1
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Wang B, Ma T, Chen T, Nguyen T, Crouse E, Fleming SJ, Walker AS, Valakh V, Nehme R, Miller EW, Farhi SL, Babadi M. Robust self-supervised denoising of voltage imaging data using CellMincer. bioRxiv 2024:2024.04.12.589298. [PMID: 38659950 PMCID: PMC11042234 DOI: 10.1101/2024.04.12.589298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Voltage imaging enables high-throughput investigation of neuronal activity, yet its utility is often constrained by a low signal-to-noise ratio (SNR). Conventional denoising algorithms, such as those based on matrix factorization, impose limiting assumptions about the noise process and the spatiotemporal structure of the signal. While deep learning based denoising techniques offer greater adaptability, existing approaches fail to fully exploit the fast temporal dynamics and unique short- and long-range dependencies within voltage imaging datasets. Here, we introduce CellMincer, a novel self-supervised deep learning method designed specifically for denoising voltage imaging datasets. CellMincer operates on the principle of masking and predicting sparse sets of pixels across short temporal windows and conditions the denoiser on precomputed spatiotemporal auto-correlations to effectively model long-range dependencies without the need for large temporal denoising contexts. We develop and utilize a physics-based simulation framework to generate realistic datasets for rigorous hyperparameter optimization and ablation studies, highlighting the key role of conditioning the denoiser on precomputed spatiotemporal auto-correlations to achieve 3-fold further reduction in noise. Comprehensive benchmarking on both simulated and real voltage imaging datasets, including those with paired patch-clamp electrophysiology (EP) as ground truth, demonstrates CellMincer's state-of-the-art performance. It achieves substantial noise reduction across the entire frequency spectrum, enhanced detection of subthreshold events, and superior cross-correlation with ground-truth EP recordings. Finally, we demonstrate how CellMincer's addition to a typical voltage imaging data analysis workflow improves neuronal segmentation, peak detection, and ultimately leads to significantly enhanced separation of functional phenotypes.
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Affiliation(s)
- Brice Wang
- Data Sciences Platform (DSP), Broad Institute of MIT and Harvard, Cambridge, MA
| | - Tianle Ma
- Data Sciences Platform (DSP), Broad Institute of MIT and Harvard, Cambridge, MA
- Department of Computer Science and Engineering, Oakland University, Rochester, MI
| | - Theresa Chen
- Spatial Technology Platform (STP), Broad Institute of MIT and Harvard, Cambridge, MA
- Stanley Center for Psychiatric Research at the Broad Institute of MIT and Harvard, Cambridge, MA
| | - Trinh Nguyen
- Spatial Technology Platform (STP), Broad Institute of MIT and Harvard, Cambridge, MA
| | - Ethan Crouse
- Stanley Center for Psychiatric Research at the Broad Institute of MIT and Harvard, Cambridge, MA
| | - Stephen J. Fleming
- Data Sciences Platform (DSP), Broad Institute of MIT and Harvard, Cambridge, MA
| | - Alison S. Walker
- Departments of Molecular & Cell Biology and Chemistry and Helen Wills Neuroscience Institute, UC Berkeley
| | - Vera Valakh
- Spatial Technology Platform (STP), Broad Institute of MIT and Harvard, Cambridge, MA
- Stanley Center for Psychiatric Research at the Broad Institute of MIT and Harvard, Cambridge, MA
| | - Ralda Nehme
- Stanley Center for Psychiatric Research at the Broad Institute of MIT and Harvard, Cambridge, MA
| | - Evan W. Miller
- Departments of Molecular & Cell Biology and Chemistry and Helen Wills Neuroscience Institute, UC Berkeley
| | - Samouil L. Farhi
- Spatial Technology Platform (STP), Broad Institute of MIT and Harvard, Cambridge, MA
| | - Mehrtash Babadi
- Data Sciences Platform (DSP), Broad Institute of MIT and Harvard, Cambridge, MA
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2
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Gest AMM, Lazzari-Dean JR, Ortiz G, Yaeger-Weiss SK, Boggess SC, Miller EW. A red-emitting carborhodamine for monitoring and measuring membrane potential. Proc Natl Acad Sci U S A 2024; 121:e2315264121. [PMID: 38551837 PMCID: PMC10998576 DOI: 10.1073/pnas.2315264121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 01/25/2024] [Indexed: 04/02/2024] Open
Abstract
Biological membrane potentials, or voltages, are a central facet of cellular life. Optical methods to visualize cellular membrane voltages with fluorescent indicators are an attractive complement to traditional electrode-based approaches, since imaging methods can be high throughput, less invasive, and provide more spatial resolution than electrodes. Recently developed fluorescent indicators for voltage largely report changes in membrane voltage by monitoring voltage-dependent fluctuations in fluorescence intensity. However, it would be useful to be able to not only monitor changes but also measure values of membrane potentials. This study discloses a fluorescent indicator which can address both. We describe the synthesis of a sulfonated tetramethyl carborhodamine fluorophore. When this carborhodamine is conjugated with an electron-rich, methoxy (-OMe) containing phenylenevinylene molecular wire, the resulting molecule, CRhOMe, is a voltage-sensitive fluorophore with red/far-red fluorescence. Using CRhOMe, changes in cellular membrane potential can be read out using fluorescence intensity or lifetime. In fluorescence intensity mode, CRhOMe tracks fast-spiking neuronal action potentials (APs) with greater signal-to-noise than state-of-the-art BeRST 1 (another voltage-sensitive fluorophore). CRhOMe can also measure values of membrane potential. The fluorescence lifetime of CRhOMe follows a single exponential decay, substantially improving the quantification of membrane potential values using fluorescence lifetime imaging microscopy (FLIM). The combination of red-shifted excitation and emission, mono-exponential decay, and high voltage sensitivity enable fast FLIM recording of APs in cardiomyocytes. The ability to both monitor and measure membrane potentials with red light using CRhOMe makes it an important approach for studying biological voltages.
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Affiliation(s)
| | | | - Gloria Ortiz
- Department of Chemistry, University of California, Berkeley, CA 94720
| | | | - Steven C Boggess
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, CA 94720
- Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720
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3
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Gest AM, Grenier V, Miller EW. Optical Estimation of Membrane Potential Values Using Fluorescence Lifetime Imaging Microscopy and Hybrid Chemical-Genetic Voltage Indicators. Bioelectricity 2024; 6:34-41. [PMID: 38516638 PMCID: PMC10951690 DOI: 10.1089/bioe.2023.0027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024] Open
Abstract
Introduction Membrane potential (Vm), the voltage across a cell membrane, is an important biophysical phenomenon, central to the physiology of cells, tissues, and organisms. Voltage-sensitive fluorescent indicators are a powerful method for interrogating membrane potential in living systems, but most indicators are best suited for detecting changes in membrane potential rather than measuring values of the membrane potential. One promising approach is to use fluorescence lifetime imaging microscopy (FLIM) in combination of chemically synthesized dyes to estimate a value of membrane potential. However, a drawback is that chemically synthesized dyes show poor specificity of staining. Objectives To address this problem, we applied a chemical-genetic voltage imaging approach to FLIM to enable optical estimation of membrane potential values from genetically defined cells. Results In this report, we detail the characterization and evaluation of two of these systems in mammalian cells. We further validate the use of a FLIM-based chemical genetic voltage indicator in mammalian neurons. Conclusions Finally, we discuss opportunities for future improvements to chemical-genetic FLIM-based voltage indicators.
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Affiliation(s)
- Anneliese M.M. Gest
- Department of Chemistry, University of California, Berkeley, California, USA
| | - Vincent Grenier
- Department of Chemistry, University of California, Berkeley, California, USA
| | - Evan W. Miller
- Department of Chemistry, University of California, Berkeley, California, USA
- Department of Molecular & Cell Biology, University of California, Berkeley, California, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
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4
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Zheng S, Dadina N, Mozumdar D, Lesiak L, Martinez KN, Miller EW, Schepartz A. Long-term super-resolution inner mitochondrial membrane imaging with a lipid probe. Nat Chem Biol 2024; 20:83-92. [PMID: 37857992 PMCID: PMC10746544 DOI: 10.1038/s41589-023-01450-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 09/14/2023] [Indexed: 10/21/2023]
Abstract
The inner mitochondrial membrane (IMM) generates power to drive cell function, and its dynamics control mitochondrial health and cellular homeostasis. Here, we describe the cell-permeant, lipid-like small molecule MAO-N3 and use it to assemble high-density environmentally sensitive (HIDE) probes that selectively label and image the IMM in live cells and multiple cell states. MAO-N3 pairs with strain-promoted azide-alkyne click chemistry-reactive fluorophores to support HIDE imaging using confocal, structured illumination, single-molecule localization and stimulated emission depletion microscopy, all with significantly improved resistance to photobleaching. These probes generate images with excellent spatial and temporal resolution, require no genetic manipulations, are non-toxic in model cell lines and primary cardiomyocytes (even under conditions that amplify the effects of mitochondrial toxins) and can visualize mitochondrial dynamics for 12.5 h. This probe will enable comprehensive studies of IMM dynamics with high temporal and spatial resolution.
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Affiliation(s)
- Shuai Zheng
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
| | - Neville Dadina
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
| | - Deepto Mozumdar
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Lauren Lesiak
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
| | - Kayli N Martinez
- 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
| | - Alanna Schepartz
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA.
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, San Francisco, CA, USA.
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5
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Miller EW, Beckett EM, Roberts B, Cheatham D, Abelmann A, Pierce JS. Assessment of worst-case potential airborne asbestos exposure associated with the use of cosmetic talc: application of an exponential decay model. Environ Monit Assess 2023; 196:39. [PMID: 38097815 DOI: 10.1007/s10661-023-12091-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 11/03/2023] [Indexed: 12/18/2023]
Abstract
Talc is used in cosmetic products to confer desirable properties, such as moisture absorption and smooth texture, to the finished products. Concerns have been raised about the potential presence of asbestos in products containing cosmetic talc. Reconstruction of potential asbestos exposure from the use of cosmetic talc products (assuming a trace level of asbestos) requires consideration of consumer use patterns. Although application generally only lasts seconds, exposure theoretically may continue if the consumer remains in the immediate vicinity. Most published exposure measurements have not adequately characterized the potential for continued exposure. In this analysis, estimates and measurements of airborne asbestos fiber concentrations associated with cosmetic talc use from 10 published studies were used as inputs to an exponential decay model to estimate "worst-case" exposure during and following application. The resulting geometric mean 30-min time-weighted average (TWA) concentrations were 0.006 f/cc for both puff and shaker application, for diapering, 0.0001 f/cc (adult applying baby powder) and 0.0002 f/cc (infant), and for makeup application, 0.0005 f/cc. Application of an exponential decay model to measured or estimated asbestos concentrations associated with the use of cosmetic talc products yields a conservative means to comprehensively reconstruct such exposures. Moreover, our results support that, if a cosmetic talc powder product contained a trace level of asbestos fibers, the "worst-case" airborne asbestos exposure associated with its application is low.
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Affiliation(s)
- E W Miller
- Benchmark Risk Group, 333 Bridge St. NW, Suite 200, Grand Rapids, MI, 49504, USA.
| | | | - B Roberts
- Benchmark Risk Group, 333 Bridge St. NW, Suite 200, Grand Rapids, MI, 49504, USA
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6
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Turnbull JL, Golden RP, Benlian BR, Henn KM, Lipman SM, Miller EW. Mild and scalable synthesis of phosphonorhodamines. Chem Sci 2023; 14:11365-11373. [PMID: 37886078 PMCID: PMC10599461 DOI: 10.1039/d3sc02590j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 08/28/2023] [Indexed: 10/28/2023] Open
Abstract
Since their discovery in 1887, rhodamines have become indispensable fluorophores for biological imaging. Recent studies have extensively explored heteroatom substitution at the 10' position and a variety of substitution patterns on the 3',6' nitrogens. Although 3-carboxy- and 3-sulfono-rhodamines were first reported in the 19th century, the 3-phosphono analogues have never been reported. Here, we report a mild, scalable synthetic route to 3-phosphonorhodamines. We explore the substrate scope and investigate mechanistic details of an exogenous acid-free condensation. Tetramethyl-3-phosphonorhodamine (phosTMR) derivatives can be accessed on the 1.5 mmol scale in up to 98% yield (2 steps). phosTMR shows a 12- to 500-fold increase in water solubility relative to 3-carboxy and 3-sulfonorhodamine derivatives and has excellent chemical stability. Additionally, phosphonates allow for chemical derivatization; esterification of phosTMR facilitates intracellular delivery with localization profiles that differ from 3-carboxyrhodamines. The free phosphonate can be incorporated into a molecular wire scaffold to create a phosphonated rhodamine voltage reporter, phosphonoRhoVR. PhosRhoVR 1 can be synthesized in just 6 steps, with an overall yield of 37% to provide >400 mg of material, compared to a 6-step, ∼2% yield for the previously reported RhoVR 1. PhosRhoVR 1 possesses excellent voltage sensitivity (37% ΔF/F) and a 2-fold increase in cellular brightness compared to RhoVR 1.
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Affiliation(s)
- Joshua L Turnbull
- Department of Chemistry, University of California Berkeley CA 94720-1460 USA
| | - Ryan P Golden
- Department of Chemistry, University of California Berkeley CA 94720-1460 USA
| | - Brittany R Benlian
- Department of Molecular & Cell Biology, University of California Berkeley CA 94720-1460 USA
| | - Katharine M Henn
- Helen Wills Neuroscience Institute, University of California Berkeley CA 94720-1460 USA
| | - Soren M Lipman
- Department of Chemistry, University of California Berkeley CA 94720-1460 USA
| | - Evan W Miller
- Department of Chemistry, University of California Berkeley CA 94720-1460 USA
- Department of Molecular & Cell Biology, University of California Berkeley CA 94720-1460 USA
- Helen Wills Neuroscience Institute, University of California Berkeley CA 94720-1460 USA
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7
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Gest AMM, Lazzari-Dean JR, Ortiz G, Yaeger-Weiss SK, Boggess SC, Miller EW. A red-emitting carborhodamine for monitoring and measuring membrane potential. bioRxiv 2023:2023.10.06.561080. [PMID: 37873283 PMCID: PMC10592620 DOI: 10.1101/2023.10.06.561080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Biological membrane potentials, or voltages, are a central facet of cellular life. Optical methods to visualize cellular membrane voltages with fluorescent indicators are an attractive complement to traditional electrode-based approaches, since imaging methods can be high throughput, less invasive, and provide more spatial resolution than electrodes. Recently developed fluorescent indicators for voltage largely report changes in membrane voltage by monitoring voltage-dependent fluctuations in fluorescence intensity. However, it would be useful to be able to not only monitor changes, but also measure values of membrane potentials. This study discloses a new fluorescent indicator which can address both. We describe the synthesis of a new sulfonated tetramethyl carborhodamine fluorophore. When this carborhodamine is conjugated with an electron-rich, methoxy (-OMe) containing phenylenevinylene molecular wire, the resulting molecule, CRhOMe, is a voltage-sensitive fluorophore with red/far-red fluorescence. Using CRhOMe, changes in cellular membrane potential can be read out using fluorescence intensity or lifetime. In fluorescence intensity mode, CRhOMe tracks fast-spiking neuronal action potentials with greater signal-to-noise than state-of-the-art BeRST (another voltage-sensitive fluorophore). CRhOMe can also measure values of membrane potential. The fluorescence lifetime of CRhOMe follows a single exponential decay, substantially improving the quantification of membrane potential values using fluorescence lifetime imaging microscopy (FLIM). The combination of red-shifted excitation and emission, mono-exponential decay, and high voltage sensitivity enable fast FLIM recording of action potentials in cardiomyocytes. The ability to both monitor and measure membrane potentials with red light using CRhOMe makes it an important approach for studying biological voltages.
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Affiliation(s)
| | | | - Gloria Ortiz
- Department of Chemistry, University of California, Berkeley
| | | | | | - Evan W Miller
- Department of Chemistry, University of California, Berkeley
- Department of Molecular & Cell Biology, University of California, Berkeley
- Helen Wills Neuroscience Institute, University of California, Berkeley
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8
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Hanč P, Gonzalez RJ, Mazo IB, Wang Y, Lambert T, Ortiz G, Miller EW, von Andrian UH. Multimodal control of dendritic cell functions by nociceptors. Science 2023; 379:eabm5658. [PMID: 36996219 PMCID: PMC10642951 DOI: 10.1126/science.abm5658] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 02/17/2023] [Indexed: 04/01/2023]
Abstract
It is known that interactions between nociceptors and dendritic cells (DCs) can modulate immune responses in barrier tissues. However, our understanding of the underlying communication frameworks remains rudimentary. Here, we show that nociceptors control DCs in three molecularly distinct ways. First, nociceptors release the calcitonin gene-related peptide that imparts a distinct transcriptional profile on steady-state DCs characterized by expression of pro-interleukin-1β and other genes implicated in DC sentinel functions. Second, nociceptor activation induces contact-dependent calcium fluxes and membrane depolarization in DCs and enhances their production of proinflammatory cytokines when stimulated. Finally, nociceptor-derived chemokine CCL2 contributes to the orchestration of DC-dependent local inflammation and the induction of adaptive responses against skin-acquired antigens. Thus, the combined actions of nociceptor-derived chemokines, neuropeptides, and electrical activity fine-tune DC responses in barrier tissues.
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Affiliation(s)
- Pavel Hanč
- Department of Immunology, Harvard Medical School, Boston, MA 02115, USA
- The Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Rodrigo J Gonzalez
- Department of Immunology, Harvard Medical School, Boston, MA 02115, USA
- The Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Irina B Mazo
- Department of Immunology, Harvard Medical School, Boston, MA 02115, USA
- The Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Yidi Wang
- Department of Immunology, Harvard Medical School, Boston, MA 02115, USA
- The Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Talley Lambert
- Cell Biology Microscopy Facility, Harvard Medical School, Boston, MA 02115, USA
| | - Gloria Ortiz
- Departments of Chemistry, Molecular & Cell Biology, and Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Evan W Miller
- Departments of Chemistry, Molecular & Cell Biology, and Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Ulrich H von Andrian
- Department of Immunology, Harvard Medical School, Boston, MA 02115, USA
- The Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
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9
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Kirk MJ, Gold A, Ravi A, Sterne GR, Scott K, Miller EW. Cell-Surface Targeting of Fluorophores in Drosophila for Rapid Neuroanatomy Visualization. ACS Chem Neurosci 2023; 14:909-916. [PMID: 36799505 PMCID: PMC10187464 DOI: 10.1021/acschemneuro.2c00745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
Visualizing neuronal anatomy often requires labor-intensive immunohistochemistry on fixed and dissected brains. To facilitate rapid anatomical staining in live brains, we used genetically targeted membrane tethers that covalently link fluorescent dyes for in vivo neuronal labeling. We generated a series of extracellularly trafficked small-molecule tethering proteins, HaloTag-CD4 (Kirk et al. Front. Neurosci. 2021, 15, 754027) and SNAPf-CD4, which directly label transgene-expressing cells with commercially available ligand-substituted fluorescent dyes. We created stable transgenic Drosophila reporter lines, which express extracellular HaloTag-CD4 and SNAPf-CD4 with LexA and Gal4 drivers. Expressing these enzymes in live Drosophila brains, we labeled the expression patterns of various Gal4 driver lines recapitulating histological staining in live-brain tissues. Pan-neural expression of SNAPf-CD4 enabled the registration of live brains to an existing template for anatomical comparisons. We predict that these extracellular platforms will not only become a valuable complement to existing anatomical methods but will also prove useful for future genetic targeting of other small-molecule probes, drugs, and actuators.
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Affiliation(s)
- Molly J. Kirk
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Arya Gold
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Ashvin Ravi
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Gabriella R. Sterne
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, USA
| | - Kristin Scott
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, USA
| | - Evan W. Miller
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, USA
- Department of Chemistry, University of California, Berkeley, California 94720, USA
- Helen Wills Neuroscience Institute. University of California, Berkeley, California 94720, USA
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10
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Roy D, Michalet X, Bharadwaj K, Miller EW, Wang Y, Deb A, Wayne MA, Bruschini C, Charbon E, Vakili M, Gunsalus R, Clubb RT, Weiss S. Towards precise optical measurements of steady state of and small changes in resting membrane potentials. Biophys J 2023; 122:176a. [PMID: 36782833 DOI: 10.1016/j.bpj.2022.11.1096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Debjit Roy
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Xavier Michalet
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Kiran Bharadwaj
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Evan W Miller
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Yijie Wang
- Department of Medicine and Molecular Cell and Developmental Biology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Arjun Deb
- Department of Medicine and Molecular Cell and Developmental Biology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Michael A Wayne
- School of Engineering, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland
| | - Claudio Bruschini
- School of Engineering, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland
| | - Edoardo Charbon
- School of Engineering, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland
| | - Mahbanoo Vakili
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Robert Gunsalus
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, CA, USA
| | - Robert T Clubb
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
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11
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Raliski BK, Mun DM, Miller EW. Sulfone Rhodamines for Voltage Imaging. Chem Asian J 2022; 17:e202200906. [PMID: 36356288 PMCID: PMC9772261 DOI: 10.1002/asia.202200906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/11/2022] [Indexed: 11/12/2022]
Abstract
Fluorescent indicators that respond to changes in biological membrane potentials provide a powerful complement to existing methods for monitoring neuronal activity. Indicators that absorb and emit in the near infrared window are especially attractive, since lower energy wavelengths excite fewer biological molecules and can penetrate more deeply into biological tissues. In this work, we incorporate sulfone rhodamine chromophores into a voltage-sensitive scaffold in order to generate voltage sensitive fluorophores which absorb and emit above 700 nm. These Sulfone Rhodamine Voltage Reporters (SuRhoVRs) partition into cell membranes and display good sensitivity to membrane potential changes. The most sensitive SuRhoVR derivative also displays excellent photostability and can track membrane potential changes in dissociated rat hippocampal neurons.
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Affiliation(s)
- Benjamin K. Raliski
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-1460, USA
| | - Dong Min Mun
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-1460, USA
| | - Evan W. Miller
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-1460, USA,Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA 94720-1460, USA,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720-1460, USA
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12
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Klier PEZ, Roo R, Miller EW. Fluorescent indicators for imaging membrane potential of organelles. Curr Opin Chem Biol 2022; 71:102203. [PMID: 36084425 PMCID: PMC10259174 DOI: 10.1016/j.cbpa.2022.102203] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 07/18/2022] [Accepted: 07/21/2022] [Indexed: 01/27/2023]
Abstract
Plasma membrane potential is a key driver of the physiology of excitable cells like neurons and cardiomyocytes. Voltage-sensitive fluorescent indicators offer a powerful complement to traditional electrode-based approaches to measuring and monitoring membrane potential. Intracellular organelles can also generate membrane potential, yet the electrode- and fluorescent indicator-based approaches used for plasma membrane potential imaging are difficult to implement on intact organelles in their native environment. Here, we survey recent advances in developing and deploying voltage-sensitive fluorescent indicators to interrogate organelle membrane potential in intact cells.
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Affiliation(s)
- Pavel E Z Klier
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Ryan Roo
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA; Department of Molecular & Cell Biology, University of California, Berkeley, CA, 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA.
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13
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Abstract
Photoacoustic (PA) imaging is a powerful biomedical imaging modality. We designed KeTMR and KeJuR, two xanthene-based dyes that were readily obtained through a 2-step synthetic route. KeJuR has low molecular weight, good aqueous solubility, and superior chemical stability compared to KeTMR. KeJuR shows a robust PA signal under 860 nm excitation and can be paired with traditional PA dyes for multiplex imaging in blood samples under a tissue-mimicking environment.
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Affiliation(s)
- Xinqi Zhou
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA.
| | - Yuan Fang
- Department of Chemistry, University of Virginia, Charlottesville, VA, 22904, USA
| | - Viranga Wimalasiri
- Department of Chemistry, University of Virginia, Charlottesville, VA, 22904, USA
| | - Cliff I Stains
- Department of Chemistry, University of Virginia, Charlottesville, VA, 22904, USA
- University of Virgnia Cancer Center, University of Virginia, Charlottesville, VA, 22904, USA
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA.
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA
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14
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McCann JT, Benlian BR, Yaeger-Weiss SK, Knudson IJ, He M, Miller EW. Flipping the Switch: Reverse-Demand Voltage-Sensitive Fluorophores. J Am Chem Soc 2022; 144:13050-13054. [PMID: 35834763 PMCID: PMC9462387 DOI: 10.1021/jacs.2c05385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluorescence microscopy with fluorescent reporters that respond to environmental cues is a powerful method for interrogating biochemistry and biophysics in living systems. Photoinduced electron transfer (PeT) is commonly used as a trigger to modulate fluorescence in response to changes in the biological environment. PeT-based indicators rely on PeT either into the excited state (acceptor PeT) or out of the excited state (donor PeT). Our group has been developing voltage-sensitive fluorophores (VF dyes) that respond to changes in biological membrane potential (Vm). We hypothesize that the mechanism of voltage sensitivity arises from acceptor PeT (a-PeT) from an electron-rich aniline-containing molecular wire into the excited-state fluorophore, resulting in decreased fluorescence at negative Vm. In this work, we reversed the direction of electron flow to access donor-excited PeT (d-PeT) VF dyes by introducing electron-withdrawing rather than electron-rich molecular wires. VF dyes containing electron-withdrawing groups show voltage-sensitive fluorescence, but with the opposite polarity: hyperpolarizing Vm now gives fluorescence increases. We used a combination of computation and experiment to design and synthesize five d-PeT VF targets, two of which are voltage-sensitive.
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15
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Klier PEZ, Gest AMM, Martin JG, Roo R, Navarro MX, Lesiak L, Deal PE, Dadina N, Tyson J, Schepartz A, Miller EW. Bioorthogonal, Fluorogenic Targeting of Voltage-Sensitive Fluorophores for Visualizing Membrane Potential Dynamics in Cellular Organelles. J Am Chem Soc 2022; 144:12138-12146. [PMID: 35776693 DOI: 10.1021/jacs.2c02664] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Electrical potential differences across lipid bilayers play foundational roles in cellular physiology. Plasma membrane voltage is the most widely studied; however, the bilayers of organelles like mitochondria, lysosomes, nuclei, and the endoplasmic reticulum (ER) also provide opportunities for ionic compartmentalization and the generation of transmembrane potentials. Unlike plasma membranes, organellar bilayers, cloistered within the cell, remain recalcitrant to traditional approaches like patch-clamp electrophysiology. To address the challenge of monitoring changes in organelle membrane potential, we describe the design, synthesis, and application of the LUnAR RhoVR (Ligation Unquenched for Activation and Redistribution Rhodamine-based Voltage Reporter) for optically monitoring membrane potential changes in the ER of living cells. We pair a tetrazine-quenched RhoVR for voltage sensing with a transcyclooctene (TCO)-conjugated ceramide (Cer-TCO) for targeting to the ER. Bright fluorescence is observed only at the coincidence of the LUnAR RhoVR and TCO in the ER, minimizing non-specific, off-target fluorescence. We show that the product of the LUnAR RhoVR and Cer-TCO is voltage-sensitive and that the LUnAR RhoVR can be targeted to an intact ER in living cells. Using the LUnAR RhoVR, we use two-color, ER-localized, fast voltage imaging coupled with cytosolic Ca2+ imaging to validate the electroneutrality of Ca2+ release from internal stores. Finally, we use the LUnAR RhoVR to directly visualize functional coupling between the plasma-ER membranes in patch clamped cell lines, providing the first direct evidence of the sign of the ER potential response to plasma membrane potential changes. We envision that the LUnAR RhoVR, along with other existing organelle-targeting TCO probes, could be applied widely for exploring organelle physiology.
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Affiliation(s)
- Pavel E Z Klier
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Anneliese M M Gest
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Julia G Martin
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Ryan Roo
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Marisol X Navarro
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Lauren Lesiak
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Parker E Deal
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Neville Dadina
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Jonathan Tyson
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Alanna Schepartz
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
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16
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Yudovich S, Marzouqe A, Kantorovitsch J, Teblum E, Chen T, Enderlein J, Miller EW, Weiss S. Electrically Controlling and Optically Observing the Membrane Potential of Supported Lipid Bilayers. Biophys J 2022; 121:2624-2637. [PMID: 35619563 DOI: 10.1016/j.bpj.2022.05.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 04/26/2022] [Accepted: 05/23/2022] [Indexed: 11/02/2022] Open
Abstract
Supported lipid bilayers are a well-developed model system for the study of membranes and their associated proteins, such as membrane channels, enzymes, and receptors. These versatile model membranes can be made from various components, ranging from simple synthetic phospholipids to complex mixtures of constituents, mimicking the cell membrane with its relevant physiochemical and molecular phenomena. In addition, the high stability of supported lipid bilayers allows for their study via a wide array of experimental probes. In this work, we describe a platform for supported lipid bilayers that is accessible both electrically and optically, and demonstrate direct optical observation of the transmembrane potential of supported lipid bilayers. We show that the polarization of the supported membrane can be electrically controlled and optically probed using voltage-sensitive dyes. Membrane polarization dynamics is understood through electrochemical impedance spectroscopy and the analysis of an equivalent electrical circuit model. In addition, we describe the effect of the conducting electrode layer on the fluorescence of the optical probe through metal-induced energy transfer, and show that while this energy transfer has an adverse effect on the voltage sensitivity of the fluorescent probe, its strong distance dependency allows for axial localization of fluorescent emitters with ultrahigh accuracy. We conclude with a discussion on possible applications of this platform for the study of voltage-dependent membrane proteins and other processes in membrane biology and surface science.
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Affiliation(s)
- Shimon Yudovich
- Department of Physics, Bar-Ilan University, Ramat-Gan, 52900, Israel; Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel.
| | - Adan Marzouqe
- Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel; Department of Chemistry, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Joseph Kantorovitsch
- Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Eti Teblum
- Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Tao Chen
- Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany
| | - Jörg Enderlein
- Third Institute of Physics-Biophysics, Georg August University, 37077 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Georg August University, Germany
| | - Evan W Miller
- Departments of Chemistry, Molecular & Cell Biology, and Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
| | - Shimon Weiss
- Department of Physics, Bar-Ilan University, Ramat-Gan, 52900, Israel; Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel; Departments of Chemistry and Biochemistry, Physiology, and California NanoSystems Institute, University of California Los Angeles, Los Angeles, CA 90095.
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17
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Kramer RH, Miller EW, Abdelfattah A, Baker B. Fluorescent Reporters for Sensing Membrane Potential: Tools for Bioelectricity. Bioelectricity 2022. [DOI: 10.1089/bioe.2022.0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Richard H. Kramer
- Department of Molecular & Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
| | - Evan W. Miller
- Departments of Chemistry and Molecular & Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
| | - Ahmed Abdelfattah
- Department of Neuroscience, Brown University, Providence, Rhode Island, USA
| | - Bradley Baker
- Brain Science Institute, Korea Institute of Science and Technology, Seoul, South Korea
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18
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Roy D, Michalet X, Miller EW, Gunsalus RP, Clubb RT, Weiss S. Bacterial resting membrane potential: a case study with Bacillus subtilis. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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19
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Moreno JD, Bhagavan D, Li A, Gerstner NC, Miller EW, Huebsch N, Cresci S, Silva JR. Pulsus Alternans in Cardiogenic Shock Recapitulated in Single Cell Fluorescence Imaging of a Patient's Cardiomyocyte. Circ Heart Fail 2022; 15:e008855. [PMID: 34886677 PMCID: PMC8847329 DOI: 10.1161/circheartfailure.121.008855] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Jonathan D. Moreno
- Division of Cardiology, Department of Medicine, Washington University in St. Louis
| | - Druv Bhagavan
- Department of Biomedical Engineering, Washington University in St. Louis
| | - Allie Li
- Division of Cardiology, Department of Medicine, Washington University in St. Louis
| | - Nels C. Gerstner
- Departments of Chemistry and Molecular & Cell Biology, University of California, Berkeley
| | - Evan W. Miller
- Departments of Chemistry and Molecular & Cell Biology, University of California, Berkeley
| | - Nathaniel Huebsch
- Department of Biomedical Engineering, Washington University in St. Louis
| | - Sharon Cresci
- Division of Cardiology, Department of Medicine, Washington University in St. Louis,Correspondence: Sharon Cresci, MD, 660 South Euclid Avenue, Box 8086, St. Louis, MO, 63130, Phone: 314-362-5363, Fax: 314-747-4758,
| | - Jonathan R. Silva
- Department of Biomedical Engineering, Washington University in St. Louis,Jonathan R. Silva, PhD, One Brookings Drive, Whitaker Hall, Room 290G, Saint Louis, Missouri, 63130, United States. Phone number: 314-935-8837,
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20
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Grenier V, Martinez KN, Benlian BR, García-Almedina DM, Raliski BK, Boggess SC, Maza JC, Yang SJ, Gest AMM, Miller EW. Molecular Prosthetics for Long-Term Functional Imaging with Fluorescent Reporters. ACS Cent Sci 2022; 8:118-121. [PMID: 35111902 PMCID: PMC8802189 DOI: 10.1021/acscentsci.1c01153] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Indexed: 06/14/2023]
Abstract
Voltage-sensitive fluorescent reporters can reveal fast changes in the membrane potential in neurons and cardiomyocytes. However, in many cases, illumination in the presence of the fluorescent reporters results in disruptions to the action potential shape that limits the length of recording sessions. We show here that a molecular prosthetic approach, previously limited to fluorophores, rather than indicators, can be used to substantially prolong imaging in neurons and cardiomyocytes.
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Affiliation(s)
- Vincent Grenier
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
| | - Kayli N. Martinez
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
| | - Brittany R. Benlian
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
| | - Derek M. García-Almedina
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
| | - Benjamin K. Raliski
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
| | - Steven C. Boggess
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
| | - Johnathan C. Maza
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
| | - Samantha J. Yang
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
| | - Anneliese M. M. Gest
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
| | - Evan W. Miller
- Department
of Chemistry and Department of Molecular and Cell Biology and Helen Wills Neuroscience
Institute. University of California, Berkeley, California 94720, United States
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21
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Abdelfattah AS, Ahuja S, Akkin T, Allu SR, Brake J, Boas DA, Buckley EM, Campbell RE, Chen AI, Cheng X, Čižmár T, Costantini I, De Vittorio M, Devor A, Doran PR, El Khatib M, Emiliani V, Fomin-Thunemann N, Fainman Y, Fernandez-Alfonso T, Ferri CGL, Gilad A, Han X, Harris A, Hillman EMC, Hochgeschwender U, Holt MG, Ji N, Kılıç K, Lake EMR, Li L, Li T, Mächler P, Miller EW, Mesquita RC, Nadella KMNS, Nägerl UV, Nasu Y, Nimmerjahn A, Ondráčková P, Pavone FS, Perez Campos C, Peterka DS, Pisano F, Pisanello F, Puppo F, Sabatini BL, Sadegh S, Sakadzic S, Shoham S, Shroff SN, Silver RA, Sims RR, Smith SL, Srinivasan VJ, Thunemann M, Tian L, Tian L, Troxler T, Valera A, Vaziri A, Vinogradov SA, Vitale F, Wang LV, Uhlířová H, Xu C, Yang C, Yang MH, Yellen G, Yizhar O, Zhao Y. Neurophotonic tools for microscopic measurements and manipulation: status report. Neurophotonics 2022; 9:013001. [PMID: 35493335 PMCID: PMC9047450 DOI: 10.1117/1.nph.9.s1.013001] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Neurophotonics was launched in 2014 coinciding with the launch of the BRAIN Initiative focused on development of technologies for advancement of neuroscience. For the last seven years, Neurophotonics' agenda has been well aligned with this focus on neurotechnologies featuring new optical methods and tools applicable to brain studies. While the BRAIN Initiative 2.0 is pivoting towards applications of these novel tools in the quest to understand the brain, this status report reviews an extensive and diverse toolkit of novel methods to explore brain function that have emerged from the BRAIN Initiative and related large-scale efforts for measurement and manipulation of brain structure and function. Here, we focus on neurophotonic tools mostly applicable to animal studies. A companion report, scheduled to appear later this year, will cover diffuse optical imaging methods applicable to noninvasive human studies. For each domain, we outline the current state-of-the-art of the respective technologies, identify the areas where innovation is needed, and provide an outlook for the future directions.
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Affiliation(s)
- Ahmed S. Abdelfattah
- Brown University, Department of Neuroscience, Providence, Rhode Island, United States
| | - Sapna Ahuja
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Taner Akkin
- University of Minnesota, Department of Biomedical Engineering, Minneapolis, Minnesota, United States
| | - Srinivasa Rao Allu
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Joshua Brake
- Harvey Mudd College, Department of Engineering, Claremont, California, United States
| | - David A. Boas
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Erin M. Buckley
- Georgia Institute of Technology and Emory University, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
- Emory University, Department of Pediatrics, Atlanta, Georgia, United States
| | - Robert E. Campbell
- University of Tokyo, Department of Chemistry, Tokyo, Japan
- University of Alberta, Department of Chemistry, Edmonton, Alberta, Canada
| | - Anderson I. Chen
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Xiaojun Cheng
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Tomáš Čižmár
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Irene Costantini
- University of Florence, European Laboratory for Non-Linear Spectroscopy, Department of Biology, Florence, Italy
- National Institute of Optics, National Research Council, Rome, Italy
| | - Massimo De Vittorio
- Istituto Italiano di Tecnologia, Center for Biomolecular Nanotechnologies, Arnesano, Italy
| | - Anna Devor
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Patrick R. Doran
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Mirna El Khatib
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | | | - Natalie Fomin-Thunemann
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Yeshaiahu Fainman
- University of California San Diego, Department of Electrical and Computer Engineering, La Jolla, California, United States
| | - Tomas Fernandez-Alfonso
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - Christopher G. L. Ferri
- University of California San Diego, Departments of Neurosciences, La Jolla, California, United States
| | - Ariel Gilad
- The Hebrew University of Jerusalem, Institute for Medical Research Israel–Canada, Department of Medical Neurobiology, Faculty of Medicine, Jerusalem, Israel
| | - Xue Han
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Andrew Harris
- Weizmann Institute of Science, Department of Brain Sciences, Rehovot, Israel
| | | | - Ute Hochgeschwender
- Central Michigan University, Department of Neuroscience, Mount Pleasant, Michigan, United States
| | - Matthew G. Holt
- University of Porto, Instituto de Investigação e Inovação em Saúde (i3S), Porto, Portugal
| | - Na Ji
- University of California Berkeley, Department of Physics, Berkeley, California, United States
| | - Kıvılcım Kılıç
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Evelyn M. R. Lake
- Yale School of Medicine, Department of Radiology and Biomedical Imaging, New Haven, Connecticut, United States
| | - Lei Li
- California Institute of Technology, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, Pasadena, California, United States
| | - Tianqi Li
- University of Minnesota, Department of Biomedical Engineering, Minneapolis, Minnesota, United States
| | - Philipp Mächler
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Evan W. Miller
- University of California Berkeley, Departments of Chemistry and Molecular & Cell Biology and Helen Wills Neuroscience Institute, Berkeley, California, United States
| | | | | | - U. Valentin Nägerl
- Interdisciplinary Institute for Neuroscience University of Bordeaux & CNRS, Bordeaux, France
| | - Yusuke Nasu
- University of Tokyo, Department of Chemistry, Tokyo, Japan
| | - Axel Nimmerjahn
- Salk Institute for Biological Studies, Waitt Advanced Biophotonics Center, La Jolla, California, United States
| | - Petra Ondráčková
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Francesco S. Pavone
- National Institute of Optics, National Research Council, Rome, Italy
- University of Florence, European Laboratory for Non-Linear Spectroscopy, Department of Physics, Florence, Italy
| | - Citlali Perez Campos
- Columbia University, Zuckerman Mind Brain Behavior Institute, New York, United States
| | - Darcy S. Peterka
- Columbia University, Zuckerman Mind Brain Behavior Institute, New York, United States
| | - Filippo Pisano
- Istituto Italiano di Tecnologia, Center for Biomolecular Nanotechnologies, Arnesano, Italy
| | - Ferruccio Pisanello
- Istituto Italiano di Tecnologia, Center for Biomolecular Nanotechnologies, Arnesano, Italy
| | - Francesca Puppo
- University of California San Diego, Departments of Neurosciences, La Jolla, California, United States
| | - Bernardo L. Sabatini
- Harvard Medical School, Howard Hughes Medical Institute, Department of Neurobiology, Boston, Massachusetts, United States
| | - Sanaz Sadegh
- University of California San Diego, Departments of Neurosciences, La Jolla, California, United States
| | - Sava Sakadzic
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Shy Shoham
- New York University Grossman School of Medicine, Tech4Health and Neuroscience Institutes, New York, New York, United States
| | - Sanaya N. Shroff
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - R. Angus Silver
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - Ruth R. Sims
- Sorbonne University, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Spencer L. Smith
- University of California Santa Barbara, Department of Electrical and Computer Engineering, Santa Barbara, California, United States
| | - Vivek J. Srinivasan
- New York University Langone Health, Departments of Ophthalmology and Radiology, New York, New York, United States
| | - Martin Thunemann
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Lei Tian
- Boston University, Departments of Electrical Engineering and Biomedical Engineering, Boston, Massachusetts, United States
| | - Lin Tian
- University of California Davis, Department of Biochemistry and Molecular Medicine, Davis, California, United States
| | - Thomas Troxler
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Antoine Valera
- University College London, Department of Neuroscience, Physiology and Pharmacology, London, United Kingdom
| | - Alipasha Vaziri
- Rockefeller University, Laboratory of Neurotechnology and Biophysics, New York, New York, United States
- The Rockefeller University, The Kavli Neural Systems Institute, New York, New York, United States
| | - Sergei A. Vinogradov
- University of Pennsylvania, Perelman School of Medicine, Department of Biochemistry and Biophysics, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, School of Arts and Sciences, Department of Chemistry, Philadelphia, Pennsylvania, United States
| | - Flavia Vitale
- Center for Neuroengineering and Therapeutics, Departments of Neurology, Bioengineering, Physical Medicine and Rehabilitation, Philadelphia, Pennsylvania, United States
| | - Lihong V. Wang
- California Institute of Technology, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, Pasadena, California, United States
| | - Hana Uhlířová
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Chris Xu
- Cornell University, School of Applied and Engineering Physics, Ithaca, New York, United States
| | - Changhuei Yang
- California Institute of Technology, Departments of Electrical Engineering, Bioengineering and Medical Engineering, Pasadena, California, United States
| | - Mu-Han Yang
- University of California San Diego, Department of Electrical and Computer Engineering, La Jolla, California, United States
| | - Gary Yellen
- Harvard Medical School, Department of Neurobiology, Boston, Massachusetts, United States
| | - Ofer Yizhar
- Weizmann Institute of Science, Department of Brain Sciences, Rehovot, Israel
| | - Yongxin Zhao
- Carnegie Mellon University, Department of Biological Sciences, Pittsburgh, Pennsylvania, United States
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22
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Kierzek M, Deal PE, Miller EW, Mukherjee S, Wachten D, Baumann A, Kaupp UB, Strünker T, Brenker C. Simultaneous recording of multiple cellular signaling events by frequency- and spectrally-tuned multiplexing of fluorescent probes. eLife 2021; 10:e63129. [PMID: 34859780 PMCID: PMC8700268 DOI: 10.7554/elife.63129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 12/01/2021] [Indexed: 12/21/2022] Open
Abstract
Fluorescent probes that change their spectral properties upon binding to small biomolecules, ions, or changes in the membrane potential (Vm) are invaluable tools to study cellular signaling pathways. Here, we introduce a novel technique for simultaneous recording of multiple probes at millisecond time resolution: frequency- and spectrally-tuned multiplexing (FASTM). Different from present multiplexing approaches, FASTM uses phase-sensitive signal detection, which renders various combinations of common probes for Vm and ions accessible for multiplexing. Using kinetic stopped-flow fluorimetry, we show that FASTM allows simultaneous recording of rapid changes in Ca2+, pH, Na+, and Vm with high sensitivity and minimal crosstalk. FASTM is also suited for multiplexing using single-cell microscopy and genetically encoded FRET biosensors. Moreover, FASTM is compatible with optochemical tools to study signaling using light. Finally, we show that the exceptional time resolution of FASTM also allows resolving rapid chemical reactions. Altogether, FASTM opens new opportunities for interrogating cellular signaling.
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Affiliation(s)
- Michelina Kierzek
- Centre of Reproductive Medicine and Andrology, University of MünsterMünsterGermany
- CiM-IMPRS Graduate School, University of MünsterMünsterGermany
| | - Parker E Deal
- Department of Chemistry, University of California, BerkeleyBerkeleyUnited States
| | - Evan W Miller
- Department of Chemistry, University of California, BerkeleyBerkeleyUnited States
- Department of Molecular & Cell Biology, University of California, BerkeleyBerkeleyUnited States
- Helen Wills Neuroscience Institute, University of California, BerkeleyBerkeleyUnited States
| | - Shatanik Mukherjee
- Molecular Sensory Systems, Center of Advanced European Studies and ResearchBonnGermany
| | - Dagmar Wachten
- Institute of Innate Immunity, Department of Biophysical Imaging, Medical Faculty, University of BonnBonnGermany
| | - Arnd Baumann
- Institute of Biological Information Processing (IBI-1), Research Center JülichJülichGermany
| | - U Benjamin Kaupp
- Life & Medical Sciences Institute (LIMES), University of BonnBonnGermany
| | - Timo Strünker
- Centre of Reproductive Medicine and Andrology, University of MünsterMünsterGermany
- Cells in Motion Interfaculty Centre, University of MünsterMünsterGermany
| | - Christoph Brenker
- Centre of Reproductive Medicine and Andrology, University of MünsterMünsterGermany
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23
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Ortiz G, Liu P, Deal PE, Nensel AK, Martinez KN, Shamardani K, Adesnik H, Miller EW. A silicon-rhodamine chemical-genetic hybrid for far red voltage imaging from defined neurons in brain slice. RSC Chem Biol 2021; 2:1594-1599. [PMID: 34977574 PMCID: PMC8637932 DOI: 10.1039/d1cb00156f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/27/2021] [Indexed: 02/06/2023] Open
Abstract
We describe the design, synthesis, and application of voltage-sensitive silicon rhodamines. Based on the Berkeley Red Sensor of Transmembrane potential, or BeRST, scaffold, the new dyes possess an isomeric molecular wire for improved alignment in the plasma membrane and 2′ carboxylic acids for ready functionalization. The new isoBeRST dyes have a voltage sensitivity of 24% ΔF/F per 100 mV. Combined with a flexible polyethyleneglycol (PEG) linker and a chloroalkane HaloTag ligand, isoBeRST dyes enable voltage imaging from genetically defined cells and neurons and provide improved labeling over previous, rhodamine-based hybrid strategies. isoBeRST-Halo hybrid indicators achieve single-trial voltage imaging of membrane potential dynamics from cultured hippocampal neurons or cortical neurons in brain slices. With far-red/near infrared excitation and emission, turn-on response to action potentials, and effective cell labeling in thick tissue, the new isoBeRST-Halo derivatives provide an important complement to voltage imaging in neurobiology. Small-molecule enzyme hybrids pair a far-red voltage-sensitive fluorophore with a cell-surface expressed HaloTag enzyme via a flexible linker to enable voltage imaging from genetically defined neurons in culture and brain slice.![]()
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Affiliation(s)
- Gloria Ortiz
- Department of Chemistry, University of California Berkeley California 94720-1460 USA
| | - Pei Liu
- Department of Chemistry, University of California Berkeley California 94720-1460 USA
| | - Parker E Deal
- Department of Chemistry, University of California Berkeley California 94720-1460 USA
| | - Ashley K Nensel
- Department of Chemistry, University of California Berkeley California 94720-1460 USA
| | - Kayli N Martinez
- Department of Chemistry, University of California Berkeley California 94720-1460 USA
| | - Kiarash Shamardani
- Department of Molecular & Cell Biology, University of California Berkeley California 94720-1460 USA
| | - Hillel Adesnik
- Department of Molecular & Cell Biology, University of California Berkeley California 94720-1460 USA.,Helen Wills Neuroscience Institute, University of California Berkeley California 94720-1460 USA
| | - Evan W Miller
- Department of Chemistry, University of California Berkeley California 94720-1460 USA .,Department of Molecular & Cell Biology, University of California Berkeley California 94720-1460 USA.,Helen Wills Neuroscience Institute, University of California Berkeley California 94720-1460 USA
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24
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Kirk MJ, Benlian BR, Han Y, Gold A, Ravi A, Deal PE, Molina RS, Drobizhev M, Dickman D, Scott K, Miller EW. Voltage Imaging in Drosophila Using a Hybrid Chemical-Genetic Rhodamine Voltage Reporter. Front Neurosci 2021; 15:754027. [PMID: 34867164 PMCID: PMC8637050 DOI: 10.3389/fnins.2021.754027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/15/2021] [Indexed: 12/03/2022] Open
Abstract
We combine a chemically-synthesized, voltage-sensitive fluorophore with a genetically encoded, self-labeling enzyme to enable voltage imaging in Drosophila melanogaster. Previously, we showed that a rhodamine voltage reporter (RhoVR) combined with the HaloTag self-labeling enzyme could be used to monitor membrane potential changes from mammalian neurons in culture and brain slice. Here, we apply this hybrid RhoVR-Halo approach in vivo to achieve selective neuron labeling in intact fly brains. We generate a Drosophila UAS-HaloTag reporter line in which the HaloTag enzyme is expressed on the surface of cells. We validate the voltage sensitivity of this new construct in cell culture before driving expression of HaloTag in specific brain neurons in flies. We show that selective labeling of synapses, cells, and brain regions can be achieved with RhoVR-Halo in either larval neuromuscular junction (NMJ) or in whole adult brains. Finally, we validate the voltage sensitivity of RhoVR-Halo in fly tissue via dual-electrode/imaging at the NMJ, show the efficacy of this approach for measuring synaptic excitatory post-synaptic potentials (EPSPs) in muscle cells, and perform voltage imaging of carbachol-evoked depolarization and osmolarity-evoked hyperpolarization in projection neurons and in interoceptive subesophageal zone neurons in fly brain explants following in vivo labeling. We envision the turn-on response to depolarizations, fast response kinetics, and two-photon compatibility of chemical indicators, coupled with the cellular and synaptic specificity of genetically-encoded enzymes, will make RhoVR-Halo a powerful complement to neurobiological imaging in Drosophila.
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Affiliation(s)
- Molly J. Kirk
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Brittany R. Benlian
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Yifu Han
- Department of Neurobiology, University of Southern California, Los Angeles, CA, United States
| | - Arya Gold
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Ashvin Ravi
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Parker E. Deal
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Rosana S. Molina
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Mikhail Drobizhev
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA, United States
| | - Kristin Scott
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Evan W. Miller
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
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25
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Lazzari-Dean JR, Miller EW. Optical Estimation of Absolute Membrane Potential Using One- and Two-Photon Fluorescence Lifetime Imaging Microscopy. Bioelectricity 2021; 3:197-203. [PMID: 34734167 DOI: 10.1089/bioe.2021.0007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Background: Membrane potential (V mem) exerts physiological influence across a wide range of time and space scales. To study V mem in these diverse contexts, it is essential to accurately record absolute values of V mem, rather than solely relative measurements. Materials and Methods: We use fluorescence lifetime imaging of a small molecule voltage sensitive dye (VF2.1.Cl) to estimate mV values of absolute membrane potential. Results: We test the consistency of VF2.1.Cl lifetime measurements performed on different single-photon counting instruments and find that they are in striking agreement (differences of <0.5 ps/mV in the slope and <50 ps in the y-intercept). We also demonstrate that VF2.1.Cl lifetime reports absolute V mem under two-photon (2P) illumination with better than 20 mV of V mem resolution, a nearly 10-fold improvement over other lifetime-based methods. Conclusions: We demonstrate that VF-FLIM is a robust and portable metric for V mem across imaging platforms and under both one-photon and 2P illumination. This work is a critical foundation for application of VF-FLIM to record absolute membrane potential signals in thick tissue.
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Affiliation(s)
- Julia R Lazzari-Dean
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA.,Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, USA
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26
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Charrez B, Charwat V, Siemons BA, Goswami I, Sakolish C, Luo YS, Finsberg H, Edwards AG, Miller EW, Rusyn I, Healy KE. Heart Muscle Microphysiological System for Cardiac Liability Prediction of Repurposed COVID-19 Therapeutics. Front Pharmacol 2021; 12:684252. [PMID: 34421592 PMCID: PMC8378272 DOI: 10.3389/fphar.2021.684252] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 07/05/2021] [Indexed: 12/27/2022] Open
Abstract
Despite global efforts, it took 7 months between the proclamation of global SARS-CoV-2 pandemic and the first FDA-approved treatment for COVID-19. During this timeframe, clinicians focused their efforts on repurposing drugs, such as hydroxychloroquine (HCQ) or azithromycin (AZM) to treat hospitalized COVID-19 patients. While clinical trials are time-consuming, the exponential increase in hospitalizations compelled the FDA to grant an emergency use authorization for HCQ and AZM as treatment for COVID-19, although there was limited evidence of their combined efficacy and safety. The authorization was revoked 4 months later, giving rise to controversial political and scientific debates illustrating important challenges such as premature authorization of potentially ineffective or unsafe therapeutics, while diverting resources from screening of effective drugs. Here we report on a preclinical drug screening platform, a cardiac microphysiological system (MPS), to rapidly identify clinically relevant cardiac liabilities associated with HCQ and AZM. The cardiac MPS is a microfabricated fluidic system in which cardiomyocytes derived from human induced pluripotent stem cells self-arrange into a uniaxially beating tissue. The drug response was measured using outputs that correlate with clinical measurements such as action potential duration (proxy for clinical QT interval) and drug-biomarker pairing. The cardiac MPS predicted clinical arrhythmias associated with QT prolongation and rhythm instabilities in tissues treated with HCQ. We found no change in QT interval upon acute exposure to AZM, while still observing a significant increase in arrhythmic events. These results suggest that this MPS can not only predict arrhythmias, but it can also identify arrhythmias even when QT prolongation is absent. When exposed to HCQ and AZM polytherapy, this MPS faithfully reflected clinical findings, in that the combination of drugs synergistically increased QT interval when compared to single drug exposure, while not worsening the overall frequency of arrhythmic events. The high content cardiac MPS can rapidly evaluate the cardiac safety of potential therapeutics, ultimately accelerating patients' access to safe and effective treatments.
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Affiliation(s)
- Bérénice Charrez
- Department of Bioengineering and California Institute for Quantitative Biosciences (QB3), University of California at Berkeley, Berkeley, CA, United States
| | - Verena Charwat
- Department of Bioengineering and California Institute for Quantitative Biosciences (QB3), University of California at Berkeley, Berkeley, CA, United States
| | - Brian A. Siemons
- Department of Bioengineering and California Institute for Quantitative Biosciences (QB3), University of California at Berkeley, Berkeley, CA, United States
| | - Ishan Goswami
- Department of Bioengineering and California Institute for Quantitative Biosciences (QB3), University of California at Berkeley, Berkeley, CA, United States
| | - Courtney Sakolish
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | | | - Andrew G. Edwards
- Department of Pharmacology, School of Medicine, University of California at Davis, Davis, CA, United States
| | - Evan W. Miller
- Department of Chemistry, University of California at Berkeley, Berkeley, CA, United States
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, United States
- Helen Wills Neuroscience Institute, University of California at Berkeley, Berkeley, CA, United States
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Kevin E. Healy
- Department of Bioengineering and California Institute for Quantitative Biosciences (QB3), University of California at Berkeley, Berkeley, CA, United States
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, CA, United States
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27
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Boggess SC, Gandhi SS, Benlian BR, Miller EW. Vinyl-Fluorene Molecular Wires for Voltage Imaging with Enhanced Sensitivity and Reduced Phototoxicity. J Am Chem Soc 2021; 143:11903-11907. [PMID: 34323478 DOI: 10.1021/jacs.1c04543] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Fluorescent voltage indicators are an attractive alternative for studying the electrical activity of excitable cells; however, the development of indicators that are both highly sensitive and low in toxicity over long-term experiments remains a challenge. Previously, we reported a fluorene-based voltage-sensitive fluorophore that exhibits much lower phototoxicity than previous voltage indicators in cardiomyocyte monolayers, but suffers from low sensitivity to membrane potential changes. Here, we report that the addition of a single vinyl spacer in the fluorene molecular wire scaffold improves the voltage sensitivity 1.5- to 3.5-fold over fluorene-based voltage probes. Furthermore, we demonstrate the improved ability of the new vinyl-fluorene VoltageFluors to monitor action potential kinetics in both mammalian neurons and human-induced pluripotent stem cell-derived cardiomyocytes. Addition of the vinyl spacer between the aniline donor and fluorene monomer results in indicators that are significantly less phototoxic in cardiomyocyte monolayers. These results demonstrate how structural modification to the voltage sensing domain have a large effect on improving the overall properties of molecular wire-based voltage indicators.
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28
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Abstract
In 1980, Roger Tsien published a paper, in this journal [Tsien, R. Y. (1980) Biochemistry, 19 (11), 2396], titled "New calcium indicators and buffers with high selectivity against magnesium and protons: design, synthesis, and properties of prototype structures". These new buffers included 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, or BAPTA, which is still widely used today. And so, the world was set alight with new ways in which to visualize Ca2+. The ability to watch fluctuations in intracellular Ca2+ revolutionized the life sciences, although the fluorescent indicators used today, particularly in neurobiology, no longer rely exclusively on BAPTA but on genetically encoded fluorescent Ca2+ indicators. In this Perspective, we reflect on the origins of Ca2+ imaging with a special focus on the contributions made by Roger Tsien, from the early concept of selective Ca2+ binding described in Biochemistry to optical Ca2+ indicators based on chemically synthesized fluorophores to genetically encoded fluorescent Ca2+ indicators.
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29
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Raliski BK, Kirk MJ, Miller EW. Imaging Spontaneous Neuronal Activity with Voltage-Sensitive Dyes. Curr Protoc 2021; 1:e48. [PMID: 33760396 DOI: 10.1002/cpz1.48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Accurately mapping changes in cellular membrane potential across large groups of neurons is crucial for understanding the organization and maintenance of neural circuits. Measuring cellular voltage changes by optical means allows greater spatial resolution than traditional electrophysiology methods and is adaptable to high-throughput imaging experiments. VoltageFluors, a class of voltage-sensitive dyes, have recently been used to optically study the spontaneous activity of many neurons simultaneously in dissociated culture. VoltageFluors are particularly useful for experiments investigating differences in excitability and connectivity between neurons at different stages of development and in different disease models. The protocols in this article describe general procedures for preparing dissociated cultures, imaging spontaneous activity in dissociated cultures with VoltageFluors, and analyzing optical spontaneous activity data. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Preparation of dissociated rat hippocampal or cortical cultures Alternate Protocol: Preparation of microisland dissociated cultures Basic Protocol 2: Imaging of spontaneous activity in dissociated cultures using voltage-sensitive dyes Basic Protocol 3: Analysis of spontaneous activity imaging data.
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Affiliation(s)
- Benjamin K Raliski
- Department of Chemistry, University of California Berkeley, Berkeley, California
| | - Molly J Kirk
- Department of Molecular & Cell Biology, University of California Berkeley, Berkeley, California
| | - Evan W Miller
- Department of Chemistry, University of California Berkeley, Berkeley, California.,Department of Molecular & Cell Biology, University of California Berkeley, Berkeley, California.,Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California
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30
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Puppo F, Sadegh S, Trujillo CA, Thunemann M, Campbell EP, Vandenberghe M, Shan X, Akkouh IA, Miller EW, Bloodgood BL, Silva GA, Dale AM, Einevoll GT, Djurovic S, Andreassen OA, Muotri AR, Devor A. All-Optical Electrophysiology in hiPSC-Derived Neurons With Synthetic Voltage Sensors. Front Cell Neurosci 2021; 15:671549. [PMID: 34122014 PMCID: PMC8193062 DOI: 10.3389/fncel.2021.671549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/03/2021] [Indexed: 12/26/2022] Open
Abstract
Voltage imaging and “all-optical electrophysiology” in human induced pluripotent stem cell (hiPSC)-derived neurons have opened unprecedented opportunities for high-throughput phenotyping of activity in neurons possessing unique genetic backgrounds of individual patients. While prior all-optical electrophysiology studies relied on genetically encoded voltage indicators, here, we demonstrate an alternative protocol using a synthetic voltage sensor and genetically encoded optogenetic actuator that generate robust and reproducible results. We demonstrate the functionality of this method by measuring spontaneous and evoked activity in three independent hiPSC-derived neuronal cell lines with distinct genetic backgrounds.
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Affiliation(s)
- Francesca Puppo
- Department of Pediatrics/Rady Children's Hospital San Diego, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Sanaz Sadegh
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, United States
| | - Cleber A Trujillo
- Department of Pediatrics/Rady Children's Hospital San Diego, School of Medicine, University of California, San Diego, La Jolla, CA, United States.,Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Martin Thunemann
- Department of Biomedical Engineering, Boston University, Boston, MA, United States
| | - Evan P Campbell
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, CA, United States
| | - Matthieu Vandenberghe
- Division of Mental Health and Addiction, Oslo University Hospital, NORMENT, KG Jebsen Centre for Neurodevelopmental Disorders, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Xiwei Shan
- Department of Pediatrics/Rady Children's Hospital San Diego, School of Medicine, University of California, San Diego, La Jolla, CA, United States.,Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Ibrahim A Akkouh
- Division of Mental Health and Addiction, Oslo University Hospital, NORMENT, KG Jebsen Centre for Neurodevelopmental Disorders, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Evan W Miller
- Department of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Brenda L Bloodgood
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, La Jolla, CA, United States
| | - Gabriel A Silva
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States
| | - Anders M Dale
- Department of Radiology, University of California, San Diego, La Jolla, CA, United States
| | - Gaute T Einevoll
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway.,Department of Physics, University of Oslo, Oslo, Norway
| | - Srdjan Djurovic
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway.,NORMENT, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Ole A Andreassen
- Division of Mental Health and Addiction, Oslo University Hospital, NORMENT, KG Jebsen Centre for Neurodevelopmental Disorders, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Alysson R Muotri
- Department of Pediatrics/Rady Children's Hospital San Diego, School of Medicine, University of California, San Diego, La Jolla, CA, United States.,Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States.,Kavli Institute for Brain and Mind and Halıcıoglu Data Science Institute, University of California, San Diego, La Jolla, CA, United States.,Center for Academic Research and Training in Anthropogeny (CARTA), La Jolla, CA, United States
| | - Anna Devor
- Department of Biomedical Engineering, Boston University, Boston, MA, United States.,Department of Radiology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States
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31
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Benlian BR, Klier PEZ, Martinez KN, Schwinn MK, Kirkland TA, Miller EW. Small Molecule-Protein Hybrid for Voltage Imaging via Quenching of Bioluminescence. ACS Sens 2021; 6:1857-1863. [PMID: 33723996 DOI: 10.1021/acssensors.1c00058] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We report a small-molecule enzyme pair for optical voltage sensing via quenching of bioluminescence. This quenching bioluminescent voltage indicator, or Q-BOLT, pairs the dark absorbing, voltage-sensitive dipicrylamine with membrane-localized bioluminescence from the luciferase NanoLuc (NLuc). As a result, bioluminescence is quenched through resonance energy transfer (QRET) as a function of membrane potential. Fusion of HaloTag to NLuc creates a two-acceptor bioluminescence resonance energy transfer (BRET) system when a tetramethylrhodamine (TMR) HaloTag ligand is ligated to HaloTag. In this mode, Q-BOLT is capable of providing direct visualization of changes in membrane potential in live cells via three distinct readouts: change in QRET, BRET, and the ratio between bioluminescence emission and BRET. Q-BOLT can provide up to a 29% change in bioluminescence (ΔBL/BL) and >100% ΔBRET/BRET per 100 mV change in HEK 293T cells, without the need for excitation light. In cardiac monolayers derived from human-induced pluripotent stem cells (hiPSCs), Q-BOLT readily reports on membrane potential oscillations. Q-BOLT is the first example of a hybrid small molecule-protein voltage indicator that does not require excitation light and may be useful in contexts where excitation light is limiting.
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Affiliation(s)
| | | | | | | | - Thomas A. Kirkland
- Promega Biosciences LLC, San Luis Obispo, California 93401, United States
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32
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Walker AS, Raliski BK, Karbasi K, Zhang P, Sanders K, Miller EW. Optical Spike Detection and Connectivity Analysis With a Far-Red Voltage-Sensitive Fluorophore Reveals Changes to Network Connectivity in Development and Disease. Front Neurosci 2021; 15:643859. [PMID: 34054405 PMCID: PMC8155641 DOI: 10.3389/fnins.2021.643859] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/10/2021] [Indexed: 12/14/2022] Open
Abstract
The ability to optically record dynamics of neuronal membrane potential promises to revolutionize our understanding of neurobiology. In this study, we show that the far-red voltage sensitive fluorophore, Berkeley Red Sensor of Transmembrane potential-1, or BeRST 1, can be used to monitor neuronal membrane potential changes across dozens of neurons at a sampling rate of 500 Hz. Notably, voltage imaging with BeRST 1 can be implemented with affordable, commercially available illumination sources, optics, and detectors. BeRST 1 is well-tolerated in cultures of rat hippocampal neurons and provides exceptional optical recording fidelity, as judged by dual fluorescence imaging and patch-clamp electrophysiology. We developed a semi-automated spike-picking program to reduce user bias when calling action potentials and used this in conjunction with BeRST 1 to develop an optical spike and connectivity analysis (OSCA) for high-throughput dissection of neuronal activity dynamics. The high temporal resolution of BeRST 1 enables dissection of firing rate changes in response to acute, pharmacological interventions with commonly used inhibitors like gabazine and picrotoxin. Over longer periods of time, BeRST 1 also tracks chronic perturbations to neurons exposed to amyloid beta 1-42 (Aβ 1-42), revealing modest changes to spiking frequency but profound changes to overall network connectivity. Finally, we use OSCA to track changes in neuronal connectivity during maturation in culture, providing a functional readout of network assembly. We envision that use of BeRST 1 and OSCA described here will be of use to the broad neuroscience community.
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Affiliation(s)
- Alison S. Walker
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Benjamin K. Raliski
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Kaveh Karbasi
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Patrick Zhang
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Kate Sanders
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Evan W. Miller
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
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33
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Walker AS, Raliski BK, Nguyen DV, Zhang P, Sanders K, Karbasi K, Miller EW. Imaging Voltage in Complete Neuronal Networks Within Patterned Microislands Reveals Preferential Wiring of Excitatory Hippocampal Neurons. Front Neurosci 2021; 15:643868. [PMID: 34054406 PMCID: PMC8155642 DOI: 10.3389/fnins.2021.643868] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 01/28/2021] [Indexed: 12/30/2022] Open
Abstract
Voltage imaging with fluorescent dyes affords the opportunity to map neuronal activity in both time and space. One limitation to imaging is the inability to image complete neuronal networks: some fraction of cells remains outside of the observation window. Here, we combine voltage imaging, post hoc immunocytochemistry, and patterned microisland hippocampal culture to provide imaging of complete neuronal ensembles. The patterned microislands completely fill the field of view of our high-speed (500 Hz) camera, enabling reconstruction of the spiking patterns of every single neuron in the network. Cultures raised on microislands are similar to neurons grown on coverslips, with parallel developmental trajectories and composition of inhibitory and excitatory cell types (CA1, CA3, and dentate granule cells, or DGC). We calculate the likelihood that action potential firing in one neuron triggers action potential firing in a downstream neuron in a spontaneously active network to construct a functional connection map of these neuronal ensembles. Importantly, this functional map indicates preferential connectivity between DGC and CA3 neurons and between CA3 and CA1 neurons, mimicking the neuronal circuitry of the intact hippocampus. We envision that patterned microislands, in combination with voltage imaging and methods to classify cell types, will be a powerful method for exploring neuronal function in both healthy and disease states. Additionally, because the entire neuronal network is sampled simultaneously, this strategy has the power to go further, revealing all functional connections between all cell types.
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Affiliation(s)
- Alison S. Walker
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Benjamin K. Raliski
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Dat Vinh Nguyen
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Patrick Zhang
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Kate Sanders
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Kaveh Karbasi
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Evan W. Miller
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
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Lee-Montiel FT, Laemmle A, Charwat V, Dumont L, Lee CS, Huebsch N, Okochi H, Hancock MJ, Siemons B, Boggess SC, Goswami I, Miller EW, Willenbring H, Healy KE. Integrated Isogenic Human Induced Pluripotent Stem Cell-Based Liver and Heart Microphysiological Systems Predict Unsafe Drug-Drug Interaction. Front Pharmacol 2021; 12:667010. [PMID: 34025426 PMCID: PMC8138446 DOI: 10.3389/fphar.2021.667010] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/14/2021] [Indexed: 12/14/2022] Open
Abstract
Three-dimensional (3D) microphysiological systems (MPSs) mimicking human organ function in vitro are an emerging alternative to conventional monolayer cell culture and animal models for drug development. Human induced pluripotent stem cells (hiPSCs) have the potential to capture the diversity of human genetics and provide an unlimited supply of cells. Combining hiPSCs with microfluidics technology in MPSs offers new perspectives for drug development. Here, the integration of a newly developed liver MPS with a cardiac MPS—both created with the same hiPSC line—to study drug–drug interaction (DDI) is reported. As a prominent example of clinically relevant DDI, the interaction of the arrhythmogenic gastroprokinetic cisapride with the fungicide ketoconazole was investigated. As seen in patients, metabolic conversion of cisapride to non-arrhythmogenic norcisapride in the liver MPS by the cytochrome P450 enzyme CYP3A4 was inhibited by ketoconazole, leading to arrhythmia in the cardiac MPS. These results establish integration of hiPSC-based liver and cardiac MPSs to facilitate screening for DDI, and thus drug efficacy and toxicity, isogenic in the same genetic background.
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Affiliation(s)
- Felipe T Lee-Montiel
- Departments of Bioengineering, and Materials Science & Engineering, University of California Berkeley, Berkeley, CA, United States
| | - Alexander Laemmle
- Department of Surgery, Division of Transplant Surgery, Liver Center and Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA, United States.,Institute of Clinical Chemistry and Department of Pediatrics, Inselspital, University Hospital Bern, Bern, Switzerland
| | - Verena Charwat
- Departments of Bioengineering, and Materials Science & Engineering, University of California Berkeley, Berkeley, CA, United States
| | - Laure Dumont
- Department of Surgery, Division of Transplant Surgery, Liver Center and Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA, United States
| | - Caleb S Lee
- Departments of Bioengineering, and Materials Science & Engineering, University of California Berkeley, Berkeley, CA, United States
| | - Nathaniel Huebsch
- Departments of Bioengineering, and Materials Science & Engineering, University of California Berkeley, Berkeley, CA, United States
| | - Hideaki Okochi
- Department of Bioengineering and Therapeutic Sciences, Schools of Pharmacy and Medicine, University of California San Francisco, San Francisco, CA, United States
| | | | - Brian Siemons
- Departments of Bioengineering, and Materials Science & Engineering, University of California Berkeley, Berkeley, CA, United States
| | - Steven C Boggess
- Department of Chemistry, University of California Berkeley, Berkeley, CA, United States
| | - Ishan Goswami
- Departments of Bioengineering, and Materials Science & Engineering, University of California Berkeley, Berkeley, CA, United States
| | - Evan W Miller
- Departments of Chemistry and Molecular & Cell Biology, and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, United States
| | - Holger Willenbring
- Department of Surgery, Division of Transplant Surgery, Liver Center and Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA, United States
| | - Kevin E Healy
- Departments of Bioengineering, and Materials Science & Engineering, University of California Berkeley, Berkeley, CA, United States
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35
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Abstract
Membrane potential (Vmem) is a fundamental biophysical signal present in all cells. Vmem signals range in time from milliseconds to days, and they span lengths from microns to centimeters. Vmem affects many cellular processes, ranging from neurotransmitter release to cell cycle control to tissue patterning. However, existing tools are not suitable for Vmem quantification in many of these areas. In this review, we outline the diverse biology of Vmem, drafting a wish list of features for a Vmem sensing platform. We then use these guidelines to discuss electrode-based and optical platforms for interrogating Vmem. On the one hand, electrode-based strategies exhibit excellent quantification but are most effective in short-term, cellular recordings. On the other hand, optical strategies provide easier access to diverse samples but generally only detect relative changes in Vmem. By combining the respective strengths of these technologies, recent advances in optical quantification of absolute Vmem enable new inquiries into Vmem biology.
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Affiliation(s)
- Julia R Lazzari-Dean
- Department of Chemistry, University of California, Berkeley, California 94720, USA; ,
| | - Anneliese M M Gest
- Department of Chemistry, University of California, Berkeley, California 94720, USA; ,
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, California 94720, USA; ,
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA
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36
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Charrez B, Charwat V, Siemons B, Finsberg H, Miller EW, Edwards AG, Healy KE. In vitro safety "clinical trial" of the cardiac liability of drug polytherapy. Clin Transl Sci 2021; 14:1155-1165. [PMID: 33786981 PMCID: PMC8212738 DOI: 10.1111/cts.13038] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/16/2021] [Accepted: 03/17/2021] [Indexed: 02/07/2023] Open
Abstract
Only a handful of US Food and Drug Administration (FDA) Emergency Use Authorizations exist for drug and biologic therapeutics that treat severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection. Potential therapeutics include repurposed drugs, some with cardiac liabilities. We report on a chronic preclinical drug screening platform, a cardiac microphysiological system (MPS), to assess cardiotoxicity associated with repurposed hydroxychloroquine (HCQ) and azithromycin (AZM) polytherapy in a mock phase I safety clinical trial. The MPS contained human heart muscle derived from induced pluripotent stem cells. The effect of drug response was measured using outputs that correlate with clinical measurements, such as QT interval (action potential duration) and drug-biomarker pairing. Chronic exposure (10 days) of heart muscle to HCQ alone elicited early afterdepolarizations and increased QT interval past 5 days. AZM alone elicited an increase in QT interval from day 7 onward, and arrhythmias were observed at days 8 and 10. Monotherapy results mimicked clinical trial outcomes. Upon chronic exposure to HCQ and AZM polytherapy, we observed an increase in QT interval on days 4-8. Interestingly, a decrease in arrhythmias and instabilities was observed in polytherapy relative to monotherapy, in concordance with published clinical trials. Biomarkers, most of them measurable in patients' serum, were identified for negative effects of monotherapy or polytherapy on tissue contractile function, morphology, and antioxidant protection. The cardiac MPS correctly predicted clinical arrhythmias associated with QT prolongation and rhythm instabilities. This high content system can help clinicians design their trials, rapidly project cardiac outcomes, and define new monitoring biomarkers to accelerate access of patients to safe coronavirus disease 2019 (COVID-19) therapeutics.
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Affiliation(s)
- Bérénice Charrez
- Department of Bioengineering and California Institute for Quantitative Biosciences (QB3)University of California at BerkeleyBerkeleyCaliforniaUSA
| | - Verena Charwat
- Department of Bioengineering and California Institute for Quantitative Biosciences (QB3)University of California at BerkeleyBerkeleyCaliforniaUSA
| | - Brian Siemons
- Department of Bioengineering and California Institute for Quantitative Biosciences (QB3)University of California at BerkeleyBerkeleyCaliforniaUSA
| | | | - Evan W. Miller
- Department of ChemistryUniversity of CaliforniaBerkeleyCaliforniaUSA
- Helen Wills Neuroscience InstituteUniversity of California, BerkeleyBerkeleyCaliforniaUSA
- Department of Molecular and Cell BiologyUniversity of California at BerkeleyBerkeleyCaliforniaUSA
| | - Andrew G. Edwards
- Department of PharmacologySchool of MedicineUniversity of California at DavisDavisCaliforniaUSA
| | - Kevin E. Healy
- Department of Bioengineering and California Institute for Quantitative Biosciences (QB3)University of California at BerkeleyBerkeleyCaliforniaUSA
- Department of Materials Science and EngineeringUniversity of California at BerkeleyBerkeleyCaliforniaUSA
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37
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Abstract
Xanthene fluorophores, like fluorescein, have been versatile molecules across diverse fields of chemistry and life sciences. Despite the ubiquity of 3-carboxy and 3-sulfonofluorescein for the last 150 years, to date, no reports of 3-phosphonofluorescein exist. Here, we report the synthesis, spectroscopic characterization, and applications of 3-phosphonofluoresceins. The absorption and emission of 3-phosphonofluoresceins remain relatively unaltered from the parent 3-carboxyfluorescein. 3-Phosphonofluoresceins show enhanced water solubility compared to 3-carboxyfluorescein and persist in an open, visible light-absorbing state even at low pH and in low dielectric media while 3-carboxyfluoresceins tend to lactonize. In contrast, the spirocyclization tendency of 3-phosphonofluoresceins can be modulated by esterification of the phosphonic acid. The bis-acetoxymethyl ester of 3-phosphonofluorescein readily enters living cells, showing excellent accumulation (>6x) and retention (>11x), resulting in a nearly 70-fold improvement in cellular brightness compared to 3-carboxyfluorescein. In a complementary fashion, the free acid form of 3-phosphonofluorescein does not cross cellular membranes, making it ideally suited for incorporation into a voltage-sensing scaffold. We develop a new synthetic route to functionalized 3-phosphonofluoresceins to enable the synthesis of phosphono-voltage sensitive fluorophores, or phosVF2.1.Cl. Phosphono-VF2.1.Cl shows excellent membrane localization, cellular brightness, and voltage sensitivity (26% ΔF/F per 100 mV), rivaling that of sulfono-based VF dyes. In summary, we develop the first synthesis of 3-phosphonofluoresceins, characterize the spectroscopic properties of this new class of xanthene dyes, and utilize these insights to show the utility of 3-phosphonofluoresceins in intracellular imaging and membrane potential sensing.
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38
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Gest AMM, Yaeger-Weiss SK, Lazzari-Dean JR, Miller EW. VoltageFluor dyes and fluorescence lifetime imaging for optical measurement of membrane potential. Methods Enzymol 2021; 653:267-293. [PMID: 34099175 DOI: 10.1016/bs.mie.2021.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Membrane potential is a fundamental biophysical parameter common to all of cellular life. Traditional methods to measure membrane potential rely on electrodes, which are invasive and low-throughput. Optical methods to measure membrane potential are attractive because they have the potential to be less invasive and higher throughput than classic electrode based techniques. However, most optical measurements rely on changes in fluorescence intensity to detect changes in membrane potential. In this chapter, we discuss the use of fluorescence lifetime imaging microscopy (FLIM) and voltage-sensitive fluorophores (VoltageFluors, or VF dyes) to estimate the millivolt value of membrane potentials in living cells. We discuss theory, application, protocols, and shortcomings of this approach.
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Affiliation(s)
- Anneliese M M Gest
- Department of Chemistry, University of California, Berkeley, CA, United States
| | | | | | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, CA, United States; Department of Molecular & Cell Biology, University of California, Berkeley, CA, United States; Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States.
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39
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Klier PEZ, Martin JG, Miller EW. Imaging Reversible Mitochondrial Membrane Potential Dynamics with a Masked Rhodamine Voltage Reporter. J Am Chem Soc 2021; 143:4095-4099. [PMID: 33710896 DOI: 10.1021/jacs.0c13110] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mitochondria are the site of aerobic respiration, producing ATP via oxidative phosphorylation as protons flow down their electrochemical gradient through ATP synthase. This negative membrane potential across the inner mitochondrial membrane (ΔΨm) represents a fundamental biophysical parameter central to cellular life. Traditional, electrode-based methods for recording membrane potential are impossible to implement on mitochondria within intact cells. Fluorescent ΔΨm indicators based on cationic, lipophilic dyes are a common alternative, but these indicators are complicated by concentration-dependent artifacts and the requirement to maintain dye in the extracellular solution to visualize reversible ΔΨm dynamics. Here, we report the first example of a fluorescent ΔΨm reporter that does not rely on ΔΨm-dependent accumulation. We redirected the localization of a photoinduced electron transfer (PeT)-based indicator, Rhodamine Voltage Reporter (RhoVR), to mitochondria by masking the carboxylate of RhoVR 1 as an acetoxymethyl (AM) ester. Once within mitochondria, esterases remove the AM ester, trapping RhoVR inside of the mitochondrial matrix, where it can incorporate within the inner membrane and reversibly report on changes in ΔΨm. We show that this Small molecule, Permeable, Internally Redistributing for Inner membrane Targeting Rhodamine Voltage Reporter, or SPIRIT RhoVR, localizes to mitochondria across a number of different cell lines and responds reversibly to changes in ΔΨm induced by exceptionally low concentrations of the uncoupler FCCP without the need for exogenous pools of dye (unlike traditional, accumulation-based rhodamine esters). SPIRIT RhoVR is compatible with multi-color imaging, enabling simultaneous, real-time observation of cytosolic Ca2+, plasma membrane potential, and reversible ΔΨm dynamics.
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40
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Gonzalez MA, Walker AS, Cao KJ, Lazzari-Dean JR, Settineri NS, Kong EJ, Kramer RH, Miller EW. Voltage Imaging with a NIR-Absorbing Phosphine Oxide Rhodamine Voltage Reporter. J Am Chem Soc 2021; 143:2304-2314. [PMID: 33501825 PMCID: PMC7986050 DOI: 10.1021/jacs.0c11382] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The development of fluorescent dyes that emit and absorb light at wavelengths greater than 700 nm and that respond to biochemical and biophysical events in living systems remains an outstanding challenge for noninvasive optical imaging. Here, we report the design, synthesis, and application of near-infrared (NIR)-absorbing and -emitting optical voltmeter based on a sulfonated, phosphine-oxide (po) rhodamine for voltage imaging in intact retinas. We find that po-rhodamine based voltage reporters, or poRhoVRs, display NIR excitation and emission profiles at greater than 700 nm, show a range of voltage sensitivities (13 to 43% ΔF/F per 100 mV in HEK cells), and can be combined with existing optical sensors, like Ca2+-sensitive fluorescent proteins (GCaMP), and actuators, like light-activated opsins ChannelRhodopsin-2 (ChR2). Simultaneous voltage and Ca2+ imaging reveals differences in activity dynamics in rat hippocampal neurons, and pairing poRhoVR with blue-light based ChR2 affords all-optical electrophysiology. In ex vivo retinas isolated from a mouse model of retinal degeneration, poRhoVR, together with GCaMP-based Ca2+ imaging and traditional multielectrode array (MEA) recording, can provide a comprehensive physiological activity profile of neuronal activity, revealing differences in voltage and Ca2+ dynamics within hyperactive networks of the mouse retina. Taken together, these experiments establish that poRhoVR will open new horizons in optical interrogation of cellular and neuronal physiology in intact systems.
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Affiliation(s)
- Monica A. Gonzalez
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Alison S. Walker
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Helen Wills Neuroscience Institute. University of California, Berkeley, California 94720, United States
| | - Kevin J. Cao
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States
| | - Julia R. Lazzari-Dean
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Nicholas S. Settineri
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Eui Ju Kong
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Richard H. Kramer
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States
- Department of Helen Wills Neuroscience Institute. University of California, Berkeley, California 94720, United States
| | - Evan W. Miller
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States
- Department of Helen Wills Neuroscience Institute. University of California, Berkeley, California 94720, United States
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41
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Kierzek M, Deal P, Miller EW, Mukherjee S, Wachten D, Baumann A, Kaupp UB, Strünker T, Brenker C. Simultaneous Recording of Multiple Signaling Events by Frequency- and Spectrally-Tuned Multiplexing of Fluorescent Probes. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.2072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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42
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Ojala KS, Ginebaugh SP, Wu M, Miller EW, Ortiz G, Covarrubias M, Meriney SD. A high-affinity, partial antagonist effect of 3,4-diaminopyridine mediates action potential broadening and enhancement of transmitter release at NMJs. J Biol Chem 2021; 296:100302. [PMID: 33465376 PMCID: PMC7949096 DOI: 10.1016/j.jbc.2021.100302] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 01/12/2021] [Accepted: 01/14/2021] [Indexed: 12/03/2022] Open
Abstract
3,4-Diaminopyridine (3,4-DAP) increases transmitter release from neuromuscular junctions (NMJs), and low doses of 3,4-DAP (estimated to reach ∼1 μM in serum) are the Food and Drug Administration (FDA)-approved treatment for neuromuscular weakness caused by Lambert–Eaton myasthenic syndrome. Canonically, 3,4-DAP is thought to block voltage-gated potassium (Kv) channels, resulting in prolongation of the presynaptic action potential (AP). However, recent reports have shown that low millimolar concentrations of 3,4-DAP have an off-target agonist effect on the Cav1 subtype (“L-type”) of voltage-gated calcium (Cav) channels and have speculated that this agonist effect might contribute to 3,4-DAP effects on transmitter release at the NMJ. To address 3,4-DAP’s mechanism(s) of action, we first used the patch-clamp electrophysiology to characterize the concentration-dependent block of 3,4-DAP on the predominant presynaptic Kv channel subtypes found at the mammalian NMJ (Kv3.3 and Kv3.4). We identified a previously unreported high-affinity (1–10 μM) partial antagonist effect of 3,4-DAP in addition to the well-known low-affinity (0.1–1 mM) antagonist activity. We also showed that 1.5-μM DAP had no effects on Cav1.2 or Cav2.1 current. Next, we used voltage imaging to show that 1.5- or 100-μM 3,4-DAP broadened the AP waveform in a dose-dependent manner, independent of Cav1 calcium channels. Finally, we demonstrated that 1.5- or 100-μM 3,4-DAP augmented transmitter release in a dose-dependent manner and this effect was also independent of Cav1 channels. From these results, we conclude that low micromolar concentrations of 3,4-DAP act solely on Kv channels to mediate AP broadening and enhance transmitter release at the NMJ.
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Affiliation(s)
- Kristine S Ojala
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Scott P Ginebaugh
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Man Wu
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Evan W Miller
- Departments of Chemistry and Molecular & Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Gloria Ortiz
- Departments of Chemistry and Molecular & Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Manuel Covarrubias
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Stephen D Meriney
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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43
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Boggess SC, Lazzari-Dean JR, Raliski BK, Mun DM, Li AY, Turnbull JL, Miller EW. Fluorescence lifetime predicts performance of voltage sensitive fluorophores in cardiomyocytes and neurons. RSC Chem Biol 2020; 2:248-258. [PMID: 34212146 PMCID: PMC8240514 DOI: 10.1039/d0cb00152j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Voltage imaging with fluorescent indicators offers a powerful complement to traditional electrode or Ca2+-imaging approaches for monitoring electrical activity. Small molecule fluorescent indicators present the unique opportunity for exquisite control over molecular structure, enabling detailed investigations of structure/function relationships. In this paper, we tune the conjugation between aniline donors and aromatic π systems within the context of photoinduced electron transfer (PeT) based voltage indicators. We describe the design and synthesis of four new voltage-sensitive fluorophores (VoltageFluors, or VFs). Three of these dyes have higher relative voltage sensitivities (ΔF/F) than the previously-reported indicator, VF2.1.Cl. We pair these new indicators with existing VFs to construct a library of voltage indicators with varying degrees of conjugation between the aniline nitrogen lone pair and the aromatic π system. Using a combination of steady-state and time-resolved fluorescence spectroscopy, cellular electrophysiology, fluorescence lifetime imaging microscopy (FLIM), and functional imaging in mammalian neurons and human cardiomyocytes, we establish a detailed link between the photophysical properties of VF dyes and their ability to report on membrane potential dynamics with high signal-to-noise. Anilines with intermediate degrees of conjugation to the aromatic π system experience intermediate rates of PeT and possess the highest absolute voltage sensitivities. Measured using FLIM in patch-clamped HEK cells, we find that the absolute voltage sensitivity of fluorescence lifetime (Δτfl per mV), coupled with traditional fluorescence intensity-based metrics like ΔF/F and signal-to-noise ratio (SNR), provides a powerful method to both predict and understand indicator performance in cellular systems. Voltage imaging with fluorescent indicators offers a powerful complement to traditional electrode or Ca2+-imaging approaches for monitoring electrical activity.![]()
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Affiliation(s)
- Steven C Boggess
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Julia R Lazzari-Dean
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Benjamin K Raliski
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Dong Min Mun
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Amy Y Li
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Joshua L Turnbull
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
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44
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Lee S, Chung CYS, Liu P, Craciun L, Nishikawa Y, Bruemmer KJ, Hamachi I, Saijo K, Miller EW, Chang CJ. Activity-Based Sensing with a Metal-Directed Acyl Imidazole Strategy Reveals Cell Type-Dependent Pools of Labile Brain Copper. J Am Chem Soc 2020; 142:14993-15003. [PMID: 32815370 PMCID: PMC7877313 DOI: 10.1021/jacs.0c05727] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Copper is a required nutrient for life and particularly important to the brain and central nervous system. Indeed, copper redox activity is essential to maintaining normal physiological responses spanning neural signaling to metabolism, but at the same time copper misregulation is associated with inflammation and neurodegeneration. As such, chemical probes that can track dynamic changes in copper with spatial resolution, especially in loosely bound, labile forms, are valuable tools to identify and characterize its contributions to healthy and disease states. In this report, we present an activity-based sensing (ABS) strategy for copper detection in live cells that preserves spatial information by a copper-dependent bioconjugation reaction. Specifically, we designed copper-directed acyl imidazole dyes that operate through copper-mediated activation of acyl imidazole electrophiles for subsequent labeling of proximal proteins at sites of elevated labile copper to provide a permanent stain that resists washing and fixation. To showcase the utility of this new ABS platform, we sought to characterize labile copper pools in the three main cell types in the brain: neurons, astrocytes, and microglia. Exposure of each of these cell types to physiologically relevant stimuli shows distinct changes in labile copper pools. Neurons display translocation of labile copper from somatic cell bodies to peripheral processes upon activation, whereas astrocytes and microglia exhibit global decreases and increases in intracellular labile copper pools, respectively, after exposure to inflammatory stimuli. This work provides foundational information on cell type-dependent homeostasis of copper, an essential metal in the brain, as well as a starting point for the design of new activity-based probes for metals and other dynamic signaling and stress analytes in biology.
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Affiliation(s)
| | | | | | | | - Yuki Nishikawa
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
- ERATO Innovative Molecular Technology for Neuroscience Project, Japan Science and Technology Agency (JST), Kyoto 615-8530, Japan
| | | | - Itaru Hamachi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
- ERATO Innovative Molecular Technology for Neuroscience Project, Japan Science and Technology Agency (JST), Kyoto 615-8530, Japan
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45
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Kand D, Liu P, Navarro MX, Fischer LJ, Rousso-Noori L, Friedmann-Morvinski D, Winter AH, Miller EW, Weinstain R. Water-Soluble BODIPY Photocages with Tunable Cellular Localization. J Am Chem Soc 2020; 142:4970-4974. [PMID: 32115942 PMCID: PMC7302507 DOI: 10.1021/jacs.9b13219] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
Photoactivation of
bioactive molecules allows manipulation of cellular
processes with high spatiotemporal precision. The recent emergence
of visible-light excitable photoprotecting groups has the potential
to further expand the established utility of the photoactivation strategy
in biological applications by offering higher tissue penetration,
diminished phototoxicity, and compatibility with other light-dependent
techniques. Nevertheless, a critical barrier to such applications
remains the significant hydrophobicity of most visible-light excitable
photocaging groups. Here, we find that applying the conventional 2,6-sulfonation
to meso-methyl BODIPY photocages is incompatible
with their photoreaction due to an increase in the excited state barrier
for photorelease. We present a simple, remote sulfonation solution
to BODIPY photocages that imparts water solubility and provides control
over cellular permeability while retaining their favorable spectroscopic
and photoreaction properties. Peripherally disulfonated BODIPY photocages
are cell impermeable, making them useful for modulation of cell-surface
receptors, while monosulfonated BODIPY retains the ability to cross
the cellular membrane and can modulate intracellular targets. This
new approach is generalizable for controlling BODIPY localization
and was validated by sensitization of mammalian cells and neurons
by visible-light photoactivation of signaling molecules.
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Affiliation(s)
| | | | | | - Logan J Fischer
- Department of Chemistry, Iowa State University, Ames, Iowa 50010, United States
| | | | | | - Arthur H Winter
- Department of Chemistry, Iowa State University, Ames, Iowa 50010, United States
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46
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Ohata J, Krishnamoorthy L, Gonzalez MA, Xiao T, Iovan DA, Toste FD, Miller EW, Chang CJ. An Activity-Based Methionine Bioconjugation Approach To Developing Proximity-Activated Imaging Reporters. ACS Cent Sci 2020; 6:32-40. [PMID: 31989024 PMCID: PMC6978837 DOI: 10.1021/acscentsci.9b01038] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Indexed: 05/04/2023]
Abstract
Chemical probes that report on protein activity, rather than protein abundance, with spatial and temporal resolution can enable studies of their native function in biological contexts as well as provide opportunities for developing new types of biochemical reporters. Here we present a sensing platform, termed proximity-activated imaging reporter (PAIR), which combines activity-based methionine bioconjugation and antibody labeling with proximity-dependent oligonucleotide-based amplification to monitor dynamic changes of a given analyte in cells and animals through context-dependent methionine labeling of specific protein targets. We establish this PAIR method to develop sensors for imaging reactive oxygen species (ROS) and calcium ions through oxaziridine-directed labeling of reactive methionine residues on β-actin and calmodulin (CaM), respectively, where the extent of methionine bioconjugation on these protein targets can serve as an indicator of oxidative stress or calcium status. In particular, application of PAIR to activity-based CaM detection provides a method for imaging integrated calcium activity in both in vitro cell and in vivo zebrafish models. By relying on native protein biochemistry, PAIR enables redox and metal imaging without introduction of external small molecules or genetically encoded indicators that can potentially buffer the natural/existing pools. This approach can be potentially generalized to target a broader range of analytes by pairing appropriate activity-based protein probes with protein detection reagents in a proximity-driven manner, providing a starting point not only for designing new sensors but also for monitoring endogenous activity of specific protein targets in biological specimens with spatial and temporal fidelity.
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Affiliation(s)
- Jun Ohata
- Department
of Chemistry, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
| | - Lakshmi Krishnamoorthy
- Department
of Chemistry, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
| | - Monica A. Gonzalez
- Department
of Chemistry, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
| | - Tong Xiao
- Department
of Chemistry, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
| | - Diana A. Iovan
- Department
of Chemistry, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
| | - F. Dean Toste
- Department
of Chemistry, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
| | - Evan W. Miller
- Department
of Chemistry, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
| | - Christopher J. Chang
- Department
of Chemistry, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, United States
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47
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Abstract
Membrane potential is a fundamental biophysical property maintained by every cell on earth. In specialized cells like neurons, rapid changes in membrane potential drive the release of chemical neurotransmitters. Coordinated, rapid changes in neuronal membrane potential across large numbers of interconnected neurons form the basis for all of human cognition, sensory perception, and memory. Despite the importance of this highly orchestrated and distributed activity, the traditional method for recording membrane potential is through the use of highly invasive single-cell electrodes that offer only a small glimpse of the total activity within a system. Fluorescent dyes that change their optical properties in response to changes in biological voltage have the potential to provide a powerful complement to traditional electrode-based methods of inquiry. Voltage-sensitive fluorescent indicators would allow the direct observation of membrane potential changes, significantly expanding our ability to monitor membrane potential dynamics in living systems. Toward this end, we have initiated a program to design, synthesize, and apply voltage-sensitive fluorophores that report on membrane potential dynamics with high sensitivity and speed. The basis for this optical voltage sensing is membrane potential-dependent photoinduced electron transfer (PeT). Voltage-sensitive fluorophores, or VoltageFluors, possess a fluorophore, a conjugated molecular wire, and an aniline donor. At resting potentials, in which the cell has a hyperpolarized or negative potential relative to the outside of the cell, PeT from the aniline donor is enhanced and fluorescence is diminished. At depolarized potentials, the membrane potential decreases the rate of PeT, allowing an increase in fluorescence. We show that a number of different fluorophores, molecular wires, and aniline donors can be employed to generate fast and sensitive VoltageFluor dyes. Multiple lines of evidence point to a PeT-based mechanism for voltage sensing, delivering fast response kinetics (∼25 ns), good sensitivity (>60% ΔF/F), compatibility with two-photon illumination, excellent signal-to-noise, and the ability to detect neuronal and cardiac action potentials in single trials. In this Account, we provide an overview of the challenges facing the design of fluorescent voltage indicators. We trace the development of molecular wire-based fluorescent voltage indicators within our group, beginning from fluorescein-based VoltageFluor to long-wavelength indicators that use modern fluorophores like silicon rhodamine and carbofluorescein. We examine design principles for PeT-based voltage indicators, showcase the use of our recent indicators for two-photon voltage imaging in intact brains, and explore the development of hybrid indicators that can localize to genetically defined cells. Finally, we highlight outstanding challenges to and opportunities for voltage imaging.
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Affiliation(s)
- Pei Liu
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Evan W. Miller
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States
- Department of Helen Wills Neuroscience Institute. University of California, Berkeley, California 94720, United States
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48
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Deal PE, Liu P, Al-Abdullatif SH, Muller VR, Shamardani K, Adesnik H, Miller EW. Covalently Tethered Rhodamine Voltage Reporters for High Speed Functional Imaging in Brain Tissue. J Am Chem Soc 2020; 142:614-622. [PMID: 31829585 PMCID: PMC6949409 DOI: 10.1021/jacs.9b12265] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Voltage-sensitive fluorophores enable the direct visualization of membrane potential changes in living systems. To pair the speed and sensitivity of chemically synthesized fluorescent indicators with cell-type specific genetic methods, we here develop Rhodamine-based Voltage Reporters (RhoVR) that can be covalently tethered to genetically encoded, self-labeling enzymes. These chemical-genetic hybrids feature a photoinduced electron transfer triggered RhoVR voltage-sensitive indicator coupled to a chloroalkane HaloTag ligand through a long, water-soluble polyethylene glycol linker (RhoVR-Halo). When applied to cells, RhoVR-Halo dyes selectively and covalently bind to surface-expressed HaloTag enzyme on genetically modified cells. RhoVR-Halo dyes maintain high voltage sensitivities-up to 34% ΔF/F per 100 mV-and fast response times typical of untargeted RhoVRs, while gaining the selectivity of genetically encodable voltage indicators. We show that RhoVR-Halos can record action potentials in single trials from cultured rat hippocampal neurons and can be used in concert with green-fluorescent Ca2+ indicators like GCaMP to provide simultaneous voltage and Ca2+ imaging. In a brain slice, RhoVR-Halos provide exquisite labeling of defined cells and can be imaged using epifluorescence, confocal, or two-photon microscopy. Using high-speed epifluorescence microscopy, RhoVR-Halos provide a read-out of action potentials from labeled cortical neurons in a rat brain slice, without the need for trial averaging. These results demonstrate the potential of hybrid chemical-genetic voltage indicators to combine the optical performance of small-molecule chromophores with the inherent selectivity of genetically encodable systems, permitting imaging modalities inaccessible to either technique individually.
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Affiliation(s)
- Parker E. Deal
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Pei Liu
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Sarah H. Al-Abdullatif
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Vikram R. Muller
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Kiarash Shamardani
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States
- Helen Wills Neuroscience Institute. University of California, Berkeley, California 94720, United States
| | - Hillel Adesnik
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States
- Helen Wills Neuroscience Institute. University of California, Berkeley, California 94720, United States
| | - Evan W. Miller
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States
- Helen Wills Neuroscience Institute. University of California, Berkeley, California 94720, United States
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49
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Lazzari-Dean JR, Gest AM, Miller EW. Optical estimation of absolute membrane potential using fluorescence lifetime imaging. eLife 2019; 8:44522. [PMID: 31545164 PMCID: PMC6814365 DOI: 10.7554/elife.44522] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 09/16/2019] [Indexed: 12/29/2022] Open
Abstract
All cells maintain ionic gradients across their plasma membranes, producing transmembrane potentials (Vmem). Mounting evidence suggests a relationship between resting Vmem and the physiology of non-excitable cells with implications in diverse areas, including cancer, cellular differentiation, and body patterning. A lack of non-invasive methods to record absolute Vmem limits our understanding of this fundamental signal. To address this need, we developed a fluorescence lifetime-based approach (VF-FLIM) to visualize and optically quantify Vmem with single-cell resolution in mammalian cell culture. Using VF-FLIM, we report Vmem distributions over thousands of cells, a 100-fold improvement relative to electrophysiological approaches. In human carcinoma cells, we visualize the voltage response to growth factor stimulation, stably recording a 10-15 mV hyperpolarization over minutes. Using pharmacological inhibitors, we identify the source of the hyperpolarization as the Ca2+-activated K+ channel KCa3.1. The ability to optically quantify absolute Vmem with cellular resolution will allow a re-examination of its signaling roles.
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Affiliation(s)
- Julia R Lazzari-Dean
- Department of Chemistry, University of California, Berkeley, Berkeley, United States
| | - Anneliese Mm Gest
- Department of Chemistry, University of California, Berkeley, Berkeley, United States
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, Berkeley, United States.,Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, United States
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50
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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. Author Correction: Kilohertz frame-rate two-photon tomography. Nat Methods 2019; 16:932. [PMID: 31388143 DOI: 10.1038/s41592-019-0545-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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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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