1
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Zhou XY, Lin B, Chen W, Cao RQ, Guo Y, Said A, Khan T, Zhang HL, Zhu YM. The brain protection of MLKL inhibitor necrosulfonamide against focal ischemia/reperfusion injury associating with blocking the nucleus and nuclear envelope translocation of MLKL and RIP3K. Front Pharmacol 2023; 14:1157054. [PMID: 37964865 PMCID: PMC10642205 DOI: 10.3389/fphar.2023.1157054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 07/27/2023] [Indexed: 11/16/2023] Open
Abstract
Mixed lineage kinase like protein (MLKL) is a key mediator of necroptosis. While previous studies highlighted the important role of MLKL as one of the central regulators of brain damage against acute ischemic neuronal injury, how the activation of MLKL mediates brain injuries and cell death remains unclear, especially in astrocytes. In a transient middle cerebral artery occlusion (tMCAO) rat model in vivo, and an oxygen-glucose deprivation and reoxygenation (OGD/Re) injury model in both primary cultured astrocytes and human astrocytes, we show that necrosulfonamide (NSA), a MLKL specific inhibitor, reduces infarction volume and improves neurological deficits in tMCAO-treated rats. In addition, NSA treatment, as well as RIP1K inhibitor Nec-1 or RIP3K inhibitor GSK-872 treatment, decreases the OGD/Re-induced leakage of LDH in both primary cultured astrocytes and human astrocytes. NSA treatment also reduces the number of propidium iodide (PI)-positive cells, and prevents the upregulation of necroptotic biomarkers such as MLKL/p-MLKL, RIP3K/p-RIP3K, and RIP1K/p-RIP1K in ischemic penumbra of cerebral cortex in tMCAO-treated rats or in OGD/Re-treated human astrocytes. Importantly, NSA treatment blocks both the nucleus and nuclear envelope localization of MLKL/p-MLKL and RIP3K/p-RIP3K in ischemic cerebral cortex induced by tMCAO. Similarly, Co-immunoprecipitation assay shows that NSA treatment decreases tMCAO- or OGD/Re- induced increased combination of MLKL and RIP3K in nuclear envelope of ischemic penumbra of cerebral cortex or of primary cultured astrocytes, respectively. RIP3K inhibitor GSK-872 also reduces tMCAO-induced increased combination of MLKL and RIP3K in nuclear envelope of ischemic penumbra of cerebral cortex. These data suggest NSA exerts protective effects against focal ischemia/reperfusion injury via inhibiting astrocytic necroptosis through preventing the upregulation of necroptotic kinases as well as blocking both the nucleus and nuclear envelope co-localization of p-MLKL and p-RIP3K. The translocation of p-MLKL, along with p-RIP3K, to the nuclear envelope and the nucleus may play a crucial role in MLKL-mediated necroptosis under ischemic conditions.
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Affiliation(s)
- Xian-Yong Zhou
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Suzhou Key Laboratory of Drug Research for Prevention and Treatment of Hyperlipidemic Diseases, Department of Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou, Jiangsu, China
| | - Bo Lin
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Suzhou Key Laboratory of Drug Research for Prevention and Treatment of Hyperlipidemic Diseases, Department of Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou, Jiangsu, China
| | - Wei Chen
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Suzhou Key Laboratory of Drug Research for Prevention and Treatment of Hyperlipidemic Diseases, Department of Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou, Jiangsu, China
| | - Rui-Qi Cao
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Suzhou Key Laboratory of Drug Research for Prevention and Treatment of Hyperlipidemic Diseases, Department of Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou, Jiangsu, China
| | - Yi Guo
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Suzhou Key Laboratory of Drug Research for Prevention and Treatment of Hyperlipidemic Diseases, Department of Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou, Jiangsu, China
| | - Ali Said
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Suzhou Key Laboratory of Drug Research for Prevention and Treatment of Hyperlipidemic Diseases, Department of Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou, Jiangsu, China
| | - Taous Khan
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, Islamabad, Pakistan
| | - Hui-Ling Zhang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Suzhou Key Laboratory of Drug Research for Prevention and Treatment of Hyperlipidemic Diseases, Department of Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou, Jiangsu, China
| | - Yong-Ming Zhu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Suzhou Key Laboratory of Drug Research for Prevention and Treatment of Hyperlipidemic Diseases, Department of Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou, Jiangsu, China
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2
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Tsuda N, Fukagawa R, Sueda S. Does the nuclear envelope retain its identity during mitosis? FEBS Lett 2023; 597:682-692. [PMID: 36528783 DOI: 10.1002/1873-3468.14568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/21/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022]
Abstract
During mitosis in metazoan species, the nuclear envelope (NE) undergoes breakdown, and its fragments are absorbed within the membranous network of the endoplasmic reticulum (ER). Past observations by fluorescence microscopy led researchers to think that the NE loses its identity when it is absorbed within the ER membrane. However, in our previous work, we developed a more specific labelling method and found evidence that the NE does not completely lose its identity during mitosis. In the present work, we conduct further experiments, the results of which support the idea that the NE partially retains its identity during mitosis.
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Affiliation(s)
- Natsumi Tsuda
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Japan
| | - Ryohei Fukagawa
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Japan
| | - Shinji Sueda
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Japan
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3
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Tamura K, Ueda H, Hara-Nishimura I. In vitro assembly of nuclear envelope in tobacco cultured cells. Nucleus 2021; 12:82-89. [PMID: 34030583 PMCID: PMC8158034 DOI: 10.1080/19491034.2021.1930681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 11/17/2022] Open
Abstract
The coordinated regulation of the nucelar envelope (NE) reassembly during cell division is an essential event. However, there is little information on the molecular components involved in NE assembly in plant cells. Here we developed an in vitro assay of NE assembly using tobacco BY-2 cultured cells. To start the NE assembly reaction, the demembranated nuclei and the S12 fraction (cytosol and microsomes) were mixed in the presence of GTP and ATP nucleotides. Time-course analysis indicated that tubule structures were extended from the microsomal vesicles that accumulated on the demembranated nuclei, and finally sealed the NE. Immunofluorescence confirmed that the assembled membrane contains a component of nuclear pore complex. The efficiency of the NE assembly is significantly inhibited by GTPγS that suppresses membrane fusion. This in-vitro assay system may elucidate the role of specific proteins and provide important insights into the molecular machinery of NE assembly in plant cells.
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Affiliation(s)
- Kentaro Tamura
- Department of Environmental and Life Sciences, School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka, Japan
| | - Haruko Ueda
- Faculty of Science and Engineering, Konan University, Kobe, Japan
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4
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Fluorescent Labeling of the Nuclear Envelope Without Relying on Inner Nuclear Membrane Proteins. Methods Mol Biol 2021; 2274:3-14. [PMID: 34050457 DOI: 10.1007/978-1-0716-1258-3_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The nuclear envelope (NE), a double membrane that separates nuclear components from the cytoplasm, undergoes a breakdown and reformation during cell division. To trace NE dynamics, the NE needs to be labeled with a fluorescent marker, and for this purpose, markers based on inner nuclear membrane (INM) proteins are normally used. However, NE labeling with INM proteins has some limitations. Here, we introduce a protocol for fluorescent labeling and imaging of NE that does not rely on INM proteins, along with protocols for simultaneously imaging two nuclear components and for time-lapse imaging of labeled cells.
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5
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Dazzoni R, Grélard A, Morvan E, Bouter A, Applebee CJ, Loquet A, Larijani B, Dufourc EJ. The unprecedented membrane deformation of the human nuclear envelope, in a magnetic field, indicates formation of nuclear membrane invaginations. Sci Rep 2020; 10:5147. [PMID: 32198481 PMCID: PMC7083927 DOI: 10.1038/s41598-020-61746-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/14/2020] [Indexed: 12/04/2022] Open
Abstract
Human nuclear membrane (hNM) invaginations are thought to be crucial in fusion, fission and remodeling of cells and present in many human diseases. There is however little knowledge, if any, about their lipid composition and dynamics. We therefore isolated nuclear envelope lipids from human kidney cells, analyzed their composition and determined the membrane dynamics after resuspension in buffer. The hNM lipid extract was composed of a complex mixture of phospholipids, with high amounts of phosphatidylcholines, phosphatidylinositols (PI) and cholesterol. hNM dynamics was determined by solid-state NMR and revealed that the lamellar gel-to-fluid phase transition occurs below 0 °C, reflecting the presence of elevated amounts of unsaturated fatty acid chains. Fluidity was higher than the plasma membrane, illustrating the dual action of Cholesterol (ordering) and PI lipids (disordering). The most striking result was the large magnetic field-induced membrane deformation allowing to determine the membrane bending elasticity, a property related to hydrodynamics of cells and organelles. Human Nuclear Lipid Membranes were at least two orders of magnitude more elastic than the classical plasma membrane suggesting a physical explanation for the formation of nuclear membrane invaginations.
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Affiliation(s)
- Régine Dazzoni
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France.,Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofísika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Axelle Grélard
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France
| | - Estelle Morvan
- Institut Européen de Chimie et Biologie, UMS3033, CNRS, Université Bordeaux, INSERM (US001), 2 rue Escarpit, Pessac, 33600, France
| | - Anthony Bouter
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France
| | - Christopher J Applebee
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofísika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, Spain.,Cell Biophysics Laboratory, Centre for Therapeutic Innovation & Department of Pharmacy and Pharmacology, & Department of Physics, University of Bath, Bath, United Kingdom
| | - Antoine Loquet
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France
| | - Banafshé Larijani
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofísika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, Spain. .,Cell Biophysics Laboratory, Centre for Therapeutic Innovation & Department of Pharmacy and Pharmacology, & Department of Physics, University of Bath, Bath, United Kingdom.
| | - Erick J Dufourc
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France.
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6
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Ulloa G, Hamati F, Dick A, Fitzgerald J, Mantell J, Verkade P, Collinson L, Arkill K, Larijani B, Poccia D. Lipid species affect morphology of endoplasmic reticulum: a sea urchin oocyte model of reversible manipulation. J Lipid Res 2019; 60:1880-1891. [PMID: 31548365 PMCID: PMC6824487 DOI: 10.1194/jlr.ra119000210] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 09/11/2019] [Indexed: 12/22/2022] Open
Abstract
The ER is a large multifunctional organelle of eukaryotic cells. Malfunction of the ER in various disease states, such as atherosclerosis, diabetes, cancer, Alzheimer’s and Parkinson’s and amyotrophic lateral sclerosis, often correlates with alterations in its morphology. The ER exhibits regionally variable membrane morphology that includes, at the extremes, large relatively flat surfaces and interconnected tubular structures highly curved in cross-section. ER morphology is controlled by shaping proteins that associate with membrane lipids. To investigate the role of these lipids, we developed a sea urchin oocyte model, a relatively quiescent cell in which the ER consists mostly of tubules. We altered levels of endogenous diacylglycerol (DAG), phosphatidylethanolamine (PtdEth), and phosphatidylcholine by microinjection of enzymes or lipid delivery by liposomes and evaluated shape changes with 2D and 3D confocal imaging and 3D electron microscopy. Decreases and increases in the levels of lipids such as DAG or PtdEth characterized by negative spontaneous curvature correlated with conversion to sheet structures or tubules, respectively. The effects of endogenous alterations of DAG were reversible upon exogenous delivery of lipids of negative spontaneous curvature. These data suggest that proteins require threshold amounts of such lipids and that localized deficiencies of the lipids could contribute to alterations of ER morphology. The oocyte modeling system should be beneficial to studies directed at understanding requirements of lipid species in interactions leading to alterations of organelle shaping.
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Affiliation(s)
| | - Fadi Hamati
- Department of Biology, Amherst College, Amherst, MA
| | | | | | - Judith Mantell
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | | | - Kenton Arkill
- School of Medicine, Faculty of Medicine and Health Sciences, University of Nottingham Medical School, Nottingham, United Kingdom
| | - Banafshe Larijani
- Centre for Therapeutic Innovation, Cell Biophysics Laboratory, Department of Pharmacy and Pharmacology and Department of Physics, University of Bath, Claverton Down, Bath, United Kingdom, and Cell Biophysics Laboratory, Ikerbasque, Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology (PiE) and Biophysics Institute (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain
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7
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Chung GHC, Domart MC, Peddie C, Mantell J, Mclaverty K, Arabiotorre A, Hodgson L, Byrne RD, Verkade P, Arkill K, Collinson LM, Larijani B. Acute depletion of diacylglycerol from the cis-Golgi affects localized nuclear envelope morphology during mitosis. J Lipid Res 2018; 59:1402-1413. [PMID: 29895700 PMCID: PMC6071775 DOI: 10.1194/jlr.m083899] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 06/12/2018] [Indexed: 12/28/2022] Open
Abstract
Dysregulation of nuclear envelope (NE) assembly results in various cancers; for example, renal and some lung carcinomas ensue due to NE malformation. The NE is a dynamic membrane compartment and its completion during mitosis is a highly regulated process, but the detailed mechanism still remains incompletely understood. Previous studies have found that isolated diacylglycerol (DAG)-containing vesicles are essential for completing the fusion of the NE in nonsomatic cells. We investigated the impact of DAG depletion from the cis-Golgi in mammalian cells on NE reassembly. Using advanced electron microscopy, we observed an enriched DAG population of vesicles at the vicinity of the NE gaps of telophase mammalian cells. We applied a mini singlet oxygen generator-C1-domain tag that localized DAG-enriched vesicles at the perinuclear region, which suggested the existence of NE fusogenic vesicles. We quantified the impact of Golgi-DAG depletion by measuring the in situ NE rim curvature of the reforming NE. The rim curvature in these cells was significantly reduced compared with controls, which indicated a localized defect in NE morphology. Our novel results demonstrate the significance of the role of DAG from the cis-Golgi for the regulation of NE assembly.
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Affiliation(s)
- Gary Hong Chun Chung
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology (PiE) and Biofísika Institute (UPV/EHU, CSIC), University of the Basque Country, Barrio Sarriena s/n 48940, Leioa, Spain
| | - Marie-Charlotte Domart
- Electron Microscopy Science Technology Platform, Francis Crick Institute, London, United Kingdom
| | - Christopher Peddie
- Electron Microscopy Science Technology Platform, Francis Crick Institute, London, United Kingdom
| | - Judith Mantell
- School of Biochemistry, Faculty of Biomedical Sciences, University of Bristol, Bristol, United Kingdom
| | - Kieran Mclaverty
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology (PiE) and Biofísika Institute (UPV/EHU, CSIC), University of the Basque Country, Barrio Sarriena s/n 48940, Leioa, Spain
- School of Biochemistry, Faculty of Biomedical Sciences, University of Bristol, Bristol, United Kingdom
| | - Angela Arabiotorre
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology (PiE) and Biofísika Institute (UPV/EHU, CSIC), University of the Basque Country, Barrio Sarriena s/n 48940, Leioa, Spain
| | - Lorna Hodgson
- School of Biochemistry, Faculty of Biomedical Sciences, University of Bristol, Bristol, United Kingdom
| | - Richard D Byrne
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology (PiE) and Biofísika Institute (UPV/EHU, CSIC), University of the Basque Country, Barrio Sarriena s/n 48940, Leioa, Spain
| | - Paul Verkade
- School of Biochemistry, Faculty of Biomedical Sciences, University of Bristol, Bristol, United Kingdom
- Wolfson Bioimaging Facility, University of Bristol, Bristol, United Kingdom
| | - Kenton Arkill
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology (PiE) and Biofísika Institute (UPV/EHU, CSIC), University of the Basque Country, Barrio Sarriena s/n 48940, Leioa, Spain
- Division of Cancer and Stem Cells, The Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Lucy M Collinson
- Electron Microscopy Science Technology Platform, Francis Crick Institute, London, United Kingdom
| | - Banafshé Larijani
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology (PiE) and Biofísika Institute (UPV/EHU, CSIC), University of the Basque Country, Barrio Sarriena s/n 48940, Leioa, Spain
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8
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Taniyama T, Tsuda N, Sueda S. Fluorescent Labeling of the Nuclear Envelope by Localizing Green Fluorescent Protein on the Inner Nuclear Membrane. ACS Chem Biol 2018; 13:1463-1469. [PMID: 29782140 DOI: 10.1021/acschembio.8b00219] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nuclear envelope (NE) is a double membrane that segregates nuclear components from the cytoplasm in eukaryotic cells. It is well-known that the NE undergoes a breakdown and reformation during mitosis in animal cells. However, the detailed mechanisms of the NE dynamics are not yet fully understood. Here, we propose a method for the fluorescent labeling of the NE in living cells, which enables the tracing of the NE dynamics during cell division under physiological conditions. In our method, labeling of the NE is accomplished by fixing green fluorescent protein carrying the nuclear localization signal on the inner nuclear membrane based on a unique biotinylation reaction from the archaeon Sulfolobus tokodaii. With this method, we observed HeLa cells during mitosis by confocal laser scanning microscopy and succeeded in clearly visualizing the difference in the timing of the formation of the NE and the nuclear lamina.
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Affiliation(s)
- Toshiyuki Taniyama
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502, Japan
| | - Natsumi Tsuda
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502, Japan
| | - Shinji Sueda
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502, Japan
- Research Center for Bio-microsensing Technology, Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu 804-8550, Japan
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9
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Affiliation(s)
- Douglas J. Richmond
- Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5–7 1350 Copenhagen Denmark
| | - Mikkel‐Holger S. Sinding
- Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5–7 1350 Copenhagen Denmark
- Natural History Museum University of Oslo P.O. Box 1172 Blindern NO‐0318 Oslo Norway
| | - M. Thomas P. Gilbert
- Section for Evolutionary Genomics Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5–7 1350 Copenhagen Denmark
- Trace and Environmental DNA Laboratory Department of Environment and Agriculture Curtin University Perth WA 6102 Australia
- NTNU University Museum NO‐7491 Trondheim Norway
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10
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Abstract
Most functions of eukaryotic cells are controlled by cellular membranes, which are not static entities but undergo frequent budding, fission, fusion, and sculpting reactions collectively referred to as membrane dynamics. Consequently, regulation of membrane dynamics is crucial for cellular functions. A key mechanism in such regulation is the reversible recruitment of cytosolic proteins or protein complexes to specific membranes at specific time points. To a large extent this recruitment is orchestrated by phosphorylated derivatives of the membrane lipid phosphatidylinositol, known as phosphoinositides. The seven phosphoinositides found in nature localize to distinct membrane domains and recruit distinct effectors, thereby contributing strongly to the maintenance of membrane identity. Many of the phosphoinositide effectors are proteins that control membrane dynamics, and in this review we discuss the functions of phosphoinositides in membrane dynamics during exocytosis, endocytosis, autophagy, cell division, cell migration, and epithelial cell polarity, with emphasis on protein effectors that are recruited by specific phosphoinositides during these processes.
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Affiliation(s)
- Kay O Schink
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, N-0379 Oslo, Norway; , .,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, N-0379 Oslo, Norway
| | - Kia-Wee Tan
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, N-0379 Oslo, Norway; , .,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, N-0379 Oslo, Norway
| | - Harald Stenmark
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, N-0379 Oslo, Norway; , .,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, N-0379 Oslo, Norway.,Centre of Molecular Inflammation Research, Faculty of Medicine, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
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11
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Hellberg T, Paßvogel L, Schulz KS, Klupp BG, Mettenleiter TC. Nuclear Egress of Herpesviruses: The Prototypic Vesicular Nucleocytoplasmic Transport. Adv Virus Res 2016; 94:81-140. [PMID: 26997591 DOI: 10.1016/bs.aivir.2015.10.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Herpesvirus particles mature in two different cellular compartments. While capsid assembly and packaging of the genomic linear double-stranded DNA occur in the nucleus, virion formation takes place in the cytoplasm by the addition of numerous tegument proteins as well as acquisition of the viral envelope by budding into cellular vesicles derived from the trans-Golgi network containing virally encoded glycoproteins. To gain access to the final maturation compartment, herpesvirus nucleocapsids have to cross a formidable barrier, the nuclear envelope (NE). Since the ca. 120 nm diameter capsids are unable to traverse via nuclear pores, herpesviruses employ a vesicular transport through both leaflets of the NE. This process involves proteins which support local dissolution of the nuclear lamina to allow access of capsids to the inner nuclear membrane (INM), drive vesicle formation from the INM and mediate inclusion of the capsid as well as scission of the capsid-containing vesicle (also designated as "primary virion"). Fusion of the vesicle membrane (i.e., the "primary envelope") with the outer nuclear membrane subsequently results in release of the nucleocapsid into the cytoplasm for continuing virion morphogenesis. While this process has long been thought to be unique for herpesviruses, a similar pathway for nuclear egress of macromolecular complexes has recently been observed in Drosophila. Thus, herpesviruses may have coopted a hitherto unrecognized cellular mechanism of vesicle-mediated nucleocytoplasmic transport. This could have far reaching consequences for our understanding of cellular functions as again unraveled by the study of viruses.
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Affiliation(s)
- Teresa Hellberg
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Lars Paßvogel
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Katharina S Schulz
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Barbara G Klupp
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany
| | - Thomas C Mettenleiter
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany.
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12
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Wang AS, Kundu A, Fong B, Fitzgerald J, Larijani B, Poccia D. A structural role for lipids in organelle shaping. THE BIOLOGICAL BULLETIN 2013; 224:218-226. [PMID: 23995745 DOI: 10.1086/bblv224n3p218] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The importance of proteins in shaping the membranes that define the perimeters of organelles is well documented. By forming cross-links, motors, or scaffolds or by inserting into membranes, proteins can harness energy to deform membranes, particularly when high degrees of curvature are necessitated-as in small membrane vesicles, tubules of the endoplasmic reticulum, the edges of endoplasmic reticulum sheets or Golgi apparatus cisternae, and membrane fusion intermediates (stalks). Here we propose that membrane lipids displaying negative curvature act in concert with membrane proteins to contribute to the alteration and maintenance of bending in biological membranes. We emphasize recent data from studies of sea urchin eggs and embryos and suggest how novel approaches can lead to future directions for investigating the roles of such lipids in vivo.
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Affiliation(s)
- Alan S Wang
- Department of Biology, Amherst College, Massachusetts 01002, USA
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13
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Domart MC, Hobday TMC, Peddie CJ, Chung GHC, Wang A, Yeh K, Jethwa N, Zhang Q, Wakelam MJO, Woscholski R, Byrne RD, Collinson LM, Poccia DL, Larijani B. Acute manipulation of diacylglycerol reveals roles in nuclear envelope assembly & endoplasmic reticulum morphology. PLoS One 2012; 7:e51150. [PMID: 23227247 PMCID: PMC3515572 DOI: 10.1371/journal.pone.0051150] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 10/29/2012] [Indexed: 12/16/2022] Open
Abstract
The functions and morphology of cellular membranes are intimately related and depend not only on their protein content but also on the repertoire of lipids that comprise them. In the absence of in vivo data on lipid asymmetry in endomembranes, it has been argued that motors, scaffolding proteins or integral membrane proteins rather than non-lamellar bilayer lipids such as diacylglycerol (DAG), are responsible for shaping of organelles, local membrane curvature and fusion. The effects of direct alteration of levels of such lipids remain predominantly uninvestigated. Diacylglycerol (DAG) is a well documented second messenger. Here we demonstrate two additional conserved functions of DAG: a structural role in organelle morphology, and a role in localised extreme membrane curvature required for fusion for which proteins alone are insufficient. Acute and inducible DAG depletion results in failure of the nuclear envelope (NE) to reform at mitosis and reorganisation of the ER into multi-lamellar sheets as revealed by correlative light and electron microscopy and 3D reconstructions. Remarkably, depleted cells divide without a complete NE, and unless rescued by 1,2 or 1,3 DAG soon die. Attenuation of DAG levels by enzyme microinjection into echinoderm eggs and embryos also results in alterations of ER morphology and nuclear membrane fusion. Our findings demonstrate that DAG is an in vivo modulator of organelle morphology in mammalian and echinoderm cells, indicating a fundamental role conserved across the deuterostome superphylum.
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Affiliation(s)
- Marie-Charlotte Domart
- Cell Biophysics Laboratory, London Research Institute, Cancer Research United Kingdom, London, United Kingdom
| | - Tina M. C. Hobday
- Cell Biophysics Laboratory, London Research Institute, Cancer Research United Kingdom, London, United Kingdom
| | - Christopher J. Peddie
- Electron Microscopy Unit, London Research Institute, Cancer Research United Kingdom, London, United Kingdom
| | - Gary H. C. Chung
- Cell Biophysics Laboratory, London Research Institute, Cancer Research United Kingdom, London, United Kingdom
| | - Alan Wang
- Department of Biology, Amherst College, Amherst, Massachusetts, United States of America
| | - Karen Yeh
- Department of Biology, Amherst College, Amherst, Massachusetts, United States of America
| | - Nirmal Jethwa
- Cell Biophysics Laboratory, London Research Institute, Cancer Research United Kingdom, London, United Kingdom
| | - Qifeng Zhang
- The Babraham Institute, Babraham Research Campus, Cambridge, United Kingdom
| | | | - Rudiger Woscholski
- Department of Chemistry, Faculty of Natural Sciences and Institute of Chemical Biology, Imperial College London, London, United Kingdom
| | - Richard D. Byrne
- Cell Biophysics Laboratory, London Research Institute, Cancer Research United Kingdom, London, United Kingdom
| | - Lucy M. Collinson
- Electron Microscopy Unit, London Research Institute, Cancer Research United Kingdom, London, United Kingdom
| | - Dominic L. Poccia
- Department of Biology, Amherst College, Amherst, Massachusetts, United States of America
| | - Banafshé Larijani
- Cell Biophysics Laboratory, London Research Institute, Cancer Research United Kingdom, London, United Kingdom
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14
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Dynamic assembly of brambleberry mediates nuclear envelope fusion during early development. Cell 2012; 150:521-32. [PMID: 22863006 DOI: 10.1016/j.cell.2012.05.048] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 05/16/2012] [Accepted: 05/18/2012] [Indexed: 12/25/2022]
Abstract
To accommodate the large cells following zygote formation, early blastomeres employ modified cell divisions. Karyomeres are one such modification, mitotic intermediates wherein individual chromatin masses are surrounded by nuclear envelope; the karyomeres then fuse to form a single mononucleus. We identified brambleberry, a maternal-effect zebrafish mutant that disrupts karyomere fusion, resulting in formation of multiple micronuclei. As karyomeres form, Brambleberry protein localizes to the nuclear envelope, with prominent puncta evident near karyomere-karyomere interfaces corresponding to membrane fusion sites. brambleberry corresponds to an unannotated gene with similarity to Kar5p, a protein that participates in nuclear fusion in yeast. We also demonstrate that Brambleberry is required for pronuclear fusion following fertilization in zebrafish. Our studies provide insight into the machinery required for karyomere fusion and suggest that specialized proteins are necessary for proper nuclear division in large dividing blastomeres.
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15
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Dynamics of PLCγ and Src family kinase 1 interactions during nuclear envelope formation revealed by FRET-FLIM. PLoS One 2012; 7:e40669. [PMID: 22848394 PMCID: PMC3404105 DOI: 10.1371/journal.pone.0040669] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 06/11/2012] [Indexed: 01/10/2023] Open
Abstract
The nuclear envelope (NE) breaks down and reforms during each mitotic cycle. A similar process happens to the sperm NE following fertilisation. The formation of the NE in both these circumstances involves endoplasmic reticulum membranes enveloping the chromatin, but PLCγ-dependent membrane fusion events are also essential. Here we demonstrate the activation of PLCγ by a Src family kinase (SFK1) during NE assembly. We show by time-resolved FRET for the first time the direct in vivo interaction and temporal regulation of PLCγ and SFK1 in sea urchins. As a prerequisite for protein activation, there is a rapid phosphorylation of PLCγ on its Y783 residue in response to GTP in vitro. This phosphorylation is dependent upon SFK activity; thus Y783 phosphorylation and NE assembly are susceptible to SFK inhibition. Y783 phosphorylation is also observed on the surface of the male pronucleus (MPN) in vivo during NE formation. Together the corroborative in vivo and in vitro data demonstrate the phosphorylation and activation of PLCγ by SFK1 during NE assembly. We discuss the potential generality of such a mechanism.
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16
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Goñi FM, Montes LR, Alonso A. Phospholipases C and sphingomyelinases: Lipids as substrates and modulators of enzyme activity. Prog Lipid Res 2012; 51:238-66. [DOI: 10.1016/j.plipres.2012.03.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 03/23/2012] [Accepted: 03/26/2012] [Indexed: 11/30/2022]
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17
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Larijani B, Poccia DL. Effects of Phosphoinositides and Their Derivatives on Membrane Morphology and Function. Curr Top Microbiol Immunol 2012; 362:99-110. [DOI: 10.1007/978-94-007-5025-8_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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18
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Zhendre V, Grélard A, Garnier-LHomme M, Buchoux S, Larijani B, Dufourc EJ. Key role of polyphosphoinositides in dynamics of fusogenic nuclear membrane vesicles. PLoS One 2011; 6:e23859. [PMID: 21931619 PMCID: PMC3169559 DOI: 10.1371/journal.pone.0023859] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 07/26/2011] [Indexed: 11/18/2022] Open
Abstract
The role of phosphoinositides has been thoroughly described in many signalling and membrane trafficking events but their function as modulators of membrane structure and dynamics in membrane fusion has not been investigated. We have reconstructed models that mimic the composition of nuclear envelope precursor membranes with naturally elevated amounts of phosphoinositides. These fusogenic membranes (membrane vesicle 1(MV1) and nuclear envelope remnants (NER) are critical for the assembly of the nuclear envelope. Phospholipids, cholesterol, and polyphosphoinositides, with polyunsaturated fatty acid chains that were identified in the natural nuclear membranes by lipid mass spectrometry, have been used to reconstruct complex model membranes mimicking nuclear envelope precursor membranes. Structural and dynamic events occurring in the membrane core and at the membrane surface were monitored by solid-state deuterium and phosphorus NMR. "MV1-like" (PC∶PI∶PIP∶PIP(2), 30∶20∶18∶12, mol%) membranes that exhibited high levels of PtdIns, PtdInsP and PtdInsP(2) had an unusually fluid membrane core (up to 20% increase, compared to membranes with low amounts of phosphoinositides to mimic the endoplasmic reticulum). "NER-like" (PC∶CH∶PI∶PIP∶PIP(2), 28∶42∶16∶7∶7, mol%) membranes containing high amounts of both cholesterol and phosphoinositides exhibited liquid-ordered phase properties, but with markedly lower rigidity (10-15% decrease). Phosphoinositides are the first lipids reported to counterbalance the ordering effect of cholesterol. At the membrane surface, phosphoinositides control the orientation dynamics of other lipids in the model membranes, while remaining unchanged themselves. This is an important finding as it provides unprecedented mechanistic insight into the role of phosphoinositides in membrane dynamics. Biological implications of our findings and a model describing the roles of fusogenic membrane vesicles are proposed.
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Affiliation(s)
- Vanessa Zhendre
- Chemistry and Biology of Membranes and Nanoobjects (CBMN), UMR5248 - CNRS-Université Bordeaux-Institut Polytechnique de Bordeaux, Pessac, France
- Cell Biophysics Laboratory, Lincoln's Inn Fields Laboratories, Cancer Research UK, London, United Kingdom
| | - Axelle Grélard
- Chemistry and Biology of Membranes and Nanoobjects (CBMN), UMR5248 - CNRS-Université Bordeaux-Institut Polytechnique de Bordeaux, Pessac, France
| | - Marie Garnier-LHomme
- Chemistry and Biology of Membranes and Nanoobjects (CBMN), UMR5248 - CNRS-Université Bordeaux-Institut Polytechnique de Bordeaux, Pessac, France
- Cell Biophysics Laboratory, Lincoln's Inn Fields Laboratories, Cancer Research UK, London, United Kingdom
| | - Sébastien Buchoux
- UMR 6022 - Génie Enzymatique et Cellulaire, Université Picardie Jules Verne (UPJV), Amiens, France
| | - Banafshé Larijani
- Cell Biophysics Laboratory, Lincoln's Inn Fields Laboratories, Cancer Research UK, London, United Kingdom
| | - Erick J. Dufourc
- Chemistry and Biology of Membranes and Nanoobjects (CBMN), UMR5248 - CNRS-Université Bordeaux-Institut Polytechnique de Bordeaux, Pessac, France
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19
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Rafikova ER, Melikov K, Chernomordik LV. Cytosol-dependent membrane fusion in ER, nuclear envelope and nuclear pore assembly: biological implications. Nucleus 2011; 1:487-91. [PMID: 21327091 DOI: 10.4161/nucl.1.6.13514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 08/19/2010] [Accepted: 09/03/2010] [Indexed: 12/26/2022] Open
Abstract
Endoplasmic reticulum and nuclear envelope rearrangements after mitosis are often studied in the reconstitution system based on Xenopus egg extract. In our recent work we partially replaced the membrane vesicles in the reconstitution mix with protein-free liposomes to explore the relative contributions of cytosolic and transmembrane proteins. Here we discuss our finding that cytosolic proteins mediate fusion between membranes lacking functional transmembrane proteins and the role of membrane fusion in endoplasmic reticulum and nuclear envelope reorganization. Cytosol-dependent liposome fusion has allowed us to restore, without adding transmembrane nucleoporins, functionality of nuclear pores, their spatial distribution and chromatin decondensation in nuclei formed at insufficient amounts of membrane material and characterized by only partial decondensation of chromatin and lack of nuclear transport. Both the mechanisms and the biological implications of the discovered coupling between spatial distribution of nuclear pores, chromatin decondensation and nuclear transport are discussed.
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Affiliation(s)
- Elvira R Rafikova
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, USA
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20
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Dumas F, Byrne RD, Vincent B, Hobday TMC, Poccia DL, Larijani B. Spatial regulation of membrane fusion controlled by modification of phosphoinositides. PLoS One 2010; 5:e12208. [PMID: 20808914 PMCID: PMC2923163 DOI: 10.1371/journal.pone.0012208] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 07/20/2010] [Indexed: 01/07/2023] Open
Abstract
Membrane fusion plays a central role in many cell processes from vesicular
transport to nuclear envelope reconstitution at mitosis but the mechanisms that
underlie fusion of natural membranes are not well understood. Studies with
synthetic membranes and theoretical considerations indicate that accumulation of
lipids characterised by negative curvature such as diacylglycerol (DAG)
facilitate fusion. However, the specific role of lipids in membrane fusion of
natural membranes is not well established. Nuclear envelope (NE) assembly was
used as a model for membrane fusion. A natural membrane population highly
enriched in the enzyme and substrate needed to produce DAG has been isolated and
is required for fusions leading to nuclear envelope formation, although it
contributes only a small amount of the membrane eventually incorporated into the
NE. It was postulated to initiate and regulate membrane fusion. Here we use a
multidisciplinary approach including subcellular membrane purification,
fluorescence spectroscopy and Förster resonance energy transfer
(FRET)/two-photon fluorescence lifetime imaging microscopy (FLIM) to demonstrate
that initiation of vesicle fusion arises from two unique sites where these
vesicles bind to chromatin. Fusion is subsequently propagated to the endoplasmic
reticulum-derived membranes that make up the bulk of the NE to ultimately
enclose the chromatin. We show how initiation of multiple vesicle fusions can be
controlled by localised production of DAG and propagated bidirectionally.
Phospholipase C (PLCγ), GTP hydrolysis and
(phosphatidylinsositol-(4,5)-bisphosphate (PtdIns(4,5)P2) are
required for the latter process. We discuss the general implications of membrane
fusion regulation and spatial control utilising such a mechanism.
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Affiliation(s)
- Fabrice Dumas
- Cell Biophysics Laboratory, Lincoln's Inn Fields Laboratories,
Cancer Research UK, London, United Kingdom
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale),
Toulouse, France
- Université de Toulouse, UPS, IPBS (Institut de Pharmacologie
et de Biologie Structurale), Toulouse, France
| | - Richard D. Byrne
- Cell Biophysics Laboratory, Lincoln's Inn Fields Laboratories,
Cancer Research UK, London, United Kingdom
| | - Ben Vincent
- Department of Biology, Amherst College, Amherst, Massachusetts, United
States of America
| | - Tina M. C. Hobday
- Cell Biophysics Laboratory, Lincoln's Inn Fields Laboratories,
Cancer Research UK, London, United Kingdom
| | - Dominic L. Poccia
- Department of Biology, Amherst College, Amherst, Massachusetts, United
States of America
- * E-mail: (BL); (DLP)
| | - Banafshé Larijani
- Cell Biophysics Laboratory, Lincoln's Inn Fields Laboratories,
Cancer Research UK, London, United Kingdom
- * E-mail: (BL); (DLP)
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21
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Liu Y, Bankaitis VA. Phosphoinositide phosphatases in cell biology and disease. Prog Lipid Res 2010; 49:201-17. [PMID: 20043944 PMCID: PMC2873057 DOI: 10.1016/j.plipres.2009.12.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/03/2009] [Accepted: 12/03/2009] [Indexed: 01/10/2023]
Abstract
Phosphoinositides are essential signaling molecules linked to a diverse array of cellular processes in eukaryotic cells. The metabolic interconversions of these phospholipids are subject to exquisite spatial and temporal regulation executed by arrays of phosphatidylinositol (PtdIns) and phosphoinositide-metabolizing enzymes. These include PtdIns- and phosphoinositide-kinases that drive phosphoinositide synthesis, and phospholipases and phosphatases that regulate phosphoinositide degradation. In the past decade, phosphoinositide phosphatases have emerged as topics of particular interest. This interest is driven by the recent appreciation that these enzymes represent primary mechanisms for phosphoinositide degradation, and because of their ever-increasing connections with human diseases. Herein, we review the biochemical properties of six major phosphoinositide phosphatases, the functional involvements of these enzymes in regulating phosphoinositide metabolism, the pathologies that arise from functional derangements of individual phosphatases, and recent ideas concerning the involvements of phosphoinositide phosphatases in membrane traffic control.
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Affiliation(s)
- Yang Liu
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090, USA
| | - Vytas A. Bankaitis
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090, USA
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22
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Abstract
Membrane fusion underlies many cellular events, including secretion, exocytosis, endocytosis, organelle reconstitution, transport from endoplasmic reticulum to Golgi and nuclear envelope formation. A large number of investigations into membrane fusion indicate various roles for individual members of the phosphoinositide class of membrane lipids. We first review the phosphoinositides as membrane recognition sites and their regulatory functions in membrane fusion. We then consider how modulation of phosphoinositides and their products may affect the structure and dynamics of natural membranes facilitating fusion. These diverse roles underscore the importance of these phospholipids in the fusion of biological membranes.
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