201
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Armbruster M, Dulla CG, Diamond JS. Effects of fluorescent glutamate indicators on neurotransmitter diffusion and uptake. eLife 2020; 9:54441. [PMID: 32352378 PMCID: PMC7255799 DOI: 10.7554/elife.54441] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 04/29/2020] [Indexed: 01/10/2023] Open
Abstract
Genetically encoded fluorescent glutamate indicators (iGluSnFRs) enable neurotransmitter release and diffusion to be visualized in intact tissue. Synaptic iGluSnFR signal time courses vary widely depending on experimental conditions, often lasting 10–100 times longer than the extracellular lifetime of synaptically released glutamate estimated with uptake measurements. iGluSnFR signals typically also decay much more slowly than the unbinding kinetics of the indicator. To resolve these discrepancies, here we have modeled synaptic glutamate diffusion, uptake and iGluSnFR activation to identify factors influencing iGluSnFR signal waveforms. Simulations suggested that iGluSnFR competes with transporters to bind synaptically released glutamate, delaying glutamate uptake. Accordingly, synaptic transporter currents recorded from iGluSnFR-expressing astrocytes in mouse cortex were slower than those in control astrocytes. Simulations also suggested that iGluSnFR reduces free glutamate levels in extrasynaptic spaces, likely limiting extrasynaptic receptor activation. iGluSnFR and lower affinity variants, nonetheless, provide linear indications of vesicle release, underscoring their value for optical quantal analysis.
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Affiliation(s)
- Moritz Armbruster
- Department of Neuroscience, Tufts University School of Medicine, Boston, United States
| | - Chris G Dulla
- Department of Neuroscience, Tufts University School of Medicine, Boston, United States
| | - Jeffrey S Diamond
- Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, United States
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202
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Cheyne JE, Montgomery JM. The cellular and molecular basis of in vivo synaptic plasticity in rodents. Am J Physiol Cell Physiol 2020; 318:C1264-C1283. [PMID: 32320288 DOI: 10.1152/ajpcell.00416.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Plasticity within the neuronal networks of the brain underlies the ability to learn and retain new information. The initial discovery of synaptic plasticity occurred by measuring synaptic strength in vivo, applying external stimulation and observing an increase in synaptic strength termed long-term potentiation (LTP). Many of the molecular pathways involved in LTP and other forms of synaptic plasticity were subsequently uncovered in vitro. Over the last few decades, technological advances in recording and imaging in live animals have seen many of these molecular mechanisms confirmed in vivo, including structural changes both pre- and postsynaptically, changes in synaptic strength, and changes in neuronal excitability. A well-studied aspect of neuronal plasticity is the capacity of the brain to adapt to its environment, gained by comparing the brains of deprived and experienced animals in vivo, and in direct response to sensory stimuli. Multiple in vivo studies have also strongly linked plastic changes to memory by interfering with the expression of plasticity and by manipulating memory engrams. Plasticity in vivo also occurs in the absence of any form of external stimulation, i.e., during spontaneous network activity occurring with brain development. However, there is still much to learn about how plasticity is induced during natural learning and how this is altered in neurological disorders.
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Affiliation(s)
- Juliette E Cheyne
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Johanna M Montgomery
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
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203
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Zott B, Simon MM, Hong W, Unger F, Chen-Engerer HJ, Frosch MP, Sakmann B, Walsh DM, Konnerth A. A vicious cycle of β amyloid-dependent neuronal hyperactivation. Science 2020; 365:559-565. [PMID: 31395777 DOI: 10.1126/science.aay0198] [Citation(s) in RCA: 352] [Impact Index Per Article: 88.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/02/2019] [Indexed: 12/11/2022]
Abstract
β-amyloid (Aβ)-dependent neuronal hyperactivity is believed to contribute to the circuit dysfunction that characterizes the early stages of Alzheimer's disease (AD). Although experimental evidence in support of this hypothesis continues to accrue, the underlying pathological mechanisms are not well understood. In this experiment, we used mouse models of Aβ-amyloidosis to show that hyperactivation is initiated by the suppression of glutamate reuptake. Hyperactivity occurred in neurons with preexisting baseline activity, whereas inactive neurons were generally resistant to Aβ-mediated hyperactivation. Aβ-containing AD brain extracts and purified Aβ dimers were able to sustain this vicious cycle. Our findings suggest a cellular mechanism of Aβ-dependent neuronal dysfunction that can be active before plaque formation.
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Affiliation(s)
- Benedikt Zott
- Institute of Neuroscience, Technical University of Munich, 80802 Munich, Germany.,Munich Cluster for Systems Neurology, Technical University of Munich, 80802 Munich, Germany
| | - Manuel M Simon
- Institute of Neuroscience, Technical University of Munich, 80802 Munich, Germany.,Munich Cluster for Systems Neurology, Technical University of Munich, 80802 Munich, Germany
| | - Wei Hong
- Laboratory for Neurodegenerative Research, Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
| | - Felix Unger
- Institute of Neuroscience, Technical University of Munich, 80802 Munich, Germany.,Munich Cluster for Systems Neurology, Technical University of Munich, 80802 Munich, Germany
| | - Hsing-Jung Chen-Engerer
- Institute of Neuroscience, Technical University of Munich, 80802 Munich, Germany.,Munich Cluster for Systems Neurology, Technical University of Munich, 80802 Munich, Germany
| | - Matthew P Frosch
- C.S. Kubik Laboratory for Neuropathology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Bert Sakmann
- Institute of Neuroscience, Technical University of Munich, 80802 Munich, Germany
| | - Dominic M Walsh
- Laboratory for Neurodegenerative Research, Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
| | - Arthur Konnerth
- Institute of Neuroscience, Technical University of Munich, 80802 Munich, Germany. .,Munich Cluster for Systems Neurology, Technical University of Munich, 80802 Munich, Germany
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204
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O'Banion CP, Yasuda R. Fluorescent sensors for neuronal signaling. Curr Opin Neurobiol 2020; 63:31-41. [PMID: 32203701 DOI: 10.1016/j.conb.2020.02.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 01/30/2020] [Accepted: 02/13/2020] [Indexed: 12/14/2022]
Abstract
Dissecting neuronal structure and function in relation to behavior is an immense undertaking. Researchers require imaging tools to study neuronal activity and biochemical signaling in situ in order to study the roles of neuronal and biochemical activity in information processing. A large number of genetically encoded fluorescent biosensors have been reported in the literature over the past few years as there is a push to develop new technology in neuroscience. Here, we review the classes and characteristics of fluorescent biosensors and highlight some considerations that investigators should keep in mind when choosing their tool. In addition, we discuss recent advances in biosensor development.
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Affiliation(s)
| | - Ryohei Yasuda
- Max Planck Florida Institute for Neuroscience, United States.
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205
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Kopach O, Zheng K, Rusakov DA. Optical monitoring of glutamate release at multiple synapses in situ detects changes following LTP induction. Mol Brain 2020; 13:39. [PMID: 32169106 PMCID: PMC7071671 DOI: 10.1186/s13041-020-00572-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/27/2020] [Indexed: 01/10/2023] Open
Abstract
Information processing and memory formation in the brain relies on release of the main excitatory neurotransmitter glutamate from presynaptic axonal specialisations. The classical Hebbian paradigm of synaptic memory, long-term potentiation (LTP) of transmission, has been widely associated with an increase in the postsynaptic receptor current. Whether and to what degree LTP induction also enhances presynaptic glutamate release has been the subject of debate. Here, we took advantage of the recently developed genetically encoded optical sensors of glutamate (iGluSnFR) to monitor its release at CA3-CA1 synapses in acute hippocampal slices, before and after the induction of LTP. We attempted to trace release events at multiple synapses simultaneously, by using two-photon excitation imaging in fast frame-scanning mode. We thus detected a significant increase in the average iGluSnFR signal during potentiation, which lasted for up to 90 min. This increase may reflect an increased amount of released glutamate or, alternatively, reduced glutamate binding to high-affinity glutamate transporters that compete with iGluSnFR.
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Affiliation(s)
- Olga Kopach
- Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
| | - Kaiyu Zheng
- Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
| | - Dmitri A Rusakov
- Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
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206
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Kilohertz two-photon fluorescence microscopy imaging of neural activity in vivo. Nat Methods 2020; 17:287-290. [PMID: 32123392 PMCID: PMC7199528 DOI: 10.1038/s41592-020-0762-7] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 01/23/2020] [Indexed: 01/03/2023]
Abstract
Understanding information processing in the brain requires us to monitor
neural activity at high spatiotemporal resolution. Using an ultrafast two-photon
fluorescence microscope (2PFM) empowered by all-optical laser scanning, we
imaged neural activity in vivo at up to 3,000 frames per second
and submicron spatial resolution. This ultrafast imaging method enabled
monitoring of both supra- and sub-threshold electrical activity down to 345
μm below the brain surface in head-fixed awake mice.
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207
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Yu X, Nagai J, Khakh BS. Improved tools to study astrocytes. Nat Rev Neurosci 2020; 21:121-138. [DOI: 10.1038/s41583-020-0264-8] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2020] [Indexed: 12/21/2022]
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208
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Ju N, Li Y, Liu F, Jiang H, Macknik SL, Martinez-Conde S, Tang S. Spatiotemporal functional organization of excitatory synaptic inputs onto macaque V1 neurons. Nat Commun 2020; 11:697. [PMID: 32019929 PMCID: PMC7000673 DOI: 10.1038/s41467-020-14501-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 01/14/2020] [Indexed: 11/09/2022] Open
Abstract
The integration of synaptic inputs onto dendrites provides the basis for neuronal computation. Whereas recent studies have begun to outline the spatial organization of synaptic inputs on individual neurons, the underlying principles related to the specific neural functions are not well understood. Here we perform two-photon dendritic imaging with a genetically-encoded glutamate sensor in awake monkeys, and map the excitatory synaptic inputs on dendrites of individual V1 superficial layer neurons with high spatial and temporal resolution. We find a functional integration and trade-off between orientation-selective and color-selective inputs in basal dendrites of individual V1 neurons. Synaptic inputs on dendrites are spatially clustered by stimulus feature, but functionally scattered in multidimensional feature space, providing a potential substrate of local feature integration on dendritic branches. Furthermore, apical dendrite inputs have larger receptive fields and longer response latencies than basal dendrite inputs, suggesting a dominant role for apical dendrites in integrating feedback in visual information processing.
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Affiliation(s)
- Niansheng Ju
- Peking University School of Life Sciences, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, 100871, Beijing, China.,IDG/McGovern Institute for Brain Research at Peking University, 100871, Beijing, China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, 100871, Beijing, China
| | - Yang Li
- Peking University School of Life Sciences, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, 100871, Beijing, China.,IDG/McGovern Institute for Brain Research at Peking University, 100871, Beijing, China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, 100871, Beijing, China
| | - Fang Liu
- Peking University School of Life Sciences, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, 100871, Beijing, China.,IDG/McGovern Institute for Brain Research at Peking University, 100871, Beijing, China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, 100871, Beijing, China
| | - Hongfei Jiang
- Peking University School of Life Sciences, 100871, Beijing, China.,Peking-Tsinghua Center for Life Sciences, 100871, Beijing, China.,IDG/McGovern Institute for Brain Research at Peking University, 100871, Beijing, China.,Key Laboratory of Machine Perception (Ministry of Education), Peking University, 100871, Beijing, China
| | - Stephen L Macknik
- State University of New York, Downstate Health Sciences University, 11203, Brooklyn, NY, USA
| | - Susana Martinez-Conde
- State University of New York, Downstate Health Sciences University, 11203, Brooklyn, NY, USA
| | - Shiming Tang
- Peking University School of Life Sciences, 100871, Beijing, China. .,Peking-Tsinghua Center for Life Sciences, 100871, Beijing, China. .,IDG/McGovern Institute for Brain Research at Peking University, 100871, Beijing, China. .,Key Laboratory of Machine Perception (Ministry of Education), Peking University, 100871, Beijing, China.
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209
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Synaptotagmin 1 oligomers clamp and regulate different modes of neurotransmitter release. Proc Natl Acad Sci U S A 2020; 117:3819-3827. [PMID: 32015138 PMCID: PMC7035618 DOI: 10.1073/pnas.1920403117] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Release of neurotransmitters relies on submillisecond coupling of synaptic vesicle fusion to the triggering signal: AP-evoked presynaptic Ca2+ influx. The key player that controls exocytosis of the synaptic vesicle is the Ca2+ sensor synaptotagmin 1 (Syt1). While the Ca2+ activation of Syt1 has been extensively characterized, how Syt1 reversibly clamps vesicular fusion remains enigmatic. Here, using a targeted mutation combined with fluorescence imaging and electrophysiology, we show that the structural feature of Syt1 to self-oligomerize provides the molecular basis for clamping of spontaneous and asynchronous release but is not required for triggering of synchronous release. Our findings propose a mechanistic model that explains how Syt1 oligomers regulate different modes of transmitter release in neuronal synapses. Synaptotagmin 1 (Syt1) synchronizes neurotransmitter release to action potentials (APs) acting as the fast Ca2+ release sensor and as the inhibitor (clamp) of spontaneous and delayed asynchronous release. While the Syt1 Ca2+ activation mechanism has been well-characterized, how Syt1 clamps transmitter release remains enigmatic. Here we show that C2B domain-dependent oligomerization provides the molecular basis for the Syt1 clamping function. This follows from the investigation of a designed mutation (F349A), which selectively destabilizes Syt1 oligomerization. Using a combination of fluorescence imaging and electrophysiology in neocortical synapses, we show that Syt1F349A is more efficient than wild-type Syt1 (Syt1WT) in triggering synchronous transmitter release but fails to clamp spontaneous and synaptotagmin 7 (Syt7)-mediated asynchronous release components both in rescue (Syt1−/− knockout background) and dominant-interference (Syt1+/+ background) conditions. Thus, we conclude that Ca2+-sensitive Syt1 oligomers, acting as an exocytosis clamp, are critical for maintaining the balance among the different modes of neurotransmitter release.
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210
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Shen Y, Nasu Y, Shkolnikov I, Kim A, Campbell RE. Engineering genetically encoded fluorescent indicators for imaging of neuronal activity: Progress and prospects. Neurosci Res 2020; 152:3-14. [PMID: 31991206 DOI: 10.1016/j.neures.2020.01.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/10/2020] [Accepted: 01/12/2020] [Indexed: 12/31/2022]
Abstract
Genetically encoded fluorescent indicators have transformed the way neuroscientists record neuronal activities and interrogate the nervous system in vivo. In this review, we discuss recent advances and new additions to the toolkit of indicators for calcium ion entry, membrane voltage change, neurotransmitter release, and other neuronal molecular processes. We highlight new engineering approaches for indicator design and development, and identify key areas for future improvement. From molecular tool developers' perspective, we aim to provide practical information for neuroscientists to evaluate and choose the most appropriate indicators for enabling new insights into brain function.
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Affiliation(s)
- Yi Shen
- Department of Chemistry, University of Alberta, Canada
| | - Yusuke Nasu
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Japan
| | | | - Anna Kim
- Department of Chemistry, University of Alberta, Canada
| | - Robert E Campbell
- Department of Chemistry, University of Alberta, Canada; Department of Chemistry, Graduate School of Science, The University of Tokyo, Japan.
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211
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Presynaptic MAST kinase controls opposing postsynaptic responses to convey stimulus valence in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2020; 117:1638-1647. [PMID: 31911469 PMCID: PMC6983413 DOI: 10.1073/pnas.1909240117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Animals need to quickly extract the valence information of sensory stimulus and assess whether the stimulus is attractive or aversive. Deciphering the molecular and circuit mechanisms that determine the stimulus valence is fundamental to understand how the nervous system generates the animal behaviors. Here we report that the AFD thermosensory neurons of C. elegans evoke in its postsynaptic AIY interneurons opposing neuronal responses that correlate with the valence of thermal stimuli. The C. elegans homologs of MAST kinase, Stomatin, and Diacylglycerol kinase function in AFD and regulate the opposing AIY responses. Our results further suggest that the alteration between excitatory and inhibitory AIY responses is mediated by controlling the balance of two opposing signals released from the AFD neurons. Presynaptic plasticity is known to modulate the strength of synaptic transmission. However, it remains unknown whether regulation in presynaptic neurons can evoke excitatory and inhibitory postsynaptic responses. We report here that the Caenorhabditis elegans homologs of MAST kinase, Stomatin, and Diacylglycerol kinase act in a thermosensory neuron to elicit in its postsynaptic neuron an excitatory or inhibitory response that correlates with the valence of thermal stimuli. By monitoring neural activity of the valence-coding interneuron in freely behaving animals, we show that the alteration between excitatory and inhibitory responses of the interneuron is mediated by controlling the balance of two opposing signals released from the presynaptic neuron. These alternative transmissions further generate opposing behavioral outputs necessary for the navigation on thermal gradients. Our findings suggest that valence-encoding interneuronal activity is determined by a presynaptic mechanism whereby MAST kinase, Stomatin, and Diacylglycerol kinase influence presynaptic outputs.
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212
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Eles JR, Kozai TDY. In vivo imaging of calcium and glutamate responses to intracortical microstimulation reveals distinct temporal responses of the neuropil and somatic compartments in layer II/III neurons. Biomaterials 2020; 234:119767. [PMID: 31954232 DOI: 10.1016/j.biomaterials.2020.119767] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 12/22/2019] [Accepted: 01/05/2020] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Intracortical microelectrode implants can generate a tissue response hallmarked by glial scarring and neuron cell death within 100-150 μm of the biomaterial device. Many have proposed that any performance decline in intracortical microstimulation (ICMS) due to this foreign body tissue response could be offset by increasing the stimulation amplitude. The mechanisms of this approach are unclear, however, as there has not been consensus on how increasing amplitude affects the spatial and temporal recruitment patterns of ICMS. APPROACH We clarify these unknowns using in vivo two-photon imaging of mice transgenically expressing the calcium sensor GCaMP6s in Thy1 neurons or virally expressing the glutamate sensor iGluSnFr in neurons. Calcium and neurotransmitter activity are tracked in the neuronal somas and neuropil during long-train stimulation in Layer II/III of somatosensory cortex. MAIN RESULTS Neural calcium activity and glutamate release are dense and strongest within 20-40 μm around the electrode, falling off with distance from the electrode. Neuronal calcium increases with higher amplitude stimulations. During prolonged stimulation trains, a sub-population of somas fail to maintain calcium activity. Interestingly, neuropil calcium activity is 3-fold less correlated to somatic calcium activity for cells that drop-out during the long stimulation train compared to cells that sustain activity throughout the train. Glutamate release is apparent only within 20 μm of the electrode and is sustained for at least 10s after cessation of the 15 and 20 μA stimulation train, but not lower amplitudes. SIGNIFICANCE These results demonstrate that increasing amplitude can increase the radius and intensity of neural recruitment, but it also alters the temporal response of some neurons. Further, dense glutamate release is highest within the first 20 μm of the electrode site even at high amplitudes, suggesting that there may be spatial limitations to the amplitude parameter space. The glutamate elevation outlasts stimulation, suggesting that high-amplitude stimulation may affect neurotransmitter re-uptake. This ultimately suggests that increasing the amplitude of ICMS device stimulation may fundamentally alter the temporal neural response, which could have implications for using amplitude to improve the ICMS effect or "offset" the effects of glial scarring.
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Affiliation(s)
- James R Eles
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Takashi D Y Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Center for the Neural Basis of Cognition, University of Pittsburgh, Carnegie Mellon University, Pittsburgh, PA, USA; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA; NeuroTech Center, University of Pittsburgh Brain Institute, Pittsburgh, PA, USA.
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213
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Andreoni A, Davis CM, Tian L. Measuring brain chemistry using genetically encoded fluorescent sensors. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2019. [DOI: 10.1016/j.cobme.2019.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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214
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Haggerty DL, Grecco GG, Reeves KC, Atwood B. Adeno-Associated Viral Vectors in Neuroscience Research. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2019; 17:69-82. [PMID: 31890742 PMCID: PMC6931098 DOI: 10.1016/j.omtm.2019.11.012] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Adeno-associated viral vectors (AAVs) are increasingly useful preclinical tools in neuroscience research studies for interrogating cellular and neurocircuit functions and mapping brain connectivity. Clinically, AAVs are showing increasing promise as viable candidates for treating multiple neurological diseases. Here, we briefly review the utility of AAVs in mapping neurocircuits, manipulating neuronal function and gene expression, and activity labeling in preclinical research studies as well as AAV-based gene therapies for diseases of the nervous system. This review highlights the vast potential that AAVs have for transformative research and therapeutics in the neurosciences.
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Affiliation(s)
- David L. Haggerty
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Gregory G. Grecco
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Medical Scientist Training Program, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Kaitlin C. Reeves
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Brady Atwood
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Stark Neurosciences Research Institute, Indianapolis, IN 46202, USA
- Corresponding author: Brady Atwood, PhD, Department of Pharmacology & Toxicology, Indiana University School of Medicine, 320 West 15th Street, NB-400C, Indianapolis, IN 46202, USA.
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215
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Coates C, Kerruth S, Helassa N, Török K. Kinetic Mechanisms of Fast Glutamate Sensing by Fluorescent Protein Probes. Biophys J 2019; 118:117-127. [PMID: 31787209 DOI: 10.1016/j.bpj.2019.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 11/01/2019] [Accepted: 11/11/2019] [Indexed: 01/18/2023] Open
Abstract
We have developed probes based on the bacterial periplasmic glutamate/aspartate binding protein with either an endogenously fluorescent protein or a synthetic fluorophore as the indicator of glutamate binding for studying the kinetic mechanism of glutamate binding. iGluSnFR variants termed iGluh, iGlum, and iGlul cover a broad range of Kd-s (5.8 μM and 2.1 and 50 mM, respectively), and a novel fluorescently labeled indicator, Fl-GluBP, has a Kd of 9.7 μM. The fluorescence response kinetics of all the probes are consistent with a two-step mechanism involving ligand binding and isomerization either of the apo or the ligand-bound binding protein. Although the previously characterized ultrafast indicators iGluu and iGluf had monophasic fluorescence enhancement that occurred in the rate limiting isomerization step, the sensors described here all have biphasic binding kinetics with fluorescence increases occurring both in the glutamate binding and the isomerization steps. For iGlum and iGlul, the data indicate prebinding conformational change followed by ligand binding. In contrast, for iGluh and Fl-GluBP, glutamate binding is followed by isomerization. Thus, the effects of structural heterogeneity introduced by single amino acid changes around the binding site on the kinetic path of interactions with glutamate are revealed. Remarkably, glutamate binding with a diffusion-limited rate constant to iGluh and Fl-GluBP is detected for the first time, hinting at the underlying mechanism of the supremely rapid activation of the highly homologous α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor by glutamate binding.
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Affiliation(s)
- Catherine Coates
- Molecular and Clinical Sciences Research Institute, St. George's University of London, London, United Kingdom
| | - Silke Kerruth
- Molecular and Clinical Sciences Research Institute, St. George's University of London, London, United Kingdom
| | - Nordine Helassa
- Molecular and Clinical Sciences Research Institute, St. George's University of London, London, United Kingdom
| | - Katalin Török
- Molecular and Clinical Sciences Research Institute, St. George's University of London, London, United Kingdom.
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216
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Scida K, Plaxco KW, Jamieson BG. High frequency, real-time neurochemical and neuropharmacological measurements in situ in the living body. Transl Res 2019; 213:50-66. [PMID: 31361988 DOI: 10.1016/j.trsl.2019.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/20/2019] [Accepted: 07/11/2019] [Indexed: 12/18/2022]
Abstract
The beautiful and complex brain machinery is perfectly synchronized, and our bodies have evolved to protect it against a myriad of potential threats. Shielded physically by the skull and chemically by the blood brain barrier, the brain processes internal and external information so that we can efficiently relate to the world that surrounds us while simultaneously and unconsciously controlling our vital functions. When coupled with the brittle nature of its internal chemical and electric signals, the brain's "armor" render accessing it a challenging and delicate endeavor that has historically limited our understanding of its structural and neurochemical intricacies. In this review, we briefly summarize the advancements made over the past 10 years to decode the brain's neurochemistry and neuropharmacology in situ, at the site of interest in the brain, with special focus on what we consider game-changing emerging technologies (eg, genetically encoded indicators and electrochemical aptamer-based sensors) and the challenges these must overcome before chronic, in situ chemosensing measurements become routine.
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Affiliation(s)
- Karen Scida
- Diagnostic Biochips, Inc., Glen Burnie, Maryland
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California
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217
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Werner CT, Williams CJ, Fermelia MR, Lin DT, Li Y. Circuit Mechanisms of Neurodegenerative Diseases: A New Frontier With Miniature Fluorescence Microscopy. Front Neurosci 2019; 13:1174. [PMID: 31736701 PMCID: PMC6834692 DOI: 10.3389/fnins.2019.01174] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/17/2019] [Indexed: 12/13/2022] Open
Abstract
Neurodegenerative diseases (NDDs), such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD), are devastating age-associated brain disorders. Significant efforts have been made to uncover the molecular and cellular pathogenic mechanisms that underlie NDDs. However, our understanding of the neural circuit mechanisms that mediate NDDs and associated symptomatic features have been hindered by technological limitations. Our inability to identify and track individual neurons longitudinally in subcortical brain regions that are preferentially targeted in NDDs has left gaping holes in our knowledge of NDDs. Recent development and advancement of the miniature fluorescence microscope (miniscope) has opened up new avenues for examining spatially and temporally coordinated activity from hundreds of cells in deep brain structures in freely moving rodents. In the present mini-review, we examine the capabilities of current and future miniscope tools and discuss the innovative applications of miniscope imaging techniques that can push the boundaries of our understanding of neural circuit mechanisms of NDDs into new territories.
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Affiliation(s)
- Craig T Werner
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, United States
| | | | - Mercedes R Fermelia
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, United States
| | - Da-Ting Lin
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, United States.,The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Yun Li
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, United States
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218
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Leopold AV, Shcherbakova DM, Verkhusha VV. Fluorescent Biosensors for Neurotransmission and Neuromodulation: Engineering and Applications. Front Cell Neurosci 2019; 13:474. [PMID: 31708747 PMCID: PMC6819510 DOI: 10.3389/fncel.2019.00474] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 10/08/2019] [Indexed: 12/21/2022] Open
Abstract
Understanding how neuronal activity patterns in the brain correlate with complex behavior is one of the primary goals of modern neuroscience. Chemical transmission is the major way of communication between neurons, however, traditional methods of detection of neurotransmitter and neuromodulator transients in mammalian brain lack spatiotemporal precision. Modern fluorescent biosensors for neurotransmitters and neuromodulators allow monitoring chemical transmission in vivo with millisecond precision and single cell resolution. Changes in the fluorescent biosensor brightness occur upon neurotransmitter binding and can be detected using fiber photometry, stationary microscopy and miniaturized head-mounted microscopes. Biosensors can be expressed in the animal brain using adeno-associated viral vectors, and their cell-specific expression can be achieved with Cre-recombinase expressing animals. Although initially fluorescent biosensors for chemical transmission were represented by glutamate biosensors, nowadays biosensors for GABA, acetylcholine, glycine, norepinephrine, and dopamine are available as well. In this review, we overview functioning principles of existing intensiometric and ratiometric biosensors and provide brief insight into the variety of neurotransmitter-binding proteins from bacteria, plants, and eukaryotes including G-protein coupled receptors, which may serve as neurotransmitter-binding scaffolds. We next describe a workflow for development of neurotransmitter and neuromodulator biosensors. We then discuss advanced setups for functional imaging of neurotransmitter transients in the brain of awake freely moving animals. We conclude by providing application examples of biosensors for the studies of complex behavior with the single-neuron precision.
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Affiliation(s)
- Anna V Leopold
- Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Daria M Shcherbakova
- Department of Anatomy and Structural Biology, Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Vladislav V Verkhusha
- Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Department of Anatomy and Structural Biology, Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY, United States
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219
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Augusto E, Gambino F. Can NMDA Spikes Dictate Computations of Local Networks and Behavior? Front Mol Neurosci 2019; 12:238. [PMID: 31611774 PMCID: PMC6777373 DOI: 10.3389/fnmol.2019.00238] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 09/18/2019] [Indexed: 12/20/2022] Open
Abstract
Intelligence is the ability to learn appropriate responses to stimuli and the capacity to master new skills. Synaptic integration at the dendritic level is thought to be essential for this ability through linear and non-linear processing, by allowing neurons to be tuned to relevant information and to maximize adaptive behavior. Showing that dendrites are able to generate local computations that influence how animals perceive the world, form a new memory or learn a new skill was a break-through in neuroscience, since in the past they were seen as passive elements of the neurons, just funneling information to the soma. Here, we provide an overview of the role of dendritic integration in improving the neuronal network and behavioral performance. We focus on how NMDA spikes are generated and their role in neuronal computation for optimal behavioral output based on recent in vivo studies on rodents.
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Affiliation(s)
- Elisabete Augusto
- UMR5297 CNRS Centre Broca Nouvelle-Aquitaine, Interdisciplinary Institute for NeuroScience, University of Bordeaux, Bordeaux, France
| | - Frédéric Gambino
- UMR5297 CNRS Centre Broca Nouvelle-Aquitaine, Interdisciplinary Institute for NeuroScience, University of Bordeaux, Bordeaux, France
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220
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Live cell imaging of signaling and metabolic activities. Pharmacol Ther 2019; 202:98-119. [DOI: 10.1016/j.pharmthera.2019.06.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 05/31/2019] [Indexed: 12/15/2022]
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221
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Wang Y, DelRosso NV, Vaidyanathan TV, Cahill MK, Reitman ME, Pittolo S, Mi X, Yu G, Poskanzer KE. Accurate quantification of astrocyte and neurotransmitter fluorescence dynamics for single-cell and population-level physiology. Nat Neurosci 2019; 22:1936-1944. [PMID: 31570865 PMCID: PMC6858541 DOI: 10.1038/s41593-019-0492-2] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Accepted: 08/09/2019] [Indexed: 02/06/2023]
Abstract
Recent work examining astrocytic physiology centers on fluorescence imaging, due to development of sensitive fluorescent indicators and observation of spatiotemporally complex calcium activity. However, the field remains hindered in characterizing these dynamics, both within single cells and at the population level, because of the insufficiency of current region-of-interest (ROI)-based approaches to describe activity that is often spatially unfixed, size-varying, and propagative. Here, we present an analytical framework that releases astrocyte biologists from ROI-based tools. The Astrocyte Quantitative Analysis (AQuA) software takes an event-based perspective to model and accurately quantify complex calcium and neurotransmitter activity in fluorescence imaging datasets. We apply AQuA to a range of ex vivo and in vivo imaging data, and uncover novel physiological phenomena. Since AQuA is data-driven and based on machine learning principles, it can be applied across model organisms, fluorescent indicators, experimental modes, and imaging resolutions and speeds, enabling researchers to elucidate fundamental neural physiology.
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Affiliation(s)
- Yizhi Wang
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Arlington, VA, USA
| | - Nicole V DelRosso
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Trisha V Vaidyanathan
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Michelle K Cahill
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Michael E Reitman
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Silvia Pittolo
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Xuelong Mi
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Arlington, VA, USA
| | - Guoqiang Yu
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Arlington, VA, USA.
| | - Kira E Poskanzer
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, CA, USA. .,Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, USA. .,Kavli Institute for Fundamental Neuroscience, San Francisco, CA, USA.
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222
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Humeau Y, Choquet D. The next generation of approaches to investigate the link between synaptic plasticity and learning. Nat Neurosci 2019; 22:1536-1543. [PMID: 31477899 DOI: 10.1038/s41593-019-0480-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/26/2019] [Indexed: 12/28/2022]
Abstract
Activity-dependent synaptic plasticity has since long been proposed to represent the subcellular substrate of learning and memory, one of the most important behavioral processes through which we adapt to our environment. Despite the undisputed importance of synaptic plasticity for brain function, its exact contribution to learning processes in the context of cellular and connectivity modifications remains obscure. Causally bridging synaptic and behavioral modifications indeed remains limited by the available tools to measure and control synaptic strength and plasticity in vivo under behaviorally relevant conditions. After a brief summary of the current state of knowledge of the links between synaptic plasticity and learning, we will review and discuss the available and desired tools to progress in this endeavor.
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Affiliation(s)
- Yann Humeau
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, Bordeaux, France. .,Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, Bordeaux, France.
| | - Daniel Choquet
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, Bordeaux, France. .,Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, Bordeaux, France. .,Bordeaux Imaging Center, UMS 3420 CNRS - University of Bordeaux, US4 INSERM, Bordeaux, France.
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223
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Frank JA, Antonini MJ, Anikeeva P. Next-generation interfaces for studying neural function. Nat Biotechnol 2019; 37:1013-1023. [PMID: 31406326 PMCID: PMC7243676 DOI: 10.1038/s41587-019-0198-8] [Citation(s) in RCA: 111] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 06/26/2019] [Indexed: 01/06/2023]
Abstract
Monitoring and modulating the diversity of signals used by neurons and glia in a closed-loop fashion is necessary to establish causative links between biochemical processes within the nervous system and observed behaviors. As developments in neural-interface hardware strive to keep pace with rapid progress in genetically encoded and synthetic reporters and modulators of neural activity, the integration of multiple functional features becomes a key requirement and a pressing challenge in the field of neural engineering. Electrical, optical and chemical approaches have been used to manipulate and record neuronal activity in vivo, with a recent focus on technologies that both integrate multiple modes of interaction with neurons into a single device and enable bidirectional communication with neural circuits with enhanced spatiotemporal precision. These technologies not only are facilitating a greater understanding of the brain, spinal cord and peripheral circuits in the context of health and disease, but also are informing the development of future closed-loop therapies for neurological, neuro-immune and neuroendocrine conditions.
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Affiliation(s)
- James A Frank
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Marc-Joseph Antonini
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
- Harvard/MIT Health Science & Technology Graduate Program, Cambridge, MA, USA
| | - Polina Anikeeva
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA.
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Material Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
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224
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Kostyuk AI, Demidovich AD, Kotova DA, Belousov VV, Bilan DS. Circularly Permuted Fluorescent Protein-Based Indicators: History, Principles, and Classification. Int J Mol Sci 2019; 20:E4200. [PMID: 31461959 PMCID: PMC6747460 DOI: 10.3390/ijms20174200] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 08/22/2019] [Accepted: 08/24/2019] [Indexed: 12/28/2022] Open
Abstract
Genetically encoded biosensors based on fluorescent proteins (FPs) are a reliable tool for studying the various biological processes in living systems. The circular permutation of single FPs led to the development of an extensive class of biosensors that allow the monitoring of many intracellular events. In circularly permuted FPs (cpFPs), the original N- and C-termini are fused using a peptide linker, while new termini are formed near the chromophore. Such a structure imparts greater mobility to the FP than that of the native variant, allowing greater lability of the spectral characteristics. One of the common principles of creating genetically encoded biosensors is based on the integration of a cpFP into a flexible region of a sensory domain or between two interacting domains, which are selected according to certain characteristics. Conformational rearrangements of the sensory domain associated with ligand interaction or changes in the cellular parameter are transferred to the cpFP, changing the chromophore environment. In this review, we highlight the basic principles of such sensors, the history of their creation, and a complete classification of the available biosensors.
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Affiliation(s)
- Alexander I Kostyuk
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia
- Pirogov Russian National Research Medical University, Moscow 117997, Russia
| | | | - Daria A Kotova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia
| | - Vsevolod V Belousov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia
- Pirogov Russian National Research Medical University, Moscow 117997, Russia
- Institute for Cardiovascular Physiology, Georg August University Göttingen, D-37073 Göttingen, Germany
| | - Dmitry S Bilan
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia.
- Pirogov Russian National Research Medical University, Moscow 117997, Russia.
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225
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Soares C, Trotter D, Longtin A, Béïque JC, Naud R. Parsing Out the Variability of Transmission at Central Synapses Using Optical Quantal Analysis. Front Synaptic Neurosci 2019; 11:22. [PMID: 31474847 PMCID: PMC6702664 DOI: 10.3389/fnsyn.2019.00022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 07/31/2019] [Indexed: 12/11/2022] Open
Abstract
Properties of synaptic release dictates the core of information transfer in neural circuits. Despite decades of technical and theoretical advances, distinguishing bona fide information content from the multiple sources of synaptic variability remains a challenging problem. Here, we employed a combination of computational approaches with cellular electrophysiology, two-photon uncaging of MNI-Glutamate and imaging at single synapses. We describe and calibrate the use of the fluorescent glutamate sensor iGluSnFR and found that its kinetic profile is close to that of AMPA receptors, therefore providing several distinct advantages over slower methods relying on NMDA receptor activation (i.e., chemical or genetically encoded calcium indicators). Using an array of statistical methods, we further developed, and validated on surrogate data, an expectation-maximization algorithm that, by biophysically constraining release variability, extracts the quantal parameters n (maximum number of released vesicles) and p (unitary probability of release) from single-synapse iGluSnFR-mediated transients. Together, we present a generalizable mathematical formalism which, when applied to optical recordings, paves the way to an increasingly precise investigation of information transfer at central synapses.
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Affiliation(s)
- Cary Soares
- Department of Cellular and Molecular Medicine, uOttawa Brain and Mind Research Institute, Center for Neural Dynamics, University of Ottawa, Ottawa, ON, Canada
| | - Daniel Trotter
- Department of Physics, University of Ottawa, Ottawa, ON, Canada
| | - André Longtin
- Department of Cellular and Molecular Medicine, uOttawa Brain and Mind Research Institute, Center for Neural Dynamics, University of Ottawa, Ottawa, ON, Canada
- Department of Physics, University of Ottawa, Ottawa, ON, Canada
| | - Jean-Claude Béïque
- Department of Cellular and Molecular Medicine, uOttawa Brain and Mind Research Institute, Center for Neural Dynamics, University of Ottawa, Ottawa, ON, Canada
| | - Richard Naud
- Department of Cellular and Molecular Medicine, uOttawa Brain and Mind Research Institute, Center for Neural Dynamics, University of Ottawa, Ottawa, ON, Canada
- Department of Physics, University of Ottawa, Ottawa, ON, Canada
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226
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Kazemipour A, Novak O, Flickinger D, Marvin JS, Abdelfattah AS, King J, Borden PM, Kim JJ, Al-Abdullatif SH, Deal PE, Miller EW, Schreiter ER, Druckmann S, Svoboda K, Looger LL, Podgorski K. Kilohertz frame-rate two-photon tomography. Nat Methods 2019; 16:778-786. [PMID: 31363222 PMCID: PMC6754705 DOI: 10.1038/s41592-019-0493-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 06/14/2019] [Indexed: 11/25/2022]
Abstract
Point-scanning two-photon microscopy enables high-resolution imaging within scattering specimens such as the mammalian brain, but sequential acquisition of voxels fundamentally limits its speed. We developed a two-photon imaging technique that scans lines of excitation across a focal plane at multiple angles and computationally recovers high-resolution images, attaining voxel rates of over 1 billion Hz in structured samples. Using a static image as a prior for recording neural activity, we imaged visually evoked and spontaneous glutamate release across hundreds of dendritic spines in mice at depths over 250 µm and frame rates over 1 kHz. Dendritic glutamate transients in anesthetized mice are synchronized within spatially contiguous domains spanning tens of micrometers at frequencies ranging from 1-100 Hz. We demonstrate millisecond-resolved recordings of acetylcholine and voltage indicators, three-dimensional single-particle tracking and imaging in densely labeled cortex. Our method surpasses limits on the speed of raster-scanned imaging imposed by fluorescence lifetime.
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Affiliation(s)
- Abbas Kazemipour
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Department of Neurobiology, Stanford University, Stanford, CA, USA
| | - Ondrej Novak
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Second Medical Faculty, Charles University, Prague, Czech Republic
| | - Daniel Flickinger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | | | | | - Philip M Borden
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Jeong Jun Kim
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | | | - Parker E Deal
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Eric R Schreiter
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Shaul Druckmann
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Department of Neurobiology, Stanford University, Stanford, CA, USA
| | - Karel Svoboda
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Kaspar Podgorski
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
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227
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A genetically encoded fluorescent sensor for in vivo imaging of GABA. Nat Methods 2019; 16:763-770. [DOI: 10.1038/s41592-019-0471-2] [Citation(s) in RCA: 170] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 05/28/2019] [Indexed: 12/13/2022]
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228
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Pedelacq JD, Cabantous S. Development and Applications of Superfolder and Split Fluorescent Protein Detection Systems in Biology. Int J Mol Sci 2019; 20:ijms20143479. [PMID: 31311175 PMCID: PMC6678664 DOI: 10.3390/ijms20143479] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 07/08/2019] [Accepted: 07/08/2019] [Indexed: 01/08/2023] Open
Abstract
Molecular engineering of the green fluorescent protein (GFP) into a robust and stable variant named Superfolder GFP (sfGFP) has revolutionized the field of biosensor development and the use of fluorescent markers in diverse area of biology. sfGFP-based self-associating bipartite split-FP systems have been widely exploited to monitor soluble expression in vitro, localization, and trafficking of proteins in cellulo. A more recent class of split-FP variants, named « tripartite » split-FP, that rely on the self-assembly of three GFP fragments, is particularly well suited for the detection of protein–protein interactions. In this review, we describe the different steps and evolutions that have led to the diversification of superfolder and split-FP reporter systems, and we report an update of their applications in various areas of biology, from structural biology to cell biology.
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Affiliation(s)
- Jean-Denis Pedelacq
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 31077 Toulouse, France.
| | - Stéphanie Cabantous
- Centre de Recherche en Cancérologie de Toulouse (CRCT), Inserm, Université Paul Sabatier-Toulouse III, CNRS, 31037 Toulouse, France.
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229
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Beyene AG, Yang SJ, Landry MP. Review Article: Tools and trends for probing brain neurochemistry. JOURNAL OF VACUUM SCIENCE & TECHNOLOGY. A, VACUUM, SURFACES, AND FILMS : AN OFFICIAL JOURNAL OF THE AMERICAN VACUUM SOCIETY 2019; 37:040802. [PMID: 31235991 PMCID: PMC6559927 DOI: 10.1116/1.5051047] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/10/2018] [Accepted: 04/29/2019] [Indexed: 05/08/2023]
Abstract
The brain is composed of complex neuronal networks that interact on spatial and temporal scales that span several orders of magnitude. Uncovering how this circuitry gives rise to multifaceted phenomena such as perception, memory, and behavior remains one of the grand challenges in science today. A wide range of investigative methods have been developed to delve deeper into the inner workings of the brain, spanning the realms of molecular biology, genetics, chemistry, optics, and engineering, thereby forming a nexus of discovery that has accelerated our understanding of the brain. Whereas neuronal electrical excitability is a hallmark property of neurons, chemical signaling between neurons-mediated by hundreds of neurotransmitters, neuromodulators, hormones, and other signaling molecules-is equally important, but far more elusive in its regulation of brain function for motor control, learning, and behavior. To date, the brain's neurochemical state has been interrogated using classical tools borrowed from analytical chemistry, such as liquid chromatography and amperometry, and more recently, newly developed fluorescent sensors. Here, the authors review advances in the development of functional fluorescent probes that are beginning to expand their understanding of the neurochemical basis of brain function alongside device-based analytical tools that have already made extensive contributions to the field. The emphasis herein is on the paradigms of probe and device development, which follow certain design principles unique to the interrogation of brain chemistry.
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Affiliation(s)
- Abraham G Beyene
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720
| | - Sarah J Yang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720
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230
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Direct wavefront sensing enables functional imaging of infragranular axons and spines. Nat Methods 2019; 16:615-618. [PMID: 31209383 DOI: 10.1038/s41592-019-0434-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 04/29/2019] [Indexed: 11/09/2022]
Abstract
We advance two-photon microscopy for near-diffraction-limited imaging up to 850 µm below the pia in awake mice. Our approach combines direct wavefront sensing of light from a guidestar (formed by descanned fluorescence from Cy5.5-conjugated dextran in brain microvessels) with adaptive optics to compensate for tissue-induced aberrations in the wavefront. We achieve high signal-to-noise ratios in recordings of glutamate release from thalamocortical axons and calcium transients in spines of layer 5b basal dendrites during active tactile sensing.
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231
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Nelson NA, Wang X, Cook D, Carey EM, Nimmerjahn A. Imaging spinal cord activity in behaving animals. Exp Neurol 2019; 320:112974. [PMID: 31175843 DOI: 10.1016/j.expneurol.2019.112974] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 06/02/2019] [Accepted: 06/04/2019] [Indexed: 01/06/2023]
Abstract
The spinal cord is the primary neurological link between the brain and peripheral organs. How important it is in everyday life is apparent in patients with spinal cord injury or motoneuron disease, who have dramatically reduced musculoskeletal control or capacity to sense their environment. Despite its crucial role in sensory and motor processing little is known about the cellular and molecular signaling events that underlie spinal cord function under naturalistic conditions. While genetic, electrophysiological, pharmacological, and circuit tracing studies have revealed important roles for different molecularly defined neurons, these approaches insufficiently describe the moment-to-moment neuronal and non-neuronal activity patterns that underlie sensory-guided motor behaviors in health and disease. The recent development of imaging methods for real-time interrogation of cellular activity in the spinal cord of behaving mice has removed longstanding technical obstacles to spinal cord research and allowed new insight into how different cell types encode sensory information from mechanoreceptors and nociceptors in the skin. Here, we review the current state-of-the-art in interrogating cellular and microcircuit function in the spinal cord of behaving mammals and discuss current opportunities and technological challenges.
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Affiliation(s)
- Nicholas A Nelson
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA; Biologial Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92037, USA
| | - Xiang Wang
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Daniela Cook
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Erin M Carey
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Axel Nimmerjahn
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Shivange AV, Borden PM, Muthusamy AK, Nichols AL, Bera K, Bao H, Bishara I, Jeon J, Mulcahy MJ, Cohen B, O'Riordan SL, Kim C, Dougherty DA, Chapman ER, Marvin JS, Looger LL, Lester HA. Determining the pharmacokinetics of nicotinic drugs in the endoplasmic reticulum using biosensors. J Gen Physiol 2019; 151:738-757. [PMID: 30718376 PMCID: PMC6571994 DOI: 10.1085/jgp.201812201] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/05/2018] [Accepted: 01/09/2019] [Indexed: 12/27/2022] Open
Abstract
Nicotine dependence is thought to arise in part because nicotine permeates into the endoplasmic reticulum (ER), where it binds to nicotinic receptors (nAChRs) and begins an "inside-out" pathway that leads to up-regulation of nAChRs on the plasma membrane. However, the dynamics of nicotine entry into the ER are unquantified. Here, we develop a family of genetically encoded fluorescent biosensors for nicotine, termed iNicSnFRs. The iNicSnFRs are fusions between two proteins: a circularly permutated GFP and a periplasmic choline-/betaine-binding protein engineered to bind nicotine. The biosensors iNicSnFR3a and iNicSnFR3b respond to nicotine by increasing fluorescence at [nicotine] <1 µM, the concentration in the plasma and cerebrospinal fluid of a smoker. We target iNicSnFR3 biosensors either to the plasma membrane or to the ER and measure nicotine kinetics in HeLa, SH-SY5Y, N2a, and HEK293 cell lines, as well as mouse hippocampal neurons and human stem cell-derived dopaminergic neurons. In all cell types, we find that nicotine equilibrates in the ER within 10 s (possibly within 1 s) of extracellular application and leaves as rapidly after removal from the extracellular solution. The [nicotine] in the ER is within twofold of the extracellular value. We use these data to run combined pharmacokinetic and pharmacodynamic simulations of human smoking. In the ER, the inside-out pathway begins when nicotine becomes a stabilizing pharmacological chaperone for some nAChR subtypes, even at concentrations as low as ∼10 nM. Such concentrations would persist during the 12 h of a typical smoker's day, continually activating the inside-out pathway by >75%. Reducing nicotine intake by 10-fold decreases activation to ∼20%. iNicSnFR3a and iNicSnFR3b also sense the smoking cessation drug varenicline, revealing that varenicline also permeates into the ER within seconds. Our iNicSnFRs enable optical subcellular pharmacokinetics for nicotine and varenicline during an early event in the inside-out pathway.
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Affiliation(s)
- Amol V Shivange
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Philip M Borden
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Anand K Muthusamy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA
| | - Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Kallol Bera
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Huan Bao
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin, Madison, WI
| | - Ishak Bishara
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Janice Jeon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Matthew J Mulcahy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Bruce Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Saidhbhe L O'Riordan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Charlene Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA
| | - Edwin R Chapman
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin, Madison, WI
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
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233
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Burke KJ, Bender KJ. Modulation of Ion Channels in the Axon: Mechanisms and Function. Front Cell Neurosci 2019; 13:221. [PMID: 31156397 PMCID: PMC6533529 DOI: 10.3389/fncel.2019.00221] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 05/01/2019] [Indexed: 12/11/2022] Open
Abstract
The axon is responsible for integrating synaptic signals, generating action potentials (APs), propagating those APs to downstream synapses and converting them into patterns of neurotransmitter vesicle release. This process is mediated by a rich assortment of voltage-gated ion channels whose function can be affected on short and long time scales by activity. Moreover, neuromodulators control the activity of these proteins through G-protein coupled receptor signaling cascades. Here, we review cellular mechanisms and signaling pathways involved in axonal ion channel modulation and examine how changes to ion channel function affect AP initiation, AP propagation, and the release of neurotransmitter. We then examine how these mechanisms could modulate synaptic function by focusing on three key features of synaptic information transmission: synaptic strength, synaptic variability, and short-term plasticity. Viewing these cellular mechanisms of neuromodulation from a functional perspective may assist in extending these findings to theories of neural circuit function and its neuromodulation.
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Affiliation(s)
- Kenneth J Burke
- Neuroscience Graduate Program and Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, United States
| | - Kevin J Bender
- Neuroscience Graduate Program and Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, United States
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234
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High-speed imaging of glutamate release with genetically encoded sensors. Nat Protoc 2019; 14:1401-1424. [PMID: 30988508 DOI: 10.1038/s41596-019-0143-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/22/2019] [Indexed: 11/08/2022]
Abstract
The strength of an excitatory synapse depends on its ability to release glutamate and on the density of postsynaptic receptors. Genetically encoded glutamate indicators (GEGIs) allow eavesdropping on synaptic transmission at the level of cleft glutamate to investigate properties of the release machinery in detail. Based on the sensor iGluSnFR, we recently developed accelerated versions of GEGIs that allow investigation of synaptic release during 100-Hz trains. Here, we describe the detailed procedures for design and characterization of fast iGluSnFR variants in vitro, transfection of pyramidal cells in organotypic hippocampal cultures, and imaging of evoked glutamate transients with two-photon laser-scanning microscopy. As the released glutamate spreads from a point source-the fusing vesicle-it is possible to localize the vesicle fusion site with a precision exceeding the optical resolution of the microscope. By using a spiral scan path, the temporal resolution can be increased to 1 kHz to capture the peak amplitude of fast iGluSnFR transients. The typical time frame for these experiments is 30 min per synapse.
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235
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Aharoni D, Hoogland TM. Circuit Investigations With Open-Source Miniaturized Microscopes: Past, Present and Future. Front Cell Neurosci 2019; 13:141. [PMID: 31024265 PMCID: PMC6461004 DOI: 10.3389/fncel.2019.00141] [Citation(s) in RCA: 105] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 03/20/2019] [Indexed: 11/30/2022] Open
Abstract
The ability to simultaneously image the spatiotemporal activity signatures from many neurons during unrestrained vertebrate behaviors has become possible through the development of miniaturized fluorescence microscopes, or miniscopes, sufficiently light to be carried by small animals such as bats, birds and rodents. Miniscopes have permitted the study of circuits underlying song vocalization, action sequencing, head-direction tuning, spatial memory encoding and sleep to name a few. The foundation for these microscopes has been laid over the last two decades through academic research with some of this work resulting in commercialization. More recently, open-source initiatives have led to an even broader adoption of miniscopes in the neuroscience community. Open-source designs allow for rapid modification and extension of their function, which has resulted in a new generation of miniscopes that now permit wire-free or wireless recording, concurrent electrophysiology and imaging, two-color fluorescence detection, simultaneous optical actuation and read-out as well as wide-field and volumetric light-field imaging. These novel miniscopes will further expand the toolset of those seeking affordable methods to probe neural circuit function during naturalistic behaviors. Here, we will discuss the early development, present use and future potential of miniscopes.
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Affiliation(s)
- Daniel Aharoni
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Tycho M Hoogland
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands.,Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, Netherlands
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236
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Jensen TP, Zheng K, Cole N, Marvin JS, Looger LL, Rusakov DA. Multiplex imaging relates quantal glutamate release to presynaptic Ca 2+ homeostasis at multiple synapses in situ. Nat Commun 2019; 10:1414. [PMID: 30926781 PMCID: PMC6441074 DOI: 10.1038/s41467-019-09216-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 02/25/2019] [Indexed: 12/17/2022] Open
Abstract
Information processing by brain circuits depends on Ca2+-dependent, stochastic release of the excitatory neurotransmitter glutamate. Whilst optical glutamate sensors have enabled detection of synaptic discharges, understanding presynaptic machinery requires simultaneous readout of glutamate release and nanomolar presynaptic Ca2+ in situ. Here, we find that the fluorescence lifetime of the red-shifted Ca2+ indicator Cal-590 is Ca2+-sensitive in the nanomolar range, and employ it in combination with green glutamate sensors to relate quantal neurotransmission to presynaptic Ca2+ kinetics. Multiplexed imaging of individual and multiple synapses in identified axonal circuits reveals that glutamate release efficacy, but not its short-term plasticity, varies with time-dependent fluctuations in presynaptic resting Ca2+ or spike-evoked Ca2+ entry. Within individual presynaptic boutons, we find no nanoscopic co-localisation of evoked presynaptic Ca2+ entry with the prevalent glutamate release site, suggesting loose coupling between the two. The approach enables a better understanding of release machinery at central synapses.
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Affiliation(s)
- Thomas P Jensen
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
| | - Kaiyu Zheng
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
| | - Nicholas Cole
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, 20147, VA, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, 20147, VA, USA
| | - Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
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237
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Padamsey Z, Tong R, Emptage N. Optical Quantal Analysis Using Ca 2+ Indicators: A Robust Method for Assessing Transmitter Release Probability at Excitatory Synapses by Imaging Single Glutamate Release Events. Front Synaptic Neurosci 2019; 11:5. [PMID: 30886576 PMCID: PMC6409341 DOI: 10.3389/fnsyn.2019.00005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/14/2019] [Indexed: 11/13/2022] Open
Abstract
Despite evidence that presynaptic efficacy and plasticity influence circuit function and behavior in vivo, studies of presynaptic function remain challenging owing to the difficulty of assessing transmitter release in intact tissue. Electrophysiological analyses of transmitter release are indirect and cannot readily resolve basic presynaptic parameters, most notably transmitter release probability (p r), at single synapses. These issues can be circumvented by optical quantal analysis, which uses the all-or-none optical detection of transmitter release in order to calculate p r. Over the past two decades, we and others have successfully demonstrated that Ca2+ indicators can be strategically implemented to perform optical quantal analysis at single glutamatergic synapses in ex vivo and in vitro preparations. We have found that high affinity Ca2+ indicators can reliably detect spine Ca2+ influx generated by single quanta of glutamate, thereby enabling precise calculation of pr at single synapses. Importantly, we have shown this method to be robust to changes in postsynaptic efficacy, and to be sensitive to activity-dependent presynaptic changes at central synapses following the induction of long-term potentiation (LTP) and long-term depression (LTD). In this report, we describe how to use Ca2+-sensitive dyes to perform optical quantal analysis at single synapses in hippocampal slice preparations. The general technique we describe here can be applied to other glutamatergic synapses and can be used with other reporters of glutamate release, including recently improved genetically encoded Ca2+ and glutamate sensors. With ongoing developments in imaging techniques and genetically encoded probes, optical quantal analysis is a promising strategy for assessing presynaptic function and plasticity in vivo.
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Affiliation(s)
- Zahid Padamsey
- Center for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Rudi Tong
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Nigel Emptage
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
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238
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Lobas MA, Tao R, Nagai J, Kronschläger MT, Borden PM, Marvin JS, Looger LL, Khakh BS. A genetically encoded single-wavelength sensor for imaging cytosolic and cell surface ATP. Nat Commun 2019; 10:711. [PMID: 30755613 PMCID: PMC6372613 DOI: 10.1038/s41467-019-08441-5] [Citation(s) in RCA: 162] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 01/09/2019] [Indexed: 01/08/2023] Open
Abstract
Adenosine 5' triphosphate (ATP) is a universal intracellular energy source and an evolutionarily ancient, ubiquitous extracellular signal in diverse species. Here, we report the generation and characterization of single-wavelength genetically encoded fluorescent sensors (iATPSnFRs) for imaging extracellular and cytosolic ATP from insertion of circularly permuted superfolder GFP into the epsilon subunit of F0F1-ATPase from Bacillus PS3. On the cell surface and within the cytosol, iATPSnFR1.0 responds to relevant ATP concentrations (30 μM to 3 mM) with fast increases in fluorescence. iATPSnFRs can be genetically targeted to specific cell types and sub-cellular compartments, imaged with standard light microscopes, do not respond to other nucleotides and nucleosides, and when fused with a red fluorescent protein function as ratiometric indicators. After careful consideration of their modest pH sensitivity, iATPSnFRs represent promising reagents for imaging ATP in the extracellular space and within cells during a variety of settings, and for further application-specific refinements.
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Affiliation(s)
- Mark A Lobas
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095-1751, USA
- Koniku Inc., 740 Heinz Avenue, Berkeley, CA, 94710, USA
| | - Rongkun Tao
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095-1751, USA
| | - Jun Nagai
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095-1751, USA
| | - Mira T Kronschläger
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095-1751, USA
- Department of Neurophysiology, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090, Vienna, Austria
| | - Philip M Borden
- Janelia Research Campus, 19700 Helix Drive, Ashburn, VA, 20147, USA
| | | | - Loren L Looger
- Janelia Research Campus, 19700 Helix Drive, Ashburn, VA, 20147, USA.
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095-1751, USA.
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095-1751, USA.
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239
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Advances in Engineering and Application of Optogenetic Indicators for Neuroscience. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9030562] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Our ability to investigate the brain is limited by available technologies that can record biological processes in vivo with suitable spatiotemporal resolution. Advances in optogenetics now enable optical recording and perturbation of central physiological processes within the intact brains of model organisms. By monitoring key signaling molecules noninvasively, we can better appreciate how information is processed and integrated within intact circuits. In this review, we describe recent efforts engineering genetically-encoded fluorescence indicators to monitor neuronal activity. We summarize recent advances of sensors for calcium, potassium, voltage, and select neurotransmitters, focusing on their molecular design, properties, and current limitations. We also highlight impressive applications of these sensors in neuroscience research. We adopt the view that advances in sensor engineering will yield enduring insights on systems neuroscience. Neuroscientists are eager to adopt suitable tools for imaging neural activity in vivo, making this a golden age for engineering optogenetic indicators.
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240
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Wang W, Kim CK, Ting AY. Molecular tools for imaging and recording neuronal activity. Nat Chem Biol 2019; 15:101-110. [PMID: 30659298 DOI: 10.1038/s41589-018-0207-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 11/20/2018] [Indexed: 11/09/2022]
Abstract
To understand how the brain relates to behavior, it is essential to record neural activity in awake, behaving animals. To achieve this goal, a large variety of genetically encoded sensors have been developed to monitor and record the series of events following neuronal firing, including action potentials, intracellular calcium rise, neurotransmitter release and immediate early gene expression. In this Review, we discuss the existing genetically encoded tools for detecting and integrating neuronal activity in animals and highlight the remaining challenges and future opportunities for molecular biologists.
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Affiliation(s)
- Wenjing Wang
- Departments of Genetics, Biology, and Chemistry, Stanford University, Stanford, CA, USA.,Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA.,Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Christina K Kim
- Departments of Genetics, Biology, and Chemistry, Stanford University, Stanford, CA, USA
| | - Alice Y Ting
- Departments of Genetics, Biology, and Chemistry, Stanford University, Stanford, CA, USA. .,Chan Zuckerberg Biohub, San Francisco, CA, USA.
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241
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Bornschein G, Schmidt H. Synaptotagmin Ca 2+ Sensors and Their Spatial Coupling to Presynaptic Ca v Channels in Central Cortical Synapses. Front Mol Neurosci 2019; 11:494. [PMID: 30697148 PMCID: PMC6341215 DOI: 10.3389/fnmol.2018.00494] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/21/2018] [Indexed: 11/21/2022] Open
Abstract
Ca2+ concentrations drop rapidly over a distance of a few tens of nanometers from an open voltage-gated Ca2+ channel (Cav), thereby, generating a spatially steep and temporally short-lived Ca2+ gradient that triggers exocytosis of a neurotransmitter filled synaptic vesicle. These non-steady state conditions make the Ca2+-binding kinetics of the Ca2+ sensors for release and their spatial coupling to the Cavs important parameters of synaptic efficacy. In the mammalian central nervous system, the main release sensors linking action potential mediated Ca2+ influx to synchronous release are Synaptotagmin (Syt) 1 and 2. We review here quantitative work focusing on the Ca2+ kinetics of Syt2-mediated release. At present similar quantitative detail is lacking for Syt1-mediated release. In addition to triggering release, Ca2+ remaining bound to Syt after the first of two successive high-frequency activations was found to be capable of facilitating release during the second activation. More recently, the Ca2+ sensor Syt7 was identified as additional facilitation sensor. We further review how several recent functional studies provided quantitative insights into the spatial topographical relationships between Syts and Cavs and identified mechanisms regulating the sensor-to-channel coupling distances at presynaptic active zones. Most synapses analyzed in matured cortical structures were found to operate at tight, nanodomain coupling. For fast signaling synapses a developmental switch from loose, microdomain to tight, nanodomain coupling was found. The protein Septin5 has been known for some time as a developmentally down-regulated “inhibitor” of tight coupling, while Munc13-3 was found only recently to function as a developmentally up-regulated mediator of tight coupling. On the other hand, a highly plastic synapse was found to operate at loose coupling in the matured hippocampus. Together these findings suggest that the coupling topography and its regulation is a specificity of the type of synapse. However, to definitely draw such conclusion our knowledge of functional active zone topographies of different types of synapses in different areas of the mammalian brain is too incomplete.
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Affiliation(s)
- Grit Bornschein
- Carl-Ludwig Institute for Physiology, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Hartmut Schmidt
- Carl-Ludwig Institute for Physiology, Medical Faculty, University of Leipzig, Leipzig, Germany
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