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Vicario N, Turnaturi R, Spitale FM, Torrisi F, Zappalà A, Gulino R, Pasquinucci L, Chiechio S, Parenti C, Parenti R. Intercellular communication and ion channels in neuropathic pain chronicization. Inflamm Res 2020; 69:841-850. [PMID: 32533221 DOI: 10.1007/s00011-020-01363-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/13/2020] [Accepted: 05/17/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Neuropathic pain is caused by primary lesion or dysfunction of either peripheral or central nervous system. Due to its complex pathogenesis, often related to a number of comorbidities, such as cancer, neurodegenerative and neurovascular diseases, neuropathic pain still represents an unmet clinical need, lacking long-term effective treatment and complex case-by-case approach. AIM AND METHODS We analyzed the recent literature on the role of selective voltage-sensitive sodium, calcium and potassium permeable channels and non-selective gap junctions (GJs) and hemichannels (HCs) in establishing and maintaining chronic neuropathic conditions. We finally focussed our review on the role of extracellular microenvironment modifications induced by resident glial cells and on the recent advances in cell-to-cell and cell-to-extracellular environment communication in chronic neuropathies. CONCLUSION In this review, we provide an update on the current knowledge of neuropathy chronicization processes with a focus on both neuronal and glial ion channels, as well as on channel-mediated intercellular communication.
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Affiliation(s)
- Nunzio Vicario
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rita Turnaturi
- Section of Medicinal Chemistry, Department of Drug Sciences, University of Catania, Catania, Italy
| | - Federica Maria Spitale
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Filippo Torrisi
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Agata Zappalà
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rosario Gulino
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Lorella Pasquinucci
- Section of Medicinal Chemistry, Department of Drug Sciences, University of Catania, Catania, Italy
| | - Santina Chiechio
- Section of Pharmacology, Department of Drug Sciences, University of Catania, Catania, Italy
- Oasi Research Institute IRCCS, Troina, Italy
| | - Carmela Parenti
- Section of Pharmacology, Department of Drug Sciences, University of Catania, Catania, Italy.
| | - Rosalba Parenti
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy.
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52
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Wang H, Peng X, Ge Y, Zhang S, Wang Z, Fan Y, Huang W, Qiu M, Ye RD. A Ganoderma-Derived Compound Exerts Inhibitory Effect Through Formyl Peptide Receptor 2. Front Pharmacol 2020; 11:337. [PMID: 32265709 PMCID: PMC7105723 DOI: 10.3389/fphar.2020.00337] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 03/06/2020] [Indexed: 12/28/2022] Open
Abstract
Formyl peptide receptors (FPRs) are G protein-coupled receptors (GPCRs) widely expressed in neutrophils and other phagocytes. FPRs play important roles in host defense, inflammation, and the pathogenesis of infectious and inflammatory diseases. Because of these functions, FPRs are potential targets for anti-inflammatory therapies. In order to search for potentially novel anti-inflammatory agents, we examined Ganoderma (Lingzhi), a Chinese medicinal herbs known for its anti-inflammatory effects, and found that compound 18 (C18) derived from Ganoderma cochlear could limit the inflammatory response through FPR-related signaling pathways. Further studies showed that C18 could bind to FPR2 and induce conformation change of the receptor that differed from the conformational change induced by the pan-agonist, WKYMVm. C18 inhibited at the receptor level and blocked WKYMVm signaling through FPR2, resulting in reduced superoxide production and compromised cell chemotaxis. These results identified for the first time that a Ganoderma-derived component with inhibitory effects that acts through a G protein-coupled receptor FPR2. Considering its less than optimal IC50 value, further optimization of C18 would be necessary for future applications.
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Affiliation(s)
- Huirong Wang
- Institute of Chinese Medical Sciences, State Key Laboratory of Quality Research in Chinese Medicine, University of Macau, Macau, Macau.,Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Xingrong Peng
- Kunming Institute of Botany, Chinese Academy of Science, Kunming, China
| | - Yunjun Ge
- Institute of Chinese Medical Sciences, State Key Laboratory of Quality Research in Chinese Medicine, University of Macau, Macau, Macau
| | - Shuo Zhang
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Zhenyi Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, China
| | - Yu Fan
- Institute of Chinese Medical Sciences, State Key Laboratory of Quality Research in Chinese Medicine, University of Macau, Macau, Macau
| | - Wei Huang
- Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Minghua Qiu
- Kunming Institute of Botany, Chinese Academy of Science, Kunming, China
| | - Richard D Ye
- Institute of Chinese Medical Sciences, State Key Laboratory of Quality Research in Chinese Medicine, University of Macau, Macau, Macau.,Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, China
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Totland MZ, Rasmussen NL, Knudsen LM, Leithe E. Regulation of gap junction intercellular communication by connexin ubiquitination: physiological and pathophysiological implications. Cell Mol Life Sci 2020; 77:573-591. [PMID: 31501970 PMCID: PMC7040059 DOI: 10.1007/s00018-019-03285-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 08/10/2019] [Accepted: 08/16/2019] [Indexed: 12/15/2022]
Abstract
Gap junctions consist of arrays of intercellular channels that enable adjacent cells to communicate both electrically and metabolically. Gap junctions have a wide diversity of physiological functions, playing critical roles in both excitable and non-excitable tissues. Gap junction channels are formed by integral membrane proteins called connexins. Inherited or acquired alterations in connexins are associated with numerous diseases, including heart failure, neuropathologies, deafness, skin disorders, cataracts and cancer. Gap junctions are highly dynamic structures and by modulating the turnover rate of connexins, cells can rapidly alter the number of gap junction channels at the plasma membrane in response to extracellular or intracellular cues. Increasing evidence suggests that ubiquitination has important roles in the regulation of endoplasmic reticulum-associated degradation of connexins as well as in the modulation of gap junction endocytosis and post-endocytic sorting of connexins to lysosomes. In recent years, researchers have also started to provide insights into the physiological roles of connexin ubiquitination in specific tissue types. This review provides an overview of the advances made in understanding the roles of connexin ubiquitination in the regulation of gap junction intercellular communication and discusses the emerging physiological and pathophysiological implications of these processes.
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Affiliation(s)
- Max Zachrisson Totland
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Nikoline Lander Rasmussen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
- Department of Medical Biology, University of Tromsø, Tromsø, Norway
| | - Lars Mørland Knudsen
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway
| | - Edward Leithe
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital, 0424, Oslo, Norway.
- K.G. Jebsen Colorectal Cancer Research Centre, Oslo University Hospital, Oslo, Norway.
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54
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Singh AK, Cancelas JA. Gap Junctions in the Bone Marrow Lympho-Hematopoietic Stem Cell Niche, Leukemia Progression, and Chemoresistance. Int J Mol Sci 2020; 21:E796. [PMID: 31991829 PMCID: PMC7038046 DOI: 10.3390/ijms21030796] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/19/2020] [Accepted: 01/23/2020] [Indexed: 12/15/2022] Open
Abstract
Abstract: The crosstalk between hematopoietic stem cells (HSC) and bone marrow (BM) microenvironment is critical for homeostasis and hematopoietic regeneration in response to blood formation emergencies after injury, and has been associated with leukemia transformation and progression. Intercellular signals by the BM stromal cells in the form of cell-bound or secreted factors, or by physical interaction, regulate HSC localization, maintenance, and differentiation within increasingly defined BM HSC niches. Gap junctions (GJ) are comprised of arrays of membrane embedded channels formed by connexin proteins, and control crucial signaling functions, including the transfer of ions, small metabolites, and organelles to adjacent cells which affect intracellular mechanisms of signaling and autophagy. This review will discuss the role of GJ in both normal and leukemic hematopoiesis, and highlight some of the most novel approaches that may improve the efficacy of cytotoxic drugs. Connexin GJ channels exert both cell-intrinsic and cell-extrinsic effects on HSC and BM stromal cells, involved in regenerative hematopoiesis after myelosuppression, and represent an alternative system of cell communication through a combination of electrical and metabolic coupling as well as organelle transfer in the HSC niche. GJ intercellular communication (GJIC) in the HSC niche improves cellular bioenergetics, and rejuvenates damaged recipient cells. Unfortunately, they can also support leukemia proliferation and survival by creating leukemic niches that provide GJIC dependent energy sources and facilitate chemoresistance and relapse. The emergence of new strategies to disrupt self-reinforcing malignant niches and intercellular organelle exchange in leukemic niches, while at the same time conserving normal hematopoietic GJIC function, could synergize the effect of chemotherapy drugs in eradicating minimal residual disease. An improved understanding of the molecular basis of connexin regulation in normal and leukemic hematopoiesis is warranted for the re-establishment of normal hematopoiesis after chemotherapy.
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Affiliation(s)
- Abhishek K. Singh
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229, USA;
- Hoxworth Blood Center, University of Cincinnati Academic Health Center, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Jose A. Cancelas
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229, USA;
- Hoxworth Blood Center, University of Cincinnati Academic Health Center, 3333 Burnet Ave., Cincinnati, OH 45229, USA
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55
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Petazzi RA, Aji AK, Chiantia S. Fluorescence microscopy methods for the study of protein oligomerization. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 169:1-41. [DOI: 10.1016/bs.pmbts.2019.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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56
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Doh JK, Enns CA, Beatty KE. Implementing VIPER for Imaging Cellular Proteins by Fluorescence Microscopy. Bio Protoc 2019; 9:e3413. [PMID: 32665966 PMCID: PMC7360171 DOI: 10.21769/bioprotoc.3413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 09/24/2019] [Accepted: 09/30/2019] [Indexed: 12/13/2022] Open
Abstract
Genetically-encoded tags are useful tools for multicolor and multi-scale cellular imaging. Versatile Interacting Peptide (VIP) tags, such as VIPER, are new genetically-encoded tags that can be used in various imaging applications. VIP tags consist of a coiled-coil heterodimer, with one peptide serving as the genetic tag and the other ("probe peptide") delivering a reporter compatible with imaging. Heterodimer formation is rapid and specific, allowing proteins to be selectively labeled for live-cell and fixed-cell imaging. In this Bio-Protocol, we include a detailed guide for implementing the VIPER technology for imaging receptors on live cells and intracellular targets in fixed cells. This protocol is complemented by two other Bio-Protocols outlining the use of VIPER (Doh et al., 2019a and 2019b).
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Affiliation(s)
- Julia K. Doh
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Caroline A. Enns
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Kimberly E. Beatty
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon 97239, USA
- OHSU Center for Spatial Systems Biomedicine, Oregon Health & Science University, Portland, Oregon 97239, USA
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57
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Doh JK, Chang YH, Enns CA, Lόpez CS, Beatty KE. Imaging VIPER-labeled Cellular Proteins by Correlative Light and Electron Microscopy. Bio Protoc 2019; 9:e3414. [PMID: 33654913 PMCID: PMC7853974 DOI: 10.21769/bioprotoc.3414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 09/24/2019] [Accepted: 09/30/2019] [Indexed: 01/02/2023] Open
Abstract
Advances in fluorescence microscopy (FM), electron microscopy (EM), and correlative light and EM (CLEM) offer unprecedented opportunities for studying diverse proteins and nanostructures involved in fundamental cell biology. It is now possible to visualize and quantify the spatial organization of cellular proteins and other macromolecules by FM, EM, and CLEM. However, tagging and tracking cellular proteins across size scales is restricted by the scarcity of methods for attaching appropriate reporter chemistries to target proteins. Namely, there are few genetic tags compatible with EM. To overcome these issues we developed Versatile Interacting Peptide (VIP) tags, genetically-encoded peptide tags that can be used to image proteins by fluorescence and EM. VIPER, a VIP tag, can be used to label cellular proteins with bright, photo-stable fluorophores for FM or electron-dense nanoparticles for EM. In this Bio-Protocol, we provide an instructional guide for implementing VIPER for imaging a cell-surface receptor by CLEM. This protocol is complemented by two other Bio-Protocols outlining the use of VIPER ( Doh et al., 2019a and 2019b).
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Affiliation(s)
- Julia K. Doh
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Young Hwan Chang
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon 97239, USA
- OHSU Center for Spatial Systems Biomedicine, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Caroline A. Enns
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Claudia S. Lόpez
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon 97239, USA
- OHSU Center for Spatial Systems Biomedicine, Oregon Health & Science University, Portland, Oregon 97239, USA
- Multiscale Microscopy Core, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Kimberly E. Beatty
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon 97239, USA
- OHSU Center for Spatial Systems Biomedicine, Oregon Health & Science University, Portland, Oregon 97239, USA
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58
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Otegui MS, Pennington JG. Electron tomography in plant cell biology. Microscopy (Oxf) 2019; 68:69-79. [PMID: 30452668 DOI: 10.1093/jmicro/dfy133] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/15/2018] [Accepted: 10/31/2018] [Indexed: 12/11/2022] Open
Abstract
Electron tomography (ET) approaches are based on the imaging of a biological specimen at different tilt angles by transmission electron microscopy (TEM). ET can be applied to both plastic-embedded and frozen samples. Technological advancements in TEM, direct electron detection, automated image collection, and imaging processing algorithms allow for 2-7-nm scale axial resolution in tomographic reconstructions of cells and organelles. In this review, we discussed the application of ET in plant cell biology and new opportunities for imaging plant cells by cryo-ET and other 3D electron microscopy approaches.
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Affiliation(s)
- Marisa S Otegui
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison WI, USA.,Laboratory of Molecular and Cellular Biology, University of Wisconsin-Madison, 1525 Linden Drive, Madison WI, USA.,Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison WI, USA
| | - Jannice G Pennington
- Institute for Molecular Virology, University of Wisconsin-Madison, 1525 Linden Drive, Madison WI, USA.,Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, USA
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59
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Schipper-Krom S, Sanz AS, van Bodegraven EJ, Speijer D, Florea BI, Ovaa H, Reits EA. Visualizing Proteasome Activity and Intracellular Localization Using Fluorescent Proteins and Activity-Based Probes. Front Mol Biosci 2019; 6:56. [PMID: 31482094 PMCID: PMC6710370 DOI: 10.3389/fmolb.2019.00056] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 07/02/2019] [Indexed: 12/18/2022] Open
Abstract
The proteasome is a multi-catalytic molecular machine that plays a key role in the degradation of many cytoplasmic and nuclear proteins. The proteasome is essential and proteasome malfunction is associated with various disease pathologies. Proteasome activity depends on its catalytic subunits which are interchangeable and also on the interaction with the associated regulatory cap complexes. Here, we describe and compare various methods that allow the study of proteasome function in living cells. Methods include the use of fluorescently tagged proteasome subunits and the use of activity-based proteasome probes. These probes can be used in both biochemical assays and in microscopy-based experiments. Together with tagged proteasomes, they can be used to study proteasome localization, dynamics, and activity.
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Affiliation(s)
- Sabine Schipper-Krom
- Department of Medical Biology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Alicia Sanz Sanz
- Department of Medical Biology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Emma J. van Bodegraven
- Department of Medical Biology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Dave Speijer
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Bogdan I. Florea
- Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands
| | - Huib Ovaa
- Department of Cell and Chemical Biology, Leiden University Medical Center, Oncode Institute, Leiden, Netherlands
| | - Eric A. Reits
- Department of Medical Biology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
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60
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Chia HE, Marsh ENG, Biteen JS. Extending fluorescence microscopy into anaerobic environments. Curr Opin Chem Biol 2019; 51:98-104. [DOI: 10.1016/j.cbpa.2019.05.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 04/22/2019] [Accepted: 05/13/2019] [Indexed: 12/01/2022]
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Self-Labeling Enzyme Tags for Analyses of Translocation of Type III Secretion System Effector Proteins. mBio 2019; 10:mBio.00769-19. [PMID: 31239375 PMCID: PMC6593401 DOI: 10.1128/mbio.00769-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type III secretion systems (T3SS) are molecular machines in Gram-negative pathogens that translocate effector proteins with central roles in virulence. The analyses of the translocation, subcellular localization, and mode of action of T3SS effector proteins are of central importance for the understanding of host-pathogen interaction and pathogenesis of bacterial infections. The analysis of translocation requires dedicated techniques to address the temporal and spatial dynamics of translocation. Here we describe a novel approach to deploy self-labeling enzymes (SLE) as universal tags for localization and tracking of translocated effector proteins. Effector-SLE fusion proteins allow live-cell imaging of translocation by T3SS, superresolution microscopy, and single-molecule tracking of effector motility in living host cells. We describe the application of the approach to T3SS effector proteins for invasion and intracellular lifestyle of Salmonella enterica serovar Typhimurium and to a T3SS effector of Yersinia enterocolitica The novel approach enables analyses of the role of T3SS in host-pathogen interaction at the highest temporal and spatial resolution, toward understanding the molecular mechanisms of their effector proteins.IMPORTANCE Type III secretion systems mediate translocation of effector proteins into mammalian cells. These proteins interfere with host cell functions, being main virulence factors of Gram-negative pathogens. Analyses of the process of translocation, the subcellular distribution, and the dynamics of effector proteins in host cells have been hampered by the lack of suitable tags and detection systems. Here we describe the use of self-labeling enzyme tags for generation of fusions with effector proteins that are translocated and functional in host cell manipulation. Self-labeling reactions with cell-permeable ligand dyes are possible prior to or after translocation. We applied the new approach to superresolution microscopy for effector protein translocation. For the first time, we show the dynamic properties of effector proteins in living host cells after translocation by intracellular bacteria. The new approach of self-labeling enzyme tags fusions will enable analyses of type III secretion system effector proteins with new dimensions of temporal and spatial resolution.
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Spectral tracing of deuterium for imaging glucose metabolism. Nat Biomed Eng 2019; 3:402-413. [PMID: 31036888 PMCID: PMC6599680 DOI: 10.1038/s41551-019-0393-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 03/17/2019] [Indexed: 01/31/2023]
Abstract
Cells and tissues often display pronounced spatial and dynamical metabolic heterogeneity. Prevalent glucose-imaging techniques report glucose uptake or catabolism activity, yet do not trace the functional utilization of glucose-derived anabolic products. Here, we report a microscopy technique for the optical imaging, via the spectral tracing of deuterium (referred to as STRIDE), of diverse macromolecules derived from glucose. Based on stimulated-Raman-scattering imaging, STRIDE visualizes the metabolic dynamics of newly synthesized macromolecules, such as DNA, protein, lipids and glycogen, via the enrichment and distinct spectra of carbon–deuterium bonds transferred from the deuterated glucose precursor. STRIDE can also use spectral differences derived from different glucose isotopologues to visualize temporally separated glucose populations in a pulse–chase manner. We also show that STRIDE can be used to image glucose metabolism in many mouse tissues, including tumours, the brain, the intestine and the liver, at a detection limit of 10 mM of carbon–deuterium bonds. STRIDE provides a high-resolution and chemically informative assessment of glucose anabolic utilization.
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63
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Oluwadare O, Highsmith M, Cheng J. An Overview of Methods for Reconstructing 3-D Chromosome and Genome Structures from Hi-C Data. Biol Proced Online 2019; 21:7. [PMID: 31049033 PMCID: PMC6482566 DOI: 10.1186/s12575-019-0094-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/01/2019] [Indexed: 01/08/2023] Open
Abstract
Over the past decade, methods for predicting three-dimensional (3-D) chromosome and genome structures have proliferated. This has been primarily due to the development of high-throughput, next-generation chromosome conformation capture (3C) technologies, which have provided next-generation sequencing data about chromosome conformations in order to map the 3-D genome structure. The introduction of the Hi-C technique-a variant of the 3C method-has allowed researchers to extract the interaction frequency (IF) for all loci of a genome at high-throughput and at a genome-wide scale. In this review we describe, categorize, and compare the various methods developed to map chromosome and genome structures from 3C data-particularly Hi-C data. We summarize the improvements introduced by these methods, describe the approach used for method evaluation, and discuss how these advancements shape the future of genome structure construction.
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Affiliation(s)
- Oluwatosin Oluwadare
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211 USA
| | - Max Highsmith
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211 USA
| | - Jianlin Cheng
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211 USA
- Informatics Institute, University of Missouri, Columbia, MO 65211 USA
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Xiong Y, Tian X, Ai HW. Molecular Tools to Generate Reactive Oxygen Species in Biological Systems. Bioconjug Chem 2019; 30:1297-1303. [PMID: 30986044 DOI: 10.1021/acs.bioconjchem.9b00191] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Reactive oxygen species (ROS) not only are byproducts of aerobic respiration, but also play vital roles in metabolism regulation and signal transductions. It is important to understand the functions of ROS in biological systems. In addition, scientists have made use of ROS to kill bacteria and tumors through a process known as photodynamic therapy (PDT). This paper provides a concise review of current molecular tools that can generate ROS in biological systems via either nongenetic or genetically encoded way. Challenges and perspectives are further discussed with the hope of broadening the applications of ROS generators in research and clinical settings.
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Affiliation(s)
- Ying Xiong
- Center for Membrane and Cell Physiology, Department of Molecular Physiology and Biological Physics, Department of Chemistry, and the UVA Cancer Center , University of Virginia , 1340 Jefferson Park Avenue , Charlottesville , Virginia 22908 , United States
| | - Xiaodong Tian
- Center for Membrane and Cell Physiology, Department of Molecular Physiology and Biological Physics, Department of Chemistry, and the UVA Cancer Center , University of Virginia , 1340 Jefferson Park Avenue , Charlottesville , Virginia 22908 , United States
| | - Hui-Wang Ai
- Center for Membrane and Cell Physiology, Department of Molecular Physiology and Biological Physics, Department of Chemistry, and the UVA Cancer Center , University of Virginia , 1340 Jefferson Park Avenue , Charlottesville , Virginia 22908 , United States
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Van Itallie CM, Lidman KF, Tietgens AJ, Anderson JM. Newly synthesized claudins but not occludin are added to the basal side of the tight junction. Mol Biol Cell 2019; 30:1406-1424. [PMID: 30943107 PMCID: PMC6724697 DOI: 10.1091/mbc.e19-01-0008] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A network of claudin strands creates continuous cell–cell contacts to form the intercellular tight junction barrier; a second protein, occludin, is associated along these strands. The physiological barrier remains stable despite protein turnover, which involves removal and replacement of claudins both in the steady state and during junction remodeling. Here we use a pulse–block–pulse labeling protocol with fluorescent ligands to label SNAP/CLIP-tags fused to claudins and occludin to identify their spatial trafficking pathways and kinetics in Madin–Darby canine kidney monolayers. We find that claudins are first delivered to the lateral membrane and, over time, enter the junction strand network from the basal side; this is followed by slow replacement of older claudins in the strands. In contrast, even at early times, newly synthesized occludin is found throughout the network. Taking the results together with our previous documentation of the mechanism for claudin strand assembly in a fibroblast model, we speculate that newly synthesized claudins are added at strand breaks and free ends; these are most common in the basalmost edge of the junction. In contrast, occludin can be added directly within the strand network. We further demonstrate that claudin trafficking and half-life depend on carboxy-terminal sequences and that different claudins compete for tight junction localization.
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Affiliation(s)
- Christina M Van Itallie
- Laboratory of Tight Junction Structure and Function, National Institutes of Health, Bethesda, MD 20892
| | - Karin Fredriksson Lidman
- Laboratory of Tight Junction Structure and Function, National Institutes of Health, Bethesda, MD 20892
| | - Amber Jean Tietgens
- Laboratory of Tight Junction Structure and Function, National Institutes of Health, Bethesda, MD 20892
| | - James Melvin Anderson
- Laboratory of Tight Junction Structure and Function, National Institutes of Health, Bethesda, MD 20892
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Abstract
The function of many proteins is intrinsically related to their cellular location. Novel methods for ascertainment of the ultrastructural location of proteins have been introduced in recent years, but their implementation in protists has so far not been readily realized. Here, we present an optimized proximity labeling protocol using the APEX system in the salmon pathogen Spironucleus salmonicida. This protocol was also applicable to the human pathogen Giardia intestinalis. Both organisms required extraneous addition of hemin to the growth medium to enable detectable peroxidase activity. Further, we saw no inherent limitation in labeling efficiency coupled to the cellular compartment, as evident with some other proximity labeling systems. We anticipate that the APEX proximity labeling system might offer a great resource to establish the ultrastructural localization of proteins across genetically tractable protists but might require organism-specific labeling conditions. The diplomonads are a group of understudied eukaryotic flagellates whose most prominent member is the human pathogen Giardia intestinalis. Methods commonly used in other eukaryotic model systems often require special optimization in diplomonads due to the highly derived character of their cell biology. We have optimized a proximity labeling protocol using pea ascorbate peroxidase (APEX) as a reporter for transmission electron microscopy (TEM) to enable the study of ultrastructural cellular details in diplomonads. Currently available TEM-compatible tags require light-induced activation (1, 2) or are inactive in many cellular compartments (3), while ascorbate peroxidase has not been shown to have those limitations. Here, we have optimized the in vivo activities of two versions of pea ascorbate peroxidase (APXW41F and APEX) using the diplomonad fish parasite Spironucleus salmonicida, a relative of G. intestinalis. We exploited the well-known peroxidase substrates, Amplex UltraRed and 3,3′-diaminobenzidine (DAB), to validate the activity of the two tags and argue that APEX is the most stable version to use in Spironucleus salmonicida. Next, we fused APEX to proteins with established localization to evaluate the activity of APEX in different cellular compartments of the diplomonad cell and used Amplex UltraRed as well as antibodies along with superresolution microscopy to confirm the protein-APEX localization. The ultrastructural details of protein-APEX fusions were determined by TEM, and we observed marker activity in all cellular compartments tested when using the DAB substrate. Finally, we show that the optimized conditions established for S. salmonicida can be used in the related diplomonad G. intestinalis. IMPORTANCE The function of many proteins is intrinsically related to their cellular location. Novel methods for ascertainment of the ultrastructural location of proteins have been introduced in recent years, but their implementation in protists has so far not been readily realized. Here, we present an optimized proximity labeling protocol using the APEX system in the salmon pathogen Spironucleus salmonicida. This protocol was also applicable to the human pathogen Giardia intestinalis. Both organisms required extraneous addition of hemin to the growth medium to enable detectable peroxidase activity. Further, we saw no inherent limitation in labeling efficiency coupled to the cellular compartment, as evident with some other proximity labeling systems. We anticipate that the APEX proximity labeling system might offer a great resource to establish the ultrastructural localization of proteins across genetically tractable protists but might require organism-specific labeling conditions.
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67
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Alcamí P, Pereda AE. Beyond plasticity: the dynamic impact of electrical synapses on neural circuits. Nat Rev Neurosci 2019; 20:253-271. [DOI: 10.1038/s41583-019-0133-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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68
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Defourny J, Thelen N, Thiry M. Actin-independent trafficking of cochlear connexin 26 to non-lipid raft gap junction plaques. Hear Res 2019; 374:69-75. [DOI: 10.1016/j.heares.2019.01.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 12/13/2018] [Accepted: 01/24/2019] [Indexed: 12/15/2022]
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69
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Tian X, Hussain S, de Pace C, Ruiz-Pérez L, Battaglia G. Zn II Complexes for Bioimaging and Correlated Applications. Chem Asian J 2019; 14:509-526. [PMID: 30716209 DOI: 10.1002/asia.201801437] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 12/31/2018] [Indexed: 11/09/2022]
Abstract
Zinc is a biocompatible element that exists as the second most abundant transition metal ion and an indispensable trace element in the human body. Compared to traditional metal-organic complexes systems, d10 metal ZnII complexes not only exhibit a large Stokes shift and good photon stability but also possess strong emission and low cytotoxicity with a relatively small molecular weight. The use of ZnII complexes has emerged in the last decade as a versatile and convenient tool for numerous biological applications, including bioimaging, molecular and protein recognition, as well as photodynamic therapy. Herein, we review recent developments involving ZnII metal complexes applied as specific subcellular compartment imaging probes and their correlated utilizations.
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Affiliation(s)
- Xiaohe Tian
- School of life science, Anhui University, Hefei, 230039, P.R. China
| | - Sajid Hussain
- School of life science, Anhui University, Hefei, 230039, P.R. China.,School of Applied Sciences and Humanities (NUSASH), National University of Technology, Sector I-12, Islamabad, Pakistan
| | - Cesare de Pace
- Department of Chemistry, University College London, London, WC1H 0AJ, UK
| | - Lorena Ruiz-Pérez
- Department of Chemistry, University College London, London, WC1H 0AJ, UK
| | - Giuseppe Battaglia
- School of life science, Anhui University, Hefei, 230039, P.R. China.,Department of Chemistry, University College London, London, WC1H 0AJ, UK
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70
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Cochlear connexin 30 homomeric and heteromeric channels exhibit distinct assembly mechanisms. Mech Dev 2019; 155:8-14. [DOI: 10.1016/j.mod.2018.10.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 10/04/2018] [Indexed: 01/01/2023]
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71
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Fluorescent labelling of membrane fatty acid transporter CD36 (SR-B2) in the extracellular loop. PLoS One 2019; 14:e0210704. [PMID: 30673728 PMCID: PMC6343965 DOI: 10.1371/journal.pone.0210704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 01/01/2019] [Indexed: 11/19/2022] Open
Abstract
Context Upon palmitate oversupply, membrane fatty acid-transporter CD36 (SR-B2) permanently translocates from endosomal storage to the sarcolemma, inducing lipotoxicity. CD36 translocation results from endosomal alkalinisation elicited by palmitate-induced disattachment of the cytoplasmic V1-subcomplex from the membrane-integrated V0-subcomplex of vacuolar-type H+-ATPase. Objective Develop a CD36 fluorescent labeling technique as initial step towards live cell imaging. Methods Three human CD36 (hCD36) mutants were constructed via insertion of a tetracysteine motif at different positions within the extracellular domain. Constructs were lentivirally transduced for subsequent CD36 labeling with fluorescein-arsenical hairpin-binder (FlAsH). Cell imaging was combined with V0/V1 immunostaining and Western blotting. Results Transduction of hCD36-wildtype and mutants yielded corresponding proteins in HL-1 cardiomyocytes. Tetracysteine mutant-2 (hCD36-TC2) showed similar fatty acid uptake to wildtype. FlAsH staining revealed a speckled pattern reminiscent of endosomes. We found decreased V1 co-localization with CD36 upon high-palmitate culturing. Conversely, V0 consistently co-localized with CD36. Conclusion hCD36-TC2 is a possible candidate for application of biarsenical dyes in live imaging studies pending further investigation. Our data is compatible with V0/V1 disassembly in high-palmitate-treated cells.
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72
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Pogoda K, Kameritsch P, Mannell H, Pohl U. Connexins in the control of vasomotor function. Acta Physiol (Oxf) 2019; 225:e13108. [PMID: 29858558 DOI: 10.1111/apha.13108] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 05/25/2018] [Accepted: 05/28/2018] [Indexed: 12/13/2022]
Abstract
Vascular endothelial cells, as well as smooth muscle cells, show heterogeneity with regard to their receptor expression and reactivity. For the vascular wall to act as a functional unit, the various cells' responses require integration. Such an integration is not only required for a homogeneous response of the vascular wall, but also for the vasomotor behaviour of consecutive segments of the microvascular arteriolar tree. As flow resistances of individual sections are connected in series, sections require synchronization and coordination to allow effective changes of conductivity and blood flow. A prerequisite for the local coordination of individual vascular cells and different sections of an arteriolar tree is intercellular communication. Connexins are involved in a dual manner in this coordination. (i) By forming gap junctions between cells, they allow an intercellular exchange of signalling molecules and electrical currents. In particular, the spread of electrical currents allows for coordination of cell responses over longer distances. (ii) Connexins are able to interact with other proteins to form signalling complexes. In this way, they can modulate and integrate individual cells' responses also in a channel-independent manner. This review outlines mechanisms allowing the vascular connexins to exert their coordinating function and to regulate the vasomotor reactions of blood vessels both locally, and in vascular networks. Wherever possible, we focus on the vasomotor behaviour of small vessels and arterioles which are the main vessels determining vascular resistance, blood pressure and local blood flow.
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Affiliation(s)
- K. Pogoda
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
| | - P. Kameritsch
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
| | - H. Mannell
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
| | - U. Pohl
- Walter-Brendel-Centre of Experimental Medicine; University Hospital; LMU Munich; Munich Germany
- Biomedical Center; Cardiovascular Physiology; LMU Munich; Munich Germany
- DZHK (German Center for Cardiovascular Research); Partner Site Munich Heart Alliance; Munich Germany
- Munich Cluster for Systems Neurology (SyNergy); Munich Germany
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73
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Gourdie RG. The Cardiac Gap Junction has Discrete Functions in Electrotonic and Ephaptic Coupling. Anat Rec (Hoboken) 2018; 302:93-100. [PMID: 30565418 DOI: 10.1002/ar.24036] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 07/10/2018] [Accepted: 07/17/2018] [Indexed: 12/31/2022]
Abstract
Connexin43-formed gap junctions have long been thought to contribute to cardiac conduction in the mammalian ventricle by providing direct electrotonic connectivity between the cytoplasms of neighboring cardiomyocytes. However, accumulating data from studies of non-mammalian hearts, Connexin 43 (Cx43) knockout mice and human Cx43 mutations have raised questions as to whether gap junctions are the sole means by which electrical coupling between cardiomyocytes is accomplished. Computational and experimental work over the last decade have indicated that intercellular propagation of action potentials in the heart may involve both electrotonic and ephaptic contributions-in what has been dubbed "mixed-mode" conduction. Interestingly, the Cx43 gap junction may provide a common structural platform in mammals that facilitates the operation of these two mechanisms. In addition to gap junction channels functioning in an electrotonic role, the perinexus region at the edge of gap junctions may be provide a niche for voltage-gated sodium channels from neighboring cells to be in sufficiently close proximity to enable ephaptic transmission of action potential. A novel role has recently been identified in this potential ephaptic mechanism for inter-membrane adhesion mediated by the beta subunit (beta1/Scn1b) of the sodium channel. The new perspective of the operational redundancy that is built into cardiac electrical connectivity could provide new understanding of arrhythmia mechanisms and holds the promise for new approach to anti-arrhythmic therapy. Anat Rec, 302:93-100, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Robert G Gourdie
- Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research Institute, Virginia Tech, Roanoke, Virginia, 24016.,Department of Emergency Medicine, Virginia Tech Carilion School of Medicine, Virginia Tech, Roanoke, Virginia, 24016.,Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, 24061
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74
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Valdez Capuccino JM, Chatterjee P, García IE, Botello-Smith WM, Zhang H, Harris AL, Luo Y, Contreras JE. The connexin26 human mutation N14K disrupts cytosolic intersubunit interactions and promotes channel opening. J Gen Physiol 2018; 151:328-341. [PMID: 30530766 PMCID: PMC6400520 DOI: 10.1085/jgp.201812219] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 10/21/2018] [Accepted: 11/17/2018] [Indexed: 01/06/2023] Open
Abstract
The N14K mutation in the N-terminal domain of connexin26 produces gain-of-function hemichannels. Valdez Capuccino et al. reveal that the mutation disrupts intersubunit interactions between the N terminus and the second transmembrane domain–cytoplasmic loop transition. A group of human mutations within the N-terminal (NT) domain of connexin 26 (Cx26) hemichannels produce aberrant channel activity, which gives rise to deafness and skin disorders, including keratitis-ichthyosis-deafness (KID) syndrome. Structural and functional studies indicate that the NT of connexin hemichannels is folded into the pore, where it plays important roles in permeability and gating. In this study, we explore the molecular basis by which N14K, an NT KID mutant, promotes gain of function. In macroscopic and single-channel recordings, we find that the N14K mutant favors the open conformation of hemichannels, shifts calcium and voltage sensitivity, and slows deactivation kinetics. Multiple copies of MD simulations of WT and N14K hemichannels, followed by the Kolmogorov–Smirnov significance test (KS test) of the distributions of interaction energies, reveal that the N14K mutation significantly disrupts pairwise interactions that occur in WT hemichannels between residue K15 of one subunit and residue E101 of the adjacent subunit (E101 being located at the transition between transmembrane segment 2 [TM2] and the cytoplasmic loop [CL]). Double mutant cycle analysis supports coupling between the NT and the TM2/CL transition in WT hemichannels, which is disrupted in N14K mutant hemichannels. KS tests of the α carbon correlation coefficients calculated over MD trajectories suggest that the effects of the N14K mutation are not confined to the K15–E101 pairs but extend to essentially all pairwise residue correlations between the NT and TM2/CL interface. Together, our data indicate that the N14K mutation increases hemichannel open probability by disrupting interactions between the NT and the TM2/CL region of the adjacent connexin subunit. This suggests that NT–TM2/CL interactions facilitate Cx26 hemichannel closure.
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Affiliation(s)
- Juan M Valdez Capuccino
- Department of Pharmacology, Physiology & Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ
| | - Payal Chatterjee
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA
| | - Isaac E García
- Laboratory of Molecular Physiology and Biophysics, Facultad de Odontología, Universidad de Valparaíso, Valparaíso, Chile.,Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Wesley M Botello-Smith
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA
| | - Han Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA
| | - Andrew L Harris
- Department of Pharmacology, Physiology & Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ
| | - Yun Luo
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA
| | - Jorge E Contreras
- Department of Pharmacology, Physiology & Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ .,Rutgers School of Graduate Studies, Newark, NJ
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75
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VIPER is a genetically encoded peptide tag for fluorescence and electron microscopy. Proc Natl Acad Sci U S A 2018; 115:12961-12966. [PMID: 30518560 DOI: 10.1073/pnas.1808626115] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many discoveries in cell biology rely on making specific proteins visible within their native cellular environment. There are various genetically encoded tags, such as fluorescent proteins, developed for fluorescence microscopy (FM). However, there are almost no genetically encoded tags that enable cellular proteins to be observed by both FM and electron microscopy (EM). Herein, we describe a technology for labeling proteins with diverse chemical reporters, including bright organic fluorophores for FM and electron-dense nanoparticles for EM. Our technology uses versatile interacting peptide (VIP) tags, a class of genetically encoded tag. We present VIPER, which consists of a coiled-coil heterodimer formed between the genetic tag, CoilE, and a probe-labeled peptide, CoilR. Using confocal FM, we demonstrate that VIPER can be used to highlight subcellular structures or to image receptor-mediated iron uptake. Additionally, we used VIPER to image the iron uptake machinery by correlative light and EM (CLEM). VIPER compared favorably with immunolabeling for imaging proteins by CLEM, and is an enabling technology for protein targets that cannot be immunolabeled. VIPER is a versatile peptide tag that can be used to label and track proteins with diverse chemical reporters observable by both FM and EM instrumentation.
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76
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Lynn BD, Li X, Hormuzdi SG, Griffiths EK, McGlade CJ, Nagy JI. E3 ubiquitin ligases LNX1 and LNX2 localize at neuronal gap junctions formed by connexin36 in rodent brain and molecularly interact with connexin36. Eur J Neurosci 2018; 48:3062-3081. [PMID: 30295974 DOI: 10.1111/ejn.14198] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 08/31/2018] [Accepted: 09/25/2018] [Indexed: 12/31/2022]
Abstract
Electrical synapses in the mammalian central nervous system (CNS) are increasingly recognized as highly complex structures for mediation of neuronal communication, both with respect to their capacity for dynamic short- and long-term modification in efficacy of synaptic transmission and their multimolecular regulatory and structural components. These two characteristics are inextricably linked, such that understanding of mechanisms that contribute to electrical synaptic plasticity requires knowledge of the molecular composition of electrical synapses and the functions of proteins associated with these synapses. Here, we provide evidence that the key component of gap junctions that form the majority of electrical synapses in the mammalian CNS, namely connexin36 (Cx36), directly interacts with the related E3 ubiquitin ligase proteins Ligand of NUMB protein X1 (LNX1) and Ligand of NUMB protein X2 (LNX2). This is based on immunofluorescence colocalization of LNX1 and LNX2 with Cx36-containing gap junctions in adult mouse brain versus lack of such coassociation in LNX null mice, coimmunoprecipitation of LNX proteins with Cx36, and pull-down of Cx36 with the second PDZ domain of LNX1 and LNX2. Furthermore, cotransfection of cultured cells with Cx36 and E3 ubiquitin ligase-competent LNX1 and LNX2 isoforms led to loss of Cx36-containing gap junctions between cells, whereas these junctions persisted following transfection with isoforms of these proteins that lack ligase activity. Our results suggest that a LNX protein mediates ubiquitination of Cx36 at neuronal gap junctions, with consequent Cx36 internalization, and may thereby contribute to intracellular mechanisms that govern the recently identified modifiability of synaptic transmission at electrical synapses.
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Affiliation(s)
- Bruce D Lynn
- Department of Physiology and Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Xinbo Li
- Casey Eye Institute, Oregon Health and Science University, Portland, Oregon
| | - Sheriar G Hormuzdi
- D'Arcy Thompson Unit, School of Life Sciences, University of Dundee, Dundee, UK
| | - Emily K Griffiths
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| | - C Jane McGlade
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| | - James I Nagy
- Department of Physiology and Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Science, University of Manitoba, Winnipeg, Manitoba, Canada
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77
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Abrams CK, Peinado A, Mahmoud R, Bocarsly M, Zhang H, Chang P, Botello-Smith WM, Freidin MM, Luo Y. Alterations at Arg 76 of human connexin 46, a residue associated with cataract formation, cause loss of gap junction formation but preserve hemichannel function. Am J Physiol Cell Physiol 2018; 315:C623-C635. [PMID: 30044662 DOI: 10.1152/ajpcell.00157.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The connexins are members of a family of integral membrane proteins that form gap junction channels between apposed cells and/or hemichannels across the plasma membranes. The importance of the arginine at position 76 (Arg76) in the structure and/or function of connexin 46 (Cx46) is highlighted by its conservation across the entire connexin family and the occurrence of pathogenic mutations at this (or the corresponding homologous) residue in a number of human diseases. Two mutations at Arg76 in Cx46 are associated with cataracts in humans, highlighting the importance of this residue. We examined the expression levels and macroscopic and single-channel properties of human Cx46 and compared them with those for two pathogenic mutants, namely R76H and R76G. To gain further insight into the role of charge at this position, we generated two additional nonnaturally occurring mutants, R76K (charge conserving) and R76E (charge inverting). We found that, when expressed exogenously in Neuro2a cells, all four mutants formed membrane hemichannels, inducing membrane permeability at levels comparable to those recorded in cells expressing the wild-type Cx46. In contrast, the number of gap-junction plaques and the magnitude of junctional coupling were reduced by all four mutations. To gain further insight into the role of Arg76 in the function of Cx46, we performed homology modeling of Cx46 and in silico mutagenesis of Arg76 to Gly, His, or Glu. Our studies suggest that the loss of interprotomeric interactions has a significant effect on the extracellular domain conformation and dynamics, thus affecting the hemichannel docking required for formation of cell-cell channels.
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Affiliation(s)
- Charles K Abrams
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine , Chicago, Illinois
- Department of Neurology State University of New York Downstate Medical Center , Brooklyn New York
| | - Alejandro Peinado
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine , Chicago, Illinois
| | - Rola Mahmoud
- Department of Neurology State University of New York Downstate Medical Center , Brooklyn New York
| | - Matan Bocarsly
- Department of Neurology State University of New York Downstate Medical Center , Brooklyn New York
| | - Han Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences , Pomona, California
| | - Paul Chang
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences , Pomona, California
| | - Wesley M Botello-Smith
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences , Pomona, California
| | - Mona M Freidin
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine , Chicago, Illinois
- Department of Neurology State University of New York Downstate Medical Center , Brooklyn New York
| | - Yun Luo
- Department of Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences , Pomona, California
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78
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Application of molecular dynamics simulations to design a dual-purpose oligopeptide linker sequence for fusion proteins. J Mol Model 2018; 24:313. [PMID: 30324504 DOI: 10.1007/s00894-018-3846-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 09/15/2018] [Indexed: 10/28/2022]
Abstract
Proteins are often monitored by combining a fluorescent polypeptide tag with the target protein. However, due to the high molecular weight and immunogenicity of such tags, they are not suitable choices for combining with fusion proteins such as immunotoxins. In this study, we designed a polypeptide sequence with a dual role (it acts as both a linker and a fluorescent probe) to use with fusion proteins. Two common fluorescent tag sequences based on tetracysteine were compared to a commonly used rigid linker as well as our proposed dual-purpose sequence. Computational investigations showed that the dual-purpose sequence was structurally stable and may be a good choice to use as both a linker and a fluorescence marker between two moieties in a fusion protein.
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79
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Abstract
The connexin family of channel-forming proteins is present in every tissue type in the human anatomy. Connexins are best known for forming clustered intercellular channels, structurally known as gap junctions, where they serve to exchange members of the metabolome between adjacent cells. In their single-membrane hemichannel form, connexins can act as conduits for the passage of small molecules in autocrine and paracrine signalling. Here, we review the roles of connexins in health and disease, focusing on the potential of connexins as therapeutic targets in acquired and inherited diseases as well as wound repair, while highlighting the associated clinical challenges.
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80
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Kells-Andrews RM, Margraf RA, Fisher CG, Falk MM. Connexin-43 K63-polyubiquitylation on lysines 264 and 303 regulates gap junction internalization. J Cell Sci 2018; 131:jcs.204321. [PMID: 30054380 DOI: 10.1242/jcs.204321] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 06/22/2018] [Indexed: 12/20/2022] Open
Abstract
Gap junctions (GJs) assembled from connexin (Cx) proteins allow direct cell-cell communication. While phosphorylation is known to regulate multiple GJ functions, much less is known about the role of ubiquitin in these processes. Using ubiquitylation-type-specific antibodies and Cx43 lysine-to-arginine mutants we show that ∼8% of a GJ, localized in central plaque domains, is K63-polyubiquitylated on K264 and K303. Levels and localization of ubiquitylation correlated well with: (1) the short turnover rate of Cxs and GJs; (2) removal of older channels from the plaque center; and (3) the fact that not all Cxs in an internalizing GJ channel need to be ubiquitylated. Connexins mutated at these two sites assembled significantly larger GJs, exhibited much longer protein half-lives and were internalization impaired. Interestingly, these ubiquitin-deficient Cx43 mutants accumulated as hyper-phosphorylated polypeptides in the plasma membrane, suggesting that K63-polyubiquitylation is triggered by phosphorylation. Phospho-specific anti-Cx43 antibodies revealed that upregulated phosphorylation affected serines 368, 279/282 and 255, which are well-known regulatory PKC and MAPK sites. Together, these novel findings suggest that the internalizing portion of channels in a GJ is K63-polyubiquitylated, ubiquitylation is critical for GJ internalization and that phosphorylation induces Cx K63-polyubiquitylation.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Rachael M Kells-Andrews
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Iacocca Hall, Bethlehem, PA 18015, USA
| | - Rachel A Margraf
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Iacocca Hall, Bethlehem, PA 18015, USA
| | - Charles G Fisher
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Iacocca Hall, Bethlehem, PA 18015, USA
| | - Matthias M Falk
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Iacocca Hall, Bethlehem, PA 18015, USA
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81
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Jabeen S, Thirumalai V. The interplay between electrical and chemical synaptogenesis. J Neurophysiol 2018; 120:1914-1922. [PMID: 30067121 PMCID: PMC6230774 DOI: 10.1152/jn.00398.2018] [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] [Indexed: 12/22/2022] Open
Abstract
Neurons communicate with each other via electrical or chemical synaptic connections. The pattern and strength of connections between neurons are critical for generating appropriate output. What mechanisms govern the formation of electrical and/or chemical synapses between two neurons? Recent studies indicate that common molecular players could regulate the formation of both of these classes of synapses. In addition, electrical and chemical synapses can mutually coregulate each other’s formation. Electrical activity, generated spontaneously by the nervous system or initiated from sensory experience, plays an important role in this process, leading to the selection of appropriate connections and the elimination of inappropriate ones. In this review, we discuss recent studies that shed light on the formation and developmental interactions of chemical and electrical synapses.
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Affiliation(s)
- Shaista Jabeen
- National Centre for Biological Sciences, Tata Institute for Fundamental Research , Bangalore , India.,Manipal Academy of Higher Education, Madhav Nagar, Manipal , India
| | - Vatsala Thirumalai
- National Centre for Biological Sciences, Tata Institute for Fundamental Research , Bangalore , India
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82
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Hussain A, Das Sarma S, Babu S, Pal D, Das Sarma J. Interaction of arsenic with gap junction protein connexin 43 alters gap junctional intercellular communication. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2018; 1865:1423-1436. [PMID: 30031898 DOI: 10.1016/j.bbamcr.2018.07.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 07/09/2018] [Accepted: 07/17/2018] [Indexed: 11/18/2022]
Abstract
Chronic exposure to Arsenic pollution in ground water is one of the largest environmental health disasters in the world. The toxicity of trivalent Arsenicals primarily happens due to its interaction with sulfhydryl groups in proteins. Arsenic binding to the protein can change the conformation of the protein and alter its interactions with other proteins leading to tissue damage. Therefore, much importance has been given to the studies of Arsenic bound proteins, for the purpose of understanding the origins of toxicity and to explore therapeutics. Here we study the dynamic effect of Arsenic on Connexin 43 (Cx43), a protein that forms the gap junctions, whose alteration deeply perturbs the cell-to-cell communication vital for maintaining tissue homeostasis. In silico molecular modelling and in vitro studies comparing Arsenic treated and untreated conditions show distinct results. Gap junction communication is severely disrupted by Arsenic due to reduced availability of unaltered Cx43 in the membrane bound form. In silico and Inductively Coupled Plasma Mass Spectrometry studies revealed the interaction of Arsenic to the Cx43 preferably occurs through surface exposed cysteines, thereby capping the thiol groups that form disulfide bonds in the tertiary structure. This leads to disruption of Cx43 oligomerization, and altered Cx43 is incompetent for transportation to the membrane surface, often forming aggregates primarily localizing in the endoplasmic reticulum. Loss of functional Cx43 on the cell surface have a deleterious effect on cellular homeostasis leading to selective vulnerability to cell death and tissue damage.
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Affiliation(s)
- Afaq Hussain
- Department of Biological Sciences, Indian Institute of Science Education & Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Subhajit Das Sarma
- Department of Biological Sciences, Indian Institute of Science Education & Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Swathy Babu
- Department of Biological Sciences, Indian Institute of Science Education & Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Debnath Pal
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - Jayasri Das Sarma
- Department of Biological Sciences, Indian Institute of Science Education & Research Kolkata, Mohanpur 741246, West Bengal, India.
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83
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Lysova I, Spiegelhalter C, Réal E, Zgheib S, Anton H, Mély Y. ReAsH/tetracystein-based correlative light-electron microscopy for HIV-1 imaging during the early stages of infection. Methods Appl Fluoresc 2018; 6:045001. [PMID: 29938685 DOI: 10.1088/2050-6120/aacec1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Visualization of viruses in the host cell during the course of infection by correlative light-electron microscopy (CLEM) requires a specific labelling of the viral structures in order to recognize the nanometric viral cores in the intracellular environment. For Human immunodeficiency virus type 1 (HIV-1), the labelling approaches developed for fluorescence microscopy are generally not suited for transmission electron microscopy (TEM), so that imaging of HIV-1 particles in infected cells by CLEM is not straightforward. Herein, we adapt the labeling approach with a tetracystein tag (TC) and a biarsenical resorufin-based label (ReAsH) for monitoring the HIV-1 particles during the early stages of HIV-1 infection by CLEM. In this approach, the ReAsH fluorophore triggers the photo-conversion of 3,3-diaminobenzidine tetrahydrochloride (DAB), generating a precipitate sensitive to osmium tetroxide staining that can be visualized by transmission electron microscopy. The TC tag is fused to the nucleocapsid protein NCp7, a nucleic acid chaperone that binds to the viral genome. HeLa cells, infected by ReAsH-labeled pseudoviruses containg NCp7-TC proteins exhibit strong fluorescent cytoplasmic spots that overlap with dark precipitates in the TEM sections. The DAB precipitates corresponding to single viral cores are observed all over the cytoplasm, and notably near microtubules and nuclear pores. This work describes for the first time a specific contrast given by HIV-1 viral proteins in TEM images and opens new perspectives for the use of CLEM to monitor the intracellular traffic of viral complexes.
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Affiliation(s)
- Iryna Lysova
- Laboratoire de Bioimagerie et Pathologies, CNRS UMR 7021, Strasbourg University, Faculty of Pharmacy, 74 route du Rhin, Illkirch, France
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84
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Clarke NI, Royle SJ. FerriTag is a new genetically-encoded inducible tag for correlative light-electron microscopy. Nat Commun 2018; 9:2604. [PMID: 29973588 PMCID: PMC6031641 DOI: 10.1038/s41467-018-04993-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 05/24/2018] [Indexed: 01/20/2023] Open
Abstract
A current challenge is to develop tags to precisely visualize proteins in cells by light and electron microscopy. Here, we introduce FerriTag, a genetically-encoded chemically-inducible tag for correlative light-electron microscopy. FerriTag is a fluorescent recombinant electron-dense ferritin particle that can be attached to a protein-of-interest using rapamycin-induced heterodimerization. We demonstrate the utility of FerriTag for correlative light-electron microscopy by labeling proteins associated with various intracellular structures including mitochondria, plasma membrane, and clathrin-coated pits and vesicles. FerriTagging has a good signal-to-noise ratio and a labeling resolution of approximately 10 nm. We demonstrate how FerriTagging allows nanoscale mapping of protein location relative to a subcellular structure, and use it to detail the distribution and conformation of huntingtin-interacting protein 1 related (HIP1R) in and around clathrin-coated pits.
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Affiliation(s)
- Nicholas I Clarke
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Stephen J Royle
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Gibbet Hill Road, Coventry, CV4 7AL, UK.
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85
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Wang L, Dou W, Malhi M, Zhu M, Liu H, Plakhotnik J, Xu Z, Zhao Q, Chen J, Chen S, Hamilton R, Simmons CA, Maynes JT, Sun Y. Microdevice Platform for Continuous Measurement of Contractility, Beating Rate, and Beating Rhythm of Human-Induced Pluripotent Stem Cell-Cardiomyocytes inside a Controlled Incubator Environment. ACS APPLIED MATERIALS & INTERFACES 2018; 10:21173-21183. [PMID: 29874032 DOI: 10.1021/acsami.8b05407] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The heart completes a complex set of tasks, including the initiation or propagation of an electrical signal with regularity (proper heart rate and rhythm) and generating sufficient force of contraction (contractility). Probing mechanisms of heart diseases and quantifying drug efficacies demand a platform that is capable of continuous operation inside a cell incubator for long-term measurement of cardiomyocyte (CM) monolayers. Here, we report a microdevice array that is capable of performing continuous, long-term (14 days) measurement of contractility, beating rate, and beating rhythm in a monolayer of human-induced pluripotent stem cell-CMs (hiPSC-CMs). The device consists of a deformable membrane with embedded carbon nanotube (CNT)-based strain sensors. Contraction of the hiPSC-CMs seeded on the membrane induces electrical resistance change of the CNT strain sensor. Continuously reading the sensor signals revealed that hiPSC-CMs started to beat from day 2 and plateaued on day 5. Average contractile stress generated by a monolayer of hiPSC-CMs was determined to be 2.34 ± 0.041 kPa with a beating rate of 1.17 ± 0.068 Hz. The device arrays were also used to perform comprehensive measurement of the beating rate, rhythm, and contractility of the hiPSC-CMs and quantify the cell responses to different concentrations of agonists and antagonists, which altered the average contractile stress to the range of 1.15 ± 0.13 to 3.96 ± 0.53 kPa. The continuous measurement capability of the device arrays also enabled the generation of Poincaré plots for revealing subtle changes in the beating rhythm of hiPSC-CMs under different drug treatments.
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Affiliation(s)
- Li Wang
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
| | - Wenkun Dou
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
| | - Manpreet Malhi
- Hospital for Sick Children , Toronto ON M5G 1X8 , Canada
| | - Min Zhu
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
| | - Haijiao Liu
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
- Institute of Biomaterials and Biomedical Engineering , University of Toronto , Toronto ON M5S 3G9 , Canada
| | | | - Zhensong Xu
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
| | - Qili Zhao
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
| | - Jun Chen
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
| | - Siyu Chen
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
| | | | - Craig A Simmons
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
- Institute of Biomaterials and Biomedical Engineering , University of Toronto , Toronto ON M5S 3G9 , Canada
| | - Jason T Maynes
- Hospital for Sick Children , Toronto ON M5G 1X8 , Canada
| | - Yu Sun
- Department of Mechanical and Industrial Engineering , University of Toronto , Toronto ON M5S 3G8 , Canada
- Institute of Biomaterials and Biomedical Engineering , University of Toronto , Toronto ON M5S 3G9 , Canada
- Department of Electrical and Computer Engineering , University of Toronto , Toronto ON M5S 3G4 , Canada
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86
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Frequent pauses in Escherichia coli flagella elongation revealed by single cell real-time fluorescence imaging. Nat Commun 2018; 9:1885. [PMID: 29760469 PMCID: PMC5951861 DOI: 10.1038/s41467-018-04288-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 04/13/2018] [Indexed: 12/02/2022] Open
Abstract
The bacterial flagellum is a large extracellular protein organelle that extrudes from the cell surface. The flagellar filament is assembled from tens of thousands of flagellin subunits that are exported through the flagellar type III secretion system. Here, we measure the growth of Escherichia coli flagella in real time and find that, although the growth rate displays large variations at similar lengths, it decays on average as flagella lengthen. By tracking single flagella, we show that the large variations in growth rate occur as a result of frequent pauses. Furthermore, different flagella on the same cell show variable growth rates with correlation. Our observations are consistent with an injection-diffusion model, and we propose that an insufficient cytoplasmic flagellin supply is responsible for the pauses in flagellar growth in E. coli. The bacterial flagellar filament is assembled from tens of thousands of flagellin subunits that are exported by a dedicated secretion system. Here, the authors show that, on average, the growth rate of flagella in E. coli decays as flagella lengthen, with large variations due to frequent pauses.
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87
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Tsang TK, Bushong EA, Boassa D, Hu J, Romoli B, Phan S, Dulcis D, Su CY, Ellisman MH. High-quality ultrastructural preservation using cryofixation for 3D electron microscopy of genetically labeled tissues. eLife 2018; 7:35524. [PMID: 29749931 PMCID: PMC5988420 DOI: 10.7554/elife.35524] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 05/09/2018] [Indexed: 02/06/2023] Open
Abstract
Electron microscopy (EM) offers unparalleled power to study cell substructures at the nanoscale. Cryofixation by high-pressure freezing offers optimal morphological preservation, as it captures cellular structures instantaneously in their near-native state. However, the applicability of cryofixation is limited by its incompatibility with diaminobenzidine labeling using genetic EM tags and the high-contrast en bloc staining required for serial block-face scanning electron microscopy (SBEM). In addition, it is challenging to perform correlated light and electron microscopy (CLEM) with cryofixed samples. Consequently, these powerful methods cannot be applied to address questions requiring optimal morphological preservation. Here, we developed an approach that overcomes these limitations; it enables genetically labeled, cryofixed samples to be characterized with SBEM and 3D CLEM. Our approach is broadly applicable, as demonstrated in cultured cells, Drosophila olfactory organ and mouse brain. This optimization exploits the potential of cryofixation, allowing for quality ultrastructural preservation for diverse EM applications.
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Affiliation(s)
- Tin Ki Tsang
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Eric A Bushong
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States
| | - Daniela Boassa
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States
| | - Junru Hu
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States
| | - Benedetto Romoli
- Department of Psychiatry, School of Medicine, University of California, San Diego, La Jolla, United States
| | - Sebastien Phan
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States
| | - Davide Dulcis
- Department of Psychiatry, School of Medicine, University of California, San Diego, La Jolla, United States
| | - Chih-Ying Su
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States.,Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, United States
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88
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Gatterdam K, Joest EF, Dietz MS, Heilemann M, Tampé R. Super-Chelators for Advanced Protein Labeling in Living Cells. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201800827] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Karl Gatterdam
- Institute of Biochemistry; Biocenter; Goethe-University Frankfurt; Max-von-Laue-Str. 9 60438 Frankfurt/M Germany
| | - Eike F. Joest
- Institute of Biochemistry; Biocenter; Goethe-University Frankfurt; Max-von-Laue-Str. 9 60438 Frankfurt/M Germany
| | - Marina S. Dietz
- Institute of Physical and Theoretical Chemistry; Goethe-University Frankfurt; Max-von-Laue-Str. 9 60438 Frankfurt/M Germany
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry; Goethe-University Frankfurt; Max-von-Laue-Str. 9 60438 Frankfurt/M Germany
| | - Robert Tampé
- Institute of Biochemistry; Biocenter; Goethe-University Frankfurt; Max-von-Laue-Str. 9 60438 Frankfurt/M Germany
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89
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Gatterdam K, Joest EF, Dietz MS, Heilemann M, Tampé R. Super-Chelators for Advanced Protein Labeling in Living Cells. Angew Chem Int Ed Engl 2018; 57:5620-5625. [PMID: 29464841 DOI: 10.1002/anie.201800827] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 02/17/2018] [Indexed: 12/17/2022]
Abstract
Live-cell labeling, super-resolution microscopy, single-molecule applications, protein localization, or chemically induced assembly are emerging approaches, which require specific and very small interaction pairs. The minimal disturbance of protein function is essential to derive unbiased insights into cellular processes. Herein, we define a new class of hexavalent N-nitrilotriacetic acid (hexaNTA) chelators, displaying the highest affinity and stability of all NTA-based small interaction pairs described so far. Coupled to bright organic fluorophores with fine-tuned photophysical properties, the super-chelator probes were delivered into human cells by chemically gated nanopores. These super-chelators permit kinetic profiling, multiplexed labeling of His6 - and His12 -tagged proteins as well as single-molecule-based super-resolution imaging.
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Affiliation(s)
- Karl Gatterdam
- Institute of Biochemistry, Biocenter, Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt/M, Germany
| | - Eike F Joest
- Institute of Biochemistry, Biocenter, Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt/M, Germany
| | - Marina S Dietz
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt/M, Germany
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt/M, Germany
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe-University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt/M, Germany
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90
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García IE, Villanelo F, Contreras GF, Pupo A, Pinto BI, Contreras JE, Pérez-Acle T, Alvarez O, Latorre R, Martínez AD, González C. The syndromic deafness mutation G12R impairs fast and slow gating in Cx26 hemichannels. J Gen Physiol 2018; 150:697-711. [PMID: 29643172 PMCID: PMC5940247 DOI: 10.1085/jgp.201711782] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 11/13/2017] [Accepted: 03/21/2018] [Indexed: 12/27/2022] Open
Abstract
Mutations in connexin 26 hemichannels that cause syndromic deafness have a gain-of-function phenotype that is poorly understood. García et al. show that one such mutation impairs fast and slow gating in these hemichannels because of an interaction between the N terminus and intracellular loop. Mutations in connexin 26 (Cx26) hemichannels can lead to syndromic deafness that affects the cochlea and skin. These mutations lead to gain-of-function hemichannel phenotypes by unknown molecular mechanisms. In this study, we investigate the biophysical properties of the syndromic mutant Cx26G12R (G12R). Unlike wild-type Cx26, G12R macroscopic hemichannel currents do not saturate upon depolarization, and deactivation is faster during hyperpolarization, suggesting that these channels have impaired fast and slow gating. Single G12R hemichannels show a large increase in open probability, and transitions to the subconductance state are rare and short-lived, demonstrating an inoperative fast gating mechanism. Molecular dynamics simulations indicate that G12R causes a displacement of the N terminus toward the cytoplasm, favoring an interaction between R12 in the N terminus and R99 in the intracellular loop. Disruption of this interaction recovers the fast and slow voltage-dependent gating mechanisms. These results suggest that the mechanisms of fast and slow gating in connexin hemichannels are coupled and provide a molecular mechanism for the gain-of-function phenotype displayed by the syndromic G12R mutation.
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Affiliation(s)
- Isaac E García
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Laboratory of Molecular Physiology and Biophysics, Facultad de Odontología, Universidad de Valparaíso, Valparaíso, Chile
| | - Felipe Villanelo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Computational Biology Laboratory, Fundación Ciencia & Vida, Santiago, Chile
| | - Gustavo F Contreras
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Amaury Pupo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Bernardo I Pinto
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Jorge E Contreras
- Department of Pharmacology, Physiology, and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ
| | - Tomás Pérez-Acle
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Computational Biology Laboratory, Fundación Ciencia & Vida, Santiago, Chile
| | - Osvaldo Alvarez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Agustín D Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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91
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Abstract
Chemically constructed biosensors consisting of a protein scaffold and an artificial small molecule have recently been recognized as attractive analytical tools for the specific detection and real-time monitoring of various biological substances or events in cells. Conventionally, such semisynthetic biosensors have been prepared in test tubes and then introduced into cells using invasive methods. With the impressive advances seen in bioorthogonal protein conjugation methodologies, however, it is now becoming feasible to directly construct semisynthetic biosensors in living cells, providing unprecedented tools for life-science research. We discuss here recent efforts regarding the in situ construction of protein-based semisynthetic biosensors and highlight their uses in the visualization and quantification of biomolecules and events in multimolecular and crowded cellular systems.
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Affiliation(s)
- Tsuyoshi Ueda
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Tomonori Tamura
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Itaru Hamachi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
- CREST(Core Research for Evolutional Science and Technology, JST), Sanbancho, Chiyodaku, Tokyo, 102-0075, Japan
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92
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Davis CM, Gruebele M. Labeling for Quantitative Comparison of Imaging Measurements in Vitro and in Cells. Biochemistry 2018; 57:1929-1938. [PMID: 29546761 DOI: 10.1021/acs.biochem.8b00141] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Qualitative imaging of biomolecular localization and distribution inside cells has revolutionized cell biology. Most of these powerful techniques require modifications to the target biomolecule. Over the past 10 years, these techniques have been extended to quantitative measurements, from in-cell protein folding rates to complex dissociation constants to RNA lifetimes. Such measurements can be affected even when a target molecule is just mildly perturbed by its labels. Here, the impact of labeling on protein (and RNA) structure, stability, and function in cells is discussed via practical examples from the recent literature. General guidelines for selecting and validating modification sites are provided to bring the best from cell biology and imaging to quantitative biophysical experiments inside cells.
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93
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Abstract
Cortical oscillations are thought to be involved in many cognitive functions and processes. Several mechanisms have been proposed to regulate oscillations. One prominent but understudied mechanism is gap junction coupling. Gap junctions are ubiquitous in cortex between GABAergic interneurons. Moreover, recent experiments indicate their strength can be modified in an activity-dependent manner, similar to chemical synapses. We hypothesized that activity-dependent gap junction plasticity acts as a mechanism to regulate oscillations in the cortex. We developed a computational model of gap junction plasticity in a recurrent cortical network based on recent experimental findings. We showed that gap junction plasticity can serve as a homeostatic mechanism for oscillations by maintaining a tight balance between two network states: asynchronous irregular activity and synchronized oscillations. This homeostatic mechanism allows for robust communication between neuronal assemblies through two different mechanisms: transient oscillations and frequency modulation. This implies a direct functional role for gap junction plasticity in information transmission in cortex.
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Affiliation(s)
- Guillaume Pernelle
- Bioengineering Department, Imperial College London, London, United Kingdom
| | - Wilten Nicola
- Bioengineering Department, Imperial College London, London, United Kingdom
| | - Claudia Clopath
- Bioengineering Department, Imperial College London, London, United Kingdom
- * E-mail:
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94
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Ray A, Katoch P, Jain N, Mehta PP. Dileucine-like motifs in the C-terminal tail of connexin32 control its endocytosis and assembly into gap junctions. J Cell Sci 2018; 131:jcs207340. [PMID: 29361528 PMCID: PMC5897717 DOI: 10.1242/jcs.207340] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 01/11/2018] [Indexed: 12/11/2022] Open
Abstract
Defects in assembly of gap junction-forming proteins, called connexins (Cxs), are observed in a variety of cancers. Connexin32 (Cx32; also known as GJB1) is expressed by the polarized cells in epithelia. We discovered two dileucine-based motifs, which govern the intracellular sorting and endocytosis of transmembrane proteins, in the C-terminal tail of Cx32 and explored their role in regulating its endocytosis and gap junction-forming abilities in pancreatic and prostate cancer cells. One motif, designated as LI, was located near the juxtamembrane domain, whereas the other, designated as LL, was located distally. We also discovered a non-canonical motif, designated as LR, in the C-terminal tail. Our results showed that rendering these motifs non-functional had no effect on the intracellular sorting of Cx32. However, rendering the LL or LR motif nonfunctional enhanced the formation of gap junctions by inhibiting Cx32 endocytosis by the clathrin-mediated pathway. Rendering the LI motif nonfunctional inhibited gap junction formation by augmenting the endocytosis of Cx32 via the LL and LR motifs. Our studies have defined distinct roles of these motifs in regulating the endocytosis of Cx32 and its gap junction-forming ability.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Anuttoma Ray
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Parul Katoch
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Nimansha Jain
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Parmender P Mehta
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
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95
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Abstract
Purpose of Review Considerable progress has been made in the field of stem cell research; nonetheless, the use of stem cells for regenerative medicine therapies, for either endogenous tissue repair or cellular grafts post injury, remains a challenge. To better understand how to maintain stem cell potential in vivo and promote differentiation ex vivo, it is fundamentally important to elucidate the interactions between stem cells and their surrounding partners within their distinct niches. Recent Findings Among the vast array of proteins depicted as mediators for cell-to-cell interactions, connexin-comprised gap junctions play pivotal roles in the regulation of stem cell fate both in vivo and in vitro. Summary This review summarizes and illustrates the current knowledge regarding the multifaceted roles of Cx43, specifically, in various stem cell niches.
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Affiliation(s)
- Nafiisha Genet
- Department of Medicine, Genetics and Biomedical Engineering, Yale Cardiovascular Research Center, Vascular Biology Therapeutics Program, New Haven, USA.,2Yale Stem Cell Center Yale University School of Medicine, 300 George St, New Haven, CT 06511 USA
| | - Neha Bhatt
- Department of Medicine, Genetics and Biomedical Engineering, Yale Cardiovascular Research Center, Vascular Biology Therapeutics Program, New Haven, USA.,2Yale Stem Cell Center Yale University School of Medicine, 300 George St, New Haven, CT 06511 USA
| | - Antonin Bourdieu
- Department of Medicine, Genetics and Biomedical Engineering, Yale Cardiovascular Research Center, Vascular Biology Therapeutics Program, New Haven, USA.,2Yale Stem Cell Center Yale University School of Medicine, 300 George St, New Haven, CT 06511 USA
| | - Karen K Hirschi
- Department of Medicine, Genetics and Biomedical Engineering, Yale Cardiovascular Research Center, Vascular Biology Therapeutics Program, New Haven, USA.,2Yale Stem Cell Center Yale University School of Medicine, 300 George St, New Haven, CT 06511 USA
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96
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Moghaddam-Taaheri P, Karlsson AJ. Protein Labeling in Live Cells for Immunological Applications. Bioconjug Chem 2018; 29:680-685. [DOI: 10.1021/acs.bioconjchem.7b00722] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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97
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Garciarena CD, Malik A, Swietach P, Moreno AP, Vaughan-Jones RD. Distinct moieties underlie biphasic H + gating of connexin43 channels, producing a pH optimum for intercellular communication. FASEB J 2018; 32:1969-1981. [PMID: 29183963 PMCID: PMC5893178 DOI: 10.1096/fj.201700876r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Most mammalian cells can intercommunicate via connexin-assembled, gap-junctional channels. To regulate signal transmission, connexin (Cx) channel permeability must respond dynamically to physiological and pathophysiological stimuli. One key stimulus is intracellular pH (pHi), which is modulated by a tissue’s metabolic and perfusion status. Our understanding of the molecular mechanism of H+ gating of Cx43 channels—the major isoform in the heart and brain—is incomplete. To interrogate the effects of acidic and alkaline pHi on Cx43 channels, we combined voltage-clamp electrophysiology with pHi imaging and photolytic H+ uncaging, performed over a range of pHi values. We demonstrate that Cx43 channels expressed in HeLa or N2a cell pairs are gated biphasically by pHivia a process that consists of activation by H+ ions at alkaline pHi and inhibition at more acidic pHi. For Cx43 channel–mediated solute/ion transmission, the ensemble of these effects produces a pHi optimum, near resting pHi. By using Cx43 mutants, we demonstrate that alkaline gating involves cysteine residues of the C terminus and is independent of motifs previously implicated in acidic gating. Thus, we present a molecular mechanism by which cytoplasmic acid–base chemistry fine tunes intercellular communication and establishes conditions for the optimal transmission of solutes and signals in tissues, such as the heart and brain.—Garciarena, C. D., Malik, A., Swietach, P., Moreno, A. P., Vaughan-Jones, R. D. Distinct moieties underlie biphasic H+ gating of connexin43 channels, producing a pH optimum for intercellular communication.
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Affiliation(s)
- Carolina D Garciarena
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom.,Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Akif Malik
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom
| | - Pawel Swietach
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom
| | - Alonso P Moreno
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, USA
| | - Richard D Vaughan-Jones
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Oxford, United Kingdom
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98
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Vicario N, Zappalà A, Calabrese G, Gulino R, Parenti C, Gulisano M, Parenti R. Connexins in the Central Nervous System: Physiological Traits and Neuroprotective Targets. Front Physiol 2017; 8:1060. [PMID: 29326598 PMCID: PMC5741605 DOI: 10.3389/fphys.2017.01060] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 12/04/2017] [Indexed: 01/22/2023] Open
Abstract
Cell-to-cell interaction and cell-to-extracellular environment communication are emerging as new therapeutic targets in neurodegenerative disorders. Dynamic expression of connexins leads to distinctive hemichannels and gap junctions, characterized by cell-specific conduction, exchange of stimuli or metabolites, and particular channel functions. Herein, we briefly reviewed classical physiological traits and functions of connexins, hemichannels, and gap junctions, in order to discuss the controversial role of these proteins and their mediated interactions during neuroprotection, with a particular focus on Cx43-based channels. We pointed out the contribution of connexins in neural cells populations during neurodegenerative processes to explore potential neuroprotective therapeutic applications.
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Affiliation(s)
- Nunzio Vicario
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Agata Zappalà
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Giovanna Calabrese
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rosario Gulino
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Carmela Parenti
- Department of Drug Sciences, University of Catania, Catania, Italy
| | - Massimo Gulisano
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy.,Department of Drug Sciences, University of Catania, Catania, Italy
| | - Rosalba Parenti
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
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99
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Tuomi JM, Xenocostas A, Jones DL. Increased Susceptibility for Atrial and Ventricular Cardiac Arrhythmias in Mice Treated With a Single High Dose of Ibrutinib. Can J Cardiol 2017; 34:337-341. [PMID: 29475534 DOI: 10.1016/j.cjca.2017.12.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 12/01/2017] [Accepted: 12/01/2017] [Indexed: 12/14/2022] Open
Abstract
Atrial fibrillation is a side effect of ibrutinib, an irreversible inhibitor of Bruton tyrosine kinase used for treatment of B-cell lymphoproliferative disorders. We determined if single (2 or 10 mg/kg), or chronic (14 days) oral ibrutinib followed by 24-hour washout conferred susceptibility to electrically induced arrhythmias in 1-month-old male C57BL/6 mice. A single higher dose of ibrutinib increased arrhythmia inducibility. There was no inducibility difference after chronic dosing with washout. This suggests that high serum drug levels might be responsible for the proarrhythmic effect of ibrutinib and that an altered dosing strategy might mitigate the side effects.
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Affiliation(s)
- Jari M Tuomi
- Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Anargyros Xenocostas
- Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Douglas L Jones
- Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
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100
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Schneider JP, Basler M. Shedding light on biology of bacterial cells. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0499. [PMID: 27672150 PMCID: PMC5052743 DOI: 10.1098/rstb.2015.0499] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2016] [Indexed: 12/11/2022] Open
Abstract
To understand basic principles of living organisms one has to know many different properties of all cellular components, their mutual interactions but also their amounts and spatial organization. Live-cell imaging is one possible approach to obtain such data. To get multiple snapshots of a cellular process, the imaging approach has to be gentle enough to not disrupt basic functions of the cell but also have high temporal and spatial resolution to detect and describe the changes. Light microscopy has become a method of choice and since its early development over 300 years ago revolutionized our understanding of living organisms. As most cellular components are indistinguishable from the rest of the cellular contents, the second revolution came from a discovery of specific labelling techniques, such as fusions to fluorescent proteins that allowed specific tracking of a component of interest. Currently, several different tags can be tracked independently and this allows us to simultaneously monitor the dynamics of several cellular components and from the correlation of their dynamics to infer their respective functions. It is, therefore, not surprising that live-cell fluorescence microscopy significantly advanced our understanding of basic cellular processes. Current cameras are fast enough to detect changes with millisecond time resolution and are sensitive enough to detect even a few photons per pixel. Together with constant improvement of properties of fluorescent tags, it is now possible to track single molecules in living cells over an extended period of time with a great temporal resolution. The parallel development of new illumination and detection techniques allowed breaking the diffraction barrier and thus further pushed the resolution limit of light microscopy. In this review, we would like to cover recent advances in live-cell imaging technology relevant to bacterial cells and provide a few examples of research that has been possible due to imaging. This article is part of the themed issue ‘The new bacteriology’.
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Affiliation(s)
- Johannes P Schneider
- Focal Area Infection Biology, Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, 4056 Basel, Switzerland
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