1
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Knippenberg S, De K, Aisenbrey C, Bechinger B, Osella S. Hydration- and Temperature-Dependent Fluorescence Spectra of Laurdan Conformers in a DPPC Membrane. Cells 2024; 13:1232. [PMID: 39120265 PMCID: PMC11311969 DOI: 10.3390/cells13151232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Revised: 07/18/2024] [Accepted: 07/20/2024] [Indexed: 08/10/2024] Open
Abstract
The widely used Laurdan probe has two conformers, resulting in different optical properties when embedded in a lipid bilayer membrane, as demonstrated by our previous simulations. Up to now, the two conformers' optical responses have, however, not been investigated when the temperature and the phase of the membrane change. Since Laurdan is known to be both a molecular rotor and a solvatochromic probe, it is subject to a profound interaction with both neighboring lipids and water molecules. In the current study, molecular dynamics simulations and hybrid Quantum Mechanics/Molecular Mechanics calculations are performed for a DPPC membrane at eight temperatures between 270K and 320K, while the position, orientation, fluorescence lifetime and fluorescence anisotropy of the embedded probes are monitored. The importance of both conformers is proven through a stringent comparison with experiments, which corroborates the theoretical findings. It is seen that for Conf-I, the excited state lifetime is longer than the relaxation of the environment, while for Conf-II, the surroundings are not yet adapted when the probe returns to the ground state. Throughout the temperature range, the lifetime and anisotropy decay curves can be used to identify the different membrane phases. The current work might, therefore, be of importance for biomedical studies on diseases, which are associated with cell membrane transformations.
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Affiliation(s)
- Stefan Knippenberg
- Theory Lab, Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium
| | - Kathakali De
- Institut de Chimie de Strasbourg, University of Strasbourg/CNRS, UMR7177, rue Blaise Pascal, F-67008 Strasbourg, France; (K.D.)
| | - Christopher Aisenbrey
- Institut de Chimie de Strasbourg, University of Strasbourg/CNRS, UMR7177, rue Blaise Pascal, F-67008 Strasbourg, France; (K.D.)
| | - Burkhard Bechinger
- Institut de Chimie de Strasbourg, University of Strasbourg/CNRS, UMR7177, rue Blaise Pascal, F-67008 Strasbourg, France; (K.D.)
| | - Silvio Osella
- Chemical and Biological Systems Simulation Lab, Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland
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2
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Lipowsky R. Multiscale remodeling of biomembranes and vesicles. Methods Enzymol 2024; 701:175-236. [PMID: 39025572 DOI: 10.1016/bs.mie.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Biomembranes and vesicles cover a wide range of length scales. Indeed, small nanovesicles have a diameter of a few tens of nanometers whereas giant vesicles can have diameters up to hundreds of micrometers. The remodeling of giant vesicles on the micron scale can be observed by light microscopy and understood by the theory of curvature elasticity, which represents a top-down approach. The theory predicts the formation of multispherical shapes as recently observed experimentally. On the nanometer scale, much insight has been obtained via coarse-grained molecular dynamics simulations of nanovesicles, which provides a bottom-up approach based on the lipid numbers assembled in the two bilayer leaflets and the resulting leaflet tensions. The remodeling processes discussed here include the shape transformations of vesicles, their morphological responses to the adhesion of condensate droplets, the instabilities of lipid bilayers and nanovesicles, as well as the topological transformations of vesicles by membrane fission and fusion. The latter processes determine the complex topology of the endoplasmic reticulum.
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Affiliation(s)
- Reinhard Lipowsky
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany.
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3
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Crapart CC, Scott ZC, Konno T, Sharma A, Parutto P, Bailey DMD, Westrate LM, Avezov E, Koslover EF. Luminal transport through intact endoplasmic reticulum limits the magnitude of localized Ca 2+ signals. Proc Natl Acad Sci U S A 2024; 121:e2312172121. [PMID: 38502705 PMCID: PMC10990089 DOI: 10.1073/pnas.2312172121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 02/09/2024] [Indexed: 03/21/2024] Open
Abstract
The endoplasmic reticulum (ER) forms an interconnected network of tubules stretching throughout the cell. Understanding how ER functionality relies on its structural organization is crucial for elucidating cellular vulnerability to ER perturbations, which have been implicated in several neuronal pathologies. One of the key functions of the ER is enabling Ca[Formula: see text] signaling by storing large quantities of this ion and releasing it into the cytoplasm in a spatiotemporally controlled manner. Through a combination of physical modeling and live-cell imaging, we demonstrate that alterations in ER shape significantly impact its ability to support efficient local Ca[Formula: see text] releases, due to hindered transport of luminal content within the ER. Our model reveals that rapid Ca[Formula: see text] release necessitates mobile luminal buffer proteins with moderate binding strength, moving through a well-connected network of ER tubules. These findings provide insight into the functional advantages of normal ER architecture, emphasizing its importance as a kinetically efficient intracellular Ca[Formula: see text] delivery system.
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Affiliation(s)
- Cécile C. Crapart
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | | | - Tasuku Konno
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Aman Sharma
- Department of Physics, University of California, San Diego, La Jolla, CA92130
| | - Pierre Parutto
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - David M. D. Bailey
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Laura M. Westrate
- Department of Chemistry and Biochemistry, Calvin University, Grand Rapids, MI49546
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Elena F. Koslover
- Department of Physics, University of California, San Diego, La Jolla, CA92130
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4
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Monterroso B, Margolin W, Boersma AJ, Rivas G, Poolman B, Zorrilla S. Macromolecular Crowding, Phase Separation, and Homeostasis in the Orchestration of Bacterial Cellular Functions. Chem Rev 2024; 124:1899-1949. [PMID: 38331392 PMCID: PMC10906006 DOI: 10.1021/acs.chemrev.3c00622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 12/01/2023] [Accepted: 01/10/2024] [Indexed: 02/10/2024]
Abstract
Macromolecular crowding affects the activity of proteins and functional macromolecular complexes in all cells, including bacteria. Crowding, together with physicochemical parameters such as pH, ionic strength, and the energy status, influences the structure of the cytoplasm and thereby indirectly macromolecular function. Notably, crowding also promotes the formation of biomolecular condensates by phase separation, initially identified in eukaryotic cells but more recently discovered to play key functions in bacteria. Bacterial cells require a variety of mechanisms to maintain physicochemical homeostasis, in particular in environments with fluctuating conditions, and the formation of biomolecular condensates is emerging as one such mechanism. In this work, we connect physicochemical homeostasis and macromolecular crowding with the formation and function of biomolecular condensates in the bacterial cell and compare the supramolecular structures found in bacteria with those of eukaryotic cells. We focus on the effects of crowding and phase separation on the control of bacterial chromosome replication, segregation, and cell division, and we discuss the contribution of biomolecular condensates to bacterial cell fitness and adaptation to environmental stress.
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Affiliation(s)
- Begoña Monterroso
- Department
of Structural and Chemical Biology, Centro de Investigaciones Biológicas
Margarita Salas, Consejo Superior de Investigaciones
Científicas (CSIC), 28040 Madrid, Spain
| | - William Margolin
- Department
of Microbiology and Molecular Genetics, McGovern Medical School, UTHealth-Houston, Houston, Texas 77030, United States
| | - Arnold J. Boersma
- Cellular
Protein Chemistry, Bijvoet Centre for Biomolecular Research, Faculty
of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Germán Rivas
- Department
of Structural and Chemical Biology, Centro de Investigaciones Biológicas
Margarita Salas, Consejo Superior de Investigaciones
Científicas (CSIC), 28040 Madrid, Spain
| | - Bert Poolman
- Department
of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Silvia Zorrilla
- Department
of Structural and Chemical Biology, Centro de Investigaciones Biológicas
Margarita Salas, Consejo Superior de Investigaciones
Científicas (CSIC), 28040 Madrid, Spain
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5
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Zhang W, Zhang Z, Xiang Y, Gu DD, Chen J, Chen Y, Zhai S, Liu Y, Jiang T, Liu C, He B, Yan M, Wang Z, Xu J, Cao YL, Deng B, Zeng D, Lei J, Zhuo J, Lei X, Long Z, Jin B, Chen T, Li D, Shen Y, Hu J, Gao S, Liu Q. Aurora kinase A-mediated phosphorylation triggers structural alteration of Rab1A to enhance ER complexity during mitosis. Nat Struct Mol Biol 2024; 31:219-231. [PMID: 38177680 DOI: 10.1038/s41594-023-01165-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/26/2023] [Indexed: 01/06/2024]
Abstract
Morphological rearrangement of the endoplasmic reticulum (ER) is critical for metazoan mitosis. Yet, how the ER is remodeled by the mitotic signaling remains unclear. Here, we report that mitotic Aurora kinase A (AURKA) employs a small GTPase, Rab1A, to direct ER remodeling. During mitosis, AURKA phosphorylates Rab1A at Thr75. Structural analysis demonstrates that Thr75 phosphorylation renders Rab1A in a constantly active state by preventing interaction with GDP-dissociation inhibitor (GDI). Activated Rab1A is retained on the ER and induces the oligomerization of ER-shaping protein RTNs and REEPs, eventually triggering an increase of ER complexity. In various models, from Caenorhabditis elegans and Drosophila to mammals, inhibition of Rab1AThr75 phosphorylation by genetic modifications disrupts ER remodeling. Thus, our study reveals an evolutionarily conserved mechanism explaining how mitotic kinase controls ER remodeling and uncovers a critical function of Rab GTPases in metaphase.
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Affiliation(s)
- Wei Zhang
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
- Department of Clinical Immunology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Zijian Zhang
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Yun Xiang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dong-Dong Gu
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Jinna Chen
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Yifan Chen
- University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Shixian Zhai
- MOE Key Laboratory of Laser Life Science and College of Biophotonics, South China Normal University, Guangzhou, China
| | - Yong Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Tao Jiang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chong Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Bin He
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Min Yan
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Zifeng Wang
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Jie Xu
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Yu-Lu Cao
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Bing Deng
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Deshun Zeng
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Jie Lei
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Junxiao Zhuo
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Xinxing Lei
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Zijie Long
- Department of Hematology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Institute of Hematology, Sun Yat-sen University, Guangzhou, China
| | - Bilian Jin
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Tongsheng Chen
- MOE Key Laboratory of Laser Life Science and College of Biophotonics, South China Normal University, Guangzhou, China
| | - Dong Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yidong Shen
- University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Junjie Hu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
| | - Song Gao
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China.
| | - Quentin Liu
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China.
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China.
- Institute of Hematology, Sun Yat-sen University, Guangzhou, China.
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6
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Griffing LR. Dancing with the Stars: Using Image Analysis to Study the Choreography of the Endoplasmic Reticulum and Its Partners and of Movement Within Its Tubules. Methods Mol Biol 2024; 2772:87-114. [PMID: 38411808 DOI: 10.1007/978-1-0716-3710-4_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
In this chapter, approaches to the image analysis of the choreography of the plant endoplasmic reticulum (ER) labeled with fluorescent fusion proteins ("stars," if you wish) are presented. The approaches include the analyses of those parts of the ER that are attached through membrane contact sites to moving or non-moving partners (other "stars"). Image analysis is also used to understand the nature of the tubular polygonal network, the hallmark of this organelle, and how the polygons change over time due to tubule sliding or motion. Furthermore, the remodeling polygons of the ER interact with regions of fundamentally different topologies, the ER cisternae, and image analysis can be used to separate the tubules from the cisternae. ER cisternae, like polygons and tubules, can be motile or stationary. To study which parts are attached to non-moving partners, such as domains of the ER that form membrane contact sites with the plasma membrane/cell wall, an image analysis approach called persistency mapping has been used. To study the domains of the ER that move rapidly and stream through the cell, image analysis of optic flow has been used. However, optic flow approaches confuse the movement of the ER itself with the movement of proteins within the ER. As an overall measure of ER dynamics, optic flow approaches are of value, but their limitation as to what exactly is "flowing" needs to be specified. Finally, there are important imaging approaches that directly address the movement of fluorescent proteins within the ER lumen or in the membrane of the ER. Of these, fluorescence recovery after photobleaching (FRAP), inverse FRAP (iFRAP), and single particle tracking approaches are described.
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7
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Kenworthy AK. What's past is prologue: FRAP keeps delivering 50 years later. Biophys J 2023; 122:3577-3586. [PMID: 37218127 PMCID: PMC10541474 DOI: 10.1016/j.bpj.2023.05.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/03/2023] [Accepted: 05/11/2023] [Indexed: 05/24/2023] Open
Abstract
Fluorescence recovery after photobleaching (FRAP) has emerged as one of the most widely utilized techniques to quantify binding and diffusion kinetics of biomolecules in biophysics. Since its inception in the mid-1970s, FRAP has been used to address an enormous array of questions including the characteristic features of lipid rafts, how cells regulate the viscosity of their cytoplasm, and the dynamics of biomolecules inside condensates formed by liquid-liquid phase separation. In this perspective, I briefly summarize the history of the field and discuss why FRAP has proven to be so incredibly versatile and popular. Next, I provide an overview of the extensive body of knowledge that has emerged on best practices for quantitative FRAP data analysis, followed by some recent examples of biological lessons learned using this powerful approach. Finally, I touch on new directions and opportunities for biophysicists to contribute to the continued development of this still-relevant research tool.
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Affiliation(s)
- Anne K Kenworthy
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia.
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8
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Lipowsky R, Pramanik S, Benk AS, Tarnawski M, Spatz JP, Dimova R. Elucidating the Morphology of the Endoplasmic Reticulum: Puzzles and Perspectives. ACS NANO 2023. [PMID: 37377213 DOI: 10.1021/acsnano.3c01338] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Artificial or synthetic organelles are a key challenge for bottom-up synthetic biology. So far, synthetic organelles have typically been based on spherical membrane compartments, used to spatially confine selected chemical reactions. In vivo, these compartments are often far from being spherical and can exhibit rather complex architectures. A particularly fascinating example is provided by the endoplasmic reticulum (ER), which extends throughout the whole cell by forming a continuous network of membrane nanotubes connected by three-way junctions. The nanotubes have a typical diameter of between 50 and 100 nm. In spite of much experimental progress, several fundamental aspects of the ER morphology remain elusive. A long-standing puzzle is the straight appearance of the tubules in the light microscope, which form irregular polygons with contact angles close to 120°. Another puzzling aspect is the nanoscopic shapes of the tubules and junctions, for which very different images have been obtained by electron microcopy and structured illumination microscopy. Furthermore, both the formation and maintenance of the reticular networks require GTP and GTP-hydrolyzing membrane proteins. In fact, the networks are destroyed by the fragmentation of nanotubes when the supply of GTP is interrupted. Here, it is argued that all of these puzzling observations are intimately related to each other and to the dimerization of two membrane proteins anchored to the same membrane. So far, the functional significance of this dimerization process remained elusive and, thus, seemed to waste a lot of GTP. However, this process can generate an effective membrane tension that stabilizes the irregular polygonal geometry of the reticular networks and prevents the fragmentation of their tubules, thereby maintaining the integrity of the ER. By incorporating the GTP-hydrolyzing membrane proteins into giant unilamellar vesicles, the effective membrane tension will become accessible to systematic experimental studies.
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Affiliation(s)
- Reinhard Lipowsky
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Shreya Pramanik
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Amelie S Benk
- Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | | | - Joachim P Spatz
- Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
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9
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Weiß M, Hernandez LC, Gil Montoya DC, Löhndorf A, Krüger A, Kopdag M, Uebler L, Landwehr M, Nawrocki M, Huber S, Woelk LM, Werner R, Failla AV, Flügel A, Dupont G, Guse AH, Diercks BP. Adhesion to laminin-1 and collagen IV induces the formation of Ca 2+ microdomains that sensitize mouse T cells for activation. Sci Signal 2023; 16:eabn9405. [PMID: 37339181 DOI: 10.1126/scisignal.abn9405] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Accepted: 05/31/2023] [Indexed: 06/22/2023]
Abstract
During an immune response, T cells migrate from blood vessel walls into inflamed tissues by migrating across the endothelium and through extracellular matrix (ECM). Integrins facilitate T cell binding to endothelial cells and ECM proteins. Here, we report that Ca2+ microdomains observed in the absence of T cell receptor (TCR)/CD3 stimulation are initial signaling events triggered by adhesion to ECM proteins that increase the sensitivity of primary murine T cells to activation. Adhesion to the ECM proteins collagen IV and laminin-1 increased the number of Ca2+ microdomains in a manner dependent on the kinase FAK, phospholipase C (PLC), and all three inositol 1,4,5-trisphosphate receptor (IP3R) subtypes and promoted the nuclear translocation of the transcription factor NFAT-1. Mathematical modeling predicted that the formation of adhesion-dependent Ca2+ microdomains required the concerted activity of two to six IP3Rs and ORAI1 channels to achieve the increase in the Ca2+ concentration in the ER-plasma membrane junction that was observed experimentally and that required SOCE. Further, adhesion-dependent Ca2+ microdomains were important for the magnitude of the TCR-induced activation of T cells on collagen IV as assessed by the global Ca2+ response and NFAT-1 nuclear translocation. Thus, adhesion to collagen IV and laminin-1 sensitizes T cells through a mechanism involving the formation of Ca2+ microdomains, and blocking this low-level sensitization decreases T cell activation upon TCR engagement.
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Affiliation(s)
- Mariella Weiß
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Lola C Hernandez
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Diana C Gil Montoya
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Anke Löhndorf
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Aileen Krüger
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Miriam Kopdag
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Liana Uebler
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Marie Landwehr
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Mikolaj Nawrocki
- Section of Molecular Immunology und Gastroenterology, I. Department of Medicine, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Samuel Huber
- Section of Molecular Immunology und Gastroenterology, I. Department of Medicine, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Lena-Marie Woelk
- Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - René Werner
- Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Antonio V Failla
- Microscopy Imaging Facility (UMIF), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Alexander Flügel
- Institute for Neuroimmunology and Multiple Sclerosis Research, University Medical Centre Göttingen, 37075 Göttingen, Germany
| | - Geneviève Dupont
- Unité de Chronobiologie Théorique, Faculté des Sciences, CP231, Université Libre de Bruxelles (ULB), B-1050 Brussels, Belgium
| | - Andreas H Guse
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Björn-Philipp Diercks
- Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
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10
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Armoza-Eilat S, Malis Y, Caspi M, Shomron O, Hirschberg K, Rosin-Arbesfeld R. Title: The C-terminal amphipathic helix of Carboxypeptidase E mediates export from the ER and secretion via lysosomes. J Mol Biol 2023:168171. [PMID: 37285900 DOI: 10.1016/j.jmb.2023.168171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/09/2023]
Abstract
Carboxypeptidase E (CPE), an essential enzyme in the biosynthetic production line of most peptide hormones and neuropeptides, is predominantly expressed in endocrine tissues and in the nervous system. CPE is active in acidic environments where it cleaves the C'-terminal basic residues of peptide precursors to generate their bioactive form. Consequently, this highly conserved enzyme regulates numerous fundamental biological processes. Here, we combined live-cell microscopy and molecular analysis to examine the intracellular distribution and secretion dynamics of fluorescently tagged CPE. We show that, in non-endocrine cells, tagged-CPE is a soluble luminal protein that is efficiently exported from the ER via the Golgi apparatus to lysosomes. The C'-terminal conserved amphipathic helix serves as a lysosomal and secretory granule targeting and a secretion motif. Following secretion, CPE may be reinternalized into the lysosomes of neighboring cells.
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Affiliation(s)
- Shir Armoza-Eilat
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yehonathan Malis
- Department of Pathology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Michal Caspi
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Olga Shomron
- Department of Pathology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Koret Hirschberg
- Department of Pathology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Rina Rosin-Arbesfeld
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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11
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Ivanova A, Atakpa-Adaji P. Phosphatidylinositol 4,5-bisphosphate and calcium at ER-PM junctions - Complex interplay of simple messengers. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119475. [PMID: 37098393 DOI: 10.1016/j.bbamcr.2023.119475] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 03/05/2023] [Accepted: 04/03/2023] [Indexed: 04/27/2023]
Abstract
Endoplasmic reticulum-plasma membrane contact sites (ER-PM MCS) are a specialised domain involved in the control of Ca2+ dynamics and various Ca2+-dependent cellular processes. Intracellular Ca2+ signals are broadly supported by Ca2+ release from intracellular Ca2+ channels such as inositol 1,4,5-trisphosphate receptors (IP3Rs) and subsequent store-operated Ca2+ entry (SOCE) across the PM to replenish store content. IP3Rs sit in close proximity to the PM where they can easily access newly synthesised IP3, interact with binding partners such as actin, and localise adjacent to ER-PM MCS populated by the SOCE machinery, STIM1-2 and Orai1-3, to possibly form a locally regulated unit of Ca2+ influx. PtdIns(4,5)P2 is a multiplex regulator of Ca2+ signalling at the ER-PM MCS interacting with multiple proteins at these junctions such as actin and STIM1, whilst also being consumed as a substrate for phospholipase C to produce IP3 in response to extracellular stimuli. In this review, we consider the mechanisms regulating the synthesis and turnover of PtdIns(4,5)P2 via the phosphoinositide cycle and its significance for sustained signalling at the ER-PM MCS. Furthermore, we highlight recent insights into the role of PtdIns(4,5)P2 in the spatiotemporal organization of signalling at ER-PM junctions and raise outstanding questions on how this multi-faceted regulation occurs.
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Affiliation(s)
- Adelina Ivanova
- Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, UK.
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12
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Xiang L, Yan R, Chen K, Li W, Xu K. Single-Molecule Displacement Mapping Unveils Sign-Asymmetric Protein Charge Effects on Intraorganellar Diffusion. NANO LETTERS 2023; 23:1711-1716. [PMID: 36802676 PMCID: PMC10044514 DOI: 10.1021/acs.nanolett.2c04379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Using single-molecule displacement/diffusivity mapping (SMdM), an emerging super-resolution microscopy method, here we quantify, at nanoscale resolution, the diffusion of a typical fluorescent protein (FP) in the endoplasmic reticulum (ER) and mitochondrion of living mammalian cells. We thus show that the diffusion coefficients D in both organelles are ∼40% of that in the cytoplasm, with the latter exhibiting higher spatial inhomogeneities. Moreover, we unveil that diffusions in the ER lumen and the mitochondrial matrix are markedly impeded when the FP is given positive, but not negative, net charges. Calculation shows most intraorganellar proteins as negatively charged, hence a mechanism to impede the diffusion of positively charged proteins. However, we further identify the ER protein PPIB as an exception with a positive net charge and experimentally show that the removal of this positive charge elevates its intra-ER diffusivity. We thus unveil a sign-asymmetric protein charge effect on the nanoscale intraorganellar diffusion.
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Affiliation(s)
- Limin Xiang
- Department of Chemistry & California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA, 94720
- College of Chemistry and Molecular Sciences & TaiKang Center for Life and Medical Sciences, Wuhan University, Wuhan 430072, China
| | - Rui Yan
- Department of Chemistry & California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA, 94720
| | - Kun Chen
- Department of Chemistry & California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA, 94720
| | - Wan Li
- Department of Chemistry & California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA, 94720
| | - Ke Xu
- Department of Chemistry & California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA, 94720
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13
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Campbell EP, Abushawish AA, Valdez LA, Bell MK, Haryono M, Rangamani P, Bloodgood BL. Electrical signals in the ER are cell type and stimulus specific with extreme spatial compartmentalization in neurons. Cell Rep 2023; 42:111943. [PMID: 36640310 PMCID: PMC10033362 DOI: 10.1016/j.celrep.2022.111943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 10/04/2022] [Accepted: 12/15/2022] [Indexed: 01/06/2023] Open
Abstract
The endoplasmic reticulum (ER) is a tortuous organelle that spans throughout a cell with a continuous membrane containing ion channels, pumps, and transporters. It is unclear if stimuli that gate ER ion channels trigger substantial membrane potential fluctuations and if those fluctuations spread beyond their site of origin. Here, we visualize ER membrane potential dynamics in HEK cells and cultured rat hippocampal neurons by targeting a genetically encoded voltage indicator specifically to the ER membrane. We report the existence of clear cell-type- and stimulus-specific ER membrane potential fluctuations. In neurons, direct stimulation of ER ryanodine receptors generates depolarizations that scale linearly with stimulus strength and reach tens of millivolts. However, ER potentials do not spread beyond the site of receptor activation, exhibiting steep attenuation that is exacerbated by intracellular large conductance K+ channels. Thus, segments of ER can generate large depolarizations that are actively restricted from impacting nearby, contiguous membrane.
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Affiliation(s)
- Evan P Campbell
- Neurobiology Department, School of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Ahmed A Abushawish
- Neurobiology Department, School of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Lauren A Valdez
- Neurobiology Department, School of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Miriam K Bell
- Department of Mechanical and Aerospace Engineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Melita Haryono
- Neurobiology Department, School of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Brenda L Bloodgood
- Neurobiology Department, School of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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14
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Xiang L, Yan R, Chen K, Li W, Xu K. Single-molecule displacement mapping unveils sign-asymmetric protein charge effects on intraorganellar diffusion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.26.525611. [PMID: 36747807 PMCID: PMC9900983 DOI: 10.1101/2023.01.26.525611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Using single-molecule displacement/diffusivity mapping (SM d M), an emerging super-resolution microscopy method, here we quantify, at nanoscale resolution, the diffusion of a typical fluorescent protein (FP) in the endoplasmic reticulum (ER) and mitochondrion of living mammalian cells. We thus show that the diffusion coefficients D in both organelles are ~40% of that in the cytoplasm, with the latter exhibiting higher spatial inhomogeneities. Moreover, we unveil that diffusions in the ER lumen and the mitochondrial matrix are markedly impeded when the FP is given positive, but not negative, net charges. Calculation shows most intraorganellar proteins as negatively charged, thus a mechanism to impede the diffusion of positively charged proteins. However, we further identify the ER protein PPIB as an exception with a positive net charge, and experimentally show that the removal of this positive charge elevates its intra-ER diffusivity. We thus unveil a sign-asymmetric protein charge effect on the nanoscale intraorganellar diffusion.
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15
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Sánchez-Vázquez VH, Martínez-Martínez E, Gallegos-Gómez ML, Arias JM, Pallafacchina G, Rizzuto R, Guerrero-Hernández A. Heterogeneity of the endoplasmic reticulum Ca 2+ store determines colocalization with mitochondria. Cell Calcium 2023; 109:102688. [PMID: 36538845 DOI: 10.1016/j.ceca.2022.102688] [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: 06/13/2022] [Revised: 11/14/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022]
Abstract
Contact sites between the endoplasmic reticulum (ER) and mitochondria play a pivotal role in cell signaling, and the interaction between these organelles is dynamic and finely regulated. We have studied the role of ER Ca2+ concentration ([Ca2+]ER) in modulating this association in HeLa and HEK293 cells and human fibroblasts. According to Manders' coefficient, ER-mitochondria colocalization varied depending on the ER marker; it was the highest with ER-Tracker and the lowest with ER Ca2+ indicators (Mag-Fluo-4, erGAP3, and G-CEPIA1er) in both HeLa cells and human fibroblasts. Only GEM-CEPIA1er displayed a high colocalization with elongated mitochondria in HeLa cells, this ER Ca2+ indicator reveals low Ca2+ regions because this ion quenches its fluorescence. On the contrary, the typical rounded and fragmented mitochondria of HEK293 cells colocalized with Mag-Fluo-4 and, to a lesser extent, with GEM-CEPIA1er. The ablation of the three IP3R isoforms in HEK293 cells increased mitochondria-GEM-CEPIA1er colocalization. This pattern of colocalization was inversely correlated with the rate of ER Ca2+ leak evoked by thapsigargin (Tg). Moreover, Tg and Histamine in the absence of external Ca2+ increased mitochondria-ER colocalization. On the contrary, in the presence of external Ca2+, both Bafilomycin A1 and Tg reduced the mitochondria-ER interaction. Notably, knocking down MCU decreased mitochondria-ER colocalization. Overall, our data suggest that the [Ca2+] is not homogenous within the ER lumen and that mitochondria-ER interaction is modulated by the ER Ca2+ leak and the [Ca2+]i.
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Affiliation(s)
| | | | | | - Juan M Arias
- Programa de Neurociencias-UIICSE, Facultad de Estudios Superiores Iztacala, UNAM; Tlalnepantla de Baz, Estado de México, 54090, Mexico
| | - Giorgia Pallafacchina
- CNR, Neuroscience Institute, Padua, 35131. Italy; Department of Biomedical Sciences, University of Padua, Padua, 35131. Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, Padua, 35131. Italy
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16
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Saito T, Matsunaga D, Deguchi S. Analysis of chemomechanical behavior of stress fibers by continuum mechanics-based FRAP. Biophys J 2022; 121:2921-2930. [PMID: 35778840 PMCID: PMC9388576 DOI: 10.1016/j.bpj.2022.06.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 06/07/2022] [Accepted: 06/27/2022] [Indexed: 11/18/2022] Open
Abstract
Fluorescence recovery after photobleaching (FRAP) is a common technique to analyze the turnover of molecules in living cells. Numerous physicochemical models have been developed to quantitatively evaluate the rate of turnover driven by chemical reaction and diffusion that occurs in a few seconds to minutes. On the other hand, they have limitations in interpreting long-term FRAP responses where intracellular active movement inevitably provides target molecular architectures with additional effects other than chemical reaction and diffusion, namely directed transport and structural deformation. To overcome the limitations, we develop a continuum mechanics-based model that allows for decoupling FRAP response into the intrinsic turnover rate and subcellular mechanical characteristics such as displacement vector and strain tensor. Our approach was validated using fluorescently labeled β-actin in an actomyosin-mediated contractile apparatus called stress fibers, revealing spatially distinct patterns of the multi-physicochemical events, in which the turnover rate, which represents effective off-rate of β-actin, was significantly higher at the center of the cell. We also found that the turnover rate is negatively correlated with the rate of displacement or velocity along stress fibers but, interestingly, not with the absolute magnitude of strain. Moreover, stress fibers are subjected to centripetal flow that is facilitated by the circulation of actin molecules. Taken together, this novel framework for long-term FRAP analysis allows for unveiling the contribution of overlooked microscopic mechanics to molecular turnover in living cells.
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Affiliation(s)
- Takumi Saito
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan; Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan.
| | - Daiki Matsunaga
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Shinji Deguchi
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.
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17
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Cai N, Lai ACK, Liao K, Corridon PR, Graves DJ, Chan V. Recent Advances in Fluorescence Recovery after Photobleaching for Decoupling Transport and Kinetics of Biomacromolecules in Cellular Physiology. Polymers (Basel) 2022; 14:1913. [PMID: 35567083 PMCID: PMC9105003 DOI: 10.3390/polym14091913] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/27/2022] [Accepted: 04/29/2022] [Indexed: 12/16/2022] Open
Abstract
Among the new molecular tools available to scientists and engineers, some of the most useful include fluorescently tagged biomolecules. Tools, such as green fluorescence protein (GFP), have been applied to perform semi-quantitative studies on biological signal transduction and cellular structural dynamics involved in the physiology of healthy and disease states. Such studies focus on drug pharmacokinetics, receptor-mediated endocytosis, nuclear mechanobiology, viral infections, and cancer metastasis. In 1976, fluorescence recovery after photobleaching (FRAP), which involves the monitoring of fluorescence emission recovery within a photobleached spot, was developed. FRAP allowed investigators to probe two-dimensional (2D) diffusion of fluorescently-labelled biomolecules. Since then, FRAP has been refined through the advancements of optics, charged-coupled-device (CCD) cameras, confocal microscopes, and molecular probes. FRAP is now a highly quantitative tool used for transport and kinetic studies in the cytosol, organelles, and membrane of a cell. In this work, the authors intend to provide a review of recent advances in FRAP. The authors include epifluorescence spot FRAP, total internal reflection (TIR)/FRAP, and confocal microscope-based FRAP. The underlying mathematical models are also described. Finally, our understanding of coupled transport and kinetics as determined by FRAP will be discussed and the potential for future advances suggested.
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Affiliation(s)
- Ning Cai
- Wuhan Institute of Technology, School of Chemical Engineering and Pharmacy, Wuhan 430073, China;
| | - Alvin Chi-Keung Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong 999077, China;
| | - Kin Liao
- Department of Aerospace Engineering, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates;
| | - Peter R. Corridon
- Department of Physiology and Immunology, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates;
- Healthcare Engineering Innovation Center, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
| | - David J. Graves
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA;
| | - Vincent Chan
- Department of Biomedical Engineering, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
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18
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Magni A, Bondelli G, Paternò GM, Sardar S, Sesti V, D'Andrea C, Bertarelli C, Lanzani G. Azobenzene photoisomerization probes cell membrane viscosity. Phys Chem Chem Phys 2022; 24:8716-8723. [PMID: 35373231 DOI: 10.1039/d1cp05881a] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The viscosity of cell membranes is a crucial parameter that affects the diffusion of small molecules both across and within the lipid membrane and that is related to several diseases. Therefore, the possibility to measure quantitatively membrane viscosity on the nanoscale is of great interest. Here, we report a complete investigation of the photophysics of an amphiphilic membrane-targeted azobenzene (ZIAPIN2) and we propose its use as a viscosity probe for cell membranes. We exploit ZIAPIN2 trans-cis photoisomerization to develop a molecular viscometer and to assess the viscosity of Escherichia coli bacteria membranes employing time-resolved fluorescence spectroscopy. Fluorescence lifetime measurements of ZIAPIN2 in E. coli bacteria suspensions correctly indicate that the membrane viscosity decreases as the temperature of the sample increases. Given the non-homogeneity and the anisotropy of cell membranes, as supported by the photophysical characterization of the probe within the lipid bilayer, we shed new light on the intricate membrane rheology.
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Affiliation(s)
- Arianna Magni
- Dipartimento di Fisica, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy. .,Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70, 20133, Milano, Italy
| | - Gaia Bondelli
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70, 20133, Milano, Italy
| | - Giuseppe M Paternò
- Dipartimento di Fisica, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy. .,Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70, 20133, Milano, Italy
| | - Samim Sardar
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70, 20133, Milano, Italy
| | - Valentina Sesti
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70, 20133, Milano, Italy.,Dipartimento di Chimica, Materiali e Ingegneria Chimica 'Giulio Natta', Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy
| | - Cosimo D'Andrea
- Dipartimento di Fisica, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy. .,Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70, 20133, Milano, Italy
| | - Chiara Bertarelli
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70, 20133, Milano, Italy.,Dipartimento di Chimica, Materiali e Ingegneria Chimica 'Giulio Natta', Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy
| | - Guglielmo Lanzani
- Dipartimento di Fisica, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy. .,Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70, 20133, Milano, Italy
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19
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Chambers JE, Zubkov N, Kubánková M, Nixon-Abell J, Mela I, Abreu S, Schwiening M, Lavarda G, López-Duarte I, Dickens JA, Torres T, Kaminski CF, Holt LJ, Avezov E, Huntington JA, George-Hyslop PS, Kuimova MK, Marciniak SJ. Z-α 1-antitrypsin polymers impose molecular filtration in the endoplasmic reticulum after undergoing phase transition to a solid state. SCIENCE ADVANCES 2022; 8:eabm2094. [PMID: 35394846 PMCID: PMC8993113 DOI: 10.1126/sciadv.abm2094] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/16/2022] [Indexed: 05/06/2023]
Abstract
Misfolding of secretory proteins in the endoplasmic reticulum (ER) features in many human diseases. In α1-antitrypsin deficiency, the pathogenic Z variant aberrantly assembles into polymers in the hepatocyte ER, leading to cirrhosis. We show that α1-antitrypsin polymers undergo a liquid:solid phase transition, forming a protein matrix that retards mobility of ER proteins by size-dependent molecular filtration. The Z-α1-antitrypsin phase transition is promoted during ER stress by an ATF6-mediated unfolded protein response. Furthermore, the ER chaperone calreticulin promotes Z-α1-antitrypsin solidification and increases protein matrix stiffness. Single-particle tracking reveals that solidification initiates in cells with normal ER morphology, previously assumed to represent a healthy pool. We show that Z-α1-antitrypsin-induced hypersensitivity to ER stress can be explained by immobilization of ER chaperones within the polymer matrix. This previously unidentified mechanism of ER dysfunction provides a template for understanding a diverse group of related proteinopathies and identifies ER chaperones as potential therapeutic targets.
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Affiliation(s)
- Joseph E. Chambers
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Nikita Zubkov
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Markéta Kubánková
- Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, UK
| | - Jonathon Nixon-Abell
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Ioanna Mela
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
| | - Susana Abreu
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Max Schwiening
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Giulia Lavarda
- Departamento de Química Orgánica and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Ismael López-Duarte
- Departamento de Química Orgánica and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Jennifer A. Dickens
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Tomás Torres
- Departamento de Química Orgánica and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Madrid 28049, Spain
- IMDEA Nanociencia, Campus de Cantoblanco, Madrid 28049, Spain
| | - Clemens F. Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
| | - Liam J. Holt
- Institute for Systems Genetics, New York University Grossman School of Medicine, 435 E 30th St, New York, NY 10016, USA
| | - Edward Avezov
- Department of Clinical Neurosciences and UK Dementia Research Institute, University of Cambridge, Cambridge CB2 0AH, UK
| | - James A. Huntington
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
| | - Peter St George-Hyslop
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
- Department of Medicine (Neurology), Temerty Faculty of Medicine, University of Toronto, University Health Network, Toronto, ON M5T 0S8, Canada
- Taub Institute For Research on Alzheimer’s Disease and the Ageing Brain, Department of Neurology, Columbia University Irvine Medical Center, 630 West 1/68 Street, New York, NY 10032, USA
| | - Marina K. Kuimova
- Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, UK
| | - Stefan J. Marciniak
- Cambridge Institute for Medical Research (CIMR), Department of Medicine, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, UK
- Royal Papworth Hospital, Cambridge CB2 0AY, UK
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20
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Seiler DK, Hay JC. Genetically encoded fluorescent tools: Shining a little light on ER-to-Golgi transport. Free Radic Biol Med 2022; 183:14-24. [PMID: 35272000 PMCID: PMC9097910 DOI: 10.1016/j.freeradbiomed.2022.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 03/03/2022] [Accepted: 03/05/2022] [Indexed: 12/11/2022]
Abstract
Since the first fluorescent proteins (FPs) were identified and isolated over fifty years ago, FPs have become commonplace yet indispensable tools for studying the constitutive secretory pathway in live cells. At the same time, genetically encoded chemical tags have provided a new use for much older fluorescent dyes. Innovation has also produced several specialized methods to allow synchronous release of cargo proteins from the endoplasmic reticulum (ER), enabling precise characterization of sequential trafficking steps in the secretory pathway. Without the constant innovation of the researchers who design these tools to control, image, and quantitate protein secretion, major discoveries about ER-to-Golgi transport and later stages of the constitutive secretory pathway would not have been possible. We review many of the tools and tricks, some 25 years old and others brand new, that have been successfully implemented to study ER-to-Golgi transport in intact and living cells.
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Affiliation(s)
- Danette Kowal Seiler
- Division of Biological Sciences, Center for Structural & Functional Neuroscience, University of Montana, Missoula, MT, 59812, USA
| | - Jesse C Hay
- Division of Biological Sciences, Center for Structural & Functional Neuroscience, University of Montana, Missoula, MT, 59812, USA.
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21
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Abstract
Fluorescent tools have emerged as an important tool for studying the distinct chemical microenvironments of organelles, due to their high specificity and ability to be used in non-destructive, live cellular studies. These tools fall largely in two categories: exogenous fluorescent dyes, or endogenous labels such as genetically encoded fluorescent proteins. In both cases, the probe must be targeted to the organelle of interest. To date, many organelle-targeted fluorescent tools have been reported and used to uncover new information about processes that underpin health and disease. However, the majority of these tools only apply a handful of targeting groups, and less-studied organelles have few robust targeting strategies. While the development of new, robust strategies is difficult, it is essential to develop such strategies to allow for the development of new tools and broadening the effective study of organelles. This review aims to provide a comprehensive overview of the major targeting strategies for both endogenous and exogenous fluorescent cargo, outlining the specific challenges for targeting each organelle type and as well as new developments in the field.
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Affiliation(s)
- Jiarun Lin
- School of Chemistry, The University of Sydney, NSW, 2006, Australia.
- The University of Sydney Nano Institute (Sydney Nano), The University of Sydney, NSW 2006, Australia
| | - Kylie Yang
- School of Chemistry, The University of Sydney, NSW, 2006, Australia.
| | - Elizabeth J New
- School of Chemistry, The University of Sydney, NSW, 2006, Australia.
- The University of Sydney Nano Institute (Sydney Nano), The University of Sydney, NSW 2006, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, NSW 2006, Australia
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22
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Agarwala PK, Aneja R, Kapoor S. Lipidomic landscape in cancer: Actionable insights for membrane-based therapy and diagnoses. Med Res Rev 2021; 42:983-1018. [PMID: 34719798 DOI: 10.1002/med.21868] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 08/18/2021] [Accepted: 10/24/2021] [Indexed: 01/17/2023]
Abstract
Cancer cells display altered cellular lipid metabolism, including disruption in endogenous lipid synthesis, storage, and exogenous uptake for membrane biogenesis and functions. Altered lipid metabolism and, consequently, lipid composition impacts cellular function by affecting membrane structure and properties, such as fluidity, rigidity, membrane dynamics, and lateral organization. Herein, we provide an overview of lipid membranes and how their properties affect cellular functions. We also detail how the rewiring of lipid metabolism impacts the lipidomic landscape of cancer cell membranes and influences the characteristics of cancer cells. Furthermore, we discuss how the altered cancer lipidome provides cues for developing lipid-inspired innovative therapeutic and diagnostic strategies while improving our limited understanding of the role of lipids in cancer initiation and progression. We also present the arcade of membrane characterization techniques to cement their relevance in cancer diagnosis and monitoring of treatment response.
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Affiliation(s)
- Prema K Agarwala
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India
| | - Ritu Aneja
- Department of Biology, Georgia State University, Atlanta, Georgia, USA
| | - Shobhna Kapoor
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India.,Depertment of Biofunctional Science and Technology, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
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Intertwined and Finely Balanced: Endoplasmic Reticulum Morphology, Dynamics, Function, and Diseases. Cells 2021; 10:cells10092341. [PMID: 34571990 PMCID: PMC8472773 DOI: 10.3390/cells10092341] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/02/2021] [Accepted: 09/04/2021] [Indexed: 02/07/2023] Open
Abstract
The endoplasmic reticulum (ER) is an organelle that is responsible for many essential subcellular processes. Interconnected narrow tubules at the periphery and thicker sheet-like regions in the perinuclear region are linked to the nuclear envelope. It is becoming apparent that the complex morphology and dynamics of the ER are linked to its function. Mutations in the proteins involved in regulating ER structure and movement are implicated in many diseases including neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and amyotrophic lateral sclerosis (ALS). The ER is also hijacked by pathogens to promote their replication. Bacteria such as Legionella pneumophila and Chlamydia trachomatis, as well as the Zika virus, bind to ER morphology and dynamics-regulating proteins to exploit the functions of the ER to their advantage. This review covers our understanding of ER morphology, including the functional subdomains and membrane contact sites that the organelle forms. We also focus on ER dynamics and the current efforts to quantify ER motion and discuss the diseases related to ER morphology and dynamics.
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24
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Abstract
Bleb-driven cell migration plays important roles in diverse biological processes. Here, we present the mechanism for polarity establishment and maintenance in blebbing cells in vivo. We show that actin polymerization defines the leading edge, the position where blebs form. We show that the cell front can direct the formation of the rear by facilitating retrograde flow of proteins that limit the generation of blebs at the opposite aspect of the cell. Conversely, localization of bleb-inhibiting proteins at one aspect of the cell results in the establishment of the cell front at the opposite side. These antagonistic interactions result in robust polarity that can be initiated in a random direction, or oriented by a chemokine gradient. To study the mechanisms controlling front-rear polarity in migrating cells, we used zebrafish primordial germ cells (PGCs) as an in vivo model. We find that polarity of bleb-driven migrating cells can be initiated at the cell front, as manifested by actin accumulation at the future leading edge and myosin-dependent retrograde actin flow toward the other side of the cell. In such cases, the definition of the cell front, from which bleb-inhibiting proteins such as Ezrin are depleted, precedes the establishment of the cell rear, where those proteins accumulate. Conversely, following cell division, the accumulation of Ezrin at the cleavage plane is the first sign for cell polarity and this aspect of the cell becomes the cell back. Together, the antagonistic interactions between the cell front and back lead to a robust polarization of the cell. Furthermore, we show that chemokine signaling can bias the establishment of the front-rear axis of the cell, thereby guiding the migrating cells toward sites of higher levels of the attractant. We compare these results to a theoretical model according to which a critical value of actin treadmilling flow can initiate a positive feedback loop that leads to the generation of the front-rear axis and to stable cell polarization. Together, our in vivo findings and the mathematical model, provide an explanation for the observed nonoriented migration of primordial germ cells in the absence of the guidance cue, as well as for the directed migration toward the region where the gonad develops.
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25
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Aalto A, Olguin-Olguin A, Raz E. Zebrafish Primordial Germ Cell Migration. Front Cell Dev Biol 2021; 9:684460. [PMID: 34249937 PMCID: PMC8260996 DOI: 10.3389/fcell.2021.684460] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/17/2021] [Indexed: 01/03/2023] Open
Abstract
Similar to many other organisms, zebrafish primordial germ cells (PGCs) are specified at a location distinct from that of gonadal somatic cells. Guided by chemotactic cues, PGCs migrate through embryonic tissues toward the region where the gonad develops. In this process, PGCs employ a bleb-driven amoeboid migration mode, characterized by low adhesion and high actomyosin contractility, a strategy used by other migrating cells, such as leukocytes and certain types of cancer cells. The mechanisms underlying the motility and the directed migration of PGCs should be robust to ensure arrival at the target, thereby contributing to the fertility of the organism. These features make PGCs an excellent model for studying guided single-cell migration in vivo. In this review, we present recent findings regarding the establishment and maintenance of cell polarity that are essential for motility and discuss the mechanisms by which cell polarization and directed migration are controlled by chemical and physical cues.
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Affiliation(s)
- Anne Aalto
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany
| | - Adan Olguin-Olguin
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany
| | - Erez Raz
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany
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26
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Ivchenkov DV, Kuzmin PI, Galimzyanov TR, Shnyrova AV, Bashkirov PV, Frolov VA. Nonlinear material and ionic transport through membrane nanotubes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183677. [PMID: 34118214 DOI: 10.1016/j.bbamem.2021.183677] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 06/07/2021] [Indexed: 11/29/2022]
Abstract
Membrane nanotubes (NTs) and their networks play an important role in intracellular membrane transport and intercellular communications. The transport characteristics of the NT lumen resemble those of conventional solid-state nanopores. However, unlike the rigid pores, the soft membrane wall of the NT can be deformed by forces driving the transport through the NT lumen. This intrinsic coupling between the NT geometry and transport properties remains poorly explored. Using synchronized fluorescence microscopy and conductance measurements, we revealed that the NT shape was changed by both electric and hydrostatic forces driving the ionic and solute fluxes through the NT lumen. Far from the shape instability, the strength of the force effect is determined by the lateral membrane tension and is scaled with membrane elasticity so that the NT can be operated as a linear elastic sensor. Near shape instabilities, the transport forces triggered large-scale shape transformations, both stochastic and periodic. The periodic oscillations were coupled to a vesicle passage along the NT axis, resembling peristaltic transport. The oscillations were parametrically controlled by the electric field, making NT a highly nonlinear nanofluidic circuitry element with biological and technological implications.
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Affiliation(s)
- D V Ivchenkov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow 119435, Russia; Department of Molecular and Biological Physics, Moscow Institute of Physics and Technology, Institutskiy lane 9, Dolgoprudnyy, Moskow region 141700, Russia
| | - P I Kuzmin
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow 119071, Russia
| | - T R Galimzyanov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow 119071, Russia
| | - A V Shnyrova
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, barrio Sarriena s/n, 48940 Leioa, Spain; Department of Biochemistry and Molecular Biology, University of the Basque Country, barrio Sarriena s/n, 48940 Leioa, Spain
| | - P V Bashkirov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow 119435, Russia; Department of Molecular and Biological Physics, Moscow Institute of Physics and Technology, Institutskiy lane 9, Dolgoprudnyy, Moskow region 141700, Russia.
| | - V A Frolov
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, barrio Sarriena s/n, 48940 Leioa, Spain; Department of Biochemistry and Molecular Biology, University of the Basque Country, barrio Sarriena s/n, 48940 Leioa, Spain; Ikerbasque, Basque Foundation for Science, Maria Diaz de Haro 3, 6 solairua, 48013 Bilbao, Spain.
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27
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Determining the domain-level reaction-diffusion properties of an actin-binding protein transgelin-2 within cells. Exp Cell Res 2021; 404:112619. [PMID: 33965400 DOI: 10.1016/j.yexcr.2021.112619] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/18/2021] [Accepted: 04/19/2021] [Indexed: 11/21/2022]
Abstract
Proteins in cells undergo repeated binding to other molecules, thereby reducing the apparent extent of their intracellular diffusion. While much effort has been made to analytically decouple these combined effects of pure diffusion and chemical binding, it is difficult with conventional approaches to attribute the measured quantities to the nature of specific domains of the proteins. Motivated by the common goal in cell signaling research aimed at identifying the domains responsible for particular intermolecular interactions, here we describe a framework for determining the local physicochemical properties of cellular proteins associated with immobile scaffolds. To validate this new approach, we apply it to transgelin-2, an actin-binding protein whose intracellular dynamics remains elusive. We develop a fluorescence recovery after photobleaching (FRAP)-based framework, in which comprehensive combinations of domain-deletion mutants are created, and the difference among them in FRAP response is analyzed. We demonstrate that transgelin-2 in actin stress fibers (SFs) interacts with F-actin via two separate domains, and the chemical properties are determined for the individual domains. Its pure diffusion properties independent of the association to F-actin is also obtained. Our approach will thus be useful, as presented here for transgelin-2, in addressing the signaling mechanism of cellular proteins associated with SFs.
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28
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Gil D, Guse AH, Dupont G. Three-Dimensional Model of Sub-Plasmalemmal Ca 2+ Microdomains Evoked by the Interplay Between ORAI1 and InsP 3 Receptors. Front Immunol 2021; 12:659790. [PMID: 33995380 PMCID: PMC8113648 DOI: 10.3389/fimmu.2021.659790] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/06/2021] [Indexed: 11/21/2022] Open
Abstract
Ca2+ signaling plays an essential role in T cell activation, which is a key step to start an adaptive immune response. During the transition from a quiescent to a fully activated state, Ca2+ microdomains characterized by reduced spatial and temporal extents are observed in the junctions between the plasma membrane (PM) and the endoplasmic reticulum (ER). Such Ca2+ responses can also occur in response to T cell adhesion to other cells or extracellular matrix proteins in otherwise unstimulated T cells. These non-TCR/CD3-dependent Ca2+ microdomains rely on d-myo-inositol 1,4,5-trisphosphate (IP3) signaling and subsequent store operated Ca2+ entry (SOCE) via the ORAI/STIM system. The detailed molecular mechanism of adhesion-dependent Ca2+ microdomain formation remains to be fully elucidated. We used mathematical modeling to investigate the spatiotemporal characteristics of T cell Ca2+ microdomains and their molecular regulators. We developed a reaction-diffusion model using COMSOL Multiphysics to describe the evolution of cytosolic and ER Ca2+ concentrations in a three-dimensional ER-PM junction. Equations are based on a previously proposed realistic description of the junction, which is extended to take into account IP3 receptors (IP3R) that are located next to the junction. The first model only considered the ORAI channels and the SERCA pumps. Taking into account the existence of preformed clusters of ORAI1 and STIM2, ORAI1 slightly opens in conditions of a full ER. These simulated Ca2+ microdomains are too small as compared to those observed in unstimulated T cells. When considering the opening of the IP3Rs located near the junction, the local depletion of ER Ca2+ allows for larger Ca2+ fluxes through the ORAI1 channels and hence larger local Ca2+ concentrations. Computational results moreover show that Ca2+ diffusion in the ER has a major impact on the Ca2+ changes in the junction, by affecting the local Ca2+ gradients in the sub-PM ER. Besides pointing out the likely involvement of the spontaneous openings of IP3Rs in the activation of SOCE in conditions of T cell adhesion prior to full activation, the model provides a tool to investigate how Ca2+ microdomains extent and interact in response to T cell receptor activation.
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Affiliation(s)
- Diana Gil
- The Ca2+ Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas H Guse
- The Ca2+ Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Geneviève Dupont
- Unit of Theoretical Chronobiology, Faculté des Sciences CP231, Université Libre de Bruxelles (ULB), Brussels, Belgium
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29
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Castro-Sánchez P, Hernández-Pérez S, Aguilar-Sopeña O, Ramírez-Muñoz R, Rodríguez-Perales S, Torres-Ruiz R, Roda-Navarro P. Fast Diffusion Sustains Plasma Membrane Accumulation of Phosphatase of Regenerating Liver-1. Front Cell Dev Biol 2021; 8:585842. [PMID: 33425892 PMCID: PMC7793866 DOI: 10.3389/fcell.2020.585842] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 11/16/2020] [Indexed: 11/13/2022] Open
Abstract
It has been proposed that the accumulation of farnesylated phosphatase of regenerating liver-1 (PRL-1) at the plasma membrane is mediated by static electrostatic interactions of a polybasic region with acidic membrane lipids and assisted by oligomerization. Nonetheless, localization at early and recycling endosomes suggests that the recycling compartment might also contribute to its plasma membrane accumulation. Here, we investigated in live cells the dynamics of PRL-1 fused to the green fluorescent protein (GFP-PRL-1). Blocking the secretory pathway and photobleaching techniques suggested that plasma membrane accumulation of PRL-1 was not sustained by recycling endosomes but by a dynamic exchange of diffusible protein pools. Consistent with this idea, fluorescence correlation spectroscopy in cells overexpressing wild type or monomeric mutants of GFP-PRL-1 measured cytosolic and membrane-diffusing pools of protein that were not dependent on oligomerization. Endogenous expression of GFP-PRL-1 by CRISPR/Cas9 genome edition confirmed the existence of fast diffusing cytosolic and membrane pools of protein. We propose that plasma membrane PRL-1 replenishment is independent of the recycling compartment and the oligomerization state and mainly driven by fast diffusion of the cytosolic pool.
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Affiliation(s)
- Patricia Castro-Sánchez
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Universidad Complutense de Madrid and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Sara Hernández-Pérez
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Universidad Complutense de Madrid and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Oscar Aguilar-Sopeña
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Universidad Complutense de Madrid and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Rocia Ramírez-Muñoz
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Universidad Complutense de Madrid and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Sandra Rodríguez-Perales
- Molecular Cytogenetics and Genome Editing Unit, Human Cancer Genetics Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain
| | - Raúl Torres-Ruiz
- Molecular Cytogenetics and Genome Editing Unit, Human Cancer Genetics Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain
| | - Pedro Roda-Navarro
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Universidad Complutense de Madrid and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
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30
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S Mogre S, Brown AI, Koslover EF. Getting around the cell: physical transport in the intracellular world. Phys Biol 2020; 17:061003. [PMID: 32663814 DOI: 10.1088/1478-3975/aba5e5] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Eukaryotic cells face the challenging task of transporting a variety of particles through the complex intracellular milieu in order to deliver, distribute, and mix the many components that support cell function. In this review, we explore the biological objectives and physical mechanisms of intracellular transport. Our focus is on cytoplasmic and intra-organelle transport at the whole-cell scale. We outline several key biological functions that depend on physically transporting components across the cell, including the delivery of secreted proteins, support of cell growth and repair, propagation of intracellular signals, establishment of organelle contacts, and spatial organization of metabolic gradients. We then review the three primary physical modes of transport in eukaryotic cells: diffusive motion, motor-driven transport, and advection by cytoplasmic flow. For each mechanism, we identify the main factors that determine speed and directionality. We also highlight the efficiency of each transport mode in fulfilling various key objectives of transport, such as particle mixing, directed delivery, and rapid target search. Taken together, the interplay of diffusion, molecular motors, and flows supports the intracellular transport needs that underlie a broad variety of biological phenomena.
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Affiliation(s)
- Saurabh S Mogre
- Department of Physics, University of California, San Diego, San Diego, California 92093, United States of America
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31
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Kashirina AS, López-Duarte I, Kubánková M, Gulin AA, Dudenkova VV, Rodimova SA, Torgomyan HG, Zagaynova EV, Meleshina AV, Kuimova MK. Monitoring membrane viscosity in differentiating stem cells using BODIPY-based molecular rotors and FLIM. Sci Rep 2020; 10:14063. [PMID: 32820221 PMCID: PMC7441180 DOI: 10.1038/s41598-020-70972-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/29/2020] [Indexed: 11/09/2022] Open
Abstract
Membrane fluidity plays an important role in many cell functions such as cell adhesion, and migration. In stem cell lines membrane fluidity may play a role in differentiation. Here we report the use of viscosity-sensitive fluorophores based on a BODIPY core, termed “molecular rotors”, in combination with Fluorescence Lifetime Imaging Microscopy, for monitoring of plasma membrane viscosity changes in mesenchymal stem cells (MSCs) during osteogenic and chondrogenic differentiation. In order to correlate the viscosity values with membrane lipid composition, the detailed analysis of the corresponding membrane lipid composition of differentiated cells was performed by time-of-flight secondary ion mass spectrometry. Our results directly demonstrate for the first time that differentiation of MSCs results in distinct membrane viscosities, that reflect the change in lipidome of the cells following differentiation.
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Affiliation(s)
- Alena S Kashirina
- Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Sq., Nizhny Novgorod, Russian Federation, 603950
| | - Ismael López-Duarte
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, London, W12 0BZ, UK
| | - Markéta Kubánková
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, London, W12 0BZ, UK
| | - Alexander A Gulin
- N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences (FRCCP RAS), Kosygin st. 4, Moscow, Russian Federation, 119991.,Department of Chemistry, Lomonosov Moscow State University, Leninskiye Gory 1-3, Moscow, Russian Federation, 119991
| | - Varvara V Dudenkova
- Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Sq., Nizhny Novgorod, Russian Federation, 603950
| | - Svetlana A Rodimova
- Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Sq., Nizhny Novgorod, Russian Federation, 603950.,Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, Novgorod, Nizhny Novgorod, Russian Federation, 603950
| | - Hayk G Torgomyan
- Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Sq., Nizhny Novgorod, Russian Federation, 603950
| | - Elena V Zagaynova
- Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Sq., Nizhny Novgorod, Russian Federation, 603950.,Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, Novgorod, Nizhny Novgorod, Russian Federation, 603950
| | - Aleksandra V Meleshina
- Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Sq., Nizhny Novgorod, Russian Federation, 603950.
| | - Marina K Kuimova
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, London, W12 0BZ, UK.
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32
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Back to the Future: Genetically Encoded Fluorescent Proteins as Inert Tracers of the Intracellular Environment. Int J Mol Sci 2020; 21:ijms21114164. [PMID: 32545175 PMCID: PMC7312867 DOI: 10.3390/ijms21114164] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/09/2020] [Accepted: 06/09/2020] [Indexed: 01/08/2023] Open
Abstract
Over the past decades, the discovery and development of genetically encoded fluorescent proteins (FPs) has brought a revolution into our ability to study biologic phenomena directly within living matter. First, FPs enabled fluorescence-labeling of a variety of molecules of interest to study their localization, interactions and dynamic behavior at various scales-from cells to whole organisms/animals. Then, rationally engineered FP-based sensors facilitated the measurement of physicochemical parameters of living matter-especially at the intracellular level, such as ion concentration, temperature, viscosity, pressure, etc. In addition, FPs were exploited as inert tracers of the intracellular environment in which they are expressed. This oft-neglected role is made possible by two distinctive features of FPs: (i) the quite null, unspecific interactions of their characteristic β-barrel structure with the molecular components of the cellular environment; and (ii) their compatibility with the use of time-resolved fluorescence-based optical microscopy techniques. This review seeks to highlight the potential of such unique combinations of properties and report on the most significative and original applications (and related advancements of knowledge) produced to date. It is envisioned that the use of FPs as inert tracers of living matter structural organization holds a potential for several lines of further development in the next future, discussed in the last section of the review, which in turn can lead to new breakthroughs in bioimaging.
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33
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Role of the nuclear membrane protein Emerin in front-rear polarity of the nucleus. Nat Commun 2020; 11:2122. [PMID: 32358486 PMCID: PMC7195445 DOI: 10.1038/s41467-020-15910-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 04/02/2020] [Indexed: 12/03/2022] Open
Abstract
Cell polarity refers to the intrinsic asymmetry of cells, including the orientation of the cytoskeleton. It affects cell shape and structure as well as the distribution of proteins and organelles. In migratory cells, front-rear polarity is essential and dictates movement direction. While the link between the cytoskeleton and nucleus is well-studied, we aim to investigate if front-rear polarity can be transmitted to the nucleus. We show that the knock-down of emerin, an integral protein of the nuclear envelope, abolishes preferential localization of several nuclear proteins. We propose that the frontally biased localization of the endoplasmic reticulum, through which emerin reaches the nuclear envelope, is sufficient to generate its observed bias. In primary emerin-deficient myoblasts, its expression partially rescues the polarity of the nucleus. Our results demonstrate that front-rear cell polarity is transmitted to the nucleus and that emerin is an important determinant of nuclear polarity. During cell migration, cells are polarized with distinct front vs. rear regions but whether and how polarity is transmitted to the nucleus is unclear. Here the authors show that frontally-biased endoplasmic reticulum and the nuclear membrane protein Emerin contribute to front-rear nuclear cell polarity.
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34
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Impact of global structure on diffusive exploration of organelle networks. Sci Rep 2020; 10:4984. [PMID: 32188905 PMCID: PMC7080787 DOI: 10.1038/s41598-020-61598-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 02/25/2020] [Indexed: 01/08/2023] Open
Abstract
We investigate diffusive search on planar networks, motivated by tubular organelle networks in cell biology that contain molecules searching for reaction partners and binding sites. Exact calculation of the diffusive mean first-passage time on a spatial network is used to characterize the typical search time as a function of network connectivity. We find that global structural properties — the total edge length and number of loops — are sufficient to largely determine network exploration times for a variety of both synthetic planar networks and organelle morphologies extracted from living cells. For synthetic networks on a lattice, we predict the search time dependence on these global structural parameters by connecting with percolation theory, providing a bridge from irregular real-world networks to a simpler physical model. The dependence of search time on global network structural properties suggests that network architecture can be designed for efficient search without controlling the precise arrangement of connections. Specifically, increasing the number of loops substantially decreases search times, pointing to a potential physical mechanism for regulating reaction rates within organelle network structures.
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35
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Ponce W, Cordero ML. Local details versus effective medium approximation: A study of diffusion in microfluidic random networks made from Voronoi tessellations. Phys Rev E 2020; 101:023110. [PMID: 32168582 DOI: 10.1103/physreve.101.023110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 02/11/2020] [Indexed: 11/07/2022]
Abstract
We measured the effective diffusion coefficient in regions of microfluidic networks of controlled geometry using the fluorescence recovery after photobleaching (FRAP) technique. The geometry of the networks was based on Voronoi tessellations, and had varying characteristic length scale and porosity. For a fixed network, FRAP experiments were performed in regions of increasing size. Our results indicate that the boundary of the bleached region, and in particular the cumulative area of the channels that connect the bleached region to the rest of the network, are important in the measured value of the effective diffusion coefficient. We found that the statistical geometrical variations between different regions of the network decrease with the size of the bleached region as a power law, meaning that the statistical error of effective medium approximations decrease with the size of the studied medium with no characteristic length scale.
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Affiliation(s)
- Washington Ponce
- Departamento de Ciencias Exactas, Universidad de las Fuerzas Armadas ESPE - Extensión Santo Domingo, Vía Santo Domingo - Quevedo km. 24, Santo Domingo, Ecuador
| | - María Luisa Cordero
- Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago, Chile
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36
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Cadar AG, Feaster TK, Bersell KR, Wang L, Hong T, Balsamo JA, Zhang Z, Chun YW, Nam YJ, Gotthardt M, Knollmann BC, Roden DM, Lim CC, Hong CC. Real-time visualization of titin dynamics reveals extensive reversible photobleaching in human induced pluripotent stem cell-derived cardiomyocytes. Am J Physiol Cell Physiol 2020; 318:C163-C173. [PMID: 31747312 PMCID: PMC6985833 DOI: 10.1152/ajpcell.00107.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 11/08/2019] [Accepted: 11/08/2019] [Indexed: 12/17/2022]
Abstract
Fluorescence recovery after photobleaching (FRAP) has been useful in delineating cardiac myofilament biology, and innovations in fluorophore chemistry have expanded the array of microscopic assays used. However, one assumption in FRAP is the irreversible photobleaching of fluorescent proteins after laser excitation. Here we demonstrate reversible photobleaching regarding the photoconvertible fluorescent protein mEos3.2. We used CRISPR/Cas9 genome editing in human induced pluripotent stem cells (hiPSCs) to knock-in mEos3.2 into the COOH terminus of titin to visualize sarcomeric titin incorporation and turnover. Upon cardiac induction, the titin-mEos3.2 fusion protein is expressed and integrated in the sarcomeres of hiPSC-derived cardiomyocytes (CMs). STORM imaging shows M-band clustered regions of bound titin-mEos3.2 with few soluble titin-mEos3.2 molecules. FRAP revealed a baseline titin-mEos3.2 fluorescence recovery of 68% and half-life of ~1.2 h, suggesting a rapid exchange of sarcomeric titin with soluble titin. However, paraformaldehyde-fixed and permeabilized titin-mEos3.2 hiPSC-CMs surprisingly revealed a 55% fluorescence recovery. Whole cell FRAP analysis in paraformaldehyde-fixed, cycloheximide-treated, and untreated titin-mEos3.2 hiPSC-CMs displayed no significant differences in fluorescence recovery. FRAP in fixed HEK 293T expressing cytosolic mEos3.2 demonstrates a 58% fluorescence recovery. These data suggest that titin-mEos3.2 is subject to reversible photobleaching following FRAP. Using a mouse titin-eGFP model, we demonstrate that no reversible photobleaching occurs. Our results reveal that reversible photobleaching accounts for the majority of titin recovery in the titin-mEos3.2 hiPSC-CM model and should warrant as a caution in the extrapolation of reliable FRAP data from specific fluorescent proteins in long-term cell imaging.
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Affiliation(s)
- Adrian G Cadar
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, Tennessee
| | - Tromondae K Feaster
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Kevin R Bersell
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Lili Wang
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - TingTing Hong
- Smidt Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California
| | - Joseph A Balsamo
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Zhentao Zhang
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, Tennessee
| | - Young Wook Chun
- Department of Medicine, Division of Cardiovascular Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Young-Jae Nam
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, Tennessee
| | - Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Björn C Knollmann
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Dan M Roden
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Chee C Lim
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, Tennessee
| | - Charles C Hong
- Department of Medicine, Division of Cardiovascular Medicine, University of Maryland School of Medicine, Baltimore, Maryland
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Hoppins S, Lackner LL, Lee JE, Mears JA. In vitro and in vivo assays for mitochondrial fission and fusion. Methods Cell Biol 2019; 155:491-518. [PMID: 32183974 PMCID: PMC7863990 DOI: 10.1016/bs.mcb.2019.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mitochondria are required for cell survival and are best known for their role in energy production. These organelles also participate in many other biological processes that are critical for cellular function, and thus, play a central role in cellular life and death decisions. In a majority of cell types, mitochondria form highly dynamic, reticular networks. Maintaining the shape of these complex, ever-changing networks is critical for mitochondrial and cellular function, and requires the conserved activities of mitochondrial fission and fusion. Great advances in our knowledge about the molecular machines that mediate these dynamic activities have been made over the past 2 decades. These advances have been driven by the use of highly complementary in vitro and in vivo approaches that have proven extremely powerful for studying the complex membrane remodeling processes that drive fission and fusion of the organelle. In this chapter, we detail current methods used to examine the mechanisms and regulation of mitochondrial fission and fusion in vitro and in vivo.
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Affiliation(s)
- Suzanne Hoppins
- Department of Biochemistry, University of Washington School of Medicine, Seattle, WA, United States.
| | - Laura L Lackner
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States.
| | - Jason E Lee
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO, United States.
| | - Jason A Mears
- Department of Pharmacology, Center for Mitochondrial Diseases, and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, OH, United States.
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Espadas J, Pendin D, Bocanegra R, Escalada A, Misticoni G, Trevisan T, Velasco Del Olmo A, Montagna A, Bova S, Ibarra B, Kuzmin PI, Bashkirov PV, Shnyrova AV, Frolov VA, Daga A. Dynamic constriction and fission of endoplasmic reticulum membranes by reticulon. Nat Commun 2019; 10:5327. [PMID: 31757972 PMCID: PMC6876568 DOI: 10.1038/s41467-019-13327-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 10/25/2019] [Indexed: 12/16/2022] Open
Abstract
The endoplasmic reticulum (ER) is a continuous cell-wide membrane network. Network formation has been associated with proteins producing membrane curvature and fusion, such as reticulons and atlastin. Regulated network fragmentation, occurring in different physiological contexts, is less understood. Here we find that the ER has an embedded fragmentation mechanism based upon the ability of reticulon to produce fission of elongating network branches. In Drosophila, Rtnl1-facilitated fission is counterbalanced by atlastin-driven fusion, with the prevalence of Rtnl1 leading to ER fragmentation. Ectopic expression of Drosophila reticulon in COS-7 cells reveals individual fission events in dynamic ER tubules. Consistently, in vitro analyses show that reticulon produces velocity-dependent constriction of lipid nanotubes leading to stochastic fission via a hemifission mechanism. Fission occurs at elongation rates and pulling force ranges intrinsic to the ER, thus suggesting a principle whereby the dynamic balance between fusion and fission controlling organelle morphology depends on membrane motility.
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Affiliation(s)
- Javier Espadas
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular, Biology, University of the Basque Country, Leioa, 48940, Spain
| | - Diana Pendin
- Scientific Institute, IRCCS E. Medea, Laboratory of Molecular Biology, Bosisio Parini, Lecco, Italy
- Neuroscience Institute, Italian National Research Council (CNR), Padova, Italy
| | - Rebeca Bocanegra
- IMDEA Nanociencia, C/Faraday 9, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain
| | - Artur Escalada
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular, Biology, University of the Basque Country, Leioa, 48940, Spain
| | - Giulia Misticoni
- Scientific Institute, IRCCS E. Medea, Laboratory of Molecular Biology, Bosisio Parini, Lecco, Italy
| | - Tatiana Trevisan
- Scientific Institute, IRCCS E. Medea, Laboratory of Molecular Biology, Bosisio Parini, Lecco, Italy
| | - Ariana Velasco Del Olmo
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular, Biology, University of the Basque Country, Leioa, 48940, Spain
| | - Aldo Montagna
- Scientific Institute, IRCCS E. Medea, Laboratory of Molecular Biology, Bosisio Parini, Lecco, Italy
| | - Sergio Bova
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Borja Ibarra
- IMDEA Nanociencia, C/Faraday 9, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain
- Nanobiotecnología (IMDEA-Nanociencia) Unidad Asociada al Centro Nacional de Biotecnologia (CSIC), 28049, Madrid, Spain
| | - Peter I Kuzmin
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Pavel V Bashkirov
- Federal Research and Clinical Centre of Physical-Chemical Medicine, Moscow, 119435, Russia
| | - Anna V Shnyrova
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular, Biology, University of the Basque Country, Leioa, 48940, Spain
| | - Vadim A Frolov
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular, Biology, University of the Basque Country, Leioa, 48940, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain.
| | - Andrea Daga
- Scientific Institute, IRCCS E. Medea, Laboratory of Molecular Biology, Bosisio Parini, Lecco, Italy.
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Lee CA, Blackstone C. ER morphology and endo-lysosomal crosstalk: Functions and disease implications. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158544. [PMID: 31678515 DOI: 10.1016/j.bbalip.2019.158544] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/13/2019] [Accepted: 09/16/2019] [Indexed: 02/03/2023]
Abstract
The endoplasmic reticulum (ER) is a continuous endomembrane system comprising the nuclear envelope, ribosome-studded sheets, dense peripheral matrices, and an extensive polygonal network of interconnected tubules. In addition to performing numerous critical cellular functions, the ER makes extensive contacts with other organelles, including endosomes and lysosomes. The molecular and functional characterization of these contacts has advanced significantly over the past several years. These contacts participate in key functions such as cholesterol transfer, endosome tubule fission, and Ca2+ exchange. Disruption of key proteins at these sites can result in often severe diseases, particularly those affecting the nervous system.
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Affiliation(s)
- Crystal A Lee
- Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Craig Blackstone
- Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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Karagöz GE, Acosta-Alvear D, Walter P. The Unfolded Protein Response: Detecting and Responding to Fluctuations in the Protein-Folding Capacity of the Endoplasmic Reticulum. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a033886. [PMID: 30670466 DOI: 10.1101/cshperspect.a033886] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Most of the secreted and plasma membrane proteins are synthesized on membrane-bound ribosomes on the endoplasmic reticulum (ER). They require engagement of ER-resident chaperones and foldases that assist in their folding and maturation. Since protein homeostasis in the ER is crucial for cellular function, the protein-folding status in the organelle's lumen is continually surveyed by a network of signaling pathways, collectively called the unfolded protein response (UPR). Protein-folding imbalances, or "ER stress," are detected by highly conserved sensors that adjust the ER's protein-folding capacity according to the physiological needs of the cell. We review recent developments in the field that have provided new insights into the ER stress-sensing mechanisms used by UPR sensors and the mechanisms by which they integrate various cellular inputs to adjust the folding capacity of the organelle to accommodate to fluctuations in ER protein-folding demands.
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Affiliation(s)
- G Elif Karagöz
- Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94143
| | - Diego Acosta-Alvear
- Department of Molecular, Cellular, and Developmental Biology, University of California at Santa Barbara, Santa Barbara, California 93106
| | - Peter Walter
- Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94143
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Gao G, Zhu C, Liu E, Nabi IR. Reticulon and CLIMP-63 regulate nanodomain organization of peripheral ER tubules. PLoS Biol 2019; 17:e3000355. [PMID: 31469817 PMCID: PMC6742417 DOI: 10.1371/journal.pbio.3000355] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 09/12/2019] [Accepted: 07/26/2019] [Indexed: 11/18/2022] Open
Abstract
The endoplasmic reticulum (ER) is an expansive, membrane-enclosed organelle composed of smooth peripheral tubules and rough, ribosome-studded central ER sheets whose morphology is determined, in part, by the ER-shaping proteins, reticulon (RTN) and cytoskeleton-linking membrane protein 63 (CLIMP-63), respectively. Here, stimulated emission depletion (STED) super-resolution microscopy shows that reticulon4a (RTN4a) and CLIMP-63 also regulate the organization and dynamics of peripheral ER tubule nanodomains. STED imaging shows that lumenal ER monomeric oxidizing environment-optimized green fluorescent protein (ERmoxGFP), membrane Sec61βGFP, knock-in calreticulin-GFP, and antibody-labeled ER-resident proteins calnexin and derlin-1 are all localized to periodic puncta along the length of peripheral ER tubules that are not readily observable by diffraction limited confocal microscopy. RTN4a segregates away from and restricts lumenal blob length, while CLIMP-63 associates with and increases lumenal blob length. RTN4a and CLIMP-63 also regulate the nanodomain distribution of ER-resident proteins, being required for the preferential segregation of calnexin and derlin-1 puncta away from lumenal ERmoxGFP blobs. High-speed (40 ms/frame) live cell STED imaging shows that RTN4a and CLIMP-63 regulate dynamic nanoscale lumenal compartmentalization along peripheral ER tubules. RTN4a enhances and CLIMP-63 disrupts the local accumulation of lumenal ERmoxGFP at spatially defined sites along ER tubules. The ER-shaping proteins RTN and CLIMP-63 therefore regulate lumenal ER nanodomain heterogeneity, interaction with ER-resident proteins, and dynamics in peripheral ER tubules.
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Affiliation(s)
- Guang Gao
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Chengjia Zhu
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Emma Liu
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Ivan R. Nabi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
- * E-mail:
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43
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Pan S, Zhou J, Liu W, Ye Y, Chen G, Xu J, Qian Z, Chen J, Feng H. Viscosity-sensitive thiolated gold nanoclusters with diffusion-controlled emission for intracellular viscosity imaging. Analyst 2019; 144:4483-4487. [PMID: 31270525 DOI: 10.1039/c9an01035a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A unique diffusion-dependent emission phenomenon of gold nanoclusters was discovered, and can be regulated by the variation in viscosity and temperature. This specific property of gold nanoclusters was further used for viscosity monitoring in live cells, and the results demonstrated that gold nanoclusters are capable of real-time monitoring the abnormal viscosity change inside the cells.
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Affiliation(s)
- Saifei Pan
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
| | - Jin Zhou
- College of Pharmacy, Weifang Medical University, Weifang 261053, People's Republic of China
| | - Weidong Liu
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
| | - Yuxin Ye
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
| | - Guilin Chen
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
| | - Jing Xu
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
| | - Zhaosheng Qian
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
| | - Jianrong Chen
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
| | - Hui Feng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
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44
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Wang Y, Kory N, BasuRay S, Cohen JC, Hobbs HH. PNPLA3, CGI-58, and Inhibition of Hepatic Triglyceride Hydrolysis in Mice. Hepatology 2019; 69:2427-2441. [PMID: 30802989 PMCID: PMC6563103 DOI: 10.1002/hep.30583] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 02/16/2019] [Indexed: 12/12/2022]
Abstract
A variant (148M) in patatin-like phospholipase domain-containing protein 3 (PNPLA3) is a major risk factor for fatty liver disease. Despite its clinical importance, the pathogenic mechanism linking the variant to liver disease remains poorly defined. Previously, we showed that PNPLA3(148M) accumulates to high levels on hepatic lipid droplets (LDs). Here we examined the effect of that accumulation on triglyceride (TG) hydrolysis by adipose triglyceride lipase (ATGL), the major lipase in the liver. As expected, overexpression of ATGL in cultured hepatoma (HuH-7) cells depleted the cells of LDs, but unexpectedly, co-expression of PNPLA3(wild type [WT] or 148M) with ATGL inhibited that depletion. The inhibitory effect of PNPLA3 was not caused by the displacement of ATGL from LDs. We tested the hypothesis that PNPLA3 interferes with ATGL activity by interacting with its cofactor, comparative gene identification-58 (CGI-58). Evidence supporting such an interaction came from two findings. First, co-expression of PNPLA3 and CGI-58 resulted in LD depletion in cultured cells, but expression of PNPLA3 alone did not. Second, PNPLA3 failed to localize to hepatic LDs in liver-specific Cgi-58 knockout (KO) mice. Moreover, overexpression of PNPLA3(148M) increased hepatic TG levels in WT, but not in Cgi-58 KO mice. Thus, the pro-steatotic effects of PNPLA3 required the presence of CGI-58. Co-immunoprecipitation and pulldown experiments in livers of mice and in vitro using purified proteins provided evidence that PNPLA3 and CGI-58 can interact directly. Conclusion: Taken together, these findings are consistent with a model in which PNPLA3(148M) promotes steatosis by CGI-58-dependent inhibition of ATGL on LDs.
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Affiliation(s)
- Yang Wang
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Nora Kory
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Soumik BasuRay
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Jonathan C. Cohen
- Department of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTX,The Center for Human NutritionUniversity of Texas Southwestern Medical CenterDallas TX
| | - Helen H. Hobbs
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX,Department of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTX,Howard Hughes Medical InstituteUniversity of Texas Southwestern Medical CenterDallasTX
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Taylor CW, Machaca K. IP3 receptors and store-operated Ca2+ entry: a license to fill. Curr Opin Cell Biol 2019; 57:1-7. [DOI: 10.1016/j.ceb.2018.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/05/2018] [Indexed: 10/28/2022]
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46
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Single particle trajectories reveal active endoplasmic reticulum luminal flow. Nat Cell Biol 2018; 20:1118-1125. [PMID: 30224760 PMCID: PMC6435195 DOI: 10.1038/s41556-018-0192-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 08/09/2018] [Indexed: 01/22/2023]
Abstract
The Endoplasmic Reticulum (ER), a network of membranous sheets and pipes, supports functions encompassing biogenesis of secretory proteins and delivery of functional solutes throughout the cell1,2. Molecular mobility through the ER network enables these functionalities, but diffusion alone is not sufficient to explain luminal transport across supramicron distances. Understanding the ER structure-function relationship is critical in light of mutations in ER morphology regulating proteins that give rise to neurodegenerative disorders3,4. Here, super-resolution microscopy and analysis of single particle trajectories of ER luminal proteins revealed that the topological organization of the ER correlates with distinct trafficking modes of its luminal content: with a dominant diffusive component in tubular junctions and a fast flow component in tubules. Particle trajectory orientations resolved over time revealed an alternating current of the ER contents, whilst fast ER super-resolution identified energy-dependent tubule contraction events at specific points as a plausible mechanism for generating active ER luminal flow. The discovery of active flow in the ER has implications for timely ER content distribution throughout the cell, particularly important for cells with extensive ER-containing projections such as neurons.
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47
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Chen E, Esquerra RM, Meléndez PA, Chandrasekaran SS, Kliger DS. Microviscosity in E. coli Cells from Time-Resolved Linear Dichroism Measurements. J Phys Chem B 2018; 122:11381-11389. [PMID: 30118225 DOI: 10.1021/acs.jpcb.8b07362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A protein's folding or function depends on its mobility through the viscous environment that is defined by the presence of macromolecules throughout the cell. The relevant parameter for this mobility is microviscosity-the viscosity on a time and distance scale that is important for protein folding/function movements. A quasi-null, ultrasensitive time-resolved linear dichroism (TRLD) spectroscopy is proving to be a useful tool for measurements of viscosity on this scale, with previous in vitro studies reporting on the microviscosities of crowded environments mimicked by high concentrations of different macromolecules. This study reports the microviscosity experienced by myoglobin in the E. coli cell's heterogeneous cytoplasm by using TRLD to measure rotational diffusion times. The results show that photolyzed deoxyMb ensembles randomize through environment-dependent rotational diffusion with a lifetime of 34 ± 6 ns. This value corresponds to a microviscosity of 2.82 ± 0.42 cP, which is consistent with previous reports of cytoplasmic viscosity in E. coli. The results of these TRLD studies in E. coli (1) provide a measurement of myoglobin mobility in the cytoplasm, (2) taken together with in vitro TRLD studies yield new insights into the nature of the cytoplasmic environment in cells, and (3) demonstrate the feasibility of TRLD as a probe of intracellular viscosity.
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Affiliation(s)
- Eefei Chen
- Department of Chemistry and Biochemistry , University of California , Santa Cruz , California 95064 , United States
| | - Raymond M Esquerra
- Department of Chemistry and Biochemistry , San Francisco State University , San Francisco , California 94132 , United States
| | - Philipp A Meléndez
- Department of Chemistry and Biochemistry , San Francisco State University , San Francisco , California 94132 , United States
| | - Sita S Chandrasekaran
- Department of Chemistry and Biochemistry , San Francisco State University , San Francisco , California 94132 , United States
| | - David S Kliger
- Department of Chemistry and Biochemistry , University of California , Santa Cruz , California 95064 , United States
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48
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Lippincott-Schwartz J, Snapp EL, Phair RD. The Development and Enhancement of FRAP as a Key Tool for Investigating Protein Dynamics. Biophys J 2018; 115:1146-1155. [PMID: 30219286 DOI: 10.1016/j.bpj.2018.08.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/27/2018] [Accepted: 08/06/2018] [Indexed: 01/18/2023] Open
Abstract
The saga of fluorescence recovery after photobleaching (FRAP) illustrates how disparate technical developments impact science. Starting with the classic 1976 Axelrod et al. work in Biophysical Journal, FRAP (originally fluorescence photobleaching recovery) opened the door to extraction of quantitative information from photobleaching experiments, laying the experimental and theoretical groundwork for quantifying both the mobility and the mobile fraction of a labeled population of proteins. Over the ensuing years, FRAP's reach dramatically expanded, with new developments in GFP technology and turn-key confocal microscopy, which enabled measurement of protein diffusion and binding/dissociation rates in virtually every compartment within the cell. The FRAP technique and data catalyzed an exchange of ideas between biophysicists studying membrane dynamics, cell biologists focused on intracellular dynamics, and systems biologists modeling the dynamics of cell activity. The outcome transformed the field of cellular biology, leading to a fundamental rethinking of long-held theories of cellular dynamism. Here, we review the pivotal FRAP studies that made these developments and conceptual changes possible, which gave rise to current models of complex cell dynamics.
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Affiliation(s)
| | - Erik Lee Snapp
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia.
| | - Robert D Phair
- Integrative Bioinformatics, Inc., Mountain View, California
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49
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Wang J, Yin Y, Lau S, Sankaran J, Rothenberg E, Wohland T, Meier-Schellersheim M, Knaut H. Anosmin1 Shuttles Fgf to Facilitate Its Diffusion, Increase Its Local Concentration, and Induce Sensory Organs. Dev Cell 2018; 46:751-766.e12. [PMID: 30122631 DOI: 10.1016/j.devcel.2018.07.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 05/26/2018] [Accepted: 07/18/2018] [Indexed: 02/08/2023]
Abstract
Growth factors induce and pattern sensory organs, but how their distribution is regulated by the extracellular matrix (ECM) is largely unclear. To address this question, we analyzed the diffusion behavior of Fgf10 molecules during sensory organ formation in the zebrafish posterior lateral line primordium. In this tissue, secreted Fgf10 induces organ formation at a distance from its source. We find that most Fgf10 molecules are highly diffusive and move rapidly through the ECM. We identify Anosmin1, which when mutated in humans causes Kallmann Syndrome, as an ECM protein that binds to Fgf10 and facilitates its diffusivity by increasing the pool of fast-moving Fgf10 molecules. In the absence of Anosmin1, Fgf10 levels are reduced and organ formation is impaired. Global overexpression of Anosmin1 slows the fast-moving Fgf10 molecules and results in Fgf10 dispersal. These results suggest that Anosmin1 liberates ECM-bound Fgf10 and shuttles it to increase its signaling range.
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Affiliation(s)
- John Wang
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Yandong Yin
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Stephanie Lau
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Jagadish Sankaran
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Thorsten Wohland
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Martin Meier-Schellersheim
- Laboratory of Systems Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Holger Knaut
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA.
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Llancalahuen FM, Fuentes JA, Carreño A, Zúñiga C, Páez-Hernández D, Gacitúa M, Polanco R, Preite MD, Arratia-Pérez R, Otero C. New Properties of a Bioinspired Pyridine Benzimidazole Compound as a Novel Differential Staining Agent for Endoplasmic Reticulum and Golgi Apparatus in Fluorescence Live Cell Imaging. Front Chem 2018; 6:345. [PMID: 30211148 PMCID: PMC6123694 DOI: 10.3389/fchem.2018.00345] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 07/23/2018] [Indexed: 12/16/2022] Open
Abstract
In this study, we explored new properties of the bioinspired pyridine benzimidazole compound B2 (2,4-di-tert-butyl-6-(3H-imidazo[4,5-c]pyridine-2-yl)phenol) regarding its potential use as a differential biomarker. For that, we performed 1D 1HNMR (TOCSY), UV-Vis absorption spectra in different organic solvents, voltammetry profile (including a scan-rate study), and TD-DFT calculations that including NBO analyses, to provide valuable information about B2 structure and luminescence. In our study, we found that the B2 structure is highly stable, where the presence of an intramolecular hydrogen bond (IHB) seems to have a crucial role in the stability of luminescence, and its emission can be assigned as fluorescence. In fact, we found that the relatively large Stokes Shift observed for B2 (around 175 nm) may be attributed to the stability of the B2 geometry and the strength of its IHB. On the other hand, we determined that B2 is biocompatible by cytotoxicity experiments in HeLa cells, an epithelial cell line. Furthermore, in cellular assays we found that B2 could be internalized by passive diffusion in absence of artificial permeabilization at short incubation times (15 min to 30 min). Fluorescence microscopy studies confirmed that B2 accumulates in the endoplasmic reticulum (ER) and Golgi apparatus, two organelles involved in the secretory pathway. Finally, we determined that B2 exhibited no noticeable blinking or bleaching after 1 h of continuous exposure. Thus, B2 provides a biocompatible, rapid, simple, and efficient way to fluorescently label particular organelles, producing similar results to that obtained with other well-established but more complex methods.
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Affiliation(s)
- Felipe M Llancalahuen
- Escuela de Química y Farmacia, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Juan A Fuentes
- Laboratorio de Patogénesis y Genética Bacteriana, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Alexander Carreño
- Center of Applied Nanosciences, Universidad Andres Bello, Santiago, Chile.,Fondo Nacional de Ciencia y Tecnología (FONDECYT), Santiago, Chile
| | - César Zúñiga
- Center of Applied Nanosciences, Universidad Andres Bello, Santiago, Chile
| | | | | | - Rubén Polanco
- Centro de Biotecnología Vegeta, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Marcelo D Preite
- Departamento de Química Orgánica, Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Carolina Otero
- Escuela de Química y Farmacia, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
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