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Šťastný D, Balleková A, Tahotná D, Pokorná L, Holič R, Humpolíčková J, Griač P. Characterization of two Plasmodium falciparum lipid transfer proteins of the Sec14/CRAL-TRIO family. Biochim Biophys Acta Mol Cell Biol Lipids 2025; 1870:159572. [PMID: 39426587 DOI: 10.1016/j.bbalip.2024.159572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2024] [Revised: 09/11/2024] [Accepted: 10/13/2024] [Indexed: 10/21/2024]
Abstract
Invasion of human red blood cells by the malaria parasite Plasmodium falciparum is followed by dramatic modifications of erythrocytes properties, including de novo formation of new membrane systems. Lipid transfer proteins from both the parasite and the host cell are most likely an important part of those membrane remodeling processes. Using bioinformatics and in silico structural analysis, we have identified five P. falciparum potential lipid transfer proteins containing cellular retinaldehyde binding - triple functional domain (CRAL-TRIO). Two of these proteins, C6KTD4, encoded by the PF3D7_0629900 gene and Q8II87, encoded by the PF3D7_1127600 gene, were studied in more detail. In vitro lipid transfer assays using recombinant C6KTD4 and Q8II87 confirmed that these proteins are indeed bona fide lipid transfer proteins. C6KTD4 transfers sterols, phosphatidylinositol 4,5 bisphosphate, and, to some degree, also phosphatidylcholine between two membrane compartments. Q8II87 possesses phosphatidylserine transfer activity in vitro. In the yeast model, the expression of P. falciparumQ8II87 protein partially complements the absence of Sec14p and its closest homologue, Sfh1p. C6KTD4 protein can substitute for the collective essential function of oxysterol-binding related proteins. According to published whole genome studies in P. falciparum, absence of C6KTD4 and Q8II87 proteins has severe consequences for parasite viability. Therefore, CRAL-TRIO lipid transfer proteins of P. falciparum are potential targets of novel antimalarials, in search for which the yeast model expressing these proteins could be a valuable tool.
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Affiliation(s)
- Dominik Šťastný
- Centre of Biosciences, Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovakia
| | - Alena Balleková
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10 Praha 6, Czech Republic
| | - Dana Tahotná
- Centre of Biosciences, Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovakia
| | - Lucia Pokorná
- Centre of Biosciences, Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovakia
| | - Roman Holič
- Centre of Biosciences, Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovakia
| | - Jana Humpolíčková
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10 Praha 6, Czech Republic
| | - Peter Griač
- Centre of Biosciences, Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovakia.
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Sebinelli HG, Syska C, Čopič A, Lenoir G. Established and emerging players in phospholipid scrambling: A structural perspective. Biochimie 2024; 227:111-122. [PMID: 39304020 DOI: 10.1016/j.biochi.2024.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 09/16/2024] [Accepted: 09/17/2024] [Indexed: 09/22/2024]
Abstract
The maintenance of a diverse and non-homogeneous lipid composition in cell membranes is crucial for a multitude of cellular processes. One important example is transbilayer lipid asymmetry, which refers to a difference in lipid composition between the two leaflets of a cellular membrane. Transbilayer asymmetry is especially pronounced at the plasma membrane, where at resting state, negatively-charged phospholipids such as phosphatidylserine (PS) are almost exclusively restricted to the cytosolic leaflet, whereas sphingolipids are mostly found in the exoplasmic leaflet. Transbilayer movement of lipids is inherently slow, and for a fast cellular response, for example during apoptosis, transmembrane proteins termed scramblases facilitate the movement of polar/charged lipid headgroups through the membrane interior. In recent years, an expanding number of proteins from diverse families have been suggested to possess a lipid scramblase activity. Members of TMEM16 and XKR proteins have been implicated in blood clotting and apoptosis, whereas the scrambling activity of ATG9 and TMEM41B/VMP1 proteins contributes to the synthesis of autophagosomal membrane during autophagy. Structural studies, in vitro reconstitution of lipid scrambling, and molecular dynamics simulations have significantly advanced our understanding of the molecular mechanisms of lipid scrambling and helped delineate potential lipid transport pathways through the membrane. A number of examples also suggest that lipid scrambling activity can be combined with another activity, as is the case for TMEM16 proteins, which also function as ion channels, rhodopsin in the photoreceptor membrane, and possibly other G-protein coupled receptors.
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Affiliation(s)
- Heitor Gobbi Sebinelli
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell, Gif-sur-Yvette, France
| | - Camille Syska
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293, Montpellier, Cedex 05, France
| | - Alenka Čopič
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293, Montpellier, Cedex 05, France
| | - Guillaume Lenoir
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell, Gif-sur-Yvette, France.
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Ballekova A, Eisenreichova A, Różycki B, Boura E, Humpolickova J. Coordination of transporter, cargo, and membrane properties during non-vesicular lipid transport. Commun Biol 2024; 7:1585. [PMID: 39604557 PMCID: PMC11603022 DOI: 10.1038/s42003-024-07301-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Accepted: 11/21/2024] [Indexed: 11/29/2024] Open
Abstract
Homeostasis of cellular membranes is maintained by fine-tuning their lipid composition. Yeast lipid transporter Osh6, belonging to the oxysterol-binding protein-related proteins family, was found to participate in the transport of phosphatidylserine (PS). PS synthesized in the endoplasmic reticulum is delivered to the plasma membrane, where it is exchanged for phosphatidylinositol 4-phosphate (PI4P). PI4P provides the driving force for the directed PS transport against its concentration gradient. In this study, we employed an in vitro approach to reconstitute the transport process into the minimalistic system of large unilamellar vesicles to reveal its fundamental biophysical determinants. Our study draws a comprehensive portrait of the interplay between the structure and dynamics of Osh6, the carried cargo lipid, and the physical properties of the involved membranes, with particular attention to the presence of charged lipids and to membrane fluidity. Specifically, we address the role of the cargo lipid, which, by occupying the transporter, imposes changes in its dynamics and, consequently, predisposes the cargo to disembark in the correct target membrane.
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Affiliation(s)
- Alena Ballekova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czechia.
| | - Andrea Eisenreichova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Bartosz Różycki
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| | - Evzen Boura
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Jana Humpolickova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czechia.
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Liu D, Yuan H, Chen S, Ferro-Novick S, Novick P. Different ER-plasma membrane tethers play opposing roles in autophagy of the cortical ER. Proc Natl Acad Sci U S A 2024; 121:e2321991121. [PMID: 38838012 PMCID: PMC11181077 DOI: 10.1073/pnas.2321991121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 05/08/2024] [Indexed: 06/07/2024] Open
Abstract
The endoplasmic reticulum (ER) undergoes degradation by selective macroautophagy (ER-phagy) in response to starvation or the accumulation of misfolded proteins within its lumen. In yeast, actin assembly at sites of contact between the cortical ER (cER) and endocytic pits acts to displace elements of the ER from their association with the plasma membrane (PM) so they can interact with the autophagosome assembly machinery near the vacuole. A collection of proteins tether the cER to the PM. Of these, Scs2/22 and Ist2 are required for cER-phagy, most likely through their roles in lipid transport, while deletion of the tricalbins, TCB1/2/3, bypasses those requirements. An artificial ER-PM tether blocks cER-phagy in both the wild type (WT) and a strain lacking endogenous tethers, supporting the importance of cER displacement from the PM. Scs2 and Ist2 can be cross-linked to the selective cER-phagy receptor, Atg40. The COPII cargo adaptor subunit, Lst1, associates with Atg40 and is required for cER-phagy. This requirement is also bypassed by deletion of the ER-PM tethers, suggesting a role for Lst1 prior to the displacement of the cER from the PM during cER-phagy. Although pexophagy and mitophagy also require actin assembly, deletion of ER-PM tethers does not bypass those requirements. We propose that within the context of rapamycin-induced cER-phagy, Scs2/22, Ist2, and Lst1 promote the local displacement of an element of the cER from the cortex, while Tcb1/2/3 act in opposition, anchoring the cER to the plasma membrane.
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Affiliation(s)
- Dongmei Liu
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA92093-0668
| | - Hua Yuan
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA92093-0668
| | - Shuliang Chen
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA92093-0668
| | - Susan Ferro-Novick
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA92093-0668
| | - Peter Novick
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA92093-0668
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Nenadic A, Zaman MF, Johansen J, Volpiana MW, Beh CT. Increased Phospholipid Flux Bypasses Overlapping Essential Requirements for the Yeast Sac1p Phosphoinositide Phosphatase and ER-PM Membrane Contact Sites. J Biol Chem 2023; 299:105092. [PMID: 37507017 PMCID: PMC10470028 DOI: 10.1016/j.jbc.2023.105092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 07/13/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
In budding yeast cells, much of the inner surface of the plasma membrane (PM) is covered with the endoplasmic reticulum (ER). This association is mediated by seven ER membrane proteins that confer cortical ER-PM association at membrane contact sites (MCSs). Several of these membrane "tether" proteins are known to physically interact with the phosphoinositide phosphatase Sac1p. However, it is unclear how or if these interactions are necessary for their interdependent functions. We find that SAC1 inactivation in cells lacking the homologous synaptojanin-like genes INP52 and INP53 results in a significant increase in cortical ER-PM MCSs. We show in sac1Δ, sac1tsinp52Δ inp53Δ, or Δ-super-tether (Δ-s-tether) cells lacking all seven ER-PM tethering genes that phospholipid biosynthesis is disrupted and phosphoinositide distribution is altered. Furthermore, SAC1 deletion in Δ-s-tether cells results in lethality, indicating a functional overlap between SAC1 and ER-PM tethering genes. Transcriptomic profiling indicates that SAC1 inactivation in either Δ-s-tether or inp52Δ inp53Δ cells induces an ER membrane stress response and elicits phosphoinositide-dependent changes in expression of autophagy genes. In addition, by isolating high-copy suppressors that rescue sac1Δ Δ-s-tether lethality, we find that key phospholipid biosynthesis genes bypass the overlapping function of SAC1 and ER-PM tethers and that overexpression of the phosphatidylserine/phosphatidylinositol-4-phosphate transfer protein Osh6 also provides limited suppression. Combined with lipidomic analysis and determinations of intracellular phospholipid distributions, these results suggest that Sac1p and ER phospholipid flux controls lipid distribution to drive Osh6p-dependent phosphatidylserine/phosphatidylinositol-4-phosphate counter-exchange at ER-PM MCSs.
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Affiliation(s)
- Aleksa Nenadic
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Mohammad F Zaman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Jesper Johansen
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Matthew W Volpiana
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Christopher T Beh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada; Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada.
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Subra M, Antonny B, Mesmin B. New insights into the OSBP‒VAP cycle. Curr Opin Cell Biol 2023; 82:102172. [PMID: 37245352 DOI: 10.1016/j.ceb.2023.102172] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 04/16/2023] [Accepted: 04/24/2023] [Indexed: 05/30/2023]
Abstract
VAP-A is a major endoplasmic reticulum (ER) receptor that allows this organelle to engage numerous membrane contact sites with other organelles. One highly studied example is the formation of contact sites through VAP-A interaction with Oxysterol-binding protein (OSBP). This lipid transfer protein transports cholesterol from the ER to the trans-Golgi network owing to the counter-exchange of the phosphoinositide PI(4)P. In this review, we highlight recent studies that advance our understanding of the OSBP cycle and extend the model of lipid exchange to other cellular contexts and other physiological and pathological conditions.
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Affiliation(s)
- Mélody Subra
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 Route des Lucioles, 06560, Valbonne, France
| | - Bruno Antonny
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 Route des Lucioles, 06560, Valbonne, France.
| | - Bruno Mesmin
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 Route des Lucioles, 06560, Valbonne, France.
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Vormittag S, Ende RJ, Derré I, Hilbi H. Pathogen vacuole membrane contact sites - close encounters of the fifth kind. MICROLIFE 2023; 4:uqad018. [PMID: 37223745 PMCID: PMC10117887 DOI: 10.1093/femsml/uqad018] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/30/2023] [Accepted: 04/06/2023] [Indexed: 05/25/2023]
Abstract
Vesicular trafficking and membrane fusion are well-characterized, versatile, and sophisticated means of 'long range' intracellular protein and lipid delivery. Membrane contact sites (MCS) have been studied in far less detail, but are crucial for 'short range' (10-30 nm) communication between organelles, as well as between pathogen vacuoles and organelles. MCS are specialized in the non-vesicular trafficking of small molecules such as calcium and lipids. Pivotal MCS components important for lipid transfer are the VAP receptor/tether protein, oxysterol binding proteins (OSBPs), the ceramide transport protein CERT, the phosphoinositide phosphatase Sac1, and the lipid phosphatidylinositol 4-phosphate (PtdIns(4)P). In this review, we discuss how these MCS components are subverted by bacterial pathogens and their secreted effector proteins to promote intracellular survival and replication.
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Affiliation(s)
| | | | - Isabelle Derré
- Corresponding author. Department of Microbiology, Immunology and Cancer Biology, University of Virginia, 1340 Jefferson Park Ave, Charlottesville, VA 22908, United States. Tel: +1-434-924-2330; E-mail:
| | - Hubert Hilbi
- Corresponding author. Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006 Zürich, Switzerland. Tel: +41-44-634-2650; E-mail:
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8
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Subra M, Dezi M, Bigay J, Lacas-Gervais S, Di Cicco A, Araújo ARD, Abélanet S, Fleuriot L, Debayle D, Gautier R, Patel A, Roussi F, Antonny B, Lévy D, Mesmin B. VAP-A intrinsically disordered regions enable versatile tethering at membrane contact sites. Dev Cell 2023; 58:121-138.e9. [PMID: 36693319 DOI: 10.1016/j.devcel.2022.12.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 10/21/2022] [Accepted: 12/20/2022] [Indexed: 01/24/2023]
Abstract
Membrane contact sites (MCSs) are heterogeneous in shape, composition, and dynamics. Despite this diversity, VAP proteins act as receptors for multiple FFAT motif-containing proteins and drive the formation of most MCSs that involve the endoplasmic reticulum (ER). Although the VAP-FFAT interaction is well characterized, no model explains how VAP adapts to its partners in various MCSs. We report that VAP-A localization to different MCSs depends on its intrinsically disordered regions (IDRs) in human cells. VAP-A interaction with PTPIP51 and VPS13A at ER-mitochondria MCS conditions mitochondria fusion by promoting lipid transfer and cardiolipin buildup. VAP-A also enables lipid exchange at ER-Golgi MCS by interacting with oxysterol-binding protein (OSBP) and CERT. However, removing IDRs from VAP-A restricts its distribution and function to ER-mitochondria MCS. Our data suggest that IDRs do not modulate VAP-A preference toward specific partners but do adjust their geometry to MCS organization and lifetime constraints. Thus, IDR-mediated VAP-A conformational flexibility ensures membrane tethering plasticity and efficiency.
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Affiliation(s)
- Mélody Subra
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France
| | - Manuela Dezi
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Laboratoire Physico-Chimie Curie, 75005 Paris, France
| | - Joëlle Bigay
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France
| | - Sandra Lacas-Gervais
- Université Côte d'Azur, Centre Commun de Microscopie Appliquée, Parc Valrose, 06000 Nice, France
| | - Aurélie Di Cicco
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Laboratoire Physico-Chimie Curie, 75005 Paris, France
| | - Ana Rita Dias Araújo
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France
| | - Sophie Abélanet
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France
| | - Lucile Fleuriot
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France
| | - Delphine Debayle
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France
| | - Romain Gautier
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France
| | - Amanda Patel
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France
| | - Fanny Roussi
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Bruno Antonny
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France
| | - Daniel Lévy
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Laboratoire Physico-Chimie Curie, 75005 Paris, France
| | - Bruno Mesmin
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne, France.
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Thomas FB, Omnus DJ, Bader JM, Chung GH, Kono N, Stefan CJ. Tricalbin proteins regulate plasma membrane phospholipid homeostasis. Life Sci Alliance 2022; 5:5/8/e202201430. [PMID: 35440494 PMCID: PMC9018018 DOI: 10.26508/lsa.202201430] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/03/2022] [Accepted: 04/04/2022] [Indexed: 12/26/2022] Open
Abstract
The evolutionarily conserved extended synaptotagmin (E-Syt) proteins are calcium-activated lipid transfer proteins that function at contacts between the ER and plasma membrane (ER-PM contacts). However, roles of the E-Syt family members in PM lipid organisation remain incomplete. Among the E-Syt family, the yeast tricalbin (Tcb) proteins are essential for PM integrity upon heat stress, but it is not known how they contribute to PM maintenance. Using quantitative lipidomics and microscopy, we find that the Tcb proteins regulate phosphatidylserine homeostasis at the PM. Moreover, upon heat-induced membrane stress, Tcb3 co-localises with the PM protein Sfk1 that is implicated in PM phospholipid asymmetry and integrity. The Tcb proteins also control the PM targeting of the known phosphatidylserine effector Pkc1 upon heat-induced stress. Phosphatidylserine has evolutionarily conserved roles in PM organisation, integrity, and repair. We propose that phospholipid regulation is an ancient essential function of E-Syt family members required for PM integrity.
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Affiliation(s)
- Ffion B Thomas
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Deike J Omnus
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Jakob M Bader
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Gary Hc Chung
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Nozomu Kono
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Christopher J Stefan
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
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Quon E, Nenadic A, Zaman MF, Johansen J, Beh CT. ER-PM membrane contact site regulation by yeast ORPs and membrane stress pathways. PLoS Genet 2022; 18:e1010106. [PMID: 35239652 PMCID: PMC8923467 DOI: 10.1371/journal.pgen.1010106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/15/2022] [Accepted: 02/16/2022] [Indexed: 02/01/2023] Open
Abstract
In yeast, at least seven proteins (Ice2p, Ist2p, Scs2/22p, Tcb1-Tcb3p) affect cortical endoplasmic reticulum (ER) tethering and contact with the plasma membrane (PM). In Δ-super-tether (Δ-s-tether) cells that lack these tethers, cortical ER-PM association is all but gone. Yeast OSBP homologue (Osh) proteins are also implicated in membrane contact site (MCS) assembly, perhaps as subunits for multicomponent tethers, though their function at MCSs involves intermembrane lipid transfer. Paradoxically, when analyzed by fluorescence and electron microscopy, the elimination of the OSH gene family does not reduce cortical ER-PM association but dramatically increases it. In response to the inactivation of all Osh proteins, the yeast E-Syt (extended-synaptotagmin) homologue Tcb3p is post-transcriptionally upregulated thereby generating additional Tcb3p-dependent ER-PM MCSs for recruiting more cortical ER to the PM. Although the elimination of OSH genes and the deletion of ER-PM tether genes have divergent effects on cortical ER-PM association, both elicit the Environmental Stress Response (ESR). Through comparisons of transcriptomic profiles of cells lacking OSH genes or ER-PM tethers, changes in ESR expression are partially manifested through the induction of the HOG (high-osmolarity glycerol) PM stress pathway or the ER-specific UPR (unfolded protein response) pathway, respectively. Defects in either UPR or HOG pathways also increase ER-PM MCSs, and expression of extra “artificial ER-PM membrane staples” rescues growth of UPR mutants challenged with lethal ER stress. Transcriptome analysis of OSH and Δ-s-tether mutants also revealed dysregulation of inositol-dependent phospholipid gene expression, and the combined lethality of osh4Δ and Δ-s-tether mutations is suppressed by overexpression of the phosphatidic acid biosynthetic gene, DGK1. These findings establish that the Tcb3p tether is induced by ER and PM stresses and ER-PM MCSs augment responses to membrane stresses, which are integrated through the broader ESR pathway. Membrane contact sites (MCSs) between the two largest cellular membranes, the endoplasmic reticulum (ER) and the plasma membrane (PM), are regulatory interfaces for lipid synthesis and bidirectional transport. The yeast Osh protein family, which represents the seven yeast oxysterol-binding protein related proteins (ORPs), is implicated in MCS regulation and lipid transfer between membranes. Ironically, we find that when all Osh proteins eliminated, ER-PM association is not reduced but significantly increases. We hypothesized this increase is due to compensatory increases in levels of tether proteins that physically link the ER and PM. In fact, in response to inactivating Osh protein expression, amounts of the tether protein Tcb3 increase and more ER-PM MCSs are produced. By testing the genomic transcriptional responses to the elimination of OSH and ER-PM tether genes, we find these mutants disrupt phospholipid regulation and they elicit the Environmental Stress Response (ESR) pathway, which integrates many different responses needed for recovery after cellular stress. OSH and ER-PM tether genes affect specific stress response pathways that impact the PM and ER, respectively. Combining OSH and tether mutations results in cell lethality, but these cells survive by increased expression of a key phospholipid biosynthetic gene. Based on these results, we propose that OSH and ER-PM tether genes affect phospholipid regulation and protect the PM and ER through membrane stress responses integrated through the ESR pathway.
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Affiliation(s)
- Evan Quon
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Aleksa Nenadic
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Mohammad F. Zaman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Jesper Johansen
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Christopher T. Beh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, Canada
- * E-mail:
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11
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Arora A, Taskinen JH, Olkkonen VM. Coordination of inter-organelle communication and lipid fluxes by OSBP-related proteins. Prog Lipid Res 2022; 86:101146. [PMID: 34999137 DOI: 10.1016/j.plipres.2022.101146] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/10/2021] [Accepted: 01/03/2022] [Indexed: 12/31/2022]
Abstract
Oxysterol-binding protein (OSBP) and OSBP-related proteins (ORPs) constitute one of the largest families of lipid-binding/transfer proteins (LTPs) in eukaryotes. The current view is that many of them mediate inter-organelle lipid transfer over membrane contact sites (MCS). The transfer occurs in several cases in a 'counter-current' fashion: A lipid such as cholesterol or phosphatidylserine (PS) is transferred against its concentration gradient driven by transport of a phosphoinositide in the opposite direction. In this way ORPs are envisioned to maintain the distinct organelle lipid compositions, with impacts on multiple organelle functions. However, the functions of ORPs extend beyond lipid homeostasis to regulation of processes such as cell survival, proliferation and migration. Important expanding areas of mammalian ORP research include their roles in viral and bacterial infections, cancers, and neuronal function. The yeast OSBP homologue (Osh) proteins execute multifaceted functions in sterol and glycerophospholipid homeostasis, post-Golgi vesicle transport, phosphatidylinositol-4-phosphate, sphingolipid and target of rapamycin (TOR) signalling, and cell cycle control. These observations identify ORPs as lipid transporters and coordinators of signals with an unforeseen variety of cellular processes. Understanding their activities not only enlightens the biology of the living cell but also allows their employment as targets of new therapeutic approaches for disease.
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Affiliation(s)
- Amita Arora
- Minerva Foundation Institute for Medical Research, and Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland
| | - Juuso H Taskinen
- Minerva Foundation Institute for Medical Research, and Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, and Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland.
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12
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Egea PF. Mechanisms of Non-Vesicular Exchange of Lipids at Membrane Contact Sites: Of Shuttles, Tunnels and, Funnels. Front Cell Dev Biol 2021; 9:784367. [PMID: 34912813 PMCID: PMC8667587 DOI: 10.3389/fcell.2021.784367] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Eukaryotic cells are characterized by their exquisite compartmentalization resulting from a cornucopia of membrane-bound organelles. Each of these compartments hosts a flurry of biochemical reactions and supports biological functions such as genome storage, membrane protein and lipid biosynthesis/degradation and ATP synthesis, all essential to cellular life. Acting as hubs for the transfer of matter and signals between organelles and throughout the cell, membrane contacts sites (MCSs), sites of close apposition between membranes from different organelles, are essential to cellular homeostasis. One of the now well-acknowledged function of MCSs involves the non-vesicular trafficking of lipids; its characterization answered one long-standing question of eukaryotic cell biology revealing how some organelles receive and distribute their membrane lipids in absence of vesicular trafficking. The endoplasmic reticulum (ER) in synergy with the mitochondria, stands as the nexus for the biosynthesis and distribution of phospholipids (PLs) throughout the cell by contacting nearly all other organelle types. MCSs create and maintain lipid fluxes and gradients essential to the functional asymmetry and polarity of biological membranes throughout the cell. Membrane apposition is mediated by proteinaceous tethers some of which function as lipid transfer proteins (LTPs). We summarize here the current state of mechanistic knowledge of some of the major classes of LTPs and tethers based on the available atomic to near-atomic resolution structures of several "model" MCSs from yeast but also in Metazoans; we describe different models of lipid transfer at MCSs and analyze the determinants of their specificity and directionality. Each of these systems illustrate fundamental principles and mechanisms for the non-vesicular exchange of lipids between eukaryotic membrane-bound organelles essential to a wide range of cellular processes such as at PL biosynthesis and distribution, lipid storage, autophagy and organelle biogenesis.
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Affiliation(s)
- Pascal F. Egea
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
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13
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Ikhlef S, Lipp NF, Delfosse V, Fuggetta N, Bourguet W, Magdeleine M, Drin G. Functional analyses of phosphatidylserine/PI(4)P exchangers with diverse lipid species and membrane contexts reveal unanticipated rules on lipid transfer. BMC Biol 2021; 19:248. [PMID: 34801011 PMCID: PMC8606082 DOI: 10.1186/s12915-021-01183-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 11/04/2021] [Indexed: 11/14/2022] Open
Abstract
Background Lipid species are accurately distributed in the eukaryotic cell so that organelle and plasma membranes have an adequate lipid composition to support numerous cellular functions. In the plasma membrane, a precise regulation of the level of lipids such as phosphatidylserine, PI(4)P, and PI(4,5)P2, is critical for maintaining the signaling competence of the cell. Several lipid transfer proteins of the ORP/Osh family contribute to this fine-tuning by delivering PS, synthesized in the endoplasmic reticulum, to the plasma membrane in exchange for PI(4)P. To get insights into the role of these PS/PI(4)P exchangers in regulating plasma membrane features, we question how they selectively recognize and transfer lipid ligands with different acyl chains, whether these proteins exchange PS exclusively for PI(4)P or additionally for PI(4,5)P2, and how sterol abundance in the plasma membrane impacts their activity. Results We measured in vitro how the yeast Osh6p and human ORP8 transported PS and PI(4)P subspecies of diverse length and unsaturation degree between membranes by fluorescence-based assays. We established that the exchange activity of Osh6p and ORP8 strongly depends on whether these ligands are saturated or not, and is high with representative cellular PS and PI(4)P subspecies. Unexpectedly, we found that the speed at which these proteins individually transfer lipid ligands between membranes is inversely related to their affinity for them and that high-affinity ligands must be exchanged to be transferred more rapidly. Next we determined that Osh6p and ORP8 cannot use PI(4,5)P2 for exchange processes, because it is a low-affinity ligand, and do not transfer more PS into sterol-rich membranes. Conclusions Our study provides new insights into PS/PI(4)P exchangers by indicating the degree to which they can regulate the acyl chain composition of the PM, and how they control PM phosphoinositide levels. Moreover, we establish general rules on how the activity of lipid transfer proteins relates to their affinity for ligands. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01183-1.
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Affiliation(s)
- Souade Ikhlef
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France
| | - Nicolas-Frédéric Lipp
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France.,Current position: Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Vanessa Delfosse
- Centre de Biologie Structurale, INSERM, CNRS, Université de Montpellier, Montpellier, France
| | - Nicolas Fuggetta
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France
| | - William Bourguet
- Centre de Biologie Structurale, INSERM, CNRS, Université de Montpellier, Montpellier, France
| | - Maud Magdeleine
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France
| | - Guillaume Drin
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, 660 route des lucioles, 06560, Valbonne, France.
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14
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Eisenreichova A, Różycki B, Boura E, Humpolickova J. Osh6 Revisited: Control of PS Transport by the Concerted Actions of PI4P and Sac1 Phosphatase. Front Mol Biosci 2021; 8:747601. [PMID: 34712698 PMCID: PMC8546167 DOI: 10.3389/fmolb.2021.747601] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/08/2021] [Indexed: 12/03/2022] Open
Abstract
Osh6, a member of the oxysterol-binding protein-related protein (ORP) family, is a lipid transport protein that is involved in the transport of phosphatidylserine (PS) between the endoplasmic reticulum (ER) and the plasma membrane (PM). We used a biophysical approach to characterize its transport mechanism in detail. We examined the transport of all potential ligands of Osh6. PI4P and PS are the best described lipid cargo molecules; in addition, we showed that PIP2 can be transported by Osh6 as well. So far, it was the exchange between the two cargo molecules, PS and PI4P, in the lipid-binding pocket of Osh6 that was considered an essential driving force for the PS transport. However, we showed that Osh6 can efficiently transport PS along the gradient without the help of PI4P and that PI4P inhibits the PS transport along its gradient. This observation highlights that the exchange between PS and PI4P is indeed crucial, but PI4P bound to the protein rather than intensifying the PS transport suppresses it. We considered this to be important for the transport directionality as it prevents PS from returning back from the PM where its concentration is high to the ER where it is synthesized. Our results also highlighted the importance of the ER resident Sac1 phosphatase that enables the PS transport and ensures its directionality by PI4P consumption. Furthermore, we showed that the Sac1 activity is regulated by the negative charge of the membrane that can be provided by PS or PI anions in the case of the ER membrane.
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Affiliation(s)
- Andrea Eisenreichova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Bartosz Różycki
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| | - Evzen Boura
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Jana Humpolickova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czechia
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15
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Lenoir G, D'Ambrosio JM, Dieudonné T, Čopič A. Transport Pathways That Contribute to the Cellular Distribution of Phosphatidylserine. Front Cell Dev Biol 2021; 9:737907. [PMID: 34540851 PMCID: PMC8440936 DOI: 10.3389/fcell.2021.737907] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/10/2021] [Indexed: 12/05/2022] Open
Abstract
Phosphatidylserine (PS) is a negatively charged phospholipid that displays a highly uneven distribution within cellular membranes, essential for establishment of cell polarity and other processes. In this review, we discuss how combined action of PS biosynthesis enzymes in the endoplasmic reticulum (ER), lipid transfer proteins (LTPs) acting within membrane contact sites (MCS) between the ER and other compartments, and lipid flippases and scramblases that mediate PS flip-flop between membrane leaflets controls the cellular distribution of PS. Enrichment of PS in specific compartments, in particular in the cytosolic leaflet of the plasma membrane (PM), requires input of energy, which can be supplied in the form of ATP or by phosphoinositides. Conversely, coupling between PS synthesis or degradation, PS flip-flop and PS transfer may enable PS transfer by passive flow. Such scenario is best documented by recent work on the formation of autophagosomes. The existence of lateral PS nanodomains, which is well-documented in the case of the PM and postulated for other compartments, can change the steepness or direction of PS gradients between compartments. Improvements in cellular imaging of lipids and membranes, lipidomic analysis of complex cellular samples, reconstitution of cellular lipid transport reactions and high-resolution structural data have greatly increased our understanding of cellular PS homeostasis. Our review also highlights how budding yeast has been instrumental for our understanding of the organization and transport of PS in cells.
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Affiliation(s)
- Guillaume Lenoir
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell, Gif-sur-Yvette, France
| | - Juan Martín D'Ambrosio
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, Montpellier, France
| | - Thibaud Dieudonné
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Alenka Čopič
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, Montpellier, France
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16
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Reinisch KM, Prinz WA. Mechanisms of nonvesicular lipid transport. J Cell Biol 2021; 220:211813. [PMID: 33605998 PMCID: PMC7901144 DOI: 10.1083/jcb.202012058] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 02/02/2021] [Accepted: 02/02/2021] [Indexed: 12/18/2022] Open
Abstract
We have long known that lipids traffic between cellular membranes via vesicles but have only recently appreciated the role of nonvesicular lipid transport. Nonvesicular transport can be high volume, supporting biogenesis of rapidly expanding membranes, or more targeted and precise, allowing cells to rapidly alter levels of specific lipids in membranes. Most such transport probably occurs at membrane contact sites, where organelles are closely apposed, and requires lipid transport proteins (LTPs), which solubilize lipids to shield them from the aqueous phase during their transport between membranes. Some LTPs are cup like and shuttle lipid monomers between membranes. Others form conduits allowing lipid flow between membranes. This review describes what we know about nonvesicular lipid transfer mechanisms while also identifying many remaining unknowns: How do LTPs facilitate lipid movement from and into membranes, do LTPs require accessory proteins for efficient transfer in vivo, and how is directionality of transport determined?
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Affiliation(s)
- Karin M Reinisch
- Department of Cell Biology, Yale School of Medicine, New Haven, CT
| | - William A Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
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17
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Wong AKO, Young BP, Loewen CJ. Ist2 recruits the lipid transporters Osh6/7 to ER-PM contacts to maintain phospholipid metabolism. J Cell Biol 2021; 220:e201910161. [PMID: 34259806 PMCID: PMC8282664 DOI: 10.1083/jcb.201910161] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 04/13/2021] [Accepted: 06/15/2021] [Indexed: 12/26/2022] Open
Abstract
ER-plasma membrane (PM) contacts are proposed to be held together by distinct families of tethering proteins, which in yeast include the VAP homologues Scs2/22, the extended-synaptotagmin homologues Tcb1/2/3, and the TMEM16 homologue Ist2. It is unclear whether these tethers act redundantly or whether individual tethers have specific functions at contacts. Here, we show that Ist2 directly recruits the phosphatidylserine (PS) transport proteins and ORP family members Osh6 and Osh7 to ER-PM contacts through a binding site located in Ist2's disordered C-terminal tethering region. This interaction is required for phosphatidylethanolamine (PE) production by the PS decarboxylase Psd2, whereby PS transported from the ER to the PM by Osh6/7 is endocytosed to the site of Psd2 in endosomes/Golgi/vacuoles. This role for Ist2 and Osh6/7 in nonvesicular PS transport is specific, as other tethers/transport proteins do not compensate. Thus, we identify a molecular link between the ORP and TMEM16 families and a role for endocytosis of PS in PE synthesis.
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Affiliation(s)
| | | | - Christopher J.R. Loewen
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
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18
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de la Mora E, Dezi M, Di Cicco A, Bigay J, Gautier R, Manzi J, Polidori J, Castaño-Díez D, Mesmin B, Antonny B, Lévy D. Nanoscale architecture of a VAP-A-OSBP tethering complex at membrane contact sites. Nat Commun 2021; 12:3459. [PMID: 34103503 PMCID: PMC8187361 DOI: 10.1038/s41467-021-23799-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 05/12/2021] [Indexed: 02/05/2023] Open
Abstract
Membrane contact sites (MCS) are subcellular regions where two organelles appose their membranes to exchange small molecules, including lipids. Structural information on how proteins form MCS is scarce. We designed an in vitro MCS with two membranes and a pair of tethering proteins suitable for cryo-tomography analysis. It includes VAP-A, an ER transmembrane protein interacting with a myriad of cytosolic proteins, and oxysterol-binding protein (OSBP), a lipid transfer protein that transports cholesterol from the ER to the trans Golgi network. We show that VAP-A is a highly flexible protein, allowing formation of MCS of variable intermembrane distance. The tethering part of OSBP contains a central, dimeric, and helical T-shape region. We propose that the molecular flexibility of VAP-A enables the recruitment of partners of different sizes within MCS of adjustable thickness, whereas the T geometry of the OSBP dimer facilitates the movement of the two lipid-transfer domains between membranes.
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Affiliation(s)
- Eugenio de la Mora
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France
- Sorbonne Université, Paris, France
| | - Manuela Dezi
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.
- Sorbonne Université, Paris, France.
| | - Aurélie Di Cicco
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France
- Sorbonne Université, Paris, France
| | - Joëlle Bigay
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | - Romain Gautier
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | - John Manzi
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France
- Sorbonne Université, Paris, France
| | - Joël Polidori
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | | | - Bruno Mesmin
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
| | - Bruno Antonny
- CNRS UMR 7275, Université Côte d'Azur, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France.
| | - Daniel Lévy
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.
- Sorbonne Université, Paris, France.
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19
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Abstract
Our cells are comprised of billions of proteins, lipids, and other small molecules packed into their respective subcellular organelles, with the daunting task of maintaining cellular homeostasis over a lifetime. However, it is becoming increasingly evident that organelles do not act as autonomous discrete units but rather as interconnected hubs that engage in extensive communication through membrane contacts. In the last few years, our understanding of how these contacts coordinate organelle function has redefined our view of the cell. This review aims to present novel findings on the cellular interorganelle communication network and how its dysfunction may contribute to aging and neurodegeneration. The consequences of disturbed interorganellar communication are intimately linked with age-related pathologies. Given that both aging and neurodegenerative diseases are characterized by the concomitant failure of multiple cellular pathways, coordination of organelle communication and function could represent an emerging regulatory mechanism critical for long-term cellular homeostasis. We anticipate that defining the relationships between interorganelle communication, aging, and neurodegeneration will open new avenues for therapeutics.
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Affiliation(s)
- Maja Petkovic
- Department of Physiology, University of California at San Francisco, San Francisco, California 94158, USA
| | - Caitlin E O'Brien
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA
| | - Yuh Nung Jan
- Department of Physiology, University of California at San Francisco, San Francisco, California 94158, USA
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158, USA
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
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20
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Hewlett B, Singh NP, Vannier C, Galli T. ER-PM Contact Sites - SNARING Actors in Emerging Functions. Front Cell Dev Biol 2021; 9:635518. [PMID: 33681218 PMCID: PMC7928305 DOI: 10.3389/fcell.2021.635518] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/21/2021] [Indexed: 11/13/2022] Open
Abstract
The compartmentalisation achieved by confining cytoplasm into membrane-enclosed organelles in eukaryotic cells is essential for maintaining vital functions including ATP production, synthetic and degradative pathways. While intracellular organelles are highly specialised in these functions, the restricting membranes also impede exchange of molecules responsible for the synchronised and responsive cellular activities. The initial identification of contact sites between the ER and plasma membrane (PM) provided a potential candidate structure for communication between organelles without mixing by fusion. Over the past decades, research has revealed a far broader picture of the events. Membrane contact sites (MCSs) have been recognized as increasingly important actors in cell differentiation, plasticity and maintenance, and, upon dysfunction, responsible for pathological conditions such as cancer and neurodegenerative diseases. Present in multiple organelles and cell types, MCSs promote transport of lipids and Ca2+ homoeostasis, with a range of associated protein families. Interestingly, each MCS displays a unique molecular signature, adapted to organelle functions. This review will explore the literature describing the molecular components and interactions taking place at ER-PM contact sites, their functions, and implications in eukaryotic cells, particularly neurons, with emphasis on lipid transfer proteins and emerging function of SNAREs.
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Affiliation(s)
- Bailey Hewlett
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Neha Pratap Singh
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Christian Vannier
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Thierry Galli
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France.,GHU PARIS Psychiatrie and Neurosciences, Paris, France
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21
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Li C, Qian T, He R, Wan C, Liu Y, Yu H. Endoplasmic Reticulum-Plasma Membrane Contact Sites: Regulators, Mechanisms, and Physiological Functions. Front Cell Dev Biol 2021; 9:627700. [PMID: 33614657 PMCID: PMC7889955 DOI: 10.3389/fcell.2021.627700] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/13/2021] [Indexed: 12/13/2022] Open
Abstract
The endoplasmic reticulum (ER) forms direct membrane contact sites with the plasma membrane (PM) in eukaryotic cells. These ER-PM contact sites play essential roles in lipid homeostasis, ion dynamics, and cell signaling, which are carried out by protein-protein or protein-lipid interactions. Distinct tethering factors dynamically control the architecture of ER-PM junctions in response to intracellular signals or external stimuli. The physiological roles of ER-PM contact sites are dependent on a variety of regulators that individually or cooperatively perform functions in diverse cellular processes. This review focuses on proteins functioning at ER-PM contact sites and highlights the recent progress in their mechanisms and physiological roles.
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Affiliation(s)
- Chenlu Li
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Tiantian Qian
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ruyue He
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, United States
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
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22
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Delfosse V, Bourguet W, Drin G. Structural and Functional Specialization of OSBP-Related Proteins. ACTA ACUST UNITED AC 2020. [DOI: 10.1177/2515256420946627] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Lipids are precisely distributed in the eukaryotic cell where they help to define organelle identity and function, in addition to their structural role. Once synthesized, many lipids must be delivered to other compartments by non-vesicular routes, a process that is undertaken by proteins called Lipid Transfer Proteins (LTPs). OSBP and the closely-related ORP and Osh proteins constitute a major, evolutionarily conserved family of LTPs in eukaryotes. Most of these target one or more subcellular regions, and membrane contact sites in particular, where two organelle membranes are in close proximity. It was initially thought that such proteins were strictly dedicated to sterol sensing or transport. However, over the last decade, numerous studies have revealed that these proteins have many more functions, and we have expanded our understanding of their mechanisms. In particular, many of them are lipid exchangers that exploit PI(4)P or possibly other phosphoinositide gradients to directionally transfer sterol or PS between two compartments. Importantly, these transfer activities are tightly coupled to processes such as lipid metabolism, cellular signalling and vesicular trafficking. This review describes the molecular architecture of OSBP/ORP/Osh proteins, showing how their specific structural features and internal configurations impart unique cellular functions.
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Affiliation(s)
- Vanessa Delfosse
- Centre de Biochimie Structurale, Inserm, CNRS, Univ Montpellier, Montpellier, France
| | - William Bourguet
- Centre de Biochimie Structurale, Inserm, CNRS, Univ Montpellier, Montpellier, France
| | - Guillaume Drin
- CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Université Côte d’Azur, Valbonne, France
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23
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Zaman MF, Nenadic A, Radojičić A, Rosado A, Beh CT. Sticking With It: ER-PM Membrane Contact Sites as a Coordinating Nexus for Regulating Lipids and Proteins at the Cell Cortex. Front Cell Dev Biol 2020; 8:675. [PMID: 32793605 PMCID: PMC7387695 DOI: 10.3389/fcell.2020.00675] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/03/2020] [Indexed: 12/31/2022] Open
Abstract
Membrane contact sites between the cortical endoplasmic reticulum (ER) and the plasma membrane (PM) provide a direct conduit for small molecule transfer and signaling between the two largest membranes of the cell. Contact is established through ER integral membrane proteins that physically tether the two membranes together, though the general mechanism is remarkably non-specific given the diversity of different tethering proteins. Primary tethers including VAMP-associated proteins (VAPs), Anoctamin/TMEM16/Ist2p homologs, and extended synaptotagmins (E-Syts), are largely conserved in most eukaryotes and are both necessary and sufficient for establishing ER-PM association. In addition, other species-specific ER-PM tether proteins impart unique functional attributes to both membranes at the cell cortex. This review distils recent functional and structural findings about conserved and species-specific tethers that form ER-PM contact sites, with an emphasis on their roles in the coordinate regulation of lipid metabolism, cellular structure, and responses to membrane stress.
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Affiliation(s)
- Mohammad F Zaman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Aleksa Nenadic
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Ana Radojičić
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.,Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Abel Rosado
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Christopher T Beh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.,The Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC, Canada
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Lipp NF, Ikhlef S, Milanini J, Drin G. Lipid Exchangers: Cellular Functions and Mechanistic Links With Phosphoinositide Metabolism. Front Cell Dev Biol 2020; 8:663. [PMID: 32793602 PMCID: PMC7385082 DOI: 10.3389/fcell.2020.00663] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 07/01/2020] [Indexed: 12/28/2022] Open
Abstract
Lipids are amphiphilic molecules that self-assemble to form biological membranes. Thousands of lipid species coexist in the cell and, once combined, define organelle identity. Due to recent progress in lipidomic analysis, we now know how lipid composition is finely tuned in different subcellular regions. Along with lipid synthesis, remodeling and flip-flop, lipid transfer is one of the active processes that regulates this intracellular lipid distribution. It is mediated by Lipid Transfer Proteins (LTPs) that precisely move certain lipid species across the cytosol and between the organelles. A particular subset of LTPs from three families (Sec14, PITP, OSBP/ORP/Osh) act as lipid exchangers. A striking feature of these exchangers is that they use phosphatidylinositol or phosphoinositides (PIPs) as a lipid ligand and thereby have specific links with PIP metabolism and are thus able to both control the lipid composition of cellular membranes and their signaling capacity. As a result, they play pivotal roles in cellular processes such as vesicular trafficking and signal transduction at the plasma membrane. Recent data have shown that some PIPs are used as energy by lipid exchangers to generate lipid gradients between organelles. Here we describe the importance of lipid counter-exchange in the cell, its structural basis, and presumed links with pathologies.
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Affiliation(s)
- Nicolas-Frédéric Lipp
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS, Université Côte d'Azur, Valbonne, France
| | - Souade Ikhlef
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS, Université Côte d'Azur, Valbonne, France
| | - Julie Milanini
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS, Université Côte d'Azur, Valbonne, France
| | - Guillaume Drin
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS, Université Côte d'Azur, Valbonne, France
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25
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Petkovic M, Oses-Prieto J, Burlingame A, Jan LY, Jan YN. TMEM16K is an interorganelle regulator of endosomal sorting. Nat Commun 2020; 11:3298. [PMID: 32620747 PMCID: PMC7335067 DOI: 10.1038/s41467-020-17016-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 06/05/2020] [Indexed: 12/17/2022] Open
Abstract
Communication between organelles is essential for their cellular homeostasis. Neurodegeneration reflects the declining ability of neurons to maintain cellular homeostasis over a lifetime, where the endolysosomal pathway plays a prominent role by regulating protein and lipid sorting and degradation. Here we report that TMEM16K, an endoplasmic reticulum lipid scramblase causative for spinocerebellar ataxia (SCAR10), is an interorganelle regulator of the endolysosomal pathway. We identify endosomal transport as a major functional cluster of TMEM16K in proximity biotinylation proteomics analyses. TMEM16K forms contact sites with endosomes, reconstituting split-GFP with the small GTPase RAB7. Our study further implicates TMEM16K lipid scrambling activity in endosomal sorting at these sites. Loss of TMEM16K function led to impaired endosomal retrograde transport and neuromuscular function, one of the symptoms of SCAR10. Thus, TMEM16K-containing ER-endosome contact sites represent clinically relevant platforms for regulating endosomal sorting.
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Affiliation(s)
- Maja Petkovic
- Departments of Physiology, Biochemistry and Biophysics, University of California at San Francisco, San Francisco, CA, 94158, USA.
| | - Juan Oses-Prieto
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Alma Burlingame
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Lily Yeh Jan
- Departments of Physiology, Biochemistry and Biophysics, University of California at San Francisco, San Francisco, CA, 94158, USA
- Howard Hughes Medical Institute, University of California, San Francisco, CA, USA
| | - Yuh Nung Jan
- Departments of Physiology, Biochemistry and Biophysics, University of California at San Francisco, San Francisco, CA, 94158, USA.
- Howard Hughes Medical Institute, University of California, San Francisco, CA, USA.
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26
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First person – Juan Martín D'Ambrosio. J Cell Sci 2020. [DOI: 10.1242/jcs.248096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Juan Martín D'Ambrosio is first author on ‘ Osh6 requires Ist2 for localization to the ER–PM contacts and efficient phosphatidylserine transport in budding yeast’, published in JCS. Juan Martín conducted the research described in this article while a postdoc in the lab of Alenka Copic at Institut Jacques Monod, Paris, France, investigating yeast and plant biology, with an interest in membrane contact sites, signal transduction, lipid transport proteins and phospholipase C.
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