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Singer W, Manthey M, Panford-Walsh R, Matt L, Geisler HS, Passeri E, Baj G, Tongiorgi E, Leal G, Duarte CB, Salazar IL, Eckert P, Rohbock K, Hu J, Strotmann J, Ruth P, Zimmermann U, Rüttiger L, Ott T, Schimmang T, Knipper M. BDNF-Live-Exon-Visualization (BLEV) Allows Differential Detection of BDNF Transcripts in vitro and in vivo. Front Mol Neurosci 2018; 11:325. [PMID: 30319348 PMCID: PMC6170895 DOI: 10.3389/fnmol.2018.00325] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 08/22/2018] [Indexed: 12/16/2022] Open
Abstract
Bdnf exon-IV and exon-VI transcripts are driven by neuronal activity and are involved in pathologies related to sleep, fear or memory disorders. However, how their differential transcription translates activity changes into long-lasting network changes is elusive. Aiming to trace specifically the network controlled by exon-IV and -VI derived BDNF during activity-dependent plasticity changes, we generated a transgenic reporter mouse for B DNF- l ive- e xon- v isualization (BLEV), in which expression of Bdnf exon-IV and -VI can be visualized by co-expression of CFP and YFP. CFP and YFP expression was differentially activated and targeted in cell lines, primary cultures and BLEV reporter mice without interfering with BDNF protein synthesis. CFP and YFP expression, moreover, overlapped with BDNF protein expression in defined hippocampal neuronal, glial and vascular locations in vivo. So far, activity-dependent BDNF cannot be explicitly monitored independent of basal BDNF levels. The BLEV reporter mouse therefore provides a new model, which can be used to test whether stimulus-induced activity-dependent changes in BDNF expression are instrumental for long-lasting plasticity modifications.
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Affiliation(s)
- Wibke Singer
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Marie Manthey
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Rama Panford-Walsh
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Lucas Matt
- Department of Pharmacology, Institute of Pharmacy, Toxicology and Clinical Pharmacy, University of Tübingen, Tübingen, Germany
| | - Hyun-Soon Geisler
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Eleonora Passeri
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Gabriele Baj
- B.R.A.I.N. Centre for Neuroscience, Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Enrico Tongiorgi
- B.R.A.I.N. Centre for Neuroscience, Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Graciano Leal
- Centre for Neuroscience and Cell Biology (CNC), Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Carlos B. Duarte
- Centre for Neuroscience and Cell Biology (CNC), Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Ivan L. Salazar
- Centre for Neuroscience and Cell Biology (CNC), Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Philipp Eckert
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Karin Rohbock
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Jing Hu
- Centre for Integrative Neuroscience (CIN), University of Tübingen, Tübingen, Germany
| | - Jörg Strotmann
- Department of Physiology, Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Peter Ruth
- Department of Pharmacology, Institute of Pharmacy, Toxicology and Clinical Pharmacy, University of Tübingen, Tübingen, Germany
| | - Ulrike Zimmermann
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Lukas Rüttiger
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Thomas Ott
- Transgenic Facility Tübingen, University of Tübingen, Tübingen, Germany
| | - Thomas Schimmang
- Instituto de Biologíay Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
| | - Marlies Knipper
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
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Ricard C, Arroyo ED, He CX, Portera-Cailliau C, Lepousez G, Canepari M, Fiole D. Two-photon probes for in vivo multicolor microscopy of the structure and signals of brain cells. Brain Struct Funct 2018; 223:3011-3043. [PMID: 29748872 PMCID: PMC6119111 DOI: 10.1007/s00429-018-1678-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 05/03/2018] [Indexed: 02/07/2023]
Abstract
Imaging the brain of living laboratory animals at a microscopic scale can be achieved by two-photon microscopy thanks to the high penetrability and low phototoxicity of the excitation wavelengths used. However, knowledge of the two-photon spectral properties of the myriad fluorescent probes is generally scarce and, for many, non-existent. In addition, the use of different measurement units in published reports further hinders the design of a comprehensive imaging experiment. In this review, we compile and homogenize the two-photon spectral properties of 280 fluorescent probes. We provide practical data, including the wavelengths for optimal two-photon excitation, the peak values of two-photon action cross section or molecular brightness, and the emission ranges. Beyond the spectroscopic description of these fluorophores, we discuss their binding to biological targets. This specificity allows in vivo imaging of cells, their processes, and even organelles and other subcellular structures in the brain. In addition to probes that monitor endogenous cell metabolism, studies of healthy and diseased brain benefit from the specific binding of certain probes to pathology-specific features, ranging from amyloid-β plaques to the autofluorescence of certain antibiotics. A special focus is placed on functional in vivo imaging using two-photon probes that sense specific ions or membrane potential, and that may be combined with optogenetic actuators. Being closely linked to their use, we examine the different routes of intravital delivery of these fluorescent probes according to the target. Finally, we discuss different approaches, strategies, and prerequisites for two-photon multicolor experiments in the brains of living laboratory animals.
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Affiliation(s)
- Clément Ricard
- Brain Physiology Laboratory, CNRS UMR 8118, 75006, Paris, France
- Faculté de Sciences Fondamentales et Biomédicales, Université Paris Descartes, PRES Sorbonne Paris Cité, 75006, Paris, France
- Fédération de Recherche en Neurosciences FR 3636, Paris, 75006, France
| | - Erica D Arroyo
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, USA
| | - Cynthia X He
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, USA
| | - Carlos Portera-Cailliau
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, USA
| | - Gabriel Lepousez
- Unité Perception et Mémoire, Département de Neuroscience, Institut Pasteur, 25 rue du Docteur Roux, 75724, Paris Cedex 15, France
| | - Marco Canepari
- Laboratory for Interdisciplinary Physics, UMR 5588 CNRS and Université Grenoble Alpes, 38402, Saint Martin d'Hères, France
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Grenoble, France
- Institut National de la Santé et Recherche Médicale (INSERM), Grenoble, France
| | - Daniel Fiole
- Unité Biothérapies anti-Infectieuses et Immunité, Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, BP 73, 91223, Brétigny-sur-Orge cedex, France.
- Human Histopathology and Animal Models, Infection and Epidemiology Department, Institut Pasteur, 28 rue du docteur Roux, 75725, Paris Cedex 15, France.
- ESRF-The European Synchrotron, 38043, Grenoble cedex, France.
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Leavesley SJ, Sweat B, Abbott C, Favreau P, Rich TC. A theoretical-experimental methodology for assessing the sensitivity of biomedical spectral imaging platforms, assays, and analysis methods. JOURNAL OF BIOPHOTONICS 2018; 11:10.1002/jbio.201600227. [PMID: 28485093 PMCID: PMC5680159 DOI: 10.1002/jbio.201600227] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 04/07/2017] [Accepted: 04/09/2017] [Indexed: 05/21/2023]
Abstract
Spectral imaging technologies have been used for many years by the remote sensing community. More recently, these approaches have been applied to biomedical problems, where they have shown great promise. However, biomedical spectral imaging has been complicated by the high variance of biological data and the reduced ability to construct test scenarios with fixed ground truths. Hence, it has been difficult to objectively assess and compare biomedical spectral imaging assays and technologies. Here, we present a standardized methodology that allows assessment of the performance of biomedical spectral imaging equipment, assays, and analysis algorithms. This methodology incorporates real experimental data and a theoretical sensitivity analysis, preserving the variability present in biomedical image data. We demonstrate that this approach can be applied in several ways: to compare the effectiveness of spectral analysis algorithms, to compare the response of different imaging platforms, and to assess the level of target signature required to achieve a desired performance. Results indicate that it is possible to compare even very different hardware platforms using this methodology. Future applications could include a range of optimization tasks, such as maximizing detection sensitivity or acquisition speed, providing high utility for investigators ranging from design engineers to biomedical scientists.
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Affiliation(s)
- Silas J. Leavesley
- Department of Chemical and Biomolecular Engineering, University of South Alabama
- Department of Pharmacology, University of South Alabama
- Center for Lung Biology, University of South Alabama
| | - Brenner Sweat
- Department of Chemical and Biomolecular Engineering, University of South Alabama
- IT Security & Governance, AM/NS Calvert
| | - Caitlyn Abbott
- Department of Chemical and Biomolecular Engineering, University of South Alabama
| | - Peter Favreau
- Department of Chemical and Biomolecular Engineering, University of South Alabama
- Basic Medical Sciences, University of South Alabama
- Morgridge Institute for Research, University of Wisconsin - Madison
| | - Thomas C. Rich
- Department of Pharmacology, University of South Alabama
- Center for Lung Biology, University of South Alabama
- College of Engineering, University of South Alabama
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Mercatelli R, Lana D, Bucciantini M, Giovannini MG, Cerbai F, Quercioli F, Zecchi-Orlandini S, Delfino G, Wenk GL, Nosi D. Clasmatodendrosis and β-amyloidosis in aging hippocampus. FASEB J 2015; 30:1480-91. [PMID: 26722005 DOI: 10.1096/fj.15-275503] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 12/08/2015] [Indexed: 01/25/2023]
Abstract
Alterations of the tightly interwoven neuron/astrocyte interactions are frequent traits of aging, but also favor neurodegenerative diseases, such as Alzheimer disease (AD). These alterations reflect impairments of the innate responses to inflammation-related processes, such as β-amyloid (Aβ) burdening. Multidisciplinary studies, spanning from the tissue to the molecular level, are needed to assess how neuron/astrocyte interactions are influenced by aging. Our study addressed this requirement by joining fluorescence-lifetime imaging microscopy/phasor multiphoton analysis with confocal microscopy, implemented with a novel method to separate spectrally overlapped immunofluorescence and Aβ autofluorescence. By comparing data from young control rats, chronically inflamed rats, and old rats, we identified age-specific alterations of neuron/astrocyte interactions in the hippocampus. We found a correlation between Aβ aggregation (+300 and +800% of aggregated Aβ peptide in chronically inflamed and oldvs.control rats, respectively) and fragmentation (clasmatodendrosis) of astrocyte projections (APJs) (+250 and +1300% of APJ fragments in chronically inflamed and oldvs.control rats, respectively). Clasmatodendrosis, in aged rats, associates with impairment of astrocyte-mediated Aβ clearance (-45% of Aβ deposits on APJs, and +33% of Aβ deposits on neurons in oldvs.chronically inflamed rats). Furthermore, APJ fragments colocalize with Aβ deposits and are involved in novel Aβ-mediated adhesions between neurons. These data define the effects of Aβ deposition on astrocyte/neuron interactions as a key topic in AD biology.-Mercatelli, R., Lana, D., Bucciantini, M., Giovannini, M. G., Cerbai, F., Quercioli, F., Zecchi-Orlandini, S., Delfino, G., Wenk, G. L., Nos, D. Clasmatodendrosis and β-amyloidosis in aging hippocampus.
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Affiliation(s)
- Raffaella Mercatelli
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
| | - Daniele Lana
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
| | - Monica Bucciantini
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
| | - Maria Grazia Giovannini
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
| | - Francesca Cerbai
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
| | - Franco Quercioli
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
| | - Sandra Zecchi-Orlandini
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
| | - Giovanni Delfino
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
| | - Gary L Wenk
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
| | - Daniele Nosi
- *Department of Chemistry "Ugo Schiff," Department of Health Sciences, Department of Biomedical Experimental and Clinical Sciences "Mario Serio," Department of Experimental and Clinical Medicine, and Department of Biology, University of Florence, Florence, Italy; National Institute of Optics, National Research Council (CNR), Florence, Italy; and Department of Psychology, The Ohio State University, Columbus, Ohio, USA
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5
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Thunemann M, Schmidt K, de Wit C, Han X, Jain RK, Fukumura D, Feil R. Correlative intravital imaging of cGMP signals and vasodilation in mice. Front Physiol 2014; 5:394. [PMID: 25352809 PMCID: PMC4196583 DOI: 10.3389/fphys.2014.00394] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/23/2014] [Indexed: 01/09/2023] Open
Abstract
Cyclic guanosine monophosphate (cGMP) is an important signaling molecule and drug target in the cardiovascular system. It is well known that stimulation of the vascular nitric oxide (NO)-cGMP pathway results in vasodilation. However, the spatiotemporal dynamics of cGMP signals themselves and the cGMP concentrations within specific cardiovascular cell types in health, disease, and during pharmacotherapy with cGMP-elevating drugs are largely unknown. To facilitate the analysis of cGMP signaling in vivo, we have generated transgenic mice that express fluorescence resonance energy transfer (FRET)-based cGMP sensor proteins. Here, we describe two models of intravital FRET/cGMP imaging in the vasculature of cGMP sensor mice: (1) epifluorescence-based ratio imaging in resistance-type vessels of the cremaster muscle and (2) ratio imaging by multiphoton microscopy within the walls of subcutaneous blood vessels accessed through a dorsal skinfold chamber. Both methods allow simultaneous monitoring of NO-induced cGMP transients and vasodilation in living mice. Detailed protocols of all steps necessary to perform and evaluate intravital imaging experiments of the vasculature of anesthetized mice including surgery, imaging, and data evaluation are provided. An image segmentation approach is described to estimate FRET/cGMP changes within moving structures such as the vessel wall during vasodilation. The methods presented herein should be useful to visualize cGMP or other biochemical signals that are detectable with FRET-based biosensors, such as cyclic adenosine monophosphate or Ca2+, and to correlate them with respective vascular responses. With further refinement and combination of transgenic mouse models and intravital imaging technologies, we envision an exciting future, in which we are able to “watch” biochemistry, (patho-)physiology, and pharmacotherapy in the context of a living mammalian organism.
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Affiliation(s)
- Martin Thunemann
- Interfakultäres Institut für Biochemie, University of Tübingen Tübingen, Germany
| | | | - Cor de Wit
- Institut für Physiologie, Universität zu Lübeck Lübeck, Germany
| | - Xiaoxing Han
- Edwin L. Steele Laboratory, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School Boston, MA, USA
| | - Rakesh K Jain
- Edwin L. Steele Laboratory, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School Boston, MA, USA
| | - Dai Fukumura
- Edwin L. Steele Laboratory, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School Boston, MA, USA
| | - Robert Feil
- Interfakultäres Institut für Biochemie, University of Tübingen Tübingen, Germany
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Spectral measurement of acceptor-to-donor extinction coefficient ratio in living cells. Micron 2014; 68:98-106. [PMID: 25464147 DOI: 10.1016/j.micron.2014.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 08/06/2014] [Accepted: 09/24/2014] [Indexed: 01/16/2023]
Abstract
This report presents a simple method named as sp-ECR to determine the molar extinction coefficient ratio (γ(λex)) of acceptor-to-donor in living cells at excitation wavelength λex, which is closely associated with the acceptor cross-excitation, the hardest issue of FRET quantification. sp-ECR determines γ(λex) by spectrally unmixing the emission spectrum of a donor-acceptor tandem construct under λex excitation without any additional references, such that this method can be performed under optimal imaging condition. We used sp-ECR to measure the γ(458) of Venus/Cerulean in living HepG2 cells on a confocal microscope, and the measured values were consistent with those obtained by lux-FRET method. We also used sp-ECR to measure the γ(458) values of Venus/Cerulean and YFP/CFP as well as YFP/GFP, the commonly used FRET FPs pairs in other two kinds of cancer cell lines on the confocal microscope, and found that the extinction coefficients of FPs depended on cell lines. After predetermining the γ(458) of Venus to ECFP, we used sp-ECR method to monitor the staurosporine (STS)-induced dynamical caspase-3 activation in single live A549 cells expressing SCAT3 by spectrally resolving the absolute FRET efficiency of SCAT3, and found that STS-induced caspase-3 activation in single cells is a very rapid process within 20 min.
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Zimmermann T, Marrison J, Hogg K, O'Toole P. Clearing up the signal: spectral imaging and linear unmixing in fluorescence microscopy. Methods Mol Biol 2014; 1075:129-48. [PMID: 24052349 DOI: 10.1007/978-1-60761-847-8_5] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The ongoing progress in fluorescence labeling and in microscope instrumentation allows the generation and the imaging of complex biological samples that contain increasing numbers of fluorophores. For the correct quantitative analysis of datasets with multiple fluorescence channels, it is essential that the signals of the different fluorophores are reliably separated. Due to the width of fluorescence spectra, this cannot always be achieved using the fluorescence filters in the microscope. In such cases spectral imaging of the fluorescence data and subsequent linear unmixing allows the separation even of highly overlapping fluorophores into pure signals. In this chapter, the problems of fluorescence cross talk are defined, the concept of spectral imaging and separation by linear unmixing is described, and an overview of the microscope types suitable for spectral imaging are given.
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Affiliation(s)
- Timo Zimmermann
- Advanced Light Microscopy Unit, Centre for Genomic Regulation, Barcelona, Spain
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Leavesley SJ, Britain AL, Cichon LK, Nikolaev VO, Rich TC. Assessing FRET using spectral techniques. Cytometry A 2013; 83:898-912. [PMID: 23929684 DOI: 10.1002/cyto.a.22340] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 06/13/2013] [Accepted: 06/28/2013] [Indexed: 01/21/2023]
Abstract
Förster resonance energy transfer (FRET) techniques have proven invaluable for probing the complex nature of protein-protein interactions, protein folding, and intracellular signaling events. These techniques have traditionally been implemented with the use of one or more fluorescence band-pass filters, either as fluorescence microscopy filter cubes, or as dichroic mirrors and band-pass filters in flow cytometry. In addition, new approaches for measuring FRET, such as fluorescence lifetime and acceptor photobleaching, have been developed. Hyperspectral techniques for imaging and flow cytometry have also shown to be promising for performing FRET measurements. In this study, we have compared traditional (filter-based) FRET approaches to three spectral-based approaches: the ratio of acceptor-to-donor peak emission, linear spectral unmixing, and linear spectral unmixing with a correction for direct acceptor excitation. All methods are estimates of FRET efficiency, except for one-filter set and three-filter set FRET indices, which are included for consistency with prior literature. In the first part of this study, spectrofluorimetric data were collected from a CFP-Epac-YFP FRET probe that has been used for intracellular cAMP measurements. All comparisons were performed using the same spectrofluorimetric datasets as input data, to provide a relevant comparison. Linear spectral unmixing resulted in measurements with the lowest coefficient of variation (0.10) as well as accurate fits using the Hill equation. FRET efficiency methods produced coefficients of variation of less than 0.20, while FRET indices produced coefficients of variation greater than 8.00. These results demonstrate that spectral FRET measurements provide improved response over standard, filter-based measurements. Using spectral approaches, single-cell measurements were conducted through hyperspectral confocal microscopy, linear unmixing, and cell segmentation with quantitative image analysis. Results from these studies confirmed that spectral imaging is effective for measuring subcellular, time-dependent FRET dynamics and that additional fluorescent signals can be readily separated from FRET signals, enabling multilabel studies of molecular interactions. © 2013 International Society for Advancement of Cytometry.
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Affiliation(s)
- Silas J Leavesley
- Department of Chemical and Biomolecular Engineering, University of South Alabama, Mobile, Alabama, 36688; Department of Pharmacology, University of South Alabama, Mobile, Alabama, 36688
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Simultaneous quantitative live cell imaging of multiple FRET-based biosensors. PLoS One 2013; 8:e61096. [PMID: 23613792 PMCID: PMC3628763 DOI: 10.1371/journal.pone.0061096] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 03/05/2013] [Indexed: 11/19/2022] Open
Abstract
We have developed a novel method for multi-color spectral FRET analysis which is used to study a system of three independent FRET-based molecular sensors composed of the combinations of only three fluorescent proteins. This method is made possible by a novel routine for computing the 3-D excitation/emission spectral fingerprint of FRET from reference measurements of the donor and acceptor alone. By unmixing the 3D spectrum of the FRET sample, the total relative concentrations of the fluorophores and their scaled FRET efficiencies are directly measured, from which apparent FRET efficiencies can be computed. If the FRET sample is composed of intramolecular FRET sensors it is possible to determine the total relative concentration of the sensors and then estimate absolute FRET efficiency of each sensor. Using multiple tandem constructs with fixed FRET efficiency as well as FRET-based calcium sensors with novel fluorescent protein combinations we demonstrate that the computed FRET efficiencies are accurate and changes in these quantities occur without crosstalk. We provide an example of this method's potential by demonstrating simultaneous imaging of spatially colocalized changes in [Ca(2+)], [cAMP], and PKA activity.
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Abstract
BACKGROUND One of the major hurdles in studying diabetes pathophysiology is the lack of adequate methodology that allows for direct and real-time determination of glucose transport and metabolism in cells and tissues. In this article, we present a new methodology that adopts frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) to visualize and quantify the dynamics of intracellular glucose within living cells using a biosensor protein based on fluorescence resonance energy transfer (FRET). METHOD The biosensor protein was developed by fusing a FRET pair, an AcGFP1 donor and a mCherry acceptor to N- and C- termini of a mutant glucose-binding protein (GBP), respectively. The probe was expressed and biosynthesized inside the cells, offering continuous monitoring of glucose dynamics in real time through fluorescence lifetime imaging microscopy (FLIM) measurement. RESULTS We transfected the deoxyribonucleic acid of the AcGFP1-GBP-mCherry sensor into murine myoblast cells, C2C12, and continuously monitored the changes in intracellular glucose concentrations in response to the variation in extracellular glucose, from which we determined glucose uptake and clearance rates. The distribution of intracellular glucose concentration was also characterized. We detected a high glucose concentration in a region close to the cell membrane and a low glucose concentration in a region close to the nucleus. The monoexponential decay of AcGFP1 was distinguished using FD-FLIM. CONCLUSIONS This work enables continuous glucose monitoring (CGM) within living cells using FD-FLIM and a biosensor protein. The sensor protein developed offers a new means for quantitatively analyzing glucose homeostasis at the cellular level. Data accumulated from these studies will help increase our understanding of the pathology of diabetes.
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Affiliation(s)
| | - Sha Jin
- Department of Biomedical Engineering, College of Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Kaiming Ye
- Department of Biomedical Engineering, College of Engineering, University of Arkansas, Fayetteville, Arkansas
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Ishikawa-Ankerhold HC, Ankerhold R, Drummen GPC. Advanced fluorescence microscopy techniques--FRAP, FLIP, FLAP, FRET and FLIM. Molecules 2012; 17:4047-132. [PMID: 22469598 PMCID: PMC6268795 DOI: 10.3390/molecules17044047] [Citation(s) in RCA: 284] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 03/21/2012] [Accepted: 03/21/2012] [Indexed: 12/19/2022] Open
Abstract
Fluorescence microscopy provides an efficient and unique approach to study fixed and living cells because of its versatility, specificity, and high sensitivity. Fluorescence microscopes can both detect the fluorescence emitted from labeled molecules in biological samples as images or photometric data from which intensities and emission spectra can be deduced. By exploiting the characteristics of fluorescence, various techniques have been developed that enable the visualization and analysis of complex dynamic events in cells, organelles, and sub-organelle components within the biological specimen. The techniques described here are fluorescence recovery after photobleaching (FRAP), the related fluorescence loss in photobleaching (FLIP), fluorescence localization after photobleaching (FLAP), Förster or fluorescence resonance energy transfer (FRET) and the different ways how to measure FRET, such as acceptor bleaching, sensitized emission, polarization anisotropy, and fluorescence lifetime imaging microscopy (FLIM). First, a brief introduction into the mechanisms underlying fluorescence as a physical phenomenon and fluorescence, confocal, and multiphoton microscopy is given. Subsequently, these advanced microscopy techniques are introduced in more detail, with a description of how these techniques are performed, what needs to be considered, and what practical advantages they can bring to cell biological research.
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Affiliation(s)
- Hellen C. Ishikawa-Ankerhold
- Ludwig Maximilian University of Munich, Institute of Anatomy and Cell Biology, Schillerstr. 42, 80336 München, Germany
| | - Richard Ankerhold
- Carl Zeiss Microimaging GmbH, Kistlerhofstr. 75, 81379 München, Germany
| | - Gregor P. C. Drummen
- Bionanoscience and Bio-Imaging Program, Cellular Stress and Ageing Program, Bio&Nano-Solutions, Helmutstr. 3A, 40472 Düsseldorf, Germany
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Leavesley SJ, Annamdevula N, Boni J, Stocker S, Grant K, Troyanovsky B, Rich TC, Alvarez DF. Hyperspectral imaging microscopy for identification and quantitative analysis of fluorescently-labeled cells in highly autofluorescent tissue. JOURNAL OF BIOPHOTONICS 2012; 5:67-84. [PMID: 21987373 PMCID: PMC3517021 DOI: 10.1002/jbio.201100066] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 09/05/2011] [Accepted: 09/07/2011] [Indexed: 05/03/2023]
Abstract
Standard fluorescence microscopy approaches rely on measurements at single excitation and emission bands to identify specific fluorophores and the setting of thresholds to quantify fluorophore intensity. This is often insufficient to reliably resolve and quantify fluorescent labels in tissues due to high autofluorescence. Here we describe the use of hyperspectral analysis techniques to resolve and quantify fluorescently labeled cells in highly autofluorescent lung tissue. This approach allowed accurate detection of green fluorescent protein (GFP) emission spectra, even when GFP intensity was as little as 15% of the autofluorescence intensity. GFP-expressing cells were readily quantified with zero false positives detected. In contrast, when the same images were analyzed using standard (single-band) thresholding approaches, either few GFP cells (high thresholds) or substantial false positives (intermediate and low thresholds) were detected. These results demonstrate that hyperspectral analysis approaches uniquely offer accurate and precise detection and quantification of fluorescence signals in highly autofluorescent tissues.
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Affiliation(s)
- Silas J Leavesley
- Department of Chemical and Biomolecular Engineering, University of South Alabama, 307 University Blvd. N., EGLB 264, Mobile, AL 36688, USA.
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13
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Ducros M, van 't Hoff M, van't Hoff M, Evrard A, Seebacher C, Schmidt EM, Charpak S, Oheim M. Efficient large core fiber-based detection for multi-channel two-photon fluorescence microscopy and spectral unmixing. J Neurosci Methods 2011; 198:172-80. [PMID: 21458489 DOI: 10.1016/j.jneumeth.2011.03.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 03/12/2011] [Accepted: 03/22/2011] [Indexed: 10/18/2022]
Abstract
Low-magnification high-numerical aperture objectives maximize the collection efficiency for scattered two-photon excited fluorescence (2PEF), but non-descanned detection schemes for such objectives demand optical components much bigger than standard microscope optics. Fiber coupling offers the possibility of removing bulky multi-channel detectors from the collection site, but coupling and transmission losses are generally believed to outweigh the benefits of optical fibers. We present here two new developments based on large-core fiber-optic fluorescence detection that illustrate clear advantages over conventional air-coupled 2PEF detection schemes. First, with minimal modifications of a commercial microscope, we efficiently couple the output of a 20×/NA0.95 objective to a large-core liquid light guide and we obtain a 7-fold collection gain when imaging astrocytes at 100 μm depth in acute brain slices of adult ALDH1L1-GFP mice. Second, combining 2PEF microscopy and 4-color detection on a custom microscope, mode scrambling inside a 2-mm plastic optical fiber is shown to cancel out the spatially non-uniform spectral sensitivity observed with air-coupled detectors. Spectral unmixing of images of brainbow mice taken with a fiber-coupled detector revealed a uniform color distribution of hippocampal neurons across a large field of view. Thus, fiber coupling improves both the efficiency and the homogeneity of 2PEF collection.
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Iwai S, Uyeda TQP. Myosin-actin interaction in Dictyostelium cells revealed by GFP-based strain sensor and validated linear spectral unmixing. Cytometry A 2010; 77:743-50. [DOI: 10.1002/cyto.a.20900] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Spectral unmixing: analysis of performance in the olfactory bulb in vivo. PLoS One 2009; 4:e4418. [PMID: 19198655 PMCID: PMC2635473 DOI: 10.1371/journal.pone.0004418] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Accepted: 12/23/2008] [Indexed: 11/25/2022] Open
Abstract
Background The generation of transgenic mice expressing combinations of fluorescent proteins has greatly aided the reporting of activity and identification of specific neuronal populations. Methods capable of separating multiple overlapping fluorescence emission spectra, deep in the living brain, with high sensitivity and temporal resolution are therefore required. Here, we investigate to what extent spectral unmixing addresses these issues. Methodology/Principal Findings Using fluorescence resonance energy transfer (FRET)-based reporters, and two-photon laser scanning microscopy with synchronous multichannel detection, we report that spectral unmixing consistently improved FRET signal amplitude, both in vitro and in vivo. Our approach allows us to detect odor-evoked FRET transients 180–250 µm deep in the brain, the first demonstration of in vivo spectral imaging and unmixing of FRET signals at depths greater than a few tens of micrometer. Furthermore, we determine the reporter efficiency threshold for which FRET detection is improved by spectral unmixing. Conclusions/Significance Our method allows the detection of small spectral variations in depth in the living brain, which is essential for imaging efficiently transgenic animals expressing combination of multiple fluorescent proteins.
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Chapter 12 Reflections on FRET imaging. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s0075-7535(08)00012-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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17
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Koushik SV, Vogel SS. Energy migration alters the fluorescence lifetime of Cerulean: implications for fluorescence lifetime imaging Forster resonance energy transfer measurements. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:031204. [PMID: 18601528 PMCID: PMC2556851 DOI: 10.1117/1.2940367] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Forster resonance energy transfer (FRET) is a physical phenomenon used to study molecular interactions in living cells. Changes in the fluorescence lifetime of proteins genetically tagged with a donor fluorophore, such as cyan fluorescent protein or Cerulean, are used to measure energy transfer to a protein tagged with an acceptor fluorophore (yellow fluorescent protein or Venus). Increased transfer efficiency is usually interpreted as closer proximity. Resonance energy transfer is also possible between identical fluorophores. This form of FRET is called energy migration resonance energy transfer (EM-RET). Theoretically, EM-RET should not alter the lifetime or emission spectrum measured from a population of fluorophores. We find a change in the fluorescent lifetime of Cerulean that correlates with energy migration and can result in significant errors when using Cerulean as a donor to measure FRET efficiencies based on fluorescence lifetimes [corrected]
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Affiliation(s)
- Srinagesh V Koushik
- Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland 20852, USA.
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Wessels JT, Busse AC, Mahrt J, Dullin C, Grabbe E, Mueller GA. In vivo imaging in experimental preclinical tumor research--a review. Cytometry A 2007; 71:542-9. [PMID: 17598185 DOI: 10.1002/cyto.a.20419] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The multiparametric molecular cell and tissue analysis in vitro and in vivo is characterized by rapid progress in the field of image generation technologies, sensor biotechnology, and computational modeling. Fascinating new potentials in unraveling the detailed functions of single cells, organs, and whole organisms are presently emerging and permit the close monitoring i.e. tumor development or basic cell development processes with an unprecedented multiplicity of promising investigative possibilities. To answer basic questions of in vivo tumor development and progression fluorescence based imaging techniques provide new insights into molecular pathways and targets. Genetic reporter systems (eGFP, DsRED) are available and high sensitive detection systems are on hand. These techniques could be used for in vitro assays and quantified e.g. by microscopy and CCD based readouts. The introduction of novel fluorescent dyes emitting in the near infrared range (NIR) combined with the development of sensitive detector systems and monochromatic powerful NIR-lasers for the first time permits the quantification and imaging of fluorescence and/or bioluminescence in deeper tissues. Laser based techniques particularly in the NIR-range (like two-photon microscopy) offer superb signal to noise ratios, and thus the potential to detect molecular targets in vivo. In combination with flat panel volumetric computed tomography (fpVCT), questions dealing e.g. with tumor size, tumor growth, and angiogenesis/vascularization could be answered noninvasively using the same animal. The resolution of down to 150 microm/each direction can be achieved using fpVCT. It is demonstrated by many groups that submillimeter resolutions can be achieved in small animal imaging at high sensitivity and molecular specificity. Since the resolution in preclinical small animal imaging is down to approximately 10 microm by the use of microCT and to subcellular resolutions using ( approximately 1 microm) microscope based systems, the advances of different techniques can now be combined to "multimodal" preclinical imaging and the possibilities for in vivo intravital cytometry now become within one's reach.
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Affiliation(s)
- J T Wessels
- Department of Nephrology/Rheumatology, Centre Internal Medicine, University Hospital Goettingen, Germany.
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