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Forro C, Caron D, Angotzi GN, Gallo V, Berdondini L, Santoro F, Palazzolo G, Panuccio G. Electrophysiology Read-Out Tools for Brain-on-Chip Biotechnology. MICROMACHINES 2021; 12:124. [PMID: 33498905 PMCID: PMC7912435 DOI: 10.3390/mi12020124] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 02/07/2023]
Abstract
Brain-on-Chip (BoC) biotechnology is emerging as a promising tool for biomedical and pharmaceutical research applied to the neurosciences. At the convergence between lab-on-chip and cell biology, BoC couples in vitro three-dimensional brain-like systems to an engineered microfluidics platform designed to provide an in vivo-like extrinsic microenvironment with the aim of replicating tissue- or organ-level physiological functions. BoC therefore offers the advantage of an in vitro reproduction of brain structures that is more faithful to the native correlate than what is obtained with conventional cell culture techniques. As brain function ultimately results in the generation of electrical signals, electrophysiology techniques are paramount for studying brain activity in health and disease. However, as BoC is still in its infancy, the availability of combined BoC-electrophysiology platforms is still limited. Here, we summarize the available biological substrates for BoC, starting with a historical perspective. We then describe the available tools enabling BoC electrophysiology studies, detailing their fabrication process and technical features, along with their advantages and limitations. We discuss the current and future applications of BoC electrophysiology, also expanding to complementary approaches. We conclude with an evaluation of the potential translational applications and prospective technology developments.
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Affiliation(s)
- Csaba Forro
- Tissue Electronics, Fondazione Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci, 53-80125 Naples, Italy; (C.F.); (F.S.)
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Davide Caron
- Enhanced Regenerative Medicine, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (D.C.); (V.G.)
| | - Gian Nicola Angotzi
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (G.N.A.); (L.B.)
| | - Vincenzo Gallo
- Enhanced Regenerative Medicine, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (D.C.); (V.G.)
| | - Luca Berdondini
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (G.N.A.); (L.B.)
| | - Francesca Santoro
- Tissue Electronics, Fondazione Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci, 53-80125 Naples, Italy; (C.F.); (F.S.)
| | - Gemma Palazzolo
- Enhanced Regenerative Medicine, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (D.C.); (V.G.)
| | - Gabriella Panuccio
- Enhanced Regenerative Medicine, Fondazione Istituto Italiano di Tecnologia, Via Morego, 30-16163 Genova, Italy; (D.C.); (V.G.)
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Delaney SL, Gendreau JL, D'Souza M, Feng AY, Ho AL. Optogenetic Modulation for the Treatment of Traumatic Brain Injury. Stem Cells Dev 2020; 29:187-197. [DOI: 10.1089/scd.2019.0187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
| | | | | | - Austin Y. Feng
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, Georgia
| | - Allen L. Ho
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, Georgia
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3
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Two-Photon Excitation of Azobenzene Photoswitches for Synthetic Optogenetics. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10030805] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Synthetic optogenetics is an emerging optical technique that enables users to photocontrol molecules, proteins, and cells in vitro and in vivo. This is achieved by use of synthetic chromophores—denoted photoswitches—that undergo light-dependent changes (e.g., isomerization), which are meticulously designed to interact with unique cellular targets, notably proteins. Following light illumination, the changes adopted by photoswitches are harnessed to affect the function of nearby proteins. In most instances, photoswitches absorb visible light, wavelengths of poor tissue penetration, and excessive scatter. These shortcomings impede their use in vivo. To overcome these challenges, photoswitches of red-shifted absorbance have been developed. Notably, this shift in absorbance also increases their compatibility with two-photon excitation (2PE) methods. Here, we provide an overview of recent efforts devoted towards optimizing azobenzene-based photoswitches for 2PE and their current applications.
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Rustler K, Maleeva G, Bregestovski P, König B. Azologization of serotonin 5-HT 3 receptor antagonists. Beilstein J Org Chem 2019; 15:780-788. [PMID: 30992726 PMCID: PMC6444460 DOI: 10.3762/bjoc.15.74] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 03/14/2019] [Indexed: 01/05/2023] Open
Abstract
The serotonin 5-hydroxytryptamine 3 receptor (5-HT3R) plays a unique role within the seven classes of the serotonin receptor family, as it represents the only ionotropic receptor, while the other six members are G protein-coupled receptors (GPCRs). The 5-HT3 receptor is related to chemo-/radiotherapy provoked emesis and dysfunction leads to neurodevelopmental disorders and psychopathologies. Since the development of the first serotonin receptor antagonist in the early 1990s, the range of highly selective and potent drugs expanded based on various chemical structures. Nevertheless, on-off-targeting of a pharmacophore’s activity with high spatiotemporal resolution as provided by photopharmacology remains an unsolved challenge bearing additionally the opportunity for detailed receptor examination. In the presented work, we summarize the synthesis, photochromic properties and in vitro characterization of azobenzene-based photochromic derivatives of published 5-HT3R antagonists. Despite reported proof of principle of direct azologization, only one of the investigated derivatives showed antagonistic activity lacking isomer specificity.
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Affiliation(s)
- Karin Rustler
- Institute of Organic Chemistry, University of Regensburg, 93053 Regensburg, Germany
| | - Galyna Maleeva
- Aix-Marseille University, INSERM, INS, Institut de Neurosciences des Systèmes, 13005 Marseille, France
| | - Piotr Bregestovski
- Aix-Marseille University, INSERM, INS, Institut de Neurosciences des Systèmes, 13005 Marseille, France.,Department of Normal Physiology, Kazan State Medical University, Kazan, Russia.,Institute of Neurosciences, Kazan State Medical University, Kazan, Russia
| | - Burkhard König
- Institute of Organic Chemistry, University of Regensburg, 93053 Regensburg, Germany
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Carmi I, De Battista M, Maddalena L, Carroll EC, Kienzler MA, Berlin S. Holographic two-photon activation for synthetic optogenetics. Nat Protoc 2019; 14:864-900. [PMID: 30804570 DOI: 10.1038/s41596-018-0118-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 12/17/2018] [Indexed: 12/25/2022]
Abstract
Optogenetic tools provide users the ability to photocontrol the activity of cells. Commonly, activation is achieved by expression of proteins from photosynthetic organisms, for example, microbial opsins (e.g., ChR2). Alternatively, a sister approach, synthetic optogenetics, enables photocontrol over proteins of mammalian origin by use of photoswitches, visible light (typically), and genetic modification. Thus, synthetic optogenetics facilitates interrogation of native neuronal signaling mechanisms. However, the poor tissue penetration of visible wavelengths impedes the use of the technique in tissue, as two-photon excitation (2PE) is typically required to access the near-infrared window. Here, we describe an alternative technique that uses 2PE-compatible photoswitches (section 1) for photoactivation of genetically modified glutamate receptors (section 2). Furthermore, for fast, multi-region photoactivation, we describe the use of 2P-digital holography (2P-DH) (section 3). We detail how to combine 2P-DH and synthetic optogenetics with electrophysiology, or with red fluorescence Ca2+ recordings, for all-optical neural interrogation. The time required to complete the methods, aside from obtaining the necessary reagents and illumination equipment, is ~3 weeks.
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Affiliation(s)
- Ido Carmi
- Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Marco De Battista
- Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Laura Maddalena
- Department of Imaging Physics, Delft University of Technology, Delft, the Netherlands
| | - Elizabeth C Carroll
- Department of Imaging Physics, Delft University of Technology, Delft, the Netherlands
| | | | - Shai Berlin
- Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
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Rustler K, Pockes S, König B. Light-Switchable Antagonists for the Histamine H 1 Receptor at the Isolated Guinea Pig Ileum. ChemMedChem 2019; 14:636-644. [PMID: 30628180 DOI: 10.1002/cmdc.201800815] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Indexed: 12/13/2022]
Abstract
The histamine H1 G protein-coupled receptor (GPCR) plays an important role in allergy and inflammation. Existing drugs that address the H1 receptor differ in their chemical structure, pharmacology, and side effects. Light-controllable spatial and temporal activity regulation of photochromic H1 ligands may contribute to a better mechanistic understanding and the development of improved correlations between ligand structure and pharmacologic effects. We report photochromic H1 receptor ligands, which were investigated in an organ-pharmacological assay. Initially, five photochromic azobenzene derivatives of reported dual H1 -H4 receptor antagonists were designed, synthesized, photochemically characterized, and organ-pharmacologically tested on the isolated guinea pig ileum. Among them, one compound [trans-19: (Z)-1-(4-chlorophenyl)-1-(4-methylpiperazin-1-yl)-N-(4-((E)-phenyldiazenyl)phenyl)methanimine] retained the antagonistic activity of its non-photochromic lead, and trans-cis isomerization by irradiation induced a fourfold difference in the pharmacological response. Further structural optimization resulted in two bathochromically shifted derivatives of 19 [NO2 -substituted 35 {(Z)-1-(4-chlorophenyl)-1-(4-methylpiperazin-1-yl)-N-(4-((E)-(4-nitrophenyl)diazenyl)phenyl)methanimine} and SO3 - -substituted 41 {4-((E)-(4-(((Z)-(4-chlorophenyl)(4-methylpiperazin-1-yl)methylene)amino)phenyl)diazenyl)benzenesulfonate}], which do not require the use of UV light for photoisomerization and which also have improved solubility and show reduced tissue impairment. The trans isomers of both compounds showed a remarkable increase in antagonistic activity relative to their lead trans-19; furthermore, a 46-fold difference in activity on the isolated guinea pig ileum was observed between trans- and cis-35.
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Affiliation(s)
- Karin Rustler
- Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Steffen Pockes
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Burkhard König
- Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
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Ankenbruck N, Courtney T, Naro Y, Deiters A. Optochemical Control of Biological Processes in Cells and Animals. Angew Chem Int Ed Engl 2018; 57:2768-2798. [PMID: 28521066 PMCID: PMC6026863 DOI: 10.1002/anie.201700171] [Citation(s) in RCA: 292] [Impact Index Per Article: 48.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 05/06/2017] [Indexed: 12/13/2022]
Abstract
Biological processes are naturally regulated with high spatial and temporal control, as is perhaps most evident in metazoan embryogenesis. Chemical tools have been extensively utilized in cell and developmental biology to investigate cellular processes, and conditional control methods have expanded applications of these technologies toward resolving complex biological questions. Light represents an excellent external trigger since it can be controlled with very high spatial and temporal precision. To this end, several optically regulated tools have been developed and applied to living systems. In this review we discuss recent developments of optochemical tools, including small molecules, peptides, proteins, and nucleic acids that can be irreversibly or reversibly controlled through light irradiation, with a focus on applications in cells and animals.
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Affiliation(s)
- Nicholas Ankenbruck
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA
| | - Taylor Courtney
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA
| | - Yuta Naro
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA
| | - Alexander Deiters
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA
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Ankenbruck N, Courtney T, Naro Y, Deiters A. Optochemische Steuerung biologischer Vorgänge in Zellen und Tieren. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201700171] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Nicholas Ankenbruck
- Department of Chemistry University of Pittsburgh Pittsburgh Pennsylvania 15260 USA
| | - Taylor Courtney
- Department of Chemistry University of Pittsburgh Pittsburgh Pennsylvania 15260 USA
| | - Yuta Naro
- Department of Chemistry University of Pittsburgh Pittsburgh Pennsylvania 15260 USA
| | - Alexander Deiters
- Department of Chemistry University of Pittsburgh Pittsburgh Pennsylvania 15260 USA
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Berlin S, Isacoff EY. Synapses in the spotlight with synthetic optogenetics. EMBO Rep 2017; 18:677-692. [PMID: 28396573 DOI: 10.15252/embr.201744010] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/02/2017] [Accepted: 03/09/2017] [Indexed: 12/15/2022] Open
Abstract
Membrane receptors and ion channels respond to various stimuli and relay that information across the plasma membrane by triggering specific and timed processes. These include activation of second messengers, allowing ion permeation, and changing cellular excitability, to name a few. Gaining control over equivalent processes is essential to understand neuronal physiology and pathophysiology. Recently, new optical techniques have emerged proffering new remote means to control various functions of defined neuronal populations by light, dubbed optogenetics. Still, optogenetic tools do not typically address the activity of receptors and channels native to neurons (or of neuronal origin), nor gain access to their signaling mechanisms. A related method-synthetic optogenetics-bridges this gap by endowing light sensitivity to endogenous neuronal receptors and channels by the appending of synthetic, light-receptive molecules, or photoswitches. This provides the means to photoregulate neuronal receptors and channels and tap into their native signaling mechanisms in select regions of the neurons, such as the synapse. This review discusses the development of synthetic optogenetics as a means to study neuronal receptors and channels remotely, in their natural environment, with unprecedented spatial and temporal precision, and provides an overview of tool design, mode of action, potential clinical applications and insights and achievements gained.
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Affiliation(s)
- Shai Berlin
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa, Israel
| | - Ehud Y Isacoff
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.,Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.,Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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Schöneberg T, Kleinau G, Brüser A. What are they waiting for?—Tethered agonism in G protein-coupled receptors. Pharmacol Res 2016; 108:9-15. [DOI: 10.1016/j.phrs.2016.03.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 03/24/2016] [Indexed: 01/02/2023]
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Pendharkar AV, Levy SL, Ho AL, Sussman ES, Cheng MY, Steinberg GK. Optogenetic modulation in stroke recovery. Neurosurg Focus 2016; 40:E6. [DOI: 10.3171/2016.2.focus163] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Stroke is one of the leading contributors to morbidity, mortality, and health care costs in the United States. Although several preclinical strategies have shown promise in the laboratory, few have succeeded in the clinical setting. Optogenetics represents a promising molecular tool, which enables highly specific circuit-level neuromodulation. Here, the conceptual background and preclinical body of evidence for optogenetics are reviewed, and translational considerations in stroke recovery are discussed.
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12
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Levitz J, Popescu AT, Reiner A, Isacoff EY. A Toolkit for Orthogonal and in vivo Optical Manipulation of Ionotropic Glutamate Receptors. Front Mol Neurosci 2016; 9:2. [PMID: 26869877 PMCID: PMC4735401 DOI: 10.3389/fnmol.2016.00002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 01/06/2016] [Indexed: 12/16/2022] Open
Abstract
The ability to optically manipulate specific neuronal signaling proteins with genetic precision paves the way for the dissection of their roles in brain function, behavior, and disease. Chemical optogenetic control with photoswitchable tethered ligands (PTLs) enables rapid, reversible and reproducible activation or block of specific neurotransmitter-gated receptors and ion channels in specific cells. In this study, we further engineered and characterized the light-activated GluK2 kainate receptor, LiGluR, to develop a toolbox of LiGluR variants. Low-affinity LiGluRs allow for efficient optical control of GluK2 while removing activation by native glutamate, whereas variant RNA edited versions enable the synaptic role of receptors with high and low Ca2+ permeability to be assessed and spectral variant photoswitches provide flexibility in illumination. Importantly, we establish that LiGluR works efficiently in the cortex of awake, adult mice using standard optogenetic techniques, thus opening the door to probing the role of specific synaptic receptors and cellular signals in the neural circuit operations of the mammalian brain in normal conditions and in disease. The principals developed in this study are widely relevant to the engineering and in vivo use of optically controllable proteins, including other neurotransmitter receptors.
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Affiliation(s)
- Joshua Levitz
- Department of Molecular and Cell Biology, University of California, Berkeley Berkeley, CA, USA
| | - Andrei T Popescu
- Department of Molecular and Cell Biology, University of California, Berkeley Berkeley, CA, USA
| | - Andreas Reiner
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeley, CA, USA; Department of Biology and Biotechnology, Ruhr-University BochumBochum, Germany
| | - Ehud Y Isacoff
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeley, CA, USA; Helen Wills Neuroscience Institute, University of California, BerkeleyBerkeley, CA, USA; Physical Bioscience Division, Lawrence Berkeley National LaboratoryBerkeley, CA, USA
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Abstract
Synthetic biology (SB) is an emerging discipline, which is slowly reorienting the field of drug discovery. For thousands of years, living organisms such as plants were the major source of human medicines. The difficulty in resynthesizing natural products, however, often turned pharmaceutical industries away from this rich source for human medicine. More recently, progress on transformation through genetic manipulation of biosynthetic units in microorganisms has opened the possibility of in-depth exploration of the large chemical space of natural products derivatives. Success of SB in drug synthesis culminated with the bioproduction of artemisinin by microorganisms, a tour de force in protein and metabolic engineering. Today, synthetic cells are not only used as biofactories but also used as cell-based screening platforms for both target-based and phenotypic-based approaches. Engineered genetic circuits in synthetic cells are also used to decipher disease mechanisms or drug mechanism of actions and to study cell-cell communication within bacteria consortia. This review presents latest developments of SB in the field of drug discovery, including some challenging issues such as drug resistance and drug toxicity.
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Affiliation(s)
| | - Pablo Carbonell
- Faculty of Life Sciences, SYNBIOCHEM Centre, Manchester Institute of Biotechnology, University of Manchester, Manchester, UK
- Department of Experimental and Health Sciences (DCEXS), Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM), Universitat Pompeu Fabra (UPF), Barcelona, Spain
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Controlling ionotropic and metabotropic glutamate receptors with light: principles and potential. Curr Opin Pharmacol 2015; 20:135-43. [PMID: 25573450 DOI: 10.1016/j.coph.2014.12.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 12/08/2014] [Accepted: 12/08/2014] [Indexed: 01/24/2023]
Abstract
Light offers unique advantages for studying and manipulating biomolecules and the cellular processes that they control. Optical control of ionotropic and metabotropic glutamate receptors has garnered significant interest, since these receptors are central to signaling at neuronal synapses and only optical approaches provide the spatial and temporal resolution required to directly probe receptor function in cells and tissue. Following the classical method of glutamate photo-uncaging, recently developed methods have added other forms of remote control, including those with high molecular specificity and genetic targeting. These tools open the door to the direct optical control of synaptic transmission and plasticity, as well as the probing of native receptor function in intact neural circuits.
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Restoration of visual function by expression of a light-gated mammalian ion channel in retinal ganglion cells or ON-bipolar cells. Proc Natl Acad Sci U S A 2014; 111:E5574-83. [PMID: 25489083 DOI: 10.1073/pnas.1414162111] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Most inherited forms of blindness are caused by mutations that lead to photoreceptor cell death but spare second- and third-order retinal neurons. Expression of the light-gated excitatory mammalian ion channel light-gated ionotropic glutamate receptor (LiGluR) in retinal ganglion cells (RGCs) of the retina degeneration (rd1) mouse model of blindness was previously shown to restore some visual functions when stimulated by UV light. Here, we report restored retinal function in visible light in rodent and canine models of blindness through the use of a second-generation photoswitch for LiGluR, maleimide-azobenzene-glutamate 0 with peak efficiency at 460 nm (MAG0(460)). In the blind rd1 mouse, multielectrode array recordings of retinal explants revealed robust and uniform light-evoked firing when LiGluR-MAG0(460) was targeted to RGCs and robust but diverse activity patterns in RGCs when LiGluR-MAG0(460) was targeted to ON-bipolar cells (ON-BCs). LiGluR-MAG0(460) in either RGCs or ON-BCs of the rd1 mouse reinstated innate light-avoidance behavior and enabled mice to distinguish between different temporal patterns of light in an associative learning task. In the rod-cone dystrophy dog model of blindness, LiGluR-MAG0(460) in RGCs restored robust light responses to retinal explants and intravitreal delivery of LiGluR and MAG0(460) was well tolerated in vivo. The results in both large and small animal models of photoreceptor degeneration provide a path to clinical translation.
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