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Mateus JC, Sousa MM, Burrone J, Aguiar P. Beyond a Transmission Cable-New Technologies to Reveal the Richness in Axonal Electrophysiology. J Neurosci 2024; 44:e1446232023. [PMID: 38479812 PMCID: PMC10941245 DOI: 10.1523/jneurosci.1446-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 12/13/2023] [Accepted: 12/14/2023] [Indexed: 03/17/2024] Open
Abstract
The axon is a neuronal structure capable of processing, encoding, and transmitting information. This assessment contrasts with a limiting, but deeply rooted, perspective where the axon functions solely as a transmission cable of somatodendritic activity, sending signals in the form of stereotypical action potentials. This perspective arose, at least partially, because of the technical difficulties in probing axons: their extreme length-to-diameter ratio and intricate growth paths preclude the study of their dynamics through traditional techniques. Recent findings are challenging this view and revealing a much larger repertoire of axonal computations. Axons display complex signaling processes and structure-function relationships, which can be modulated via diverse activity-dependent mechanisms. Additionally, axons can exhibit patterns of activity that are dramatically different from those of their corresponding soma. Not surprisingly, many of these recent discoveries have been driven by novel technology developments, which allow for in vitro axon electrophysiology with unprecedented spatiotemporal resolution and signal-to-noise ratio. In this review, we outline the state-of-the-art in vitro toolset for axonal electrophysiology and summarize the recent discoveries in axon function it has enabled. We also review the increasing repertoire of microtechnologies for controlling axon guidance which, in combination with the available cutting-edge electrophysiology and imaging approaches, have the potential for more controlled and high-throughput in vitro studies. We anticipate that a larger adoption of these new technologies by the neuroscience community will drive a new era of experimental opportunities in the study of axon physiology and consequently, neuronal function.
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Affiliation(s)
- J C Mateus
- i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - M M Sousa
- i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - J Burrone
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
| | - P Aguiar
- i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
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Tong L, Han S, Xue Y, Chen M, Chen F, Ke W, Shu Y, Ding N, Bewersdorf J, Zhou ZJ, Yuan P, Grutzendler J. Single cell in vivo optogenetic stimulation by two-photon excitation fluorescence transfer. iScience 2023; 26:107857. [PMID: 37752954 PMCID: PMC10518705 DOI: 10.1016/j.isci.2023.107857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/01/2023] [Accepted: 09/06/2023] [Indexed: 09/28/2023] Open
Abstract
Optogenetic manipulation with single-cell resolution can be achieved by two-photon excitation. However, this frequently requires relatively high laser powers. Here, we developed a novel strategy that can improve the efficiency of current two-photon stimulation technologies by positioning fluorescent proteins or small fluorescent molecules with high two-photon cross-sections in the vicinity of opsins. This generates a highly localized source of endogenous single-photon illumination that can be tailored to match the optimal opsin absorbance. Through neuronal and vascular stimulation in the live mouse brain, we demonstrate the utility of this technique to achieve efficient opsin stimulation, without loss of cellular resolution. We also provide a theoretical framework for understanding the potential advantages and constrains of this methodology, with directions for future improvements. Altogether, this fluorescence transfer illumination method opens new possibilities for experiments difficult to implement in the live brain such as all-optical neural interrogation and control of regional cerebral blood flow.
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Affiliation(s)
- Lei Tong
- Department of Neurology, Yale School of Medicine, New Haven, CT 06511, USA
| | - Shanshan Han
- Department of Rehabilitation Medicine, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Yao Xue
- Department of Ophthalmology and Visual Science, Yale School of Medicine, New Haven, CT 06511, USA
| | - Minggang Chen
- Department of Ophthalmology and Visual Science, Yale School of Medicine, New Haven, CT 06511, USA
| | - Fuyi Chen
- Department of Neurology, Yale School of Medicine, New Haven, CT 06511, USA
| | - Wei Ke
- Department of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Yousheng Shu
- Department of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Ning Ding
- Department of Rehabilitation Medicine, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Joerg Bewersdorf
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06511, USA
- Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA
| | - Z. Jimmy Zhou
- Department of Ophthalmology and Visual Science, Yale School of Medicine, New Haven, CT 06511, USA
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06511, USA
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06511, USA
| | - Peng Yuan
- Department of Neurology, Yale School of Medicine, New Haven, CT 06511, USA
- Department of Rehabilitation Medicine, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Institute for Translational Brain Research, MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Jaime Grutzendler
- Department of Neurology, Yale School of Medicine, New Haven, CT 06511, USA
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06511, USA
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Kuznetsov IA, Berlew EE, Glantz ST, Hannanta-Anan P, Chow BY. Computational framework for single-cell spatiotemporal dynamics of optogenetic membrane recruitment. CELL REPORTS METHODS 2022; 2:100245. [PMID: 35880018 PMCID: PMC9308134 DOI: 10.1016/j.crmeth.2022.100245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 05/18/2022] [Accepted: 06/09/2022] [Indexed: 10/27/2022]
Abstract
We describe a modular computational framework for analyzing cell-wide spatiotemporal signaling dynamics in single-cell microscopy experiments that accounts for the experiment-specific geometric and diffractive complexities that arise from heterogeneous cell morphologies and optical instrumentation. Inputs are unique cell geometries and protein concentrations derived from confocal stacks and spatiotemporally varying environmental stimuli. After simulating the system with a model of choice, the output is convolved with the microscope point-spread function for direct comparison with the observable image. We experimentally validate this approach in single cells with BcLOV4, an optogenetic membrane recruitment system for versatile control over cell signaling, using a three-dimensional non-linear finite element model with all parameters experimentally derived. The simulations recapitulate observed subcellular and cell-to-cell variability in BcLOV4 signaling, allowing for inter-experimental differences of cellular and instrumentation origins to be elucidated and resolved for improved interpretive robustness. This single-cell approach will enhance optogenetics and spatiotemporally resolved signaling studies.
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Affiliation(s)
- Ivan A. Kuznetsov
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erin E. Berlew
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Spencer T. Glantz
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Pimkhuan Hannanta-Anan
- Department of Biomedical Engineering, School of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand
| | - Brian Y. Chow
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
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Parisutham V, Chhabra S, Ali MZ, Brewster RC. Tunable transcription factor library for robust quantification of regulatory properties in Escherichia coli. Mol Syst Biol 2022; 18:e10843. [PMID: 35694815 PMCID: PMC9189660 DOI: 10.15252/msb.202110843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 11/12/2022] Open
Abstract
Predicting the quantitative regulatory function of transcription factors (TFs) based on factors such as binding sequence, binding location, and promoter type is not possible. The interconnected nature of gene networks and the difficulty in tuning individual TF concentrations make the isolated study of TF function challenging. Here, we present a library of Escherichia coli strains designed to allow for precise control of the concentration of individual TFs enabling the study of the role of TF concentration on physiology and regulation. We demonstrate the usefulness of this resource by measuring the regulatory function of the zinc‐responsive TF, ZntR, and the paralogous TF pair, GalR/GalS. For ZntR, we find that zinc alters ZntR regulatory function in a way that enables activation of the regulated gene to be robust with respect to ZntR concentration. For GalR and GalS, we are able to demonstrate that these paralogous TFs have fundamentally distinct regulatory roles beyond differences in binding affinity.
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Affiliation(s)
- Vinuselvi Parisutham
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Shivani Chhabra
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Md Zulfikar Ali
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Robert C Brewster
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA.,Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA, USA
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Emmons SW, Yemini E, Zimmer M. Methods for analyzing neuronal structure and activity in Caenorhabditis elegans. Genetics 2021; 218:6303616. [PMID: 34151952 DOI: 10.1093/genetics/iyab072] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/20/2021] [Indexed: 11/12/2022] Open
Abstract
The model research animal Caenorhabditis elegans has unique properties making it particularly advantageous for studies of the nervous system. The nervous system is composed of a stereotyped complement of neurons connected in a consistent manner. Here, we describe methods for studying nervous system structure and function. The transparency of the animal makes it possible to visualize and identify neurons in living animals with fluorescent probes. These methods have been recently enhanced for the efficient use of neuron-specific reporter genes. Because of its simple structure, for a number of years, C. elegans has been at the forefront of connectomic studies defining synaptic connectivity by electron microscopy. This field is burgeoning with new, more powerful techniques, and recommended up-to-date methods are here described that encourage the possibility of new work in C. elegans. Fluorescent probes for single synapses and synaptic connections have allowed verification of the EM reconstructions and for experimental approaches to synapse formation. Advances in microscopy and in fluorescent reporters sensitive to Ca2+ levels have opened the way to observing activity within single neurons across the entire nervous system.
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Affiliation(s)
- Scott W Emmons
- Department of Genetics and Dominick Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 1041, USA
| | - Eviatar Yemini
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA
| | - Manuel Zimmer
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna 1090, Austria and.,Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna 1030, Austria
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Rozovsky A, Ebaston TM, Zaporozhets A, Bazylevich A, Tuchinsky H, Patsenker L, Gellerman G. Theranostic system for ratiometric fluorescence monitoring of peptide-guided targeted drug delivery. RSC Adv 2019; 9:32656-32664. [PMID: 35529716 PMCID: PMC9073098 DOI: 10.1039/c9ra06334j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 10/04/2019] [Indexed: 11/21/2022] Open
Abstract
Novel theranostic system that first combines a cancer-targeting peptide with a long-wavelength dual fluorescent dye IRD in order to provide ratiometric monitoring of anticancer drug delivery is developed and evaluated in pancreatic cancer cell line.
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Affiliation(s)
- Alex Rozovsky
- Department of Chemical Sciences
- Ariel University
- Ariel 40700
- Israel
| | - T. M. Ebaston
- Department of Chemical Sciences
- Ariel University
- Ariel 40700
- Israel
| | | | | | - Helena Tuchinsky
- Department of Molecular Biology
- Ariel University
- Ariel 40700
- Israel
| | - Leonid Patsenker
- Department of Chemical Sciences
- Ariel University
- Ariel 40700
- Israel
| | - Gary Gellerman
- Department of Chemical Sciences
- Ariel University
- Ariel 40700
- Israel
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