1
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Hamaï A, Drin G. Specificity of lipid transfer proteins: An in vitro story. Biochimie 2024; 227:85-110. [PMID: 39304019 DOI: 10.1016/j.biochi.2024.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 09/06/2024] [Accepted: 09/17/2024] [Indexed: 09/22/2024]
Abstract
Lipids, which are highly diverse, are finely distributed between organelle membranes and the plasma membrane (PM) of eukaryotic cells. As a result, each compartment has its own lipid composition and molecular identity, which is essential for the functional fate of many proteins. This distribution of lipids depends on two main processes: lipid synthesis, which takes place in different subcellular regions, and the transfer of these lipids between and across membranes. This review will discuss the proteins that carry lipids throughout the cytosol, called LTPs (Lipid Transfer Proteins). More than the modes of action or biological roles of these proteins, we will focus on the in vitro strategies employed during the last 60 years to address a critical question: What are the lipid ligands of these LTPs? We will describe the extent to which these strategies, combined with structural data and investigations in cells, have made it possible to discover proteins, namely ORPs, Sec14, PITPs, STARDs, Ups/PRELIs, START-like, SMP-domain containing proteins, and bridge-like LTPs, which compose some of the main eukaryotic LTP families, and their lipid ligands. We will see how these approaches have played a central role in cell biology, showing that LTPs can connect distant metabolic branches, modulate the composition of cell membranes, and even create new subcellular compartments.
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Affiliation(s)
- Amazigh Hamaï
- Université Côte d'Azur, CNRS and Inserm, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 660 route des lucioles, 06560, Valbonne Sophia Antipolis, France
| | - Guillaume Drin
- Université Côte d'Azur, CNRS and Inserm, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, 660 route des lucioles, 06560, Valbonne Sophia Antipolis, France.
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2
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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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Miyata Y, Takahashi K, Lee Y, Sultan CS, Kuribayashi R, Takahashi M, Hata K, Bamba T, Izumi Y, Liu K, Uemura T, Nomura N, Iwata S, Nagata S, Nishizawa T, Segawa K. Membrane structure-responsive lipid scrambling by TMEM63B to control plasma membrane lipid distribution. Nat Struct Mol Biol 2024:10.1038/s41594-024-01411-6. [PMID: 39424995 DOI: 10.1038/s41594-024-01411-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Accepted: 09/27/2024] [Indexed: 10/21/2024]
Abstract
Phospholipids are asymmetrically distributed in the plasma membrane (PM), with phosphatidylcholine and sphingomyelin abundant in the outer leaflet. However, the mechanisms by which their distribution is regulated remain unclear. Here, we show that transmembrane protein 63B (TMEM63B) functions as a membrane structure-responsive lipid scramblase localized at the PM and lysosomes, activating bidirectional lipid translocation upon changes in membrane curvature and thickness. TMEM63B contains two intracellular loops with palmitoylated cysteine residue clusters essential for its scrambling function. TMEM63B deficiency alters phosphatidylcholine and sphingomyelin distributions in the PM. Persons with heterozygous mutations in TMEM63B are known to develop neurodevelopmental disorders. We show that V44M, the most frequent substitution, confers constitutive scramblase activity on TMEM63B, disrupting PM phospholipid asymmetry. We determined the cryo-electron microscopy structures of TMEM63B in its open and closed conformations, uncovering a lipid translocation pathway formed in response to changes in the membrane environment. Together, our results identify TMEM63B as a membrane structure-responsive scramblase that controls PM lipid distribution and we reveal the molecular basis for lipid scrambling and its biological importance.
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Affiliation(s)
- Yugo Miyata
- Department of Medical Chemistry, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
- Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Katsuya Takahashi
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Yongchan Lee
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Cheryl S Sultan
- Department of Medical Chemistry, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
- Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Risa Kuribayashi
- Department of Medical Chemistry, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
- Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Masatomo Takahashi
- Division of Metabolomics, Medical Research Center for High Depth Omics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Kosuke Hata
- Division of Metabolomics, Medical Research Center for High Depth Omics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Takeshi Bamba
- Division of Metabolomics, Medical Research Center for High Depth Omics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Yoshihiro Izumi
- Division of Metabolomics, Medical Research Center for High Depth Omics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Kehong Liu
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tomoko Uemura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Norimichi Nomura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - So Iwata
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Shigekazu Nagata
- Biochemistry and Immunology, World Premier International Research Center, Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Tomohiro Nishizawa
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan.
| | - Katsumori Segawa
- Department of Medical Chemistry, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan.
- Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
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4
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Li Z, Zhang L, Wang Z, Kang X, Jin H, Zhao W, Zhang J, Su H. Quantification of Phosphatidylserine Molecules on the Surface of Individual Cells Using Single-Molecule Force Spectroscopy. Anal Chem 2024; 96:676-684. [PMID: 38173079 DOI: 10.1021/acs.analchem.3c03517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Identification of the phosphatidylserine (PS) discrepancies occurring on the cellular membrane during apoptotic processes is of the utmost importance. However, monitoring the quantity of PS molecules in real-time at a single-cell level currently remains a challenging task. Here, we demonstrate this objective by leveraging the specific binding and reversible interaction exhibited by the zinc(II) dipyridinamine complex (ZnDPA) with PS. Lipoic acid-functionalized ZnDPA (LP-ZnDPA) was subsequently immobilized onto the surface of an atomic force microscopy cantilever to form a force probe, ALP-ZnDPA, enabling a PS-specific dynamic imaging and detection mode. By utilizing this technique, we can not only create a heat map of the expression level of PS with submicron resolution but also quantify the number of molecules present on a single cell's surface with a detection limit of 1.86 × 104 molecules. The feasibility of the proposed method is demonstrated through the analysis of PS expression levels in different cancer cell lines and at various stages of paclitaxel-induced apoptosis. This study represents the first application of a force probe to quantify PS molecules on the surface of individual cells, providing insight into dynamic changes in PS content during apoptosis at the molecular level and introducing a novel dimension to current detection methodologies.
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Affiliation(s)
- Zhirong Li
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010020, China
| | - Lulu Zhang
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010020, China
| | - Zhanzhong Wang
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010020, China
| | - Xiongli Kang
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010020, China
| | - Huiying Jin
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010020, China
| | - Wenjie Zhao
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010020, China
| | - Jun Zhang
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010020, China
| | - Haiquan Su
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010020, China
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5
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Avdonin PP, Blinova MS, Generalova GA, Emirova KM, Avdonin PV. The Role of the Complement System in the Pathogenesis of Infectious Forms of Hemolytic Uremic Syndrome. Biomolecules 2023; 14:39. [PMID: 38254639 PMCID: PMC10813406 DOI: 10.3390/biom14010039] [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: 09/30/2023] [Revised: 11/24/2023] [Accepted: 12/18/2023] [Indexed: 01/24/2024] Open
Abstract
Hemolytic uremic syndrome (HUS) is an acute disease and the most common cause of childhood acute renal failure. HUS is characterized by a triad of symptoms: microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. In most of the cases, HUS occurs as a result of infection caused by Shiga toxin-producing microbes: hemorrhagic Escherichia coli and Shigella dysenteriae type 1. They account for up to 90% of all cases of HUS. The remaining 10% of cases grouped under the general term atypical HUS represent a heterogeneous group of diseases with similar clinical signs. Emerging evidence suggests that in addition to E. coli and S. dysenteriae type 1, a variety of bacterial and viral infections can cause the development of HUS. In particular, infectious diseases act as the main cause of aHUS recurrence. The pathogenesis of most cases of atypical HUS is based on congenital or acquired defects of complement system. This review presents summarized data from recent studies, suggesting that complement dysregulation is a key pathogenetic factor in various types of infection-induced HUS. Separate links in the complement system are considered, the damage of which during bacterial and viral infections can lead to complement hyperactivation following by microvascular endothelial injury and development of acute renal failure.
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Affiliation(s)
- Piotr P. Avdonin
- Koltzov Institute of Developmental Biology RAS, ul. Vavilova, 26, 119334 Moscow, Russia; (M.S.B.); (P.V.A.)
| | - Maria S. Blinova
- Koltzov Institute of Developmental Biology RAS, ul. Vavilova, 26, 119334 Moscow, Russia; (M.S.B.); (P.V.A.)
| | - Galina A. Generalova
- Saint Vladimir Moscow City Children’s Clinical Hospital, 107014 Moscow, Russia; (G.A.G.); (K.M.E.)
- Department of Pediatrics, A.I. Evdokimov Moscow State University of Medicine and Dentistry, 127473 Moscow, Russia
| | - Khadizha M. Emirova
- Saint Vladimir Moscow City Children’s Clinical Hospital, 107014 Moscow, Russia; (G.A.G.); (K.M.E.)
- Department of Pediatrics, A.I. Evdokimov Moscow State University of Medicine and Dentistry, 127473 Moscow, Russia
| | - Pavel V. Avdonin
- Koltzov Institute of Developmental Biology RAS, ul. Vavilova, 26, 119334 Moscow, Russia; (M.S.B.); (P.V.A.)
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Chung WY, Ahuja M, McNally BA, Leibow SR, Ohman HKE, Movahed Abtahi A, Muallem S. PtdSer as a signaling lipid determined by privileged localization of ORP5 and ORP8 at ER/PM junctional foci to determine PM and ER PtdSer/PI(4)P ratio and cell function. Proc Natl Acad Sci U S A 2023; 120:e2301410120. [PMID: 37607230 PMCID: PMC10469337 DOI: 10.1073/pnas.2301410120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 07/11/2023] [Indexed: 08/24/2023] Open
Abstract
The membrane contact site ER/PM junctions are hubs for signaling pathways, including Ca2+ signaling. Phosphatidylserine (PtdSer) mediates various physiological functions; however, junctional PtdSer composition and the role of PtdSer in Ca2+ signaling and Ca2+-dependent gene regulation are not understood. Here, we show that STIM1-formed junctions are required for PI(4)P/PtdSer exchange by ORP5 and ORP8, which have reciprocal lipid exchange modes and function as a rheostat that sets the junctional PtdSer/PI(4)P ratio. Targeting the ORP5 and ORP8 and their lipid transfer ORD domains to PM subdomains revealed that ORP5 sets low and ORP8 high junctional PI(4)P/PtdSer ratio that controls STIM1-STIM1 and STIM1-Orai1 interaction and the activity of the SERCA pump to determine the pattern of receptor-evoked Ca2+ oscillations, and consequently translocation of NFAT to the nucleus. Significantly, targeting the ORP5 and ORP8 ORDs to the STIM1 ER subdomain reversed their function. Notably, changing PI(4)P/PtdSer ratio by hydrolysis of PM or ER PtdSer with targeted PtdSer-specific PLA1a1 reproduced the ORPs function. The function of the ORPs is determined both by their differential lipid exchange modes and by privileged localization at the ER/PM subdomains. These findings reveal a role of PtdSer as a signaling lipid that controls the available PM PI(4)P, the unappreciated role of ER PtdSer in cell function, and the diversity of the ER/PM junctions. The effect of PtdSer on the junctional PI(4)P level should have multiple implications in cellular signaling and functions.
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Affiliation(s)
- Woo Young Chung
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Malini Ahuja
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Beth A. McNally
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Spencer R. Leibow
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Henry K. E. Ohman
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Ava Movahed Abtahi
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
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7
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Sperrhacke M, Leitzke S, Ahrens B, Reiss K. Breakdown of Phospholipid Asymmetry Triggers ADAM17-Mediated Rescue Events in Cells Undergoing Apoptosis. MEMBRANES 2023; 13:720. [PMID: 37623781 PMCID: PMC10456294 DOI: 10.3390/membranes13080720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/27/2023] [Accepted: 08/03/2023] [Indexed: 08/26/2023]
Abstract
ADAM17, a prominent member of the "Disintegrin and Metalloproteinase" (ADAM) family, controls vital cellular functions through the cleavage of transmembrane substrates, including epidermal growth factor receptor (EGFR) ligands such as transforming growth factor (TGF)-alpha and Epiregulin (EREG). Several ADAM17 substrates are relevant to oncogenesis and tumor growth. We have presented evidence that surface exposure of phosphatidylserine (PS) is pivotal for ADAM17 to exert sheddase activity. The scramblase Xkr8 is instrumental for calcium-independent exposure of PS in apoptotic cells. Xkr8 can be dually activated by caspase-3 and by kinases. In this investigation, we examined whether Xkr8 would modulate ADAM17 activity under apoptotic and non-apoptotic conditions. Overexpression of Xkr8 in HEK293T cells led to significantly increased caspase-dependent as well as PMA-induced release of EREG and TGF-alpha. Conversely, siRNA-mediated downregulation of Xkr8 in colorectal Caco-2 cancer cells led to decreased PS externalization upon induction of apoptosis, which was accompanied by reduced shedding of endogenously expressed EREG and reduced cell survival. We conclude that Xkr8 shares with conventional scramblases the propensity to upmodulate the ADAM-sheddase function. Liberation of growth factors could serve a rescue function in cells on the pathway to apoptotic death.
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Affiliation(s)
| | | | | | - Karina Reiss
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany (B.A.)
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8
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Fuggetta N, Rigolli N, Magdeleine M, Seminara A, Drin G. Reconstitution of ORP-mediated lipid exchange process coupled to PI(4)P metabolism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.04.551917. [PMID: 37577629 PMCID: PMC10418177 DOI: 10.1101/2023.08.04.551917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Lipid distribution in the eukaryotic cells depends on tight couplings between lipid transfer and lipid metabolism. Yet these couplings remain poorly described. Notably, it is unclear to what extent lipid exchangers of the OSBP-related proteins (ORPs) family, coupled to PI(4)P metabolism, contribute to the formation of sterol and phosphatidylserine gradient between the endoplasmic reticulum (ER) and other cell regions. To address this question, we have examined in vitro the activity of Osh4p, a representative ORP, between Golgi mimetic membranes in which PI(4)P is produced by a PI 4-kinase and ER mimetic membranes in which PI(4)P is hydrolyzed by the phosphatase Sac1p. Using quantitative, real-time assays, we demonstrate that Osh4p creates a sterol gradient between the two membranes by sterol/PI(4)P exchange as soon as a PI(4)P gradient is generated at this interface following ATP addition, and define how much PI(4)P must be synthesized for this process. Then, using a kinetic model supported by our in vitro data, we estimate to what extent PI(4)P metabolism can drive lipid transfer in cells. Finally, we show that Sec14p, by transferring phosphatidylinositol between membranes, can support the synthesis of PI(4)P and the creation of a sterol gradient by Osh4p. These results indicate to what extent ORPs, under the control of PI(4)P metabolism, can distribute lipids in the cell.
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Affiliation(s)
- 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
| | - Nicola Rigolli
- Laboratoire de Physique, École Normale Supérieure (LPENS), 75005 Paris, 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
| | - Agnese Seminara
- Malga, Department of Civil, Chemical and Environmental Engineering, University of Genoa, Villa Cambiaso 1, 16145 Genoa, Italy
| | - 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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Takasugi N, Komai M, Kaneshiro N, Ikeda A, Kamikubo Y, Uehara T. The Pursuit of the "Inside" of the Amyloid Hypothesis-Is C99 a Promising Therapeutic Target for Alzheimer's Disease? Cells 2023; 12:454. [PMID: 36766796 PMCID: PMC9914381 DOI: 10.3390/cells12030454] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 02/04/2023] Open
Abstract
Aducanumab, co-developed by Eisai (Japan) and Biogen (U.S.), has received Food and Drug Administration approval for treating Alzheimer's disease (AD). In addition, its successor antibody, lecanemab, has been approved. These antibodies target the aggregated form of the small peptide, amyloid-β (Aβ), which accumulates in the patient brain. The "amyloid hypothesis" based therapy that places the aggregation and toxicity of Aβ at the center of the etiology is about to be realized. However, the effects of immunotherapy are still limited, suggesting the need to reconsider this hypothesis. Aβ is produced from a type-I transmembrane protein, Aβ precursor protein (APP). One of the APP metabolites, the 99-amino acids C-terminal fragment (C99, also called βCTF), is a direct precursor of Aβ and accumulates in the AD patient's brain to demonstrate toxicity independent of Aβ. Conventional drug discovery strategies have focused on Aβ toxicity on the "outside" of the neuron, but C99 accumulation might explain the toxicity on the "inside" of the neuron, which was overlooked in the hypothesis. Furthermore, the common region of C99 and Aβ is a promising target for multifunctional AD drugs. This review aimed to outline the nature, metabolism, and impact of C99 on AD pathogenesis and discuss whether it could be a therapeutic target complementing the amyloid hypothesis.
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Affiliation(s)
- Nobumasa Takasugi
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, 2-1-1 Hongo Bunkyo-ku, Tokyo 113-8421, Japan
| | - Masato Komai
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Nanaka Kaneshiro
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
- Center for RNA Biology and Medicine, University of California, Riverside, CA 92521, USA
| | - Atsuya Ikeda
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Yuji Kamikubo
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, 2-1-1 Hongo Bunkyo-ku, Tokyo 113-8421, Japan
| | - Takashi Uehara
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
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Peikert K, Danek A. VPS13 Forum Proceedings: XK, XK-Related and VPS13 Proteins in Membrane Lipid Dynamics. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2023; 6:25152564231156994. [PMID: 37366410 PMCID: PMC10243564 DOI: 10.1177/25152564231156994] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 01/23/2023] [Indexed: 06/28/2023]
Abstract
In 2020, the pandemic interrupted the series of biannual International Neuroacanthocytosis Meetings that brought together clinicians, scientists, and patient groups to share research into a small group of devastating genetic diseases that combine both acanthocytosis (deformed red blood cells) and neurodegeneration with movement disorders. This Meeting Report describes talks at the 5th VPS13 Forum in January 2022, one of a series of online meetings held to fill the gap. The meeting addressed the basic biology of two key proteins implicated in chorea-acanthocytosis (mutations in VPS13A) and McLeod syndrome (mutations in XK). In a remarkable confluence of ideas, the speakers described different aspects of a single functional unit that comprises of VPS13A and XK proteins working together. Conditions caused by VPS13 (A-D) gene family mutations and related genes, such as XK, previously footnote knowledge, seem to turn central for a novel disease paradigm: bulk lipid transfer disorders.
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Affiliation(s)
- Kevin Peikert
- Translational Neurodegeneration Section
“Albrecht-Kossel”, Department of Neurology, University Medical Center Rostock, University of
Rostock, Rostock, Germany
- Center for Transdisciplinary Neurosciences
Rostock (CTNR), University Medical Center Rostock, Rostock, Germany
- United Neuroscience Campus Lund-Rostock
(UNC), Rostock site, Rostock, Germany
| | - Adrian Danek
- Department of Neurology, University Hospital,
LMU Munich, Munich, Germany
- German Center for Neurodegenerative Diseases
(Deutsches Zentrum für Neurodegenerative Erkrankungen, DZNE), Research Site Munich, Munich,
Germany
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11
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Basante-Bedoya MA, Bogliolo S, Garcia-Rodas R, Zaragoza O, Arkowitz RA, Bassilana M. Two distinct lipid transporters together regulate invasive filamentous growth in the human fungal pathogen Candida albicans. PLoS Genet 2022; 18:e1010549. [PMID: 36516161 PMCID: PMC9797089 DOI: 10.1371/journal.pgen.1010549] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 12/28/2022] [Accepted: 11/29/2022] [Indexed: 12/15/2022] Open
Abstract
Flippases transport lipids across the membrane bilayer to generate and maintain asymmetry. The human fungal pathogen Candida albicans has 5 flippases, including Drs2, which is critical for filamentous growth and phosphatidylserine (PS) distribution. Furthermore, a drs2 deletion mutant is hypersensitive to the antifungal drug fluconazole and copper ions. We show here that such a flippase mutant also has an altered distribution of phosphatidylinositol 4-phosphate [PI(4)P] and ergosterol. Analyses of additional lipid transporters, i.e. the flippases Dnf1-3, and all the oxysterol binding protein (Osh) family lipid transfer proteins, i.e. Osh2-4 and Osh7, indicate that they are not critical for filamentous growth. However, deletion of Osh4 alone, which exchanges PI(4)P for sterol, in a drs2 mutant can bypass the requirement for this flippase in invasive filamentous growth. In addition, deletion of the lipid phosphatase Sac1, which dephosphorylates PI(4)P, in a drs2 mutant results in a synthetic growth defect, suggesting that Drs2 and Sac1 function in parallel pathways. Together, our results indicate that a balance between the activities of two putative lipid transporters regulates invasive filamentous growth, via PI(4)P. In contrast, deletion of OSH4 in drs2 does not restore growth on fluconazole, nor on papuamide A, a toxin that binds PS in the outer leaflet of the plasma membrane, suggesting that Drs2 has additional role(s) in plasma membrane organization, independent of Osh4. As we show that C. albicans Drs2 localizes to different structures, including the Spitzenkörper, we investigated if a specific localization of Drs2 is critical for different functions, using a synthetic physical interaction approach to restrict/stabilize Drs2 at the Spitzenkörper. Our results suggest that the localization of Drs2 at the plasma membrane is critical for C. albicans growth on fluconazole and papuamide A, but not for invasive filamentous growth.
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Affiliation(s)
| | | | - Rocio Garcia-Rodas
- Université Côte d’Azur, CNRS, INSERM, iBV, Parc Valrose, Nice, FRANCE
- Mycology Reference Laboratory, National Centre for Microbiology, Health Institute Carlos III, Majadahonda, Madrid, Spain
| | - Oscar Zaragoza
- Mycology Reference Laboratory, National Centre for Microbiology, Health Institute Carlos III, Majadahonda, Madrid, Spain
- Center for Biomedical Research in Network in Infectious Diseases (CIBERINFEC-CB21/13/00105), Health Institute Carlos III, Madrid, Spain
| | | | - Martine Bassilana
- Université Côte d’Azur, CNRS, INSERM, iBV, Parc Valrose, Nice, FRANCE
- * E-mail:
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12
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Creating and sensing asymmetric lipid distributions throughout the cell. Emerg Top Life Sci 2022; 7:7-19. [PMID: 36373850 DOI: 10.1042/etls20220028] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/24/2022] [Accepted: 11/01/2022] [Indexed: 11/16/2022]
Abstract
A key feature of eukaryotic cells is the asymmetric distribution of lipids along their secretory pathway. Because of the biological significance of these asymmetries, it is crucial to define the mechanisms which create them. Extensive studies have led to the identification of lipid transfer proteins (LTPs) that work with lipid-synthesizing enzymes to carry lipids between two distinct membranes in a directional manner, and are thus able to create asymmetries in lipid distribution throughout the cell. These networks are often in contact sites where two organelle membranes are in close proximity for reasons we have only recently started to understand. A question is whether these networks transfer lipids en masse within the cells or adjust the lipid composition of organelle membranes. Finally, recent data have confirmed that some networks organized around LTPs do not generate lipid asymmetries between membranes but sense them and rectify the lipid content of the cell.
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13
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Miyata Y, Yamada K, Nagata S, Segawa K. Two types of type IV P-type ATPases independently re-establish the asymmetrical distribution of phosphatidylserine in plasma membranes. J Biol Chem 2022; 298:102527. [PMID: 36162506 PMCID: PMC9597894 DOI: 10.1016/j.jbc.2022.102527] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 09/15/2022] [Accepted: 09/19/2022] [Indexed: 11/21/2022] Open
Abstract
Phospholipids are asymmetrically distributed between the lipid bilayer of plasma membranes in which phosphatidylserine (PtdSer) is confined to the inner leaflet. ATP11A and ATP11C, type IV P-Type ATPases in plasma membranes, flip PtdSer from the outer to the inner leaflet, but involvement of other P4-ATPases is unclear. We herein demonstrated that once PtdSer was exposed on the cell surface of ATP11A−/−ATP11C−/− mouse T cell line (W3), its internalization to the inner leaflet of plasma membranes was negligible at 15 °C. However, ATP11A−/−ATP11C−/− cells internalized the exposed PtdSer at 37 °C, a temperature at which trafficking of intracellular membranes was active. In addition to ATP11A and 11C, W3 cells expressed ATP8A1, 8B2, 8B4, 9A, 9B, and 11B, with ATP8A1 and ATP11B being present at recycling endosomes. Cells deficient in four P4-ATPases (ATP8A1, 11A, 11B, and 11C) (QKO) did not constitutively expose PtdSer on the cell surface but lost the ability to re-establish PtdSer asymmetry within 1 hour, even at 37 °C. The expression of ATP11A or ATP11C conferred QKO cells with the ability to rapidly re-establish PtdSer asymmetry at 15 °C and 37 °C, while cells expressing ATP8A1 or ATP11B required a temperature of 37 °C to achieve this function, and a dynamin inhibitor blocked this process. These results revealed that mammalian cells are equipped with two independent mechanisms to re-establish its asymmetry: the first is a rapid process involving plasma membrane flippases, ATP11A and ATP11C, while the other is mediated by ATP8A1 and ATP11B, which require an endocytosis process.
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Affiliation(s)
- Yugo Miyata
- Department of Medical Chemistry, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
| | - Kyoko Yamada
- Laboratory of Biochemistry & Immunology, World Premier International Research Center, Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan
| | - Shigekazu Nagata
- Laboratory of Biochemistry & Immunology, World Premier International Research Center, Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan.
| | - Katsumori Segawa
- Department of Medical Chemistry, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan; Laboratory of Biochemistry & Immunology, World Premier International Research Center, Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan.
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14
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Pryzdial ELG, Leatherdale A, Conway EM. Coagulation and complement: Key innate defense participants in a seamless web. Front Immunol 2022; 13:918775. [PMID: 36016942 PMCID: PMC9398469 DOI: 10.3389/fimmu.2022.918775] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/06/2022] [Indexed: 12/30/2022] Open
Abstract
In 1969, Dr. Oscar Ratnoff, a pioneer in delineating the mechanisms by which coagulation is activated and complement is regulated, wrote, “In the study of biological processes, the accumulation of information is often accelerated by a narrow point of view. The fastest way to investigate the body’s defenses against injury is to look individually at such isolated questions as how the blood clots or how complement works. We must constantly remind ourselves that such distinctions are man-made. In life, as in the legal cliché, the devices through which the body protects itself form a seamless web, unwrinkled by our artificialities.” Our aim in this review, is to highlight the critical molecular and cellular interactions between coagulation and complement, and how these two major component proteolytic pathways contribute to the seamless web of innate mechanisms that the body uses to protect itself from injury, invading pathogens and foreign surfaces.
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Affiliation(s)
- Edward L. G. Pryzdial
- Centre for Blood Research, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Canadian Blood Services, Medical Affairs and Innovation, Vancouver, BC, Canada
- *Correspondence: Edward L. G. Pryzdial, ; Edward M. Conway,
| | - Alexander Leatherdale
- Centre for Blood Research, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
- Division of Hematology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Edward M. Conway
- Centre for Blood Research, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
- Canadian Blood Services, Medical Affairs and Innovation, Vancouver, BC, Canada
- Division of Hematology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
- *Correspondence: Edward L. G. Pryzdial, ; Edward M. Conway,
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15
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Nomura W, Ng SP, Takahara T, Maeda T, Kawada T, Goto T, Inoue Y. Roles of phosphatidylserine and phospholipase C in the activation of TOR complex 2 signaling in Saccharomyces cerevisiae. J Cell Sci 2022; 135:276172. [PMID: 35912799 DOI: 10.1242/jcs.259988] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 07/22/2022] [Indexed: 11/20/2022] Open
Abstract
The target of rapamycin (TOR) forms two distinct complexes, TORC1 and TORC2, to exert its functions essential for cellular growth and homeostasis. TORC1 signaling is regulated in response to nutrients such as amino acids and glucose; however, the mechanisms underlying the activation of TORC2 signaling are still poorly understood compared to TORC1 signaling. In the budding yeast Saccharomyces cerevisiae, TORC2 targets protein kinases Ypk1, Ypk2, and Pkc1 for phosphorylation. Plasma membrane stress is known to activate the TORC2-Ypk1/2 signaling. We have previously reported that methylglyoxal (MG), a metabolite derived from glycolysis, activates TORC2-Pkc1 signaling. In this study, we found that MG activates the TORC2-Ypk1/2 and TORC2-Pkc1 signaling, and that phosphatidylserine is involved in the activation of both signaling pathways. We also demonstrated that the Rho-family GTPase Cdc42 contributes to the plasma membrane stress-induced activation of TORC2-Ypk1/2 signaling. Furthermore, we revealed that phosphatidylinositol-specific phospholipase C, Plc1, contributes to the activation of both TORC2-Ypk1/2 and TORC2-Pkc1 signaling.
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Affiliation(s)
- Wataru Nomura
- Laboratory of Molecular Microbiology, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Su-Ping Ng
- Laboratory of Molecular Functions of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Terunao Takahara
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan
| | - Tatsuya Maeda
- Department of Biology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Teruo Kawada
- Laboratory of Molecular Functions of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Tsuyoshi Goto
- Laboratory of Molecular Functions of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Yoshiharu Inoue
- Laboratory of Molecular Microbiology, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
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16
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Chen S, Huang Y, Su H, Zhu W, Wei Y, Long Y, Shi Y, Wei J. The Integrated Analysis of Transcriptomics and Metabolomics Unveils the Therapeutical Effect of Asiatic Acid on Alcoholic Hepatitis in Rats. Inflammation 2022; 45:1780-1799. [DOI: 10.1007/s10753-022-01660-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 03/10/2022] [Accepted: 03/10/2022] [Indexed: 11/24/2022]
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17
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Need for more focus on lipid species in studies of biological and model membranes. Prog Lipid Res 2022; 86:101160. [DOI: 10.1016/j.plipres.2022.101160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 03/06/2022] [Indexed: 11/23/2022]
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18
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Scramblases as Regulators of Proteolytic ADAM Function. MEMBRANES 2022; 12:membranes12020185. [PMID: 35207106 PMCID: PMC8880048 DOI: 10.3390/membranes12020185] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/25/2022] [Accepted: 02/02/2022] [Indexed: 11/16/2022]
Abstract
Proteolytic ectodomain release is a key mechanism for regulating the function of many cell surface proteins. The sheddases ADAM10 and ADAM17 are the best-characterized members of the family of transmembrane disintegrin-like metalloproteinase. Constitutive proteolytic activities are low but can be abruptly upregulated via inside-out signaling triggered by diverse activating events. Emerging evidence indicates that the plasma membrane itself must be assigned a dominant role in upregulation of sheddase function. Data are discussed that tentatively identify phospholipid scramblases as central players during these events. We propose that scramblase-dependent externalization of the negatively charged phospholipid phosphatidylserine (PS) plays an important role in the final activation step of ADAM10 and ADAM17. In this manuscript, we summarize the current knowledge on the interplay of cell membrane changes, PS exposure, and proteolytic activity of transmembrane proteases as well as the potential consequences in the context of immune response, infection, and cancer. The novel concept that scramblases regulate the action of ADAM-proteases may be extendable to other functional proteins that act at the cell surface.
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19
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Bugda Gwilt K, Thiagarajah JR. Membrane Lipids in Epithelial Polarity: Sorting out the PIPs. Front Cell Dev Biol 2022; 10:893960. [PMID: 35712665 PMCID: PMC9197455 DOI: 10.3389/fcell.2022.893960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/04/2022] [Indexed: 11/13/2022] Open
Abstract
The development of cell polarity in epithelia, is critical for tissue morphogenesis and vectorial transport between the environment and the underlying tissue. Epithelial polarity is defined by the development of distinct plasma membrane domains: the apical membrane interfacing with the exterior lumen compartment, and the basolateral membrane directly contacting the underlying tissue. The de novo generation of polarity is a tightly regulated process, both spatially and temporally, involving changes in the distribution of plasma membrane lipids, localization of apical and basolateral membrane proteins, and vesicular trafficking. Historically, the process of epithelial polarity has been primarily described in relation to the localization and function of protein 'polarity complexes.' However, a critical and foundational role is emerging for plasma membrane lipids, and in particular phosphoinositide species. Here, we broadly review the evidence for a primary role for membrane lipids in the generation of epithelial polarity and highlight key areas requiring further research. We discuss the complex interchange that exists between lipid species and briefly examine how major membrane lipid constituents are generated and intersect with vesicular trafficking to be preferentially localized to different membrane domains with a focus on some of the key protein-enzyme complexes involved in these processes.
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Affiliation(s)
- Katlynn Bugda Gwilt
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
| | - Jay R Thiagarajah
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
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20
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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: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [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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