1
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Yu Z, Wang Z, Liu L. Electrophysiological techniques in marine microalgae study: A new perspective for harmful algal bloom (HAB) research. HARMFUL ALGAE 2024; 134:102629. [PMID: 38705615 DOI: 10.1016/j.hal.2024.102629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 04/11/2024] [Accepted: 04/15/2024] [Indexed: 05/07/2024]
Abstract
Electrophysiological techniques, by measuring bioelectrical signals and ion channel activities in tissues and cells, are now widely utilized to study ion channel-related physiological functions and their underlying mechanisms. Electrophysiological techniques have been extensively employed in the investigation of animals, plants, and microorganisms; however, their application in marine algae lags behind that in other organisms. In this paper, we present an overview of current electrophysiological techniques applicable to algae while reviewing the historical usage of such techniques in this field. Furthermore, we explore the potential specific applications of electrophysiological technology in harmful algal bloom (HAB) research. The application prospects in the studies of stress tolerance, competitive advantage, nutrient absorption, toxin synthesis and secretion by HAB microalgae are discussed and anticipated herein with the aim of providing novel perspectives on HAB investigations.
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Affiliation(s)
- Zhiming Yu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao, 266237, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Zhongshi Wang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao, 266237, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Lidong Liu
- The Djavad Mowafaghian Centre for Brian Health and Department of Medicine, University of British Columbia, Vancouver, BC, Canada
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2
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Tamucci JD, Alder NN, May ER. Peptide Power: Mechanistic Insights into the Effect of Mitochondria-Targeted Tetrapeptides on Membrane Electrostatics from Molecular Simulations. Mol Pharm 2023; 20:6114-6129. [PMID: 37904323 PMCID: PMC10841697 DOI: 10.1021/acs.molpharmaceut.3c00480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2023]
Abstract
Mitochondrial dysfunction is implicated in nine of the ten leading causes of death in the US, yet there are no FDA-approved therapeutics to treat it. Synthetic mitochondria-targeted peptides (MTPs), including the lead compound SS-31, offer promise, as they have been shown to restore healthy mitochondrial function and treat a variety of common diseases. At the cellular level, research has shown that MTPs accumulate strongly at the inner mitochondrial membrane (IMM), slow energy sinks (e.g., proton leaks), and improve ATP production. Modulation of electrostatic fields around the IMM has been implicated as a key aspect in the mechanism of action (MoA) of these peptides; however, molecular and mechanistic details have remained elusive. In this study, we employed all-atom molecular dynamics simulations (MD) to investigate the interactions of four MTPs with lipid bilayers and calculate their effect on structural and electrostatic properties. In agreement with previous experimental findings, we observed the modulation of the membrane surface and dipole potentials by MTPs. The simulations reveal that the MTPs achieve a reduction in the dipole potential by acting to disorder both lipid head groups and water layers proximal to the bilayer surface. We also find that MTPs decrease the bilayer thickness and increase the membrane's capacitance. These changes suggest that MTPs may enhance how much potential energy can be stored across the IMM at a given transmembrane potential difference. The MTPs also displace cations away from the bilayer surface, modulating the surface potential and offering an alternative mechanism for how these MTPs reduce mitochondrial energy sinks like proton leaks and mitigate Ca2+ accumulation stress. In conclusion, this study highlights the therapeutic potential of MTPs and underlines how interactions of MTPs with lipid bilayers serve as a fundamental component of their MoA.
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Affiliation(s)
- Jeffrey D Tamucci
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Nathan N Alder
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Eric R May
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269, United States
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3
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Muñoz-Rodríguez D, Bourqqia-Ramzi M, García-Esteban MT, Murciano-Cespedosa A, Vian A, Lombardo-Hernández J, García-Pérez P, Conejero F, Mateos González Á, Geuna S, Herrera-Rincon C. Bioelectrical State of Bacteria Is Linked to Growth Dynamics and Response to Neurotransmitters: Perspectives for the Investigation of the Microbiota-Brain Axis. Int J Mol Sci 2023; 24:13394. [PMID: 37686197 PMCID: PMC10488255 DOI: 10.3390/ijms241713394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 08/22/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023] Open
Abstract
Inter-cellular communication is mediated by a sum of biochemical, biophysical, and bioelectrical signals. This might occur not only between cells belonging to the same tissue and/or animal species but also between cells that are, from an evolutionary point of view, far away. The possibility that bioelectrical communication takes place between bacteria and nerve cells has opened exciting perspectives in the study of the gut microbiota-brain axis. The aim of this paper is (i) to establish a reliable method for the assessment of the bioelectrical state of two bacterial strains: Bacillus subtilis (B. subtilis) and Limosilactobacillus reuteri (L. reuteri); (ii) to monitor the bacterial bioelectrical profile throughout its growth dynamics; and (iii) to evaluate the effects of two neurotransmitters (glutamate and γ-aminobutyric acid-GABA) on the bioelectrical signature of bacteria. Our results show that membrane potential (Vmem) and the proliferative capacity of the population are functionally linked in B. subtilis in each phase of the cell cycle. Remarkably, we demonstrate that bacteria respond to neural signals by changing Vmem properties. Finally, we show that Vmem changes in response to neural stimuli are present also in a microbiota-related strain L. reuteri. Our proof-of-principle data reveal a new methodological approach for the better understanding of the relation between bacteria and the brain, with a special focus on gut microbiota. Likewise, this approach will open exciting perspectives in the study of the inter-cellular mechanisms which regulate the bi-directional communication between bacteria and neurons and, ultimately, for designing gut microbiota-brain axis-targeted treatments for neuropsychiatric diseases.
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Affiliation(s)
- David Muñoz-Rodríguez
- Biomathematics Unit, Data Analysis & Computational Tools for Biology Research Group, Department of Biodiversity, Ecology & Evolution, and Modeling, Complutense University of Madrid, 28040 Madrid, Spain
- Molecular Biotechnology Center, University of Turin, 10126 Turin, Italy
| | - Marwane Bourqqia-Ramzi
- Biomathematics Unit, Data Analysis & Computational Tools for Biology Research Group, Department of Biodiversity, Ecology & Evolution, and Modeling, Complutense University of Madrid, 28040 Madrid, Spain
- Molecular Biotechnology Center, University of Turin, 10126 Turin, Italy
| | - Maria Teresa García-Esteban
- Department of Genetics, Physiology and Microbiology, Complutense University of Madrid, 28040 Madrid, Spain (A.V.)
| | - Antonio Murciano-Cespedosa
- Biomathematics Unit, Data Analysis & Computational Tools for Biology Research Group, Department of Biodiversity, Ecology & Evolution, and Modeling, Complutense University of Madrid, 28040 Madrid, Spain
- Neuro-Computing and Neuro-Robotics Research Group, Neural Plasticity Research Group Instituto Investigación Sanitaria Hospital Clínico San Carlos (IdISSC), Complutense University of Madrid, 28040 Madrid, Spain
| | - Alejandro Vian
- Department of Genetics, Physiology and Microbiology, Complutense University of Madrid, 28040 Madrid, Spain (A.V.)
| | - Juan Lombardo-Hernández
- Biomathematics Unit, Data Analysis & Computational Tools for Biology Research Group, Department of Biodiversity, Ecology & Evolution, and Modeling, Complutense University of Madrid, 28040 Madrid, Spain
- Molecular Biotechnology Center, University of Turin, 10126 Turin, Italy
| | - Pablo García-Pérez
- Biomathematics Unit, Data Analysis & Computational Tools for Biology Research Group, Department of Biodiversity, Ecology & Evolution, and Modeling, Complutense University of Madrid, 28040 Madrid, Spain
| | - Francisco Conejero
- Biomathematics Unit, Data Analysis & Computational Tools for Biology Research Group, Department of Biodiversity, Ecology & Evolution, and Modeling, Complutense University of Madrid, 28040 Madrid, Spain
| | - Álvaro Mateos González
- NYU-ECNU Institute of Mathematical Sciences, Shanghai New York University, Shanghai 200122, China;
| | - Stefano Geuna
- Molecular Biotechnology Center, University of Turin, 10126 Turin, Italy
| | - Celia Herrera-Rincon
- Biomathematics Unit, Data Analysis & Computational Tools for Biology Research Group, Department of Biodiversity, Ecology & Evolution, and Modeling, Complutense University of Madrid, 28040 Madrid, Spain
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4
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de Souza‐Guerreiro TC, Bondelli G, Grobas I, Donini S, Sesti V, Bertarelli C, Lanzani G, Asally M, Paternò GM. Membrane Targeted Azobenzene Drives Optical Modulation of Bacterial Membrane Potential. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2205007. [PMID: 36710255 PMCID: PMC10015841 DOI: 10.1002/advs.202205007] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 01/17/2023] [Indexed: 05/29/2023]
Abstract
Recent studies have shown that bacterial membrane potential is dynamic and plays signaling roles. Yet, little is still known about the mechanisms of membrane potential dynamics regulation-owing to a scarcity of appropriate research tools. Optical modulation of bacterial membrane potential could fill this gap and provide a new approach for studying and controlling bacterial physiology and electrical signaling. Here, the authors show that a membrane-targeted azobenzene (Ziapin2) can be used to photo-modulate the membrane potential in cells of the Gram-positive bacterium Bacillus subtilis. It is found that upon exposure to blue-green light (λ = 470 nm), isomerization of Ziapin2 in the bacteria membrane induces hyperpolarization of the potential. To investigate the origin of this phenomenon, ion-channel-deletion strains and ion channel blockers are examined. The authors found that in presence of the chloride channel blocker idanyloxyacetic acid-94 (IAA-94) or in absence of KtrAB potassium transporter, the hyperpolarization response is attenuated. These results reveal that the Ziapin2 isomerization can induce ion channel opening in the bacterial membrane and suggest that Ziapin2 can be used for studying and controlling bacterial electrical signaling. This new optical tool could contribute to better understand various microbial phenomena, such as biofilm electric signaling and antimicrobial resistance.
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Affiliation(s)
| | - Gaia Bondelli
- Center for Nanoscience and TechnologyIstituto Italiano di TeconologiaMilano20133Italy
| | - Iago Grobas
- Physical and Theoretical Chemistry LaboratoryOxfordOX1 3QZUK
| | - Stefano Donini
- Center for Nanoscience and TechnologyIstituto Italiano di TeconologiaMilano20133Italy
| | - Valentina Sesti
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta” Politecnico di MilanoMilano20133Italy
| | - Chiara Bertarelli
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta” Politecnico di MilanoMilano20133Italy
| | - Guglielmo Lanzani
- Center for Nanoscience and TechnologyIstituto Italiano di TeconologiaMilano20133Italy
- Department of PhysicsPolitecnico di MilanoMilano20133Italy
| | - Munehiro Asally
- School of Life SciencesUniversity of WarwickCoventryCV4 7ALUK
| | - Giuseppe Maria Paternò
- Center for Nanoscience and TechnologyIstituto Italiano di TeconologiaMilano20133Italy
- Department of PhysicsPolitecnico di MilanoMilano20133Italy
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5
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Barbara R, Nagathihalli Kantharaju M, Haruvi R, Harrington K, Kawashima T. PyZebrascope: An Open-Source Platform for Brain-Wide Neural Activity Imaging in Zebrafish. Front Cell Dev Biol 2022; 10:875044. [PMID: 35663407 PMCID: PMC9161555 DOI: 10.3389/fcell.2022.875044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022] Open
Abstract
Understanding how neurons interact across the brain to control animal behaviors is one of the central goals in neuroscience. Recent developments in fluorescent microscopy and genetically-encoded calcium indicators led to the establishment of whole-brain imaging methods in zebrafish, which record neural activity across a brain-wide volume with single-cell resolution. Pioneering studies of whole-brain imaging used custom light-sheet microscopes, and their operation relied on commercially developed and maintained software not available globally. Hence it has been challenging to disseminate and develop the technology in the research community. Here, we present PyZebrascope, an open-source Python platform designed for neural activity imaging in zebrafish using light-sheet microscopy. PyZebrascope has intuitive user interfaces and supports essential features for whole-brain imaging, such as two orthogonal excitation beams and eye damage prevention. Its camera module can handle image data throughput of up to 800 MB/s from camera acquisition to file writing while maintaining stable CPU and memory usage. Its modular architecture allows the inclusion of advanced algorithms for microscope control and image processing. As a proof of concept, we implemented a novel automatic algorithm for maximizing the image resolution in the brain by precisely aligning the excitation beams to the image focal plane. PyZebrascope enables whole-brain neural activity imaging in fish behaving in a virtual reality environment. Thus, PyZebrascope will help disseminate and develop light-sheet microscopy techniques in the neuroscience community and advance our understanding of whole-brain neural dynamics during animal behaviors.
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Affiliation(s)
- Rani Barbara
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Madhu Nagathihalli Kantharaju
- Max-Delbrück-Centrum for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- Humboldt University of Berlin, Berlin, Germany
| | - Ravid Haruvi
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Kyle Harrington
- Max-Delbrück-Centrum for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- Oak Ridge National Laboratory, Oak Ridge, TN, United States
- *Correspondence: Kyle Harrington, ; Takashi Kawashima,
| | - Takashi Kawashima
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
- *Correspondence: Kyle Harrington, ; Takashi Kawashima,
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6
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Srinivasan P, Griffin NM, Thakur D, Joshi P, Nguyen-Le A, McCotter S, Jain A, Saeidi M, Kulkarni P, Eisdorfer JT, Rothman J, Montell C, Theogarajan L. An Autonomous Molecular Bioluminescent Reporter (AMBER) for Voltage Imaging in Freely Moving Animals. Adv Biol (Weinh) 2021; 5:e2100842. [PMID: 34761564 PMCID: PMC8858017 DOI: 10.1002/adbi.202100842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 10/08/2021] [Indexed: 11/12/2022]
Abstract
Genetically encoded reporters have greatly increased our understanding of biology. While fluorescent reporters have been widely used, photostability and phototoxicity have hindered their use in long-term experiments. Bioluminescence overcomes some of these challenges but requires the addition of an exogenous luciferin limiting its use. Using a modular approach, Autonomous Molecular BioluminEscent Reporter (AMBER), an indicator of membrane potential is engineered. Unlike other bioluminescent systems, AMBER is a voltage-gated luciferase coupling the functionalities of the Ciona voltage-sensing domain (VSD) and bacterial luciferase, luxAB. When co-expressed with the luciferin-producing genes, AMBER reversibly switches the bioluminescent intensity as a function of membrane potential. Using biophysical and biochemical methods, it is shown that AMBER switches its enzymatic activity from an OFF to an ON state as a function of the membrane potential. Upon depolarization, AMBER switches from a low to a high enzymatic activity state, showing a several-fold increase in the bioluminescence output (ΔL/L). AMBER in the pharyngeal muscles and mechanosensory touch neurons of Caenorhabditis elegans is expressed. Using the compressed sensing approach, the electropharingeogram of the C. elegans pharynx is reconstructed, validating the sensor in vivo. Thus, AMBER represents the first fully genetically encoded bioluminescent reporter without requiring exogenous luciferin addition.
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Affiliation(s)
- Prasanna Srinivasan
- Department of Electrical and Computer Engineering, University of California Santa Barbara, CA 93106
- Center for Bioengineering, Institute for Collaborative Biotechnologies, University of California Santa Barbara, CA 93106
| | - Nicole M Griffin
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA, 93106, USA
- Center for Bioengineering, Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA, 93106, USA
| | - Dhananjay Thakur
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, CA 93106
- The Neuroscience Research Institute, University of California Santa Barbara, CA 93106
| | - Pradeep Joshi
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, CA 93106
| | - Alex Nguyen-Le
- Department of Electrical and Computer Engineering, University of California Santa Barbara, CA 93106
- Current address: Department of Electrical Engineering, University of Pennsylvania, Philadelphia, PA
| | - Sean McCotter
- Department of Electrical and Computer Engineering, University of California Santa Barbara, CA 93106
| | - Akshar Jain
- Department of Electrical and Computer Engineering, University of California Santa Barbara, CA 93106
| | - Mitra Saeidi
- Department of Electrical and Computer Engineering, University of California Santa Barbara, CA 93106
| | - Prajakta Kulkarni
- Department of Electrical and Computer Engineering, University of California Santa Barbara, CA 93106
| | - Jaclyn T. Eisdorfer
- College of Creative Studies,University of California Santa Barbara, CA 93106 Current address: Dept. of Bioengineering, Temple University, Philadelphia, PA 19122
| | - Joel Rothman
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, CA 93106
| | - Craig Montell
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, CA 93106
- The Neuroscience Research Institute, University of California Santa Barbara, CA 93106
| | - Luke Theogarajan
- Department of Electrical and Computer Engineering, University of California Santa Barbara, CA 93106
- Center for Bioengineering, Institute for Collaborative Biotechnologies, University of California Santa Barbara, CA 93106
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7
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Paternò GM, Bondelli G, Lanzani G. Bringing Microbiology to Light: Toward All-Optical Electrophysiology in Bacteria. Bioelectricity 2021; 3:136-142. [PMID: 34476389 DOI: 10.1089/bioe.2021.0008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The observation of neuron-like behavior in bacteria, such as the occurrence of electric spiking and extended bioelectric signaling, points to the role of membrane dynamics in prokaryotes. Electrophysiology of bacteria, however, has been overlooked for long time, due to the difficulties in monitoring bacterial bioelectric phenomena with those probing techniques that are commonly used for eukaryotes. Optical technologies can allow a paradigm shift in the field of electrophysiology of bacteria, as they would permit to elicit and monitor signaling rapidly, remotely, and with high spatiotemporal precision. In this perspective, we discuss about the potentiality of light interrogation methods in microbiology, encouraging the development of all-optical electrophysiology of bacteria.
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Affiliation(s)
| | - Gaia Bondelli
- Center for Nanoscience and Technology, Istituto Italiano di Tecnologia, Milano, Italy.,Physics Department, Politecnico di Milano, Milano, Italy
| | - Guglielmo Lanzani
- Center for Nanoscience and Technology, Istituto Italiano di Tecnologia, Milano, Italy.,Physics Department, Politecnico di Milano, Milano, Italy
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8
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Limapichat W, Pornthanakasem W, Satitthammachart C, Chitnumsub P, Leartsakulpanich U. Real-time detection of changes in yeast plasma membrane potential using genetically encoded voltage indicator proteins. FEMS Yeast Res 2020; 20:5874255. [PMID: 32691845 DOI: 10.1093/femsyr/foaa041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 07/18/2020] [Indexed: 11/12/2022] Open
Abstract
In yeast, adaptation to varying conditions often requires proper regulation of the plasma membrane potential. To determine yeast membrane potential change, optical methods involving potentiometric dyes have been supplemental to the direct electrode-based method. However, the hydrophobic nature of the dyes and their slow distribution across the membrane still limits their utilization. Genetically encoded voltage indicator (GEVI) proteins employed in neuroscience offer a tantalizing alternative for monitoring yeast membrane potential change. In this work, several widely used GEVI proteins were assessed in Saccharomyces cerevisiae for their expression and function as a voltage reporter. Among them, only ArcLight and Accelerated Sensor of Action Potential (ASAP) proteins could be expressed and transported to the plasma membrane. While the voltage-sensing capability was demonstrated for both ArcLight and ASAP, ArcLight fluorescence was sensitive to the intracellular pH change concurrently with the voltage change. Therefore, we established that ASAP is the more suitable GEVI protein for reporting yeast membrane potential change. This voltage-sensing reporter for yeast based on ASAP offers a new effective strategy for real-time optical detection of yeast membrane potential change, which potentially facilitates many areas of yeast research including optimizing growth conditions for industrial use and investigating yeast ion transport system.
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Affiliation(s)
- Walrati Limapichat
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Wichai Pornthanakasem
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Chatchaya Satitthammachart
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Ubolsree Leartsakulpanich
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
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9
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Williamson G, Tamburrino G, Bizior A, Boeckstaens M, Dias Mirandela G, Bage MG, Pisliakov A, Ives CM, Terras E, Hoskisson PA, Marini AM, Zachariae U, Javelle A. A two-lane mechanism for selective biological ammonium transport. eLife 2020; 9:57183. [PMID: 32662768 PMCID: PMC7447429 DOI: 10.7554/elife.57183] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 07/13/2020] [Indexed: 11/13/2022] Open
Abstract
The transport of charged molecules across biological membranes faces the dual problem of accommodating charges in a highly hydrophobic environment while maintaining selective substrate translocation. This has been the subject of a particular controversy for the exchange of ammonium across cellular membranes, an essential process in all domains of life. Ammonium transport is mediated by the ubiquitous Amt/Mep/Rh transporters that includes the human Rhesus factors. Here, using a combination of electrophysiology, yeast functional complementation and extended molecular dynamics simulations, we reveal a unique two-lane pathway for electrogenic NH4+ transport in two archetypal members of the family, the transporters AmtB from Escherichia coli and Rh50 from Nitrosomonas europaea. The pathway underpins a mechanism by which charged H+ and neutral NH3 are carried separately across the membrane after NH4+ deprotonation. This mechanism defines a new principle of achieving transport selectivity against competing ions in a biological transport process.
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Affiliation(s)
- Gordon Williamson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Giulia Tamburrino
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Adriana Bizior
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Mélanie Boeckstaens
- Biology of Membrane Transport Laboratory, Department of Molecular Biology, Université Libre de Bruxelles, Gosselies, Belgium
| | - Gaëtan Dias Mirandela
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Marcus G Bage
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Andrei Pisliakov
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Callum M Ives
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Eilidh Terras
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Paul A Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Anna Maria Marini
- Biology of Membrane Transport Laboratory, Department of Molecular Biology, Université Libre de Bruxelles, Gosselies, Belgium
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Arnaud Javelle
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
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10
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K + and Ca 2+ Channels Regulate Ca 2+ Signaling in Chondrocytes: An Illustrated Review. Cells 2020; 9:cells9071577. [PMID: 32610485 PMCID: PMC7408816 DOI: 10.3390/cells9071577] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/23/2020] [Accepted: 06/25/2020] [Indexed: 12/16/2022] Open
Abstract
An improved understanding of fundamental physiological principles and progressive pathophysiological processes in human articular joints (e.g., shoulders, knees, elbows) requires detailed investigations of two principal cell types: synovial fibroblasts and chondrocytes. Our studies, done in the past 8–10 years, have used electrophysiological, Ca2+ imaging, single molecule monitoring, immunocytochemical, and molecular methods to investigate regulation of the resting membrane potential (ER) and intracellular Ca2+ levels in human chondrocytes maintained in 2-D culture. Insights from these published papers are as follows: (1) Chondrocyte preparations express a number of different ion channels that can regulate their ER. (2) Understanding the basis for ER requires knowledge of (a) the presence or absence of ligand (ATP/histamine) stimulation and (b) the extraordinary ionic composition and ionic strength of synovial fluid. (3) In our chondrocyte preparations, at least two types of Ca2+-activated K+ channels are expressed and can significantly hyperpolarize ER. (4) Accounting for changes in ER can provide insights into the functional roles of the ligand-dependent Ca2+ influx through store-operated Ca2+ channels. Some of the findings are illustrated in this review. Our summary diagram suggests that, in chondrocytes, the K+ and Ca2+ channels are linked in a positive feedback loop that can augment Ca2+ influx and therefore regulate lubricant and cytokine secretion and gene transcription.
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11
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Benarroch JM, Asally M. The Microbiologist’s Guide to Membrane Potential Dynamics. Trends Microbiol 2020; 28:304-314. [DOI: 10.1016/j.tim.2019.12.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/25/2019] [Accepted: 12/09/2019] [Indexed: 10/25/2022]
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12
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13
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Tsouka S, Hatzimanikatis V. redLips: a comprehensive mechanistic model of the lipid metabolic network of yeast. FEMS Yeast Res 2020; 20:5739921. [DOI: 10.1093/femsyr/foaa006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 02/17/2020] [Indexed: 12/12/2022] Open
Abstract
ABSTRACTOver the last decades, yeast has become a key model organism for the study of lipid biochemistry. Because the regulation of lipids has been closely linked to various physiopathologies, the study of these biomolecules could lead to new diagnostics and treatments. Before the field can reach this point, however, sufficient tools for integrating and analyzing the ever-growing availability of lipidomics data will need to be developed. To this end, genome-scale models (GEMs) of metabolic networks are useful tools, though their large size and complexity introduces too much uncertainty in the accuracy of predicted outcomes. Ideally, therefore, a model for studying lipids would contain only the pathways required for the proper analysis of these biomolecules, but would not be an ad hoc reduction. We hereby present a metabolic model that focuses on lipid metabolism constructed through the integration of detailed lipid pathways into an already existing GEM of Saccharomyces cerevisiae. Our model was then systematically reduced around the subsystems defined by these pathways to provide a more manageable model size for complex studies. We show that this model is as consistent and inclusive as other yeast GEMs regarding the focus and detail on the lipid metabolism, and can be used as a scaffold for integrating lipidomics data to improve predictions in studies of lipid-related biological functions.
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Affiliation(s)
- S Tsouka
- Laboratory of Computational Systems Biotechnology, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - V Hatzimanikatis
- Laboratory of Computational Systems Biotechnology, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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14
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Covalent Epitope Decoration of Carbon Electrodes using Solid Phase Peptide Synthesis. Sci Rep 2019; 9:17805. [PMID: 31780767 PMCID: PMC6882871 DOI: 10.1038/s41598-019-54000-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 11/06/2019] [Indexed: 11/08/2022] Open
Abstract
Long-term, minimally perturbative brain electrophysiology requires electrodes to seamlessly integrate into surrounding tissue. In this work, we demonstrate electrodes composed of covalently functionalized graphite, decorated with various functional affinity and epitope tags, and use them to detect changes in electrical potential on the surfaces of illuminated quantum dots and near fluorescing molecules. Affinity and epitope tagging of carbon was achieved using direct attachment of biotin and solid phase peptide synthesis (SPPS) of histidine (His)- and human influenza hemagglutinin (HA)-tags. Surface modification was confirmed with Auger, Energy-Dispersive X-ray (EDX), Raman, and fluorescence spectroscopy. Photoresponse was detected with compatible binding protein-surface tag combinations, confirming desired tag and electrode functionality. These results provide a path to organic, biofunctionalized, fully molecularly-defined electrodes for neuronal applications, and to a wide range of other secondary reactions and modifications of carbon; potential uses include affinity chromatography, DNA sequencing technologies, biomolecular sensors, and surfaces and scaffolds for targeted interfaces with biological tissues.
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15
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Toward Decoding Bioelectric Events in Xenopus Embryogenesis: New Methodology for Tracking Interplay Between Calcium and Resting Potentials In Vivo. J Mol Biol 2019; 432:605-620. [PMID: 31711960 DOI: 10.1016/j.jmb.2019.10.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 10/07/2019] [Accepted: 10/15/2019] [Indexed: 12/16/2022]
Abstract
Although chemical signaling during embryogenesis is readily addressed by a plethora of available techniques, the developmental functions of ionic signaling are still poorly understood. It is increasingly realized that bioelectric events in nonneural cells are critical for pattern regulation, but their study has been hampered by difficulties in monitoring and manipulating them in vivo. Recent developments in visualizing electrical signaling dynamics in the field of neuroscience have facilitated functional experiments that reveal instructive developmental bioelectric signals. However, there is a pressing need for additional tools to explore time-dependent ionic signaling to understand complex endogenous dynamics. Here, we present methodological advances, including 4D imaging and data analysis, for improved tracking of calcium flux in the Xenopus laevis embryo, lowering the barrier for in vivo physiology work in this important model system. Using these techniques, we investigated the relationship between bioelectric ion channel activity and calcium, finding that cell hyperpolarization and depolarization both induce persistent static elevation of cytoplasmic calcium levels that fade over developmental time. These calcium changes correlate with increased cell mobility in early embryos and abnormal craniofacial morphology in later embryos. We thus highlight membrane potential modulation as a tractable tool for modulation of signaling cascades that rely on calcium as a transduction mechanism. The methods we describe facilitate the study of important novel aspects of developmental physiology, are extendable to numerous classes of existing and forthcoming fluorescent physiological reporters, and establish highly accessible, inexpensive protocols for their investigation.
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16
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Tanaka A, Liu Z, Osakada Y. Synthesis of unsymmetric perylenediimide dye molecule and its photochemical properties on lipid membrane. Bioorg Med Chem Lett 2019; 29:1899-1903. [PMID: 31175011 DOI: 10.1016/j.bmcl.2019.05.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 05/17/2019] [Accepted: 05/27/2019] [Indexed: 10/26/2022]
Abstract
Optical manipulation of cellular function is one of the important targets in chemical biology and medicine. To achieve manipulation of cellular function using small molecules, photochemical reaction, such as photo-isomerization and photo-induced electron transfer, is one of the most promising reactions. Especially, photo-induced electron transfer process may be the crucial for their further development of photo-functional agents in living cells. However, such molecules, which enable the modification of cellular function, are limited and the further development is necessary. Herein, we synthesized a novel unsymmetric perylenediimide dye and investigated the cellular staining upon the addition in the cell culture medium. Furthermore, we observed the fluorescence quenching upon the addition of ascorbic acid as electron donor and report the preliminary results to manipulate Ca2+ concentration in living cell line upon 488-nm light photoirradiation.
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Affiliation(s)
- Atsushi Tanaka
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Zuoyue Liu
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Yasuko Osakada
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan; Institute for Advanced Co-Creation Studies, Osaka University, 1-1 Yamadagaoka, Suita, Osaka 565-0871, Japan.
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17
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Tuszynski J, Tilli TM, Levin M. Ion Channel and Neurotransmitter Modulators as Electroceutical Approaches to the Control of Cancer. Curr Pharm Des 2019; 23:4827-4841. [PMID: 28554310 PMCID: PMC6340161 DOI: 10.2174/1381612823666170530105837] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 05/17/2017] [Accepted: 05/23/2017] [Indexed: 11/22/2022]
Abstract
The activities of individual cells must be tightly coordinated in order to build and maintain complex 3-dimensional body structures during embryogenesis and regeneration. Thus, one way to view cancer is within systems biology as a network disorder affecting the ability of cells to properly interact with a morphodynamic field of instructive signals that keeps proliferation and migration orchestrated toward the anatomical needs of the host or-ganism. One layer of this set of instructive microenvironmental cues is bioelectrical. Voltage gradients among all somatic cells (not just excitable nerve and muscle) control cell behavior, and the ionic coupling of cells into networks via electrochemical synapses allows them to implement tissue-level patterning decisions. These gradients have been increasingly impli-cated in the induction and suppression of tumorigenesis and metastasis, in the emerging links between developmental bioelectricity to the cancer problem. Consistent with the well-known role of neurotransmitter molecules in transducing electrical activity to downstream cascades in the brain, serotonergic signaling has likewise been implicated in cancer. Here, we review these recent data and propose new approaches for manipulating bioelectric and neurotransmitter pathways in cancer biology based on a bioelectric view of cancer. To sup-port this methodology, we present new data on the effects of the SSRI Prozac and its analog (ZINC ID = ZINC06811610) on survival of both cancer (MCF7) and normal (MCF10A) breast cells exposed to these compounds. We found an IC50 concentration (25 μM for Pro-zac and 100 μM for the Prozac analog) at which these compounds inhibited tumor cell sur-vival and proliferation. Additionally, at these concentrations, we did not observe alterations in a non-tumoral cell line. This constitutes a proof-of-concept demonstration for our hy-pothesis that the use of both existing and novel drugs as electroceuticals could serve as an alternative to highly toxic chemotherapy strategies replacing or augmenting them with less toxic alternatives. We believe this new approach forms an exciting roadmap for future bio-medical advances.
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Affiliation(s)
- Jack Tuszynski
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta. Canada
| | - Tatiana M Tilli
- Laboratory of Biological System Modeling, National Institute for Science and Technology on Innovation in Neglected Diseases (INCT/IDN), Center for Technological Development in Health (CDTS), Oswaldo Cruz Foundation (Fiocruz), Rio de Janeiro. Brazil
| | - Michael Levin
- Biology Department, and Allen Discovery Center, Tufts University, Medford, MA, 02155. United States
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18
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Levin M. Guest Editorial. Bioelectricity 2019; 1:5-6. [PMID: 34471801 DOI: 10.1089/bioe.2019.29003.mll] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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19
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Matzke AJ, Lin WD, Matzke M. Evidence That Ion-Based Signaling Initiating at the Cell Surface Can Potentially Influence Chromatin Dynamics and Chromatin-Bound Proteins in the Nucleus. FRONTIERS IN PLANT SCIENCE 2019; 10:1267. [PMID: 31681370 PMCID: PMC6811650 DOI: 10.3389/fpls.2019.01267] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 09/11/2019] [Indexed: 05/18/2023]
Abstract
We have developed tools and performed pilot experiments to test the hypothesis that an intracellular ion-based signaling pathway, provoked by an extracellular stimulus acting at the cell surface, can influence interphase chromosome dynamics and chromatin-bound proteins in the nucleus. The experimental system employs chromosome-specific fluorescent tags and the genome-encoded fluorescent pH sensor SEpHluorinA227D, which has been targeted to various intracellular membranes and soluble compartments in root cells of Arabidopsis thaliana. We are using this system and three-dimensional live cell imaging to visualize whether fluorescent-tagged interphase chromosome sites undergo changes in constrained motion concurrently with reductions in membrane-associated pH elicited by extracellular ATP, which is known to trigger a cascade of events in plant cells including changes in calcium ion concentrations, pH, and membrane potential. To examine possible effects of the proposed ion-based signaling pathway directly at the chromatin level, we generated a pH-sensitive fluorescent DNA-binding protein that allows pH changes to be monitored at specific genomic sites. Results obtained using these tools support the existence of a rapid, ion-based signaling pathway that initiates at the cell surface and reaches the nucleus to induce alterations in interphase chromatin mobility and the surrounding pH of chromatin-bound proteins. Such a pathway could conceivably act under natural circumstances to allow external stimuli to swiftly influence gene expression by affecting interphase chromosome movement and the structures and/or activities of chromatin-associated proteins.
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Affiliation(s)
| | | | - Marjori Matzke
- *Correspondence: Antonius J.M. Matzke, ; Marjori Matzke,
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20
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Quach B, Krogh-Madsen T, Entcheva E, Christini DJ. Light-Activated Dynamic Clamp Using iPSC-Derived Cardiomyocytes. Biophys J 2018; 115:2206-2217. [PMID: 30447994 PMCID: PMC6289097 DOI: 10.1016/j.bpj.2018.10.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 08/23/2018] [Accepted: 10/02/2018] [Indexed: 01/31/2023] Open
Abstract
iPSC-derived cardiomyocytes (iPSC-CMs) are a potentially advantageous platform for drug screening because they provide a renewable source of human cardiomyocytes. One obstacle to their implementation is their immature electrophysiology, which reduces relevance to adult arrhythmogenesis. To address this, dynamic clamp is used to inject current representing the insufficient potassium current, IK1, thereby producing more adult-like electrophysiology. However, dynamic clamp requires patch clamp and is therefore low throughput and ill-suited for large-scale drug screening. Here, we use optogenetics to generate such a dynamic-clamp current. The optical dynamic clamp (ODC) uses outward-current-generating opsin, ArchT, to mimic IK1, resulting in more adult-like action potential morphology, similar to IK1 injection via classic dynamic clamp. Furthermore, in the presence of an IKr blocker, ODC revealed expected action potential prolongation and reduced spontaneous excitation. The ODC presented here still requires an electrode to measure Vm but provides a first step toward contactless dynamic clamp, which will not only enable high-throughput screening but may also allow control within multicellular iPSC-CM formats to better recapitulate adult in vivo physiology.
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Affiliation(s)
- Bonnie Quach
- Cardiovascular Research Institute, New York, New York; Weill Cornell Medicine, New York, New York
| | - Trine Krogh-Madsen
- Cardiovascular Research Institute, New York, New York; Weill Cornell Medicine, New York, New York
| | - Emilia Entcheva
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia
| | - David J Christini
- Cardiovascular Research Institute, New York, New York; Weill Cornell Medicine, New York, New York.
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21
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Maleckar MM, Clark RB, Votta B, Giles WR. The Resting Potential and K + Currents in Primary Human Articular Chondrocytes. Front Physiol 2018; 9:974. [PMID: 30233381 PMCID: PMC6131720 DOI: 10.3389/fphys.2018.00974] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 07/03/2018] [Indexed: 11/23/2022] Open
Abstract
Human transplant programs provide significant opportunities for detailed in vitro assessments of physiological properties of selected tissues and cell types. We present a semi-quantitative study of the fundamental electrophysiological/biophysical characteristics of human chondrocytes, focused on K+ transport mechanisms, and their ability to regulate to the resting membrane potential, Em. Patch clamp studies on these enzymatically isolated human chondrocytes reveal consistent expression of at least three functionally distinct K+ currents, as well as transient receptor potential (TRP) currents. The small size of these cells and their exceptionally low current densities present significant technical challenges for electrophysiological recordings. These limitations have been addressed by parallel development of a mathematical model of these K+ and TRP channel ion transfer mechanisms in an attempt to reveal their contributions to Em. In combination, these experimental results and simulations yield new insights into: (i) the ionic basis for Em and its expected range of values; (ii) modulation of Em by the unique articular joint extracellular milieu; (iii) some aspects of TRP channel mediated depolarization-secretion coupling; (iv) some of the essential biophysical principles that regulate K+ channel function in “chondrons.” The chondron denotes the chondrocyte and its immediate extracellular compartment. The presence of discrete localized surface charges and associated zeta potentials at the chondrocyte surface are regulated by cell metabolism and can modulate interactions of chondrocytes with the extracellular matrix. Semi-quantitative analysis of these factors in chondrocyte/chondron function may yield insights into progressive osteoarthritis.
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Affiliation(s)
- Mary M Maleckar
- Simula Research Laboratory, Center for Biomedical Computing and Center for Cardiological Innovation, Oslo, Norway.,Allen Institute for Cell Science, Seattle, WA, United States
| | - Robert B Clark
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | | | - Wayne R Giles
- Faculties of Kinesiology and Medicine, University of Calgary, Calgary, AB, Canada
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22
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Zonta F, Buratto D, Crispino G, Carrer A, Bruno F, Yang G, Mammano F, Pantano S. Cues to Opening Mechanisms From in Silico Electric Field Excitation of Cx26 Hemichannel and in Vitro Mutagenesis Studies in HeLa Transfectans. Front Mol Neurosci 2018; 11:170. [PMID: 29904340 PMCID: PMC5990870 DOI: 10.3389/fnmol.2018.00170] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 05/04/2018] [Indexed: 01/06/2023] Open
Abstract
Connexin channels play numerous essential roles in virtually every organ by mediating solute exchange between adjacent cells, or between cytoplasm and extracellular milieu. Our understanding of the structure-function relationship of connexin channels relies on X-ray crystallographic data for human connexin 26 (hCx26) intercellular gap junction channels. Comparison of experimental data and molecular dynamics simulations suggests that the published structures represent neither fully-open nor closed configurations. To facilitate the search for alternative stable configurations, we developed a coarse grained (CG) molecular model of the hCx26 hemichannel and studied its responses to external electric fields. When challenged by a field of 0.06 V/nm, the hemichannel relaxed toward a novel configuration characterized by a widened pore and an increased bending of the second transmembrane helix (TM2) at the level of the conserved Pro87. A point mutation that inhibited such transition in our simulations impeded hemichannel opening in electrophysiology and dye uptake experiments conducted on HeLa tranfectants. These results suggest that the hCx26 hemichannel uses a global degree of freedom to transit between different configuration states, which may be shared among the whole connexin family.
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Affiliation(s)
- Francesco Zonta
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy
| | - Damiano Buratto
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy
| | - Giulia Crispino
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy.,Venetian Institute of Molecular Medicine, Padua, Italy
| | - Andrea Carrer
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy.,Department of Biomedical Sciences, University of Padua, Padua, Italy
| | | | - Guang Yang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China
| | - Fabio Mammano
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.,CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy.,Venetian Institute of Molecular Medicine, Padua, Italy
| | - Sergio Pantano
- Group of Biomolecular Simulations, Institut Pasteur de Montevideo, Montevideo, Uruguay
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23
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Kiskinis E, Kralj JM, Zou P, Weinstein EN, Zhang H, Tsioras K, Wiskow O, Ortega JA, Eggan K, Cohen AE. All-Optical Electrophysiology for High-Throughput Functional Characterization of a Human iPSC-Derived Motor Neuron Model of ALS. Stem Cell Reports 2018; 10:1991-2004. [PMID: 29779896 PMCID: PMC5993648 DOI: 10.1016/j.stemcr.2018.04.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 04/20/2018] [Accepted: 04/22/2018] [Indexed: 11/26/2022] Open
Abstract
Human induced pluripotent stem cell (iPSC)-derived neurons are an attractive substrate for modeling disease, yet the heterogeneity of these cultures presents a challenge for functional characterization by manual patch-clamp electrophysiology. Here, we describe an optimized all-optical electrophysiology, “Optopatch,” pipeline for high-throughput functional characterization of human iPSC-derived neuronal cultures. We demonstrate the method in a human iPSC-derived motor neuron (iPSC-MN) model of amyotrophic lateral sclerosis (ALS). In a comparison of iPSC-MNs with an ALS-causing mutation (SOD1 A4V) with their genome-corrected controls, the mutants showed elevated spike rates under weak or no stimulus and greater likelihood of entering depolarization block under strong optogenetic stimulus. We compared these results with numerical simulations of simple conductance-based neuronal models and with literature results in this and other iPSC-based models of ALS. Our data and simulations suggest that deficits in slowly activating potassium channels may underlie the changes in electrophysiology in the SOD1 A4V mutation. All-optical electrophysiology enables high-throughput assays in hiPSC-derived neurons Neurons derived from ALS patients fire differently from genome-corrected controls A deficit in the Kv7 potassium current can explain the difference in firing
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Affiliation(s)
- Evangelos Kiskinis
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Joel M Kralj
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Peng Zou
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Eli N Weinstein
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Hongkang Zhang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Konstantinos Tsioras
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Ole Wiskow
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA
| | - J Alberto Ortega
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Kevin Eggan
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Adam E Cohen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Department of Physics, Harvard University, Cambridge, MA 02138, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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24
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Xu Y, Peng L, Wang S, Wang A, Ma R, Zhou Y, Yang J, Sun DE, Lin W, Chen X, Zou P. Hybrid Indicators for Fast and Sensitive Voltage Imaging. Angew Chem Int Ed Engl 2018; 57:3949-3953. [PMID: 29437274 DOI: 10.1002/anie.201712614] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 01/23/2018] [Indexed: 11/07/2022]
Abstract
Membrane voltage is an important biophysical signal that underlies intercellular electrical communications. A fluorescent voltage indicator is presented that enables the investigation of electrical signaling at high spatial resolution. The method is built upon the site-specific modification of microbial rhodopsin proteins with organic fluorophores, resulting in a hybrid indicator scaffold that is one of the most sensitive and fastest orange-colored voltage indicators developed to date. We applied this technique to optically map electrical connectivity in cultured cells, which revealed gap junction-mediated long-range coupling that spanned over hundreds of micrometers.
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Affiliation(s)
- Yongxian Xu
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China.,Peking-Tsinghua Center for Life Sciences, Beijing, 100871, China.,School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Luxin Peng
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Sicong Wang
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Anqi Wang
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China.,Peking-Tsinghua Center for Life Sciences, Beijing, 100871, China
| | - Ruirui Ma
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Ying Zhou
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Jiahe Yang
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China.,MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, Oxfordshire, OX3 9DS, UK
| | - De-En Sun
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Wei Lin
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China
| | - Xing Chen
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China.,Peking-Tsinghua Center for Life Sciences, Beijing, 100871, China
| | - Peng Zou
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, 100871, China.,Peking-Tsinghua Center for Life Sciences, Beijing, 100871, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, 100871, China
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25
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Xu Y, Peng L, Wang S, Wang A, Ma R, Zhou Y, Yang J, Sun DE, Lin W, Chen X, Zou P. Hybrid Indicators for Fast and Sensitive Voltage Imaging. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201712614] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Yongxian Xu
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
- Peking-Tsinghua Center for Life Sciences; Beijing 100871 China
- School of Life Sciences; Tsinghua University; Beijing 100084 China
| | - Luxin Peng
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
| | - Sicong Wang
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
| | - Anqi Wang
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
- Peking-Tsinghua Center for Life Sciences; Beijing 100871 China
| | - Ruirui Ma
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
| | - Ying Zhou
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
| | - Jiahe Yang
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
- MRC Human Immunology Unit; Weatherall Institute of Molecular Medicine; University of Oxford; Oxford Oxfordshire OX3 9DS UK
| | - De-en Sun
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
| | - Wei Lin
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
| | - Xing Chen
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
- Peking-Tsinghua Center for Life Sciences; Beijing 100871 China
| | - Peng Zou
- College of Chemistry and Molecular Engineering; Synthetic and Functional Biomolecules Center; Beijing National Laboratory for Molecular Sciences; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Peking University; Beijing 100871 China
- Peking-Tsinghua Center for Life Sciences; Beijing 100871 China
- PKU-IDG/McGovern Institute for Brain Research; Beijing 100871 China
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26
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Ni H, Narsingani K, Zhang H, Giles WR. Can principles of the surface potential be combined with knowledge of natural products to reduce atrial rhythm disturbances? Acta Physiol (Oxf) 2018; 222. [PMID: 28719150 DOI: 10.1111/apha.12918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- H. Ni
- Biological Physics Group; School of Physics & Astronomy; The University of Manchester; Manchester UK
| | - K. Narsingani
- Faculties of Kinesiology & Medicine; University of Calgary; Calgary AB Canada
| | - H. Zhang
- Biological Physics Group; School of Physics & Astronomy; The University of Manchester; Manchester UK
| | - W. R. Giles
- Faculties of Kinesiology & Medicine; University of Calgary; Calgary AB Canada
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27
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Abstract
Microbial rhodopsins (MRs) are a large family of photoactive membrane proteins, found in microorganisms belonging to all kingdoms of life, with new members being constantly discovered. Among the MRs are light-driven proton, cation and anion pumps, light-gated cation and anion channels, and various photoreceptors. Due to their abundance and amenability to studies, MRs served as model systems for a great variety of biophysical techniques, and recently found a great application as optogenetic tools. While the basic aspects of microbial rhodopsins functioning have been known for some time, there is still a plenty of unanswered questions. This chapter presents and summarizes the available knowledge, focusing on the functional and structural studies.
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Affiliation(s)
- Ivan Gushchin
- Moscow Institute of Physics and Technology, Dolgoprudniy, Russia.
| | - Valentin Gordeliy
- Moscow Institute of Physics and Technology, Dolgoprudniy, Russia.
- University of Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France.
- Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Jülich, Jülich, Germany.
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28
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Ma Y, Poole K, Goyette J, Gaus K. Introducing Membrane Charge and Membrane Potential to T Cell Signaling. Front Immunol 2017; 8:1513. [PMID: 29170669 PMCID: PMC5684113 DOI: 10.3389/fimmu.2017.01513] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 10/25/2017] [Indexed: 01/12/2023] Open
Abstract
While membrane models now include the heterogeneous distribution of lipids, the impact of membrane charges on regulating the association of proteins with the plasma membrane is often overlooked. Charged lipids are asymmetrically distributed between the two leaflets of the plasma membrane, resulting in the inner leaflet being negatively charged and a surface potential that attracts and binds positively charged ions, proteins, and peptide motifs. These interactions not only create a transmembrane potential but they can also facilitate the formation of charged membrane domains. Here, we reference fields outside of immunology in which consequences of membrane charge are better characterized to highlight important mechanisms. We then focus on T cell receptor (TCR) signaling, reviewing the evidence that membrane charges and membrane-associated calcium regulate phosphorylation of the TCR–CD3 complex and discuss how the immunological synapse exhibits distinct patterns of membrane charge distribution. We propose that charged lipids, ions in solution, and transient protein interactions form a dynamic equilibrium during T cell activation.
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Affiliation(s)
- Yuanqing Ma
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, NSW, Australia
| | - Kate Poole
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, NSW, Australia
| | - Jesse Goyette
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, NSW, Australia
| | - Katharina Gaus
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, NSW, Australia
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29
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Ferro M, Lamanna J, Ripamonti M, Racchetti G, Arena A, Spadini S, Montesano G, Cortese R, Zimarino V, Malgaroli A. Functional mapping of brain synapses by the enriching activity-marker SynaptoZip. Nat Commun 2017; 8:1229. [PMID: 29089485 PMCID: PMC5663910 DOI: 10.1038/s41467-017-01335-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 09/08/2017] [Indexed: 01/27/2023] Open
Abstract
Ideally, elucidating the role of specific brain circuits in animal behavior would require the ability to measure activity at all involved synapses, possibly with unrestricted field of view, thus even at those boutons deeply located into the brain. Here, we introduce and validate an efficient scheme reporting synaptic vesicle cycling in vivo. This is based on SynaptoZip, a genetically encoded molecule deploying in the vesicular lumen a bait moiety designed to capture upon exocytosis a labeled alien peptide, Synbond. The resulting signal is cumulative and stores the number of cycling events occurring at individual synapses. Since this functional signal is enduring and measurable both online and ex post, SynaptoZip provides a unique method for the analysis of the history of synaptic activity in regions several millimeters below the brain surface. We show its broad applicability by reporting stimulus-evoked and spontaneous circuit activity in wide cortical fields, in anesthetized and freely moving animals. Visualization of synaptic activity in the living brain is challenging. This study devises a simple and efficient scheme that reports synaptic vesicle recycling in vivo using SynaptoZip, a genetically encoded sensor of past synaptic activities.
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Affiliation(s)
- Mattia Ferro
- Università Vita-Salute San Raffaele, Milan, 20132, Italy.,Neurobiology of Learning Unit, Division of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, 20132, Italy
| | - Jacopo Lamanna
- Università Vita-Salute San Raffaele, Milan, 20132, Italy.,Neurobiology of Learning Unit, Division of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, 20132, Italy
| | - Maddalena Ripamonti
- Università Vita-Salute San Raffaele, Milan, 20132, Italy.,Neurobiology of Learning Unit, Division of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, 20132, Italy
| | - Gabriella Racchetti
- Università Vita-Salute San Raffaele, Milan, 20132, Italy.,Psychiatry and Clinical Psychobiology Unit, Division of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, 20132, Italy
| | - Alessandro Arena
- Università Vita-Salute San Raffaele, Milan, 20132, Italy.,Neurobiology of Learning Unit, Division of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, 20132, Italy.,Department of Physiology, Institute of Basal Medical Sciences, University of Oslo, Oslo, 0315, Norway
| | - Sara Spadini
- Università Vita-Salute San Raffaele, Milan, 20132, Italy.,Neurobiology of Learning Unit, Division of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, 20132, Italy
| | - Giovanni Montesano
- Università Vita-Salute San Raffaele, Milan, 20132, Italy.,Neurobiology of Learning Unit, Division of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, 20132, Italy.,Dipartimento Testa-Collo, San Paolo Hospital, University of Milan, Milan, 20122, Italy
| | | | - Vincenzo Zimarino
- Neurobiology of Learning Unit, Division of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, 20132, Italy
| | - Antonio Malgaroli
- Università Vita-Salute San Raffaele, Milan, 20132, Italy. .,Neurobiology of Learning Unit, Division of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, 20132, Italy.
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30
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Xu Y, Zou P, Cohen AE. Voltage imaging with genetically encoded indicators. Curr Opin Chem Biol 2017; 39:1-10. [PMID: 28460291 PMCID: PMC5581692 DOI: 10.1016/j.cbpa.2017.04.005] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 04/03/2017] [Accepted: 04/07/2017] [Indexed: 02/06/2023]
Abstract
Membrane voltages are ubiquitous throughout cell biology. Voltage is most commonly associated with excitable cells such as neurons and cardiomyocytes, although many other cell types and organelles also support electrical signaling. Voltage imaging in vivo would offer unique capabilities in reporting the spatial pattern and temporal dynamics of electrical signaling at the cellular and circuit levels. Voltage is not directly visible, and so a longstanding challenge has been to develop genetically encoded fluorescent voltage indicator proteins. Recent advances have led to a profusion of new voltage indicators, based on different scaffolds and with different tradeoffs between voltage sensitivity, speed, brightness, and spectrum. In this review, we describe recent advances in design and applications of genetically-encoded voltage indicators (GEVIs). We also highlight the protein engineering strategies employed to improve the dynamic range and kinetics of GEVIs and opportunities for future advances.
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Affiliation(s)
- Yongxian Xu
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Peng Zou
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China.
| | - Adam E Cohen
- Departments of Chemistry and Chemical Biology and of Physics, Harvard University, Cambridge, MA 02138, USA; Howard Hughes Medical Institute.
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31
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Zhang H, Cohen AE. Optogenetic Approaches to Drug Discovery in Neuroscience and Beyond. Trends Biotechnol 2017; 35:625-639. [PMID: 28552428 PMCID: PMC5495001 DOI: 10.1016/j.tibtech.2017.04.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 04/08/2017] [Accepted: 04/10/2017] [Indexed: 12/11/2022]
Abstract
Recent advances in optogenetics have opened new routes to drug discovery, particularly in neuroscience. Physiological cellular assays probe functional phenotypes that connect genomic data to patient health. Optogenetic tools, in particular tools for all-optical electrophysiology, now provide a means to probe cellular disease models with unprecedented throughput and information content. These techniques promise to identify functional phenotypes associated with disease states and to identify compounds that improve cellular function regardless of whether the compound acts directly on a target or through a bypass mechanism. This review discusses opportunities and unresolved challenges in applying optogenetic techniques throughout the discovery pipeline - from target identification and validation, to target-based and phenotypic screens, to clinical trials.
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Affiliation(s)
- Hongkang Zhang
- Department of Chemistry and Chemical Biology, Howard Hughes Medical Institute, Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Adam E Cohen
- Department of Chemistry and Chemical Biology, Howard Hughes Medical Institute, Department of Physics, Harvard University, Cambridge, MA 02138, USA.
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32
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Krah A, Zachariae U. Insights into the ion-coupling mechanism in the MATE transporter NorM-VC. Phys Biol 2017; 14:045009. [DOI: 10.1088/1478-3975/aa5ee7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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33
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Imaging electric field dynamics with graphene optoelectronics. Nat Commun 2016; 7:13704. [PMID: 27982125 PMCID: PMC5172231 DOI: 10.1038/ncomms13704] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 10/25/2016] [Indexed: 01/29/2023] Open
Abstract
The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts, a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena.
Detection of electric fields, central to chemical and biological processes, has been limited to measurements of current (e.g., electrodes) and secondary reporters (e.g., fluorescent dyes). Here, the authors demonstrate an optical platform capable of imaging electric field dynamics with high spatio-temporal resolution.
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34
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Brinks D, Adam Y, Kheifets S, Cohen AE. Painting with Rainbows: Patterning Light in Space, Time, and Wavelength for Multiphoton Optogenetic Sensing and Control. Acc Chem Res 2016; 49:2518-2526. [PMID: 27786461 DOI: 10.1021/acs.accounts.6b00415] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Photons are a fascinating reagent, flowing and reacting quite differently compared to more massive and less ephemeral particles of matter. The optogenetic palette comprises an ever growing set of light-responsive proteins, which open the possibility of using light to perturb and to measure biological processes with great precision in space and time. Yet there are limits on what light can achieve. Diffraction limits the smallest features, and scattering in tissue limits the largest. Photobleaching, diffusion of photogenerated products, and optical crosstalk between overlapping absorption spectra further muddy the optogenetic picture, particularly when one wants to use multiple optogenetic tools simultaneously. But these obstacles are surmountable. Most light-responsive proteins and small molecules undergo more than one light-driven transition, often with different action spectra and kinetics. By overlapping multiple laser beams, carefully patterned in space, time, and wavelength, one can steer molecules into fluorescent or nonfluorescent, active or inactive conformations. By doing so, one can often circumvent the limitations of simple one-photon excitation and achieve new imaging and stimulation capabilities. These include subdiffraction spatial resolution, optical sectioning, robustness to light scattering, and multiplexing of more channels than can be achieved with simple one-photon excitation. The microbial rhodopsins are a particularly rich substrate for this type of multiphoton optical control. The natural diversity of these proteins presents a huge range of starting materials. The spectroscopy and photocycles of microbial rhodopsins are relatively well understood, providing states with absorption maxima across the visible spectrum, which can be accessed on experimentally convenient time scales. A long history of mutational studies in microbial rhodopsins allows semirational protein engineering. Mutants of Archaerhodopsin 3 (Arch) come in all the colors of the rainbow. In a solution of purified Arch-eGFP, a focused green laser excites eGFP fluorescence throughout the laser path, while a focused red laser excites fluorescence of Arch only near the focus, indicative of multiphoton fluorescence. This nonlinearity occurs at a laser intensity ∼1010-fold lower than in conventional two-photon microscopy! The mutant Arch(D95H) shows photoswitchable optical bistability. In a lawn of E. coli expressing this mutant, illumination with patterned blue light converts the molecule into a state that is fluorescent. Illumination with red light excites this fluorescence, and gradually resets the molecules back to the non-fluorescent state. This review describes the new types of molecular logic that can be implemented with multi-photon control of microbial rhodopsins, from whole-brain activity mapping to measurements of absolute membrane voltage. Part of our goal in this Account is to describe recent work in nonlinear optogenetics, but we also present a variety of interesting things one could do if only the right optogenetic molecules were available. This latter component is intended to inspire future spectroscopic, protein discovery, and protein engineering work.
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Affiliation(s)
- Daan Brinks
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Yoav Adam
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Simon Kheifets
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Adam E. Cohen
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
- Department
of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- Howard
Hughes Medical Institute, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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35
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Matzke AJM, Matzke M. Expression and testing in plants of ArcLight, a genetically-encoded voltage indicator used in neuroscience research. BMC PLANT BIOLOGY 2015; 15:245. [PMID: 26459340 PMCID: PMC4603945 DOI: 10.1186/s12870-015-0633-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/30/2015] [Indexed: 05/28/2023]
Abstract
BACKGROUND It is increasingly appreciated that electrical controls acting at the cellular and supra-cellular levels influence development and initiate rapid responses to environmental cues. An emerging method for non-invasive optical imaging of electrical activity at cell membranes uses genetically-encoded voltage indicators (GEVIs). Developed by neuroscientists to chart neuronal circuits in animals, GEVIs comprise a fluorescent protein that is fused to a voltage-sensing domain. One well-known GEVI, ArcLight, undergoes strong shifts in fluorescence intensity in response to voltage changes in mammalian cells. ArcLight consists of super-ecliptic (SE) pHluorin (pH-sensitive fluorescent protein) with an A227D substitution, which confers voltage sensitivity in neurons, fused to the voltage-sensing domain of the voltage-sensing phosphatase of C iona i ntestinalis (Ci-VSD). In an ongoing effort to adapt tools of optical electrophysiology for plants, we describe here the expression and testing of ArcLight and various derivatives in different membranes of root cells in Arabidopsis thaliana. RESULTS Transgenic constructs were designed to express ArcLight and various derivatives targeted to the plasma membrane and nuclear membranes of Arabidopsis root cells. In transgenic seedlings, changes in fluorescence intensity of these reporter proteins following extracellular ATP (eATP) application were monitored using a fluorescence microscope equipped with a high speed camera. Coordinate reductions in fluorescence intensity of ArcLight and Ci-VSD-containing derivatives were observed at both the plasma membrane and nuclear membranes following eATP treatments. However, similar responses were observed for derivatives lacking the Ci-VSD. The dispensability of the Ci-VSD suggests that in plants, where H(+) ions contribute substantially to electrical activities, the voltage-sensing ability of ArcLight is subordinate to the pH sensitivity of its SEpHluorin base. The transient reduction of ArcLight fluorescence triggered by eATP most likely reflects changes in pH and not membrane voltage. CONCLUSIONS The pH sensitivity of ArcLight precludes its use as a direct sensor of membrane voltage in plants. Nevertheless, ArcLight and derivatives situated in the plasma membrane and nuclear membranes may offer robust, fluorescence intensity-based pH indicators for monitoring concurrent changes in pH at these discrete membrane systems. Such tools will assist analyses of pH as a signal and/or messenger at the cell surface and the nuclear periphery in living plants.
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Affiliation(s)
- Antonius J M Matzke
- Institute of Plant and Microbial Biology, Academia Sinica, 128, Section 2, Academia Road, Nangang District, Taipei 115, Taiwan.
| | - Marjori Matzke
- Institute of Plant and Microbial Biology, Academia Sinica, 128, Section 2, Academia Road, Nangang District, Taipei 115, Taiwan.
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36
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Venkatachalam V, Cohen AE. Imaging GFP-based reporters in neurons with multiwavelength optogenetic control. Biophys J 2015; 107:1554-63. [PMID: 25296307 DOI: 10.1016/j.bpj.2014.08.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 08/02/2014] [Accepted: 08/07/2014] [Indexed: 12/20/2022] Open
Abstract
To study the impact of neural activity on cellular physiology, one would like to combine precise control of firing patterns with highly sensitive probes of cellular physiology. Light-gated ion channels, e.g., Channelrhodopsin-2, enable precise control of firing patterns; green fluorescent protein-based reporters, e.g., the GCaMP6f Ca(2+) reporter, enable highly sensitive probing of cellular physiology. However, for most actuator-reporter combinations, spectral overlap prevents straightforward combination within a single cell. Here we explore multiwavelength control of channelrhodopsins to circumvent this limitation. The "stoplight" technique described in this article uses channelrhodopsin variants that are opened by blue light and closed by orange light. Cells are illuminated with constant blue light to excite fluorescence of a green fluorescent protein-based reporter. Modulated illumination with orange light negatively regulates activation of the channelrhodopsin. We performed detailed photophysical characterization and kinetic modeling of four candidate stoplight channelrhodopsins. The variant with the highest contrast, sdChR(C138S,E154A), enabled all-optical measurements of activity-induced calcium transients in cultured rat hippocampal neurons, although cell-to-cell variation in expression levels presents a challenge for quantification.
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Affiliation(s)
- Veena Venkatachalam
- Biophysics Program, Harvard Stem Cell Institute, Harvard University, Cambridge, Massachusetts
| | - Adam E Cohen
- Departments of Chemistry and Chemical Biology and Physics, Harvard Stem Cell Institute, Harvard University, Cambridge, Massachusetts; Howard Hughes Medical Institute, Chevy Chase, Maryland.
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37
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Spudich JL. Channelrhodopsin photochromic reactions provide multicolor optogenetic control. Biophys J 2014; 107:1489-90. [PMID: 25296299 DOI: 10.1016/j.bpj.2014.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 08/22/2014] [Indexed: 11/20/2022] Open
Affiliation(s)
- John L Spudich
- Center for Membrane Biology, Department of Biochemistry & Molecular Biology, University of Texas Medical School, Houston, Texas.
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38
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Hou JH, Kralj JM, Douglass AD, Engert F, Cohen AE. Simultaneous mapping of membrane voltage and calcium in zebrafish heart in vivo reveals chamber-specific developmental transitions in ionic currents. Front Physiol 2014; 5:344. [PMID: 25309445 PMCID: PMC4161048 DOI: 10.3389/fphys.2014.00344] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 08/22/2014] [Indexed: 01/31/2023] Open
Abstract
The cardiac action potential (AP) and the consequent cytosolic Ca2+ transient are key indicators of cardiac function. Natural developmental processes, as well as many drugs and pathologies change the waveform, propagation, or variability (between cells or over time) of these parameters. Here we apply a genetically encoded dual-function calcium and voltage reporter (CaViar) to study the development of the zebrafish heart in vivo between 1.5 and 4 days post fertilization (dpf). We developed a high-sensitivity spinning disk confocal microscope and associated software for simultaneous three-dimensional optical mapping of voltage and calcium. We produced a transgenic zebrafish line expressing CaViar under control of the heart-specific cmlc2 promoter, and applied ion channel blockers at a series of developmental stages to map the maturation of the action potential in vivo. Early in development, the AP initiated via a calcium current through L-type calcium channels. Between 90 and 102 h post fertilization (hpf), the ventricular AP switched to a sodium-driven upswing, while the atrial AP remained calcium driven. In the adult zebrafish heart, a sodium current drives the AP in both the atrium and ventricle. Simultaneous voltage and calcium imaging with genetically encoded reporters provides a new approach for monitoring cardiac development, and the effects of drugs on cardiac function.
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Affiliation(s)
- Jennifer H Hou
- Department of Physics, Harvard University Cambridge, MA, USA
| | - Joel M Kralj
- Department of Chemistry and Chemical Biology, Harvard University Cambridge, MA, USA
| | - Adam D Douglass
- Department of Molecular and Cellular Biology, Harvard University Cambridge, MA, USA
| | - Florian Engert
- Department of Molecular and Cellular Biology, Harvard University Cambridge, MA, USA
| | - Adam E Cohen
- Department of Physics, Harvard University Cambridge, MA, USA ; Department of Chemistry and Chemical Biology, Harvard University Cambridge, MA, USA ; Howard Hughes Medical Institute Chevy Chase, MD, USA
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39
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Zou P, Zhao Y, Douglass AD, Hochbaum DR, Brinks D, Werley CA, Harrison DJ, Campbell RE, Cohen AE. Bright and fast multicoloured voltage reporters via electrochromic FRET. Nat Commun 2014; 5:4625. [PMID: 25118186 PMCID: PMC4134104 DOI: 10.1038/ncomms5625] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 07/08/2014] [Indexed: 12/20/2022] Open
Abstract
Genetically encoded fluorescent reporters of membrane potential promise to reveal aspects of neural function not detectable by other means. We present a palette of multi-colored brightly fluorescent genetically encoded voltage indicators with sensitivities from 8 – 13% ΔF/F per 100 mV, and half-maximal response times from 4 – 7 ms. A fluorescent protein is fused to an Archaerhodopsin-derived voltage sensor. Voltage-induced shifts in the absorption spectrum of the rhodopsin lead to voltage-dependent nonradiative quenching of the appended fluorescent protein. Through a library screen, we identify linkers and fluorescent protein combinations which report neuronal action potentials in cultured rat hippocampal neurons with a single-trial signal-to-noise ratio from 7 to 9 in a 1 kHz imaging bandwidth at modest illumination intensity. The freedom to choose a voltage indicator from an array of colors facilitates multicolor voltage imaging, as well as combination with other optical reporters and optogenetic actuators.
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Affiliation(s)
- Peng Zou
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Yongxin Zhao
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - Adam D Douglass
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84132
| | - Daniel R Hochbaum
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Daan Brinks
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Christopher A Werley
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - D Jed Harrison
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - Robert E Campbell
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - Adam E Cohen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138.,Howard Hughes Medical Institute
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