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Ellis-Davies GCR. Reverse Engineering Caged Compounds: Design Principles for their Application in Biology. Angew Chem Int Ed Engl 2023; 62:e202206083. [PMID: 36646644 PMCID: PMC10015297 DOI: 10.1002/anie.202206083] [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: 04/26/2022] [Indexed: 01/18/2023]
Abstract
Light passes through biological tissue, and so it is used for imaging biological processes in situ. Such observation is part of the very essence of science, but mechanistic understanding requires intervention. For more than 50 years a "second function" for light has emerged; namely, that of photochemical control. Caged compounds are biologically inert signaling molecules that are activated by light. These optical probes enable external instruction of biological processes by stimulation of an individual element in complex signaling cascades in its native environment. Cause and effect are linked directly in spatial, temporal, and frequency domains in a quantitative manner by their use. I provide a guide to the basic properties required to make effective caged compounds for the biological sciences.
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Affiliation(s)
- Graham C R Ellis-Davies
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, (Previously, Mount Sinai School of Medicine), 10029, New York, NY, USA
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2
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Ellis‐Davies GCR. Reverse Engineering Caged Compounds: Design Principles for their Application in Biology. Angew Chem Int Ed Engl 2023. [DOI: 10.1002/ange.202206083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Graham C. R. Ellis‐Davies
- Department of Neuroscience Icahn School of Medicine at Mount Sinai (Previously, Mount Sinai School of Medicine) 10029 New York NY USA
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Synthesis and Photolytic Assessment of Nitroindolinyl-Caged Calcium Ion Chelators. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27092645. [PMID: 35565996 PMCID: PMC9104977 DOI: 10.3390/molecules27092645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/15/2022] [Accepted: 04/18/2022] [Indexed: 11/17/2022]
Abstract
Neuroactive amino acids derivatised at their carboxylate groups with a photolabile nitroindolinyl group are highly effective reagents for the sub-µs release of neuroactive amino acids in physiological solutions. However, the same does not apply in the case of calcium ion chelators. In this study, nitroindolinyl-caged BAPTA is found to be completely photostable, whereas nitroindolinyl-caged EDTA photolyses only when saturated with calcium ions.
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Agarwal HK, Janicek R, Zhao J, Sambath K, Egger M, Niggli E, Ellis-Davies GCR. The yin and yang of intracellular delivery of amphipathic optical probes using n-butyl charge masking. Chem Commun (Camb) 2022; 58:2826-2829. [PMID: 35112125 PMCID: PMC9502023 DOI: 10.1039/d1cc06792c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Monitoring and manipulation of ionized intracellular calcium concentrations within intact, living cells using optical probes with organic chromophores is a core method for cell physiology. Since all these probes have multiple negative charges, they must be smuggled through the plasma membrane in a transiently neutral form, with intracellular esterases used to deprotect the masked anions. Here we explore the ability of the synthetically easily accessible n-butyl ester protecting group to deliver amphipathic cargoes to the cytosol. We show that the size of the caging chromophore conditions the ability of intracellular probe delivery and esterase charge unmasking.
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Affiliation(s)
- Hitesh K. Agarwal
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY 10029, USA.,School of Pharmacy, South University, Savannah, GA 31406, USA
| | | | - Jun Zhao
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY 10029, USA.
| | - Karthik Sambath
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY 10029, USA.
| | - Marcel Egger
- Department of Physiology, University of Bern, Bern, Switzerland
| | - Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland
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Pham TTT, Jakkampudi S, Furukawa K, Cheng FY, Lin TC, Nakamura Y, Morioka N, Abe M. p-Nitroterphenyl units for near-infrared two-photon uncaging of calcium ions. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2021.113154] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Abstract
Glutamate is the major excitatory neurotransmitter in the brain, and photochemical release of glutamate (or uncaging) is a chemical technique widely used by biologists to interrogate its physiology. A basic prerequisite of these optical probes is bio-inertness before photolysis. However, all caged glutamates are known to have strong antagonism toward receptors of γ-aminobutyric acid, the major inhibitory transmitter. We have developed a caged glutamate probe that is inert toward these receptors at concentrations that are effective for photolysis with violet light. Pharmacological tests in vitro revealed that attachment of a fifth-generation (G5) dendrimer (i.e., cloaking) to the widely used 4-methoxy-7-nitro-indolinyl(MNI)-Glu probe prevented such off-target effects while not changing the photochemical properties of MNI-Glu significantly. G5-MNI-Glu was used with optofluidic delivery to stimulate dopamine neurons of the ventral tegmental area of freely moving mice in a conditioned place-preference protocol so as to mediate Pavlovian conditioning.
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Vorobev AY, Moskalensky AE. Long-wavelength photoremovable protecting groups: On the way to in vivo application. Comput Struct Biotechnol J 2019; 18:27-34. [PMID: 31890141 PMCID: PMC6920508 DOI: 10.1016/j.csbj.2019.11.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 01/07/2023] Open
Abstract
Photoremovable protective groups (PPGs) and related "caged" compounds have been recognized as a powerful tool in an arsenal of life science methods. The present review is focused on recent advances in design of "caged" compounds which function in red or near-infrared region. The naive comparison of photon energy with that of organic bond leads to the illusion that long-wavelength activation is possible only for weak chemical bonds like N-N. However, there are different means to overcome this threshold and shift the uncaging functionality into red or near-infrared regions for general organic bonds. We overview these strategies, including the novel photochemical and photophysical mechanisms used in newly developed PPGs, singlet-oxygen-mediated photolysis, and two-photon absorption. Recent advances in science places the infrared-sensitive PPGs to the same usability level as traditional ones, facilitating in vivo application of caged compounds.
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Affiliation(s)
- Aleksey Yu. Vorobev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, 9 Lavrentiev Ave., Novosibirsk 630090, Russia
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Alexander E. Moskalensky
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
- Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, Institutskaya str. 3, Novosibirsk 630090, Russia
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Passlick S, Thapaliya ER, Chen Z, Richers MT, Ellis-Davies GCR. Optical probing of acetylcholine receptors on neurons in the medial habenula with a novel caged nicotine drug analogue. J Physiol 2018; 596:5307-5318. [PMID: 30222192 DOI: 10.1113/jp276615] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/13/2018] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS A new caged nicotinic acetylcholine receptor (nAChR) agonist was developed, ABT594, which is photolysed by one- and two-photon excitation. The caged compound is photolysed with a quantum yield of 0.20. One-photon uncaging of ABT594 elicited large currents and Ca2+ transients at the soma and dendrites of medial habenula (MHb) neurons of mouse brain slices. Unexpectedly, uncaging of ABT594 also revealed highly Ca2+ -permeable nAChRs on axons of MHb neurons. ABSTRACT Photochemical release of neurotransmitters has been instrumental in the study of their underlying receptors, with acetylcholine being the exception due to its inaccessibility to photochemical protection. We caged a nicotinic acetylcholine receptor (nAChR) agonist, ABT594, via its secondary amine functionality. Effective photolysis could be carried out using either one- or two-photon excitation. Brief flashes (0.5-3.0 ms) of 410 nm light evoked large currents and Ca2+ transients on cell bodies and dendrites of medial habenula (MHb) neurons. Unexpectedly, photorelease of ABT594 also revealed nAChR-mediated Ca2+ signals along the axons of MHb neurons.
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Affiliation(s)
- Stefan Passlick
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
| | - Ek Raj Thapaliya
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
| | - Zuxin Chen
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
| | - Matthew T Richers
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
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Font J, López-Cano M, Notartomaso S, Scarselli P, Di Pietro P, Bresolí-Obach R, Battaglia G, Malhaire F, Rovira X, Catena J, Giraldo J, Pin JP, Fernández-Dueñas V, Goudet C, Nonell S, Nicoletti F, Llebaria A, Ciruela F. Optical control of pain in vivo with a photoactive mGlu 5 receptor negative allosteric modulator. eLife 2017; 6:e23545. [PMID: 28395733 PMCID: PMC5388536 DOI: 10.7554/elife.23545] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 03/19/2017] [Indexed: 12/22/2022] Open
Abstract
Light-operated drugs constitute a major target in drug discovery, since they may provide spatiotemporal resolution for the treatment of complex diseases (i.e. chronic pain). JF-NP-26 is an inactive photocaged derivative of the metabotropic glutamate type 5 (mGlu5) receptor negative allosteric modulator raseglurant. Violet light illumination of JF-NP-26 induces a photochemical reaction prompting the active-drug's release, which effectively controls mGlu5 receptor activity both in ectopic expressing systems and in striatal primary neurons. Systemic administration in mice followed by local light-emitting diode (LED)-based illumination, either of the thalamus or the peripheral tissues, induced JF-NP-26-mediated light-dependent analgesia both in neuropathic and in acute/tonic inflammatory pain models. These data offer the first example of optical control of analgesia in vivo using a photocaged mGlu5 receptor negative allosteric modulator. This approach shows potential for precisely targeting, in time and space, endogenous receptors, which may allow a better management of difficult-to-treat disorders.
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Affiliation(s)
- Joan Font
- MCS, Laboratory of Medicinal Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Unitat de Bioestadística, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Marc López-Cano
- Departament de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, IDIBELL, Universitat de Barcelona, Barcelona, Spain
- Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | | | | | | | | | | | - Fanny Malhaire
- IGF, CNRS, INSERM, Univ. Montpellier, Montpellier, France
| | - Xavier Rovira
- IGF, CNRS, INSERM, Univ. Montpellier, Montpellier, France
| | - Juanlo Catena
- MCS, Laboratory of Medicinal Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
| | - Jesús Giraldo
- Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Unitat de Bioestadística, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Network Biomedical Research Center on Mental Health (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain
| | | | - Víctor Fernández-Dueñas
- Departament de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, IDIBELL, Universitat de Barcelona, Barcelona, Spain
- Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Cyril Goudet
- IGF, CNRS, INSERM, Univ. Montpellier, Montpellier, France
| | - Santi Nonell
- Institut Químic de Sarrià, Universitat Ramon Llull, Barcelona, Spain
| | - Ferdinando Nicoletti
- I.R.C.C.S. Neuromed, Pozzilli, Italy
- Department of Physiology and Pharmacology, University Sapienza, Rome, Italy
| | - Amadeu Llebaria
- MCS, Laboratory of Medicinal Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
| | - Francisco Ciruela
- Departament de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, IDIBELL, Universitat de Barcelona, Barcelona, Spain
- Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
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Raos BJ, Graham ES, Unsworth CP. Investigation of the Ca2+ response of human hNT astrocytes to laser removal of cellular processes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2016:1750-1753. [PMID: 28268665 DOI: 10.1109/embc.2016.7591055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We demonstrate, for the first time, UV laser ablative microsurgery as a method for pruning astrocytic processes from live hNT astrocytic networks in vitro. Calcium fluorescence imaging was used to evaluate the cellular response to process ablation. The results showed that ablation of astrocyte processes induced an immediate increase in intracellular calcium level which propagated through the cells cytoplasm as a wave originating from the ablation site. The increased intracellular calcium dissipated from the body of the cell but remained high in the vicinity of the ablation site. Cell viability post ablation was confirmed by observing the integrity of the cell membrane. Ablation of astrocytic processes did not compromise cell viability whereas ablation of the cytoplasm using the same laser energy resulted in cell lysis.
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Jakkampudi S, Abe M, Komori N, Takagi R, Furukawa K, Katan C, Sawada W, Takahashi N, Kasai H. Design and Synthesis of a 4-Nitrobromobenzene Derivative Bearing an Ethylene Glycol Tetraacetic Acid Unit for a New Generation of Caged Calcium Compounds with Two-Photon Absorption Properties in the Near-IR Region and Their Application in Vivo. ACS OMEGA 2016; 1:193-201. [PMID: 31457124 PMCID: PMC6640811 DOI: 10.1021/acsomega.6b00119] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 07/25/2016] [Indexed: 06/10/2023]
Abstract
Among biologically active compounds, calcium ions (Ca2+) are one of the most important species in cell physiological functions. Development of new calcium chelators with two-photon absorption (TPA) properties is a state-of-the-art challenge for chemists. In this study, we report the first and efficient synthesis of 5-bromo-2-nitrobenzyl-substituted ethylene glycol tetraacetic acid (EGTA) as a platform for a new generation of calcium chelators with TPA properties in the near-infrared region. New calcium chelators with high TPA properties, that is, a two-photon (TP) fragmentation efficiency of δu = 20.7 GM at 740 nm for 2-(4-nitrophenyl)benzofuran (NPBF)-substituted EGTA (NPBF-EGTA, K d = 272 nM) and δu = 7.8 GM at 800 nm for 4-amino-4'-nitro-1,1'-biphenyl (BP)-substituted EGTA (BP-EGTA, K d = 440 nM) derivatives, were synthesized using Suzuki-Miyaura coupling reactions of the bromide with benzofuran-2-boronic acid and 4-(dimethylamino)phenyl boronic acid, respectively. The corresponding acetoxymethyl (AM) esters were prepared and successfully applied to the Ca2+-uncaging reaction triggered by TP photolysis in vivo.
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Affiliation(s)
- Satish Jakkampudi
- Department
of Chemistry & Research Center for Future Science, Graduate School
of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- JST-CREST, K’s Gobancho 7, Gobancho, Chiyodaku, Tokyo 102-0075, Japan
| | - Manabu Abe
- Department
of Chemistry & Research Center for Future Science, Graduate School
of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- JST-CREST, K’s Gobancho 7, Gobancho, Chiyodaku, Tokyo 102-0075, Japan
| | - Naomitsu Komori
- Department
of Chemistry & Research Center for Future Science, Graduate School
of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Ryukichi Takagi
- Department
of Chemistry & Research Center for Future Science, Graduate School
of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Ko Furukawa
- Center
for Instrumental Analysis, Institute for Research Promotion, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Claudine Katan
- Institut
des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université
Rennes 1, 35042 Rennes, France
| | - Wakako Sawada
- Laboratory
of Structural Physiology, CDBIM, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Noriko Takahashi
- Laboratory
of Structural Physiology, CDBIM, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Haruo Kasai
- JST-CREST, K’s Gobancho 7, Gobancho, Chiyodaku, Tokyo 102-0075, Japan
- Laboratory
of Structural Physiology, CDBIM, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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Decrock E, De Bock M, Wang N, Bultynck G, Giaume C, Naus CC, Green CR, Leybaert L. Connexin and pannexin signaling pathways, an architectural blueprint for CNS physiology and pathology? Cell Mol Life Sci 2015; 72:2823-51. [PMID: 26118660 PMCID: PMC11113968 DOI: 10.1007/s00018-015-1962-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 02/06/2023]
Abstract
The central nervous system (CNS) is composed of a highly heterogeneous population of cells. Dynamic interactions between different compartments (neuronal, glial, and vascular systems) drive CNS function and allow to integrate and process information as well as to respond accordingly. Communication within this functional unit, coined the neuro-glio-vascular unit (NGVU), typically relies on two main mechanisms: direct cell-cell coupling via gap junction channels (GJCs) and paracrine communication via the extracellular compartment, two routes to which channels composed of transmembrane connexin (Cx) or pannexin (Panx) proteins can contribute. Multiple isoforms of both protein families are present in the CNS and each CNS cell type is characterized by a unique Cx/Panx portfolio. Over the last two decades, research has uncovered a multilevel platform via which Cxs and Panxs can influence different cellular functions within a tissue: (1) Cx GJCs enable a direct cell-cell communication of small molecules, (2) Cx hemichannels and Panx channels can contribute to autocrine/paracrine signaling pathways, and (3) different structural domains of these proteins allow for channel-independent functions, such as cell-cell adhesion, interactions with the cytoskeleton, and the activation of intracellular signaling pathways. In this paper, we discuss current knowledge on their multifaceted contribution to brain development and to specific processes in the NGVU, including synaptic transmission and plasticity, glial signaling, vasomotor control, and blood-brain barrier integrity in the mature CNS. By highlighting both physiological and pathological conditions, it becomes evident that Cxs and Panxs can play a dual role in the CNS and that an accurate fine-tuning of each signaling mechanism is crucial for normal CNS physiology.
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Affiliation(s)
- Elke Decrock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Marijke De Bock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Nan Wang
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Louvain, Belgium
| | - Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, 75231 Paris Cedex 05, France
- University Pierre et Marie
Curie, ED, N°158, 75005 Paris, France
- MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005 Paris, France
| | - Christian C. Naus
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3 Canada
| | - Colin R. Green
- Department of Ophthalmology, The University of Auckland, Auckland, New Zealand
| | - Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
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Amatrudo JM, Olson JP, Agarwal HK, Ellis-Davies GCR. Caged compounds for multichromic optical interrogation of neural systems. Eur J Neurosci 2014; 41:5-16. [PMID: 25471355 DOI: 10.1111/ejn.12785] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/06/2014] [Accepted: 10/13/2014] [Indexed: 01/16/2023]
Abstract
Caged compounds are widely used by neurophysiologists to study many aspects of cellular signaling in glia and neurons. Biologically inert before irradiation, they can be loaded into cells via patch pipette or topically applied in situ to a defined concentration; photolysis releases the caged compound in a very rapid and spatially defined way. As caged compounds are exogenous optical probes, they include not only natural products such neurotransmitters, calcium and IP3 but non-natural products such as fluorophores, drugs and antibodies. In this Technical Spotlight we provide a short introduction to the uncaging technique by discussing the nitroaromatic caging chromophores most widely used in such experiments [e.g. α-carboxy-ortho-nitrobenyl (CNB), dimethoxynitrobenzyl (DMNB), 4-methoxy-7-nitroindolinyl (MNI) and 4-carboxymethoxy-7-nitroindolinyl (CDNI)]. We show that recently developed caging chromophores [rutheniumbipyridial (RuBi) and 7-diethylaminocoumarin (DEAC)450] that are photolyzed with blue light (~ 430-480 nm range) can be combined with traditional nitroaromatic caged compounds to enable two-color optical probing of neuronal function. For example, one-photon uncaging of either RuBi-GABA or DEAC450-GABA with a 473-nm laser is facile, and can block nonlinear currents (dendritic spikes or action potentials) evoked by two-photon uncaging of CDNI-Glu at 720 nm. We also show that two-photon uncaging of DEAC450-Glu and CDNI-GABA at 900 and 720 nm, respectively, can be used to fire and block action potentials. Our experiments illustrate that recently developed chromophores have taken uncaging out of the 'monochrome era', in which it has existed since 1978, so as to enable multichromic interrogation of neuronal function with single-synapse precision.
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Affiliation(s)
- Joseph M Amatrudo
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, 10029, USA
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14
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Metabotropic P2Y1 receptor signalling mediates astrocytic hyperactivity in vivo in an Alzheimer's disease mouse model. Nat Commun 2014; 5:5422. [PMID: 25406732 DOI: 10.1038/ncomms6422] [Citation(s) in RCA: 205] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 09/29/2014] [Indexed: 12/17/2022] Open
Abstract
Astrocytic network alterations have been reported in Alzheimer's disease (AD), but the underlying pathways have remained undefined. Here we measure astrocytic calcium, cerebral blood flow and amyloid-β plaques in vivo in a mouse model of AD using multiphoton microscopy. We find that astrocytic hyperactivity, consisting of single-cell transients and calcium waves, is most pronounced in reactive astrogliosis around plaques and is sometimes associated with local blood flow changes. We show that astroglial hyperactivity is reduced after P2 purinoreceptor blockade or nucleotide release through connexin hemichannels, but is augmented by increasing cortical ADP concentration. P2X receptor blockade has no effect, but inhibition of P2Y1 receptors, which are strongly expressed by reactive astrocytes surrounding plaques, completely normalizes astrocytic hyperactivity. Our data suggest that astroglial network dysfunction is mediated by purinergic signalling in reactive astrocytes, and that intervention aimed at P2Y1 receptors or hemichannel-mediated nucleotide release may help ameliorate network dysfunction in AD.
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Wang H. Establishment of an animal model of vascular dementia. Exp Ther Med 2014; 8:1599-1603. [PMID: 25289066 PMCID: PMC4186350 DOI: 10.3892/etm.2014.1926] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 05/20/2014] [Indexed: 02/01/2023] Open
Abstract
The aim of this study was to establish a mouse model of vascular dementia (VaD) in order to overcome the shortcomings of rat models of VaD, which include high production costs, difficult surgery, surgical trauma and high mortality. In this study, repeated ischemia-reperfusion of the total bilateral carotid artery in mice, combined with a reduction of blood pressure, was used to establish an animal model of VaD. A total of 40 Kunming mice (clean grade) were randomly divided into a sham group and a model group. Behavioral tests were performed for each group following the surgery, and the morphology of the hippocampus was analyzed. The results of the step-down avoidance test, water maze test and microscopy examinations confirmed that following surgery, learning and memory dysfunction was significantly increased in the model group. The results of the morphological observations showed that the number of hippocampal CA1 neurons was significantly decreased in the model group compared with that in the sham surgery group (P<0.01). In the present study, a mouse model of VaD was successfully established, which was simple, effective and reliable, and may be used in the future to investigate VaD.
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Affiliation(s)
- Hao Wang
- Department of Traditional Chinese Internal Medicine, China-Japan Friendship Hospital, Beijing 100029, P.R. China
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De Bock M, Decrock E, Wang N, Bol M, Vinken M, Bultynck G, Leybaert L. The dual face of connexin-based astroglial Ca(2+) communication: a key player in brain physiology and a prime target in pathology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2211-32. [PMID: 24768716 DOI: 10.1016/j.bbamcr.2014.04.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/11/2014] [Accepted: 04/12/2014] [Indexed: 12/21/2022]
Abstract
For decades, studies have been focusing on the neuronal abnormalities that accompany neurodegenerative disorders. Yet, glial cells are emerging as important players in numerous neurological diseases. Astrocytes, the main type of glia in the central nervous system , form extensive networks that physically and functionally connect neuronal synapses with cerebral blood vessels. Normal brain functioning strictly depends on highly specialized cellular cross-talk between these different partners to which Ca(2+), as a signaling ion, largely contributes. Altered intracellular Ca(2+) levels are associated with neurodegenerative disorders and play a crucial role in the glial responses to injury. Intracellular Ca(2+) increases in single astrocytes can be propagated toward neighboring cells as intercellular Ca(2+) waves, thereby recruiting a larger group of cells. Intercellular Ca(2+) wave propagation depends on two, parallel, connexin (Cx) channel-based mechanisms: i) the diffusion of inositol 1,4,5-trisphosphate through gap junction channels that directly connect the cytoplasm of neighboring cells, and ii) the release of paracrine messengers such as glutamate and ATP through hemichannels ('half of a gap junction channel'). This review gives an overview of the current knowledge on Cx-mediated Ca(2+) communication among astrocytes as well as between astrocytes and other brain cell types in physiology and pathology, with a focus on the processes of neurodegeneration and reactive gliosis. Research on Cx-mediated astroglial Ca(2+) communication may ultimately shed light on the development of targeted therapies for neurodegenerative disorders in which astrocytes participate. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.
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Affiliation(s)
- Marijke De Bock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium.
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mélissa Bol
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mathieu Vinken
- Department of Toxicology, Center for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, B-1090 Brussels, Belgium
| | - Geert Bultynck
- Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signalling, KULeuven, Campus Gasthuisberg O/N-I bus 802, B-3000 Leuven, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
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Kantevari S, Buskila Y, Ellis-Davies GCR. Synthesis and characterization of cell-permeant 6-nitrodibenzofuranyl-caged IP3. Photochem Photobiol Sci 2011; 11:508-13. [PMID: 21879138 DOI: 10.1039/c1pp05155e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have synthesized in a 6-nitrodibenzofuranyl (NDBF) derivative of inositol-1,4,5-trisphosphate (IP(3)) for efficient two-photon uncaging in living cells. As its hexakis acetoxymethyl ester, this caged compound may be applied at low concentration to the extracellular milieu to load the intact astrocytes in acutely isolated brain slices from the mouse cortex. Two-photon irradiation of single astrocytes evoked intracellular calcium signals that required 10% of the energy dosage compared to nitroveratyl (NV)-IP(3). Since NDBF-IP(3) has a 5-fold higher quantum yield than NV-IP(3), these data imply that photolysis of the new NDBF caged compound mobilized intracellular calcium about twice as efficiently as the NV cage.
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Affiliation(s)
- Srinivas Kantevari
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY 10029, USA
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Abstract
Microscopes using non-linear excitation of chromophores with pulsed near-IR light can generate highly localized foci of molecules in the electronic singlet state that are concentrated in volumes of less than one femtoliter. The three-dimensional confinement of excitation arises from the simultaneous absorption of two IR photons of approximately half the energy required for linear excitation. Two-photon microscopy is especially useful for two types of interrogation of neural processes. First, uncaging of signaling molecules such as glutamate, as stimulation is so refined it can be used to mimic normal unitary synaptic levels. In addition, uncaging allows complete control of the timing and position of stimulation, so the two-photon light beam provides the chemical neuroscientist with an "optical conductor's baton" which can command synaptic activity at will. A second powerful feature of two-photon microscopy is that when used for fluorescence imaging it enables the visualization of cellular structure and function in living animals at depths far beyond that possible with normal confocal microscopes. In this review I provide a survey of the many important applications of two-photon microscopy in these two fields of neuroscience, and suggest some areas for future technical development.
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Kantevari S, Gordon GRJ, MacVicar BA, Ellis-Davies GCR. A practical guide to the synthesis and use of membrane-permeant acetoxymethyl esters of caged inositol polyphosphates. Nat Protoc 2011; 6:327-37. [PMID: 21372813 DOI: 10.1038/nprot.2010.194] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This protocol describes a method for efficient chemical synthesis of an analog of inositol-1,4,5-trisphosphate (IP(3)) hexakis acetoxymethyl ester having an ortho-nitroveratryl photochemical caging group on the 6-hydroxyl position. The six esters render the probe membrane permeant, such that it can be loaded into intact living cells in vitro or in vivo. Inside cells, the caged IP(3) is inert until activated by two-photon excitation at 720 nm. The photoliberated signaling molecule can mobilize release of Ca(2+) from intracellular stores on the endoplasmic reticulum. When co-loaded with the fluorescent Ca(2+) indicator rhod-2, one laser can be used for stimulating and monitoring intracellular Ca(2+) signaling with single-cell resolution. This protocol has chemistry and biology sections; the former describes the organic synthesis of the caged IP(3), which requires 12 d, and the latter an application to a day-long study of astrocyte-regulated neuronal function in living brain slices acutely isolated from rats. As Ca(2+) is the single most important intracellular second messenger and the IP(3)-Ca(2+) signaling cascade is used by many cells to produce increases in Ca(2+) concentration, this method should be widely applicable for the study of a variety of physiological processes in intact biological systems.
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Affiliation(s)
- Srinivas Kantevari
- Department of Neuroscience, Mount Sinai School of Medicine, New York, New York, USA
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