101
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The emerging roles of OSBP-related proteins in cancer: Impacts through phosphoinositide metabolism and protein-protein interactions. Biochem Pharmacol 2021; 196:114455. [PMID: 33556339 DOI: 10.1016/j.bcp.2021.114455] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 01/26/2021] [Accepted: 01/28/2021] [Indexed: 01/04/2023]
Abstract
Oxysterol-binding protein -related proteins (ORPs) form a large family of intracellular lipid binding/transfer proteins. A number of ORPs are implicated in inter-organelle lipid transfer over membrane contacts sites, their mode of action involving in several cases the transfer of two lipids in opposite directions, termed countercurrent lipid transfer. A unifying feature appears to be the capacity to bind phosphatidylinositol polyphosphates (PIPs). These lipids are in some cases transported by ORPs from one organelle to another to drive the transfer of another lipid against its concentration gradient, while they in other cases may act as allosteric regulators of ORPs, or an ORP may introduce a PIP to an enzyme for catalysis. Dysregulation of several ORP family members is implicated in cancers, ORP3, -4, -5 and -8 being thus far the most studied examples. The most likely mechanisms underlying their associations with malignant growth are (i) impacts on PIP-mediated signaling events resulting in altered Ca2+ homeostasis, bioenergetics, cell survival, proliferation, and migration, (ii) protein-protein interactions affecting the activity of signaling factors, and (iii) modification of cellular lipid transport in a way that facilitates the proliferation of malignant cells. In this review I discuss the existing functional evidence for the involvement of ORPs in cancerous growth, discuss the findings in the light of the putative mechanisms outlined above and the possibility of employing ORPs as targets of anti-cancer therapy.
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102
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Montaño-Rendón F, Grinstein S, Walpole GFW. Monitoring Phosphoinositide Fluxes and Effectors During Leukocyte Chemotaxis and Phagocytosis. Front Cell Dev Biol 2021; 9:626136. [PMID: 33614656 PMCID: PMC7890364 DOI: 10.3389/fcell.2021.626136] [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: 11/04/2020] [Accepted: 01/06/2021] [Indexed: 01/22/2023] Open
Abstract
The dynamic re-organization of cellular membranes in response to extracellular stimuli is fundamental to the cell physiology of myeloid and lymphoid cells of the immune system. In addition to maintaining cellular homeostatic functions, remodeling of the plasmalemma and endomembranes endow leukocytes with the potential to relay extracellular signals across their biological membranes to promote rolling adhesion and diapedesis, migration into the tissue parenchyma, and to ingest foreign particles and effete cells. Phosphoinositides, signaling lipids that control the interface of biological membranes with the external environment, are pivotal to this wealth of functions. Here, we highlight the complex metabolic transitions that occur to phosphoinositides during several stages of the leukocyte lifecycle, namely diapedesis, migration, and phagocytosis. We describe classical and recently developed tools that have aided our understanding of these complex lipids. Finally, major downstream effectors of inositides are highlighted including the cytoskeleton, emphasizing the importance of these rare lipids in immunity and disease.
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Affiliation(s)
- Fernando Montaño-Rendón
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada
| | - Glenn F W Walpole
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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103
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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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104
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A Real-Time Phosphatidylinositol 4-Phosphate 5-Kinase Assay Using Fluorescence Spectroscopy. Methods Mol Biol 2021. [PMID: 33481235 DOI: 10.1007/978-1-0716-1142-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Phosphatidylinositol 4-phosphate 5-kinase (PIP5K) is an enzyme that converts phosphatidylinositol 4-phosphate [PI4P] to phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. PIP5K plays a key role in the regulation of vesicular transport, cytoskeleton reorganization, and cell division. In general, to investigate an enzymatic activity of PIP5K, the amount of incorporated [P32] ATP into PI(4,5)P2 fraction is measured in in vitro reconstitution experiments. However, tools to monitor dynamic changes in its activity in real time have been lacking. Recently, we have developed a novel PIP5K assay using fluorescence spectroscopy. Compared to conventional methods in which lipids extraction steps are needed, our method is easy and quick to perform and enables a real-time analysis. This chapter provides a protocol to set up and perform the novel PIP5K assay we have recently established.
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105
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David Y, Castro IG, Schuldiner M. The Fast and the Furious: Golgi Contact Sites. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2021; 4:1-15. [PMID: 35071979 PMCID: PMC7612241 DOI: 10.1177/25152564211034424] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Contact sites are areas of close apposition between two membranes that coordinate nonvesicular communication between organelles. Such interactions serve a wide range of cellular functions from regulating metabolic pathways to executing stress responses and coordinating organelle inheritance. The past decade has seen a dramatic increase in information on certain contact sites, mostly those involving the endoplasmic reticulum. However, despite its central role in the secretory pathway, the Golgi apparatus and its contact sites remain largely unexplored. In this review, we discuss the current knowledge of Golgi contact sites and share our thoughts as to why Golgi contact sites are understudied. We also highlight what exciting future directions may exist in this emerging field.
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Affiliation(s)
- Yotam David
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Inês G Castro
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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106
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Xu J, Huang X. Lipid Metabolism at Membrane Contacts: Dynamics and Functions Beyond Lipid Homeostasis. Front Cell Dev Biol 2020; 8:615856. [PMID: 33425923 PMCID: PMC7786193 DOI: 10.3389/fcell.2020.615856] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 11/30/2020] [Indexed: 01/12/2023] Open
Abstract
Membrane contact sites (MCSs), regions where the membranes of two organelles are closely apposed, play critical roles in inter-organelle communication, such as lipid trafficking, intracellular signaling, and organelle biogenesis and division. First identified as “fraction X” in the early 90s, MCSs are now widely recognized to facilitate local lipid synthesis and inter-organelle lipid transfer, which are important for maintaining cellular lipid homeostasis. In this review, we discuss lipid metabolism and related cellular and physiological functions in MCSs. We start with the characteristics of lipid synthesis and breakdown at MCSs. Then we focus on proteins involved in lipid synthesis and turnover at these sites. Lastly, we summarize the cellular function of lipid metabolism at MCSs beyond mere lipid homeostasis, including the physiological meaning and relevance of MCSs regarding systemic lipid metabolism. This article is part of an article collection entitled: Coupling and Uncoupling: Dynamic Control of Membrane Contacts.
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Affiliation(s)
- Jiesi Xu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China.,College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
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107
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Sajko S, Grishkovskaya I, Kostan J, Graewert M, Setiawan K, Trübestein L, Niedermüller K, Gehin C, Sponga A, Puchinger M, Gavin AC, Leonard TA, Svergun DI, Smith TK, Morriswood B, Djinovic-Carugo K. Structures of three MORN repeat proteins and a re-evaluation of the proposed lipid-binding properties of MORN repeats. PLoS One 2020; 15:e0242677. [PMID: 33296386 PMCID: PMC7725318 DOI: 10.1371/journal.pone.0242677] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/08/2020] [Indexed: 11/19/2022] Open
Abstract
MORN (Membrane Occupation and Recognition Nexus) repeat proteins have a wide taxonomic distribution, being found in both prokaryotes and eukaryotes. Despite this ubiquity, they remain poorly characterised at both a structural and a functional level compared to other common repeats. In functional terms, they are often assumed to be lipid-binding modules that mediate membrane targeting. We addressed this putative activity by focusing on a protein composed solely of MORN repeats-Trypanosoma brucei MORN1. Surprisingly, no evidence for binding to membranes or lipid vesicles by TbMORN1 could be obtained either in vivo or in vitro. Conversely, TbMORN1 did interact with individual phospholipids. High- and low-resolution structures of the MORN1 protein from Trypanosoma brucei and homologous proteins from the parasites Toxoplasma gondii and Plasmodium falciparum were obtained using a combination of macromolecular crystallography, small-angle X-ray scattering, and electron microscopy. This enabled a first structure-based definition of the MORN repeat itself. Furthermore, all three structures dimerised via their C-termini in an antiparallel configuration. The dimers could form extended or V-shaped quaternary structures depending on the presence of specific interface residues. This work provides a new perspective on MORN repeats, showing that they are protein-protein interaction modules capable of mediating both dimerisation and oligomerisation.
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Affiliation(s)
- Sara Sajko
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Irina Grishkovskaya
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Julius Kostan
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Melissa Graewert
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Kim Setiawan
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Linda Trübestein
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Korbinian Niedermüller
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Charlotte Gehin
- European Molecular Biology Laboratory, Heidelberg Unit, Heidelberg, Germany
- Institute of Bioengineering, Laboratory of Lipid Cell Biology, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Antonio Sponga
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Martin Puchinger
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Anne-Claude Gavin
- European Molecular Biology Laboratory, Heidelberg Unit, Heidelberg, Germany
- Department for Cell Physiology and Metabolism, University of Geneva, Centre Medical Universitaire, Geneva, Switzerland
| | - Thomas A. Leonard
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | | | - Terry K. Smith
- School of Biology, BSRC, University of St. Andrews, St. Andrews, United Kingdom
| | - Brooke Morriswood
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Kristina Djinovic-Carugo
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
- Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
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108
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Scaffold association factor B (SAFB) is required for expression of prenyltransferases and RAS membrane association. Proc Natl Acad Sci U S A 2020; 117:31914-31922. [PMID: 33257571 DOI: 10.1073/pnas.2005712117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Inhibiting membrane association of RAS has long been considered a rational approach to anticancer therapy, which led to the development of farnesyltransferase inhibitors (FTIs). However, FTIs proved ineffective against KRAS-driven tumors. To reveal alternative therapeutic strategies, we carried out a genome-wide CRISPR-Cas9 screen designed to identify genes required for KRAS4B membrane association. We identified five enzymes in the prenylation pathway and SAFB, a nuclear protein with both DNA and RNA binding domains. Silencing SAFB led to marked mislocalization of all RAS isoforms as well as RAP1A but not RAB7A, a pattern that phenocopied silencing FNTA, the prenyltransferase α subunit shared by farnesyltransferase and geranylgeranyltransferase type I. We found that SAFB promoted RAS membrane association by controlling FNTA expression. SAFB knockdown decreased GTP loading of RAS, abrogated alternative prenylation, and sensitized RAS-mutant cells to growth inhibition by FTI. Our work establishes the prenylation pathway as paramount in KRAS membrane association, reveals a regulator of prenyltransferase expression, and suggests that reduction in FNTA expression may enhance the efficacy of FTIs.
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109
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Luquain-Costaz C, Rabia M, Hullin-Matsuda F, Delton I. Bis(monoacylglycero)phosphate, an important actor in the host endocytic machinery hijacked by SARS-CoV-2 and related viruses. Biochimie 2020; 179:247-256. [PMID: 33159981 PMCID: PMC7642752 DOI: 10.1016/j.biochi.2020.10.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/28/2020] [Accepted: 10/29/2020] [Indexed: 12/12/2022]
Abstract
Viruses, including the novel coronavirus SARS-CoV-2, redirect infected cell metabolism to their own purposes. After binding to its receptor angiotensin-converting enzyme 2 (ACE2) on the cell surface, the SARS-CoV-2 is taken up by receptor-mediated endocytosis ending in the acidic endolysosomal compartment. The virus hijacks the endosomal machinery leading to fusion of viral and endosomal membranes and release of the viral RNA into the cytosol. This mini-review specifically highlights the membrane lipid organization of the endosomal system focusing on the unconventional and late endosome/lysosome-specific phospholipid, bis(monoacylglycero)phosphate (BMP). BMP is enriched in alveolar macrophages of lung, one of the target tissue of SARS-CoV-2. This review details the BMP structure, its unsaturated fatty acid composition and fusogenic properties that are essential for the highly dynamic formation of the intraluminal vesicles inside the endosomes. Interestingly, BMP is necessary for infection and replication of enveloped RNA virus such as SARS-CoV-1 and Dengue virus. We also emphasize the role of BMP in lipid sorting and degradation, especially cholesterol transport in cooperation with Niemann Pick type C proteins (NPC 1 and 2) and with some oxysterol-binding protein (OSBP)-related proteins (ORPs) as well as in sphingolipid degradation. Interestingly, numerous virus infection required NPC1 as well as ORPs along the endocytic pathway. Furthermore, BMP content is increased during pathological endosomal lipid accumulation in various lysosomal storage disorders. This is particularly important knowing the high percentage of patients with metabolic disorders among the SARS-CoV-2 infected patients presenting severe forms of COVID-19.
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Affiliation(s)
- Céline Luquain-Costaz
- Univ-Lyon, CarMeN Laboratory, Inserm U1060, INRAe U1397, INSA Lyon, Villeurbanne, France
| | - Maxence Rabia
- Univ-Lyon, CarMeN Laboratory, Inserm U1060, INRAe U1397, INSA Lyon, Villeurbanne, France
| | | | - Isabelle Delton
- Univ-Lyon, CarMeN Laboratory, Inserm U1060, INRAe U1397, INSA Lyon, Villeurbanne, France.
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110
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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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111
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Kattan WE, Hancock JF. RAS Function in cancer cells: translating membrane biology and biochemistry into new therapeutics. Biochem J 2020; 477:2893-2919. [PMID: 32797215 PMCID: PMC7891675 DOI: 10.1042/bcj20190839] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/20/2020] [Accepted: 07/22/2020] [Indexed: 02/07/2023]
Abstract
The three human RAS proteins are mutated and constitutively activated in ∼20% of cancers leading to cell growth and proliferation. For the past three decades, many attempts have been made to inhibit these proteins with little success. Recently; however, multiple methods have emerged to inhibit KRAS, the most prevalently mutated isoform. These methods and the underlying biology will be discussed in this review with a special focus on KRAS-plasma membrane interactions.
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Affiliation(s)
- Walaa E. Kattan
- Department of Integrative Biology and Pharmacology, McGovern Medical School University of Texas Health Science Center at Houston, TX 77030, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, TX 77030, USA
| | - John F. Hancock
- Department of Integrative Biology and Pharmacology, McGovern Medical School University of Texas Health Science Center at Houston, TX 77030, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, TX 77030, USA
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112
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Dong X, Wang Z, Ye S, Zhang R. The crystal structure of ORP3 reveals the conservative PI4P binding pattern. Biochem Biophys Res Commun 2020; 529:1005-1010. [PMID: 32819557 DOI: 10.1016/j.bbrc.2020.06.090] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 06/18/2020] [Indexed: 10/23/2022]
Abstract
Oxysterol-binding protein (OSBP) and its related protein (ORP) constitute a conserved family of lipid transfer proteins (LTPs). ORPs have been implicated as intracellular lipid exchanger and sensor in recent years, which regulate the lipid homeostasis and signal pathway. OSBP-related protein 3 plays key role in controlling cell adhesion and migration and could be developed as the drug target for cancer therapy. Here, we report the crystal structures of human ORP3 ORD to 2.1 Å and ORD-PI4P complex to 3.2 Å. The binding assay in vitro confirms the ORP3 has the capability of PI4P binding. This study further verifies that the PI4P is the common ligand of all ORPs and ORPs should be the lipid exchanger in membrane contact sites(MCS).
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Affiliation(s)
- Xue Dong
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China.
| | - Zhiming Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Sheng Ye
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Rongguang Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China.
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113
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Du X, Zhou L, Aw YC, Mak HY, Xu Y, Rae J, Wang W, Zadoorian A, Hancock SE, Osborne B, Chen X, Wu JW, Turner N, Parton RG, Li P, Yang H. ORP5 localizes to ER-lipid droplet contacts and regulates the level of PI(4)P on lipid droplets. J Cell Biol 2020; 219:jcb.201905162. [PMID: 31653673 PMCID: PMC7039201 DOI: 10.1083/jcb.201905162] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 09/17/2019] [Accepted: 10/03/2019] [Indexed: 12/22/2022] Open
Abstract
Lipid droplets (LDs) are important organelles for cell metabolism. Here, Du et al. show that phosphatidylinositol-4-phosphate produced by PI4K2A can exist on LDs and is used/consumed by ORP5, which localizes to ER–LD contacts during the growth of LDs. Lipid droplets (LDs) are evolutionarily conserved organelles that play important roles in cellular metabolism. Each LD is enclosed by a monolayer of phospholipids, distinct from bilayer membranes. During LD biogenesis and growth, this monolayer of lipids expands by acquiring phospholipids from the endoplasmic reticulum (ER) through nonvesicular mechanisms. Here, in a mini-screen, we find that ORP5, an integral membrane protein of the ER, can localize to ER–LD contact sites upon oleate loading. ORP5 interacts with LDs through its ligand-binding domain, and ORP5 deficiency enhances neutral lipid synthesis and increases the size of LDs. Importantly, there is significantly more phosphatidylinositol-4-phosphate (PI(4)P) and less phosphatidylserine (PS) on LDs in ORP5-deficient cells than in normal cells. The increased presence of PI(4)P on LDs in ORP5-deficient cells requires phosphatidylinositol 4-kinase 2-α. Our results thus demonstrate the existence of PI(4)P on LDs and suggest that LD-associated PI(4)P may be primarily used by ORP5 to deliver PS to LDs.
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Affiliation(s)
- Ximing Du
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - Linkang Zhou
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yvette Celine Aw
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - Hoi Yin Mak
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - Yanqing Xu
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - James Rae
- Centre for Microscopy and Microanalysis, Institute of Molecular Bioscience, University of Queensland, St. Lucia, Australia
| | - Wenmin Wang
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Armella Zadoorian
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - Sarah E Hancock
- School of Medical Sciences, The University of New South Wales, Sydney, Australia
| | - Brenna Osborne
- School of Medical Sciences, The University of New South Wales, Sydney, Australia
| | - Xiang Chen
- Institute of Molecular Enzymology, Soochow University, Suzhou, Jiangsu, China
| | - Jia-Wei Wu
- Institute of Molecular Enzymology, Soochow University, Suzhou, Jiangsu, China
| | - Nigel Turner
- School of Medical Sciences, The University of New South Wales, Sydney, Australia
| | - Robert G Parton
- Centre for Microscopy and Microanalysis, Institute of Molecular Bioscience, University of Queensland, St. Lucia, Australia
| | - Peng Li
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
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114
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Chang W, Fa H, Xiao D, Wang J. Targeting phosphatidylserine for Cancer therapy: prospects and challenges. Theranostics 2020; 10:9214-9229. [PMID: 32802188 PMCID: PMC7415799 DOI: 10.7150/thno.45125] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 07/13/2020] [Indexed: 02/06/2023] Open
Abstract
Cancer is a leading cause of mortality and morbidity worldwide. Despite major improvements in current therapeutic methods, ideal therapeutic strategies for improved tumor elimination are still lacking. Recently, immunotherapy has attracted much attention, and many immune-active agents have been approved for clinical use alone or in combination with other cancer drugs. However, some patients have a poor response to these agents. New agents and strategies are needed to overcome such deficiencies. Phosphatidylserine (PS) is an essential component of bilayer cell membranes and is normally present in the inner leaflet. In the physiological state, PS exposure on the external leaflet not only acts as an engulfment signal for phagocytosis in apoptotic cells but also participates in blood coagulation, myoblast fusion and immune regulation in nonapoptotic cells. In the tumor microenvironment, PS exposure is significantly increased on the surface of tumor cells or tumor cell-derived microvesicles, which have innate immunosuppressive properties and facilitate tumor growth and metastasis. To date, agents targeting PS have been developed, some of which are under investigation in clinical trials as combination drugs for various cancers. However, controversial results are emerging in laboratory research as well as in clinical trials, and the efficiency of PS-targeting agents remains uncertain. In this review, we summarize recent progress in our understanding of the physiological and pathological roles of PS, with a focus on immune suppressive features. In addition, we discuss current drug developments that are based on PS-targeting strategies in both experimental and clinical studies. We hope to provide a future research direction for the development of new agents for cancer therapy.
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Affiliation(s)
- Wenguang Chang
- Institute for Translational Medicine, The Affiliated Hospital, College of medicine, Qingdao University, Qingdao, China
| | - Hongge Fa
- Institute for Translational Medicine, The Affiliated Hospital, College of medicine, Qingdao University, Qingdao, China
- School of Basic Medical Sciences, College of medicine, Qingdao University, Qingdao, China
| | - Dandan Xiao
- Institute for Translational Medicine, The Affiliated Hospital, College of medicine, Qingdao University, Qingdao, China
- School of Basic Medical Sciences, College of medicine, Qingdao University, Qingdao, China
| | - Jianxun Wang
- School of Basic Medical Sciences, College of medicine, Qingdao University, Qingdao, China
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115
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Silva BSC, DiGiovanni L, Kumar R, Carmichael RE, Kim PK, Schrader M. Maintaining social contacts: The physiological relevance of organelle interactions. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118800. [PMID: 32712071 PMCID: PMC7377706 DOI: 10.1016/j.bbamcr.2020.118800] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/12/2020] [Accepted: 07/19/2020] [Indexed: 02/07/2023]
Abstract
Membrane-bound organelles in eukaryotic cells form an interactive network to coordinate and facilitate cellular functions. The formation of close contacts, termed "membrane contact sites" (MCSs), represents an intriguing strategy for organelle interaction and coordinated interplay. Emerging research is rapidly revealing new details of MCSs. They represent ubiquitous and diverse structures, which are important for many aspects of cell physiology and homeostasis. Here, we provide a comprehensive overview of the physiological relevance of organelle contacts. We focus on mitochondria, peroxisomes, the Golgi complex and the plasma membrane, and discuss the most recent findings on their interactions with other subcellular organelles and their multiple functions, including membrane contacts with the ER, lipid droplets and the endosomal/lysosomal compartment.
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Affiliation(s)
- Beatriz S C Silva
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Laura DiGiovanni
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Rechal Kumar
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Ruth E Carmichael
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK.
| | - Peter K Kim
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
| | - Michael Schrader
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK.
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116
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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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117
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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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118
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Bohnert M. Tether Me, Tether Me Not—Dynamic Organelle Contact Sites in Metabolic Rewiring. Dev Cell 2020; 54:212-225. [DOI: 10.1016/j.devcel.2020.06.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/17/2020] [Accepted: 06/20/2020] [Indexed: 02/04/2023]
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119
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ORP5 and ORP8: Sterol Sensors and Phospholipid Transfer Proteins at Membrane Contact Sites? Biomolecules 2020; 10:biom10060928. [PMID: 32570981 PMCID: PMC7356933 DOI: 10.3390/biom10060928] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/13/2020] [Accepted: 06/16/2020] [Indexed: 02/07/2023] Open
Abstract
Oxysterol binding related proteins 5 and 8 (ORP5 and ORP8) are two close homologs of the larger oxysterol binding protein (OSBP) family of sterol sensors and lipid transfer proteins (LTP). Early studies indicated these transmembrane proteins, anchored to the endoplasmic reticulum (ER), bound and sensed cholesterol and oxysterols. They were identified as important for diverse cellular functions including sterol homeostasis, vesicular trafficking, proliferation and migration. In addition, they were implicated in lipid-related diseases such as atherosclerosis and diabetes, but also cancer, although their mechanisms of action remained poorly understood. Then, alongside the increasing recognition that membrane contact sites (MCS) serve as hubs for non-vesicular lipid transfer, added to their structural similarity to other LTPs, came discoveries showing that ORP5 and 8 were in fact phospholipid transfer proteins that rather sense and exchange phosphatidylserine (PS) for phosphoinositides, including phosphatidylinositol-4-phosphate (PI(4)P) and potentially phosphatidylinositol-(4,5)-bisphosphate (PI(4,5)P2). Evidence now points to their action at MCS between the ER and various organelles including the plasma membrane, lysosomes, mitochondria, and lipid droplets. Dissecting exactly how this unexpected phospholipid transfer function connects with sterol regulation in health or disease remains a challenge for future studies.
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120
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D'Ambrosio JM, Albanèse V, Lipp NF, Fleuriot L, Debayle D, Drin G, Čopič A. Osh6 requires Ist2 for localization to ER-PM contacts and efficient phosphatidylserine transport in budding yeast. J Cell Sci 2020; 133:jcs.243733. [PMID: 32327560 DOI: 10.1242/jcs.243733] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 04/06/2020] [Indexed: 11/20/2022] Open
Abstract
Osh6 and Osh7 are lipid transfer proteins (LTPs) that move phosphatidylserine (PS) from the endoplasmic reticulum (ER) to the plasma membrane (PM). High PS levels at the PM are key for many cellular functions. Intriguingly, Osh6 and Osh7 localize to ER-PM contact sites, although they lack membrane-targeting motifs, in contrast to multidomain LTPs that both bridge membranes and convey lipids. We show that Osh6 localization to contact sites depends on its interaction with the cytosolic tail of the ER-PM tether Ist2, a homolog of TMEM16 proteins. We identify a motif in the Ist2 tail, conserved in yeasts, as the Osh6-binding region, and we map an Ist2-binding surface on Osh6. Mutations in the Ist2 tail phenocopy osh6Δ osh7Δ deletion: they decrease cellular PS levels and block PS transport to the PM. Our study unveils an unexpected partnership between a TMEM16-like protein and a soluble LTP, which together mediate lipid transport at contact sites.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
| | - Véronique Albanèse
- Université de Paris, CNRS, Institut Jacques Monod, F-75006, Paris, France
| | - Nicolas-Frédéric Lipp
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS and Université Côte d'Azur, 06560 Valbonne, France
| | - Lucile Fleuriot
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS and Université Côte d'Azur, 06560 Valbonne, France
| | - Delphine Debayle
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS and Université Côte d'Azur, 06560 Valbonne, France
| | - Guillaume Drin
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS and Université Côte d'Azur, 06560 Valbonne, France
| | - Alenka Čopič
- Université de Paris, CNRS, Institut Jacques Monod, F-75006, Paris, France
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121
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Walpole GFW, Grinstein S. Endocytosis and the internalization of pathogenic organisms: focus on phosphoinositides. F1000Res 2020; 9. [PMID: 32494357 PMCID: PMC7233180 DOI: 10.12688/f1000research.22393.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/07/2020] [Indexed: 12/18/2022] Open
Abstract
Despite their comparatively low abundance in biological membranes, phosphoinositides are key to the regulation of a diverse array of signaling pathways and direct membrane traffic. The role of phosphoinositides in the initiation and progression of endocytic pathways has been studied in considerable depth. Recent advances have revealed that distinct phosphoinositide species feature prominently in clathrin-dependent and -independent endocytosis as well as in phagocytosis and macropinocytosis. Moreover, a variety of intracellular and cell-associated pathogens have developed strategies to commandeer host cell phosphoinositide metabolism to gain entry and/or metabolic advantage, thereby promoting their survival and proliferation. Here, we briefly survey the current knowledge on the involvement of phosphoinositides in endocytosis, phagocytosis, and macropinocytosis and highlight several examples of molecular mimicry employed by pathogens to either “hitch a ride” on endocytic pathways endogenous to the host or create an entry path of their own.
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Affiliation(s)
- Glenn F W Walpole
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
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122
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Balla T, Kim YJ, Alvarez-Prats A, Pemberton J. Lipid Dynamics at Contact Sites Between the Endoplasmic Reticulum and Other Organelles. Annu Rev Cell Dev Biol 2020; 35:85-109. [PMID: 31590585 DOI: 10.1146/annurev-cellbio-100818-125251] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Phospholipids are synthesized primarily within the endoplasmic reticulum and are subsequently distributed to various subcellular membranes to maintain the unique lipid composition of specific organelles. As a result, in most cases, the steady-state localization of membrane phospholipids does not match their site of synthesis. This raises the question of how diverse lipid species reach their final membrane destinations and what molecular processes provide the energy to maintain the lipid gradients that exist between various membrane compartments. Recent studies have highlighted the role of inositol phospholipids in the nonvesicular transport of lipids at membrane contact sites. This review attempts to summarize our current understanding of these complex lipid dynamics and highlights their implications for defining future research directions.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA;
| | - Yeun Ju Kim
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA;
| | - Alejandro Alvarez-Prats
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA;
| | - Joshua Pemberton
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA;
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123
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Abstract
All lipid transport proteins in eukaryotes are thought to shuttle lipids between cellular membranes. In this issue, Li et al. (2020. J. Cell Biol.https://doi.org/10.1083/jcb.202001161) show that Vps13 has a channel-like domain that may allow lipids to flow between closely apposed membranes at contact sites.
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Affiliation(s)
- William A. Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - James H. Hurley
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA
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124
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Zhang B, Peng L, Zhu N, Yu Q, Li M. Novel role of the phosphatidylinositol phosphatase Sac1 in membrane homeostasis and polarized growth in Candida albicans. Int J Med Microbiol 2020; 310:151418. [PMID: 32245626 DOI: 10.1016/j.ijmm.2020.151418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 02/16/2020] [Accepted: 03/19/2020] [Indexed: 10/24/2022] Open
Abstract
Phosphoinositides (PIPs) are one kind of membrane components functioning in many intracellular processes, especially in signaling transduction and membrane transport. Phosphatidylinositide phosphatases (PIPases) are specifically important for the PIP homeostasis in cell. In our previous study, we have identified the actin-related protein CaSac1 in Candida albicans, while its functional mechanisms in regulating membrane homeostasis has not been identified. Here, we show that the PIPase CaSac1 is a main membrane-related protein and regulates hyphal polarization by governing phosphoinositide dynamic and plasma membrane (PM) electrostatic field. Deletion of CaSAC1 resulted in large-scale abnormal redistribution of phosphatidylinositide 4-phosphate (PI4P) from the endomembrane to the PM. This abnormality further led to disturbance of the PM's negative electrostatic field and abnormally spotted distribution of phosphatidylinositide 4,5-bisphosphate (PI(4,5)P2). These changes led to a severe defect in polarized hyphal growth, which could be diminished with recovery of the PM's negative electrostatic field by the anionic polymer polyacrylic acid (PAA). This study revealed that the PIPase CaSac1 plays an essential role in regulating membrane homeostasis and membrane traffic, contributing to establishment of polarized hyphal growth.
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Affiliation(s)
- Bing Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China; College of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
| | - Liping Peng
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Nali Zhu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Qilin Yu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China.
| | - Mingchun Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China.
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125
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Torres M, Rosselló CA, Fernández-García P, Lladó V, Kakhlon O, Escribá PV. The Implications for Cells of the Lipid Switches Driven by Protein-Membrane Interactions and the Development of Membrane Lipid Therapy. Int J Mol Sci 2020; 21:ijms21072322. [PMID: 32230887 PMCID: PMC7177374 DOI: 10.3390/ijms21072322] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 03/17/2020] [Accepted: 03/19/2020] [Indexed: 02/06/2023] Open
Abstract
The cell membrane contains a variety of receptors that interact with signaling molecules. However, agonist-receptor interactions not always activate a signaling cascade. Amphitropic membrane proteins are required for signal propagation upon ligand-induced receptor activation. These proteins localize to the plasma membrane or internal compartments; however, they are only activated by ligand-receptor complexes when both come into physical contact in membranes. These interactions enable signal propagation. Thus, signals may not propagate into the cell if peripheral proteins do not co-localize with receptors even in the presence of messengers. As the translocation of an amphitropic protein greatly depends on the membrane's lipid composition, regulation of the lipid bilayer emerges as a novel therapeutic strategy. Some of the signals controlled by proteins non-permanently bound to membranes produce dramatic changes in the cell's physiology. Indeed, changes in membrane lipids induce translocation of dozens of peripheral signaling proteins from or to the plasma membrane, which controls how cells behave. We called these changes "lipid switches", as they alter the cell's status (e.g., proliferation, differentiation, death, etc.) in response to the modulation of membrane lipids. Indeed, this discovery enables therapeutic interventions that modify the bilayer's lipids, an approach known as membrane-lipid therapy (MLT) or melitherapy.
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Affiliation(s)
- Manuel Torres
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, Ctra. de Valldemossa km 7.5, E-07122 Palma, Spain; (M.T.); (C.A.R.); (P.F.-G.); (V.L.)
- Department of R&D, Laminar Pharmaceuticals SL. ParcBit, Ed. Naorte B, E-07121 Palma, Spain
| | - Catalina Ana Rosselló
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, Ctra. de Valldemossa km 7.5, E-07122 Palma, Spain; (M.T.); (C.A.R.); (P.F.-G.); (V.L.)
- Department of R&D, Laminar Pharmaceuticals SL. ParcBit, Ed. Naorte B, E-07121 Palma, Spain
| | - Paula Fernández-García
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, Ctra. de Valldemossa km 7.5, E-07122 Palma, Spain; (M.T.); (C.A.R.); (P.F.-G.); (V.L.)
- Department of R&D, Laminar Pharmaceuticals SL. ParcBit, Ed. Naorte B, E-07121 Palma, Spain
| | - Victoria Lladó
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, Ctra. de Valldemossa km 7.5, E-07122 Palma, Spain; (M.T.); (C.A.R.); (P.F.-G.); (V.L.)
- Department of R&D, Laminar Pharmaceuticals SL. ParcBit, Ed. Naorte B, E-07121 Palma, Spain
| | - Or Kakhlon
- Department of Neurology, Hadassah-Hebrew University Medical Center, Ein Kerem, 91120 Jerusalem, Israel;
| | - Pablo Vicente Escribá
- Laboratory of Molecular Cell Biomedicine, Department of Biology, University of the Balearic Islands, Ctra. de Valldemossa km 7.5, E-07122 Palma, Spain; (M.T.); (C.A.R.); (P.F.-G.); (V.L.)
- Correspondence:
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126
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Nagashima S, Tábara LC, Tilokani L, Paupe V, Anand H, Pogson JH, Zunino R, McBride HM, Prudent J. Golgi-derived PI (4 )P-containing vesicles drive late steps of mitochondrial division. Science 2020; 367:1366-1371. [PMID: 32193326 DOI: 10.1126/science.aax6089] [Citation(s) in RCA: 168] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 12/09/2019] [Accepted: 02/27/2020] [Indexed: 12/31/2022]
Abstract
Mitochondrial plasticity is a key regulator of cell fate decisions. Mitochondrial division involves Dynamin-related protein-1 (Drp1) oligomerization, which constricts membranes at endoplasmic reticulum (ER) contact sites. The mechanisms driving the final steps of mitochondrial division are still unclear. Here, we found that microdomains of phosphatidylinositol 4-phosphate [PI(4)P] on trans-Golgi network (TGN) vesicles were recruited to mitochondria-ER contact sites and could drive mitochondrial division downstream of Drp1. The loss of the small guanosine triphosphatase ADP-ribosylation factor 1 (Arf1) or its effector, phosphatidylinositol 4-kinase IIIβ [PI(4)KIIIβ], in different mammalian cell lines prevented PI(4)P generation and led to a hyperfused and branched mitochondrial network marked with extended mitochondrial constriction sites. Thus, recruitment of TGN-PI(4)P-containing vesicles at mitochondria-ER contact sites may trigger final events leading to mitochondrial scission.
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Affiliation(s)
- Shun Nagashima
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Luis-Carlos Tábara
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Lisa Tilokani
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Vincent Paupe
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Hanish Anand
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Joe H Pogson
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3B 2B4, Canada
| | - Rodolfo Zunino
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3B 2B4, Canada
| | - Heidi M McBride
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3B 2B4, Canada.
| | - Julien Prudent
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK.
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127
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Omnus DJ, Cadou A, Thomas FB, Bader JM, Soh N, Chung GHC, Vaughan AN, Stefan CJ. A heat-sensitive Osh protein controls PI4P polarity. BMC Biol 2020; 18:28. [PMID: 32169085 PMCID: PMC7071650 DOI: 10.1186/s12915-020-0758-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 02/26/2020] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Phosphoinositide lipids provide spatial landmarks during polarized cell growth and migration. Yet how phosphoinositide gradients are oriented in response to extracellular cues and environmental conditions is not well understood. Here, we elucidate an unexpected mode of phosphatidylinositol 4-phosphate (PI4P) regulation in the control of polarized secretion. RESULTS We show that PI4P is highly enriched at the plasma membrane of growing daughter cells in budding yeast where polarized secretion occurs. However, upon heat stress conditions that redirect secretory traffic, PI4P rapidly increases at the plasma membrane in mother cells resulting in a more uniform PI4P distribution. Precise control of PI4P distribution is mediated through the Osh (oxysterol-binding protein homology) proteins that bind and present PI4P to a phosphoinositide phosphatase. Interestingly, Osh3 undergoes a phase transition upon heat stress conditions, resulting in intracellular aggregates and reduced cortical localization. Both the Osh3 GOLD and ORD domains are sufficient to form heat stress-induced aggregates, indicating that Osh3 is highly tuned to heat stress conditions. Upon loss of Osh3 function, the polarized distribution of both PI4P and the exocyst component Exo70 are impaired. Thus, an intrinsically heat stress-sensitive PI4P regulatory protein controls the spatial distribution of phosphoinositide lipid metabolism to direct secretory trafficking as needed. CONCLUSIONS Our results suggest that control of PI4P metabolism by Osh proteins is a key determinant in the control of polarized growth and secretion.
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Affiliation(s)
- Deike J Omnus
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom
- Present address: Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Angela Cadou
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Ffion B Thomas
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Jakob M Bader
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom
- Present address: Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Nathaniel Soh
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Gary H C Chung
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Andrew N Vaughan
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Christopher J Stefan
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, United Kingdom.
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128
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Bigay J, Mesmin B, Antonny B. [A lipid exchange market : vectorial cholesterol transport by the protein OSBP]. Med Sci (Paris) 2020; 36:130-136. [PMID: 32129748 DOI: 10.1051/medsci/2020009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cholesterol is synthesized in the endoplasmic reticulum (RE) and then transported to cellular compartments whose functions require high cholesterol levels. Here, we describe the mechanism by which cholesterol is transported from the RE to the trans-Golgi network (TGN) by the protein OSBP (Oxysterol-Binding Protein). OSBP has two complementary activities. First, it tethers the RE to the TGN by forming a contact site where the two membranes are about twenty nanometers away. Then, it exchanges RE cholesterol for a TGN lipid, phosphatidylinositol 4-phosphate (PI4P). Eventually, PI4P is hydrolyzed at the RE, making the exchange cycle irreversible. Thus, OSBP is at the center of a lipid exchange market where a transported cholesterol "costs" a PI4P. Antiviral or anti-cancer molecules target OSBP, suggesting the importance of the OSBP cycle in different physiopathological contexts. The general principles of this cycle are shared by other lipid-transfer proteins.
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Affiliation(s)
- Joëlle Bigay
- Institut de Pharmacologie Moléculaire et Cellulaire, Université Côte d'Azur et CNRS, UMR 7275, 660 route des lucioles, 06560 Valbonne, France
| | - Bruno Mesmin
- Institut de Pharmacologie Moléculaire et Cellulaire, Université Côte d'Azur et CNRS, UMR 7275, 660 route des lucioles, 06560 Valbonne, France
| | - Bruno Antonny
- Institut de Pharmacologie Moléculaire et Cellulaire, Université Côte d'Azur et CNRS, UMR 7275, 660 route des lucioles, 06560 Valbonne, France
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129
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How is the acyl chain composition of phosphoinositides created and does it matter? Biochem Soc Trans 2020; 47:1291-1305. [PMID: 31657437 PMCID: PMC6824679 DOI: 10.1042/bst20190205] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/27/2019] [Accepted: 10/01/2019] [Indexed: 12/11/2022]
Abstract
The phosphoinositide (PIPn) family of signalling phospholipids are central regulators in membrane cell biology. Their varied functions are based on the phosphorylation pattern of their inositol ring, which can be recognized by selective binding domains in their effector proteins and be modified by a series of specific PIPn kinases and phosphatases, which control their interconversion in a spatial and temporal manner. Yet, a unique feature of PIPns remains largely unexplored: their unusually uniform acyl chain composition. Indeed, while most phospholipids present a range of molecular species comprising acyl chains of diverse length and saturation, PIPns in several organisms and tissues show the predominance of a single hydrophobic backbone, which in mammals is composed of arachidonoyl and stearoyl chains. Despite evolution having favoured this specific PIPn configuration, little is known regarding the mechanisms and functions behind it. In this review, we explore the metabolic pathways that could control the acyl chain composition of PIPns as well as the potential roles of this selective enrichment. While our understanding of this phenomenon has been constrained largely by the technical limitations in the methods traditionally employed in the PIPn field, we believe that the latest developments in PIPn analysis should shed light onto this old question.
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130
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Endoplasmic reticulum-plasma membrane contacts: Principals of phosphoinositide and calcium signaling. Curr Opin Cell Biol 2020; 63:125-134. [PMID: 32088611 DOI: 10.1016/j.ceb.2020.01.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 01/18/2020] [Accepted: 01/20/2020] [Indexed: 12/29/2022]
Abstract
The endoplasmic reticulum (ER) forms an extensive network of membrane contact sites with intra-cellular organelles and the plasma membrane (PM). Interorganelle contacts have vital roles in membrane lipid and ion dynamics. In particular, ER-PM contacts are integral to numerous inter-cellular and intra-cellular signaling pathways including phosphoinositide lipid and calcium signaling, mechanotransduction, metabolic regulation, and cell stress responses. Accordingly, ER-PM contacts serve important signaling functions in excitable cells including neurons and muscle and endocrine cells. This review highlights recent advances in our understanding of the vital roles for ER-PM contacts in phosphoinositide and calcium signaling and how signaling pathways in turn regulate proteins that form and function at ER-PM contacts.
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131
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ER-Golgi membrane contact sites. Biochem Soc Trans 2020; 48:187-197. [DOI: 10.1042/bst20190537] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 01/20/2020] [Accepted: 01/24/2020] [Indexed: 12/13/2022]
Abstract
Membrane contact sites (MCSs) are sites where the membranes of two different organelles come into close apposition (10–30 nm). Different classes of proteins populate MCSs including factors that act as tethers between the two membranes, proteins that use the MCSs for their function (mainly lipid or ion exchange), and regulatory proteins and enzymes that can act in trans across the MCSs. The ER-Golgi MCSs were visualized by electron microscopists early in the sixties but have remained elusive for decades due to a lack of suitable methodological approaches. Here we report recent progress in the study of this class of MCSs that has led to the identification of their main morphological features and of some of their components and roles. Among these, lipid transfer proteins and lipid exchange have been the most studied and understood so far. However, many unknowns remain regarding their regulation and their role in controlling key TGN functions such as sorting and trafficking as well as their relevance in physiological and pathological conditions.
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132
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Zhao K, Foster J, Ridgway ND. Oxysterol-binding protein-related protein 1 variants have opposing cholesterol transport activities from the endolysosomes. Mol Biol Cell 2020; 31:793-802. [PMID: 32023146 PMCID: PMC7185962 DOI: 10.1091/mbc.e19-12-0697] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
OSBPL1 encodes the full-length oxysterol-binding protein-related protein ORP1L, which transports LDL-derived cholesterol at membrane contacts between the late endosomes/lysosomes (LEL) and the endoplasmic reticulum (ER). OSBPL1 also encodes the truncated variant ORP1S that contains only the C-terminal lipid binding domain. HeLa cells in which both variants were knocked out (ORP1-null) were used to determine the functional relationship between ORP1L and ORP1S with respect to cellular cholesterol localization and regulation. ORP1-null cells accumulated cholesterol in LEL and had reduced plasma membrane (PM) cholesterol. PM cholesterol was restored by expression of wild-type ORP1S or a phosphatidylinositol phosphate-binding mutant but not by a sterol-binding mutant. Expression of ORP2, another truncated variant, also restored PM cholesterol in ORP1-null cells. Consistent with a LEL-to-PM cholesterol transport activity, a small fraction of ORP1S was detected on the PM. As a consequence of reduced delivery of cholesterol to the PM in ORP1-null cells, cholesterol was diverted to the ER resulting in normalization of de novo cholesterol synthesis. The deficiency in PM cholesterol also reduced ABCA1-dependent cholesterol efflux and LDL receptor activity in ORP1-null cells. We conclude that ORP1S, which lacks discrete membrane-targeting motifs, transports cholesterol from LEL to the PM.
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Affiliation(s)
- Kexin Zhao
- Departments of Pediatrics and Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Jason Foster
- Departments of Pediatrics and Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Neale D Ridgway
- Departments of Pediatrics and Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
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133
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Colin LA, Jaillais Y. Phospholipids across scales: lipid patterns and plant development. CURRENT OPINION IN PLANT BIOLOGY 2020; 53:1-9. [PMID: 31580918 DOI: 10.1016/j.pbi.2019.08.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 08/09/2019] [Accepted: 08/14/2019] [Indexed: 05/18/2023]
Abstract
Phospholipids are major building blocks of cell membranes and as such they have a key structural role in maintaining their integrity as a hydrophobic barrier. However, phospholipids not only have structural but also regulatory functions that are involved in a myriad of signaling pathways. Integrative approaches in plants recently revealed that certain phospholipids have distinct patterns of accumulation at the tissue or organ scales, which turned out to be important cues in a developmental context. Using examples on different phospholipid classes, including phosphatidylinositol-4,5-bisphosphate, phosphatidylserine, phosphatidylcholine, and phosphatidic acid, we review how spatio-temporal lipid patterns arise at the organismal level and what are their downstream consequences on plant development.
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Affiliation(s)
- Leia Axelle Colin
- Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342 Lyon, France
| | - Yvon Jaillais
- Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342 Lyon, France.
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134
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Chauhan N, Sere YY, Sokol AM, Graumann J, Menon AK. A PhotoClick cholesterol‐based quantitative proteomics screen for cytoplasmic sterol‐binding proteins in
Saccharomyces cerevisiae. Yeast 2020; 37:15-25. [DOI: 10.1002/yea.3448] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/30/2019] [Accepted: 11/15/2019] [Indexed: 02/02/2023] Open
Affiliation(s)
- Neha Chauhan
- Department of Biochemistry Weill Cornell Medical College 1300 York Ave. New York NY 10065 USA
| | - Yves Y. Sere
- Department of Biochemistry Weill Cornell Medical College 1300 York Ave. New York NY 10065 USA
| | - Anna M. Sokol
- Biomolecular Mass Spectrometry Max Planck Institute for Heart and Lung Research, W.G. Kerckhoff Institute Ludwigstr. 43 Bad Nauheim Germany
- Biomolecular Mass Spectrometry German Centre for Cardiovascular Research (DZHK), Rhine‐Main site Bad Nauheim Germany
| | - Johannes Graumann
- Biomolecular Mass Spectrometry Max Planck Institute for Heart and Lung Research, W.G. Kerckhoff Institute Ludwigstr. 43 Bad Nauheim Germany
- Biomolecular Mass Spectrometry German Centre for Cardiovascular Research (DZHK), Rhine‐Main site Bad Nauheim Germany
| | - Anant K. Menon
- Department of Biochemistry Weill Cornell Medical College 1300 York Ave. New York NY 10065 USA
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135
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Shin JJH, Liu P, Chan LJ, Ullah A, Pan J, Borchers CH, Burke JE, Stefan C, Smits GJ, Loewen CJR. pH Biosensing by PI4P Regulates Cargo Sorting at the TGN. Dev Cell 2020; 52:461-476.e4. [PMID: 31928972 DOI: 10.1016/j.devcel.2019.12.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/04/2019] [Accepted: 12/13/2019] [Indexed: 01/09/2023]
Abstract
Phosphoinositides, diacylglycerolpyrophosphate, ceramide-1-phosphate, and phosphatidic acid belong to a unique class of membrane signaling lipids that contain phosphomonoesters in their headgroups having pKa values in the physiological range. The phosphomonoester headgroup of phosphatidic acid enables this lipid to act as a pH biosensor as changes in its protonation state with intracellular pH regulate binding to effector proteins. Here, we demonstrate that binding of pleckstrin homology (PH) domains to phosphatidylinositol 4-phosphate (PI4P) in the yeast trans-Golgi network (TGN) is dependent on intracellular pH, indicating PI4P is a pH biosensor. pH biosensing by TGN PI4P in response to nutrient availability governs protein sorting at the TGN, likely by regulating sterol transfer to the TGN by Osh1, a member of the conserved oxysterol-binding protein (OSBP) family of lipid transfer proteins. Thus, pH biosensing by TGN PI4P allows for direct metabolic regulation of protein trafficking and cell growth.
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Affiliation(s)
- John J H Shin
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; MRC Laboratory for Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Peter Liu
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Leslie J Chan
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Azmat Ullah
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1018 XH Amsterdam, The Netherlands
| | - Jingxi Pan
- University of Victoria, Genome British Columbia Proteomics Centre, Vancouver Island Technology Park, #3101-4464 Markham St., Victoria, BC V8Z 7X8, Canada; Department of Biochemistry & Microbiology, University of Victoria, 3800 Finnerty Rd., Victoria, BC V8P 5C2, Canada
| | - Christoph H Borchers
- University of Victoria, Genome British Columbia Proteomics Centre, Vancouver Island Technology Park, #3101-4464 Markham St., Victoria, BC V8Z 7X8, Canada; Department of Biochemistry & Microbiology, University of Victoria, 3800 Finnerty Rd., Victoria, BC V8P 5C2, Canada
| | - John E Burke
- Department of Biochemistry & Microbiology, University of Victoria, 3800 Finnerty Rd., Victoria, BC V8P 5C2, Canada
| | - Christopher Stefan
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Gertien J Smits
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1018 XH Amsterdam, The Netherlands
| | - Christopher J R Loewen
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
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136
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The Role of Membrane Surface Charge in Phagocytosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1246:43-54. [DOI: 10.1007/978-3-030-40406-2_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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137
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Prinz WA, Toulmay A, Balla T. The functional universe of membrane contact sites. Nat Rev Mol Cell Biol 2020; 21:7-24. [PMID: 31732717 PMCID: PMC10619483 DOI: 10.1038/s41580-019-0180-9] [Citation(s) in RCA: 425] [Impact Index Per Article: 85.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2019] [Indexed: 12/13/2022]
Abstract
Organelles compartmentalize eukaryotic cells, enhancing their ability to respond to environmental and developmental changes. One way in which organelles communicate and integrate their activities is by forming close contacts, often called 'membrane contact sites' (MCSs). Interest in MCSs has grown dramatically in the past decade as it is has become clear that they are ubiquitous and have a much broader range of critical roles in cells than was initially thought. Indeed, functions for MCSs in intracellular signalling (particularly calcium signalling, reactive oxygen species signalling and lipid signalling), autophagy, lipid metabolism, membrane dynamics, cellular stress responses and organelle trafficking and biogenesis have now been reported.
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Affiliation(s)
- William A Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
| | - Alexandre Toulmay
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Tamas Balla
- National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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138
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Pemberton JG, Kim YJ, Balla T. Integrated regulation of the phosphatidylinositol cycle and phosphoinositide-driven lipid transport at ER-PM contact sites. Traffic 2019; 21:200-219. [PMID: 31650663 DOI: 10.1111/tra.12709] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/02/2019] [Accepted: 10/16/2019] [Indexed: 12/20/2022]
Abstract
Among the structural phospholipids that form the bulk of eukaryotic cell membranes, phosphatidylinositol (PtdIns) is unique in that it also serves as the common precursor for low-abundance regulatory lipids, collectively referred to as polyphosphoinositides (PPIn). The metabolic turnover of PPIn species has received immense attention because of the essential functions of these lipids as universal regulators of membrane biology and their dysregulation in numerous human pathologies. The diverse functions of PPIn lipids occur, in part, by orchestrating the spatial organization and conformational dynamics of peripheral or integral membrane proteins within defined subcellular compartments. The emerging role of stable contact sites between adjacent membranes as specialized platforms for the coordinate control of ion exchange, cytoskeletal dynamics, and lipid transport has also revealed important new roles for PPIn species. In this review, we highlight the importance of membrane contact sites formed between the endoplasmic reticulum (ER) and plasma membrane (PM) for the integrated regulation of PPIn metabolism within the PM. Special emphasis will be placed on non-vesicular lipid transport during control of the PtdIns biosynthetic cycle as well as toward balancing the turnover of the signaling PPIn species that define PM identity.
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Affiliation(s)
- Joshua G Pemberton
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, Maryland
| | - Yeun Ju Kim
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, Maryland
| | - Tamas Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, Maryland
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139
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Yang X, Liang J, Ding L, Li X, Lam SM, Shui G, Ding M, Huang X. Phosphatidylserine synthase regulates cellular homeostasis through distinct metabolic mechanisms. PLoS Genet 2019; 15:e1008548. [PMID: 31869331 PMCID: PMC6946173 DOI: 10.1371/journal.pgen.1008548] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 01/07/2020] [Accepted: 12/02/2019] [Indexed: 12/18/2022] Open
Abstract
Phosphatidylserine (PS), synthesized in the endoplasmic reticulum (ER) by phosphatidylserine synthase (PSS), is transported to the plasma membrane (PM) and mitochondria through distinct routes. The in vivo functions of PS at different subcellular locations and the coordination between different PS transport routes are not fully understood. Here, we report that Drosophila PSS regulates cell growth, lipid storage and mitochondrial function. In pss RNAi, reduced PS depletes plasma membrane Akt, contributing to cell growth defects; the metabolic shift from phospholipid synthesis to neutral lipid synthesis results in ectopic lipid accumulation; and the reduction of mitochondrial PS impairs mitochondrial protein import and mitochondrial integrity. Importantly, reducing PS transport from the ER to PM by loss of PI4KIIIα partially rescues the mitochondrial defects of pss RNAi. Together, our results uncover a balance between different PS transport routes and reveal that PSS regulates cellular homeostasis through distinct metabolic mechanisms. Phosphatidylserine (PS), a membrane phospholipid synthesized in the endoplasmic reticulum (ER) by the enzyme phosphatidylserine synthase (PSS), is transported to the plasma membrane (PM) and mitochondria through different paths. The cellular functions of PS at different places in the cell and the mechanisms that coordinate the different PS transport paths are not fully understood. Here, we identified that PSS regulates cell growth, lipid storage and mitochondrial function in the fruit fly larval salivary gland. We showed that loss of pss function has three effects: (1) reduced levels of PS lead to reduced levels of plasma membrane Akt, a key component in the insulin pathway, which is important for cell growth; (2) it causes a shift from phospholipid synthesis to neutral lipid synthesis, which results in excess lipid accumulation; and (3) it reduces the level of mitochondrial PS, which impairs mitochondrial protein import and mitochondrial morphology. We also found that reducing the transport of PS from the ER to PM partially rescues the mitochondrial defects caused by loss of pss function. Together, our results reveal that PSS regulates cellular homeostasis through distinct metabolic changes, and uncover a balance between different PS transport pathways.
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Affiliation(s)
- Xiao Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- School of Life Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, TaiAn, China
| | - Jingjing Liang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Long Ding
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xia Li
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Sin-Man Lam
- LipidAll Technologies Co., Ltd. Changzhou, China
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Mei Ding
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- * E-mail:
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140
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Abstract
Lipids are distributed in a highly heterogeneous fashion in different cellular membranes. Only a minority of lipids achieve their final intracellular distribution through transport by vesicles. Instead, the bulk of lipid traffic is mediated by a large group of lipid transfer proteins (LTPs), which move small numbers of lipids at a time using hydrophobic cavities that stabilize lipid molecules outside membranes. Although the first LTPs were discovered almost 50 years ago, most progress in understanding these proteins has been made in the past few years, leading to considerable temporal and spatial refinement of our understanding of the function of these lipid transporters. The number of known LTPs has increased, with exciting discoveries of their multimeric assembly. Structural studies of LTPs have progressed from static crystal structures to dynamic structural approaches that show how conformational changes contribute to lipid handling at a sub-millisecond timescale. A major development has been the finding that many intracellular LTPs localize to two organelles at the same time, forming a shuttle, bridge or tube that links donor and acceptor compartments. The understanding of how different lipids achieve their final destination at the molecular level allows a better explanation of the range of defects that occur in diseases associated with lipid transport and distribution, opening up the possibility of developing therapies that specifically target lipid transfer.
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141
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Moosavi B, Gao M, Zhu XL, Yang GF. The anti-cancer compound Schweinfurthin A targets Osh2 and disrupts lipid metabolism in the yeast model. Bioorg Chem 2019; 94:103471. [PMID: 31813476 DOI: 10.1016/j.bioorg.2019.103471] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 11/09/2019] [Accepted: 11/23/2019] [Indexed: 12/17/2022]
Abstract
Schweinfurthin A (Sch A) is a natural product with a selective and strong anti-cancer effect. Although it is known to target oxysterol binding proteins, the detailed mode of action is not well understood. Here, we provide strong evidence that yeast cells can be used as a eukaryotic model system to decipher the molecular modes of Sch A. We show that Sch A (100 µM) targets Osh2 (a yeast oxysterol binding protein homolog) genetically and taking advantage of computational chemistry indicate that the tetrahydro-2H-xanthene portion of Sch A forms H-bonds with residues Ser105, Val113, and Lys201, while its isoprenoid side chain is placed in a hydrophobic pocket lined by the side chains of Leu41, Leu45, Leu58, Met56, and Phe174 in Osh2. This model suggests that Sch A occupies the same binding pocket in Osh2 which is occupied by its natural substrate, ergosterol. Osh proteins transport sterol and PI(4)P in a cyclic manner between two membranes. Therefore, we suggest that Sch A interferes with this function of Osh2. In support of this hypothesis, we show that Sch A toxicity rate changes upon manipulating the enzymes that modify the levels of sterol and PI(4)P. This approach also informs how Sch A exerts its toxic effect in yeast cells. These enzymes include Coq1, Sac1, Plc1, Stt4, Pik1, and Mss4. We demonstrate that Coq1 an enzyme required for coenzyme Q synthesis (also involved in sterol metabolism indirectly), Sac1, and Stt4 the enzymes governing PI(4)P level modify Sch A toxicity and finally propose Sch A disrupts sterol/PI(4)P exchange between membranes by occupying the sterol/PI(4)P binding pocket in Osh2.
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Affiliation(s)
- Behrooz Moosavi
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, PR China.
| | - Mengqi Gao
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, PR China
| | - Xiao-Lei Zhu
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, PR China
| | - Guang-Fu Yang
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, PR China.
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142
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Hanada K. Organelle contacts: Sub-organelle zones to facilitate rapid and accurate inter-organelle trafficking of lipids. Traffic 2019; 21:189-196. [PMID: 31705775 DOI: 10.1111/tra.12716] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 11/01/2019] [Accepted: 11/05/2019] [Indexed: 12/27/2022]
Abstract
When one person wants to communicate securely with another, he/she should contact the other person directly. This rule applies not only to human society, but also to the intracellular micro-society. In the past two decades, it has become increasingly clear that the sub-organelle regions called membrane contact sites (MCSs) are pivotal for inter-organelle transport of lipids in cells, as highlighted in the thematic review series "Interorganelle trafficking of lipids" held in Traffic in 2014-2015. In this commentary, we will describe how the currently prevailing model for lipid trafficking at MCSs was generated, and comment on three important issues that have not been explored: (a1) the principles guiding the generation of an asymmetrical inter-organelle flow of lipids in cells, (b2) the advantages in lipid trafficking at organelle contacts, and (c3) the dynamic network of inter-organelle lipid trafficking.
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Affiliation(s)
- Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
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143
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Levin‐Konigsberg R, Grinstein S. Phagosome‐endoplasmic reticulum contacts: Kissing and not running. Traffic 2019; 21:172-180. [DOI: 10.1111/tra.12708] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/14/2019] [Accepted: 10/16/2019] [Indexed: 12/20/2022]
Affiliation(s)
| | - Sergio Grinstein
- Division of Cell BiologyHospital for Sick Children Toronto Ontario Canada
- Department of BiochemistryUniversity of Toronto Toronto Ontario Canada
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144
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Vanni S, Riccardi L, Palermo G, De Vivo M. Structure and Dynamics of the Acyl Chains in the Membrane Trafficking and Enzymatic Processing of Lipids. Acc Chem Res 2019; 52:3087-3096. [PMID: 31364837 DOI: 10.1021/acs.accounts.9b00134] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The regulatory chemical mechanisms of lipid trafficking and degradation are involved in many pathophysiological processes, being implicated in severe pain, inflammation, and cancer. In addition, the processing of lipids is also relevant for industrial and environmental applications. However, there is poor understanding of the chemical features that control lipid membrane trafficking and allow lipid-degrading enzymes to efficiently select and hydrolyze specific fatty acids from a complex cellular milieu of bioactive lipids. This is particularly true for lipid acyl chains, which have diverse structures that can critically affect the many complex reactions needed to elongate, desaturate, or transport fatty acids. Building upon our own contributions in this field, we will discuss how molecular simulations, integrated with experimental evidence, have revealed that the structure and dynamics of the lipid tail are actively involved in modulating membrane trafficking at cellular organelles, and enzymatic reactions at cell membranes. Further evidence comes from recent crystal structures of lipid receptors and remodeling enzymes. Taken together, these recent works have identified those structural features of the lipid acyl chain that are crucial for the regioselectivity and stereospecificity of essential desaturation reactions. In this context, we will first illustrate how atomistic and coarse-grained simulations have elucidated the structure-function relationships between the chemical composition of the lipid's acyl chains and the molecular properties of lipid bilayers. Particular emphasis will be given to the prominent chemical role of the number of double carbon-carbon bonds along the lipid acyl chain, that is, discriminating between saturated, monounsaturated, and polyunsaturated lipids. Different levels of saturation in fatty acid molecules dramatically influence the biophysical properties of lipid assemblies and their interaction with proteins. We will then discuss the processing of lipids by membrane-bound enzymes. Our focus will be on lipids such as anandamide and 2-arachidonoylglycerol. These are the main molecules that act as neurotransmitters in the endocannabinoid system. Specifically, recent findings indicate a crucial interplay between the level of saturation of the lipid tail, its energetically and sterically favored conformations, and the hydrophobic accessory cavities in lipid-degrading enzymes, which help form catalytically active conformations of the selected substrate. This Account will emphasize how the specific chemical structure of acyl chains affects the molecular mechanisms for modulating membrane trafficking and selective hydrolysis. The results examined here show that, by using molecular simulations to investigate lipid plasticity and substrate flexibility, researchers can enrich their interpretation of experimental results about the structure-function relationships of lipids. This could positively impact chemical and biological studies in the field and ultimately support protein engineering studies and structure-based drug discovery to target lipid-processing enzymes.
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Affiliation(s)
- Stefano Vanni
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
- Université Côte d’Azur, CNRS, IPMC, 06560 Valbonne, France
| | - Laura Riccardi
- Laboratory of Molecular Modeling and Drug Discovery, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
| | - Giulia Palermo
- Department of Bioengineering, University of California Riverside, Riverside, California 92521, United States
| | - Marco De Vivo
- Laboratory of Molecular Modeling and Drug Discovery, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy
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145
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Masone MC, Morra V, Venditti R. Illuminating the membrane contact sites between the endoplasmic reticulum and the trans-Golgi network. FEBS Lett 2019; 593:3135-3148. [PMID: 31610025 DOI: 10.1002/1873-3468.13639] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/08/2019] [Accepted: 10/08/2019] [Indexed: 12/22/2022]
Abstract
Membrane contact sites (MCSs) between different organelles have been identified and extensively studied over the last decade. Several classes of MCSs have now well-established roles, although the contacts between the endoplasmic reticulum (ER) and the trans-side of the Golgi network (TGN) have long remained elusive. Until recently, the study of ER-TGN contact sites has represented a major challenge in the field, as a result of the lack of suitable visualization and isolation techniques. Only in the last 5 years has the combination of advanced technologies and innovative approaches permitted the identification of new molecular players and the functions of ER-TGN MCSs that couple lipid metabolism and anterograde transport. Although much has yet to be discovered, it is now established that ER-TGN MCSs control phosphatidyl-4-phosphate homeostasis by coupling the cis and the trans activity of the ER-resident 4-phosphatase Sac1. In this review, we focus on recent advances on the composition and function of ER-TGN MCSs.
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Affiliation(s)
| | - Valentina Morra
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Rossella Venditti
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy.,Department of Molecular Medicine and Medical Biotechnology, Medical School, University of Napoli Federico II, Naples, Italy
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146
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Kay JG, Fairn GD. Distribution, dynamics and functional roles of phosphatidylserine within the cell. Cell Commun Signal 2019; 17:126. [PMID: 31615534 PMCID: PMC6792266 DOI: 10.1186/s12964-019-0438-z] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 09/10/2019] [Indexed: 12/19/2022] Open
Abstract
Phosphatidylserine (PtdSer), an essential constituent of eukaryotic membranes, is the most abundant anionic phospholipid in the eukaryotic cell accounting for up to 10% of the total cellular lipid. Much of what is known about PtdSer is the role exofacial PtdSer plays in apoptosis and blood clotting. However, PtdSer is generally not externally exposed in healthy cells and plays a vital role in several intracellular signaling pathways, though relatively little is known about the precise subcellular localization, transmembrane topology and intracellular dynamics of PtdSer within the cell. The recent development of new, genetically-encoded probes able to detect phosphatidylserine is leading to a more in-depth understanding of the biology of this phospholipid. This review aims to give an overview of recent developments in our understanding of the role of PtdSer in intracellular signaling events derived from the use of these recently developed methods of phosphatidylserine detection.
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Affiliation(s)
- Jason G Kay
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, NY, 14214, USA.
| | - Gregory D Fairn
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, M5B 1W8, Canada. .,Department of Surgery, University of Toronto, Toronto, ON, M5S 1A8, Canada. .,Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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147
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Kattan WE, Chen W, Ma X, Lan TH, van der Hoeven D, van der Hoeven R, Hancock JF. Targeting plasma membrane phosphatidylserine content to inhibit oncogenic KRAS function. Life Sci Alliance 2019; 2:e201900431. [PMID: 31451509 PMCID: PMC6709719 DOI: 10.26508/lsa.201900431] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/16/2019] [Accepted: 08/19/2019] [Indexed: 12/14/2022] Open
Abstract
The small GTPase KRAS, which is frequently mutated in human cancers, must be localized to the plasma membrane (PM) for biological activity. We recently showed that the KRAS C-terminal membrane anchor exhibits exquisite lipid-binding specificity for select species of phosphatidylserine (PtdSer). We, therefore, investigated whether reducing PM PtdSer content is sufficient to abrogate KRAS oncogenesis. Oxysterol-related binding proteins ORP5 and ORP8 exchange PtdSer synthesized in the ER for phosphatidyl-4-phosphate synthesized in the PM. We show that depletion of ORP5 or ORP8 reduced PM PtdSer levels, resulting in extensive mislocalization of KRAS from the PM. Concordantly, ORP5 or ORP8 depletion significantly reduced proliferation and anchorage-independent growth of multiple KRAS-dependent cancer cell lines, and attenuated KRAS signaling in vivo. Similarly, functionally inhibiting ORP5 and ORP8 by inhibiting PI4KIIIα-mediated synthesis of phosphatidyl-4-phosphate at the PM selectively inhibited the growth of KRAS-dependent cancer cell lines over normal cells. Inhibiting KRAS function through regulating PM lipid PtdSer content may represent a viable strategy for KRAS-driven cancers.
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Affiliation(s)
- Walaa E Kattan
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Wei Chen
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Xiaoping Ma
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Tien Hung Lan
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
| | - Dharini van der Hoeven
- Department of Diagnostic and Biomedical Sciences, School of Dentistry, University of Texas Health Science Center, Houston, TX, USA
| | - Ransome van der Hoeven
- Department of Diagnostic and Biomedical Sciences, School of Dentistry, University of Texas Health Science Center, Houston, TX, USA
| | - John F Hancock
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
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148
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Levin-Konigsberg R, Montaño-Rendón F, Keren-Kaplan T, Li R, Ego B, Mylvaganam S, DiCiccio JE, Trimble WS, Bassik MC, Bonifacino JS, Fairn GD, Grinstein S. Phagolysosome resolution requires contacts with the endoplasmic reticulum and phosphatidylinositol-4-phosphate signalling. Nat Cell Biol 2019; 21:1234-1247. [PMID: 31570833 DOI: 10.1038/s41556-019-0394-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 08/19/2019] [Indexed: 01/01/2023]
Abstract
Phosphoinositides have a pivotal role in the maturation of nascent phagosomes into microbicidal phagolysosomes. Following degradation of their contents, mature phagolysosomes undergo resolution, a process that remains largely uninvestigated. Here we studied the role of phosphoinositides in phagolysosome resolution. Phosphatidylinositol-4-phosphate (PtdIns(4)P), which is abundant in maturing phagolysosomes, was depleted as they tubulated and resorbed. Depletion was caused, in part, by transfer of phagolysosomal PtdIns(4)P to the endoplasmic reticulum, a process mediated by oxysterol-binding protein-related protein 1L (ORP1L), a RAB7 effector. ORP1L formed discrete tethers between the phagolysosome and the endoplasmic reticulum, resulting in distinct regions with alternating PtdIns(4)P depletion and enrichment. Tubules emerged from PtdIns(4)P-rich regions, where ADP-ribosylation factor-like protein 8B (ARL8B) and SifA- and kinesin-interacting protein/pleckstrin homology domain-containing family M member 2 (SKIP/PLEKHM2) accumulated. SKIP binds preferentially to monophosphorylated phosphoinositides, of which PtdIns(4)P is most abundant in phagolysosomes, contributing to their tubulation. Accordingly, premature hydrolysis of PtdIns(4)P impaired SKIP recruitment and phagosome resolution. Thus, resolution involves phosphoinositides and tethering of phagolysosomes to the endoplasmic reticulum.
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Affiliation(s)
- Roni Levin-Konigsberg
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.,Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Fernando Montaño-Rendón
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Tal Keren-Kaplan
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Ren Li
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Braeden Ego
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Sivakami Mylvaganam
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Jessica E DiCiccio
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - William S Trimble
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Michael C Bassik
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Juan S Bonifacino
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Gregory D Fairn
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada. .,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.
| | - Sergio Grinstein
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada. .,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada. .,Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada. .,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.
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149
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An electrostatic switching mechanism to control the lipid transfer activity of Osh6p. Nat Commun 2019; 10:3926. [PMID: 31477717 PMCID: PMC6718676 DOI: 10.1038/s41467-019-11780-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 08/01/2019] [Indexed: 02/01/2023] Open
Abstract
A central assumption is that lipid transfer proteins (LTPs) bind transiently to organelle membranes to distribute lipids in the eukaryotic cell. Osh6p and Osh7p are yeast LTPs that transfer phosphatidylserine (PS) from the endoplasmic reticulum (ER) to the plasma membrane (PM) via PS/phosphatidylinositol-4-phosphate (PI4P) exchange cycles. It is unknown how, at each cycle, they escape from the electrostatic attraction of the PM, highly anionic, to return to the ER. Using cellular and in vitro approaches, we show that Osh6p reduces its avidity for anionic membranes once it captures PS or PI4P, due to a molecular lid closing its lipid-binding pocket. Thus, Osh6p maintains its transport activity between ER- and PM-like membranes. Further investigations reveal that the lid governs the membrane docking and activity of Osh6p because it is anionic. Our study unveils how an LTP self-limits its residency time on membranes, via an electrostatic switching mechanism, to transfer lipids efficiently. Osh6p and Osh7p are yeast lipid transfer proteins (LTPs) that must transiently interact with membranes but how they escape from the electrostatic attraction of the plasma membrane is unclear. Here authors show that Osh6p reduces its avidity for anionic membranes once it captures PS or PI4P, due to a molecular lid closing its lipid-binding pocket.
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150
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Olkkonen VM, Koponen A, Arora A. OSBP-related protein 2 (ORP2): Unraveling its functions in cellular lipid/carbohydrate metabolism, signaling and F-actin regulation. J Steroid Biochem Mol Biol 2019; 192:105298. [PMID: 30716465 DOI: 10.1016/j.jsbmb.2019.01.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/21/2019] [Accepted: 01/25/2019] [Indexed: 12/20/2022]
Abstract
Oxysterol-binding protein (OSBP)-related proteins (ORPs) constitute a family of intracellular lipid-binding/transport proteins (LTPs) in eukaryotes. They typically have a modular structure comprising a lipid-binding domain and membrane targeting determinants, being thus suited for function at membrane contact sites. Among the mammalian ORPs, ORP2/OSBPL2 is the only member that only exists as a 'short' variant lacking a membrane-targeting pleckstrin homology domain. ORP2 is expressed ubiquitously and has been assigned a multitude of functions. Its OSBP-related domain binds cholesterol, oxysterols, and phosphoinositides, and its overexpression enhances cellular cholesterol efflux. Consistently, the latest observations suggest a function of ORP2 in cholesterol transport to the plasma membrane (PM) in exchange for phosphatidylinositol 4,5-bisphosphate (PI4,5P2), with significant impacts on the concentrations of PM cholesterol and PI4,5P2. On the other hand, ORP2 localizes at the surface of cytoplasmic lipid droplets (LDs) and at endoplasmic-reticulum-LD contact sites, and its depletion modifies cellular triglyceride (TG) metabolism. Study in an adrenocortical cell line further suggested a function of ORP2 in the synthesis of steroid hormones. Our recent knock-out of ORP2 in human hepatoma cells revealed its function in hepatocellular PI3K/Akt signaling, glucose and triglyceride metabolism, as well as in actin cytoskeletal regulation, cell adhesion, migration and proliferation. ORP2 was shown to interact physically with F-actin regulators such as DIAPH1, ARHGAP12, SEPT9 and MLC12, as well as with IQGAP1 and the Cdc37-Hsp90 chaperone complex controlling the activity of Akt. Interestingly, mutations in OSBPL2 encoding ORP2 are associated with autosomal dominant non-syndromic hearing loss, and the protein was found to localize in cochlear hair cell stereocilia. The functions assigned to ORP2 suggest that this protein, in concert with other LTPs, controls the subcellular distribution of cholesterol in various cell types and steroid hormone synthesis in adrenocortical cells. However, it also impacts cellular TG and carbohydrate metabolism and F-actin-dependent functions, revealing a bewildering spectrum of activities.
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Affiliation(s)
- Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, FI-00290, Helsinki, Finland; Department of Anatomy, Faculty of Medicine, FI-00014, University of Helsinki, Finland.
| | - Annika Koponen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, FI-00290, Helsinki, Finland; Department of Anatomy, Faculty of Medicine, FI-00014, University of Helsinki, Finland
| | - Amita Arora
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, FI-00290, Helsinki, Finland; Department of Anatomy, Faculty of Medicine, FI-00014, University of Helsinki, Finland
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