151
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Deardorff AS, Romer SH, Fyffe RE. Location, location, location: the organization and roles of potassium channels in mammalian motoneurons. J Physiol 2021; 599:1391-1420. [DOI: 10.1113/jp278675] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 01/08/2021] [Indexed: 11/08/2022] Open
Affiliation(s)
- Adam S. Deardorff
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
- Department of Neurology and Internal Medicine, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
| | - Shannon H. Romer
- Odyssey Systems Environmental Health Effects Laboratory, Navy Medical Research Unit‐Dayton Wright‐Patterson Air Force Base OH 45433 USA
| | - Robert E.W. Fyffe
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
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152
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Fakhree MAA, Konings IBM, Kole J, Cambi A, Blum C, Claessens MMAE. The Localization of Alpha-synuclein in the Endocytic Pathway. Neuroscience 2021; 457:186-195. [PMID: 33482328 DOI: 10.1016/j.neuroscience.2021.01.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 01/11/2021] [Accepted: 01/11/2021] [Indexed: 01/24/2023]
Abstract
Alpha-synuclein (αS) is an intrinsically disordered protein (IDP) that is abundantly present in the brain and is associated with Parkinson's disease (PD). In spite of its abundance and its contribution to PD pathogenesis, the exact cellular function of αS remains largely unknown. The ability of αS to remodel phospholipid model membranes combined with biochemical and cellular studies suggests that αS is involved in endocytosis. To unravel with which route(s) and stage(s) of the endocytic pathway αS is associated, we quantified the colocalization between αS and endocytic marker proteins in differentiated SH-SY5Y neuronal cells, using an object based colocalization analysis. Comparison with randomized data allowed us to discriminate between structural and coincidental colocalizations. A large fraction of the αS positive vesicles colocalizes with caveolin positive vesicles, a smaller fraction colocalizes with EEA1 and Rab7. We find no structural colocalization between αS and clathrin and Rab11 positive vesicles. We conclude that in a physiological context, αS is structurally associated with caveolin dependent membrane vesiculation and is found further along the endocytic pathway, in decreasing amounts, on early and late endosomes. Our results not only shed new light on the function of αS, they also provide a possible link between αS function and vesicle trafficking malfunction in PD.
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Affiliation(s)
- Mohammad A A Fakhree
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Irene B M Konings
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Jeroen Kole
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Alessandra Cambi
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, The Netherlands
| | - Christian Blum
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Mireille M A E Claessens
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
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153
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Cichoń MA, Klas K, Buchberger M, Hammer M, Seré K, Zenke M, Tschachler E, Elbe-Bürger A. Distinct Distribution of RTN1A in Immune Cells in Mouse Skin and Lymphoid Organs. Front Cell Dev Biol 2021; 8:608876. [PMID: 33542915 PMCID: PMC7853085 DOI: 10.3389/fcell.2020.608876] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/27/2020] [Indexed: 11/13/2022] Open
Abstract
The endoplasmic reticulum-associated protein reticulon 1A (RTN1A) is primarily expressed in neuronal tissues but was recently identified also specifically in cells of the dendritic cell (DC) lineage, including epidermal Langerhans cells (LCs) and dermal DCs in human skin. In this study, we found that in mice major histocompatibility complex class II (MHCII)+CD207+ LCs but not dermal DCs express RTN1A. Further, RTN1A expression was identified in CD45+MHCII+CD207+ cells of the lymph node and spleen but not in the thymus. Of note, RTN1A was expressed in CD207low LCs in adult skin as well as emigrated LCs and DCs in lymph nodes and marginally in CD207hi cells. Ontogeny studies revealed that RTN1A expression occurred before the appearance of the LC markers MHCII and CD207 in LC precursors, while dermal DC and T cell precursors remained negative during skin development. Analogous to the expression of RTN1A in neural tissue, we identified expression of RTN1A in skin nerves. Immunostaining revealed co-localization of RTN1A with nerve neurofilaments only in fetal but not in newborn or adult dermis. Our findings suggest that RTN1A might be involved in the LC differentiation process given its early expression in LC precursors and stable expression onward. Further analysis of the RTN1A expression pattern will enable the elucidation of the functional roles of RTN1A in both the immune and the nervous system of the skin.
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Affiliation(s)
| | - Katharina Klas
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Maria Buchberger
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Martina Hammer
- Institute of Cancer Research, Medical University of Vienna, Vienna, Austria
| | - Kristin Seré
- Department of Cell Biology, Institute for Biomedical Engineering, RWTH Aachen University Medical School, Aachen, Germany.,Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Martin Zenke
- Department of Cell Biology, Institute for Biomedical Engineering, RWTH Aachen University Medical School, Aachen, Germany.,Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Erwin Tschachler
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
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154
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Bagalkot TR, Block ER, Bucchin K, Balcita-Pedicino JJ, Calderon M, Sesack SR, Sorkin A. Dopamine Transporter Localization in Medial Forebrain Bundle Axons Indicates Its Long-Range Transport Primarily by Membrane Diffusion with a Limited Contribution of Vesicular Traffic on Retromer-Positive Compartments. J Neurosci 2021; 41:234-250. [PMID: 33234607 PMCID: PMC7810657 DOI: 10.1523/jneurosci.0744-20.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 11/05/2020] [Accepted: 11/13/2020] [Indexed: 12/18/2022] Open
Abstract
Dopamine transporter (DAT) controls dopamine neurotransmission by clearing synaptically released dopamine. However, trafficking itineraries of DAT, which determine its cell-surface concentration near synapses, are poorly characterized. It is especially unknown how DAT is transported between spatially distant midbrain somatodendritic and striatal axonal compartments. To examine this "long-range" trafficking, the localization and membrane diffusion of HA-epitope tagged DAT in the medial forebrain bundle (MFB) of a knock-in mouse (both sexes) were analyzed using confocal, super-resolution and EM in intact brain and acute brain slices. HA-DAT was abundant in the plasma membrane of MFB axons, similar to the striatum, although the intracellular fraction of HA-DAT in MFB was more substantial. Intracellular HA-DAT colocalized with VPS35, a subunit of the retromer complex mediating recycling from endosomes, in a subset of axons. Late endosomes, lysosomes, and endoplasmic reticulum were abundant in the soma but minimally present in MFB axons, suggesting that biosynthesis and lysosomal degradation of DAT are confined to soma. Together, the data suggest that membrane diffusion is the main mode of long-range DAT transport through MFB, although the contribution of vesicular traffic can be significant in a population of MFB axons. Based on HA-DAT diffusion rates, plasma membrane DAT in MFB axons turns over with a halftime of ∼20 d, which explains the extremely slow turnover of DAT protein in the brain. Unexpectedly, the mean diameter of DAT-labeled MFB axons was observed to be twice larger than reported for striatum. The implications of this finding for dopamine neuron physiology are discussed.SIGNIFICANCE STATEMENT The dopamine transporter (DAT) is a key regulator of dopamine neurotransmission and a target of abused psychostimulants. In the present study, we examined, for the first time, mechanisms of the long-range traffic of DAT in intact brain and acute brain slices from the knock-in mouse expressing epitope-tagged DAT. Using a combination of confocal, super-resolution and EM, we defined DAT localization and its membrane diffusion parameters in medial forebrain bundle axonal tracts connecting midbrain somatodendritic and striatal axonal compartments of dopaminergic neurons. In contrast to the widely accepted model of long-range axonal transport, our studies suggest that DAT traffics between midbrain and striatum, mainly by lateral diffusion in the plasma membrane with only a limited contribution of vesicular transport in recycling endosomes.
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Affiliation(s)
- Tarique R Bagalkot
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Ethan R Block
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
- Chatham University, Pittsburgh, Pennsylvania 15232
| | - Kristen Bucchin
- Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Judith Joyce Balcita-Pedicino
- Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Michael Calderon
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Susan R Sesack
- Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Alexander Sorkin
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
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155
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TSUBOI M, HIRABAYASHI Y. New insights into the regulation of synaptic transmission and plasticity by the endoplasmic reticulum and its membrane contacts. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2021; 97:559-572. [PMID: 34897182 PMCID: PMC8687855 DOI: 10.2183/pjab.97.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 10/18/2021] [Indexed: 06/14/2023]
Abstract
Mammalian neurons are highly compartmentalized yet very large cells. To provide each compartment with its distinct properties, metabolic homeostasis and molecular composition need to be precisely coordinated in a compartment-specific manner. Despite the importance of the endoplasmic reticulum (ER) as a platform for various biochemical reactions, such as protein synthesis, protein trafficking, and intracellular calcium control, the contribution of the ER to neuronal compartment-specific functions and plasticity remains elusive. Recent advances in the development of live imaging and serial scanning electron microscopy (sSEM) analysis have revealed that the neuronal ER is a highly dynamic organelle with compartment-specific structures. sSEM studies also revealed that the ER forms contacts with other membranes, such as the mitochondria and plasma membrane, although little is known about the functions of these ER-membrane contacts. In this review, we discuss the mechanisms and physiological roles of the ER structure and ER-mitochondria contacts in synaptic transmission and plasticity, thereby highlighting a potential link between organelle ultrastructure and neuronal functions.
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Affiliation(s)
- Masafumi TSUBOI
- Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
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156
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Serwach K, Gruszczynska-Biegala J. Target Molecules of STIM Proteins in the Central Nervous System. Front Mol Neurosci 2020; 13:617422. [PMID: 33424550 PMCID: PMC7786003 DOI: 10.3389/fnmol.2020.617422] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/02/2020] [Indexed: 12/16/2022] Open
Abstract
Stromal interaction molecules (STIMs), including STIM1 and STIM2, are single-pass transmembrane proteins that are located predominantly in the endoplasmic reticulum (ER). They serve as calcium ion (Ca2+) sensors within the ER. In the central nervous system (CNS), they are involved mainly in Orai-mediated store-operated Ca2+ entry (SOCE). The key molecular components of the SOCE pathway are well-characterized, but the molecular mechanisms that underlie the regulation of this pathway need further investigation. Numerous intracellular target proteins that are located in the plasma membrane, ER, cytoskeleton, and cytoplasm have been reported to play essential roles in concert with STIMs, such as conformational changes in STIMs, their translocation, the stabilization of their interactions with Orai, and the activation of other channels. The present review focuses on numerous regulators, such as Homer, SOCE-associated regulatory factor (SARAF), septin, synaptopodin, golli proteins, partner of STIM1 (POST), and transcription factors and proteasome inhibitors that regulate STIM-Orai interactions in the CNS. Further we describe novel roles of STIMs in mediating Ca2+ influx via other than Orai pathways, including TRPC channels, VGCCs, AMPA and NMDA receptors, and group I metabotropic glutamate receptors. This review also summarizes recent findings on additional molecular targets of STIM proteins including SERCA, IP3Rs, end-binding proteins (EB), presenilin, and CaMKII. Dysregulation of the SOCE-associated toolkit, including STIMs, contributes to the development of neurodegenerative disorders (e.g., Alzheimer's disease, Parkinson's disease, and Huntington's disease), traumatic brain injury, epilepsy, and stroke. Emerging evidence points to the role of STIM proteins and several of their molecular effectors and regulators in neuronal and glial physiology and pathology, suggesting their potential application for future therapeutic strategies.
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Affiliation(s)
- Karolina Serwach
- Molecular Biology Unit, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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157
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Koppers M, Özkan N, Farías GG. Complex Interactions Between Membrane-Bound Organelles, Biomolecular Condensates and the Cytoskeleton. Front Cell Dev Biol 2020; 8:618733. [PMID: 33409284 PMCID: PMC7779554 DOI: 10.3389/fcell.2020.618733] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 12/03/2020] [Indexed: 12/13/2022] Open
Abstract
Membrane-bound and membraneless organelles/biomolecular condensates ensure compartmentalization into functionally distinct units enabling proper organization of cellular processes. Membrane-bound organelles form dynamic contacts with each other to enable the exchange of molecules and to regulate organelle division and positioning in coordination with the cytoskeleton. Crosstalk between the cytoskeleton and dynamic membrane-bound organelles has more recently also been found to regulate cytoskeletal organization. Interestingly, recent work has revealed that, in addition, the cytoskeleton and membrane-bound organelles interact with cytoplasmic biomolecular condensates. The extent and relevance of these complex interactions are just beginning to emerge but may be important for cytoskeletal organization and organelle transport and remodeling. In this review, we highlight these emerging functions and emphasize the complex interplay of the cytoskeleton with these organelles. The crosstalk between membrane-bound organelles, biomolecular condensates and the cytoskeleton in highly polarized cells such as neurons could play essential roles in neuronal development, function and maintenance.
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Affiliation(s)
| | | | - Ginny G. Farías
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
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158
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Andres-Alonso M, Kreutz MR, Karpova A. Autophagy and the endolysosomal system in presynaptic function. Cell Mol Life Sci 2020; 78:2621-2639. [PMID: 33340068 PMCID: PMC8004491 DOI: 10.1007/s00018-020-03722-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 11/17/2020] [Accepted: 11/24/2020] [Indexed: 12/11/2022]
Abstract
The complex morphology of neurons, the specific requirements of synaptic neurotransmission and the accompanying metabolic demands create a unique challenge for proteostasis. The main machineries for neuronal protein synthesis and degradation are localized in the soma, while synaptic junctions are found at vast distances from the cell body. Sophisticated mechanisms must, therefore, ensure efficient delivery of newly synthesized proteins and removal of faulty proteins. These requirements are exacerbated at presynaptic sites, where the demands for protein turnover are especially high due to synaptic vesicle release and recycling that induces protein damage in an intricate molecular machinery, and where replacement of material is hampered by the extreme length of the axon. In this review, we will discuss the contribution of the two major pathways in place, autophagy and the endolysosomal system, to presynaptic protein turnover and presynaptic function. Although clearly different in their biogenesis, both pathways are characterized by cargo collection and transport into distinct membrane-bound organelles that eventually fuse with lysosomes for cargo degradation. We summarize the available evidence with regard to their degradative function, their regulation by presynaptic machinery and the cargo for each pathway. Finally, we will discuss the interplay of both pathways in neurons and very recent findings that suggest non-canonical functions of degradative organelles in synaptic signalling and plasticity.
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Affiliation(s)
- Maria Andres-Alonso
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany
- Leibniz Group 'Dendritic Organelles and Synaptic Function', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Michael R Kreutz
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany.
- Leibniz Group 'Dendritic Organelles and Synaptic Function', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany.
- Center for Behavioral Brain Sciences, Otto Von Guericke University, Magdeburg, Germany.
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany.
| | - Anna Karpova
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany.
- Center for Behavioral Brain Sciences, Otto Von Guericke University, Magdeburg, Germany.
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159
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Ca 2+ Dyshomeostasis Disrupts Neuronal and Synaptic Function in Alzheimer's Disease. Cells 2020; 9:cells9122655. [PMID: 33321866 PMCID: PMC7763805 DOI: 10.3390/cells9122655] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/02/2020] [Accepted: 12/07/2020] [Indexed: 02/07/2023] Open
Abstract
Ca2+ homeostasis is essential for multiple neuronal functions and thus, Ca2+ dyshomeostasis can lead to widespread impairment of cellular and synaptic signaling, subsequently contributing to dementia and Alzheimer's disease (AD). While numerous studies implicate Ca2+ mishandling in AD, the cellular basis for loss of cognitive function remains under investigation. The process of synaptic degradation and degeneration in AD is slow, and constitutes a series of maladaptive processes each contributing to a further destabilization of the Ca2+ homeostatic machinery. Ca2+ homeostasis involves precise maintenance of cytosolic Ca2+ levels, despite extracellular influx via multiple synaptic Ca2+ channels, and intracellular release via organelles such as the endoplasmic reticulum (ER) via ryanodine receptor (RyRs) and IP3R, lysosomes via transient receptor potential mucolipin channel (TRPML) and two pore channel (TPC), and mitochondria via the permeability transition pore (PTP). Furthermore, functioning of these organelles relies upon regulated inter-organelle Ca2+ handling, with aberrant signaling resulting in synaptic dysfunction, protein mishandling, oxidative stress and defective bioenergetics, among other consequences consistent with AD. With few effective treatments currently available to mitigate AD, the past few years have seen a significant increase in the study of synaptic and cellular mechanisms as drivers of AD, including Ca2+ dyshomeostasis. Here, we detail some key findings and discuss implications for future AD treatments.
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160
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Lu M, van Tartwijk FW, Lin JQ, Nijenhuis W, Parutto P, Fantham M, Christensen CN, Avezov E, Holt CE, Tunnacliffe A, Holcman D, Kapitein L, Schierle GSK, Kaminski CF. The structure and global distribution of the endoplasmic reticulum network are actively regulated by lysosomes. SCIENCE ADVANCES 2020; 6:eabc7209. [PMID: 33328230 PMCID: PMC7744115 DOI: 10.1126/sciadv.abc7209] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 10/27/2020] [Indexed: 06/12/2023]
Abstract
The endoplasmic reticulum (ER) comprises morphologically and functionally distinct domains: sheets and interconnected tubules. These domains undergo dynamic reshaping in response to changes in the cellular environment. However, the mechanisms behind this rapid remodeling are largely unknown. Here, we report that ER remodeling is actively driven by lysosomes, following lysosome repositioning in response to changes in nutritional status: The anchorage of lysosomes to ER growth tips is critical for ER tubule elongation and connection. We validate this causal link via the chemo- and optogenetically driven repositioning of lysosomes, which leads to both a redistribution of the ER tubules and a change of its global morphology. Therefore, lysosomes sense metabolic change in the cell and regulate ER tubule distribution accordingly. Dysfunction in this mechanism during axonal extension may lead to axonal growth defects. Our results demonstrate a critical role of lysosome-regulated ER dynamics and reshaping in nutrient responses and neuronal development.
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Affiliation(s)
- Meng Lu
- Cambridge Infinitus Research Centre, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Francesca W van Tartwijk
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Julie Qiaojin Lin
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0AH, UK
| | - Wilco Nijenhuis
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Pierre Parutto
- Group of Computational Biology and Applied Mathematics, Institut de Biologie de l'École Normale Supérieure-PSL, 46 rue d'Ulm, 75005 Paris, France
| | - Marcus Fantham
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Charles N Christensen
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0AH, UK
| | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Alan Tunnacliffe
- Cambridge Infinitus Research Centre, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - David Holcman
- Group of Computational Biology and Applied Mathematics, Institut de Biologie de l'École Normale Supérieure-PSL, 46 rue d'Ulm, 75005 Paris, France
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, UK
| | - Lukas Kapitein
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Gabriele S Kaminski Schierle
- Cambridge Infinitus Research Centre, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Clemens F Kaminski
- Cambridge Infinitus Research Centre, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK.
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0AH, UK
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161
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Vallese F, Catoni C, Cieri D, Barazzuol L, Ramirez O, Calore V, Bonora M, Giamogante F, Pinton P, Brini M, Calì T. An expanded palette of improved SPLICS reporters detects multiple organelle contacts in vitro and in vivo. Nat Commun 2020; 11:6069. [PMID: 33247103 PMCID: PMC7699637 DOI: 10.1038/s41467-020-19892-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 11/04/2020] [Indexed: 12/21/2022] Open
Abstract
Membrane contact sites between virtually any known organelle have been documented and, in the last decades, their study received momentum due to their importance for fundamental activities of the cell and for the subtle comprehension of many human diseases. The lack of tools to finely image inter-organelle proximity hindered our understanding on how these subcellular communication hubs mediate and regulate cell homeostasis. We develop an improved and expanded palette of split-GFP-based contact site sensors (SPLICS) for the detection of single and multiple organelle contact sites within a scalable distance range. We demonstrate their flexibility under physiological conditions and in living organisms.
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Affiliation(s)
- Francesca Vallese
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | | | - Domenico Cieri
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Lucia Barazzuol
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Omar Ramirez
- Department of Neurobiology, Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Valentina Calore
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Massimo Bonora
- Department of Morphology, Surgery and Experimental Medicine, Section of General Pathology, University of Ferrara, Ferrara, Italy.,Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Flavia Giamogante
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of General Pathology, University of Ferrara, Ferrara, Italy.,Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Marisa Brini
- Department of Biology, University of Padova, Padova, Italy.
| | - Tito Calì
- Department of Biomedical Sciences, University of Padova, Padova, Italy. .,Padova Neuroscience Center (PNC), University of Padova, Padova, Italy.
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162
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Wang J, Fourriere L, Gleeson PA. Local Secretory Trafficking Pathways in Neurons and the Role of Dendritic Golgi Outposts in Different Cell Models. Front Mol Neurosci 2020; 13:597391. [PMID: 33324160 PMCID: PMC7726432 DOI: 10.3389/fnmol.2020.597391] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/19/2020] [Indexed: 12/18/2022] Open
Abstract
A fundamental characteristic of neurons is the relationship between the architecture of the polarized neuron and synaptic transmission between neurons. Intracellular membrane trafficking is paramount to establish and maintain neuronal structure; perturbation in trafficking results in defects in neurodevelopment and neurological disorders. Given the physical distance from the cell body to the distal sites of the axon and dendrites, transport of newly synthesized membrane proteins from the central cell body to their functional destination at remote, distal sites represents a conundrum. With the identification of secretory organelles in dendrites, including endoplasmic reticulum (ER) and Golgi outposts (GOs), recent studies have proposed local protein synthesis and trafficking distinct from the conventional anterograde transport pathways of the cell body. A variety of different model organisms, including Drosophila, zebrafish, and rodents, have been used to probe the organization and function of the local neuronal secretory network. Here, we review the evidence for local secretory trafficking pathways in dendrites in a variety of cell-based neuronal systems and discuss both the similarities and differences in the organization and role of the local secretory organelles, especially the GOs. In addition, we identify the gaps in the current knowledge and the potential advances using human induced pluripotent stem cells (iPSCs) in defining local membrane protein trafficking in human neurons and in understanding the molecular basis of neurological diseases.
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Affiliation(s)
- Jingqi Wang
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Lou Fourriere
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Paul A Gleeson
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
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163
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Gürth CM, Dankovich TM, Rizzoli SO, D'Este E. Synaptic activity and strength are reflected by changes in the post-synaptic secretory pathway. Sci Rep 2020; 10:20576. [PMID: 33239744 PMCID: PMC7688657 DOI: 10.1038/s41598-020-77260-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 11/09/2020] [Indexed: 01/13/2023] Open
Abstract
Neurons are highly asymmetric cells that span long distances and need to react promptly to local demands. Consequently, neuronal secretory pathway elements are distributed throughout neurites, specifically in post-synaptic compartments, to enable local protein synthesis and delivery. Whether and how changes in local synaptic activity correlate to post-synaptic secretory elements is still unclear. To assess this, we used STED nanoscopy and automated quantitative image analysis of post-synaptic markers of the endoplasmic reticulum, ER-Golgi intermediate compartment, trans-Golgi network, and spine apparatus. We found that the distribution of these proteins was dependent on pre-synaptic activity, measured as the amount of recycling vesicles. Moreover, their abundance correlated to both pre- and post-synaptic markers of synaptic strength. Overall, the results suggest that in small, low-activity synapses the secretory pathway components are tightly clustered in the synaptic area, presumably to enable rapid local responses, while bigger synapses utilise secretory machinery components from larger, more diffuse areas.
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Affiliation(s)
- Clara-Marie Gürth
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.,Department of Optical Nanoscopy, Max Planck Institute for Medical Research, Jahnstr. 29, 69120, Heidelberg, Germany
| | - Tal M Dankovich
- Institute for Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Silvio O Rizzoli
- Institute for Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Elisa D'Este
- Optical Microscopy Facility, Max Planck Institute for Medical Research, Jahnstr. 29, 69120, Heidelberg, Germany.
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164
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Datta D, Enwright JF, Arion D, Paspalas CD, Morozov YM, Lewis DA, Arnsten AFT. Mapping Phosphodiesterase 4D (PDE4D) in Macaque Dorsolateral Prefrontal Cortex: Postsynaptic Compartmentalization in Layer III Pyramidal Cell Circuits. Front Neuroanat 2020; 14:578483. [PMID: 33328902 PMCID: PMC7714912 DOI: 10.3389/fnana.2020.578483] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/06/2020] [Indexed: 12/20/2022] Open
Abstract
cAMP signaling has powerful, negative effects on cognitive functions of the primate dorsolateral prefrontal cortex (dlPFC), opening potassium channels to reduce firing and impair working memory, and increasing tau phosphorylation in aging neurons. This contrasts with cAMP actions in classic circuits, where it enhances plasticity and transmitter release. PDE4 isozymes regulate cAMP actions, and thus have been a focus of research and drug discovery. Previous work has focused on the localization of PDE4A and PDE4B in dlPFC, but PDE4D is also of great interest, as it is the predominant PDE4 isoform in primate association cortex, and PDE4D expression decreases with aging in human dlPFC. Here we used laser-capture microdissection transcriptomics and found that PDE4D message is enriched in pyramidal cells compared to GABAergic PV-interneurons in layer III of the human dlPFC. A parallel study in rhesus macaques using high-spatial resolution immunoelectron microscopy revealed the ultrastructural locations of PDE4D in primate dlPFC with clarity not possible in human post-mortem tissue. PDE4D was especially prominent in dendrites associated with microtubules, mitochondria, and likely smooth endoplasmic reticulum (SER). There was substantial postsynaptic labeling in dendritic spines, associated with the SER spine-apparatus near glutamatergic-like axospinous synapses, but sparse labeling in axon terminals. We also observed dense PDE4D labeling perisynaptically in astroglial leaflets ensheathing glutamatergic connections. These data suggest that PDE4D is strategically positioned to regulate cAMP signaling in dlPFC glutamatergic synapses and circuits, especially in postsynaptic compartments where it is localized to influence cAMP actions on intracellular trafficking, mitochondrial physiology, and internal calcium release.
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Affiliation(s)
- Dibyadeep Datta
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - John F. Enwright
- Department of Psychiatry, Translational Neuroscience Program, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Dominique Arion
- Department of Psychiatry, Translational Neuroscience Program, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Constantinos D. Paspalas
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Yury M. Morozov
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - David A. Lewis
- Department of Psychiatry, Translational Neuroscience Program, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Amy F. T. Arnsten
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, United States
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165
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Raeisossadati R, Ferrari MFR. Mitochondria-ER Tethering in Neurodegenerative Diseases. Cell Mol Neurobiol 2020; 42:917-930. [PMID: 33196974 DOI: 10.1007/s10571-020-01008-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 11/11/2020] [Indexed: 12/12/2022]
Abstract
Organelles juxtaposition has been detected for decades, although only recently gained importance due to a pivotal role in the regulation of cellular processes dependent on membrane contact sites. Endoplasmic reticulum (ER) and mitochondria interaction is a prime example of organelles contact sites. Mitochondria-associated membranes (MAM) are proposed to harbor ER-mitochondria tether complexes, mainly when these organelles are less than 30 nm apart. Dysfunctions of proteins located at the MAM are associated with neurodegenerative diseases such as Parkinson's, Alzheimer's and amyotrophic lateral sclerosis, as well as neurodevelopmental disorders; hence any malfunction in MAM can potentially trigger cell death. This review will focus on the role of ER-mitochondria contact sites, regarding calcium homeostasis, lipid metabolism, autophagy, morphology and dynamics of mitochondria, mainly in the context of neurodegenerative diseases. Approaches that have been employed so far to study organelles contact sites, as well as methods that were not used in neurosciences yet, but are promising and accurate ways to unveil the functions of MAM during neurodegeneration, is also discussed in the present review.
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Affiliation(s)
- Reza Raeisossadati
- Departamento de Genetica e Biologia Evolutiva, Instituto de Biociencias, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
| | - Merari F R Ferrari
- Departamento de Genetica e Biologia Evolutiva, Instituto de Biociencias, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
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166
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Weiner A. Step-by-step guide to post-acquisition correlation of confocal and FIB/SEM volumes using Amira software. Methods Cell Biol 2020; 162:333-351. [PMID: 33707018 DOI: 10.1016/bs.mcb.2020.09.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In recent years new methodologies and workflow pipelines for acquiring correlated fluorescence microscopy and volume electron microscopy datasets have been extensively described and made accessible to users of different levels. Post-acquisition image processing, and particularly correlation of the optical and electron data in a single integrated three-dimensional framework can be key for extracting valuable information, especially when imaging large sample volumes such as whole cells or tissues. These tasks remain challenging and are often rate-limiting to most users. Here we provide a step-by-step guide to image processing and manual correlation using ImageJ and Amira software of a confocal microscopy stack and a focused ion beam/scanning electron microscopy (FIB/SEM) tomogram acquired using a correlative pipeline. These previously published datasets capture a highly transient invasion event by the bacterium Shigella flexneri infecting an epithelial cell grown in culture, and are made available here in their pre-processed form for readers who wish to gain hands-on experience in image processing and correlation using existing data. In this guide we describe a simple protocol for correlation based on internal sample features clearly visible by both fluorescence and electron microscopy, which is normally sufficient when correlating standard fluorescence microscopy stacks with FIB/SEM data. While the guide describes the treatment of specific datasets, it is applicable to a wide variety of samples and different microscopy approaches that require basic correlation and visualization of two or more datasets in a single integrated framework.
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Affiliation(s)
- Allon Weiner
- Centre d'Immunologie et des Maladies Infectieuses, Cimi-Paris, Inserm, Sorbonne Université, Paris, France.
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167
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Protrudin functions from the endoplasmic reticulum to support axon regeneration in the adult CNS. Nat Commun 2020; 11:5614. [PMID: 33154382 PMCID: PMC7645621 DOI: 10.1038/s41467-020-19436-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 10/14/2020] [Indexed: 12/12/2022] Open
Abstract
Adult mammalian central nervous system axons have intrinsically poor regenerative capacity, so axonal injury has permanent consequences. One approach to enhancing regeneration is to increase the axonal supply of growth molecules and organelles. We achieved this by expressing the adaptor molecule Protrudin which is normally found at low levels in non-regenerative neurons. Elevated Protrudin expression enabled robust central nervous system regeneration both in vitro in primary cortical neurons and in vivo in the injured adult optic nerve. Protrudin overexpression facilitated the accumulation of endoplasmic reticulum, integrins and Rab11 endosomes in the distal axon, whilst removing Protrudin’s endoplasmic reticulum localization, kinesin-binding or phosphoinositide-binding properties abrogated the regenerative effects. These results demonstrate that Protrudin promotes regeneration by functioning as a scaffold to link axonal organelles, motors and membranes, establishing important roles for these cellular components in mediating regeneration in the adult central nervous system. Increasing the supply of growth machinery to axons is a potential strategy for promoting repair after injury. Here the authors demonstrate that the endoplasmic reticulum adaptor molecule Protrudin provides cellular components that support axonal regeneration in the adult CNS.
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168
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ER-Mitochondria Contact Sites Reporters: Strengths and Weaknesses of the Available Approaches. Int J Mol Sci 2020; 21:ijms21218157. [PMID: 33142798 PMCID: PMC7663704 DOI: 10.3390/ijms21218157] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 12/12/2022] Open
Abstract
Organelle intercommunication represents a wide area of interest. Over the last few decades, increasing evidence has highlighted the importance of organelle contact sites in many biological processes including Ca2+ signaling, lipid biosynthesis, apoptosis, and autophagy but also their involvement in pathological conditions. ER–mitochondria tethering is one of the most investigated inter-organelle communications and it is differently modulated in response to several cellular conditions including, but not limited to, starvation, Endoplasmic Reticulum (ER) stress, and mitochondrial shape modifications. Despite many studies aiming to understand their functions and how they are perturbed under different conditions, approaches to assess organelle proximity are still limited. Indeed, better visualization and characterization of contact sites remain a fascinating challenge. The aim of this review is to summarize strengths and weaknesses of the available methods to detect and quantify contact sites, with a main focus on ER–mitochondria tethering.
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169
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Bergami M, Motori E. Reweaving the Fabric of Mitochondrial Contact Sites in Astrocytes. Front Cell Dev Biol 2020; 8:592651. [PMID: 33195262 PMCID: PMC7649784 DOI: 10.3389/fcell.2020.592651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/06/2020] [Indexed: 12/17/2022] Open
Abstract
The endoplasmic reticulum (ER) and mitochondria are classically regarded as very dynamic organelles in cell lines. Their frequent morphological changes and repositioning underlie the transient generation of physical contact sites (so-called mitochondria-ER contacts, or MERCs) which are believed to support metabolic processes central for cellular signaling and function. The extent of regulation over these organelle dynamics has likely further achieved a higher level of complexity in polarized cells like neurons and astrocytes to match their elaborated geometries and specialized functions, thus ensuring the maintenance of MERCs at metabolically demanding locations far from the soma. Yet, live imaging of adult brain tissue has recently revealed that the true extent of mitochondrial dynamics in astrocytes is significantly lower than in cell culture settings. On one hand, this suggests that organelle dynamics in mature astroglia in vivo may be highly regulated and perhaps triggered only by defined physiological stimuli. On the other hand, this extent of control may greatly facilitate the stabilization of those MERCs required to maintain regionalized metabolic domains underlying key astrocytic functions. In this perspective, we review recent evidence suggesting that the resulting spatial distribution of mitochondria and ER in astrocytes in vivo may create the conditions for maintaining extensive MERCs within specialized territories – like perivascular endfeet – and discuss the possibility that their enrichment at these distal locations may facilitate specific forms of cellular plasticity relevant for physiology and disease.
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Affiliation(s)
- Matteo Bergami
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University Hospital Cologne, Cologne, Germany.,Institute of Genetics, University of Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Elisa Motori
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University Hospital Cologne, Cologne, Germany.,Max Planck Institute for Biology of Ageing, Cologne, Germany
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170
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Dolphin AC. Functions of Presynaptic Voltage-gated Calcium Channels. FUNCTION (OXFORD, ENGLAND) 2020; 2:zqaa027. [PMID: 33313507 PMCID: PMC7709543 DOI: 10.1093/function/zqaa027] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/16/2020] [Accepted: 10/20/2020] [Indexed: 01/06/2023]
Abstract
Voltage-gated calcium channels are the principal conduits for depolarization-mediated Ca2+ entry into excitable cells. In this review, the biophysical properties of the relevant members of this family of channels, those that are present in presynaptic terminals, will be discussed in relation to their function in mediating neurotransmitter release. Voltage-gated calcium channels have properties that ensure they are specialized for particular roles, for example, differences in their activation voltage threshold, their various kinetic properties, and their voltage-dependence of inactivation. All these attributes play into the ability of the various voltage-gated calcium channels to participate in different patterns of presynaptic vesicular release. These include synaptic transmission resulting from single action potentials, and longer-term changes mediated by bursts or trains of action potentials, as well as release resulting from graded changes in membrane potential in specialized sensory synapses.
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK,Address correspondence to A.C.D. (e-mail: )
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171
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Hawkins NA, Misra SN, Jurado M, Kang SK, Vierra NC, Nguyen K, Wren L, George AL, Trimmer JS, Kearney JA. Epilepsy and neurobehavioral abnormalities in mice with a dominant-negative KCNB1 pathogenic variant. Neurobiol Dis 2020; 147:105141. [PMID: 33132203 PMCID: PMC7725922 DOI: 10.1016/j.nbd.2020.105141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 10/04/2020] [Accepted: 10/12/2020] [Indexed: 11/23/2022] Open
Abstract
Developmental and epileptic encephalopathies (DEE) are a group of severe epilepsies that usually present with intractable seizures, developmental delay, and often have elevated risk for premature mortality. Numerous genes have been identified as a monogenic cause of DEE, including KCNB1. The voltage-gated potassium channel Kv2.1, encoded by KCNB1, is primarily responsible for delayed rectifier potassium currents that are important regulators of excitability in electrically excitable cells, including neurons. In addition to its canonical role as a voltage-gated potassium conductance, Kv2.1 also serves a highly conserved structural function organizing endoplasmic reticulum-plasma membrane junctions clustered in the soma and proximal dendrites of neurons. The de novo pathogenic variant KCNB1-p.G379R was identified in an infant with epileptic spasms, and atonic, focal and tonic-clonic seizures that were refractory to treatment with standard antiepileptic drugs. Previous work demonstrated deficits in potassium conductance, but did not assess non-conducting functions. To determine if the G379R variant affected Kv2.1 clustering at endoplasmic reticulum-plasma membrane junctions, Kv2.1-G379R was expressed in HEK293T cells. Kv2.1-G379R expression did not induce formation of endoplasmic reticulum-plasma membrane junctions, and co-expression of Kv2.1-G379R with Kv2.1-wild-type lowered induction of these structures relative to Kv2.1-WT alone, consistent with a dominant negative effect. To model this variant in vivo, we introduced Kcnb1G379R into mice using CRISPR/Cas9 genome editing. We characterized neuronal expression, neurological and neurobehavioral phenotypes of Kcnb1G379R/+ (Kcnb1R/+) and Kcnb1G379R/G379R (Kcnb1R/R) mice. Immunohistochemistry studies on brains from Kcnb1+/+, Kcnb1R/+ and Kcnb1R/R mice revealed genotype-dependent differences in the expression levels of Kv2.1 protein, as well as associated Kv2.2 and AMIGO-1 proteins. Kcnb1R/+ and Kcnb1R/R mice displayed profound hyperactivity, repetitive behaviors, impulsivity and reduced anxiety. Spontaneous seizures were observed in Kcnb1R/R mice, as well as seizures induced by exposure to novel environments and/ or handling. Both Kcnb1R/+ and Kcnb1R/R mutants were more susceptible to proconvulsant-induced seizures. In addition, both Kcnb1R/+ and Kcnb1R/R mice exhibited abnormal interictal EEG activity, including isolated spike and slow waves. Overall, the Kcnb1G379R mice recapitulate many features observed in individuals with DEE due to pathogenic variants in KCNB1. This new mouse model of KCNB1-associated DEE will be valuable for improving the understanding of the underlying pathophysiology and will provide a valuable tool for the development of therapies to treat this pharmacoresistant DEE.
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Affiliation(s)
- Nicole A Hawkins
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Sunita N Misra
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America; Ann & Robert H. Lurie Children's Hospital of Chicago Chicago, IL 60611, United States of America
| | - Manuel Jurado
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Seok Kyu Kang
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Nicholas C Vierra
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, United States of America; Department of preceding Physiology and Membrane Biology, University of California, Davis, CA 95616, United States of America
| | - Kimberly Nguyen
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, United States of America
| | - Lisa Wren
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - James S Trimmer
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, United States of America; Department of preceding Physiology and Membrane Biology, University of California, Davis, CA 95616, United States of America
| | - Jennifer A Kearney
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America.
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172
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Yan R, Chen K, Xu K. Probing Nanoscale Diffusional Heterogeneities in Cellular Membranes through Multidimensional Single-Molecule and Super-Resolution Microscopy. J Am Chem Soc 2020; 142:18866-18873. [PMID: 33084318 DOI: 10.1021/jacs.0c08426] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Diffusion properties notably determine the behavior of biomembranes. Here we report the concurrent nanoscale fine-mapping of membrane topography, diffusivity, and packing order in live mammalian cells through a synergy of single-molecule and super-resolution methods. By identifying a bright, lipophilic fluorescence turn-on probe that enables sustained single-molecule imaging of cellular membranes under stroboscopic excitation, we accumulate the positions and transient displacements of >106 probe molecules to achieve super-resolution topography and diffusivity mapping. We thus determine a trend that the membrane diffusivity drops with increased lipid packing order when comparing the endoplasmic reticulum (ER) membrane, plasma membrane, and nanodomains induced by cholera toxin B. Utilizing our nanoscale mapping capability, we further unveil reduced diffusivity in the ER membrane at ER-plasma membrane contact sites. By next integrating spectrally resolved single-molecule imaging, we show that this localized diffusion slowdown is not due to altered lipid packing order but may instead be attributed to local protein crowding. Our integrated multidimensional single-molecule approach thus unveils and differentiates between nanoscale diffusional heterogeneities of different origins in live-cell membranes.
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Affiliation(s)
- Rui Yan
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chan Zuckerberg Biohub, San Francisco, California 94158, United States
| | - Kun Chen
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chan Zuckerberg Biohub, San Francisco, California 94158, United States
| | - Ke Xu
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chan Zuckerberg Biohub, San Francisco, California 94158, United States
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173
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Calizo RC, Bell MK, Ron A, Hu M, Bhattacharya S, Wong NJ, Janssen WGM, Perumal G, Pederson P, Scarlata S, Hone J, Azeloglu EU, Rangamani P, Iyengar R. Cell shape regulates subcellular organelle location to control early Ca 2+ signal dynamics in vascular smooth muscle cells. Sci Rep 2020; 10:17866. [PMID: 33082406 PMCID: PMC7576209 DOI: 10.1038/s41598-020-74700-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/05/2020] [Indexed: 12/23/2022] Open
Abstract
The shape of the cell is connected to its function; however, we do not fully understand underlying mechanisms by which global shape regulates a cell's functional capabilities. Using theory, experiments and simulation, we investigated how physiologically relevant cell shape changes affect subcellular organization, and consequently intracellular signaling, to control information flow needed for phenotypic function. Vascular smooth muscle cells going from a proliferative and motile circular shape to a contractile fusiform shape show changes in the location of the sarcoplasmic reticulum, inter-organelle distances, and differential distribution of receptors in the plasma membrane. These factors together lead to the modulation of signals transduced by the M3 muscarinic receptor/Gq/PLCβ pathway at the plasma membrane, amplifying Ca2+ dynamics in the cytoplasm, and the nucleus resulting in phenotypic changes, as determined by increased activity of myosin light chain kinase in the cytoplasm and enhanced nuclear localization of the transcription factor NFAT. Taken together, our observations show a systems level phenomenon whereby global cell shape affects subcellular organization to modulate signaling that enables phenotypic changes.
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Affiliation(s)
- R C Calizo
- Department of Pharmacological Sciences, Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1215, New York, NY, 10029, USA
| | - M K Bell
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - A Ron
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - M Hu
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - S Bhattacharya
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - N J Wong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - W G M Janssen
- Department of Pharmacological Sciences, Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1215, New York, NY, 10029, USA
| | - G Perumal
- Carl Zeiss Microscopy LLC, White Plains, NY, 10601, USA
| | - P Pederson
- Carl Zeiss Microscopy LLC, White Plains, NY, 10601, USA
| | - S Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, 01609, USA
| | - J Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - E U Azeloglu
- Department of Pharmacological Sciences, Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1215, New York, NY, 10029, USA
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - P Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, 92093, USA.
| | - R Iyengar
- Department of Pharmacological Sciences, Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1215, New York, NY, 10029, USA.
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174
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Cortical Presynaptic Boutons Progressively Engulf Spinules as They Mature. eNeuro 2020; 7:ENEURO.0426-19.2020. [PMID: 32958478 PMCID: PMC7568603 DOI: 10.1523/eneuro.0426-19.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 08/20/2020] [Accepted: 09/08/2020] [Indexed: 01/01/2023] Open
Abstract
Despite decades of discussion in the neuroanatomical literature, the role of the synaptic "spinule" in synaptic development and function remains elusive. Canonically, spinules are finger-like projections that emerge from postsynaptic spines and can become enveloped by presynaptic boutons. When a presynaptic bouton encapsulates a spinule in this manner, the membrane apposition between the spinule and surrounding bouton can be significantly larger than the membrane interface at the synaptic active zone. Hence, spinules may represent a mechanism for extrasynaptic neuronal communication and/or may function as structural "anchors" that increase the stability of cortical synapses. Yet despite their potential to impact synaptic function, we have little information on the percentages of developing and adult cortical bouton populations that contain spinules, the percentages of these cortical spinule-bearing boutons (SBBs) that contain spinules from distinct neuronal/glial origins, or whether the onset of activity or cortical plasticity are correlated with increased prevalence of cortical SBBs. Here, we employed 2D and 3D electron microscopy to determine the prevalence of spinules in excitatory presynaptic boutons at key developmental time points in the primary visual cortex (V1) of female and male ferrets. We find that the prevalence of SBBs in V1 increases across postnatal development, such that ∼25% of excitatory boutons in late adolescent ferret V1 contain spinules. In addition, we find that a majority of spinules within SBBs at later developmental time points emerge from postsynaptic spines and adjacent boutons/axons, suggesting that synaptic spinules may enhance synaptic stability and allow for axo-axonal communication in mature sensory cortex.
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175
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Endoplasmic reticulum visits highly active spines and prevents runaway potentiation of synapses. Nat Commun 2020; 11:5083. [PMID: 33033259 PMCID: PMC7546627 DOI: 10.1038/s41467-020-18889-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 09/17/2020] [Indexed: 11/25/2022] Open
Abstract
In hippocampal pyramidal cells, a small subset of dendritic spines contain endoplasmic reticulum (ER). In large spines, ER frequently forms a spine apparatus, while smaller spines contain just a single tubule of smooth ER. Here we show that the ER visits dendritic spines in a non-random manner, targeting spines during periods of high synaptic activity. When we blocked ER motility using a dominant negative approach against myosin V, spine synapses became stronger compared to controls. We were not able to further potentiate these maxed-out synapses, but long-term depression (LTD) was readily induced by low-frequency stimulation. We conclude that the brief ER visits to active spines have the important function of preventing runaway potentiation of individual spine synapses, keeping most of them at an intermediate strength level from which both long-term potentiation (LTP) and LTD are possible. In hippocampal pyramidal cells, a subset of dendritic spines contain endoplasmic reticulum (ER). Here, the authors show that ER enters dendritic spines in a non-random manner, during high synaptic activity with the function of limiting synaptic strength.
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176
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Filadi R, Pizzo P. Mitochondrial calcium handling and neurodegeneration: when a good signal goes wrong. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.08.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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177
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S Narasimhan KK, Devarajan A, Karan G, Sundaram S, Wang Q, van Groen T, Monte FD, Rajasekaran NS. Reductive stress promotes protein aggregation and impairs neurogenesis. Redox Biol 2020; 37:101739. [PMID: 33242767 PMCID: PMC7695986 DOI: 10.1016/j.redox.2020.101739] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 09/23/2020] [Indexed: 12/20/2022] Open
Abstract
Redox homeostasis regulates key cellular signaling in both physiology and pathology. While perturbations result in shifting the redox homeostasis towards oxidative stress are well documented, the influence of reductive stress (RS) in neurodegenerative diseases and its mechanisms are unknown. Here, we postulate that a redox shift towards the reductive arm (through the activation of Nrf2 signaling) will damage neurons and impair neurogenesis. In proliferating and differentiating neuroblastoma (Neuro 2a/N2a) cells, sulforaphane-mediated Nrf2 activation resulted in increased transcription/translation of antioxidants and glutathione (GSH) production along with significantly declined ROS in a dose-dependent manner leading to a reductive-redox state (i.e. RS). Interestingly, this resulted in endoplasmic reticulum (ER) stress leading to subsequent protein aggregation/proteotoxicity in neuroblastoma cells. Under RS, we also observed elevated Tau/α-synuclein and their co-localization with other protein aggregates in these cells. Surprisingly, we noticed that acute RS impaired neurogenesis as evidenced from reduced neurite outgrowth/length. Furthermore, maintaining the cells in a sustained RS condition (for five consecutive generations) dramatically reduced their differentiation and prevented the formation of axons (p < 0.05). This impairment in RS mediated neurogenesis occurs through the alteration of Tau dynamics i.e. RS activates the pathogenic GSK3β/Tau cascade thereby promoting the phosphorylation of Tau leading to proteotoxicity. Of note, intermittent withdrawal of sulforaphane from these cells suppressed the proteotoxic insult and re-activated the differentiation process. Overall, this results suggest that either acute or chronic RS could hamper neurogenesis through GSK3β/TAU signaling and proteotoxicity. Therefore, investigations identifying novel redox mechanisms impacting proteostasis are crucial to preserve neuronal health.
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Affiliation(s)
- Kishore Kumar S Narasimhan
- Cardiac Aging & Redox Signaling Laboratory, Molecular and Cellular Pathology, Department of Pathology, Birmingham, AL, USA
| | - Asokan Devarajan
- Department of Medicine, Division of Cardiology, Cardiac Arrhythmia Center and Neurocardiology Research Center of Excellence, University of California, Los Angeles, CA, United States
| | - Goutam Karan
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Sandhya Sundaram
- Department of Pathology, Sri Ramachandra Medical University & Research Institute, Chennai, India
| | - Qin Wang
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Thomas van Groen
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Federica Del Monte
- Gazes Cardiac Research Institute, Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - Namakkal S Rajasekaran
- Cardiac Aging & Redox Signaling Laboratory, Molecular and Cellular Pathology, Department of Pathology, Birmingham, AL, USA; Division of Cardiovascular Medicine, Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA; Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, USA.
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178
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Yao PJ, Eren E, Petralia RS, Gu JW, Wang YX, Kapogiannis D. Mitochondrial Protrusions in Neuronal Cells. iScience 2020; 23:101514. [PMID: 32942173 PMCID: PMC7501463 DOI: 10.1016/j.isci.2020.101514] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 07/15/2020] [Accepted: 08/25/2020] [Indexed: 12/30/2022] Open
Abstract
Mitochondrial function relies on multiple quality control mechanisms, including the release of mitochondrial vesicles. To investigate the ultrastructure and prevalence of mitochondrial membranous protrusions (and, by extension, vesicles) in neurons, we surveyed mitochondria in rat and planarian brains using transmission electron microscopy (EM). We observed that mitochondrial protrusions mostly extend from the outer membrane. Leveraging available 3D EM datasets of the brain, we further analyzed mitochondrial protrusions in neurons of mouse and Drosophila brains, identifying high-resolution spatial views of these protrusions. To assess whether the abundance of mitochondrial protrusions and mitochondria-derived vesicles respond to cellular stress, we examined neurons expressing fluorescently tagged mitochondrial markers using confocal microscopy with Airyscan and found increased numbers of mitochondrial protrusions and vesicles with mild stress. Future studies using improved spatial resolution with added temporal information may further define the functional implications of mitochondrial protrusions and vesicles in neurons.
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Affiliation(s)
- Pamela J. Yao
- Laboratory of Clinical Investigation, NIA/NIH Biomedical Research Center, Baltimore, MD 21224, USA
| | - Erden Eren
- Laboratory of Clinical Investigation, NIA/NIH Biomedical Research Center, Baltimore, MD 21224, USA
| | | | - Jeffrey W. Gu
- Laboratory of Clinical Investigation, NIA/NIH Biomedical Research Center, Baltimore, MD 21224, USA
| | - Ya-Xian Wang
- Advanced Imaging Core, NIDCD/NIH, Bethesda, MD 20892, USA
| | - Dimitrios Kapogiannis
- Laboratory of Clinical Investigation, NIA/NIH Biomedical Research Center, Baltimore, MD 21224, USA
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179
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Stacchiotti A, Corsetti G. Natural Compounds and Autophagy: Allies Against Neurodegeneration. Front Cell Dev Biol 2020; 8:555409. [PMID: 33072744 PMCID: PMC7536349 DOI: 10.3389/fcell.2020.555409] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 09/01/2020] [Indexed: 12/12/2022] Open
Abstract
Prolonging the healthy life span and limiting neurological illness are imperative goals in gerontology. Age-related neurodegeneration is progressive and leads to severe diseases affecting motility, memory, cognitive function, and social life. To date, no effective treatments are available for neurodegeneration and irreversible neuronal loss. Bioactive phytochemicals could represent a natural alternative to ensure active aging and slow onset of neurodegenerative diseases in elderly patients. Autophagy or macroautophagy is an evolutionarily conserved clearing process that is needed to remove aggregate-prone proteins and organelles in neurons and glia. It also is crucial in synaptic plasticity. Aberrant autophagy has a key role in aging and neurodegeneration. Recent evidence indicates that polyphenols like resveratrol and curcumin, flavonoids, like quercetin, polyamine, like spermidine and sugars, like trehalose, limit brain damage in vitro and in vivo. Their common mechanism of action leads to restoration of efficient autophagy by dismantling misfolded proteins and dysfunctional mitochondria. This review focuses on the role of dietary phytochemicals as modulators of autophagy to fight Alzheimer's and Parkinson's diseases, fronto-temporal dementia, amyotrophic lateral sclerosis, and psychiatric disorders. Currently, most studies have involved in vitro or preclinical animal models, and the therapeutic use of phytochemicals in patients remains limited.
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Affiliation(s)
- Alessandra Stacchiotti
- Division of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy.,Interdepartmental University Center of Research "Adaptation and Regeneration of Tissues and Organs (ARTO)," University of Brescia, Brescia, Italy
| | - Giovanni Corsetti
- Division of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
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180
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Cui Y, Wen X, Nan Y, Xiang G, Wei Z, Wei L, Xia Y, Li Q. Overexpressed PERK suppresses the neurodegenerative phenotypes in PINK1 B9 flies by enhancing mitochondrial function. Neurochem Int 2020; 140:104825. [PMID: 32898622 DOI: 10.1016/j.neuint.2020.104825] [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: 03/06/2020] [Revised: 07/14/2020] [Accepted: 08/03/2020] [Indexed: 11/30/2022]
Abstract
PTEN-induced putative kinase 1 (PINK1) mutation induces autosomal recessive Parkinson's Disease (PD), mitochondrial dysfunction is the central pathogenic process. However, more and more studies presented the bulk of the damage to neurons with mitochondrial dysfunction stems from the endoplasmic reticulum (ER) stress. In mitochondria damaged PINK1B9 fly model how protein kinase RNA-like ER kinase (PERK) arm of ER stress functions remains a mystery. Thus, we generated both PERK overexpressed (PEK OE) and down expressed (PEK RNAi) PINK1B9 flies and monitored their motor activity. We found PEK OE decreased the abnormal wing posture rate and rescued PINK1B9 flies' motor activity. Furthermore, we observed the increased number of dopaminergic neurons of protocerebral posterior lateral 1 (PPL1) and the tyrosine hydroxylase (TH) protein levels in PINK1B9 flies. When testing the mitochondrial morphology in flight muscle with TEM, we found that the shape of the mitochondria became normal. The ATP levels of flight muscle tissues were significantly elevated in PEK OE PINK1B9 flies with the increased function of mitochondrial Electron Transport Chain (ETC) Complex I (CI) but not Complex Ⅱ (CⅡ) which is further confirmed by oxygen consumption experiments, Western Blot, and RT-PCR to examine the corresponding subunits. We suggest that overexpression of PERK can rescue PINK1B9 PD flies' pathogenic phenotypes and it is linked with the improved mitochondrial function especially CI of ETC but not CⅡ. Our findings may pave a way for the target of the drug for alleviating the suffering of PINK1 mutant autosomal recessive PD patients.
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Affiliation(s)
- Ying Cui
- Department of Neurology, Xiangya Hospital of Central South University, Changsha, Hunan, 410008, China; Guilin Medical University, Guilin, Guangxi, 541004, China; Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Xueyi Wen
- Guilin Medical University, Guilin, Guangxi, 541004, China
| | - Yuyu Nan
- Department of Neurology, Xiangya Hospital of Central South University, Changsha, Hunan, 410008, China; Guilin Medical University, Guilin, Guangxi, 541004, China
| | - Guoliang Xiang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, 450052, China
| | - Zaiwa Wei
- Guilin Medical University, Guilin, Guangxi, 541004, China
| | - Lili Wei
- Guilin Medical University, Guilin, Guangxi, 541004, China
| | - Yang Xia
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Qinghua Li
- Department of Neurology, Xiangya Hospital of Central South University, Changsha, Hunan, 410008, China; Guilin Medical University, Guilin, Guangxi, 541004, China.
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181
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Singh M, Vaishnav PK, Dinda AK, Mohanty S. Evaluation of Priming Efficiency of Forskolin in Tissue-Specific Human Mesenchymal Stem Cells into Dopaminergic Neurons: An In Vitro Comparative Study. Cells 2020; 9:cells9092058. [PMID: 32917012 PMCID: PMC7565008 DOI: 10.3390/cells9092058] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/03/2020] [Accepted: 09/07/2020] [Indexed: 12/18/2022] Open
Abstract
Background: Human mesenchymal stem cells (hMSC) can be derived from various tissue sources and differentiated into dopaminergic (DAergic) neurons using various types of inducers. There are several strategies that have been reported to generate functional dopaminergic neuronal cells from hMSCs in the most efficient manner possible. However, this area is still under extensive research. In this study, we aim to compare hMSCs derived from bone marrow (BM), adipose tissue (AD) and dental pulp (DP) to generate functional dopaminergic neurons, using FGF2 and forskolin. Post-differentiation, multiple factors were used to characterize the cells at morphological, morphometric, ultra-structural, mRNA and protein levels for various markers (Nestin, NF, MAP2, Tuj1, TH, DAT, PitX3, Ngn2, Kv4.2, SCN5A). Cells’ functionality was studied by calcium ion imaging, along with the amount of dopamine secreted by the cells in the culture medium. Results: Data analysis revealed that forskolin has comparable effect on BM- and AD-derived MSC (28.43% and 29.46% DAergic neurons, respectively), whereas DP-MSC (42.78 ± 1.248% DAergic neurons) show better outcome in terms of efficient generation of DAergic neuronal cells, expression of neuronal associated markers, dopamine release and calcium ion efflux. Ultra-structural studies by SEM and TEM also revealed a substantial change in both cellular morphology and composition of cellular organelles. It was observed that AD-MSCs showed the best neuronal features, at morphological, gene, and protein levels upon induction with the above-mentioned induction cocktail. Conclusion: It may be concluded that a combination of FGF2 and forskolin yields functionally active dopaminergic neuronal cells in vitro, with highest percentage of the same from AD-MSCs, as compared to that in BM-MSCs and DP-MSCs. The outcomes and comparative evaluation provide a substantial platform for further studies on molecular pathways involved in the process of DAergic neurogenesis in individual cases.
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Affiliation(s)
- Manisha Singh
- Stem Cell Facility (DBT-Centre of Excellence for Stem Cell Research), All India Institute of Medical Sciences, New Delhi 110029, India;
- Dr. Solomon H. Snyder Department of Neurosciences, Johns Hopkins University, Baltimore, MA 21218, USA
| | | | - Amit Kumar Dinda
- Department of Pathology, All India Institute of Medical Sciences, New Delhi 110029, India;
| | - Sujata Mohanty
- Stem Cell Facility (DBT-Centre of Excellence for Stem Cell Research), All India Institute of Medical Sciences, New Delhi 110029, India;
- Correspondence: ; Tel.: +91-986-839-8194 or +91-981-029-1336
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182
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Guo J, Wang G, Tang W, Song D, Wang X, Hong J, Zhang Z. An optimized approach using cryofixation for high-resolution 3D analysis by FIB-SEM. J Struct Biol 2020; 212:107600. [PMID: 32798655 DOI: 10.1016/j.jsb.2020.107600] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 08/07/2020] [Accepted: 08/09/2020] [Indexed: 01/10/2023]
Abstract
Compared with conventional two-dimensional transmission electron microscopy (TEM), focused ion beam scanning electron microscopy (FIB-SEM) can provide more comprehensive 3D information on cell substructures at the nanometer scale. Biological samples prepared by cryofixation using high-pressure freezing demonstrate optimal preservation of the morphology of cellular structures, as these are arrested instantly in their near-native states. However, samples from cryofixation often show a weak back-scatter electron signal and bad image contrast in FIB-SEM imaging. In addition, it is impossible to do large amounts of heavy metal staining. This is commonly achieved via established osmium impregnation (OTO) en bloc staining protocols. Here, we compared the FIB-SEM image quality of brain tissues prepared using several common freeze-substitution media, and we developed an approach that overcomes these limitations through a combination of osmium tetroxide, uranyl acetate, tannic acid, and potassium permanganate at proper concentrations, respectively. Using this optimized sample preparation protocol for high-pressure freezing and freeze-substitution, perfect smooth membrane morphology, even of the lipid bilayers of the cell membrane, was readily obtained using FIB-SEM. In addition, our protocol is broadly applicable and we demonstrated successful application to brain tissues, plant tissues, Caenorhabditis elegans, Candida albicans, and chlorella. This approach combines the potential of cryofixation for 3D large volume analysis of subcellular structures with the high-resolution capabilities of FIB-SEM.
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Affiliation(s)
- Jiansheng Guo
- Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 310058 Hangzhou, Zhejiang, China; Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, 310058 Hangzhou, Zhejiang, China
| | - Guan Wang
- Department of Neurobiology, Zhejiang University School of Medicine, 310058 Hangzhou, Zhejiang, China
| | - Wen Tang
- Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 310058 Hangzhou, Zhejiang, China
| | - Dandan Song
- Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, 310058 Hangzhou, Zhejiang, China
| | - Xinqiu Wang
- Institute of Insect Science, Zhejiang University, Hangzhou 310058, China
| | - Jian Hong
- Center of Analysis and Measurement, Zhejiang University, Hangzhou 310029, China
| | - Zhongkai Zhang
- Biotechnology and Genetic Germplasm Resources Research Institute, Yunnan Academy of Agricultural Sciences, Key Lab of Southwestern Crop Gene Resources and Germplasm Innovation Ministry of Agriculture and Rural Affairs, Key Lab of Agricultural Biotechnology of Yunnan Province, Kunming 650205, Yunnan, China.
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183
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Gella A, Prada-Dacasa P, Carrascal M, Urpi A, González-Torres M, Abian J, Sanz E, Quintana A. Mitochondrial Proteome of Affected Glutamatergic Neurons in a Mouse Model of Leigh Syndrome. Front Cell Dev Biol 2020; 8:660. [PMID: 32850799 PMCID: PMC7399339 DOI: 10.3389/fcell.2020.00660] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 07/01/2020] [Indexed: 01/03/2023] Open
Abstract
Defects in mitochondrial function lead to severe neuromuscular orphan pathologies known as mitochondrial disease. Among them, Leigh Syndrome is the most common pediatric presentation, characterized by symmetrical brain lesions, hypotonia, motor and respiratory deficits, and premature death. Mitochondrial diseases are characterized by a marked anatomical and cellular specificity. However, the molecular determinants for this susceptibility are currently unknown, hindering the efforts to find an effective treatment. Due to the complex crosstalk between mitochondria and their supporting cell, strategies to assess the underlying alterations in affected cell types in the context of mitochondrial dysfunction are critical. Here, we developed a novel virus-based tool, the AAV-mitoTag viral vector, to isolate mitochondria from genetically defined cell types. Expression of the AAV-mitoTag in the glutamatergic vestibular neurons of a mouse model of Leigh Syndrome lacking the complex I subunit Ndufs4 allowed us to assess the proteome and acetylome of a subset of susceptible neurons in a well characterized model recapitulating the human disease. Our results show a marked reduction of complex I N-module subunit abundance and an increase in the levels of the assembly factor NDUFA2. Transiently associated non-mitochondrial proteins such as PKCδ, and the complement subcomponent C1Q were also increased in Ndufs4-deficient mitochondria. Furthermore, lack of Ndufs4 induced ATP synthase complex and pyruvate dehydrogenase (PDH) subunit hyperacetylation, leading to decreased PDH activity. We provide novel insight on the pathways involved in mitochondrial disease, which could underlie potential therapeutic approaches for these pathologies.
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Affiliation(s)
- Alejandro Gella
- Mitochondrial Neuropathology Lab, Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Patricia Prada-Dacasa
- Mitochondrial Neuropathology Lab, Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Department of Cellular Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Montserrat Carrascal
- Proteomics Laboratory CSIC/UAB, Institute of Biomedical Research of Barcelona, Spanish National Research Council (IIBB-CSIC/IDIBAPS), Barcelona, Spain
| | - Andrea Urpi
- Mitochondrial Neuropathology Lab, Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Melania González-Torres
- Mitochondrial Neuropathology Lab, Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Joaquin Abian
- Proteomics Laboratory CSIC/UAB, Institute of Biomedical Research of Barcelona, Spanish National Research Council (IIBB-CSIC/IDIBAPS), Barcelona, Spain
| | - Elisenda Sanz
- Mitochondrial Neuropathology Lab, Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Department of Cellular Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Albert Quintana
- Mitochondrial Neuropathology Lab, Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Department of Cellular Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Spain
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184
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Kichuk TC, Carrasco-López C, Avalos JL. Lights up on organelles: Optogenetic tools to control subcellular structure and organization. WIREs Mech Dis 2020; 13:e1500. [PMID: 32715616 DOI: 10.1002/wsbm.1500] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/26/2020] [Accepted: 05/31/2020] [Indexed: 12/21/2022]
Abstract
Since the neurobiological inception of optogenetics, light-controlled molecular perturbations have been applied in many scientific disciplines to both manipulate and observe cellular function. Proteins exhibiting light-sensitive conformational changes provide researchers with avenues for spatiotemporal control over the cellular environment and serve as valuable alternatives to chemically inducible systems. Optogenetic approaches have been developed to target proteins to specific subcellular compartments, allowing for the manipulation of nuclear translocation and plasma membrane morphology. Additionally, these tools have been harnessed for molecular interrogation of organelle function, location, and dynamics. Optogenetic approaches offer novel ways to answer fundamental biological questions and to improve the efficiency of bioengineered cell factories by controlling the assembly of synthetic organelles. This review first provides a summary of available optogenetic systems with an emphasis on their organelle-specific utility. It then explores the strategies employed for organelle targeting and concludes by discussing our perspective on the future of optogenetics to control subcellular structure and organization. This article is categorized under: Metabolic Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Therese C Kichuk
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - César Carrasco-López
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, USA
| | - José L Avalos
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, USA.,Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey, USA
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185
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Zaman MF, Nenadic A, Radojičić A, Rosado A, Beh CT. Sticking With It: ER-PM Membrane Contact Sites as a Coordinating Nexus for Regulating Lipids and Proteins at the Cell Cortex. Front Cell Dev Biol 2020; 8:675. [PMID: 32793605 PMCID: PMC7387695 DOI: 10.3389/fcell.2020.00675] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/03/2020] [Indexed: 12/31/2022] Open
Abstract
Membrane contact sites between the cortical endoplasmic reticulum (ER) and the plasma membrane (PM) provide a direct conduit for small molecule transfer and signaling between the two largest membranes of the cell. Contact is established through ER integral membrane proteins that physically tether the two membranes together, though the general mechanism is remarkably non-specific given the diversity of different tethering proteins. Primary tethers including VAMP-associated proteins (VAPs), Anoctamin/TMEM16/Ist2p homologs, and extended synaptotagmins (E-Syts), are largely conserved in most eukaryotes and are both necessary and sufficient for establishing ER-PM association. In addition, other species-specific ER-PM tether proteins impart unique functional attributes to both membranes at the cell cortex. This review distils recent functional and structural findings about conserved and species-specific tethers that form ER-PM contact sites, with an emphasis on their roles in the coordinate regulation of lipid metabolism, cellular structure, and responses to membrane stress.
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Affiliation(s)
- Mohammad F Zaman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Aleksa Nenadic
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Ana Radojičić
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.,Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Abel Rosado
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Christopher T Beh
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.,The Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC, Canada
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186
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Building a Bridge Between NMDAR-Mediated Excitotoxicity and Mitochondrial Dysfunction in Chronic and Acute Diseases. Cell Mol Neurobiol 2020; 41:1413-1430. [DOI: 10.1007/s10571-020-00924-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 07/13/2020] [Indexed: 02/07/2023]
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187
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Pleiotropic Mitochondria: The Influence of Mitochondria on Neuronal Development and Disease. J Neurosci 2020; 39:8200-8208. [PMID: 31619488 DOI: 10.1523/jneurosci.1157-19.2019] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/09/2019] [Accepted: 08/10/2019] [Indexed: 02/08/2023] Open
Abstract
Mitochondria play many important biological roles, including ATP production, lipid biogenesis, ROS regulation, and calcium clearance. In neurons, the mitochondrion is an essential organelle for metabolism and calcium homeostasis. Moreover, mitochondria are extremely dynamic and able to divide, fuse, and move along microtubule tracks to ensure their distribution to the neuronal periphery. Mitochondrial dysfunction and altered mitochondrial dynamics are observed in a wide range of conditions, from impaired neuronal development to various neurodegenerative diseases. Novel imaging techniques and genetic tools provide unprecedented access to the physiological roles of mitochondria by visualizing mitochondrial trafficking, morphological dynamics, ATP generation, and ultrastructure. Recent studies using these new techniques have unveiled the influence of mitochondria on axon branching, synaptic function, calcium regulation with the ER, glial cell function, neurogenesis, and neuronal repair. This review provides an overview of the crucial roles played by mitochondria in the CNS in physiological and pathophysiological conditions.
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188
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Farrell RJ, Ryan TA. Local Sourcing of Secretory Proteins in Faraway Places. Trends Neurosci 2020; 43:649-650. [PMID: 32546404 DOI: 10.1016/j.tins.2020.06.004] [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: 06/02/2020] [Accepted: 06/05/2020] [Indexed: 11/30/2022]
Abstract
A recent paper by Carter et al. identifies a novel organelle, the ribosome-associated vesicle (RAV), that might serve as a portable, local factory for producing proteins destined for the secretory pathway. The appearance of RAVs in dendrites suggests they may serve to generate membrane and secreted proteins in distal processes.
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Affiliation(s)
- Ryan J Farrell
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA; David Rockefeller Graduate Program, The Rockefeller University, New York, NY 10065, USA
| | - Timothy A Ryan
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA.
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189
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The mystery of mitochondria-ER contact sites in physiology and pathology: A cancer perspective. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165834. [PMID: 32437958 DOI: 10.1016/j.bbadis.2020.165834] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 04/29/2020] [Accepted: 05/01/2020] [Indexed: 12/13/2022]
Abstract
Mitochondria-associated membranes (MAM), physical platforms that enable communication between mitochondria and the endoplasmic reticulum (ER), are enriched with many proteins and enzymes involved in several crucial cellular processes, such as calcium (Ca2+) homeostasis, lipid synthesis and trafficking, autophagy and reactive oxygen species (ROS) production. Accumulating studies indicate that tumor suppressors and oncogenes are present at these intimate contacts between mitochondria and the ER, where they influence Ca2+ flux between mitochondria and the ER or affect lipid homeostasis at MAM, consequently impacting cell metabolism and cell fate. Understanding these fundamental roles of mitochondria-ER contact sites as important domains for tumor suppressors and oncogenes can support the search for new and more precise anticancer therapies. In the present review, we summarize the current understanding of basic MAM biology, composition and function and discuss the possible role of MAM-resident oncogenes and tumor suppressors.
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190
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Radler MR, Suber A, Spiliotis ET. Spatial control of membrane traffic in neuronal dendrites. Mol Cell Neurosci 2020; 105:103492. [PMID: 32294508 DOI: 10.1016/j.mcn.2020.103492] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/24/2020] [Accepted: 04/01/2020] [Indexed: 02/06/2023] Open
Abstract
Neuronal dendrites are highly branched and specialized compartments with distinct structures and secretory organelles (e.g., spines, Golgi outposts), and a unique cytoskeletal organization that includes microtubules of mixed polarity. Dendritic membranes are enriched with proteins, which specialize in the formation and function of the post-synaptic membrane of the neuronal synapse. How these proteins partition preferentially in dendrites, and how they traffic in a manner that is spatiotemporally accurate and regulated by synaptic activity are long-standing questions of neuronal cell biology. Recent studies have shed new insights into the spatial control of dendritic membrane traffic, revealing new classes of proteins (e.g., septins) and cytoskeleton-based mechanisms with dendrite-specific functions. Here, we review these advances by revisiting the fundamental mechanisms that control membrane traffic at the levels of protein sorting and motor-driven transport on microtubules and actin filaments. Overall, dendrites possess unique mechanisms for the spatial control of membrane traffic, which might have specialized and co-evolved with their highly arborized morphology.
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Affiliation(s)
- Megan R Radler
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA 19104, USA
| | - Ayana Suber
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA 19104, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA 19104, USA.
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191
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Lee CT, Laughlin JG, Angliviel de La Beaumelle N, Amaro RE, McCammon JA, Ramamoorthi R, Holst M, Rangamani P. 3D mesh processing using GAMer 2 to enable reaction-diffusion simulations in realistic cellular geometries. PLoS Comput Biol 2020; 16:e1007756. [PMID: 32251448 PMCID: PMC7162555 DOI: 10.1371/journal.pcbi.1007756] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 04/16/2020] [Accepted: 03/01/2020] [Indexed: 12/17/2022] Open
Abstract
Recent advances in electron microscopy have enabled the imaging of single cells in 3D at nanometer length scale resolutions. An uncharted frontier for in silico biology is the ability to simulate cellular processes using these observed geometries. Enabling such simulations requires watertight meshing of electron micrograph images into 3D volume meshes, which can then form the basis of computer simulations of such processes using numerical techniques such as the finite element method. In this paper, we describe the use of our recently rewritten mesh processing software, GAMer 2, to bridge the gap between poorly conditioned meshes generated from segmented micrographs and boundary marked tetrahedral meshes which are compatible with simulation. We demonstrate the application of a workflow using GAMer 2 to a series of electron micrographs of neuronal dendrite morphology explored at three different length scales and show that the resulting meshes are suitable for finite element simulations. This work is an important step towards making physical simulations of biological processes in realistic geometries routine. Innovations in algorithms to reconstruct and simulate cellular length scale phenomena based on emerging structural data will enable realistic physical models and advance discovery at the interface of geometry and cellular processes. We posit that a new frontier at the intersection of computational technologies and single cell biology is now open.
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Affiliation(s)
- Christopher T. Lee
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California, United States of America
| | - Justin G. Laughlin
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California, United States of America
| | - Nils Angliviel de La Beaumelle
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California, United States of America
| | - Rommie E. Amaro
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, United States of America
| | - J. Andrew McCammon
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, United States of America
| | - Ravi Ramamoorthi
- Department of Computer Science and Engineering, University of California, San Diego, La Jolla, California, United States of America
| | - Michael Holst
- Department of Mathematics, University of California, San Diego, La Jolla, California, United States of America
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California, United States of America
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192
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Huang X, Jiang C, Yu L, Yang A. Current and Emerging Approaches for Studying Inter-Organelle Membrane Contact Sites. Front Cell Dev Biol 2020; 8:195. [PMID: 32292782 PMCID: PMC7118198 DOI: 10.3389/fcell.2020.00195] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/09/2020] [Indexed: 12/24/2022] Open
Abstract
Inter-organelle membrane contact sites (MCSs) are classically defined as areas of close proximity between heterologous membranes and established by specific proteins (termed tethers). The interest on MCSs has rapidly increased in the last years, since MCSs play a crucial role in the transfer of cellular components between different organelles and have been involved in important cellular functions such as apoptosis, organelle division and biogenesis, and cell growth. Recently, an unprecedented depth and breadth in insights into the details of MCSs have been uncovered. On one hand, extensive MCSs (organelles interactome) are revealed by comprehensive analysis of organelle network with high temporal-spatial resolution at the system level. On the other hand, more and more tethers involving in MCSs are identified and further works are focusing on addressing the role of these tethers in regulating the function of MCSs at the molecular level. These enormous progresses largely depend on the powerful approaches, including several different types of microscopies and various biochemical techniques. These approaches have greatly accelerated recent advances in MCSs at the system and molecular level. In this review, we summarize the current and emerging approaches for studying MCSs, such as various microscopies, proximity-driven fluorescent signal generation and proximity-dependent biotinylation. In addition, we highlight the advantages and disadvantages of the techniques to provide a general guidance for the study of MCSs.
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Affiliation(s)
- Xue Huang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Chen Jiang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Lihua Yu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing, China
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193
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Cornejo VH, González C, Campos M, Vargas-Saturno L, Juricic MDLÁ, Miserey-Lenkei S, Pertusa M, Madrid R, Couve A. Non-conventional Axonal Organelles Control TRPM8 Ion Channel Trafficking and Peripheral Cold Sensing. Cell Rep 2020; 30:4505-4517.e5. [DOI: 10.1016/j.celrep.2020.03.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 10/07/2019] [Accepted: 03/05/2020] [Indexed: 12/31/2022] Open
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194
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Stephensen HJT, Darkner S, Sporring J. Restoring drifted electron microscope volumes using synaptic vesicles at sub-pixel accuracy. Commun Biol 2020; 3:81. [PMID: 32081999 PMCID: PMC7035423 DOI: 10.1038/s42003-020-0809-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 01/24/2020] [Indexed: 11/09/2022] Open
Abstract
Imaging ultrastructures in cells using Focused Ion Beam Scanning Electron Microscope (FIB-SEM) yields section-by-section images at nano-resolution. Unfortunately, we observe that FIB-SEM often introduces sub-pixel drifts between sections, in the order of 2.5 nm. The accumulation of these drifts significantly skews distance measures and geometric structures, which standard image registration techniques fail to correct. We demonstrate that registration techniques based on mutual information and sum-of-squared-distances significantly underestimate the drift since they are agnostic to image content. For neuronal data at nano-resolution, we discovered that vesicles serve as a statistically simple geometric structure, making them well-suited for estimating the drift with sub-pixel accuracy. Here, we develop a statistical model of vesicle shapes for drift correction, demonstrate its superiority, and provide a self-contained freely available application for estimating and correcting drifted datasets with vesicles.
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Affiliation(s)
| | - Sune Darkner
- Department of Computer Science, University of Copenhagen, Copenhagen, Denmark
| | - Jon Sporring
- Department of Computer Science, University of Copenhagen, Copenhagen, Denmark.
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195
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Endoplasmic reticulum-plasma membrane contacts: Principals of phosphoinositide and calcium signaling. Curr Opin Cell Biol 2020; 63:125-134. [PMID: 32088611 DOI: 10.1016/j.ceb.2020.01.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 01/18/2020] [Accepted: 01/20/2020] [Indexed: 12/29/2022]
Abstract
The endoplasmic reticulum (ER) forms an extensive network of membrane contact sites with intra-cellular organelles and the plasma membrane (PM). Interorganelle contacts have vital roles in membrane lipid and ion dynamics. In particular, ER-PM contacts are integral to numerous inter-cellular and intra-cellular signaling pathways including phosphoinositide lipid and calcium signaling, mechanotransduction, metabolic regulation, and cell stress responses. Accordingly, ER-PM contacts serve important signaling functions in excitable cells including neurons and muscle and endocrine cells. This review highlights recent advances in our understanding of the vital roles for ER-PM contacts in phosphoinositide and calcium signaling and how signaling pathways in turn regulate proteins that form and function at ER-PM contacts.
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196
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Lucke J, Kaltofen S, Hansson BS, Wicher D. The role of mitochondria in shaping odor responses in Drosophila melanogaster olfactory sensory neurons. Cell Calcium 2020; 87:102179. [PMID: 32070926 DOI: 10.1016/j.ceca.2020.102179] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/03/2020] [Accepted: 02/10/2020] [Indexed: 02/01/2023]
Abstract
Insects detect volatile chemosignals with olfactory sensory neurons (OSNs) that express olfactory receptors. Among them, the most sensitive receptors are the odorant receptors (ORs), which form cation channels passing also Ca2+. Here, we investigate if and how odor-induced Ca2+ signals in Drosophila melanogaster OSNs are controlled by intracellular Ca2+ stores, especially by mitochondria. Using an open antenna preparation that allows observation and pharmacological manipulation of OSNs we performed Ca2+ imaging to determine the role of Ca2+ influx and efflux pathways in OSN mitochondria. The results indicate that mitochondria participate in shaping the OR responses. The major players of this modulation are the mitochondrial Ca2+ uniporter and the mitochondrial permeability transition pore. Intriguingly, OR-induced Ca2+ signals were only mildly affected by modulating the Ca2+ management of the endoplasmic reticulum.
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Affiliation(s)
- Jan Lucke
- Max Planck Institute for Chemical Ecology, Department of Evolutionary Neuroethology, Hans-Knöll- Str. 8, D-07745 Jena, Germany
| | - Sabine Kaltofen
- Max Planck Institute for Chemical Ecology, Department of Evolutionary Neuroethology, Hans-Knöll- Str. 8, D-07745 Jena, Germany
| | - Bill S Hansson
- Max Planck Institute for Chemical Ecology, Department of Evolutionary Neuroethology, Hans-Knöll- Str. 8, D-07745 Jena, Germany
| | - Dieter Wicher
- Max Planck Institute for Chemical Ecology, Department of Evolutionary Neuroethology, Hans-Knöll- Str. 8, D-07745 Jena, Germany.
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197
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Öztürk Z, O’Kane CJ, Pérez-Moreno JJ. Axonal Endoplasmic Reticulum Dynamics and Its Roles in Neurodegeneration. Front Neurosci 2020; 14:48. [PMID: 32116502 PMCID: PMC7025499 DOI: 10.3389/fnins.2020.00048] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/13/2020] [Indexed: 12/13/2022] Open
Abstract
The physical continuity of axons over long cellular distances poses challenges for their maintenance. One organelle that faces this challenge is endoplasmic reticulum (ER); unlike other intracellular organelles, this forms a physically continuous network throughout the cell, with a single membrane and a single lumen. In axons, ER is mainly smooth, forming a tubular network with occasional sheets or cisternae and low amounts of rough ER. It has many potential roles: lipid biosynthesis, glucose homeostasis, a Ca2+ store, protein export, and contacting and regulating other organelles. This tubular network structure is determined by ER-shaping proteins, mutations in some of which are causative for neurodegenerative disorders such as hereditary spastic paraplegia (HSP). While axonal ER shares many features with the tubular ER network in other contexts, these features must be adapted to the long and narrow dimensions of axons. ER appears to be physically continuous throughout axons, over distances that are enormous on a subcellular scale. It is therefore a potential channel for long-distance or regional communication within neurons, independent of action potentials or physical transport of cargos, but involving its physiological roles such as Ca2+ or organelle homeostasis. Despite its apparent stability, axonal ER is highly dynamic, showing features like anterograde and retrograde transport, potentially reflecting continuous fusion and breakage of the network. Here we discuss the transport processes that must contribute to this dynamic behavior of ER. We also discuss the model that these processes underpin a homeostatic process that ensures both enough ER to maintain continuity of the network and repair breaks in it, but not too much ER that might disrupt local cellular physiology. Finally, we discuss how failure of ER organization in axons could lead to axon degenerative diseases, and how a requirement for ER continuity could make distal axons most susceptible to degeneration in conditions that disrupt ER continuity.
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Affiliation(s)
| | - Cahir J. O’Kane
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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198
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Vasan R, Rowan MP, Lee CT, Johnson GR, Rangamani P, Holst M. Applications and Challenges of Machine Learning to Enable Realistic Cellular Simulations. FRONTIERS IN PHYSICS 2020; 7:247. [PMID: 36188416 PMCID: PMC9521042 DOI: 10.3389/fphy.2019.00247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In this perspective, we examine three key aspects of an end-to-end pipeline for realistic cellular simulations: reconstruction and segmentation of cellular structures; generation of cellular structures; and mesh generation, simulation, and data analysis. We highlight some of the relevant prior work in these distinct but overlapping areas, with a particular emphasis on current use of machine learning technologies, as well as on future opportunities.
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Affiliation(s)
- Ritvik Vasan
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, United States
| | - Meagan P. Rowan
- Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Christopher T. Lee
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, United States
| | | | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, United States
| | - Michael Holst
- Department of Mathematics, University of California San Diego, La Jolla, CA, United States
- Department of Physics, University of California San Diego, La Jolla, CA, United States
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199
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Lakpa KL, Halcrow PW, Chen X, Geiger JD. Readily Releasable Stores of Calcium in Neuronal Endolysosomes: Physiological and Pathophysiological Relevance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:681-697. [PMID: 31646530 PMCID: PMC7047846 DOI: 10.1007/978-3-030-12457-1_27] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Neurons are long-lived post-mitotic cells that possess an elaborate system of endosomes and lysosomes (endolysosomes) for protein quality control. Relatively recently, endolysosomes were recognized to contain high concentrations (400-600 μM) of readily releasable calcium. The release of calcium from this acidic organelle store contributes to calcium-dependent processes of fundamental physiological importance to neurons including neurotransmitter release, membrane excitability, neurite outgrowth, synaptic remodeling, and cell viability. Pathologically, disturbances of endolysosome structure and/or function have been noted in a variety of neurodegenerative disorders including Alzheimer's disease (AD) and HIV-1 associated neurocognitive disorder (HAND). And, dysregulation of intracellular calcium has been implicated in the neuropathogenesis of these same neurological disorders. Thus, it is important to better understand mechanisms by which calcium is released from endolysosomes as well as the consequences of such release to inter-organellar signaling, physiological functions of neurons, and possible pathological consequences. In doing so, a path forward towards new therapeutic modalities might be facilitated.
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Affiliation(s)
- Koffi L Lakpa
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Peter W Halcrow
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Xuesong Chen
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Jonathan D Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA.
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200
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Vallese F, Barazzuol L, Maso L, Brini M, Calì T. ER-Mitochondria Calcium Transfer, Organelle Contacts and Neurodegenerative Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:719-746. [PMID: 31646532 DOI: 10.1007/978-3-030-12457-1_29] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
It is generally accepted that interorganellar contacts are central to the control of cellular physiology. Virtually, any intracellular organelle can come into proximity with each other and, by establishing physical protein-mediated contacts within a selected fraction of the membrane surface, novel specific functions are acquired. Endoplasmic reticulum (ER) contacts with mitochondria are among the best studied and have a major role in Ca2+ and lipid transfer, signaling, and membrane dynamics.Their functional (and structural) diversity, their dynamic nature as well as the growing number of new players involved in the tethering concurred to make their monitoring difficult especially in living cells. This review focuses on the most established examples of tethers/modulators of the ER-mitochondria interface and on the roles of these contacts in health and disease by specifically dissecting how Ca2+ transfer occurs and how mishandling eventually leads to disease. Additional functions of the ER-mitochondria interface and an overview of the currently available methods to measure/quantify the ER-mitochondria interface will also be discussed.
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Affiliation(s)
- Francesca Vallese
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Lucia Barazzuol
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Lorenzo Maso
- Department of Biology, University of Padua, Padua, Italy
| | - Marisa Brini
- Department of Biology, University of Padua, Padua, Italy.
| | - Tito Calì
- Department of Biomedical Sciences, University of Padua, Padua, Italy. .,Padua Neuroscience Center (PNC), Padua, Italy.
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