101
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Control of plasma membrane lipid homeostasis by the extended synaptotagmins. Nat Cell Biol 2016; 18:504-15. [PMID: 27065097 PMCID: PMC4848133 DOI: 10.1038/ncb3339] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 03/11/2016] [Indexed: 02/08/2023]
Abstract
Acute metabolic changes of plasma membrane (PM) lipids, such as those mediating signaling reactions, are rapidly compensated by homeostatic responses whose molecular basis is poorly understood. Here we show that the Extended-Synaptotagmins (E-Syts), ER proteins which function as PI(4,5)P2 and Ca2+-regulated tethers to the PM, participate in these responses. E-Syts transfer glycerolipids between bilayers in vitro and such transfer requires Ca2+ and their SMP domain, a lipid-harboring module. Genome edited cells lacking E-Syts do not exhibit abnormalities in the major glycerolipids at rest, but display enhanced and sustained accumulation of PM diacylglycerol (DAG) upon PI(4,5)P2 hydrolysis by PLC activation, which can be rescued by expression of E-Syt1, but not by mutant E-Syt1 lacking the SMP domain. The formation of E-Syts-dependent ER-PM tethers in response to stimuli that cleave PI(4,5)P2 and elevate Ca2+ may help reverse accumulation of DAG in the PM by transferring it to the ER for metabolic recycling.
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102
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Vacuole membrane contact sites and domains: emerging hubs to coordinate organelle function with cellular metabolism. Biochem Soc Trans 2016; 44:528-33. [DOI: 10.1042/bst20150277] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Indexed: 02/07/2023]
Abstract
Eukaryotic cells rely on a set of membrane-enclosed organelles to perform highly efficient reactions in an optimized environment. Trafficking of molecules via vesicular carriers and membrane contact sites (MCS) allow the coordination between these compartments, though the precise mechanisms are still enigmatic. Among the cellular organelles, the lysosome/vacuole stands out as a central hub, where multiple pathways merge. Importantly, the delivered material is degraded and the monomers are recycled for further usage, which explains its wide variety of roles in controlling cellular metabolism. We will highlight recent advances in the field by focusing on the yeast vacuole as a model system to understand lysosomal function in general.
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103
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Sparkes I. Using Optical Tweezers to Characterize Physical Tethers at Membrane Contact Sites: Grab It, Pull It, Set It Free? Front Cell Dev Biol 2016; 4:22. [PMID: 27066480 PMCID: PMC4809892 DOI: 10.3389/fcell.2016.00022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 03/11/2016] [Indexed: 11/17/2022] Open
Affiliation(s)
- Imogen Sparkes
- Biosciences, College of Life and Environmental Sciences, University of ExeterExeter, UK
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104
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New Insight Into the Roles of Membrane Microdomains in Physiological Activities of Fungal Cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 325:119-80. [PMID: 27241220 DOI: 10.1016/bs.ircmb.2016.02.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The organization of biological membranes into structurally and functionally distinct lateral microdomains is generally accepted. From bacteria to mammals, laterally compartmentalized membranes seem to be a vital attribute of life. The crucial fraction of our current knowledge about the membrane microdomains has been gained from studies on fungi. In this review we summarize the evidence of the microdomain organization of membranes from fungal cells, with accent on their enormous diversity in composition, temporal dynamics, modes of formation, and recognized engagement in the cell physiology. A special emphasis is laid on the fact that in addition to their other biological functions, membrane microdomains also mediate the communication among different membranes within a eukaryotic cell and coordinate their functions. Involvement of fungal membrane microdomains in stress sensing, regulation of lipid homeostasis, and cell differentiation is discussed more in detail.
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105
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Quon E, Beh CT. Membrane Contact Sites: Complex Zones for Membrane Association and Lipid Exchange. Lipid Insights 2016; 8:55-63. [PMID: 26949334 PMCID: PMC4772907 DOI: 10.4137/lpi.s37190] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 01/28/2016] [Accepted: 01/31/2016] [Indexed: 11/07/2022] Open
Abstract
Lipid transport between membranes within cells involves vesicle and protein carriers, but as agents of nonvesicular lipid transfer, the role of membrane contact sites has received increasing attention. As zones for lipid metabolism and exchange, various membrane contact sites mediate direct associations between different organelles. In particular, membrane contact sites linking the plasma membrane (PM) and the endoplasmic reticulum (ER) represent important regulators of lipid and ion transfer. In yeast, cortical ER is stapled to the PM through membrane-tethering proteins, which establish a direct connection between the membranes. In this review, we consider passive and facilitated models for lipid transfer at PM–ER contact sites. Besides the tethering proteins, we examine the roles of an additional repertoire of lipid and protein regulators that prime and propagate PM–ER membrane association. We conclude that instead of being simple mediators of membrane association, regulatory components of membrane contact sites have complex and multilayered functions.
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Affiliation(s)
- Evan Quon
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Christopher T Beh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.; Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC, Canada
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106
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The TULIP superfamily of eukaryotic lipid-binding proteins as a mediator of lipid sensing and transport. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:913-923. [PMID: 26825693 DOI: 10.1016/j.bbalip.2016.01.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 01/16/2016] [Accepted: 01/25/2016] [Indexed: 01/28/2023]
Abstract
The tubular lipid-binding (TULIP) superfamily has emerged in recent years as a major mediator of lipid sensing and transport in eukaryotes. It currently encompasses three protein families, SMP-like, BPI-like, and Takeout-like, which share a common fold. This fold consists of a long helix wrapped in a highly curved anti-parallel β-sheet, enclosing a central, lipophilic cavity. The SMP-like proteins, which include subunits of the ERMES complex and the extended synaptotagmins (E-Syts), appear to be mainly located at membrane contacts sites (MCSs) between organelles, mediating inter-organelle lipid exchange. The BPI-like proteins, which include the bactericidal/permeability-increasing protein (BPI), the LPS (lipopolysaccharide)-binding protein (LBP), the cholesteryl ester transfer protein (CETP), and the phospholipid transfer protein (PLTP), are either involved in innate immunity against bacteria through their ability to sense lipopolysaccharides, as is the case for BPI and LBP, or in lipid exchange between lipoprotein particles, as is the case for CETP and PLTP. The Takeout-like proteins, which are comprised of insect juvenile hormone-binding proteins and arthropod allergens, transport, where known, lipid hormones to target tissues during insect development. In all cases, the activity of these proteins is underpinned by their ability to bind large, hydrophobic ligands in their central cavity and segregate them away from the aqueous environment. Furthermore, where they are involved in lipid exchange, recent structural studies have highlighted their ability to establish lipophilic, tubular channels, either between organelles in the case of SMP domains or between lipoprotein particles in the case of CETP. Here, we review the current knowledge on the structure, versatile functions, and evolution of the TULIP superfamily. We propose a deep evolutionary split in this superfamily, predating the Last Eukaryotic Common Ancestor, between the SMP-like proteins, which act on lipids endogenous to the cell, and the BPI-like proteins (including the Takeout-like proteins of arthropods), which act on exogenous lipids. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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107
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Dong L, Jongedijk E, Bouwmeester H, Van Der Krol A. Monoterpene biosynthesis potential of plant subcellular compartments. THE NEW PHYTOLOGIST 2016; 209:679-90. [PMID: 26356766 DOI: 10.1111/nph.13629] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Accepted: 08/03/2015] [Indexed: 05/03/2023]
Abstract
Subcellular monoterpene biosynthesis capacity based on local geranyl diphosphate (GDP) availability or locally boosted GDP production was determined for plastids, cytosol and mitochondria. A geraniol synthase (GES) was targeted to plastids, cytosol, or mitochondria. Transient expression in Nicotiana benthamiana indicated local GDP availability for each compartment but resulted in different product levels. A GDP synthase from Picea abies (PaGDPS1) was shown to boost GDP production. PaGDPS1 was also targeted to plastids, cytosol or mitochondria and PaGDPS1 and GES were coexpressed in all possible combinations. Geraniol and geraniol-derived products were analyzed by GC-MS and LC-MS, respectively. GES product levels were highest for plastid-targeted GES, followed by mitochondrial- and then cytosolic-targeted GES. For each compartment local boosting of GDP biosynthesis increased GES product levels. GDP exchange between compartments is not equal: while no GDP is exchanged from the cytosol to the plastids, 100% of GDP in mitochondria can be exchanged to plastids, while only 7% of GDP from plastids is available for mitochondria. This suggests a direct exchange mechanism for GDP between plastids and mitochondria. Cytosolic PaGDPS1 competes with plastidial GES activity, suggesting an effective drain of isopentenyl diphosphate from the plastids to the cytosol.
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Affiliation(s)
- Lemeng Dong
- Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands
| | - Esmer Jongedijk
- Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands
| | - Harro Bouwmeester
- Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands
| | - Alexander Van Der Krol
- Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands
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108
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Abstract
The fundamental mechanisms of protein and lipid organization at the plasma membrane have continued to engage researchers for decades. Among proposed models, one idea has been particularly successful which assumes that sterol-dependent nanoscopic phases of different lipid chain order compartmentalize proteins, thereby modulating protein functionality. This model of membrane rafts has sustainably sparked the fields of membrane biophysics and biology, and shifted membrane lipids into the spotlight of research; by now, rafts have become an integral part of our terminology to describe a variety of cell biological processes. But is the evidence clear enough to continue supporting a theoretical concept which has resisted direct proof by observation for nearly twenty years? In this essay, we revisit findings that gave rise to and substantiated the raft hypothesis, discuss its impact on recent studies, and present alternative mechanisms to account for plasma membrane heterogeneity.
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Affiliation(s)
- Eva Sevcsik
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
| | - Gerhard J Schütz
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
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109
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Chiapparino A, Maeda K, Turei D, Saez-Rodriguez J, Gavin AC. The orchestra of lipid-transfer proteins at the crossroads between metabolism and signaling. Prog Lipid Res 2015; 61:30-9. [PMID: 26658141 DOI: 10.1016/j.plipres.2015.10.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 10/15/2015] [Indexed: 01/12/2023]
Abstract
Within the eukaryotic cell, more than 1000 species of lipids define a series of membranes essential for cell function. Tightly controlled systems of lipid transport underlie the proper spatiotemporal distribution of membrane lipids, the coordination of spatially separated lipid metabolic pathways, and lipid signaling mediated by soluble proteins that may be localized some distance away from membranes. Alongside the well-established vesicular transport of lipids, non-vesicular transport mediated by a group of proteins referred to as lipid-transfer proteins (LTPs) is emerging as a key mechanism of lipid transport in a broad range of biological processes. More than a hundred LTPs exist in humans and these can be divided into at least ten protein families. LTPs are widely distributed in tissues, organelles and membrane contact sites (MCSs), as well as in the extracellular space. They all possess a soluble and globular domain that encapsulates a lipid monomer and they specifically bind and transport a wide range of lipids. Here, we present the most recent discoveries in the functions and physiological roles of LTPs, which have expanded the playground of lipids into the aqueous spaces of cells.
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Affiliation(s)
- Antonella Chiapparino
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Kenji Maeda
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Denes Turei
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany; European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute (EBI), Cambridge CB10 1SD, UK
| | - Julio Saez-Rodriguez
- European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute (EBI), Cambridge CB10 1SD, UK
| | - Anne-Claude Gavin
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany; European Molecular Biology Laboratory (EMBL), Molecular Medicine Partnership Unit (MMPU), Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
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110
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Masuda M, Oshima A, Noguchi T, Kagiwada S. Induction of intranuclear membranes by overproduction of Opi1p and Scs2p, regulators for yeast phospholipid biosynthesis, suggests a mechanism for Opi1p nuclear translocation. J Biochem 2015; 159:351-61. [PMID: 26590299 DOI: 10.1093/jb/mvv105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/24/2015] [Indexed: 12/17/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, the expression of phospholipid biosynthetic genes is suppressed by the Opi1p negative regulator. Opi1p enters into the nucleoplasm from the nuclear membrane to suppress the gene expression under repressing conditions. The binding of Opi1p to the nuclear membrane requires an integral membrane protein, Scs2p and phosphatidic acid (PA). Although it is demonstrated that the association of Opi1p with membranes is affected by PA levels, how Opi1p dissociates from Scs2p is unknown. Here, we found that fluorescently labelled Opi1p accumulated on a perinuclear region in an Scs2p-dependent manner. Electron microscopic analyses indicated that the perinuclear region consists of intranuclear membranes, which may be formed by the invagination of the nuclear membrane due to the accumulation of Opi1p and Scs2p in a restricted area. As expected, localization of Opi1p and Scs2p in the intranuclear membranes was detected by immunoelectron microscopy. Biochemical analysis showed that Opi1p recovered in the membrane fraction was detergent insoluble while Scs2p was soluble, implying that Opi1p behaves differently from Scs2p in the fraction. We hypothesize that Opi1p dissociates from Scs2p after targeting to the nuclear membrane, making it possible to be released from the membrane quickly when PA levels decrease.
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Affiliation(s)
- Miki Masuda
- Department of Biological Sciences, Faculty of Science, Nara Women's University, Nara 630-8506, Japan
| | - Ayaka Oshima
- Department of Biological Sciences, Faculty of Science, Nara Women's University, Nara 630-8506, Japan
| | - Tetsuko Noguchi
- Department of Biological Sciences, Faculty of Science, Nara Women's University, Nara 630-8506, Japan
| | - Satoshi Kagiwada
- Department of Biological Sciences, Faculty of Science, Nara Women's University, Nara 630-8506, Japan
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111
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Kentala H, Weber-Boyvat M, Olkkonen VM. OSBP-Related Protein Family: Mediators of Lipid Transport and Signaling at Membrane Contact Sites. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 321:299-340. [PMID: 26811291 DOI: 10.1016/bs.ircmb.2015.09.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Oxysterol-binding protein (OSBP) and its related protein homologs, ORPs, constitute a conserved family of lipid-binding/transfer proteins (LTPs) expressed ubiquitously in eukaryotes. The ligand-binding domain of ORPs accommodates cholesterol and oxysterols, but also glycerophospholipids, particularly phosphatidylinositol-4-phosphate (PI4P). ORPs have been implicated as intracellular lipid sensors or transporters. Most ORPs carry targeting determinants for the endoplasmic reticulum (ER) and non-ER organelle membrane. ORPs are located and function at membrane contact sites (MCSs), at which ER is closely apposed with other organelle limiting membranes. Such sites have roles in lipid transport and metabolism, control of Ca(2+) fluxes, and signaling events. ORPs are postulated either to transport lipids over MCSs to maintain the distinct lipid compositions of organelle membranes, or to control the activity of enzymes/protein complexes with functions in signaling and lipid metabolism. ORPs may transfer PI4P and another lipid class bidirectionally. Transport of PI4P followed by its hydrolysis would in this model provide the energy for transfer of the other lipid against its concentration gradient. Control of organelle lipid compositions by OSBP/ORPs is important for the life cycles of several pathogenic viruses. Targeting ORPs with small-molecular antagonists is proposed as a new strategy to combat viral infections. Several ORPs are reported to modulate vesicle transport along the secretory or endocytic pathways. Moreover, antagonists of certain ORPs inhibit cancer cell proliferation. Thus, ORPs are LTPs, which mediate interorganelle lipid transport and coordinate lipid signals with a variety of cellular regimes.
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Affiliation(s)
- Henriikka Kentala
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland
| | - Marion Weber-Boyvat
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland
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112
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Olkkonen VM. OSBP-Related Protein Family in Lipid Transport Over Membrane Contact Sites. Lipid Insights 2015; 8:1-9. [PMID: 26715851 PMCID: PMC4685180 DOI: 10.4137/lpi.s31726] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/03/2015] [Accepted: 09/06/2015] [Indexed: 12/12/2022] Open
Abstract
Increasing evidence suggests that oxysterol-binding protein-related proteins (ORPs) localize at membrane contact sites, which are high-capacity platforms for inter-organelle exchange of small molecules and information. ORPs can simultaneously associate with the two apposed membranes and transfer lipids across the interbilayer gap. Oxysterol-binding protein moves cholesterol from the endoplasmic reticulum to trans-Golgi, driven by the retrograde transport of phosphatidylinositol-4-phosphate (PI4P). Analogously, yeast Osh6p mediates the transport of phosphatidylserine from the endoplasmic reticulum to the plasma membrane in exchange for PI4P, and ORP5 and -8 are suggested to execute similar functions in mammalian cells. ORPs may share the capacity to bind PI4P within their ligand-binding domain, prompting the hypothesis that bidirectional transport of a phosphoinositide and another lipid may be a common theme among the protein family. This model, however, needs more experimental support and does not exclude a function of ORPs in lipid signaling.
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Affiliation(s)
- Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland. ; Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland
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113
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Henne WM, Zhu L, Balogi Z, Stefan C, Pleiss JA, Emr SD. Mdm1/Snx13 is a novel ER-endolysosomal interorganelle tethering protein. J Cell Biol 2015; 210:541-51. [PMID: 26283797 PMCID: PMC4539980 DOI: 10.1083/jcb.201503088] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Mdm1 is a novel interorganelle tethering protein that localizes to yeast ER–vacuole/lysosome junctions, and Mdm1 truncations analogous to disease-associated Snx14 alleles fail to tether the ER and vacuole and perturb sphingolipid metabolism. Although endolysosomal trafficking is well defined, how it is regulated and coordinates with cellular metabolism is unclear. To identify genes governing endolysosomal dynamics, we conducted a global fluorescence-based screen to reveal endomembrane effector genes. Screening implicated Phox (PX) domain–containing protein Mdm1 in endomembrane dynamics. Surprisingly, we demonstrate that Mdm1 is a novel interorganelle tethering protein that localizes to endoplasmic reticulum (ER)–vacuole/lysosome membrane contact sites (MCSs). We show that Mdm1 is ER anchored and contacts the vacuole surface in trans via its lipid-binding PX domain. Strikingly, overexpression of Mdm1 induced ER–vacuole hypertethering, underscoring its role as an interorganelle tether. We also show that Mdm1 and its paralogue Ydr179w-a (named Nvj3 in this study) localize to ER–vacuole MCSs independently of established tether Nvj1. Finally, we find that Mdm1 truncations analogous to neurological disease–associated SNX14 alleles fail to tether the ER and vacuole and perturb sphingolipid metabolism. Our work suggests that human Mdm1 homologues may play previously unappreciated roles in interorganelle communication and lipid metabolism.
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Affiliation(s)
- W Mike Henne
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Lu Zhu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Zsolt Balogi
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Christopher Stefan
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, England, UK
| | - Jeffrey A Pleiss
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Scott D Emr
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
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114
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Wijdeven RH, Jongsma MLM, Neefjes J, Berlin I. ER contact sites direct late endosome transport. Bioessays 2015; 37:1298-302. [DOI: 10.1002/bies.201500095] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Ruud H. Wijdeven
- Division of Cell Biology; The Netherlands Cancer Institute; Amsterdam The Netherlands
| | - Marlieke L. M. Jongsma
- Department of Immunopathology; Sanquin Research and Landsteiner Laboratory AMC/UvA; Amsterdam The Netherlands
| | - Jacques Neefjes
- Division of Cell Biology; The Netherlands Cancer Institute; Amsterdam The Netherlands
| | - Ilana Berlin
- Division of Cell Biology; The Netherlands Cancer Institute; Amsterdam The Netherlands
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115
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Jing J, He L, Sun A, Quintana A, Ding Y, Ma G, Tan P, Liang X, Zheng X, Chen L, Shi X, Zhang SL, Zhong L, Huang Y, Dong MQ, Walker CL, Hogan PG, Wang Y, Zhou Y. Proteomic mapping of ER-PM junctions identifies STIMATE as a regulator of Ca²⁺ influx. Nat Cell Biol 2015; 17:1339-47. [PMID: 26322679 PMCID: PMC4589512 DOI: 10.1038/ncb3234] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 07/29/2015] [Indexed: 12/19/2022]
Abstract
Specialized junctional sites that connect the plasma membrane (PM) and endoplasmic reticulum (ER) play critical roles in controlling lipid metabolism and Ca2+ signaling1–4. Store operated Ca2+ entry mediated by dynamic STIM1-ORAI1 coupling represents a classical molecular event occurring at ER-PM junctions, but the protein composition and how previously-unrecognized protein regulators facilitate this process remain ill-defined. Using a combination of spatially-restricted biotin-labelling in situ coupled with mass spectrometry5, 6 and a secondary screen based on bimolecular fluorescence complementation7, we mapped the proteome of intact ER-PM junctions in living cells without disrupting their architectural integrity. Our approaches lead to the discovery of an ER-resident multi-transmembrane protein that we call STIMATE (STIM-activating enhancer, encoded by TMEM110) as a positive regulator of Ca2+ influx in vertebrates. STIMATE physically interacts with STIM1 to promote STIM1 conformational switch. Genetic depletion of STIMATE substantially reduces STIM1 puncta formation at ER-PM junctions and suppresses the Ca2+-NFAT signaling. Our findings enable further genetic studies to elucidate the function of STIMATE in normal physiology and disease, and set the stage to uncover more uncharted functions of hitherto underexplored ER-PM junctions.
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Affiliation(s)
- Ji Jing
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Lian He
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Aomin Sun
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Ariel Quintana
- Division of Signaling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
| | - Yuehe Ding
- National Institute of Biological Sciences, Beijing 102206, China
| | - Guolin Ma
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Peng Tan
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Xiaowen Liang
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Xiaolu Zheng
- Institute of Molecular Medicine, Peking University, Beijing 100871, China
| | - Liangyi Chen
- Institute of Molecular Medicine, Peking University, Beijing 100871, China
| | - Xiaodong Shi
- Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, USA
| | - Shenyuan L Zhang
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas 76504, USA
| | - Ling Zhong
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Yun Huang
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing 102206, China
| | - Cheryl L Walker
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Patrick G Hogan
- Division of Signaling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
| | - Youjun Wang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Yubin Zhou
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA.,Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas 76504, USA
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116
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Robinson A, McDonald JP, Caldas VEA, Patel M, Wood EA, Punter CM, Ghodke H, Cox MM, Woodgate R, Goodman MF, van Oijen AM. Regulation of Mutagenic DNA Polymerase V Activation in Space and Time. PLoS Genet 2015; 11:e1005482. [PMID: 26317348 PMCID: PMC4552617 DOI: 10.1371/journal.pgen.1005482] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 08/03/2015] [Indexed: 01/04/2023] Open
Abstract
Spatial regulation is often encountered as a component of multi-tiered regulatory systems in eukaryotes, where processes are readily segregated by organelle boundaries. Well-characterized examples of spatial regulation are less common in bacteria. Low-fidelity DNA polymerase V (UmuD′2C) is produced in Escherichia coli as part of the bacterial SOS response to DNA damage. Due to the mutagenic potential of this enzyme, pol V activity is controlled by means of an elaborate regulatory system at transcriptional and posttranslational levels. Using single-molecule fluorescence microscopy to visualize UmuC inside living cells in space and time, we now show that pol V is also subject to a novel form of spatial regulation. After an initial delay (~ 45 min) post UV irradiation, UmuC is synthesized, but is not immediately activated. Instead, it is sequestered at the inner cell membrane. The release of UmuC into the cytosol requires the RecA* nucleoprotein filament-mediated cleavage of UmuD→UmuD′. Classic SOS damage response mutants either block [umuD(K97A)] or constitutively stimulate [recA(E38K)] UmuC release from the membrane. Foci of mutagenically active pol V Mut (UmuD′2C-RecA-ATP) formed in the cytosol after UV irradiation do not co-localize with pol III replisomes, suggesting a capacity to promote translesion DNA synthesis at lesions skipped over by DNA polymerase III. In effect, at least three molecular mechanisms limit the amount of time that pol V has to access DNA: (1) transcriptional and posttranslational regulation that initially keep the intracellular levels of pol V to a minimum; (2) spatial regulation via transient sequestration of UmuC at the membrane, which further delays pol V activation; and (3) the hydrolytic activity of a recently discovered pol V Mut ATPase function that limits active polymerase time on the chromosomal template. Escherichia coli, and many other bacteria, respond to high levels of DNA damage with an inducible system called the SOS response. In this response, bacteria first try to restart replication using non-mutagenic DNA repair strategies. If that fails, replication can be restored using DNA polymerases that simply replicate over DNA lesions, a desperation strategy that results in mutations. DNA polymerase V (pol V) is responsible for most mutagenesis that accompanies the SOS response. Because of the risk inherent to elevated mutation levels, pol V activation is tightly constrained. This report introduces a new layer of regulation on pol V activation, with a novel spatial component. After synthesis, the UmuC subunit of pol V is sequestered transiently at the membrane. Release into the cytosol and final activation depends on the activity of RecA protein and the autocatalytic cleavage of UmuD to generate the UmuD' subunit of pol V. The resulting delay in activation represents an additional molecular mechanism that limits the amount of time that this sometimes necessary but potentially detrimental enzyme spends on the DNA.
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Affiliation(s)
- Andrew Robinson
- Zernike Institute for Advanced Materials, Centre for Synthetic Biology, University of Groningen, Groningen, The Netherlands
- * E-mail:
| | - John P. McDonald
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Victor E. A. Caldas
- Zernike Institute for Advanced Materials, Centre for Synthetic Biology, University of Groningen, Groningen, The Netherlands
| | - Meghna Patel
- Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, California, United States of America
| | - Elizabeth A. Wood
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Christiaan M. Punter
- Zernike Institute for Advanced Materials, Centre for Synthetic Biology, University of Groningen, Groningen, The Netherlands
| | - Harshad Ghodke
- Zernike Institute for Advanced Materials, Centre for Synthetic Biology, University of Groningen, Groningen, The Netherlands
| | - Michael M. Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Roger Woodgate
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Myron F. Goodman
- Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, California, United States of America
| | - Antoine M. van Oijen
- Zernike Institute for Advanced Materials, Centre for Synthetic Biology, University of Groningen, Groningen, The Netherlands
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Chung J, Torta F, Masai K, Lucast L, Czapla H, Tanner LB, Narayanaswamy P, Wenk MR, Nakatsu F, De Camilli P. INTRACELLULAR TRANSPORT. PI4P/phosphatidylserine countertransport at ORP5- and ORP8-mediated ER-plasma membrane contacts. Science 2015. [PMID: 26206935 DOI: 10.1126/science.aab1370] [Citation(s) in RCA: 607] [Impact Index Per Article: 67.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Lipid transfer between cell membrane bilayers at contacts between the endoplasmic reticulum (ER) and other membranes help to maintain membrane lipid homeostasis. We found that two similar ER integral membrane proteins, oxysterol-binding protein (OSBP)-related protein 5 (ORP5) and ORP8, tethered the ER to the plasma membrane (PM) via the interaction of their pleckstrin homology domains with phosphatidylinositol 4-phosphate (PI4P) in this membrane. Their OSBP-related domains (ORDs) harbored either PI4P or phosphatidylserine (PS) and exchanged these lipids between bilayers. Gain- and loss-of-function experiments showed that ORP5 and ORP8 could mediate PI4P/PS countertransport between the ER and the PM, thus delivering PI4P to the ER-localized PI4P phosphatase Sac1 for degradation and PS from the ER to the PM. This exchange helps to control plasma membrane PI4P levels and selectively enrich PS in the PM.
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Affiliation(s)
- Jeeyun Chung
- Department of Cell Biology, Howard Hughes Medical Institute, Kavli Institute for Neuroscience, and Program for Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06520, USA
| | - Federico Torta
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 117456 Singapore
| | - Kaori Masai
- Department of Cell Biology, Howard Hughes Medical Institute, Kavli Institute for Neuroscience, and Program for Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06520, USA
| | - Louise Lucast
- Department of Cell Biology, Howard Hughes Medical Institute, Kavli Institute for Neuroscience, and Program for Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06520, USA
| | - Heather Czapla
- Department of Cell Biology, Howard Hughes Medical Institute, Kavli Institute for Neuroscience, and Program for Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06520, USA
| | - Lukas B Tanner
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 117456 Singapore
| | - Pradeep Narayanaswamy
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 117456 Singapore
| | - Markus R Wenk
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 117456 Singapore
| | - Fubito Nakatsu
- Department of Cell Biology, Howard Hughes Medical Institute, Kavli Institute for Neuroscience, and Program for Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06520, USA.
| | - Pietro De Camilli
- Department of Cell Biology, Howard Hughes Medical Institute, Kavli Institute for Neuroscience, and Program for Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06520, USA.
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118
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Ungermann C. vCLAMPs—an intimate link between vacuoles and mitochondria. Curr Opin Cell Biol 2015; 35:30-6. [DOI: 10.1016/j.ceb.2015.03.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/20/2015] [Accepted: 03/26/2015] [Indexed: 11/26/2022]
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119
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Henne WM, Liou J, Emr SD. Molecular mechanisms of inter-organelle ER–PM contact sites. Curr Opin Cell Biol 2015; 35:123-30. [DOI: 10.1016/j.ceb.2015.05.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 04/23/2015] [Accepted: 05/01/2015] [Indexed: 10/23/2022]
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120
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Abstract
Lysosomes provide a major source for cellular cholesterol; however, most of this cholesterol is trafficked to the plasma membrane via unknown mechanisms. Chu et al. identify an unexpected role for peroxisomes in the transport of cholesterol from the lysosome to the plasma membrane via a lysosome-peroxisome membrane contact site.
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Affiliation(s)
- Yui Jin
- Department of Cell and Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Bethany S Strunk
- Department of Cell and Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Lois S Weisman
- Department of Cell and Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA.
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121
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Kentala H, Pfisterer SG, Olkkonen VM, Weber-Boyvat M. Sterol liganding of OSBP-related proteins (ORPs) regulates the subcellular distribution of ORP-VAPA complexes and their impacts on organelle structure. Steroids 2015; 99:248-58. [PMID: 25681634 DOI: 10.1016/j.steroids.2015.01.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 01/21/2015] [Accepted: 01/22/2015] [Indexed: 01/20/2023]
Abstract
Oxysterol-binding protein (OSBP) and its homologues (ORPs) are lipid-binding/transfer proteins with affinity for oxysterols, cholesterol and glycerophospholipids. In addition to a ligand-binding domain, a majority of the ORPs carry a pleckstrin homology domain that targets organelle membranes via phosphoinositides, and a motif targeting the endoplasmic reticulum (ER) via VAMP-associated proteins (VAPs). We employed here Bimolecular Fluorescence Complementation (BiFC) to systematically assess the effects of sterol manipulation of HuH7 cells on complexes of established sterol-binding ORPs with their ER receptor, VAMP-associated protein A (VAPA). Depletion of cellular cholesterol with lipoprotein-deficient medium and Mevastatin caused concentration of OSBP-VAPA complexes and Golgi complex markers at a juxtanuclear position, an effect reversed by low-density lipoprotein treatment. A similar redistribution of OSBP-VAPA but not of sterol-binding deficient mutant OSBP(ΔELSK)-VAPA, occurred upon treatment with the high-affinity ligand, 25-hydroxycholesterol (25OHC), which reduced total and free cholesterol. ORP2-VAPA complexes, which localize in untreated cells at blob-like ER structures with associated lipid droplets, were redistributed upon treatment with the ORP2 ligand 22(R)OHC to a diffuse cytoplasmic/ER pattern and the plasma membrane. Analogously, distribution of ORP4L-VAPA complexes between the plasma membrane and vimentin intermediate filament associated compartments was modified by statin or 25OHC treatment. The treatments resulted in loss of vimentin co-localization, and sterol-binding deficient ORP4L(ΔELSR)-VAPA localized predominantly to the plasma membrane. In conclusion, treatment with statin or oxysterol ligands modify the subcellular targeting of ORP-VAPA complexes, consistent with the notion that this machinery controls lipid homeostasis and signaling at organelle interfaces.
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Affiliation(s)
- Henriikka Kentala
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, FI-00290 Helsinki, Finland
| | - Simon G Pfisterer
- Institute of Biomedicine, Anatomy, FI-00014 University of Helsinki, Finland
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, FI-00290 Helsinki, Finland; Institute of Biomedicine, Anatomy, FI-00014 University of Helsinki, Finland
| | - Marion Weber-Boyvat
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, FI-00290 Helsinki, Finland.
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122
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Elbaz-Alon Y, Eisenberg-Bord M, Shinder V, Stiller SB, Shimoni E, Wiedemann N, Geiger T, Schuldiner M. Lam6 Regulates the Extent of Contacts between Organelles. Cell Rep 2015; 12:7-14. [PMID: 26119743 PMCID: PMC4518459 DOI: 10.1016/j.celrep.2015.06.022] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/10/2015] [Accepted: 06/08/2015] [Indexed: 11/16/2022] Open
Abstract
Communication between organelles is crucial for eukaryotic cells to function as one coherent unit. An important means of communication is through membrane contact sites, where two organelles come into close proximity allowing the transport of lipids and small solutes between them. Contact sites are dynamic in size and can change in response to environmental or cellular stimuli; however, how this is regulated has been unclear. Here, we show that Saccharomyces cerevisiae Lam6 resides in several central contact sites: ERMES (ER/mitochondria encounter structure), vCLAMP (vacuole and mitochondria patch), and NVJ (nuclear vacuolar junction). We show that Lam6 is sufficient for expansion of contact sites under physiological conditions and necessary for coordination of contact site size. Given that Lam6 is part of a large protein family and is conserved in vertebrates, our work opens avenues for investigating the underlying principles of organelle communication. Lam6 is localized to three major cellular contacts: ERMES, vCLAMP, and NVJ Lam6 is a GRAM domain protein conserved from yeast to humans Overexpression of Lam6 results in the expansion of all three contact sites Lam6 is essential for the cross-talk between ERMES and vCLAMP
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Affiliation(s)
- Yael Elbaz-Alon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michal Eisenberg-Bord
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Vera Shinder
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sebastian Berthold Stiller
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung (ZBMZ), Universität Freiburg, Freiburg 79104, Germany; Fakultät für Biologie, Universität Freiburg, Freiburg 79104, Germany
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nils Wiedemann
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung (ZBMZ), Universität Freiburg, Freiburg 79104, Germany; BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg 79104, Germany
| | - Tamar Geiger
- Department of Human Molecular Genetics and Biochemistry, Tel-Aviv University, Tel Aviv 6997801, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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123
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Conserved SMP domains of the ERMES complex bind phospholipids and mediate tether assembly. Proc Natl Acad Sci U S A 2015; 112:E3179-88. [PMID: 26056272 DOI: 10.1073/pnas.1422363112] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Membrane contact sites (MCS) between organelles are proposed as nexuses for the exchange of lipids, small molecules, and other signals crucial to cellular function and homeostasis. Various protein complexes, such as the endoplasmic reticulum-mitochondrial encounter structure (ERMES), function as dynamic molecular tethers between organelles. Here, we report the reconstitution and characterization of subcomplexes formed by the cytoplasm-exposed synaptotagmin-like mitochondrial lipid-binding protein (SMP) domains present in three of the five ERMES subunits--the soluble protein Mdm12, the endoplasmic reticulum (ER)-resident membrane protein Mmm1, and the mitochondrial membrane protein Mdm34. SMP domains are conserved lipid-binding domains found exclusively in proteins at MCS. We show that the SMP domains of Mdm12 and Mmm1 associate into a tight heterotetramer with equimolecular stoichiometry. Our 17-Å-resolution EM structure of the complex reveals an elongated crescent-shaped particle in which two Mdm12 subunits occupy symmetric but distal positions at the opposite ends of a central ER-anchored Mmm1 homodimer. Rigid body fitting of homology models of these SMP domains in the density maps reveals a distinctive extended tubular structure likely traversed by a hydrophobic tunnel. Furthermore, these two SMP domains bind phospholipids and display a strong preference for phosphatidylcholines, a class of phospholipids whose exchange between the ER and mitochondria is essential. Last, we show that the three SMP-containing ERMES subunits form a ternary complex in which Mdm12 bridges Mmm1 to Mdm34. Our findings highlight roles for SMP domains in ERMES assembly and phospholipid binding and suggest a structure-based mechanism for the facilitated transport of phospholipids between organelles.
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124
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Li Y, Xin H, Liu X, Li B. Non-contact intracellular binding of chloroplasts in vivo. Sci Rep 2015; 5:10925. [PMID: 26043396 PMCID: PMC4455249 DOI: 10.1038/srep10925] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 05/08/2015] [Indexed: 12/12/2022] Open
Abstract
Non-contact intracellular binding and controllable manipulation of chloroplasts in vivo was demonstrated using an optical fiber probe. Launching a 980-nm laser beam into a fiber, which was placed about 3 μm above the surface of a living plant (Hydrilla verticillata) leaf, enabled stable binding of different numbers of chloroplasts, as well as their arrangement into one-dimensional chains and two-dimensional arrays inside the leaf without damaging the chloroplasts. Additionally, the formed chloroplast chains were controllably transported inside the living cells. The optical force exerted on the chloroplasts was calculated to explain the experimental results. This method provides a flexible method for studying intracellular organelle interaction with highly organized organelle-organelle contact in vivo in a non-contact manner.
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Affiliation(s)
- Yuchao Li
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Hongbao Xin
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Xiaoshuai Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | - Baojun Li
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
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125
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Raiborg C, Wenzel EM, Stenmark H. ER-endosome contact sites: molecular compositions and functions. EMBO J 2015; 34:1848-58. [PMID: 26041457 DOI: 10.15252/embj.201591481] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 03/31/2015] [Indexed: 01/05/2023] Open
Abstract
Recent studies have revealed the existence of numerous contact sites between the endoplasmic reticulum (ER) and endosomes in mammalian cells. Such contacts increase during endosome maturation and play key roles in cholesterol transfer, endosome positioning, receptor dephosphorylation, and endosome fission. At least 7 distinct contact sites between the ER and endosomes have been identified to date, which have diverse molecular compositions. Common to these contact sites is that they impose a close apposition between the ER and endosome membranes, which excludes membrane fusion while allowing the flow of molecular signals between the two membranes, in the form of enzymatic modifications, or ion, lipid, or protein transfer. Thus, ER-endosome contact sites ensure coordination of molecular activities between the two compartments while keeping their general compositions intact. Here, we review the molecular architectures and cellular functions of known ER-endosome contact sites and discuss their implications for human health.
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Affiliation(s)
- Camilla Raiborg
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway Department of Molecular Cell Biology, Institute for Cancer Research Oslo University Hospital, Oslo, Norway
| | - Eva M Wenzel
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway Department of Molecular Cell Biology, Institute for Cancer Research Oslo University Hospital, Oslo, Norway
| | - Harald Stenmark
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway Department of Molecular Cell Biology, Institute for Cancer Research Oslo University Hospital, Oslo, Norway Centre of Molecular Inflammation Research, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
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126
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Liang J, Kulasiri D, Samarasinghe S. Ca2+ dysregulation in the endoplasmic reticulum related to Alzheimer's disease: A review on experimental progress and computational modeling. Biosystems 2015; 134:1-15. [PMID: 25998697 DOI: 10.1016/j.biosystems.2015.05.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 05/12/2015] [Accepted: 05/12/2015] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is a devastating, incurable neurodegenerative disease affecting millions of people worldwide. Dysregulation of intracellular Ca(2+) signaling has been observed as an early event prior to the presence of clinical symptoms of AD and is believed to be a crucial factor contributing to its pathogenesis. The progressive and sustaining increase in the resting level of cytosolic Ca(2+) will affect downstream activities and neural functions. This review focuses on the issues relating to the increasing Ca(2+) release from the endoplasmic reticulum (ER) observed in AD neurons. Numerous research papers have suggested that the dysregulation of ER Ca(2+) homeostasis is associated with mutations in the presenilin genes and amyloid-β oligomers. These disturbances could happen at many different points in the signaling process, directly affecting ER Ca(2+) channels or interfering with related pathways, which makes it harder to reveal the underlying mechanisms. This review paper also shows that computational modeling is a powerful tool in Ca(2+) signaling studies and discusses the progress in modeling related to Ca(2+) dysregulation in AD research.
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Affiliation(s)
- Jingyi Liang
- Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Christchurch, New Zealand; Department of Molecular Biosciences, Lincoln University, Christchurch, New Zealand
| | - Don Kulasiri
- Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Christchurch, New Zealand; Department of Molecular Biosciences, Lincoln University, Christchurch, New Zealand.
| | - Sandhya Samarasinghe
- Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Christchurch, New Zealand; Department of Informatics and Enabling Technologies, Lincoln University, Christchurch, New Zealand
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127
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De Matteis MA, Rega LR. Endoplasmic reticulum-Golgi complex membrane contact sites. Curr Opin Cell Biol 2015; 35:43-50. [PMID: 25950841 DOI: 10.1016/j.ceb.2015.04.001] [Citation(s) in RCA: 203] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/10/2015] [Accepted: 04/11/2015] [Indexed: 11/24/2022]
Abstract
Although they were identified as long ago as the 1960s, there are still many unknowns regarding the functions and composition of membrane contact sites between the endoplasmic reticulum (ER) and the trans-Golgi (TG). While it seems to be fairly well established that they facilitate lipid exchange between the two organelles, much less is known about how they are regulated. A bottleneck in the study of the ER-TG contact sites has been the absence of methods for their biochemical isolation and visualization by light microscopy. Herein we provide an overview of current knowledge about ER-TG contact sites with a particular emphasis on the questions that remain to be explored.
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Affiliation(s)
| | - Laura Rita Rega
- Division of Nephrology and Dialysis, Bambino Gesù Children's Hospital - Scientific Institute, Piazza Sant'Onofrio, 4, 00165 Rome, Italy
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128
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Weber-Boyvat M, Kentala H, Peränen J, Olkkonen VM. Ligand-dependent localization and function of ORP-VAP complexes at membrane contact sites. Cell Mol Life Sci 2015; 72:1967-87. [PMID: 25420878 PMCID: PMC11114005 DOI: 10.1007/s00018-014-1786-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 10/17/2014] [Accepted: 11/17/2014] [Indexed: 01/08/2023]
Abstract
Oxysterol-binding protein/OSBP-related proteins (ORPs) constitute a conserved family of sterol/phospholipid-binding proteins with lipid transporter or sensor functions. We investigated the spatial occurrence and regulation of the interactions of human OSBP/ORPs or the S. cerevisiae orthologs, the Osh (OSBP homolog) proteins, with their endoplasmic reticulum (ER) anchors, the VAMP-associated proteins (VAPs), by employing bimolecular fluorescence complementation and pull-down set-ups. The ORP-VAP interactions localize frequently at distinct subcellular sites, shown in several cases to represent membrane contact sites (MCSs). Using established ORP ligand-binding domain mutants and pull-down assays with recombinant proteins, we show that ORP liganding regulates the ORP-VAP association, alters the subcellular targeting of ORP-VAP complexes, or modifies organelle morphology. There is distinct protein specificity in the effects of the mutants on subcellular targeting of ORP-VAP complexes. We provide evidence that complexes of human ORP2 and VAPs at ER-lipid droplet interfaces regulate the hydrolysis of triglycerides and lipid droplet turnover. The data suggest evolutionarily conserved, complex ligand-dependent functions of ORP-VAP complexes at MCSs, with implications for cellular lipid homeostasis and signaling.
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Affiliation(s)
- Marion Weber-Boyvat
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Tukholmankatu 8, 00290 Helsinki, Finland
| | - Henriikka Kentala
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Tukholmankatu 8, 00290 Helsinki, Finland
| | - Johan Peränen
- Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Vesa M. Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Tukholmankatu 8, 00290 Helsinki, Finland
- Institute of Biomedicine, Anatomy, University of Helsinki, 00014 Helsinki, Finland
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129
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Rowland AA, Chitwood PJ, Phillips MJ, Voeltz GK. ER contact sites define the position and timing of endosome fission. Cell 2015; 159:1027-1041. [PMID: 25416943 DOI: 10.1016/j.cell.2014.10.023] [Citation(s) in RCA: 296] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/13/2014] [Accepted: 09/24/2014] [Indexed: 10/24/2022]
Abstract
Endocytic cargo and Rab GTPases are segregated to distinct domains of an endosome. These domains maintain their identity until they undergo fission to traffic cargo. It is not fully understood how segregation of cargo or Rab proteins is maintained along the continuous endosomal membrane or what machinery is required for fission. Endosomes form contact sites with the endoplasmic reticulum (ER) that are maintained during trafficking. Here, we show that stable contacts form between the ER and endosome at constricted sorting domains, and free diffusion of cargo is limited at these positions. We demonstrate that the site of constriction and fission for early and late endosomes is spatially and temporally linked to contact sites with the ER. Lastly, we show that altering ER structure and dynamics reduces the efficiency of endosome fission. Together, these data reveal a surprising role for ER contact in defining the timing and position of endosome fission.
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Affiliation(s)
- Ashley A Rowland
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Patrick J Chitwood
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Melissa J Phillips
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Gia K Voeltz
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
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130
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Suresh HG, da Silveira Dos Santos AX, Kukulski W, Tyedmers J, Riezman H, Bukau B, Mogk A. Prolonged starvation drives reversible sequestration of lipid biosynthetic enzymes and organelle reorganization in Saccharomyces cerevisiae. Mol Biol Cell 2015; 26:1601-15. [PMID: 25761633 PMCID: PMC4436773 DOI: 10.1091/mbc.e14-11-1559] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 03/02/2015] [Indexed: 11/11/2022] Open
Abstract
Lipid homeostasis is modulated upon starvation at three different levels manifested in reversible 1) spatial confinement of lipid biosynthetic enzymes, 2) mitochondrial and endoplasmic reticular reorganization, and 3) loss of organelle contact sites, thus highlighting a novel mechanism regulating lipid biosynthesis by simply modulating flux through the pathway. Cells adapt to changing nutrient availability by modulating a variety of processes, including the spatial sequestration of enzymes, the physiological significance of which remains controversial. These enzyme deposits are claimed to represent aggregates of misfolded proteins, protein storage, or complexes with superior enzymatic activity. We monitored spatial distribution of lipid biosynthetic enzymes upon glucose depletion in Saccharomyces cerevisiae. Several different cytosolic-, endoplasmic reticulum–, and mitochondria-localized lipid biosynthetic enzymes sequester into distinct foci. Using the key enzyme fatty acid synthetase (FAS) as a model, we show that FAS foci represent active enzyme assemblies. Upon starvation, phospholipid synthesis remains active, although with some alterations, implying that other foci-forming lipid biosynthetic enzymes might retain activity as well. Thus sequestration may restrict enzymes' access to one another and their substrates, modulating metabolic flux. Enzyme sequestrations coincide with reversible drastic mitochondrial reorganization and concomitant loss of endoplasmic reticulum–mitochondria encounter structures and vacuole and mitochondria patch organelle contact sites that are reflected in qualitative and quantitative changes in phospholipid profiles. This highlights a novel mechanism that regulates lipid homeostasis without profoundly affecting the activity status of involved enzymes such that, upon entry into favorable growth conditions, cells can quickly alter lipid flux by relocalizing their enzymes.
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Affiliation(s)
- Harsha Garadi Suresh
- Center for Molecular Biology of the University of Heidelberg (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, D-69120 Heidelberg, Germany
| | | | - Wanda Kukulski
- Structural and Computational Biology Unit and Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany Structural and Computational Biology Unit and Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany
| | - Jens Tyedmers
- Department of Medicine I and Clinical Chemistry, University of Heidelberg, D-69120 Heidelberg, Germany
| | - Howard Riezman
- NCCR Chemical Biology, Department of Biochemistry, University of Geneva, CH-1211 Geneva, Switzerland
| | - Bernd Bukau
- Center for Molecular Biology of the University of Heidelberg (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, D-69120 Heidelberg, Germany
| | - Axel Mogk
- Center for Molecular Biology of the University of Heidelberg (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, D-69120 Heidelberg, Germany
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131
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Schuldiner M, Zalckvar E. Peroxisystem: Harnessing systems cell biology to study peroxisomes. Biol Cell 2015; 107:89-97. [DOI: 10.1111/boc.201400091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/05/2015] [Indexed: 12/14/2022]
Affiliation(s)
- Maya Schuldiner
- Department of Molecular Genetics; Weizmann Institute of Science; Rehovot 7610001 Israel
| | - Einat Zalckvar
- Department of Molecular Genetics; Weizmann Institute of Science; Rehovot 7610001 Israel
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132
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Burgoyne T, Patel S, Eden ER. Calcium signaling at ER membrane contact sites. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:2012-7. [PMID: 25662816 DOI: 10.1016/j.bbamcr.2015.01.022] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 01/26/2015] [Accepted: 01/28/2015] [Indexed: 11/27/2022]
Abstract
Communication between organelles is a necessary consequence of intracellular compartmentalization. Membrane contact sites (MCSs) are regions where the membranes of two organelles come into close apposition allowing exchange of small molecules and ions including Ca²⁺. The ER, the cell's major Ca²⁺ store, forms an extensive and dynamic network of contacts with multiple organelles. Here we review established and emerging roles of ER contacts as platforms for Ca²⁺ exchange and further consider a potential role for Ca²⁺ in the regulation of MCS formation. We additionally discuss the challenges associated with the study of MCS biology and highlight advances in microscopy-based solutions. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.
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Affiliation(s)
| | - Sandip Patel
- Department of Cell and Developmental Biology, UCL, London, UK
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133
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Jin K, Musso G, Vlasblom J, Jessulat M, Deineko V, Negroni J, Mosca R, Malty R, Nguyen-Tran DH, Aoki H, Minic Z, Freywald T, Phanse S, Xiang Q, Freywald A, Aloy P, Zhang Z, Babu M. Yeast Mitochondrial Protein–Protein Interactions Reveal Diverse Complexes and Disease-Relevant Functional Relationships. J Proteome Res 2015; 14:1220-37. [DOI: 10.1021/pr501148q] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Ke Jin
- Terrence
Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Gabriel Musso
- Cardiovascular
Division, Brigham and Women’s Hospital, Boston, Massachusetts 02115, United States
- Department
of Medicine, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - James Vlasblom
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Matthew Jessulat
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Viktor Deineko
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Jacopo Negroni
- Joint
IRB−BSC Program in Computational Biology, IRB, Barcelona 08028, Spain
| | - Roberto Mosca
- Joint
IRB−BSC Program in Computational Biology, IRB, Barcelona 08028, Spain
| | - Ramy Malty
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Diem-Hang Nguyen-Tran
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Hiroyuki Aoki
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Zoran Minic
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Tanya Freywald
- Cancer Research
Unit, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Sadhna Phanse
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Qian Xiang
- Terrence
Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Andrew Freywald
- Cancer Research
Unit, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Patrick Aloy
- Joint
IRB−BSC Program in Computational Biology, IRB, Barcelona 08028, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain
| | - Zhaolei Zhang
- Terrence
Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Mohan Babu
- Department
of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
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134
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Kralt A, Carretta M, Mari M, Reggiori F, Steen A, Poolman B, Veenhoff LM. Intrinsically Disordered Linker and Plasma Membrane-Binding Motif Sort Ist2 and Ssy1 to Junctions. Traffic 2014; 16:135-47. [DOI: 10.1111/tra.12243] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 11/17/2014] [Accepted: 11/18/2014] [Indexed: 12/25/2022]
Affiliation(s)
- Annemarie Kralt
- European Institute for the Biology of Ageing (ERIBA); University of Groningen, University Medical Center Groningen, Netherlands Proteomics Centre; Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Marco Carretta
- European Institute for the Biology of Ageing (ERIBA); University of Groningen, University Medical Center Groningen, Netherlands Proteomics Centre; Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
- Current address: Department of Hematology, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - Muriel Mari
- Department of Cell Biology; Center for Molecular Medicine, University Medical Center Utrecht; Heidelberglaan 100 3584 CX Utrecht The Netherlands
| | - Fulvio Reggiori
- Department of Cell Biology; Center for Molecular Medicine, University Medical Center Utrecht; Heidelberglaan 100 3584 CX Utrecht The Netherlands
| | - Anton Steen
- European Institute for the Biology of Ageing (ERIBA); University of Groningen, University Medical Center Groningen, Netherlands Proteomics Centre; Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Bert Poolman
- Department of Biochemistry; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Liesbeth M. Veenhoff
- European Institute for the Biology of Ageing (ERIBA); University of Groningen, University Medical Center Groningen, Netherlands Proteomics Centre; Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
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135
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A fungal sarcolemmal membrane-associated protein (SLMAP) homolog plays a fundamental role in development and localizes to the nuclear envelope, endoplasmic reticulum, and mitochondria. EUKARYOTIC CELL 2014; 14:345-58. [PMID: 25527523 DOI: 10.1128/ec.00241-14] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/13/2014] [Indexed: 11/20/2022]
Abstract
Sarcolemmal membrane-associated protein (SLMAP) is a tail-anchored protein involved in fundamental cellular processes, such as myoblast fusion, cell cycle progression, and chromosomal inheritance. Further, SLMAP misexpression is associated with endothelial dysfunctions in diabetes and cancer. SLMAP is part of the conserved striatin-interacting phosphatase and kinase (STRIPAK) complex required for specific signaling pathways in yeasts, filamentous fungi, insects, and mammals. In filamentous fungi, STRIPAK was initially discovered in Sordaria macrospora, a model system for fungal differentiation. Here, we functionally characterize the STRIPAK subunit PRO45, a homolog of human SLMAP. We show that PRO45 is required for sexual propagation and cell-to-cell fusion and that its forkhead-associated (FHA) domain is essential for these processes. Protein-protein interaction studies revealed that PRO45 binds to STRIPAK subunits PRO11 and SmMOB3, which are also required for sexual propagation. Superresolution structured-illumination microscopy (SIM) further established that PRO45 localizes to the nuclear envelope, endoplasmic reticulum, and mitochondria. SIM also showed that localization to the nuclear envelope requires STRIPAK subunits PRO11 and PRO22, whereas for mitochondria it does not. Taken together, our study provides important insights into fundamental roles of the fungal SLMAP homolog PRO45 and suggests STRIPAK-related and STRIPAK-unrelated functions.
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136
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Kalderon B, Pines O. Protein folding as a driving force for dual protein targeting in eukaryotes. Front Mol Biosci 2014; 1:23. [PMID: 25988164 PMCID: PMC4428415 DOI: 10.3389/fmolb.2014.00023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 10/28/2014] [Indexed: 01/19/2023] Open
Abstract
It is well documented that in eukaryotic cells molecules of one protein can be located in several subcellular locations, a phenomenon termed dual targeting, dual localization, or dual distribution. The differently localized identical or nearly identical proteins are termed “echoforms.” Our conventional definition of dual targeted proteins refers to situations in which one of the echoforms is translocated through/into a membrane. Thus, dual targeted proteins are recognized by at least one organelle's receptors and translocation machineries within the lipid bilayer. In this review we attempt to evaluate mechanisms and situations in which protein folding is the major determinant of dual targeting and of the relative distribution levels of echoforms in the subcellular compartments of the eukaryotic cell. We show that the decisive folding step can occur prior, during or after translocation through the bilayer of a biological membrane. This phenomenon involves folding catalysts in the cell such as chaperones, proteases and modification enzymes, and targeting processes such as signal recognition, translocation through membranes, trapping, retrotranslocation and reverse translocation.
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Affiliation(s)
- Bella Kalderon
- Department of Microbiology and Molecular Genetics, Faculty of Medicine, Institute for Medical Research Israel-Canada, Hebrew University of Jerusalem Jerusalem, Israel
| | - Ophry Pines
- Department of Microbiology and Molecular Genetics, Faculty of Medicine, Institute for Medical Research Israel-Canada, Hebrew University of Jerusalem Jerusalem, Israel ; CREATE-NUS-HUJ Cellular and Molecular Mechanisms of Inflammation Program, National University of Singapore Singapore, Singapore
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137
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Hooper SL, Burstein HJ. Minimization of extracellular space as a driving force in prokaryote association and the origin of eukaryotes. Biol Direct 2014; 9:24. [PMID: 25406691 PMCID: PMC4289276 DOI: 10.1186/1745-6150-9-24] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 11/03/2014] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Internalization-based hypotheses of eukaryotic origin require close physical association of host and symbiont. Prior hypotheses of how these associations arose include chance, specific metabolic couplings between partners, and prey-predator/parasite interactions. Since these hypotheses were proposed, it has become apparent that mixed-species, close-association assemblages (biofilms) are widespread and predominant components of prokaryotic ecology. Which forces drove prokaryotes to evolve the ability to form these assemblages are uncertain. Bacteria and archaea have also been found to form membrane-lined interconnections (nanotubes) through which proteins and RNA pass. These observations, combined with the structure of the nuclear envelope and an energetic benefit of close association (see below), lead us to propose a novel hypothesis of the driving force underlying prokaryotic close association and the origin of eukaryotes. RESULTS Respiratory proton transport does not alter external pH when external volume is effectively infinite. Close physical association decreases external volume. For small external volumes, proton transport decreases external pH, resulting in each transported proton increasing proton motor force to a greater extent. We calculate here that in biofilms this effect could substantially decrease how many protons need to be transported to achieve a given proton motor force. Based as it is solely on geometry, this energetic benefit would occur for all prokaryotes using proton-based respiration. CONCLUSIONS This benefit may be a driving force in biofilm formation. Under this hypothesis a very wide range of prokaryotic species combinations could serve as eukaryotic progenitors. We use this observation and the discovery of prokaryotic nanotubes to propose that eukaryotes arose from physically distinct, functionally specialized (energy factory, protein factory, DNA repository/RNA factory), obligatorily symbiotic prokaryotes in which the protein factory and DNA repository/RNA factory cells were coupled by nanotubes and the protein factory ultimately internalized the other two. This hypothesis naturally explains many aspects of eukaryotic physiology, including the nuclear envelope being a folded single membrane repeatedly pierced by membrane-bound tubules (the nuclear pores), suggests that species analogous or homologous to eukaryotic progenitors are likely unculturable as monocultures, and makes a large number of testable predictions. REVIEWERS This article was reviewed by Purificación López-García and Toni Gabaldón.
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Affiliation(s)
- Scott L Hooper
- Department of Biological Sciences, Ohio University, Athens, OH 45701 USA
| | - Helaine J Burstein
- Department of Biological Sciences, Ohio University, Athens, OH 45701 USA
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138
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López Sanjurjo CI, Tovey SC, Taylor CW. Rapid recycling of Ca2+ between IP3-sensitive stores and lysosomes. PLoS One 2014; 9:e111275. [PMID: 25337829 PMCID: PMC4206489 DOI: 10.1371/journal.pone.0111275] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/28/2014] [Indexed: 11/26/2022] Open
Abstract
Inositol 1,4,5-trisphosphate (IP3) evokes release of Ca2+ from the endoplasmic reticulum (ER), but the resulting Ca2+ signals are shaped by interactions with additional intracellular organelles. Bafilomycin A1, which prevents lysosomal Ca2+ uptake by inhibiting H+ pumping into lysosomes, increased the amplitude of the initial Ca2+ signals evoked by carbachol in human embryonic kidney (HEK) cells. Carbachol alone and carbachol in combination with parathyroid hormone (PTH) evoke Ca2+ release from distinct IP3-sensitive Ca2+ stores in HEK cells stably expressing human type 1 PTH receptors. Bafilomycin A1 similarly exaggerated the Ca2+ signals evoked by carbachol or carbachol with PTH, indicating that Ca2+ released from distinct IP3-sensitive Ca2+ stores is sequestered by lysosomes. The Ca2+ signals resulting from store-operated Ca2+ entry, whether evoked by thapsigargin or carbachol, were unaffected by bafilomycin A1. Using Gd3+ (1 mM) to inhibit both Ca2+ entry and Ca2+ extrusion, HEK cells were repetitively stimulated with carbachol to assess the effectiveness of Ca2+ recycling to the ER after IP3-evoked Ca2+ release. Blocking lysosomal Ca2+ uptake with bafilomycin A1 increased the amplitude of each carbachol-evoked Ca2+ signal without affecting the rate of Ca2+ recycling to the ER. This suggests that Ca2+ accumulated by lysosomes is rapidly returned to the ER. We conclude that lysosomes rapidly, reversibly and selectively accumulate the Ca2+ released by IP3 receptors residing within distinct Ca2+ stores, but not the Ca2+ entering cells via receptor-regulated, store-operated Ca2+ entry pathways.
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Affiliation(s)
| | - Stephen C. Tovey
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Colin W. Taylor
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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139
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Lahiri S, Chao JT, Tavassoli S, Wong AKO, Choudhary V, Young BP, Loewen CJR, Prinz WA. A conserved endoplasmic reticulum membrane protein complex (EMC) facilitates phospholipid transfer from the ER to mitochondria. PLoS Biol 2014; 12:e1001969. [PMID: 25313861 PMCID: PMC4196738 DOI: 10.1371/journal.pbio.1001969] [Citation(s) in RCA: 247] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 09/03/2014] [Indexed: 11/24/2022] Open
Abstract
Tethering of the endoplasmic reticulum to mitochondria by a conserved endoplasmic reticulum complex is needed for the transfer of phospholipids between these organelles. Mitochondrial membrane biogenesis and lipid metabolism require phospholipid transfer from the endoplasmic reticulum (ER) to mitochondria. Transfer is thought to occur at regions of close contact of these organelles and to be nonvesicular, but the mechanism is not known. Here we used a novel genetic screen in S. cerevisiae to identify mutants with defects in lipid exchange between the ER and mitochondria. We show that a strain missing multiple components of the conserved ER membrane protein complex (EMC) has decreased phosphatidylserine (PS) transfer from the ER to mitochondria. Mitochondria from this strain have significantly reduced levels of PS and its derivative phosphatidylethanolamine (PE). Cells lacking EMC proteins and the ER–mitochondria tethering complex called ERMES (the ER–mitochondria encounter structure) are inviable, suggesting that the EMC also functions as a tether. These defects are corrected by expression of an engineered ER–mitochondrial tethering protein that artificially tethers the ER to mitochondria. EMC mutants have a significant reduction in the amount of ER tethered to mitochondria even though ERMES remained intact in these mutants, suggesting that the EMC performs an additional tethering function to ERMES. We find that all Emc proteins interact with the mitochondrial translocase of the outer membrane (TOM) complex protein Tom5 and this interaction is important for PS transfer and cell growth, suggesting that the EMC forms a tether by associating with the TOM complex. Together, our findings support that the EMC tethers ER to mitochondria, which is required for phospholipid synthesis and cell growth. Mitochondrial membrane biogenesis and lipid metabolism depend on the transfer of phospholipid from the endoplasmic reticulum to mitochondria. This transfer is thought to occur at regions where these organelles are in close contact, and, although the process is thought not to involve vesicles, the mechanism is not known. In this study, we found a complex of proteins in the endoplasmic reticulum that is required for the transfer of one phospholipid—phosphatidylserine—from the endoplasmic reticulum to mitochondria. Cells lacking this protein complex have nonfunctional mitochondria with an abnormal lipid composition. We show that the complex is required to maintain close contacts between the endoplasmic reticulum and mitochondria; the complex probably directly interacts with at least one protein on the surface of mitochondria. In addition, cells lacking this complex and a second previously identified tethering complex are not viable. Thus, our findings suggest that tethering of the endoplasmic reticulum and mitochondria is essential for cell growth, likely because it is necessary for lipid exchange between these organelles.
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Affiliation(s)
- Sujoy Lahiri
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jesse T Chao
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Shabnam Tavassoli
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Andrew K O Wong
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Vineet Choudhary
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Barry P Young
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher J R Loewen
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - William A Prinz
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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140
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Galione A. A primer of NAADP-mediated Ca(2+) signalling: From sea urchin eggs to mammalian cells. Cell Calcium 2014; 58:27-47. [PMID: 25449298 DOI: 10.1016/j.ceca.2014.09.010] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 09/28/2014] [Accepted: 09/29/2014] [Indexed: 02/04/2023]
Abstract
Since the discovery of the Ca(2+) mobilizing effects of the pyridine nucleotide metabolite, nicotinic acid adenine dinucleotide phosphate (NAADP), this molecule has been demonstrated to function as a Ca(2+) mobilizing intracellular messenger in a wide range of cell types. In this review, I will briefly summarize the distinct principles behind NAADP-mediated Ca(2+) signalling before going on to outline the role of this messenger in the physiology of specific cell types. Central to the discussion here is the finding that NAADP principally mobilizes Ca(2+) from acidic organelles such as lysosomes and it is this property that allows NAADP to play a unique role in intracellular Ca(2+) signalling. Lysosomes and related organelles are small Ca(2+) stores but importantly may also initiate a two-way dialogue with other Ca(2+) storage organelles to amplify Ca(2+) release, and may be strategically localized to influence localized Ca(2+) signalling microdomains. The study of NAADP signalling has created a new and fruitful focus on the lysosome and endolysosomal system as major players in calcium signalling and pathophysiology.
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Affiliation(s)
- Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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141
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Contreras-Ferrat A, Lavandero S, Jaimovich E, Klip A. Calcium signaling in insulin action on striated muscle. Cell Calcium 2014; 56:390-6. [PMID: 25224502 DOI: 10.1016/j.ceca.2014.08.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 08/24/2014] [Accepted: 08/26/2014] [Indexed: 02/07/2023]
Abstract
Striated muscles (skeletal and cardiac) are major physiological targets of insulin and this hormone triggers complex signaling pathways regulating cell growth and energy metabolism. Insulin increases glucose uptake into muscle cells by stimulating glucose transporter (GLUT4) translocation from intracellular compartments to the cell surface. The canonical insulin-triggered signaling cascade controlling this process is constituted by well-mapped tyrosine, lipid and serine/threonine phosphorylation reactions. In parallel to these signals, recent findings reveal insulin-dependent Ca(2+) mobilization in skeletal muscle cells and cardiomyocytes. Specifically, insulin activates the sarco-endoplasmic reticulum (SER) channels that release Ca(2+) into the cytosol i.e., the Ryanodine Receptor (RyR) and the inositol 1,4,5-triphosphate receptor (IP3R). In skeletal muscle cells, a rapid, insulin-triggered Ca(2+) release occurs through RyR, that is brought about upon S-glutathionylation of cysteine residues in the channel by reactive oxygen species (ROS) produced by the early activation of the NADPH oxidase (NOX2). In cardiomyocytes insulin induces a fast and transient increase in cytoplasmic [Ca(2+)]i trough L-type Ca(2+) channels activation. In both cell types, a relatively slower Ca(2+) release also occurs through IP3R activation, and is required for GLUT4 translocation and glucose uptake. The insulin-dependent Ca(2+) released from IP3R of skeletal muscle also promotes mitochondrial Ca(2+) uptake. We review here these actions of insulin on intracellular Ca(2+) channel activation and their impact on GLUT4 traffic in muscle cells, as well as other implications of insulin-dependent Ca(2+) release from the SER.
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Affiliation(s)
- A Contreras-Ferrat
- Center for Molecular Studies of the Cell (CEMC), Faculty of Medicine, Chile; Advanced Center for Chronic Disease (ACCDiS), Faculty of Chemical and Pharmaceutical Sciences & Faculty of Medicine, Chile; Institute for Research in Dental Sciences, Faculty of Dentistry, University of Chile, Santiago 8380492, Chile.
| | - S Lavandero
- Center for Molecular Studies of the Cell (CEMC), Faculty of Medicine, Chile; Advanced Center for Chronic Disease (ACCDiS), Faculty of Chemical and Pharmaceutical Sciences & Faculty of Medicine, Chile
| | - E Jaimovich
- Center for Molecular Studies of the Cell (CEMC), Faculty of Medicine, Chile
| | - A Klip
- The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
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142
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Ackema KB, Hench J, Böckler S, Wang SC, Sauder U, Mergentaler H, Westermann B, Bard F, Frank S, Spang A. The small GTPase Arf1 modulates mitochondrial morphology and function. EMBO J 2014; 33:2659-75. [PMID: 25190516 DOI: 10.15252/embj.201489039] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The small GTPase Arf1 plays critical roles in membrane traffic by initiating the recruitment of coat proteins and by modulating the activity of lipid-modifying enzymes. Here, we report an unexpected but evolutionarily conserved role for Arf1 and the ArfGEF GBF1 at mitochondria. Loss of function of ARF-1 or GBF-1 impaired mitochondrial morphology and activity in Caenorhabditis elegans. Similarly, mitochondrial defects were observed in mammalian and yeast cells. In Saccharomyces cerevisiae, aberrant clusters of the mitofusin Fzo1 accumulated in arf1-11 mutants and were resolved by overexpression of Cdc48, an AAA-ATPase involved in ER and mitochondria-associated degradation processes. Yeast Arf1 co-fractionated with ER and mitochondrial membranes and interacted genetically with the contact site component Gem1. Furthermore, similar mitochondrial abnormalities resulted from knockdown of either GBF-1 or contact site components in worms, suggesting that the role of Arf1 in mitochondrial functioning is linked to ER-mitochondrial contacts. Thus, Arf1 is involved in mitochondrial homeostasis and dynamics, independent of its role in vesicular traffic.
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Affiliation(s)
- Karin B Ackema
- Growth and Development, Biozentrum University of Basel, Basel, Switzerland
| | - Jürgen Hench
- Division of Neuropathology, Institute of Pathology, University Hospital Basel, Basel, Switzerland
| | | | - Shyi Chyi Wang
- Institute for Molecular and Cell Biology, Singapore City, Singapore
| | - Ursula Sauder
- Microscopy Center, Biozentrum University of Basel, Basel, Switzerland
| | - Heidi Mergentaler
- Growth and Development, Biozentrum University of Basel, Basel, Switzerland
| | | | - Frédéric Bard
- Institute for Molecular and Cell Biology, Singapore City, Singapore
| | - Stephan Frank
- Division of Neuropathology, Institute of Pathology, University Hospital Basel, Basel, Switzerland
| | - Anne Spang
- Growth and Development, Biozentrum University of Basel, Basel, Switzerland
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143
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Elbaz-Alon Y, Rosenfeld-Gur E, Shinder V, Futerman AH, Geiger T, Schuldiner M. A dynamic interface between vacuoles and mitochondria in yeast. Dev Cell 2014; 30:95-102. [PMID: 25026036 DOI: 10.1016/j.devcel.2014.06.007] [Citation(s) in RCA: 276] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 04/14/2014] [Accepted: 06/09/2014] [Indexed: 12/18/2022]
Abstract
Cellular life depends on continuous transport of lipids and small molecules between mitochondria and the endomembrane system. Recently, endoplasmic reticulum-mitochondrial encounter structure (ERMES) was identified as an important yet nonessential contact for such transport. Using a high-content screen in yeast, we found a contact site, marked by Vam6/Vps39, between vacuoles (the yeast lysosomal compartment) and mitochondria, named vCLAMP (vacuole and mitochondria patch). vCLAMP is enriched with ion and amino-acid transporters and has a role in lipid relay between the endomembrane system and mitochondria. Critically, we show that mitochondria are dependent on having one of two contact sites, ERMES or vCLAMP. The absence of one causes expansion of the other, and elimination of both is lethal. Identification of vCLAMP adds to our ability to understand the complexity of interorganellar crosstalk.
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Affiliation(s)
- Yael Elbaz-Alon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Eden Rosenfeld-Gur
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Vera Shinder
- Electron Microscopy Unit, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Anthony H Futerman
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tamar Geiger
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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144
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Hanada K, Voelker D. Interorganelle trafficking of lipids: preface for the thematic review series. Traffic 2014; 15:889-94. [PMID: 25040538 DOI: 10.1111/tra.12193] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 07/01/2014] [Accepted: 07/01/2014] [Indexed: 12/18/2022]
Affiliation(s)
- Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
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145
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Hönscher C, Mari M, Auffarth K, Bohnert M, Griffith J, Geerts W, van der Laan M, Cabrera M, Reggiori F, Ungermann C. Cellular Metabolism Regulates Contact Sites between Vacuoles and Mitochondria. Dev Cell 2014; 30:86-94. [DOI: 10.1016/j.devcel.2014.06.006] [Citation(s) in RCA: 247] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 04/04/2014] [Accepted: 06/09/2014] [Indexed: 11/25/2022]
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146
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Ng S, De Clercq I, Van Aken O, Law SR, Ivanova A, Willems P, Giraud E, Van Breusegem F, Whelan J. Anterograde and retrograde regulation of nuclear genes encoding mitochondrial proteins during growth, development, and stress. MOLECULAR PLANT 2014; 7:1075-93. [PMID: 24711293 DOI: 10.1093/mp/ssu037] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Mitochondrial biogenesis and function in plants require the expression of over 1000 nuclear genes encoding mitochondrial proteins (NGEMPs). The expression of these genes is regulated by tissue-specific, developmental, internal, and external stimuli that result in a dynamic organelle involved in both metabolic and a variety of signaling processes. Although the metabolic and biosynthetic machinery of mitochondria is relatively well understood, the factors that regulate these processes and the various signaling pathways involved are only beginning to be identified at a molecular level. The molecular components of anterograde (nuclear to mitochondrial) and retrograde (mitochondrial to nuclear) signaling pathways that regulate the expression of NGEMPs interact with chloroplast-, growth-, and stress-signaling pathways in the cell at a variety of levels, with common components involved in transmission and execution of these signals. This positions mitochondria as important hubs for signaling in the cell, not only in direct signaling of mitochondrial function per se, but also in sensing and/or integrating a variety of other internal and external signals. This integrates and optimizes growth with energy metabolism and stress responses, which is required in both photosynthetic and non-photosynthetic cells.
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Affiliation(s)
- Sophia Ng
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Australia Joint Research Laboratory in Genomics and Nutriomics, College of Life Sciences, Zhejiang University, Hangzhou, 310058, P.R. China
| | - Inge De Clercq
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052 Gent, Belgium
| | - Olivier Van Aken
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Australia
| | - Simon R Law
- Department of Botany, ARC Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University, Bundoora 3086, Victoria, Australia
| | - Aneta Ivanova
- Department of Botany, ARC Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University, Bundoora 3086, Victoria, Australia
| | - Patrick Willems
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052 Gent, Belgium Department of Medical Protein Research and Department of Biochemistry, 9000 Ghent, Belgium
| | - Estelle Giraud
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Australia Present address: Illumina, ANZ, 1 International Court, Scoresby Victoria 3179, Australia
| | - Frank Van Breusegem
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052 Gent, Belgium
| | - James Whelan
- Department of Botany, ARC Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University, Bundoora 3086, Victoria, Australia
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147
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Daniele T, Schiaffino MV. Organelle biogenesis and interorganellar connections: Better in contact than in isolation. Commun Integr Biol 2014; 7:e29587. [PMID: 25346798 PMCID: PMC4203768 DOI: 10.4161/cib.29587] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 06/15/2014] [Indexed: 12/22/2022] Open
Abstract
Membrane contact sites (MCSs) allow the exchange of molecules and information between organelles, even when their membranes cannot fuse directly. In recent years, a number of functions have been attributed to these contacts, highlighting their critical role in cell homeostasis. Although inter-organellar connections typically involve the endoplasmic reticulum (ER), we recently reported the presence of a novel MCSs between melanosomes and mitochondria. Melanosome-mitochondrion contacts appear mediated by fibrillar bridges resembling the protein tethers linking mitochondria and the ER, both for their ultrastructural features and the involvement of Mitofusin 2. The frequency of these connections correlates spatially and timely with melanosome biogenesis, suggesting a functional link between the 2 processes and in general that organelle biogenesis in the secretory pathway requires interorganellar crosstalks at multiple steps. Here, we summarize the different functions attributed to MCSs, and discuss their possible relevance for the newly identified melanosome-mitochondrion liaison.
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Affiliation(s)
- Tiziana Daniele
- San Raffaele Scientific Institute; Experimental Imaging Center; Milan, Italy ; University of Genoa; Department of Experimental Medicine; Genoa, Italy
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148
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Abstract
The Golgi apparatus consists of disc-like cisternae, stretching around the nucleus through forces exerted by F-actin and the Golgi membrane protein GOLPH3. Farber-Katz et al. now report that DNA damage triggers Golgi dispersal and inhibits vesicular transport through DNA-PK-mediated GOLPH3 phosphorylation, thereby linking the DNA damage response to Golgi regulation.
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Affiliation(s)
- Marco Foiani
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare), Via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, Milan 20122, Italy.
| | - Jiri Bartek
- Danish Cancer Society Research Center, 2100 Copenhagen, Denmark; Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 771 15 Olomouc, Czech Republic.
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149
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A vertebrate model for the study of lipid binding/transfer protein function: Conservation of OSBP-related proteins between zebrafish and human. Biochem Biophys Res Commun 2014; 446:675-80. [DOI: 10.1016/j.bbrc.2013.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 12/02/2013] [Indexed: 01/12/2023]
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150
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Stordeur C, Puth K, Sáenz JP, Ernst R. Crosstalk of lipid and protein homeostasis to maintain membrane function. Biol Chem 2014; 395:313-26. [DOI: 10.1515/hsz-2013-0235] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/21/2013] [Indexed: 01/22/2023]
Abstract
Abstract
Biological membranes are a defining feature of cellular life. They serve as selective diffusion barriers, compartmentalize biochemical processes and protect the cellular milieu. We are only beginning to understand the principles underlying their homeostasis and the functional relevance of their complex compositions. Here, we summarize some recent evidences that suggest an intense crosstalk between the pathways of protein quality control and lipid homeostasis. We discuss paradigms of lipid regulation by protein degradation machineries and highlight the intricate connections between lipid droplet morphology, membrane biogenesis and ER-stress.
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