, I. H., and Stoker, S. W. (2015) Characterization of phospholipids in insulin secretory granules in pancreatic beta cells and their changes with glucose stimulation. J. Biol. Chem. 290, 11075-11092) suggested that phosphatidylserine and other phospholipids, such as phosphatidylethanolamine, in ISG could play important roles in docking and fusion of ISG to the plasma membrane in the pancreatic beta cell during insulin exocytosis. P4 ATPase flippases translocate primarily phosphatidylserine and, to a lesser extent, phosphatidylethanolamine across the lipid bilayers of intracellular vesicles and plasma membranes to the cytosolic leaflets of these membranes. CDC50A is a protein that forms a heterodimer with P4 ATPases to enhance their translocase catalytic activity. We found that the predominant P4 ATPases in pure pancreatic beta cells and human and rat pancreatic islets were ATP8B1, ATP8B2, and ATP9A. ATP8B1 and CDC50A were highly concentrated in ISG. ATP9A was concentrated in plasma membrane. Gene silencing of individual P4 ATPases and CDC50A inhibited glucose-stimulated insulin release in pure beta cells and in human pancreatic islets. This is the first characterization of P4 ATPases in beta cells. The results support roles for P4 ATPases in translocating phosphatidylserine to the cytosolic leaflets of ISG and the plasma membrane to facilitate the docking and fusion of ISG to the plasma membrane during insulin exocytosis.
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Affiliation(s)
- Israr-ul H Ansari
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Melissa J Longacre
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Coen C Paulusma
- the Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, 1105 BK Amsterdam, The Netherlands
| | - Scott W Stoker
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Mindy A Kendrick
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Michael J MacDonald
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
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19
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Panatala R, Hennrich H, Holthuis JCM. Inner workings and biological impact of phospholipid flippases. J Cell Sci 2015; 128:2021-32. [PMID: 25918123 DOI: 10.1242/jcs.102715] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The plasma membrane, trans-Golgi network and endosomal system of eukaryotic cells are populated with flippases that hydrolyze ATP to help establish asymmetric phospholipid distributions across the bilayer. Upholding phospholipid asymmetry is vital to a host of cellular processes, including membrane homeostasis, vesicle biogenesis, cell signaling, morphogenesis and migration. Consequently, defining the identity of flippases and their biological impact has been the subject of intense investigations. Recent work has revealed a remarkable degree of kinship between flippases and cation pumps. In this Commentary, we review emerging insights into how flippases work, how their activity is controlled according to cellular demands, and how disrupting flippase activity causes system failure of membrane function, culminating in membrane trafficking defects, aberrant signaling and disease.
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Affiliation(s)
- Radhakrishnan Panatala
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands Molecular Cell Biology Division, University of Osnabrück, 49076 Osnabrück, Germany
| | - Hanka Hennrich
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands
| | - Joost C M Holthuis
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands Molecular Cell Biology Division, University of Osnabrück, 49076 Osnabrück, Germany
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20
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Lee S, Uchida Y, Wang J, Matsudaira T, Nakagawa T, Kishimoto T, Mukai K, Inaba T, Kobayashi T, Molday RS, Taguchi T, Arai H. Transport through recycling endosomes requires EHD1 recruitment by a phosphatidylserine translocase. EMBO J 2015; 34:669-88. [PMID: 25595798 PMCID: PMC4365035 DOI: 10.15252/embj.201489703] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
P4-ATPases translocate aminophospholipids, such as phosphatidylserine (PS), to the cytosolic leaflet of membranes. PS is highly enriched in recycling endosomes (REs) and is essential for endosomal membrane traffic. Here, we show that PS flipping by an RE-localized P4-ATPase is required for the recruitment of the membrane fission protein EHD1. Depletion of ATP8A1 impaired the asymmetric transbilayer distribution of PS in REs, dissociated EHD1 from REs, and generated aberrant endosomal tubules that appear resistant to fission. EHD1 did not show membrane localization in cells defective in PS synthesis. ATP8A2, a tissue-specific ATP8A1 paralogue, is associated with a neurodegenerative disease (CAMRQ). ATP8A2, but not the disease-causative ATP8A2 mutant, rescued the endosomal defects in ATP8A1-depleted cells. Primary neurons from Atp8a2-/- mice showed a reduced level of transferrin receptors at the cell surface compared to Atp8a2+/+ mice. These findings demonstrate the role of P4-ATPase in membrane fission and give insight into the molecular basis of CAMRQ.
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Affiliation(s)
- Shoken Lee
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
| | - Yasunori Uchida
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
| | - Jiao Wang
- Departments of Biochemistry and Molecular Biology and Ophthalmology and Visual Sciences, Centre for Macular Research University of British Columbia, Vancouver, BC, Canada
| | - Tatsuyuki Matsudaira
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
| | - Takatoshi Nakagawa
- Department of Pharmacology, Osaka Medical College, Takatsuki-city Osaka, Japan
| | | | - Kojiro Mukai
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan Lipid Biology Laboratory, RIKEN, Wako-shi Saitama, Japan
| | - Takehiko Inaba
- Lipid Biology Laboratory, RIKEN, Wako-shi Saitama, Japan
| | | | - Robert S Molday
- Departments of Biochemistry and Molecular Biology and Ophthalmology and Visual Sciences, Centre for Macular Research University of British Columbia, Vancouver, BC, Canada
| | - Tomohiko Taguchi
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan Pathological Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
| | - Hiroyuki Arai
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan Pathological Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
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21
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Gómez-Lázaro M, Rinn C, Aroso M, Amado F, Schrader M. Proteomic analysis of zymogen granules. Expert Rev Proteomics 2014; 7:735-47. [DOI: 10.1586/epr.10.31] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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22
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Kato U, Inadome H, Yamamoto M, Emoto K, Kobayashi T, Umeda M. Role for phospholipid flippase complex of ATP8A1 and CDC50A proteins in cell migration. J Biol Chem 2012; 288:4922-34. [PMID: 23269685 DOI: 10.1074/jbc.m112.402701] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Type IV P-type ATPases (P4-ATPases) and CDC50 family proteins form a putative phospholipid flippase complex that mediates the translocation of aminophospholipids such as phosphatidylserine (PS) and phosphatidylethanolamine (PE) from the outer to inner leaflets of the plasma membrane. In Chinese hamster ovary (CHO) cells, at least eight members of P4-ATPases were identified, but only a single CDC50 family protein, CDC50A, was expressed. We demonstrated that CDC50A associated with and recruited P4-ATPase ATP8A1 to the plasma membrane. Overexpression of CDC50A induced extensive cell spreading and greatly enhanced cell migration. Depletion of either CDC50A or ATP8A1 caused a severe defect in the formation of membrane ruffles, thereby inhibiting cell migration. Analyses of phospholipid translocation at the plasma membrane revealed that the depletion of CDC50A inhibited the inward translocation of both PS and PE, whereas the depletion of ATP8A1 inhibited the translocation of PE but not that of PS, suggesting that the inward translocation of cell-surface PE is involved in cell migration. This hypothesis was further examined by using a PE-binding peptide and a mutant cell line with defective PE synthesis; either cell-surface immobilization of PE by the PE-binding peptide or reduction in the cell-surface content of PE inhibited the formation of membrane ruffles, causing a severe defect in cell migration. These results indicate that the phospholipid flippase complex of ATP8A1 and CDC50A plays a major role in cell migration and suggest that the flippase-mediated translocation of PE at the plasma membrane is involved in the formation of membrane ruffles to promote cell migration.
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Affiliation(s)
- Utako Kato
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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23
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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: 102] [Impact Index Per Article: 8.5] [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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24
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Outside of the box: recent news about phospholipid translocation by P4 ATPases. J Chem Biol 2012; 5:131-6. [PMID: 23853670 DOI: 10.1007/s12154-012-0078-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 06/27/2012] [Indexed: 10/28/2022] Open
Abstract
The P4 subfamily of P-type ATPases includes phospholipid transporters. Moving such bulky amphipathic substrate molecules across the membrane poses unique mechanistic problems. Recently, three papers from three different laboratories have offered insights into some of these problems. One effect of these experiments will be to ignite a healthy debate about the path through the enzyme taken by the substrate. A second effect is to suggest a counterintuitive model for the critical substrate-binding site. By putting concrete hypotheses into play, these papers finally provide a foundation for investigations of mechanism for these proteins.
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25
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Shin HW, Takatsu H, Nakayama K. Mechanisms of membrane curvature generation in membrane traffic. MEMBRANES 2012; 2:118-33. [PMID: 24957965 PMCID: PMC4021884 DOI: 10.3390/membranes2010118] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Revised: 02/20/2012] [Accepted: 02/21/2012] [Indexed: 11/17/2022]
Abstract
During the vesicular trafficking process, cellular membranes undergo dynamic morphological changes, in particular at the vesicle generation and fusion steps. Changes in membrane shape are regulated by small GTPases, coat proteins and other accessory proteins, such as BAR domain-containing proteins. In addition, membrane deformation entails changes in the lipid composition as well as asymmetric distribution of lipids over the two leaflets of the membrane bilayer. Given that P4-ATPases, which catalyze unidirectional flipping of lipid molecules from the exoplasmic to the cytoplasmic leaflets of the bilayer, are crucial for the trafficking of proteins in the secretory and endocytic pathways, changes in the lipid composition are involved in the vesicular trafficking process. Membrane remodeling is under complex regulation that involves the composition and distribution of lipids as well as assembly of proteins.
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Affiliation(s)
- Hye-Won Shin
- Career-Path Promotion Unit for Young Life Scientists, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
| | - Hiroyuki Takatsu
- Career-Path Promotion Unit for Young Life Scientists, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
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26
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Identification of residues defining phospholipid flippase substrate specificity of type IV P-type ATPases. Proc Natl Acad Sci U S A 2012; 109:E290-8. [PMID: 22308393 DOI: 10.1073/pnas.1115725109] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Type IV P-type ATPases (P4-ATPases) catalyze translocation of phospholipid across a membrane to establish an asymmetric bilayer structure with phosphatidylserine (PS) and phosphatidylethanolamine (PE) restricted to the cytosolic leaflet. The mechanism for how P4-ATPases recognize and flip phospholipid is unknown, and is described as the "giant substrate problem" because the canonical substrate binding pockets of homologous cation pumps are too small to accommodate a bulky phospholipid. Here, we identify residues that confer differences in substrate specificity between Drs2 and Dnf1, Saccharomyces cerevisiae P4-ATPases that preferentially flip PS and phosphatidylcholine (PC), respectively. Transplanting transmembrane segments 3 and 4 (TM3-4) of Drs2 into Dnf1 alters the substrate preference of Dnf1 from PC to PS. Acquisition of the PS substrate maps to a Tyr618Phe substitution in TM4 of Dnf1, representing the loss of a single hydroxyl group. The reciprocal Phe511Tyr substitution in Drs2 specifically abrogates PS recognition by this flippase causing PS exposure on the outer leaflet of the plasma membrane without disrupting PE asymmetry. TM3 and the adjoining lumenal loop contribute residues important for Dnf1 PC preference, including Phe587. Modeling of residues involved in substrate selection suggests a novel P-type ATPase transport pathway at the protein/lipid interface and a potential solution to the giant substrate problem.
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27
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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: 173] [Impact Index Per Article: 13.3] [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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28
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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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29
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Abstract
P4 ATPases (subfamily IV P-type ATPases) form a specialized subfamily of P-type ATPases and have been implicated in phospholipid translocation from the exoplasmic to the cytoplasmic leaflet of biological membranes. Pivotal roles of P4 ATPases have been demonstrated in eukaryotes, ranging from yeast, fungi and plants to mice and humans. P4 ATPases might exert their cellular functions by combining enzymatic phospholipid translocation activity with an enzyme-independent action. The latter could be involved in the timely recruitment of proteins involved in cellular signalling, vesicle coat assembly and cytoskeleton regulation. In the present review, we outline the current knowledge of the biochemical and cellular functions of P4 ATPases in the eukaryotic membrane.
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30
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Bryde S, Hennrich H, Verhulst PM, Devaux PF, Lenoir G, Holthuis JCM. CDC50 proteins are critical components of the human class-1 P4-ATPase transport machinery. J Biol Chem 2010; 285:40562-72. [PMID: 20961850 DOI: 10.1074/jbc.m110.139543] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the P(4) subfamily of P-type ATPases catalyze phospholipid transport and create membrane lipid asymmetry in late secretory and endocytic compartments. P-type ATPases usually pump small cations and the transport mechanism involved appears conserved throughout the family. How this mechanism is adapted to flip phospholipids remains to be established. P(4)-ATPases form heteromeric complexes with CDC50 proteins. Dissociation of the yeast P(4)-ATPase Drs2p from its binding partner Cdc50p disrupts catalytic activity (Lenoir, G., Williamson, P., Puts, C. F., and Holthuis, J. C. (2009) J. Biol. Chem. 284, 17956-17967), suggesting that CDC50 subunits play an intimate role in the mechanism of transport by P(4)-ATPases. The human genome encodes 14 P(4)-ATPases while only three human CDC50 homologues have been identified. This implies that each human CDC50 protein interacts with multiple P(4)-ATPases or, alternatively, that some human P(4)-ATPases function without a CDC50 binding partner. Here we show that human CDC50 proteins each bind multiple class-1 P(4)-ATPases, and that in all cases examined, association with a CDC50 subunit is required for P(4)-ATPase export from the ER. Moreover, we find that phosphorylation of the catalytically important Asp residue in human P(4)-ATPases ATP8B1 and ATP8B2 is critically dependent on their CDC50 subunit. These results indicate that CDC50 proteins are integral part of the P(4)-ATPase flippase machinery.
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Affiliation(s)
- Susanne Bryde
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584CH Utrecht, The Netherlands
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31
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Leventis PA, Grinstein S. The distribution and function of phosphatidylserine in cellular membranes. Annu Rev Biophys 2010; 39:407-27. [PMID: 20192774 DOI: 10.1146/annurev.biophys.093008.131234] [Citation(s) in RCA: 705] [Impact Index Per Article: 50.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Phosphatidylserine (PS) is the most abundant negatively charged phospholipid in eukaryotic membranes. PS directs the binding of proteins that bear C2 or gamma-carboxyglutamic domains and contributes to the electrostatic association of polycationic ligands with cellular membranes. Rather than being evenly distributed, PS is found preferentially in the inner leaflet of the plasma membrane and in endocytic membranes. The loss of PS asymmetry is an early indicator of apoptosis and serves as a signal to initiate blood clotting. This review discusses the determinants and functional implications of the subcellular distribution and membrane topology of PS.
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Affiliation(s)
- Peter A Leventis
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.
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32
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Paulusma CC, Oude Elferink RP. P4 ATPases - The physiological relevance of lipid flipping transporters. FEBS Lett 2010; 584:2708-16. [DOI: 10.1016/j.febslet.2010.04.071] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 04/28/2010] [Accepted: 04/28/2010] [Indexed: 11/27/2022]
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33
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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: 151] [Impact Index Per Article: 10.1] [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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Reconstitution of phospholipid translocase activity with purified Drs2p, a type-IV P-type ATPase from budding yeast. Proc Natl Acad Sci U S A 2009; 106:16586-91. [PMID: 19805341 DOI: 10.1073/pnas.0904293106] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Type-IV P-type ATPases (P4-ATPases) are putative phospholipid translocases, or flippases, that translocate specific phospholipid substrates from the exofacial to the cytosolic leaflet of membranes to generate phospholipid asymmetry. In addition, the activity of Drs2p, a P4-ATPase from Saccharomyces cerevisiae, is required for vesicle-mediated protein transport from the Golgi and endosomes, suggesting a role for phospholipid translocation in vesicle budding. Drs2p is necessary for translocation of a fluorescent phosphatidylserine analogue across purified Golgi membranes. However, a flippase activity has not been reconstituted with purified Drs2p or any other P4-ATPase, so whether these ATPases directly pump phospholipid across the membrane bilayer is unknown. Here, we show that Drs2p can catalyze phospholipid translocation directly through purification and reconstitution of this P4-ATPase into proteoliposomes. The noncatalytic subunit, Cdc50p, also was reconstituted in the proteoliposome, although at a substoichiometric concentration relative to Drs2p. In proteoliposomes containing Drs2p, a phosphatidylserine analogue was actively flipped across the liposome bilayer to the outer leaflet in the presence of Mg(2+)-ATP, whereas no activity toward the phosphatidylcholine or sphingomyelin analogues was observed. This flippase activity was mediated by Drs2p, because protein-free liposomes or proteoliposomes reconstituted with a catalytically inactive form of Drs2p showed no translocation activity. These data demonstrate for the first time the reconstitution of a flippase activity with a purified P4-ATPase.
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35
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Holthuis JCM, van Meer G, Huitema K. Lipid microdomains, lipid translocation and the organization of intracellular membrane transport (Review). Mol Membr Biol 2009. [DOI: 10.1080/0988768031000100768] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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36
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Pohl A, López-Montero I, Pohl A, López-Montero I, Rouvière F, Giusti F, Devaux PF. Rapid transmembrane diffusion of ceramide and dihydroceramide spin-labelled analogues in the liquid ordered phase. Mol Membr Biol 2009; 26:194-204. [DOI: 10.1080/09687680902733815] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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37
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Riekhof WR, Voelker DR. The yeast plasma membrane P4-ATPases are major transporters for lysophospholipids. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:620-7. [PMID: 19268715 DOI: 10.1016/j.bbalip.2009.02.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 02/23/2009] [Accepted: 02/24/2009] [Indexed: 11/25/2022]
Abstract
The transbilayer movement of phospholipids plays an essential role in establishing and maintaining the asymmetric distribution of lipids in biological membranes. The P4-ATPase family has been implicated as the major transporters of the aminoglycerophospholipids in both surface and endomembrane systems. Historically, fluorescent lipid analogs have been used to monitor the lipid transport activity of the P4-ATPases. Recent evidence now demonstrates that lyso-phosphatidylethanolamine (lyso-PtdEtn) and lyso-phosphatidylcholine (lyso-PtdCho) are bona fide biological substrates transported by the yeast plasma membrane ATPases, Dnf1p and Dnf2p, in consort with a second protein Lem3p. Subsequent to transport, the lysophospholipids are acylated by the enzyme Ale1p to produce PtdEtn and PtdCho. The transport of the lysophospholipids occurs at rates sufficient to support all the PtdEtn and PtdCho synthesis required for rapid cell growth. The lysophospholipid transporters also utilize the anti-neoplastic and anti-parasitic ether lipid substrates related to edelfosine. The identification of biological substrates for the plasma membrane ATPases coupled with the power of yeast genetics now provides new tools to dissect the structure and function of the aminoglycerophospholipid transporters.
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Affiliation(s)
- Wayne R Riekhof
- Department of Medicine, National Jewish Health, 1400 Jackson St., Denver, CO 80206, USA
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38
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Folmer DE, Elferink RPJO, Paulusma CC. P4 ATPases - lipid flippases and their role in disease. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:628-35. [PMID: 19254779 DOI: 10.1016/j.bbalip.2009.02.008] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 02/12/2009] [Accepted: 02/12/2009] [Indexed: 12/11/2022]
Abstract
P4 ATPases (type 4 P-type ATPases) are multispan transmembrane proteins that have been implicated in phospholipid translocation from the exoplasmic to the cytoplasmic leaflet of biological membranes. Studies in Saccharomyces cerevisiae have indicated that P4 ATPases are important in vesicle biogenesis and are required for vesicular trafficking along several intracellular vesicular transport routes. Although little is known about mammalian P4 ATPases, some members of this subfamily appear to be associated with human disease or mouse pathophysiology. ATP8B1, a phosphatidylserine translocase, is the most extensively studied mammalian P4 ATPase. This protein is important for maintaining the detergent resistant properties of the apical membrane of the hepatocyte. Mutations in ATP8B1 give rise to severe liver disease. Furthermore, a role for Atp8b3 in mouse sperm cell capacitation has been suggested, whereas deficiency of Atp10a and Atp10d leads to insulin resistance and obesity in mice. Here we review the present status on the pathophysiological consequences of P4 ATPase deficiency.
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Affiliation(s)
- Dineke E Folmer
- AMC Liver Center, Academic Medical Center, University of Amsterdam, Meibergdreef 69-71, 1105BK Amsterdam, The Netherlands
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Puts CF, Holthuis JCM. Mechanism and significance of P4 ATPase-catalyzed lipid transport: lessons from a Na+/K+-pump. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:603-11. [PMID: 19233312 DOI: 10.1016/j.bbalip.2009.02.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 02/07/2009] [Accepted: 02/10/2009] [Indexed: 11/19/2022]
Abstract
Members of the P(4) subfamily of P-type ATPases are believed to catalyze phospholipid transport across membrane bilayers, a process influencing a host of cellular functions. Atomic structures and functional analysis of P-type ATPases that pump small cations and metal ions revealed a transport mechanism that appears to be conserved throughout the family. A challenging problem is to understand how this mechanism is adapted in P(4) ATPases to flip phospholipids. P(4) ATPases form oligomeric complexes with members of the CDC50 protein family. While formation of these complexes is required for P(4) ATPase export from the endoplasmic reticulum, little is known about the functional role of the CDC50 subunits. The Na(+)/K(+)-ATPase and closely-related H(+)/K(+)-ATPase are the only other P-type pumps that are oligomeric, comprising mandatory beta-subunits that are strikingly reminiscent of CDC50 proteins. Besides serving a role in the functional maturation of the catalytic alpha-subunit, the beta-subunit also contributes specifically to intrinsic transport properties of the Na(+)/K(+) pump. As beta-subunits and CDC50 proteins likely adopted similar structures to accomplish analogous tasks, current knowledge of the Na(+)/K(+)-ATPase provides a useful guide for understanding the inner workings of the P(4) ATPase class of lipid pumps.
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Affiliation(s)
- Catheleyne F Puts
- Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Padualaan 8, 3584 CH Utrecht, The Netherlands
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40
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How lipid flippases can modulate membrane structure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1591-600. [DOI: 10.1016/j.bbamem.2008.03.007] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 03/09/2008] [Accepted: 03/12/2008] [Indexed: 11/23/2022]
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41
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On the origin of lipid asymmetry: the flip side of ion transport. Curr Opin Chem Biol 2007; 11:654-61. [DOI: 10.1016/j.cbpa.2007.09.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Revised: 09/11/2007] [Accepted: 09/20/2007] [Indexed: 11/19/2022]
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42
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Spicer SS, Qu C, Smythe N, Schulte BA. Mitochondria-activated cisternae generate the cell specific vesicles in auditory hair cells. Hear Res 2007; 233:40-5. [PMID: 17825509 PMCID: PMC2888100 DOI: 10.1016/j.heares.2007.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 06/15/2007] [Accepted: 07/09/2007] [Indexed: 11/23/2022]
Abstract
A dense population of vesicles largely fills the infranuclear compartment of gerbil inner hair cells (IHCs). Although the nature of the cargo in these vesicles has not been determined, the absence of a Golgi apparatus from the IHC's basal compartment suggests that the vesicles lack the glycosylated protein that Golgi cisternae would provide. Instead, they likely possess neurotransmitter and function as synaptic vesicles. The morphologic mechanism for generating the vesicles also remains unexplained. Ultrastructural examination revealed a few discrete clusters of mitochondria in the IHC's basal compartment. The clustered mitochondria made contact either with intermingling single cisternae or with one end of an unique set of polarized parallel cisternae. Both of these cisternal forms belong to a novel, mitochondria-activated category of cisternae which transforms into aligned segments where contacting mitochondria. Mitochondria-activated cisternae also envelope the vesicles in Hensen bodies of outer hair cells (OHCs). Coexistence of the mitochondria-activated cisternae with a specialized population of cytoplasmic vesicles in both IHCs and OHCs implicated this type of cisterna in synthesis of the cell specific vesicles. Assumedly, the mitochondria-activated cisternae possess an ATPase of the Class IV type. This class of enzymes, also designated flippases, translocates aminophospholipid from the outer to inner leaflet of the lipid bilayer and appears thereby to induce a lipid asymmetry which leads to cisternal segmentation and then vesiculation. In support of such an interpretation, RT-PCR analysis demonstrated the presence of Class IV ATPase in the Organ of Corti.
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Affiliation(s)
- Samuel S Spicer
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, 165 Ashley Avenue, Suite 309, P.O. Box 250908, Charleston, SC 29425, USA.
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43
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Liu K, Hua Z, Nepute JA, Graham TR. Yeast P4-ATPases Drs2p and Dnf1p are essential cargos of the NPFXD/Sla1p endocytic pathway. Mol Biol Cell 2006; 18:487-500. [PMID: 17122361 PMCID: PMC1783782 DOI: 10.1091/mbc.e06-07-0592] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Drs2p family P-type ATPases (P4-ATPases) are required in multiple vesicle-mediated protein transport steps and are proposed to be phospholipid translocases (flippases). The P4-ATPases Drs2p and Dnf1p cycle between the exocytic and endocytic pathways, and here we define endocytosis signals required by these proteins to maintain a steady-state localization to internal organelles. Internalization of Dnf1p from the plasma membrane uses an NPFXD endocytosis signal and its recognition by Sla1p, part of an endocytic coat/adaptor complex with clathrin, Pan1p, Sla2p/End4p, and End3p. Drs2p has multiple endocytosis signals, including two NPFXDs near the C terminus and PEST-like sequences near the N terminus that may mediate ubiquitin (Ub)-dependent endocytosis. Drs2p localizes to the trans-Golgi network in wild-type cells and accumulates on the plasma membrane when both the Ub- and NPFXD-dependent endocytic mechanisms are inactivated. Surprisingly, the pan1-20 temperature-sensitive mutant is constitutively defective for Ub-dependent endocytosis but is not defective for NPFXD-dependent endocytosis at the permissive growth temperature. To sustain viability of pan1-20, Drs2p must be endocytosed through the NPFXD/Sla1p pathway. Thus, Drs2p is an essential endocytic cargo in cells compromised for Ub-dependent endocytosis. These results demonstrate an essential role for endocytosis in retrieving proteins back to the Golgi, and they define critical cargos of the NPFXD/Sla1p system.
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Affiliation(s)
- Ke Liu
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634
| | - Zhaolin Hua
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634
| | - Joshua A. Nepute
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634
| | - Todd R. Graham
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634
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Natarajan P, Graham TR. Measuring translocation of fluorescent lipid derivatives across yeast Golgi membranes. Methods 2006; 39:163-8. [PMID: 16828307 DOI: 10.1016/j.ymeth.2006.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Accepted: 05/01/2006] [Indexed: 10/24/2022] Open
Abstract
Phospholipid asymmetry is a fundamental feature of the plasma membrane of most eukaryotic cells and its regulation is linked to diverse physiological processes such as apoptosis and blood clotting [P. Williamson, R.A. Schlegel, Biochim. Biophys. Acta 1585 (2002) 53-63; R.F. Zwaal, A.J. Schroit, Blood 89 (1997) 1121-1132]. In addition, the phospholipid translocases (flippases) that are thought to establish asymmetry are also implicated in vesicle-mediated protein transport throughout the secretory and endocytic pathways [T.R. Graham, Trends Cell Biol. 14 (2004) 670-677]. However, the biochemical properties of phospholipid translocases in membranes of the Golgi complex and endosomes have received much less attention than translocases in the plasma membrane. We describe here a method for purifying yeast Golgi membranes and assaying an ATP-dependent phospholipid translocase activity in these membranes using fluorescent lipid analogues. This assay detects ATP-dependent translocation of labeled phosphatidylserine across late Golgi membranes, which requires the activity of a P-type ATPase called Drs2p [P. Natarajan, J. Wang, Z. Hua, T.R. Graham, Proc. Natl. Acad. Sci. USA 101 (2004) 10614-10619].
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45
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Chen S, Wang J, Muthusamy BP, Liu K, Zare S, Andersen RJ, Graham TR. Roles for the Drs2p-Cdc50p Complex in Protein Transport and Phosphatidylserine Asymmetry of the Yeast Plasma Membrane. Traffic 2006; 7:1503-17. [PMID: 16956384 DOI: 10.1111/j.1600-0854.2006.00485.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Drs2p, a P-type adenosine triphosphatase required for a phosphatidylserine (PS) flippase activity in the yeast trans Golgi network (TGN), was first implicated in protein trafficking by a screen for mutations synthetically lethal with arf1 (swa). Here, we show that SWA4 is allelic to CDC50, encoding a membrane protein previously shown to chaperone Drs2p from the endoplasmic reticulum to the Golgi complex. We find that cdc50Delta exhibits the same clathrin-deficient phenotypes as drs2Delta, including delayed transport of carboxypeptidase Y to the vacuole, mislocalization of resident TGN enzymes and the accumulation of aberrant membrane structures. These trafficking defects precede appearance of cell polarity defects in cdc50Delta, suggesting that the latter are a secondary consequence of disrupting Golgi function. Involvement of Drs2p-Cdc50p in PS translocation suggests a role in restricting PS to the cytosolic leaflet of the Golgi and plasma membrane. Annexin V binding and papuamide B hypersensitivity indicate that drs2Delta or cdc50Delta causes a loss of plasma membrane PS asymmetry. However, clathrin and other endocytosis null mutants also exhibit a comparable loss of PS asymmetry, and studies with drs2-ts and clathrin (chc1-ts) conditional mutants suggest that loss of plasma membrane asymmetry is a secondary consequence of disrupting protein trafficking.
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Affiliation(s)
- Sophie Chen
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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46
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Paulusma CC, Oude Elferink RPJ. Diseases of intramembranous lipid transport. FEBS Lett 2006; 580:5500-9. [PMID: 16828084 DOI: 10.1016/j.febslet.2006.06.067] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 06/19/2006] [Accepted: 06/20/2006] [Indexed: 12/20/2022]
Abstract
The maintenance of transbilayer distribution of phospholipids is crucial for proper cell function. Intramembrane transport of lipids is mediated by three activities termed floppases, flippases, and scramblases. Members of the ATP-binding cassette transporter family and P-type ATPase superfamily have been implicated in the translocation of lipids. The importance of these activities is exemplified by several severe human inherited disorders that are caused by defects in intramembranous transport of lipids. In order to elucidate the molecular mechanisms that underlie these disorders, the combination of in vivo, biochemical, and structural analyses on intramembrane transporters is crucial.
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Affiliation(s)
- Coen C Paulusma
- Amsterdam Liver Center, Department of Experimental Hepatology, Academic Medical Center, Meibergdreef 69-71, S-1-168, 1105 BK Amsterdam, The Netherlands.
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47
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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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48
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Alder-Baerens N, Lisman Q, Luong L, Pomorski T, Holthuis JCM. Loss of P4 ATPases Drs2p and Dnf3p disrupts aminophospholipid transport and asymmetry in yeast post-Golgi secretory vesicles. Mol Biol Cell 2006; 17:1632-42. [PMID: 16452632 PMCID: PMC1415292 DOI: 10.1091/mbc.e05-10-0912] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Eukaryotic plasma membranes generally display asymmetric lipid distributions with the aminophospholipids concentrated in the cytosolic leaflet. This arrangement is maintained by aminophospholipid translocases (APLTs) that use ATP hydrolysis to flip phosphatidylserine (PS) and phosphatidylethanolamine (PE) from the external to the cytosolic leaflet. The identity of APLTs has not been established, but prime candidates are members of the P4 subfamily of P-type ATPases. Removal of P4 ATPases Dnf1p and Dnf2p from budding yeast abolishes inward translocation of 6-[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)aminocaproyl] (NBD)-labeled PS, PE, and phosphatidylcholine (PC) across the plasma membrane and causes cell surface exposure of endogenous PE. Here, we show that yeast post-Golgi secretory vesicles (SVs) contain a translocase activity that flips NBD-PS, NBD-PE, and NBD-PC to the cytosolic leaflet. This activity is independent of Dnf1p and Dnf2p but requires two other P4 ATPases, Drs2p and Dnf3p, that reside primarily in the trans-Golgi network. Moreover, SVs have an asymmetric PE arrangement that is lost upon removal of Drs2p and Dnf3p. Our results indicate that aminophospholipid asymmetry is created when membrane flows through the Golgi and that P4-ATPases are essential for this process.
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Affiliation(s)
- Nele Alder-Baerens
- Institute of Biology and Biophysics, Humboldt University Berlin, 10115 Berlin, Germany
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49
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Kurz A, Viertel D, Herrmann A, Müller K. Localization of phosphatidylserine in boar sperm cell membranes during capacitation and acrosome reaction. Reproduction 2005; 130:615-26. [PMID: 16264092 DOI: 10.1530/rep.1.00561] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
One of the essential properties of mammalian, including sperm, plasma membranes is a stable transversal lipid asymmetry with the aminophospholipids, phosphatidylserine (PS) and phosphatidylethanolamine (PE), typically in the inner, cytoplasmic leaflet. The maintenance of this nonrandom lipid distribution is important for the homeostasis of the cell. To clarify the relevance of lipid asymmetry to sperm function, we have studied the localization of PS in boar sperm cell membranes. By using labeled annexin V as a marker for PS and propidium iodide (PI) as a stain for nonviable cells in conjunction with different methods (flow cytometry, fluorescence and electron microscopy), we have assessed the surface exposure of PS in viable cells during sperm genesis, that is, before and during capacitation as well as after acrosome reaction. An approach was set up to address also the presence of PS in the outer acrosome membrane. The results show that PS is localized in the cytoplasmic leaflet of the plasma membrane as well as on the outer acrosome membrane. Our results further indicate the cytoplasmic localization of PS in the postacrosomal region. During capacitation and acrosome reaction of spermatozoa, PS does not become exposed on the outer surface of the viable cells. Only in a subpopulation of PI-positive sperm cells does PS became accessible upon capacitation. The stable cytoplasmic localization of PS in the plasma membrane, as well as in the outer acrosome membrane, is assumed to be essential for a proper genesis of sperm cells during capacitation and acrosome reaction.
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Affiliation(s)
- Anke Kurz
- Humboldt-Universität zu Berlin, Institut für Biologie, Invalidenstrasse 42, D-10099 Berlin, Germany
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50
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Paulusma CC, Oude Elferink RPJ. The type 4 subfamily of P-type ATPases, putative aminophospholipid translocases with a role in human disease. Biochim Biophys Acta Mol Basis Dis 2005; 1741:11-24. [PMID: 15919184 DOI: 10.1016/j.bbadis.2005.04.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 04/21/2005] [Accepted: 04/25/2005] [Indexed: 11/22/2022]
Abstract
The maintenance of phospholipid asymmetry in membrane bilayers is a paradigm in cell biology. However, the mechanisms and proteins involved in phospholipid translocation are still poorly understood. Members of the type 4 subfamily of P-type ATPases have been implicated in the translocation of phospholipids from the outer to the inner leaflet of membrane bilayers. In humans, several inherited disorders have been identified which are associated with loci harboring type 4 P-type ATPase genes. Up to now, one inherited disorder, Byler disease or progressive familial intrahepatic cholestasis type 1 (PFIC1), has been directly linked to mutations in a type 4 P-type ATPase gene. How the absence of an aminophospholipid translocase activity relates to this severe disease is, however, still unclear. Studies in the yeast Saccharomyces cerevisiae have recently identified important roles for type 4 P-type ATPases in intracellular membrane- and protein-trafficking events. These processes require an (amino)phospholipid translocase activity to initiate budding or fusion of membrane vesicles from or with other membranes. The studies in yeast have greatly contributed to our cell biological insight in membrane dynamics and intracellular-trafficking events; if this knowledge can be translated to mammalian cells and organs, it will help to elucidate the molecular mechanisms which underlie severe inherited human diseases such as Byler disease.
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Affiliation(s)
- C C Paulusma
- Department of Experimental Hepatology, Academic Medical Center/AMC Liver Center, Meibergdreef 69-71, 1105 BK Amsterdam, The Netherlands.
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