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Wang H, Qian T, Zhao Y, Zhuo Y, Wu C, Osakada T, Chen P, Chen Z, Ren H, Yan Y, Geng L, Fu S, Mei L, Li G, Wu L, Jiang Y, Qian W, Zhang L, Peng W, Xu M, Hu J, Jiang M, Chen L, Tang C, Zhu Y, Lin D, Zhou JN, Li Y. A tool kit of highly selective and sensitive genetically encoded neuropeptide sensors. Science 2023; 382:eabq8173. [PMID: 37972184 DOI: 10.1126/science.abq8173] [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: 05/03/2022] [Accepted: 10/02/2023] [Indexed: 11/19/2023]
Abstract
Neuropeptides are key signaling molecules in the endocrine and nervous systems that regulate many critical physiological processes. Understanding the functions of neuropeptides in vivo requires the ability to monitor their dynamics with high specificity, sensitivity, and spatiotemporal resolution. However, this has been hindered by the lack of direct, sensitive, and noninvasive tools. We developed a series of GRAB (G protein-coupled receptor activation‒based) sensors for detecting somatostatin (SST), corticotropin-releasing factor (CRF), cholecystokinin (CCK), neuropeptide Y (NPY), neurotensin (NTS), and vasoactive intestinal peptide (VIP). These fluorescent sensors, which enable detection of specific neuropeptide binding at nanomolar concentrations, establish a robust tool kit for studying the release, function, and regulation of neuropeptides under both physiological and pathophysiological conditions.
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Affiliation(s)
- Huan Wang
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Tongrui Qian
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Yulin Zhao
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Yizhou Zhuo
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Chunling Wu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Takuya Osakada
- Department of Psychiatry and Department of Neuroscience and Physiology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Peng Chen
- Institute of Brain Science, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, China
- Chinese Academy of Sciences Key Laboratory of Brain Function and Diseases, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Zijun Chen
- Shenzhen Key Laboratory of Drug Addiction, Shenzhen Neher Neural Plasticity Laboratory, Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Huixia Ren
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Yuqi Yan
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Lan Geng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Shengwei Fu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Long Mei
- Department of Psychiatry and Department of Neuroscience and Physiology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Guochuan Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Ling Wu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Yiwen Jiang
- Department of Psychiatry and Department of Neuroscience and Physiology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Weiran Qian
- Institute of Molecular Medicine, Peking University, Beijing 100871, China
| | - Li Zhang
- Department of Physiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Wanling Peng
- Chinese Academy of Sciences Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Min Xu
- Chinese Academy of Sciences Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ji Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Man Jiang
- Department of Physiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Liangyi Chen
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Chao Tang
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Yingjie Zhu
- Shenzhen Key Laboratory of Drug Addiction, Shenzhen Neher Neural Plasticity Laboratory, Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Dayu Lin
- Department of Psychiatry and Department of Neuroscience and Physiology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Jiang-Ning Zhou
- Institute of Brain Science, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, China
- Chinese Academy of Sciences Key Laboratory of Brain Function and Diseases, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- National Biomedical Imaging Center, Peking University, Beijing 100871, China
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2
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Yadav GP, Wang H, Ouwendijk J, Cross S, Wang Q, Qin F, Verkade P, Zhu MX, Jiang QX. Chromogranin B (CHGB) is dimorphic and responsible for dominant anion channels delivered to cell surface via regulated secretion. Front Mol Neurosci 2023; 16:1205516. [PMID: 37435575 PMCID: PMC10330821 DOI: 10.3389/fnmol.2023.1205516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/26/2023] [Indexed: 07/13/2023] Open
Abstract
Regulated secretion is conserved in all eukaryotes. In vertebrates granin family proteins function in all key steps of regulated secretion. Phase separation and amyloid-based storage of proteins and small molecules in secretory granules require ion homeostasis to maintain their steady states, and thus need ion conductances in granule membranes. But granular ion channels are still elusive. Here we show that granule exocytosis in neuroendocrine cells delivers to cell surface dominant anion channels, to which chromogranin B (CHGB) is critical. Biochemical fractionation shows that native CHGB distributes nearly equally in soluble and membrane-bound forms, and both reconstitute highly selective anion channels in membrane. Confocal imaging resolves granular membrane components including proton pumps and CHGB in puncta on the cell surface after stimulated exocytosis. High pressure freezing immuno-EM reveals a major fraction of CHGB at granule membranes in rat pancreatic β-cells. A cryo-EM structure of bCHGB dimer of a nominal 3.5 Å resolution delineates a central pore with end openings, physically sufficient for membrane-spanning and large single channel conductance. Together our data support that CHGB-containing (CHGB+) channels are characteristic of regulated secretion, and function in granule ion homeostasis near the plasma membrane or possibly in other intracellular processes.
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Affiliation(s)
- Gaya P. Yadav
- Departments of Microbiology and Cell Science and of Medicinal Chemistry, University of Florida, Gainesville, FL, United States
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
- Laboratory of Molecular Physiology and Biophysics, Hauptman-Woodward Medical Research Institute, Buffalo, NY, United States
| | - Haiyuan Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Joke Ouwendijk
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Stephen Cross
- Wolfson Bioimaging facility, University of Bristol, Bristol, United Kingdom
| | - Qiaochu Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Feng Qin
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Michael X. Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Qiu-Xing Jiang
- Departments of Microbiology and Cell Science and of Medicinal Chemistry, University of Florida, Gainesville, FL, United States
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
- Laboratory of Molecular Physiology and Biophysics, Hauptman-Woodward Medical Research Institute, Buffalo, NY, United States
- Cryo-EM Center, Laoshan Laboratory, Qingdao, Shandong, China
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3
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Recent Advances in Fluorescence Recovery after Photobleaching for Decoupling Transport and Kinetics of Biomacromolecules in Cellular Physiology. Polymers (Basel) 2022; 14:polym14091913. [PMID: 35567083 PMCID: PMC9105003 DOI: 10.3390/polym14091913] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [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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4
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Lopez Ruiz JR, Ernst SA, Holz RW, Stuenkel EL. Basal and Stress-Induced Network Activity in the Adrenal Medulla In Vivo. Front Endocrinol (Lausanne) 2022; 13:875865. [PMID: 35795145 PMCID: PMC9250985 DOI: 10.3389/fendo.2022.875865] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/12/2022] [Indexed: 11/23/2022] Open
Abstract
The adrenal medulla plays a critical role in mammalian homeostasis and the stress response. It is populated by clustered chromaffin cells that secrete epinephrine or norepinephrine along with peptides into the bloodstream affecting distant target organs. Despite been heavily studied, the central control of adrenal medulla and in-situ spatiotemporal responsiveness remains poorly understood. For this work, we continuously monitored the electrical activity of individual adrenomedullary chromaffin cells in the living anesthetized rat using multielectrode arrays. We measured the chromaffin cell activity under basal and physiological stress conditions and characterized the functional micro-architecture of the adrenal medulla. Under basal conditions, chromaffin cells fired action potentials with frequencies between ~0.2 and 4 Hz. Activity was almost completely driven by sympathetic inputs coming through the splanchnic nerve. Chromaffin cells were organized into independent local networks in which cells fired in a specific order, with latencies from hundreds of microseconds to a few milliseconds. Electrical stimulation of the splanchnic nerve evoked almost exactly the same spatiotemporal firing patterns that occurred spontaneously. Hypoglycemic stress, induced by insulin administration resulted in increased activity of a subset of the chromaffin cells. In contrast, respiratory arrest induced by lethal anesthesia resulted in an increase in the activity of virtually all chromaffin cells before cessation of all activity. These results suggest a stressor-specific activation of adrenomedullary chromaffin cell networks and revealed a surprisingly complex electrical organization that likely reflects the dynamic nature of the adrenal medulla's neuroendocrine output during basal conditions and during different types of physiological stress.
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Affiliation(s)
- Jose R Lopez Ruiz
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Stephen A Ernst
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Ronald W Holz
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Edward L Stuenkel
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, United States
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
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5
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Abbineni PS, Briguglio JS, Chapman ER, Holz RW, Axelrod D. VAMP2 and synaptotagmin mobility in chromaffin granule membranes: implications for regulated exocytosis. Mol Biol Cell 2021; 33:ar53. [PMID: 34851717 PMCID: PMC9265163 DOI: 10.1091/mbc.e21-10-0494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Granule-plasma membrane docking and fusion can only occur when proteins that enable these reactions are present at the granule-plasma membrane contact. Thus, the mobility of granule membrane proteins may influence docking, and membrane fusion. We measured the mobility of vesicle associated membrane protein 2 (VAMP2), synaptotagmin 1 (Syt1), and synaptotagmin 7 (Syt7) in chromaffin granule membranes in living chromaffin cells. We used a method that is not limited by standard optical resolution. A bright flash of strongly decaying evanescent field produced by total internal reflection (TIR) was used to photobleach GFP-labeled proteins in the granule membrane. Fluorescence recovery occurs as unbleached protein in the granule membrane distal from the glass interface diffuses into the more bleached proximal regions, enabling the measurement of diffusion coefficients. We found that VAMP2-EGFP and Syt7-EGFP are mobile with a diffusion coefficient of approximately 3 × 10-10 cm2/s. Syt1-EGFP mobility was below the detection limit. Utilizing these diffusion parameters, we estimated the time required for these proteins to arrive at docking and nascent fusion sites to be many tens of milliseconds. Our analyses raise the possibility that the diffusion characteristics of VAMP2 and Syt proteins could be a factor that influences the rate of exocytosis.
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Affiliation(s)
- Prabhodh S Abbineni
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan.,Department of Pharmacology, University of Michigan, Ann Arbor, Michigan
| | - Joseph S Briguglio
- Howard Hughes Medical Institute, Department of Neuroscience, University of Wisconsin, Madison, WI
| | - Edwin R Chapman
- Howard Hughes Medical Institute, Department of Neuroscience, University of Wisconsin, Madison, WI
| | - Ronald W Holz
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan
| | - Daniel Axelrod
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan.,Department of Physics, University of Michigan, Ann Arbor, Michigan
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6
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Parmer RJ, Gong Y, Yoo SH, Miles LA. Neuroendocrine Targeting of Tissue Plasminogen Activator (t-PA). JOURNAL OF NEUROLOGICAL DISORDERS & STROKE 2020; 7:1153. [PMID: 32549050 PMCID: PMC7297194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
t-PA has a widespread neuroendocrine distribution including prominent expression in chromaffin cells of the sympathoadrenal system. Chromaffin cell t-PA is sorted into catecholamine storage vesicles and co-released with catecholamines in response to sympathoadrenal activation, suggesting that catecholamine storage vesicles may serve as a reservoir for the rapid release of t-PA. Chromogranin A (CgA), a major core protein in secretory vesicles throughout the neuroendocrine system, may play a crucial role in targeting proteins into the regulated secretory pathway, by forming aggregated "granin" complexes to which other proteins destined for the regulated secretory vesicle bind and become separated from constitutively secreted proteins in the trans-Golgi network (TGN). Formation of such complexes is facilitated by conditions of the TGN (low pH, high Ca+2). We tested the hypothesis that t-PA interacts specifically with CgA and that this interaction is enhanced under conditions of the TGN. Immobilized t-PA was incubated with 125I-CgA. t-PA interacted specifically and saturably with CgA and the interaction was domain-specific, mediated by the EGF/finger and kringle 1 domains of t-PA and by a specific internal hydrophilic domain within CgA (KERTHQQKKHSSYEDELSEVL) as assessed by antibody and peptide competition studies. The interaction of t-PA with aggregated CgA complexes may play a role in the targeting of t-PA and its release from neurosecretory cells. These results may have broad implications for the regulation of local neurosecretory cell plasminogen activation under both normal physiological conditions and pathological conditions including cerebral ischemia.
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Affiliation(s)
- Robert J. Parmer
- Department of Medicine, University of California, USA
- Veterans Administration San Diego Healthcare System, San Diego, CA, USA
| | - Yun Gong
- Department of Pathology, M.D. Anderson Cancer Center, USA
| | | | - Lindsey A. Miles
- Department of Molecular Medicine, The Scripps Research Institute, USA
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7
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Sharma S, Lindau M. The fusion pore, 60 years after the first cartoon. FEBS Lett 2018; 592:3542-3562. [PMID: 29904915 DOI: 10.1002/1873-3468.13160] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 06/07/2018] [Accepted: 06/12/2018] [Indexed: 11/10/2022]
Abstract
Neurotransmitter release occurs in the form of quantal events by fusion of secretory vesicles with the plasma membrane, and begins with the formation of a fusion pore that has a conductance similar to that of a large ion channel or gap junction. In this review, we propose mechanisms of fusion pore formation and discuss their implications for fusion pore structure and function. Accumulating evidence indicates a direct role of soluble N-ethylmaleimide-sensitive-factor attachment receptor proteins in the opening of fusion pores. Fusion pores are likely neither protein channels nor purely lipid, but are of proteolipidic composition. Future perspectives to gain better insight into the molecular structure of fusion pores are discussed.
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Affiliation(s)
- Satyan Sharma
- Laboratory for Nanoscale Cell Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Manfred Lindau
- Laboratory for Nanoscale Cell Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.,School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
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8
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Bohannon KP, Bittner MA, Lawrence DA, Axelrod D, Holz RW. Slow fusion pore expansion creates a unique reaction chamber for co-packaged cargo. J Gen Physiol 2017; 149:921-934. [PMID: 28882880 PMCID: PMC5694939 DOI: 10.1085/jgp.201711842] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 08/21/2017] [Indexed: 12/29/2022] Open
Abstract
A lumenal secretory granule protein can slow fusion pore dilation and thus its own discharge. Bohannon et al. demonstrate another outcome: the creation of a nanoscale chemical reaction chamber for granule contents in which the pH is suddenly neutralized upon fusion. A lumenal secretory granule protein, tissue plasminogen activator (tPA), greatly slows fusion pore dilation and thereby slows its own discharge. We investigated another outcome of the long-lived narrow fusion pore: the creation of a nanoscale chemical reaction chamber for granule contents in which the pH is suddenly neutralized upon fusion. Bovine adrenal chromaffin cells endogenously express both tPA and its primary protein inhibitor, plasminogen activator inhibitor 1 (PAI). We found by immunocytochemistry that tPA and PAI are co-packaged in the same secretory granule. It is known that PAI irreversibly and covalently inactivates tPA at neutral pH. We demonstrate with zymography that the acidic granule lumen protects tPA from inactivation by PAI. Immunocytochemistry, total internal reflection fluorescence (TIRF) microscopy, and polarized TIRF microscopy demonstrated that co-packaged PAI and tPA remain together in granules for many seconds in the nanoscale reaction chamber, more than enough time to inhibit tPA and create a new secreted protein species.
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Affiliation(s)
- Kevin P Bohannon
- Department of Pharmacology, University of Michigan, Ann Arbor, MI
| | - Mary A Bittner
- Department of Pharmacology, University of Michigan, Ann Arbor, MI
| | - Daniel A Lawrence
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI.,Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
| | - Daniel Axelrod
- Department of Pharmacology, University of Michigan, Ann Arbor, MI.,Department of Physics, University of Michigan, Ann Arbor, MI.,LSA Biophysics, University of Michigan, Ann Arbor, MI
| | - Ronald W Holz
- Department of Pharmacology, University of Michigan, Ann Arbor, MI
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9
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Amyotrophic lateral sclerosis-linked mutations increase the viscosity of liquid-like TDP-43 RNP granules in neurons. Proc Natl Acad Sci U S A 2017; 114:E2466-E2475. [PMID: 28265061 DOI: 10.1073/pnas.1614462114] [Citation(s) in RCA: 161] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Ribonucleoprotein (RNP) granules are enriched in specific RNAs and RNA-binding proteins (RBPs) and mediate critical cellular processes. Purified RBPs form liquid droplets in vitro through liquid-liquid phase separation and liquid-like non-membrane-bound structures in cells. Mutations in the human RBPs TAR-DNA binding protein 43 (TDP-43) and RNA-binding protein FUS cause amyotrophic lateral sclerosis (ALS), but the biophysical properties of these proteins have not yet been studied in neurons. Here, we show that TDP-43 RNP granules in axons of rodent primary cortical neurons display liquid-like properties, including fusion with rapid relaxation to circular shape, shear stress-induced deformation, and rapid fluorescence recovery after photobleaching. RNP granules formed from wild-type TDP-43 show distinct biophysical properties depending on axonal location, suggesting maturation to a more stabilized structure is dependent on subcellular context, including local density and aging. Superresolution microscopy demonstrates that the stabilized population of TDP-43 RNP granules in the proximal axon is less circular and shows spiculated edges, whereas more distal granules are both more spherical and more dynamic. RNP granules formed by ALS-linked mutant TDP-43 are more viscous and exhibit disrupted transport dynamics. We propose these altered properties may confer toxic gain of function and reflect differential propensity for pathological transformation.
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10
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Finkenstaedt-Quinn SA, Qiu TA, Shin K, Haynes CL. Super-resolution imaging for monitoring cytoskeleton dynamics. Analyst 2016; 141:5674-5688. [PMID: 27549146 DOI: 10.1039/c6an00731g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cytoskeleton is a key cellular structure that is important in the control of cellular movement, structure, and sensing. To successfully image the individual cytoskeleton components, high resolution and super-resolution fluorescence imaging methods are needed. This review covers the three basic cytoskeletal elements and the relative benefits and drawbacks of fixed versus live cell imaging before moving on to recent studies using high resolution and super-resolution techniques. The techniques covered include the near-diffraction limited imaging methods of confocal microscopy and TIRF microscopy and the super-resolution fluorescence imaging methods of STORM, PALM, and STED.
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11
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Suzuki Y, Sano H, Tomczyk M, Brzoska T, Urano T. Activities of wild-type and variant tissue-type plasminogen activators retained on vascular endothelial cells. FEBS Open Bio 2016; 6:469-76. [PMID: 27419052 PMCID: PMC4856425 DOI: 10.1002/2211-5463.12057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 03/06/2016] [Accepted: 03/07/2016] [Indexed: 11/26/2022] Open
Abstract
We reported that tissue‐type plasminogen activator (tPA) secreted from vascular endothelial cells (VECs) is retained on the cell surface and effectively evokes both plasminogen activation and fibrin clot dissolution (fibrinolysis) on VECs. Here, to evaluate possibly different behaviors of variants of tPA, we quantitatively assessed these two events separately using green fluorescent protein (GFP)‐conjugated tPA in cultured human VECs. The amount of secreted wild‐type tPA‐GFP correlated well with both the activities of plasminogen activation (r = 0.66) and fibrinolysis (r = −0.93). A variant of tPA‐GFP, with a lower affinity to the surface of VECs but higher affinity to fibrin, showed higher fibrinolysis and lower plasminogen activation activity compared to the wild‐type.
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Affiliation(s)
- Yuko Suzuki
- Department of Medical Physiology Hamamatsu University School of Medicine Japan
| | - Hideto Sano
- Department of Medical Physiology Hamamatsu University School of Medicine Japan
| | - Martyna Tomczyk
- Department of Medical Physiology Hamamatsu University School of Medicine Japan
| | - Tomasz Brzoska
- Department of Medical Physiology Hamamatsu University School of Medicine Japan
| | - Tetsumei Urano
- Department of Medical Physiology Hamamatsu University School of Medicine Japan
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12
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Zimmerberg J, Blank PS. It's what's inside that matters. Biophys J 2014; 107:5-7. [PMID: 24988334 DOI: 10.1016/j.bpj.2014.05.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 05/06/2014] [Indexed: 10/25/2022] Open
Affiliation(s)
- Joshua Zimmerberg
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland.
| | - Paul S Blank
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
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