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Sun S, Zhao G, Jia M, Jiang Q, Li S, Wang H, Li W, Wang Y, Bian X, Zhao YG, Huang X, Yang G, Cai H, Pastor-Pareja JC, Ge L, Zhang C, Hu J. Stay in touch with the endoplasmic reticulum. SCIENCE CHINA. LIFE SCIENCES 2024; 67:230-257. [PMID: 38212460 DOI: 10.1007/s11427-023-2443-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 08/28/2023] [Indexed: 01/13/2024]
Abstract
The endoplasmic reticulum (ER), which is composed of a continuous network of tubules and sheets, forms the most widely distributed membrane system in eukaryotic cells. As a result, it engages a variety of organelles by establishing membrane contact sites (MCSs). These contacts regulate organelle positioning and remodeling, including fusion and fission, facilitate precise lipid exchange, and couple vital signaling events. Here, we systematically review recent advances and converging themes on ER-involved organellar contact. The molecular basis, cellular influence, and potential physiological functions for ER/nuclear envelope contacts with mitochondria, Golgi, endosomes, lysosomes, lipid droplets, autophagosomes, and plasma membrane are summarized.
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Affiliation(s)
- Sha Sun
- National Laboratory of Biomacromolecules, Institute of Biophysics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100101, China
| | - Gan Zhao
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Mingkang Jia
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Qing Jiang
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Shulin Li
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Haibin Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100101, China
| | - Wenjing Li
- Laboratory of Computational Biology & Machine Intelligence, School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yunyun Wang
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Xin Bian
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071, China.
| | - Yan G Zhao
- Brain Research Center, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Ge Yang
- Laboratory of Computational Biology & Machine Intelligence, School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Institute of Biophysics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Jose C Pastor-Pareja
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Institute of Neurosciences, Consejo Superior de Investigaciones Cientfflcas-Universidad Miguel Hernandez, San Juan de Alicante, 03550, Spain.
| | - Liang Ge
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| | - Chuanmao Zhang
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, 100871, China.
| | - Junjie Hu
- National Laboratory of Biomacromolecules, Institute of Biophysics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100101, China.
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Wang Y, Li Z, Wang X, Zhao Z, Jiao L, Liu R, Wang K, Ma R, Yang Y, Chen G, Wang Y, Bian X. Insights into membrane association of the SMP domain of extended synaptotagmin. Nat Commun 2023; 14:1504. [PMID: 36932127 PMCID: PMC10023780 DOI: 10.1038/s41467-023-37202-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 03/06/2023] [Indexed: 03/19/2023] Open
Abstract
The Synaptotagmin-like Mitochondrial-lipid-binding Protein (SMP) domain is a newly identified lipid transfer module present in proteins that regulate lipid homeostasis at membrane contact sites (MCSs). However, how the SMP domain associates with the membrane to extract and unload lipids is unclear. Here, we performed in vitro DNA brick-assisted lipid transfer assays and in silico molecular dynamics simulations to investigate the molecular basis of the membrane association by the SMP domain of extended synaptotagmin (E-Syt), which tethers the tubular endoplasmic reticulum (ER) to the plasma membrane (PM). We demonstrate that the SMP domain uses its tip region to recognize the extremely curved subdomain of tubular ER and the acidic-lipid-enriched PM for highly efficient lipid transfer. Supporting these findings, disruption of these mechanisms results in a defect in autophagosome biogenesis contributed by E-Syt. Our results suggest a model that provides a coherent picture of the action of the SMP domain at MCSs.
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Affiliation(s)
- Yunyun Wang
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai University, Tianjin, China
| | - Zhenni Li
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai University, Tianjin, China
| | - Xinyu Wang
- College of Life Sciences, Nankai University, Tianjin, China
| | - Ziyuan Zhao
- College of Life Sciences, Nankai University, Tianjin, China
| | - Li Jiao
- College of Life Sciences, Nankai University, Tianjin, China
| | - Ruming Liu
- College of Life Sciences, Nankai University, Tianjin, China
| | - Keying Wang
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Rui Ma
- College of Physical Science and Technology, Xiamen University, Xiamen, China
| | - Yang Yang
- Institute of Molecular Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Guo Chen
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai University, Tianjin, China
| | - Yong Wang
- College of Life Sciences, Zhejiang University, Hangzhou, China.
- The Provincial International Science and Technology Cooperation Base on Engineering Biology, International Campus of Zhejiang University, Haining, China.
| | - Xin Bian
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai University, Tianjin, China.
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3
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Hewitt VL, Miller-Fleming L, Twyning MJ, Andreazza S, Mattedi F, Prudent J, Polleux F, Vagnoni A, Whitworth AJ. Decreasing pdzd8-mediated mito-ER contacts improves organismal fitness and mitigates Aβ 42 toxicity. Life Sci Alliance 2022; 5:5/11/e202201531. [PMID: 35831024 PMCID: PMC9279675 DOI: 10.26508/lsa.202201531] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/01/2022] [Accepted: 07/01/2022] [Indexed: 02/02/2023] Open
Abstract
Mitochondria-ER contact sites (MERCs) orchestrate many important cellular functions including regulating mitochondrial quality control through mitophagy and mediating mitochondrial calcium uptake. Here, we identify and functionally characterize the Drosophila ortholog of the recently identified mammalian MERC protein, Pdzd8. We find that reducing pdzd8-mediated MERCs in neurons slows age-associated decline in locomotor activity and increases lifespan in Drosophila. The protective effects of pdzd8 knockdown in neurons correlate with an increase in mitophagy, suggesting that increased mitochondrial turnover may support healthy aging of neurons. In contrast, increasing MERCs by expressing a constitutive, synthetic ER-mitochondria tether disrupts mitochondrial transport and synapse formation, accelerates age-related decline in locomotion, and reduces lifespan. Although depletion of pdzd8 prolongs the survival of flies fed with mitochondrial toxins, it is also sufficient to rescue locomotor defects of a fly model of Alzheimer's disease expressing Amyloid β42 (Aβ42). Together, our results provide the first in vivo evidence that MERCs mediated by the tethering protein pdzd8 play a critical role in the regulation of mitochondrial quality control and neuronal homeostasis.
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Affiliation(s)
- Victoria L Hewitt
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
| | - Leonor Miller-Fleming
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Madeleine J Twyning
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Simonetta Andreazza
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Francesca Mattedi
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, IoPPN, King's College London, London, UK
| | - Julien Prudent
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Franck Polleux
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
- Mortimer B Zuckerman Mind Brain Behavior Institute, New York, NY, USA
- Kavli Institute for Brain Sciences, Columbia University Medical Center, New York, NY, USA
| | - Alessio Vagnoni
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, IoPPN, King's College London, London, UK
| | - Alexander J Whitworth
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
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4
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Al-Amri AH, Armstrong P, Amici M, Ligneul C, Rouse J, El-Asrag ME, Pantiru A, Vancollie VE, Ng HW, Ogbeta JA, Goodchild K, Ellegood J, Lelliott CJ, Mullins JG, Bretman A, Al-Ali R, Beetz C, Al-Gazali L, Al Shamsi A, Lerch JP, Mellor JR, Al Sayegh A, Ali M, Inglehearn CF, Clapcote SJ. PDZD8 Disruption Causes Cognitive Impairment in Humans, Mice, and Fruit Flies. Biol Psychiatry 2022; 92:323-334. [PMID: 35227461 PMCID: PMC9302898 DOI: 10.1016/j.biopsych.2021.12.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 12/16/2022]
Abstract
BACKGROUND The discovery of coding variants in genes that confer risk of intellectual disability (ID) is an important step toward understanding the pathophysiology of this common developmental disability. METHODS Homozygosity mapping, whole-exome sequencing, and cosegregation analyses were used to identify gene variants responsible for syndromic ID with autistic features in two independent consanguineous families from the Arabian Peninsula. For in vivo functional studies of the implicated gene's function in cognition, Drosophila melanogaster and mice with targeted interference of the orthologous gene were used. Behavioral, electrophysiological, and structural magnetic resonance imaging analyses were conducted for phenotypic testing. RESULTS Homozygous premature termination codons in PDZD8, encoding an endoplasmic reticulum-anchored lipid transfer protein, showed cosegregation with syndromic ID in both families. Drosophila melanogaster with knockdown of the PDZD8 ortholog exhibited impaired long-term courtship-based memory. Mice homozygous for a premature termination codon in Pdzd8 exhibited brain structural, hippocampal spatial memory, and synaptic plasticity deficits. CONCLUSIONS These data demonstrate the involvement of homozygous loss-of-function mutations in PDZD8 in a neurodevelopmental cognitive disorder. Model organisms with manipulation of the orthologous gene replicate aspects of the human phenotype and suggest plausible pathophysiological mechanisms centered on disrupted brain development and synaptic function. These findings are thus consistent with accruing evidence that synaptic defects are a common denominator of ID and other neurodevelopmental conditions.
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Affiliation(s)
- Ahmed H. Al-Amri
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom,Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom,National Genetic Centre, Royal Hospital, Muscat, Oman
| | - Paul Armstrong
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Mascia Amici
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Clemence Ligneul
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
| | - James Rouse
- School of Biology, University of Leeds, Leeds, United Kingdom
| | - Mohammed E. El-Asrag
- Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom,Department of Zoology, Faculty of Science, Benha University, Benha, Egypt,Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham
| | - Andreea Pantiru
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | | | - Hannah W.Y. Ng
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Jennifer A. Ogbeta
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Kirstie Goodchild
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Jacob Ellegood
- Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| | | | | | - Amanda Bretman
- School of Biology, University of Leeds, Leeds, United Kingdom
| | | | | | - Lihadh Al-Gazali
- Department of Paediatrics, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Aisha Al Shamsi
- Pediatrics Department, Tawam Hospital, Al Ain, United Arab Emirates
| | - Jason P. Lerch
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
| | - Jack R. Mellor
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Abeer Al Sayegh
- Genetics Department, Sultan Qaboos University Hospital, Muscat, Oman
| | - Manir Ali
- Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom
| | - Chris F. Inglehearn
- Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom
| | - Steven J. Clapcote
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom,Address correspondence to Steven J. Clapcote, Ph.D.
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5
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Qian T, Li C, Liu F, Xu K, Wan C, Liu Y, Yu H. Arabidopsis synaptotagmin 1 mediates lipid transport in a lipid composition-dependent manner. Traffic 2022; 23:346-356. [PMID: 35451158 DOI: 10.1111/tra.12844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 04/11/2022] [Accepted: 04/15/2022] [Indexed: 11/29/2022]
Abstract
The endoplasmic reticulum (ER) - plasma membrane (PM) contact sites (EPCSs) are structurally conserved in eukaryotes. The Arabidopsis ER-anchored synaptotagmin 1 (SYT1), enriched in EPCSs, plays a critical role in plant abiotic stress tolerance. It has become clear that SYT1 interacts with PM to mediate ER-PM connectivity. However, whether SYT1 performs additional functions at EPCSs remains unknown. Here, we reported that SYT1 efficiently transfers phospholipids between membranes. The lipid transfer activity of SYT1 is highly dependent on PI(4,5)P2 , a signal lipid accumulated at the PM under abiotic stress. Mechanically, while SYT1 transfers lipids fundamentally through the synaptotagmin-like mitochondrial-lipid-binding protein (SMP) domain, the efficient lipid transport requires the C2A domain-mediated membrane tethering. Interestingly, we observed that Ca2+ could stimulate SYT1-mediated lipid transport. In addition to PI(4,5)P2 , the Ca2+ activation requires the phosphatidylserine, another negatively charged lipid on the opposed membrane. Together, our studies identified Arabidopsis SYT1 as a lipid transfer protein at EPCSs and demonstrated it takes conserved as well as divergent mechanisms with other extend-synaptotagmins. The critical role of lipid composition and Ca2+ reveals SYT1-mediated lipid transport is highly regulated by signals in response to abiotic stresses.
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Affiliation(s)
- Tiantian Qian
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chenlu Li
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Furong Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Kai Xu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
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6
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Thomas FB, Omnus DJ, Bader JM, Chung GH, Kono N, Stefan CJ. Tricalbin proteins regulate plasma membrane phospholipid homeostasis. Life Sci Alliance 2022; 5:5/8/e202201430. [PMID: 35440494 PMCID: PMC9018018 DOI: 10.26508/lsa.202201430] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/03/2022] [Accepted: 04/04/2022] [Indexed: 12/26/2022] Open
Abstract
The evolutionarily conserved extended synaptotagmin (E-Syt) proteins are calcium-activated lipid transfer proteins that function at contacts between the ER and plasma membrane (ER-PM contacts). However, roles of the E-Syt family members in PM lipid organisation remain incomplete. Among the E-Syt family, the yeast tricalbin (Tcb) proteins are essential for PM integrity upon heat stress, but it is not known how they contribute to PM maintenance. Using quantitative lipidomics and microscopy, we find that the Tcb proteins regulate phosphatidylserine homeostasis at the PM. Moreover, upon heat-induced membrane stress, Tcb3 co-localises with the PM protein Sfk1 that is implicated in PM phospholipid asymmetry and integrity. The Tcb proteins also control the PM targeting of the known phosphatidylserine effector Pkc1 upon heat-induced stress. Phosphatidylserine has evolutionarily conserved roles in PM organisation, integrity, and repair. We propose that phospholipid regulation is an ancient essential function of E-Syt family members required for PM integrity.
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Affiliation(s)
- Ffion B Thomas
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Deike J Omnus
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Jakob M Bader
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Gary Hc Chung
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Nozomu Kono
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Christopher J Stefan
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
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7
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Reconstitution and biochemical studies of extended synaptotagmin-mediated lipid transport. Methods Enzymol 2022; 675:33-62. [DOI: 10.1016/bs.mie.2022.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Egea PF. Mechanisms of Non-Vesicular Exchange of Lipids at Membrane Contact Sites: Of Shuttles, Tunnels and, Funnels. Front Cell Dev Biol 2021; 9:784367. [PMID: 34912813 PMCID: PMC8667587 DOI: 10.3389/fcell.2021.784367] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Eukaryotic cells are characterized by their exquisite compartmentalization resulting from a cornucopia of membrane-bound organelles. Each of these compartments hosts a flurry of biochemical reactions and supports biological functions such as genome storage, membrane protein and lipid biosynthesis/degradation and ATP synthesis, all essential to cellular life. Acting as hubs for the transfer of matter and signals between organelles and throughout the cell, membrane contacts sites (MCSs), sites of close apposition between membranes from different organelles, are essential to cellular homeostasis. One of the now well-acknowledged function of MCSs involves the non-vesicular trafficking of lipids; its characterization answered one long-standing question of eukaryotic cell biology revealing how some organelles receive and distribute their membrane lipids in absence of vesicular trafficking. The endoplasmic reticulum (ER) in synergy with the mitochondria, stands as the nexus for the biosynthesis and distribution of phospholipids (PLs) throughout the cell by contacting nearly all other organelle types. MCSs create and maintain lipid fluxes and gradients essential to the functional asymmetry and polarity of biological membranes throughout the cell. Membrane apposition is mediated by proteinaceous tethers some of which function as lipid transfer proteins (LTPs). We summarize here the current state of mechanistic knowledge of some of the major classes of LTPs and tethers based on the available atomic to near-atomic resolution structures of several "model" MCSs from yeast but also in Metazoans; we describe different models of lipid transfer at MCSs and analyze the determinants of their specificity and directionality. Each of these systems illustrate fundamental principles and mechanisms for the non-vesicular exchange of lipids between eukaryotic membrane-bound organelles essential to a wide range of cellular processes such as at PL biosynthesis and distribution, lipid storage, autophagy and organelle biogenesis.
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Affiliation(s)
- Pascal F Egea
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
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9
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Aoyama-Ishiwatari S, Hirabayashi Y. Endoplasmic Reticulum-Mitochondria Contact Sites-Emerging Intracellular Signaling Hubs. Front Cell Dev Biol 2021; 9:653828. [PMID: 34095118 PMCID: PMC8172986 DOI: 10.3389/fcell.2021.653828] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 04/06/2021] [Indexed: 01/04/2023] Open
Abstract
It has become apparent that our textbook illustration of singular isolated organelles is obsolete. In reality, organelles form complex cooperative networks involving various types of organelles. Light microscopic and ultrastructural studies have revealed that mitochondria-endoplasmic reticulum (ER) contact sites (MERCSs) are abundant in various tissues and cell types. Indeed, MERCSs have been proposed to play critical roles in various biochemical and signaling functions such as Ca2+ homeostasis, lipid transfer, and regulation of organelle dynamics. While numerous proteins involved in these MERCS-dependent functions have been reported, how they coordinate and cooperate with each other has not yet been elucidated. In this review, we summarize the functions of mammalian proteins that localize at MERCSs and regulate their formation. We also discuss potential roles of the MERCS proteins in regulating multiple organelle contacts.
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Affiliation(s)
| | - Yusuke Hirabayashi
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Tokyo, Japan
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10
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Qian T, Li C, He R, Wan C, Liu Y, Yu H. Calcium-dependent and -independent lipid transfer mediated by tricalbins in yeast. J Biol Chem 2021; 296:100729. [PMID: 33933446 PMCID: PMC8163979 DOI: 10.1016/j.jbc.2021.100729] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/23/2021] [Accepted: 04/28/2021] [Indexed: 11/12/2022] Open
Abstract
Membrane contact sites (MCSs) formed between the endoplasmic reticulum (ER) and the plasma membrane (PM) provide a platform for nonvesicular lipid exchange. The ER-anchored tricalbins (Tcb1, Tcb2, and Tcb3) are critical tethering factors at ER–PM MCSs in yeast. Tricalbins possess a synaptotagmin-like mitochondrial-lipid-binding protein (SMP) domain and multiple Ca2+-binding C2 domains. Although tricalbins have been suggested to be involved in lipid exchange at the ER–PM MCSs, it remains unclear whether they directly mediate lipid transport. Here, using in vitro lipid transfer assays, we discovered that tricalbins are capable of transferring phospholipids between membranes. Unexpectedly, while its lipid transfer activity was markedly elevated by Ca2+, Tcb3 constitutively transferred lipids even in the absence of Ca2+. The stimulatory activity of Ca2+ on Tcb3 required intact Ca2+-binding sites on both the C2C and C2D domains of Tcb3, while Ca2+-independent lipid transport was mediated by the SMP domain that transferred lipids via direct interactions with phosphatidylserine and other negatively charged lipid molecules. These findings establish tricalbins as lipid transfer proteins, and reveal Ca2+-dependent and -independent lipid transfer activities mediated by these tricalbins, providing new insights into their mechanism in maintaining PM integrity at ER–PM MCSs.
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Affiliation(s)
- Tiantian Qian
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chenlu Li
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ruyue He
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, USA
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
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11
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Hewlett B, Singh NP, Vannier C, Galli T. ER-PM Contact Sites - SNARING Actors in Emerging Functions. Front Cell Dev Biol 2021; 9:635518. [PMID: 33681218 PMCID: PMC7928305 DOI: 10.3389/fcell.2021.635518] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/21/2021] [Indexed: 11/13/2022] Open
Abstract
The compartmentalisation achieved by confining cytoplasm into membrane-enclosed organelles in eukaryotic cells is essential for maintaining vital functions including ATP production, synthetic and degradative pathways. While intracellular organelles are highly specialised in these functions, the restricting membranes also impede exchange of molecules responsible for the synchronised and responsive cellular activities. The initial identification of contact sites between the ER and plasma membrane (PM) provided a potential candidate structure for communication between organelles without mixing by fusion. Over the past decades, research has revealed a far broader picture of the events. Membrane contact sites (MCSs) have been recognized as increasingly important actors in cell differentiation, plasticity and maintenance, and, upon dysfunction, responsible for pathological conditions such as cancer and neurodegenerative diseases. Present in multiple organelles and cell types, MCSs promote transport of lipids and Ca2+ homoeostasis, with a range of associated protein families. Interestingly, each MCS displays a unique molecular signature, adapted to organelle functions. This review will explore the literature describing the molecular components and interactions taking place at ER-PM contact sites, their functions, and implications in eukaryotic cells, particularly neurons, with emphasis on lipid transfer proteins and emerging function of SNAREs.
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Affiliation(s)
- Bailey Hewlett
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Neha Pratap Singh
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Christian Vannier
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Thierry Galli
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France.,GHU PARIS Psychiatrie and Neurosciences, Paris, France
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12
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Li C, Qian T, He R, Wan C, Liu Y, Yu H. Endoplasmic Reticulum-Plasma Membrane Contact Sites: Regulators, Mechanisms, and Physiological Functions. Front Cell Dev Biol 2021; 9:627700. [PMID: 33614657 PMCID: PMC7889955 DOI: 10.3389/fcell.2021.627700] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/13/2021] [Indexed: 12/13/2022] Open
Abstract
The endoplasmic reticulum (ER) forms direct membrane contact sites with the plasma membrane (PM) in eukaryotic cells. These ER-PM contact sites play essential roles in lipid homeostasis, ion dynamics, and cell signaling, which are carried out by protein-protein or protein-lipid interactions. Distinct tethering factors dynamically control the architecture of ER-PM junctions in response to intracellular signals or external stimuli. The physiological roles of ER-PM contact sites are dependent on a variety of regulators that individually or cooperatively perform functions in diverse cellular processes. This review focuses on proteins functioning at ER-PM contact sites and highlights the recent progress in their mechanisms and physiological roles.
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Affiliation(s)
- Chenlu Li
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Tiantian Qian
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ruyue He
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Chun Wan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, United States
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
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13
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Harper CS, White AJ, Lackner LL. The multifunctional nature of mitochondrial contact site proteins. Curr Opin Cell Biol 2020; 65:58-65. [PMID: 32208350 PMCID: PMC7771046 DOI: 10.1016/j.ceb.2020.02.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 02/15/2020] [Indexed: 11/19/2022]
Abstract
Mitochondria make physical contact with nearly every other membrane in the cell, and these contacts have a wide variety of functions that are carried out by proteins that reside at the sites of contact. Over the past decade, tremendous insight into the identity and functions of proteins localized to mitochondrial contact sites has been gained. In doing so, it has become clear that one protein or protein complex can contribute to contact site formation and function in a wide variety of ways. Thus, complex and often surprising relationships between the roles of a mitochondrial contact site and its multifunctional resident proteins continue to be unraveled.
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Affiliation(s)
- Clare S Harper
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Antoineen J White
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Laura L Lackner
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
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14
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Elbaz-Alon Y, Guo Y, Segev N, Harel M, Quinnell DE, Geiger T, Avinoam O, Li D, Nunnari J. PDZD8 interacts with Protrudin and Rab7 at ER-late endosome membrane contact sites associated with mitochondria. Nat Commun 2020; 11:3645. [PMID: 32686675 PMCID: PMC7371716 DOI: 10.1038/s41467-020-17451-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 06/23/2020] [Indexed: 12/02/2022] Open
Abstract
Endosomes are compositionally dynamic organelles that regulate signaling, nutrient status and organelle quality by specifying whether material entering the cells will be shuttled back to the cell surface or degraded by the lysosome. Recently, membrane contact sites (MCSs) between the endoplasmic reticulum (ER) and endosomes have emerged as important players in endosomal protein sorting, dynamics and motility. Here, we show that PDZD8, a Synaptotagmin-like Mitochondrial lipid-binding Proteins (SMP) domain-containing ER transmembrane protein, utilizes distinct domains to interact with Rab7-GTP and the ER transmembrane protein Protrudin and together these components localize to an ER-late endosome MCS. At these ER-late endosome MCSs, mitochondria are also recruited to form a three-way contact. Thus, our data indicate that PDZD8 is a shared component of two distinct MCSs and suggest a role for SMP-mediated lipid transport in the regulation of endosome function. Membrane contact sites between organelles have been shown to play important biological roles. Here, the authors show that at the ER, PDZD8 associates with Protrudin and also with Rab7 endosomes and recruits mitochondria to form three-way contacts.
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Affiliation(s)
- Yael Elbaz-Alon
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA, USA. .,Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
| | - Yuting Guo
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Nadav Segev
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Harel
- Department of Human Molecular Genetics and Biochemistry, Tel-Aviv University, Tel Aviv-Yafo, Israel
| | - Daniel E Quinnell
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA, USA
| | - Tamar Geiger
- Department of Human Molecular Genetics and Biochemistry, Tel-Aviv University, Tel Aviv-Yafo, Israel
| | - Ori Avinoam
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Dong Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jodi Nunnari
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA, USA.
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15
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Kornmann B. The endoplasmic reticulum-mitochondria encounter structure: coordinating lipid metabolism across membranes. Biol Chem 2020; 401:811-820. [DOI: 10.1515/hsz-2020-0102] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 02/05/2020] [Indexed: 02/06/2023]
Abstract
AbstractEndosymbiosis, the beginning of a collaboration between an archaeon and a bacterium and a founding step in the evolution of eukaryotes, owes its success to the establishment of communication routes between the host and the symbiont to allow the exchange of metabolites. As far as lipids are concerned, it is the host that has learnt the symbiont’s language, as eukaryote lipids appear to have been borrowed from the bacterial symbiont. Mitochondria exchange lipids with the rest of the cell at membrane contact sites. In fungi, the endoplasmic reticulum-mitochondria encounter structure (ERMES) is one of the best understood membrane tethering complexes. Its discovery has yielded crucial insight into the mechanisms of intracellular lipid trafficking. Despite a wealth of data, our understanding of ERMES formation and its exact role(s) remains incomplete. Here, I endeavour to summarise our knowledge on the ERMES complex and to identify lingering gaps.
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Affiliation(s)
- Benoît Kornmann
- Department of Biochemistry, University of Oxford, South Parks Rd, Oxford OX1 3QU, UK
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16
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Levy A, Tilsner J. Creating Contacts Between Replication and Movement at Plasmodesmata - A Role for Membrane Contact Sites in Plant Virus Infections? FRONTIERS IN PLANT SCIENCE 2020; 11:862. [PMID: 32719692 PMCID: PMC7350983 DOI: 10.3389/fpls.2020.00862] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 05/27/2020] [Indexed: 05/23/2023]
Abstract
To infect their hosts and cause disease, plant viruses must replicate within cells and move throughout the plant both locally and systemically. RNA virus replication occurs on the surface of various cellular membranes, whose shape and composition become extensively modified in the process. Membrane contact sites (MCS) can mediate non-vesicular lipid-shuttling between different membranes and viruses co-opt components of these structures to make their membrane environment suitable for replication. Whereas animal viruses exit and enter cells when moving throughout their host, the rigid wall of plant cells obstructs this pathway and plant viruses therefore move between cells symplastically through plasmodesmata (PD). PD are membranous channels connecting nearly all plant cells and are now viewed to constitute a specialized type of endoplasmic reticulum (ER)-plasma membrane (PM) MCS themselves. Thus, both replication and movement of plant viruses rely on MCS. However, recent work also suggests that for some viruses, replication and movement are closely coupled at ER-PM MCS at the entrances of PD. Movement-coupled replication at PD may be distinct from the main bulk of replication and virus accumulation, which produces progeny virions for plant-to-plant transmission. Thus, MCS play a central role in plant virus infections, and may provide a link between two essential steps in the viral life cycle, replication and movement. Here, we provide an overview of plant virus-MCS interactions identified to date, and place these in the context of the connection between viral replication and cell-to-cell movement.
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Affiliation(s)
- Amit Levy
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, United States
| | - Jens Tilsner
- Biomedical Sciences Research Complex, The University of St. Andrews, St. Andrews, United Kingdom
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
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17
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Pemberton JG, Kim YJ, Balla T. Integrated regulation of the phosphatidylinositol cycle and phosphoinositide-driven lipid transport at ER-PM contact sites. Traffic 2019; 21:200-219. [PMID: 31650663 DOI: 10.1111/tra.12709] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/02/2019] [Accepted: 10/16/2019] [Indexed: 12/20/2022]
Abstract
Among the structural phospholipids that form the bulk of eukaryotic cell membranes, phosphatidylinositol (PtdIns) is unique in that it also serves as the common precursor for low-abundance regulatory lipids, collectively referred to as polyphosphoinositides (PPIn). The metabolic turnover of PPIn species has received immense attention because of the essential functions of these lipids as universal regulators of membrane biology and their dysregulation in numerous human pathologies. The diverse functions of PPIn lipids occur, in part, by orchestrating the spatial organization and conformational dynamics of peripheral or integral membrane proteins within defined subcellular compartments. The emerging role of stable contact sites between adjacent membranes as specialized platforms for the coordinate control of ion exchange, cytoskeletal dynamics, and lipid transport has also revealed important new roles for PPIn species. In this review, we highlight the importance of membrane contact sites formed between the endoplasmic reticulum (ER) and plasma membrane (PM) for the integrated regulation of PPIn metabolism within the PM. Special emphasis will be placed on non-vesicular lipid transport during control of the PtdIns biosynthetic cycle as well as toward balancing the turnover of the signaling PPIn species that define PM identity.
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Affiliation(s)
- Joshua G Pemberton
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, Maryland
| | - Yeun Ju Kim
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, Maryland
| | - Tamas Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, Maryland
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18
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Collado J, Kalemanov M, Campelo F, Bourgoint C, Thomas F, Loewith R, Martínez-Sánchez A, Baumeister W, Stefan CJ, Fernández-Busnadiego R. Tricalbin-Mediated Contact Sites Control ER Curvature to Maintain Plasma Membrane Integrity. Dev Cell 2019; 51:476-487.e7. [PMID: 31743662 PMCID: PMC6863395 DOI: 10.1016/j.devcel.2019.10.018] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 09/23/2019] [Accepted: 10/16/2019] [Indexed: 12/23/2022]
Abstract
Membrane contact sites (MCS) between the endoplasmic reticulum (ER) and the plasma membrane (PM) play fundamental roles in all eukaryotic cells. ER-PM MCS are particularly abundant in Saccharomyces cerevisiae, where approximately half of the PM surface is covered by cortical ER (cER). Several proteins, including Ist2, Scs2/22, and Tcb1/2/3 are implicated in cER formation, but the specific roles of these molecules are poorly understood. Here, we use cryo-electron tomography to show that ER-PM tethers are key determinants of cER morphology. Notably, Tcb proteins (tricalbins) form peaks of extreme curvature on the cER membrane facing the PM. Combined modeling and functional assays suggest that Tcb-mediated cER peaks facilitate the transport of lipids between the cER and the PM, which is necessary to maintain PM integrity under heat stress. ER peaks were also present at other MCS, implying that membrane curvature enforcement may be a widespread mechanism to regulate MCS function.
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Affiliation(s)
- Javier Collado
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried 82152, Germany; Institute of Neuropathology, University Medical Center Göttingen, Göttingen 37099, Germany; Graduate School of Quantitative Biosciences Munich, Munich 81337, Germany
| | - Maria Kalemanov
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried 82152, Germany; Graduate School of Quantitative Biosciences Munich, Munich 81337, Germany
| | - Felix Campelo
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels 08860, Spain
| | - Clélia Bourgoint
- Department of Molecular Biology, University of Geneva, Geneva 1211, Switzerland
| | - Ffion Thomas
- MRC Laboratory for Molecular Cell Biology, University College London, London, WC1E 6BT, UK
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, Geneva 1211, Switzerland; Swiss National Centre for Competence in Research, Program Chemical Biology, Geneva 1211, Switzerland
| | - Antonio Martínez-Sánchez
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Christopher J Stefan
- MRC Laboratory for Molecular Cell Biology, University College London, London, WC1E 6BT, UK
| | - Rubén Fernández-Busnadiego
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried 82152, Germany; Institute of Neuropathology, University Medical Center Göttingen, Göttingen 37099, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
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19
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Veeresh P, Kaur H, Sarmah D, Mounica L, Verma G, Kotian V, Kesharwani R, Kalia K, Borah A, Wang X, Dave KR, Rodriguez AM, Yavagal DR, Bhattacharya P. Endoplasmic reticulum-mitochondria crosstalk: from junction to function across neurological disorders. Ann N Y Acad Sci 2019; 1457:41-60. [PMID: 31460675 DOI: 10.1111/nyas.14212] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 07/12/2019] [Accepted: 07/19/2019] [Indexed: 12/12/2022]
Abstract
The endoplasmic reticulum (ER) and mitochondria are fundamental organelles highly interconnected with a specialized set of proteins in cells. ER-mitochondrial interconnections form specific microdomains, called mitochondria-associated ER membranes, that have been found to play important roles in calcium signaling and lipid homeostasis, and more recently in mitochondrial dynamics, inflammation, and autophagy. It is not surprising that perturbations in ER-mitochondria connections can result in the progression of disease, especially neurological disorders; hence, their architecture and regulation are crucial in determining the fate of cells and disease. The molecular identity of the specialized proteins regulating ER-mitochondrial crosstalk remains unclear. Our discussion here describes the physical and functional crosstalk between these two dynamic organelles and emphasizes the outcome of altered ER-mitochondrial interconnections in neurological disorders.
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Affiliation(s)
- Pabbala Veeresh
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, Gandhinagar, Gujarat, India
| | - Harpreet Kaur
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, Gandhinagar, Gujarat, India
| | - Deepaneeta Sarmah
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, Gandhinagar, Gujarat, India.,Institut Mondor de Recherche Biomédicale (IMRB), INSERM U955, Université Paris-Est, UMR-S955, UPEC, Cretéil, France
| | - Leela Mounica
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, Gandhinagar, Gujarat, India
| | - Geetesh Verma
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, Gandhinagar, Gujarat, India
| | - Vignesh Kotian
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, Gandhinagar, Gujarat, India
| | - Radhika Kesharwani
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, Gandhinagar, Gujarat, India
| | - Kiran Kalia
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, Gandhinagar, Gujarat, India
| | - Anupom Borah
- Cellular and Molecular Neurobiology Laboratory, Department of Life Science and Bioinformatics, Assam University, Silchar, Assam, India
| | - Xin Wang
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Kunjan R Dave
- Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida
| | - Anne-Marie Rodriguez
- Institut Mondor de Recherche Biomédicale (IMRB), INSERM U955, Université Paris-Est, UMR-S955, UPEC, Cretéil, France
| | - Dileep R Yavagal
- Department of Neurology and Neurosurgery, University of Miami Miller School of Medicine, Miami, Florida
| | - Pallab Bhattacharya
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER) Ahmedabad, Gandhinagar, Gujarat, India
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20
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A programmable DNA-origami platform for studying lipid transfer between bilayers. Nat Chem Biol 2019; 15:830-837. [PMID: 31320758 PMCID: PMC6650167 DOI: 10.1038/s41589-019-0325-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 06/14/2019] [Indexed: 02/07/2023]
Abstract
Non-vesicular lipid transport between bilayers at membrane contact sites plays important physiological roles. Mechanistic insight into the action of lipid transport proteins localized at these sites (bridge/tunnel versus shuttle models) requires a determination of the distance between bilayers at which this transport can occur. Here, we developed DNA-origami nanostructures to organize size-defined liposomes at precise distances and used them to study lipid transfer by the SMP domain of E-Syt1. Pairs of DNA-ring-templated donor and acceptor liposomes were docked through DNA pillars, which determined their distance. The SMP domain was anchored to donor liposomes via an unstructured linker and lipid transfer was assessed via a FRET-based assay. We show that lipid transfer can occur over distances that exceed the length of SMP dimer, compatible with a shuttle model. The DNA nanostructures developed here can be adapted to study other processes occurring where two membranes are closely apposed to each other.
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21
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Bian X, De Camilli P. In Vitro Assays to Measure the Membrane Tethering and Lipid Transport Activities of the Extended Synaptotagmins. Methods Mol Biol 2019; 1949:201-212. [PMID: 30790258 DOI: 10.1007/978-1-4939-9136-5_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
The three extended synaptotagmins (E-Syts) are endoplasmic reticulum (ER)-localized membrane proteins that mediate tethering of the ER to the plasma membrane (PM) via C2 domain-dependent interactions regulated by Ca2+ and/or PI(4,5)P2. The E-Syts also contains a Synaptotagmin-like Mitochondrial lipid-binding Protein (SMP) domain, a lipid-harboring module through which they mediate lipid transport between the two adjacent membranes. Here, we describe in vitro liposome-based methods to study the membrane tethering and lipid transport functions of E-Syt1. Its membrane tethering activity is monitored through a turbidity-based assay, and its lipid transport property is analyzed via fluorescence resonance energy transfer (FRET)-based assay. These in vitro methods have enabled us to gain insight into the mechanism of action and regulation of E-Syt1, such as the role of Ca2+ in releasing E-Syt1 from an autoinhibitory conformation. The same methods could be adapted to the study of other lipid transport proteins that function at membrane contact sites.
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Affiliation(s)
- Xin Bian
- Department of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration, and Repair, and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Pietro De Camilli
- Department of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration, and Repair, and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA.
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22
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Lackner LL. The Expanding and Unexpected Functions of Mitochondria Contact Sites. Trends Cell Biol 2019; 29:580-590. [PMID: 30929794 DOI: 10.1016/j.tcb.2019.02.009] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 10/27/2022]
Abstract
Mitochondria make functionally relevant contacts with most, if not all, other organelles in the cell. These contacts impact on mitochondrial behavior and function as well as on a wide variety of cellular functions. Many recent advances have been made in the rapidly growing field of mitochondria contact site biology, and these advances have expanded the known functions of mitochondria contact sites in exciting and unexpected ways.
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Affiliation(s)
- Laura L Lackner
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
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23
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Hanada K. Lipid transfer proteins rectify inter-organelle flux and accurately deliver lipids at membrane contact sites. J Lipid Res 2018; 59:1341-1366. [PMID: 29884707 PMCID: PMC6071762 DOI: 10.1194/jlr.r085324] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 05/24/2018] [Indexed: 12/22/2022] Open
Abstract
The endoplasmic reticulum (ER) is the main center for the synthesis of various lipid types in cells, and newly synthesized lipids are delivered from the ER to other organelles. In the past decade, various lipid transfer proteins (LTPs) have been recognized as mediators of lipid transport from the ER to other organelles; inter-organelle transport occurs at membrane contact sites (MCSs) and in a nonvesicular manner. Although the intermembrane transfer reaction catalyzed by LTPs is an equilibrium reaction, various types of newly synthesized lipids are transported unidirectionally in cells. This review provides a brief history of the inter-organelle trafficking of lipids and summarizes the structural and biochemical characteristics of the ceramide transport protein (CERT) as a typical LTP acting at MCSs. In addition, this review compares several LTP-mediated inter-organelle lipid trafficking systems and proposes that LTPs generate unidirectional fluxes of specific lipids between different organelles by indirect coupling with the metabolic reactions that occur in specific organelles. Moreover, the available data also suggest that the major advantage of LTP-mediated lipid transport at MCSs may be the accuracy of delivery. Finally, how cholesterol is enriched in the plasma membrane is discussed from a thermodynamic perspective.
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Affiliation(s)
- Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan
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24
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Wideman JG, Balacco DL, Fieblinger T, Richards TA. PDZD8 is not the 'functional ortholog' of Mmm1, it is a paralog. F1000Res 2018; 7:1088. [PMID: 30109028 PMCID: PMC6069729 DOI: 10.12688/f1000research.15523.1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/06/2018] [Indexed: 11/20/2022] Open
Abstract
Authors of a recent paper demonstrate that, like ERMES (ER-mitochondria encounter structure) in fungal cells, PDZD8 (PDZ domain containing 8) tethers mitochondria to the ER in mammalian cells. However, identifying PDZD8 as a "functional ortholog" of yeast Mmm1 (maintenance of mitochondrial morphology protein 1) is at odds with the phylogenetic data. PDZD8 and Mmm1 are paralogs, not orthologs, which affects the interpretation of the data with respect to the evolution of ER-mitochondria tethering. Our phylogenetic analyses show that PDZD8 co-occurs with ERMES components in lineages closely related to animals solidifying its identity as a paralog of Mmm1. Additionally, we identify two related paralogs, one specific to flagellated fungi, and one present only in unicellular relatives of animals. These results point to a complex evolutionary history of ER-mitochondria tethering involving multiple gene gains and losses in the lineage leading to animals and fungi.
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Affiliation(s)
- Jeremy G Wideman
- Department of Biosciences, University of Exeter, Exeter, EX4 4QD, UK.,Wissenschaftskolleg zu Berlin, Berlin, 14193, Germany
| | - Dario L Balacco
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Tim Fieblinger
- Wissenschaftskolleg zu Berlin, Berlin, 14193, Germany.,Basal Ganglia Pathophysiology Unit, Department of Experimental Medical Science, Lund University, Lund, 22184, Sweden
| | - Thomas A Richards
- Department of Biosciences, University of Exeter, Exeter, EX4 4QD, UK
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25
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Hirabayashi Y, Kwon SK, Paek H, Pernice WM, Paul MA, Lee J, Erfani P, Raczkowski A, Petrey DS, Pon LA, Polleux F. ER-mitochondria tethering by PDZD8 regulates Ca 2+ dynamics in mammalian neurons. Science 2018; 358:623-630. [PMID: 29097544 DOI: 10.1126/science.aan6009] [Citation(s) in RCA: 317] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 08/21/2017] [Accepted: 09/20/2017] [Indexed: 01/06/2023]
Abstract
Interfaces between organelles are emerging as critical platforms for many biological responses in eukaryotic cells. In yeast, the ERMES complex is an endoplasmic reticulum (ER)-mitochondria tether composed of four proteins, three of which contain a SMP (synaptotagmin-like mitochondrial-lipid binding protein) domain. No functional ortholog for any ERMES protein has been identified in metazoans. Here, we identified PDZD8 as an ER protein present at ER-mitochondria contacts. The SMP domain of PDZD8 is functionally orthologous to the SMP domain found in yeast Mmm1. PDZD8 was necessary for the formation of ER-mitochondria contacts in mammalian cells. In neurons, PDZD8 was required for calcium ion (Ca2+) uptake by mitochondria after synaptically induced Ca2+-release from ER and thereby regulated cytoplasmic Ca2+ dynamics. Thus, PDZD8 represents a critical ER-mitochondria tethering protein in metazoans. We suggest that ER-mitochondria coupling is involved in the regulation of dendritic Ca2+ dynamics in mammalian neurons.
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Affiliation(s)
- Yusuke Hirabayashi
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.,Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Tokyo, Japan
| | - Seok-Kyu Kwon
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Hunki Paek
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Wolfgang M Pernice
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Maëla A Paul
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Jinoh Lee
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Parsa Erfani
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA.,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Ashleigh Raczkowski
- Simons Electron Microscopy Center, New York Structural Biology Center (NYSBC), New York, NY 10027, USA
| | - Donald S Petrey
- Center for Computational Biology and Bioinformatics, Department of Systems Biology, Columbia University, New York, NY 10032, USA.,Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Liza A Pon
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA.,Institute of Human Nutrition, Columbia University, New York, NY 10032, USA
| | - Franck Polleux
- Department of Neuroscience, Columbia University Medical Center, Columbia University, New York, NY 10027, USA. .,Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.,Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
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Bian X, Saheki Y, De Camilli P. Ca 2+ releases E-Syt1 autoinhibition to couple ER-plasma membrane tethering with lipid transport. EMBO J 2018; 37:219-234. [PMID: 29222176 PMCID: PMC5770786 DOI: 10.15252/embj.201797359] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 11/08/2017] [Accepted: 11/10/2017] [Indexed: 11/09/2022] Open
Abstract
The extended synaptotagmins (E-Syts) are endoplasmic reticulum (ER) proteins that bind the plasma membrane (PM) via C2 domains and transport lipids between them via SMP domains. E-Syt1 tethers and transports lipids in a Ca2+-dependent manner, but the role of Ca2+ in this regulation is unclear. Of the five C2 domains of E-Syt1, only C2A and C2C contain Ca2+-binding sites. Using liposome-based assays, we show that Ca2+ binding to C2C promotes E-Syt1-mediated membrane tethering by releasing an inhibition that prevents C2E from interacting with PI(4,5)P2-rich membranes, as previously suggested by studies in semi-permeabilized cells. Importantly, Ca2+ binding to C2A enables lipid transport by releasing a charge-based autoinhibitory interaction between this domain and the SMP domain. Supporting these results, E-Syt1 constructs defective in Ca2+ binding in either C2A or C2C failed to rescue two defects in PM lipid homeostasis observed in E-Syts KO cells, delayed diacylglycerol clearance from the PM and impaired Ca2+-triggered phosphatidylserine scrambling. Thus, a main effect of Ca2+ on E-Syt1 is to reverse an autoinhibited state and to couple membrane tethering with lipid transport.
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Affiliation(s)
- Xin Bian
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT, USA
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, USA
| | - Yasunori Saheki
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT, USA
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, USA
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Pietro De Camilli
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT, USA
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, USA
- Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
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27
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Pernice WM, Swayne TC, Boldogh IR, Pon LA. Mitochondrial Tethers and Their Impact on Lifespan in Budding Yeast. Front Cell Dev Biol 2018; 5:120. [PMID: 29359129 PMCID: PMC5766657 DOI: 10.3389/fcell.2017.00120] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 12/20/2017] [Indexed: 12/26/2022] Open
Abstract
Tethers that link mitochondria to other organelles are critical for lipid and calcium transport as well as mitochondrial genome replication and fission of the organelle. Here, we review recent advances in the characterization of interorganellar mitochondrial tethers in the budding yeast, Saccharomyces cerevisiae. We specifically focus on evidence for a role for mitochondrial tethers that anchor mitochondria to specific regions within yeast cells. These tethering events contribute to two processes that are critical for normal replicative lifespan: inheritance of fitter mitochondria by daughter cells, and retention of a small pool of higher-functioning mitochondria in mother cells. Since asymmetric inheritance of mitochondria also occurs in human mammary stem-like cells, it is possible that mechanisms underlying mitochondrial segregation in yeast also operate in other cell types.
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Affiliation(s)
- Wolfgang M Pernice
- Department of Pathology and Cell Biology, Columbia University, New York, NY, United States
| | - Theresa C Swayne
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, United States
| | - Istvan R Boldogh
- Department of Pathology and Cell Biology, Columbia University, New York, NY, United States
| | - Liza A Pon
- Department of Pathology and Cell Biology, Columbia University, New York, NY, United States.,Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, United States
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28
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Huang R, Zhao J, Liu J, Wang Y, Han S, Zhao H. Genome-wide analysis and expression profiles of NTMC2 family genes in Oryza sativa. Gene 2017; 637:130-137. [PMID: 28947303 DOI: 10.1016/j.gene.2017.09.046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/06/2017] [Accepted: 09/21/2017] [Indexed: 10/18/2022]
Abstract
N-terminal-TM-C2 domain proteins (NTMC2), which share domain architecture and sequence similarity to synaptotagmins (Syts) in mammals and FAM62 (extended Syts) in metazoans, form a small gene family in plants. Previous studies showed that the Arabidopsis thaliana NTMC2 type 1.1 protein (NTMC2T1.1, named AtSyt1) possesses calcium- and membrane-binding activities that allow it to function in a plasma membrane repair pathway induced by stress. However, we lack understanding of the diverse biological roles of plant NTMC2 family genes. In this study, a total of 13 OsNTMC2 genes was identified through a comprehensive bioinformatics analysis of the rice (Oryza sativa L.) genome and classified into six OsNTMC2 groups (OsNTMC2T1 to OsNTMC2T6) based on phylogeny and motif constitution. OsNTMC2T1 to OsNTMC2T3 have two calcium-binding domains (C2A and C2B), but OsNTMC2T4 to OsNTMC2T6 have single C2 domain. The expression profiles of OsNTMC2 genes were analysed at different stages of vegetative and reproductive development. This analysis revealed that at least one OsNTMC2 gene was abundantly expressed at each stage of development. These results should facilitate research on this gene family and provide new insights elucidating their functions in higher plants.
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Affiliation(s)
- Rui Huang
- College of Medicine, Northwest Minzu University, Lanzhou 730030, China; Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Jin Zhao
- College of Medicine, Northwest Minzu University, Lanzhou 730030, China
| | - Jin Liu
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Yingdian Wang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Shengcheng Han
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
| | - Heping Zhao
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
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29
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Hoffmann PC, Kukulski W. Perspective on architecture and assembly of membrane contact sites. Biol Cell 2017; 109:400-408. [PMID: 28960356 DOI: 10.1111/boc.201700031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 09/21/2017] [Accepted: 09/21/2017] [Indexed: 01/25/2023]
Abstract
Membrane contact sites (MCS) are platforms of physical contact between different organelles. They are formed through interactions involving lipids and proteins, and function in processes such as calcium and lipid exchange, metabolism and organelle biogenesis. In this article, we discuss emerging questions regarding the architecture, organisation and assembly of MCS, such as: What is the contribution of different components to the interaction between organelles? How is the specific composition of different types of membrane contacts sites established and maintained? How are proteins and lipids spatially organised at MCS and how does that influence their function? How dynamic are MCS on the molecular and ultrastructural level? We highlight current state of research and point out experimental approaches that promise to contribute to a spatiomechanistic understanding of MCS functions.
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Affiliation(s)
- Patrick C Hoffmann
- Cell Biology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Wanda Kukulski
- Cell Biology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
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30
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The Role of Mitochondria in the Activation/Maintenance of SOCE: Membrane Contact Sites as Signaling Hubs Sustaining Store-Operated Ca2+ Entry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:277-296. [DOI: 10.1007/978-3-319-57732-6_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
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31
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Kornmann B, Ungermann C. Membrane contact sites. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017. [DOI: 10.1016/j.bbamcr.2017.06.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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32
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Dutta D, Hickey K, Salifu M, Fauer C, Willingham C, Stabenfeldt SE. Spatiotemporal presentation of exogenous SDF-1 with PLGA nanoparticles modulates SDF-1/CXCR4 signaling axis in the rodent cortex. Biomater Sci 2017; 5:1640-1651. [PMID: 28703822 PMCID: PMC5588897 DOI: 10.1039/c7bm00489c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Stromal cell-derived factor-1 (SDF-1) and its key receptor CXCR4 have been implicated in directing cellular recruitment for several pathological/disease conditions thus also gained considerable attention for regenerative medicine. One regenerative approach includes sustained release of SDF-1 to stimulate prolonged stem cell recruitment. However, the impact of SDF-1 sustained release on the endogenous SDF-1/CXCR4 signaling axis is largely unknown as auto-regulatory mechanisms typically dictate cytokine/receptor signaling. We hypothesize that spatiotemporal presentation of exogenous SDF-1 is a key factor in achieving long-term manipulation of endogenous SDF-1/CXCR4 signaling. Here in the present study, we sought to probe our hypothesis using a transgenic mouse model to contrast the spatial activation of endogenous SDF-1 and CXCR4 in response to exogenous SDF-1 injected in bolus or controlled release (PLGA nanoparticles) form in the adult rodent cortex. Our data suggests that the manner of SDF-1 presentation significantly affected initial CXCR4 cellular activation/recruitment despite having similar protein payloads over the first 24 h (∼30 ng for both bolus and sustained release groups). Yet, one week post-injection, this response was negligible. Therefore, the transient nature CXCR4 recruitment/activation in response to bolus or controlled release SDF-1 indicated that cytokine/receptor auto-regulatory mechanisms may demand more complex release profiles (i.e. delayed and/or pulsed release) to achieve sustained cellular response.
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Affiliation(s)
- D Dutta
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA.
| | - K Hickey
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA.
| | - M Salifu
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA.
| | - C Fauer
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA.
| | - C Willingham
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA.
| | - S E Stabenfeldt
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA.
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33
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Wong LH, Levine TP. Tubular lipid binding proteins (TULIPs) growing everywhere. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1439-1449. [PMID: 28554774 PMCID: PMC5507252 DOI: 10.1016/j.bbamcr.2017.05.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/11/2017] [Accepted: 05/17/2017] [Indexed: 12/27/2022]
Abstract
Tubular lipid binding proteins (TULIPs) have become a focus of interest in the cell biology of lipid signalling, lipid traffic and membrane contact sites. Each tubular domain has an internal pocket with a hydrophobic lining that can bind a hydrophobic molecule such as a lipid. This allows TULIP proteins to carry lipids through the aqueous phase. TULIP domains were first found in a large family of extracellular proteins related to the bacterial permeability-inducing protein (BPI) and cholesterol ester transfer protein (CETP). Since then, the same fold and lipid transfer capacity have been found in SMP domains (so-called for their occurrence in synaptotagmin, mitochondrial and lipid binding proteins), which localise to intracellular membrane contact sites. Here the methods for identifying known TULIPs are described, and used to find previously unreported TULIPs, one in the silk polymer and another in prokaryotes illustrated by the E. coli protein YceB. The bacterial TULIP alters views on the likely evolution of the domain, suggesting its presence in the last universal common ancestor. The major function of TULIPs is to handle lipids, but we still do not know how they work in detail, or how many more remain to be discovered. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann. Proteins with the tubular lipid binding fold exist in a wider variety than is usually appreciated. TULIPs are found in prokaryotes, altering views on their evolution. It is not yet known whether TULIPs transfer lipids as tunnels or as shuttles. Tests have not yet been done to say if TULIPs with SMP domains (for example E-syts and ERMES components) tether contact sites. It is likely that more TULIPs remain to be discovered.
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Affiliation(s)
- Louise H Wong
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Tim P Levine
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK.
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34
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Chang CL, Chen YJ, Liou J. ER-plasma membrane junctions: Why and how do we study them? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1494-1506. [PMID: 28554772 DOI: 10.1016/j.bbamcr.2017.05.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/09/2017] [Accepted: 05/17/2017] [Indexed: 12/17/2022]
Abstract
Endoplasmic reticulum (ER)-plasma membrane (PM) junctions are membrane microdomains important for communication between the ER and the PM. ER-PM junctions were first reported in muscle cells in 1957, but mostly ignored in non-excitable cells due to their scarcity and lack of functional significance. In 2005, the discovery of stromal interaction molecule 1 (STIM1) mediating a universal Ca2+ feedback mechanism at ER-PM junctions in mammalian cells led to a resurgence of research interests toward ER-PM junctions. In the past decade, several major advancements have been made in this emerging topic in cell biology, including the generation of tools for labeling ER-PM junctions and the unraveling of mechanisms underlying regulation and functions of ER-PM junctions. This review summarizes early studies, recently developed tools, and current advances in the characterization and understanding of ER-PM junctions. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann.
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Affiliation(s)
- Chi-Lun Chang
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yu-Ju Chen
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jen Liou
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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35
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Aufschnaiter A, Kohler V, Diessl J, Peselj C, Carmona-Gutierrez D, Keller W, Büttner S. Mitochondrial lipids in neurodegeneration. Cell Tissue Res 2017; 367:125-140. [PMID: 27449929 PMCID: PMC5203858 DOI: 10.1007/s00441-016-2463-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 06/24/2016] [Indexed: 01/10/2023]
Abstract
Mitochondrial dysfunction is a common feature of many neurodegenerative diseases, including proteinopathies such as Alzheimer's or Parkinson's disease, which are characterized by the deposition of aggregated proteins in the form of insoluble fibrils or plaques. The distinct molecular processes that eventually result in mitochondrial dysfunction during neurodegeneration are well studied but still not fully understood. However, defects in mitochondrial fission and fusion, mitophagy, oxidative phosphorylation and mitochondrial bioenergetics have been linked to cellular demise. These processes are influenced by the lipid environment within mitochondrial membranes as, besides membrane structure and curvature, recruitment and activity of different proteins also largely depend on the respective lipid composition. Hence, the interaction of neurotoxic proteins with certain lipids and the modification of lipid composition in different cell compartments, in particular mitochondria, decisively impact cell death associated with neurodegeneration. Here, we discuss the relevance of mitochondrial lipids in the pathological alterations that result in neuronal demise, focussing on proteinopathies.
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Affiliation(s)
- Andreas Aufschnaiter
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria
| | - Verena Kohler
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria
| | - Jutta Diessl
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Carlotta Peselj
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Didac Carmona-Gutierrez
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria
| | - Walter Keller
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria
| | - Sabrina Büttner
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria.
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden.
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36
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Lipid transfer proteins do their thing anchored at membrane contact sites… but what is their thing? Biochem Soc Trans 2016; 44:517-27. [PMID: 27068964 DOI: 10.1042/bst20150275] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Indexed: 02/06/2023]
Abstract
Membrane contact sites are structures where two organelles come close together to regulate flow of material and information between them. One type of inter-organelle communication is lipid exchange, which must occur for membrane maintenance and in response to environmental and cellular stimuli. Soluble lipid transfer proteins have been extensively studied, but additional families of transfer proteins have been identified that are anchored into membranes by transmembrane helices so that they cannot diffuse through the cytosol to deliver lipids. If such proteins target membrane contact sites they may be major players in lipid metabolism. The eukaryotic family of so-called Lipid transfer proteins Anchored at Membrane contact sites (LAMs) all contain both a sterol-specific lipid transfer domain in the StARkin superfamily (related to StART/Bet_v1), and one or more transmembrane helices anchoring them in the endoplasmic reticulum (ER), making them interesting subjects for study in relation to sterol metabolism. They target a variety of membrane contact sites, including newly described contacts between organelles that were already known to make contact by other means. Lam1-4p target punctate ER-plasma membrane contacts. Lam5p and Lam6p target multiple contacts including a new category: vacuolar non-NVJ cytoplasmic ER (VancE) contacts. These developments confirm previous observations on tubular lipid-binding proteins (TULIPs) that established the importance of membrane anchored proteins for lipid traffic. However, the question remaining to be solved is the most difficult of all: are LAMs transporters, or alternately are they regulators that affect traffic more indirectly?
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37
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Dimmer KS, Rapaport D. Mitochondrial contact sites as platforms for phospholipid exchange. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:69-80. [PMID: 27477677 DOI: 10.1016/j.bbalip.2016.07.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 07/21/2016] [Accepted: 07/22/2016] [Indexed: 12/15/2022]
Abstract
Mitochondria are unique organelles that contain their own - although strongly reduced - genome, and are surrounded by two membranes. While most cellular phospholipid biosynthesis takes place in the ER, mitochondria harbor the whole spectrum of glycerophospholipids common to biological membranes. Mitochondria also contribute to overall phospholipid biosynthesis in cells by producing phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin. Considering these features, it is not surprising that mitochondria maintain highly active exchange of phospholipids with other cellular compartments. In this contribution we describe the transport of phospholipids between mitochondria and other organelles, and discuss recent developments in our understanding of the molecular functions of the protein complexes that mediate these processes. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.
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Affiliation(s)
- Kai Stefan Dimmer
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany.
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
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38
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Gallo A, Vannier C, Galli T. Endoplasmic Reticulum-Plasma Membrane Associations:Structures and Functions. Annu Rev Cell Dev Biol 2016; 32:279-301. [PMID: 27298092 DOI: 10.1146/annurev-cellbio-111315-125024] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Inside eukaryotic cells, membrane contact sites (MCSs), regions where two membrane-bound organelles are apposed at less than 30 nm, generate regions of important lipid and calcium exchange. This review principally focuses on the structure and the function of MCSs between the endoplasmic reticulum (ER) and the plasma membrane (PM). Here we describe how tethering structures form and maintain these junctions and, in some instances, participate in their function. We then discuss recent insights into the mechanisms by which specific classes of proteins mediate nonvesicular lipid exchange between the ER and PM and how such phenomena, already known to be crucial for maintaining organelle identity, are also emerging as regulators of cell growth and development.
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Affiliation(s)
- Alessandra Gallo
- Membrane Traffic in Health & Disease Group (INSERM ERL U950), F-75013 Paris, France;
| | - Christian Vannier
- Membrane Traffic in Health & Disease Group (INSERM ERL U950), F-75013 Paris, France;
| | - Thierry Galli
- Membrane Traffic in Health & Disease Group (INSERM ERL U950), F-75013 Paris, France;
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39
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Extended synaptotagmins are Ca2+-dependent lipid transfer proteins at membrane contact sites. Proc Natl Acad Sci U S A 2016; 113:4362-7. [PMID: 27044075 DOI: 10.1073/pnas.1517259113] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Organelles are in constant communication with each other through exchange of proteins (mediated by trafficking vesicles) and lipids [mediated by both trafficking vesicles and lipid transfer proteins (LTPs)]. It has long been known that vesicle trafficking can be tightly regulated by the second messenger Ca(2+), allowing membrane protein transport to be adjusted according to physiological demands. However, it remains unclear whether LTP-mediated lipid transport can also be regulated by Ca(2+) In this work, we show that extended synaptotagmins (E-Syts), poorly understood membrane proteins at endoplasmic reticulum-plasma membrane contact sites, are Ca(2+)-dependent LTPs. Using both recombinant and endogenous mammalian proteins, we discovered that E-Syts transfer glycerophospholipids between membrane bilayers in the presence of Ca(2+) E-Syts use their lipid-accommodating synaptotagmin-like mitochondrial lipid binding protein (SMP) domains to transfer lipids. However, the SMP domains themselves cannot transport lipids unless the two membranes are tightly tethered by Ca(2+)-bound C2 domains. Strikingly, the Ca(2+)-regulated lipid transfer activity of E-Syts was fully recapitulated when the SMP domain was fused to the cytosolic domain of synaptotagmin-1, the Ca(2+)sensor in synaptic vesicle fusion, indicating that a common mechanism of membrane tethering governs the Ca(2+)regulation of lipid transfer and vesicle fusion. Finally, we showed that microsomal vesicles isolated from mammalian cells contained robust Ca(2+)-dependent lipid transfer activities, which were mediated by E-Syts. These findings established E-Syts as a novel class of LTPs and showed that LTP-mediated lipid trafficking, like vesicular transport, can be subject to tight Ca(2+)regulation.
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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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41
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Extended-Synaptotagmins (E-Syts); the extended story. Pharmacol Res 2016; 107:48-56. [PMID: 26926095 DOI: 10.1016/j.phrs.2016.01.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 01/24/2016] [Accepted: 01/24/2016] [Indexed: 12/29/2022]
Abstract
The Extended-Synaptotagmin (E-Syt) membrane proteins were only recently discovered, but have already been implicated in a range of interrelated cellular functions, including calcium and receptor signaling, and membrane lipid transport. However, despite their evolutionary conservation and detailed studies of their molecular actions, we still have little idea of how and when these proteins are required in cellular and organism physiology. Here we review our present understanding of the E-Syts and discuss the molecular functions and in vivo requirements for these proteins.
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Lipid transfer and metabolism across the endolysosomal-mitochondrial boundary. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:880-894. [PMID: 26852832 DOI: 10.1016/j.bbalip.2016.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 01/30/2016] [Accepted: 02/03/2016] [Indexed: 01/10/2023]
Abstract
Lysosomes and mitochondria occupy a central stage in the maintenance of cellular homeostasis, by playing complementary roles in nutrient sensing and energy metabolism. Specifically, these organelles function as signaling hubs that integrate environmental and endogenous stimuli with specific metabolic responses. In particular, they control various lipid biosynthetic and degradative pipelines, either directly or indirectly, by regulating major cellular metabolic pathways, and by physical and functional connections established with each other and with other organelles. Membrane contact sites allow the exchange of ions and molecules between organelles, even without membrane fusion, and are privileged routes for lipid transfer among different membrane compartments. These inter-organellar connections typically involve the endoplasmic reticulum. Direct membrane contacts have now been described also between lysosomes, autophagosomes, lipid droplets, and mitochondria. This review focuses on these recently identified membrane contact sites, and on their role in lipid biosynthesis, exchange, turnover and catabolism. 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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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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Reinisch KM, De Camilli P. SMP-domain proteins at membrane contact sites: Structure and function. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:924-927. [PMID: 26686281 DOI: 10.1016/j.bbalip.2015.12.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 12/01/2015] [Accepted: 12/07/2015] [Indexed: 01/28/2023]
Abstract
SMP-domains are found in proteins that localize to membrane contact sites. Elucidation of the properties of these proteins gives clues as to the molecular bases underlying processes that occur at such sites. Described here are recent discoveries concerning the structure, function, and regulation of the Extended-Synaptotagmin proteins and ERMES complex subunits, SMP-domain proteins at endoplasmic reticulum (ER)-plasma membrane and ER-mitochondrial contacts, respectively. They act as tethers contributing to the architecture of these sites and as lipid transporters that convey glycerolipids between apposed membranes. 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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Affiliation(s)
- Karin M Reinisch
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
| | - Pietro De Camilli
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Neurobiology, Howard Hughes Medical Institute, Kavli Institute for Neuroscience and Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT 06510, USA.
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Herdman C, Tremblay MG, Mishra PK, Moss T. Loss of Extended Synaptotagmins ESyt2 and ESyt3 does not affect mouse development or viability, but in vitro cell migration and survival under stress are affected. Cell Cycle 2015; 13:2616-25. [PMID: 25486202 PMCID: PMC4614831 DOI: 10.4161/15384101.2014.943573] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Extended Synaptotagmins (Esyts) are a family of multi-C2 domain membrane proteins with orthologs in organisms from yeast to human. Three Esyt genes exist in mouse and human and these have most recently been implicated in the formation of junctions between endoplasmic reticulum and plasma membrane, as well as the Ca2+ dependent replenishment of membrane phospholipids. The data are consistent with a function in extracellular signal transduction and cell adhesion, and indeed Esyt2 was previously implicated in both these functions in Xenopus. Despite this, little is known of the function of the Esyts in vivo. We have generated mouse lines carrying homozygous deletions in one or both of the genes encoding the highly homologous Esyt2 and Esyt3 proteins. Surprisingly, esyt2−/−/esyt3−/− mice develop normally and are both viable and fertile. In contrast, esyt2−/−/esyt3−/− mouse embryonic fibroblasts display a reduced ability to migrate in standard in vitro assays, and are less resistant to stringent culture conditions and to oxidative stress than equivalent wild type fibroblasts.
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Affiliation(s)
- Chelsea Herdman
- a Laboratory of Growth and Development; St-Patrick Research Group in Basic Oncology ; Cancer Division of the Quebec University Hospital Research Centre ; Québec , QC , Canada
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46
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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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Tremblay MG, Herdman C, Guillou F, Mishra PK, Baril J, Bellenfant S, Moss T. Extended Synaptotagmin Interaction with the Fibroblast Growth Factor Receptor Depends on Receptor Conformation, Not Catalytic Activity. J Biol Chem 2015; 290:16142-56. [PMID: 25922075 DOI: 10.1074/jbc.m115.656918] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Indexed: 11/06/2022] Open
Abstract
We previously demonstrated that ESyt2 interacts specifically with the activated FGF receptor and is required for a rapid phase of receptor internalization and for functional signaling via the ERK pathway in early Xenopus embryos. ESyt2 is one of the three-member family of Extended Synaptotagmins that were recently shown to be implicated in the formation of endoplasmic reticulum (ER)-plasma membrane (PM) junctions and in the Ca(2+) dependent regulation of these junctions. Here we show that ESyt2 is directed to the ER by its putative transmembrane domain, that the ESyts hetero- and homodimerize, and that ESyt2 homodimerization in vivo requires a TM adjacent sequence but not the SMP domain. ESyt2 and ESyt3, but not ESyt1, selectively interact in vivo with activated FGFR1. In the case of ESyt2, this interaction requires a short TM adjacent sequence and is independent of receptor autophosphorylation, but dependent on receptor conformation. The data show that ESyt2 recognizes a site in the upper kinase lobe of FGFR1 that is revealed by displacement of the kinase domain activation loop during receptor activation.
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Affiliation(s)
- Michel G Tremblay
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Chelsea Herdman
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - François Guillou
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Prakash K Mishra
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Joëlle Baril
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Sabrina Bellenfant
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Tom Moss
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
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Lang A, John Peter AT, Kornmann B. ER-mitochondria contact sites in yeast: beyond the myths of ERMES. Curr Opin Cell Biol 2015; 35:7-12. [PMID: 25836730 DOI: 10.1016/j.ceb.2015.03.002] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 03/10/2015] [Accepted: 03/10/2015] [Indexed: 10/23/2022]
Abstract
A standout feature of eukaryotic cells is the presence of organelles with distinct chemical compositions and physical properties, which aid in the accomplishment of specialized metabolic tasks. This complex topology, however, makes a permanent crosstalk between the organelles a necessity for the coordination of cellular function. While molecule exchange between organelles via the vesicular transport system has been extensively studied, communication via direct connections has only recently become a new matter of interest. These direct connections termed membrane contact sites (MCSs) represent zones of close proximity (10-30nm) between two organelles. Research in the past years has revealed a number of MCSs especially between the ER and almost every other organelle [1(•)]. In particular, the MCSs between the ER and the mitochondria have undergone intense investigation. While the quest for ER-mitochondria MCS components in human cells has led to the revelation of an ever growing number of potential factors, studies in the simpler eukaryote Saccharomyces cerevisiae revealed the actual existence of a molecular tether between the two organelles [2(••)].
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Affiliation(s)
- Alexander Lang
- Institute of Biochemistry, ETH Zurich, 8093 Zürich, Switzerland
| | | | - Benoît Kornmann
- Institute of Biochemistry, ETH Zurich, 8093 Zürich, Switzerland.
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Penny CJ, Kilpatrick BS, Eden ER, Patel S. Coupling acidic organelles with the ER through Ca²⁺ microdomains at membrane contact sites. Cell Calcium 2015; 58:387-96. [PMID: 25866010 DOI: 10.1016/j.ceca.2015.03.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 03/13/2015] [Accepted: 03/14/2015] [Indexed: 10/23/2022]
Abstract
Acidic organelles such as lysosomes serve as non-canonical Ca(2+) stores. The Ca(2+) mobilising messenger NAADP is thought to trigger local Ca(2+) release from such stores. These events are then amplified by Ca(2+) channels on canonical ER Ca(2+) stores to generate physiologically relevant global Ca(2+) signals. Coupling likely occurs at microdomains formed at membrane contact sites between acidic organelles and the ER. Molecular analyses and computational modelling suggest heterogeneity in the composition of these contacts and predicted Ca(2+) microdomain behaviour. Conversely, acidic organelles might also locally amplify and temper ER-evoked Ca(2+) signals. Ca(2+) microdomains between distinct Ca(2+) stores are thus likely to be integral to the genesis of complex Ca(2+) signals.
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Affiliation(s)
- Christopher J Penny
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Bethan S Kilpatrick
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Emily R Eden
- Department of Cell Biology, Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK.
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50
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Apical localization of inositol 1,4,5-trisphosphate receptors is independent of extended synaptotagmins in hepatocytes. PLoS One 2014; 9:e114043. [PMID: 25437447 PMCID: PMC4250053 DOI: 10.1371/journal.pone.0114043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 11/03/2014] [Indexed: 12/12/2022] Open
Abstract
Extended synaptotagmins (E-Syts) are a recently identified family of proteins that tether the endoplasmic reticulum (ER) to the plasma membrane (PM) in part by conferring regulation of cytosolic calcium (Ca2+) at these contact sites (Cell, 2013). However, the mechanism by which E-Syts link this tethering to Ca2+ signaling is unknown. Ca2+ waves in polarized epithelia are initiated by inositol 1,4,5-trisphosphate receptors (InsP3Rs), and these waves begin in the apical region because InsP3Rs are targeted to the ER adjacent to the apical membrane. In this study we investigated whether E-Syts are responsible for this targeting. Primary rat hepatocytes were used as a model system, because a single InsP3R isoform (InsP3R-II) is tethered to the peri-apical ER in these cells. Additionally, it has been established in hepatocytes that the apical localization of InsP3Rs is responsible for Ca2+ waves and secretion and is disrupted in disease states in which secretion is impaired. We found that rat hepatocytes express two of the three identified E-Syts (E-Syt1 and E-Syt2). Individual or simultaneous siRNA knockdown of these proteins did not alter InsP3R-II expression levels, apical localization or average InsP3R-II cluster size. Moreover, apical secretion of the organic anion 5-chloromethylfluorescein diacetate (CMFDA) was not changed in cells lacking E-Syts but was reduced in cells in which cytosolic Ca2+ was buffered. These data provide evidence that E-Syts do not participate in the targeting of InsP3Rs to the apical region. Identifying tethers that bring InsP3Rs to the apical region remains an important question, since mis-targeting of InsP3Rs leads to impaired secretory activity.
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