1
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Martinez KN, Gerstner NC, Yang SJ, Miller EW. Extended voltage imaging in cardiomyocytes with a triplet state quencher-stabilized silicon rhodamine. Bioorg Med Chem Lett 2024; 109:129842. [PMID: 38844174 DOI: 10.1016/j.bmcl.2024.129842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 05/17/2024] [Accepted: 06/02/2024] [Indexed: 06/18/2024]
Abstract
Voltage imaging of cardiac electrophysiology with voltage-sensitive dyes has long been a powerful complement to traditional methods like patch-clamp electrophysiology. Chemically synthesized voltage sensitive fluorophores offer flexibility for imaging in sensitive samples like human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs), since they do not require genetic transformation of the sample. One serious concern for any fluorescent voltage indicator, whether chemically synthesized or genetically encoded, is phototoxicity. We have been exploring self-healing fluorophores that use triplet state quenchers (TSQs) as a means to reduce the already low phototoxicity of VoltageFluor dyes developed in our lab. We previously showed that conjugation of the TSQ cyclooctatetraene (COT) to a fluorescein based VoltageFluor dye substantially reduced phototoxicity. Here, we show that this approach can be applied to far-red Silicon rhodamine dyes. COT-conjugated Si-rhodamines show improved photostability and reduced phototoxicity in hiPSC-CMs compared to the unmodified dye. This enables imaging of hiPSC-CMs for up to 30 min with continuous illumination. We show that this effect is mediated by a combination of reduced singlet oxygen production and lower loading in the cellular membrane. We discuss future applications and avenues of improvement for TSQ-stabilized VoltageFluor dyes.
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Affiliation(s)
- Kayli N Martinez
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-1460, USA
| | - Nels C Gerstner
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-1460, USA
| | - Samantha J Yang
- 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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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] [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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Ma J, Sun R, Xia K, Xia Q, Liu Y, Zhang X. Design and Application of Fluorescent Probes to Detect Cellular Physical Microenvironments. Chem Rev 2024; 124:1738-1861. [PMID: 38354333 DOI: 10.1021/acs.chemrev.3c00573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2024]
Abstract
The microenvironment is indispensable for functionality of various biomacromolecules, subcellular compartments, living cells, and organisms. In particular, physical properties within the biological microenvironment could exert profound effects on both the cellular physiology and pathology, with parameters including the polarity, viscosity, pH, and other relevant factors. There is a significant demand to directly visualize and quantitatively measure the fluctuation in the cellular microenvironment with spatiotemporal resolution. To satisfy this need, analytical methods based on fluorescence probes offer great opportunities due to the facile, sensitive, and dynamic detection that these molecules could enable in varying biological settings from in vitro samples to live animal models. Herein, we focus on various types of small molecule fluorescent probes for the detection and measurement of physical parameters of the microenvironment, including pH, polarity, viscosity, mechanical force, temperature, and electron potential. For each parameter, we primarily describe the chemical mechanisms underlying how physical properties are correlated with changes of various fluorescent signals. This review provides both an overview and a perspective for the development of small molecule fluorescent probes to visualize the dynamic changes in the cellular environment, to expand the knowledge for biological process, and to enrich diagnostic tools for human diseases.
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Affiliation(s)
- Junbao Ma
- Department of Chemistry and Research Center for Industries of the Future, Westlake University, 600 Dunyu Road, Hangzhou 310030, Zhejiang Province, China
- Westlake Laboratory of Life Sciences and Biomedicine, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310030, Zhejiang Province, China
| | - Rui Sun
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
- University of the Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Kaifu Xia
- Department of Chemistry and Research Center for Industries of the Future, Westlake University, 600 Dunyu Road, Hangzhou 310030, Zhejiang Province, China
- Westlake Laboratory of Life Sciences and Biomedicine, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310030, Zhejiang Province, China
| | - Qiuxuan Xia
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
- University of the Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Yu Liu
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
- State Key Laboratory of Medical Proteomics, National Chromatographic R. & A. Center, Chinese Academy of Sciences Dalian Liaoning 116023, China
| | - Xin Zhang
- Department of Chemistry and Research Center for Industries of the Future, Westlake University, 600 Dunyu Road, Hangzhou 310030, Zhejiang Province, China
- Westlake Laboratory of Life Sciences and Biomedicine, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
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4
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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 : THE PREPRINT SERVER FOR BIOLOGY 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] [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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5
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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] [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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6
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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: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [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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7
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Fiala T, Mosharov EV, Wang J, Mendieta AM, Choi SJ, Fialova E, Hwu C, Sulzer D, Sames D. Chemical Targeting of Rhodol Voltage-Sensitive Dyes to Dopaminergic Neurons. ACS Chem Neurosci 2022; 13:1251-1262. [PMID: 35400149 DOI: 10.1021/acschemneuro.1c00862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Optical imaging of changes in the membrane potential of living cells can be achieved by means of fluorescent voltage-sensitive dyes (VSDs). A particularly challenging task is to efficiently deliver these highly lipophilic probes to specific neuronal subpopulations in brain tissue. We have tackled this task by designing a solubilizing, hydrophilic polymer platform that carries a high-affinity ligand for a membrane protein marker of interest and a fluorescent VSD. Here, we disclose an improved design of polymer-supported probes for chemical, nongenetic targeting of voltage sensors to axons natively expressing the dopamine transporter in ex vivo mouse brain tissue. We first show that for negatively charged rhodol VSDs functioning on the photoinduced electron transfer principle, poly(ethylene glycol) as a carrier enables targeting with higher selectivity than the polysaccharide dextran in HEK cell culture. In the same experimental setting, we also demonstrate that incorporation of an azetidine ring into the rhodol chromophore substantially increases the brightness and voltage sensitivity of the respective VSD. We show that the superior properties of the optimized sensor are transferable to recording of electrically evoked activity from dopaminergic axons in mouse striatal slices after averaging of multiple trials. Finally, we suggest the next milestones for the field to achieve single-scan recordings with nongenetically targeted VSDs in native brain tissue.
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Affiliation(s)
- Tomas Fiala
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Eugene V. Mosharov
- Department of Neurology, Columbia University Irving Medical Center, New York, New York 10032, United States
| | - Jihang Wang
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Adriana M. Mendieta
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Se Joon Choi
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York 10032, United States
| | - Eva Fialova
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Christopher Hwu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - David Sulzer
- Department of Neurology, Columbia University Irving Medical Center, New York, New York 10032, United States
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York 10032, United States
- Department of Pharmacology, Columbia University Irving Medical Center, New York, New York 10032, United States
- Department of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, United States
| | - Dalibor Sames
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- NeuroTechnology Center at Columbia University, New York, New York 10027, United States
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8
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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 CENTRAL SCIENCE 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] [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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9
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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: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [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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10
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Post MR, Sulzer D. The chemical tools for imaging dopamine release. Cell Chem Biol 2021; 28:748-764. [PMID: 33894160 PMCID: PMC8532025 DOI: 10.1016/j.chembiol.2021.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/23/2021] [Accepted: 04/06/2021] [Indexed: 02/07/2023]
Abstract
Dopamine is a modulatory neurotransmitter involved in learning, motor functions, and reward. Many neuropsychiatric disorders, including Parkinson's disease, autism, and schizophrenia, are associated with imbalances or dysfunction in the dopaminergic system. Yet, our understanding of these pervasive public health issues is limited by our ability to effectively image dopamine in humans, which has long been a goal for chemists and neuroscientists. The last two decades have witnessed the development of many molecules used to trace dopamine. We review the small molecules, nanoparticles, and protein sensors used with fluorescent microscopy/photometry, MRI, and PET that shape dopamine research today. None of these tools observe dopamine itself, but instead harness the biology of the dopamine system-its synthetic and metabolic pathways, synaptic vesicle cycle, and receptors-in elegant ways. Their advantages and weaknesses are covered here, along with recent examples and the chemistry and biology that allow them to function.
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Affiliation(s)
- Michael R Post
- Department of Psychiatry, Columbia University Medical Center, New York, NY, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA.
| | - David Sulzer
- Departments of Psychiatry, Neurology, and Pharmacology, Columbia University Medical Center, New York, NY, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA.
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11
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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] [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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12
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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: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [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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13
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Schreiber CL, Zhai C, Smith BD. Chiral figure-eight molecular scaffold for fluorescent probe development. Org Biomol Chem 2021; 19:3213-3219. [PMID: 33885576 PMCID: PMC8075008 DOI: 10.1039/d1ob00306b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Targeted fluorescent molecular probes are useful for cell microscopy, diagnostics, and biological imaging. An emerging discovery paradigm is to screen libraries of fluorescent molecules and identify hit compounds with interesting targeting properties. However, a current limitation with this approach is the lack of fluorescent molecular scaffolds that can produce libraries of probe candidates with three dimensional globular shape, chiral centers, and constrained conformation. This study evaluated a new probe scaffold called squaraine figure-eight (SF8), a self-threaded molecular architecture that is comprised of an encapsulated deep-red fluorescent squaraine dye, surrounding tetralactam macrocycle, and peripheral loops. Easy synthetic variation of the loops produced four chiral isomeric SF8 probes, with the same log P values. Cell microscopy showed that subtle changes in the loop structure led to significant differences in intracellular targeting. Most notably, a comparison of enantiomeric probes revealed a large difference in mitochondrial accumulation, very likely due to differences in affinity for a chiral biomarker within the organelle. A tangible outcome of the research is a probe candidate that can be: (a) developed further as a bright and photostable, deep-red fluorescent probe for mitochondrial imaging, and (b) used as a molecular tool to identify the mitochondrial biomarker for selective targeting. It will be straightforward to expand the SF8 probe chemical space and produce structurally diverse probe libraries with high potential for selective targeting of a wide range of biomarkers.
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Affiliation(s)
- Cynthia L Schreiber
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA.
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14
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Choquet D, Sainlos M, Sibarita JB. Advanced imaging and labelling methods to decipher brain cell organization and function. Nat Rev Neurosci 2021; 22:237-255. [PMID: 33712727 DOI: 10.1038/s41583-021-00441-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2021] [Indexed: 01/31/2023]
Abstract
The brain is arguably the most complex organ. The branched and extended morphology of nerve cells, their subcellular complexity, the multiplicity of brain cell types as well as their intricate connectivity and the scattering properties of brain tissue present formidable challenges to the understanding of brain function. Neuroscientists have often been at the forefront of technological and methodological developments to overcome these hurdles to visualize, quantify and modify cell and network properties. Over the last few decades, the development of advanced imaging methods has revolutionized our approach to explore the brain. Super-resolution microscopy and tissue imaging approaches have recently exploded. These instrumentation-based innovations have occurred in parallel with the development of new molecular approaches to label protein targets, to evolve new biosensors and to target them to appropriate cell types or subcellular compartments. We review the latest developments for labelling and functionalizing proteins with small localization and functionalized reporters. We present how these molecular tools are combined with the development of a wide variety of imaging methods that break either the diffraction barrier or the tissue penetration depth limits. We put these developments in perspective to emphasize how they will enable step changes in our understanding of the brain.
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Affiliation(s)
- Daniel Choquet
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France. .,University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4, Bordeaux, France.
| | - Matthieu Sainlos
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France.
| | - Jean-Baptiste Sibarita
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France.
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15
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Zhang H, He X, Li X, Guo L, Meng F, Yang R, Li C, Liu Z, Yu X. Permeability-Controllable Potentiometric Fluorescent Probes Enable Visually Discriminating Near-Zero and Normal Situations of Cell Membrane Potential. Anal Chem 2021; 93:2728-2732. [PMID: 33476124 DOI: 10.1021/acs.analchem.0c04928] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The permeability-controllable potentiometric fluorescent probes that can visually discriminate near-zero and normal situations of cell membrane potential were reported for the first time. Different from traditional potentiometric probes that utilize fluorescence intensity to reflect membrane potential, CQ12 and CP12 have different localizations under the two situations of cell membrane potential. Thus, the two situations can be point-to-point indicated by two fluorescent images with an obvious difference, avoiding complex operations and calibration of conventional methods.
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Affiliation(s)
- Huamiao Zhang
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Xiuquan He
- Department of Anatomy, School of Basic Medical Sciences, Shandong University, Jinan 250012, P. R. China.,Advanced Medical Research Institute, Shandong University, Jinan 250012, P. R. China
| | - Xuechen Li
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Lifang Guo
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Fangfang Meng
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Rui Yang
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Chuanya Li
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Zhiqiang Liu
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Xiaoqiang Yu
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China.,Advanced Medical Research Institute, Shandong University, Jinan 250012, P. R. China
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16
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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] [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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17
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Bruemmer KJ, Crossley SWM, Chang CJ. Activity-Based Sensing: A Synthetic Methods Approach for Selective Molecular Imaging and Beyond. Angew Chem Int Ed Engl 2020; 59:13734-13762. [PMID: 31605413 PMCID: PMC7665898 DOI: 10.1002/anie.201909690] [Citation(s) in RCA: 144] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Indexed: 01/10/2023]
Abstract
Emerging from the origins of supramolecular chemistry and the development of selective chemical receptors that rely on lock-and-key binding, activity-based sensing (ABS)-which utilizes molecular reactivity rather than molecular recognition for analyte detection-has rapidly grown into a distinct field to investigate the production and regulation of chemical species that mediate biological signaling and stress pathways, particularly metal ions and small molecules. Chemical reactions exploit the diverse chemical reactivity of biological species to enable the development of selective and sensitive synthetic methods to decipher their contributions within complex living environments. The broad utility of this reaction-driven approach facilitates application to imaging platforms ranging from fluorescence, luminescence, photoacoustic, magnetic resonance, and positron emission tomography modalities. ABS methods are also being expanded to other fields, such as drug and materials discovery.
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Affiliation(s)
- Kevin J Bruemmer
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Steven W M Crossley
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Christopher J Chang
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, 94720, USA
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18
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Jun JV, Chenoweth DM, Petersson EJ. Rational design of small molecule fluorescent probes for biological applications. Org Biomol Chem 2020; 18:5747-5763. [PMID: 32691820 PMCID: PMC7453994 DOI: 10.1039/d0ob01131b] [Citation(s) in RCA: 107] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Fluorescent small molecules are powerful tools for visualizing biological events, embodying an essential facet of chemical biology. Since the discovery of the first organic fluorophore, quinine, in 1845, both synthetic and theoretical efforts have endeavored to "modulate" fluorescent compounds. An advantage of synthetic dyes is the ability to employ modern organic chemistry strategies to tailor chemical structures and thereby rationally tune photophysical properties and functionality of the fluorophore. This review explores general factors affecting fluorophore excitation and emission spectra, molar absorption, Stokes shift, and quantum efficiency; and provides guidelines for chemist to create novel probes. Structure-property relationships concerning the substituents are discussed in detail with examples for several dye families. We also present a survey of functional probes based on PeT, FRET, and environmental or photo-sensitivity, focusing on representative recent work in each category. We believe that a full understanding of dyes with diverse chemical moieties enables the rational design of probes for the precise interrogation of biochemical and biological phenomena.
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Affiliation(s)
- Joomyung V Jun
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104, USA. and Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - David M Chenoweth
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104, USA.
| | - E James Petersson
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104, USA. and Department of Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, 3700 Hamilton Walk, Philadelphia, PA 19104, USA
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19
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Bruemmer KJ, Crossley SWM, Chang CJ. Aktivitätsbasierte Sensorik: ein synthetisch‐methodischer Ansatz für die selektive molekulare Bildgebung und darüber hinaus. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201909690] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kevin J. Bruemmer
- Department of Chemistry University of California, Berkeley Berkeley CA 94720 USA
| | | | - Christopher J. Chang
- Department of Chemistry University of California, Berkeley Berkeley CA 94720 USA
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute University of California, Berkeley Berkeley CA 94720 USA
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20
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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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21
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Franke JM, Raliski BK, Boggess SC, Natesan DV, Koretsky ET, Zhang P, Kulkarni RU, Deal PE, Miller EW. BODIPY Fluorophores for Membrane Potential Imaging. J Am Chem Soc 2019; 141:12824-12831. [PMID: 31339313 PMCID: PMC7285656 DOI: 10.1021/jacs.9b05912] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluorophores based on the BODIPY scaffold are prized for their tunable excitation and emission profiles, mild syntheses, and biological compatibility. Improving the water-solubility of BODIPY dyes remains an outstanding challenge. The development of water-soluble BODIPY dyes usually involves direct modification of the BODIPY fluorophore core with ionizable groups or substitution at the boron center. While these strategies are effective for the generation of water-soluble fluorophores, they are challenging to implement when developing BODIPY-based indicators: direct modification of BODIPY core can disrupt the electronics of the dye, complicating the design of functional indicators; and substitution at the boron center often renders the resultant BODIPY incompatible with the chemical transformations required to generate fluorescent sensors. In this study, we show that BODIPYs bearing a sulfonated aromatic group at the meso position provide a general solution for water-soluble BODIPYs. We outline the route to a suite of 5 new sulfonated BODIPYs with 2,6-disubstitution patterns spanning a range of electron-donating and -withdrawing propensities. To highlight the utility of these new, sulfonated BODIPYs, we further functionalize them to access 13 new, BODIPY-based, voltage-sensitive fluorophores (VF). The most sensitive of these BODIPY VF dyes displays a 48% ΔF/F per 100 mV in mammalian cells. Two additional BODIPY VFs show good voltage sensitivity (≥24% ΔF/F) and excellent brightness in cells. These compounds can report on action potential dynamics in both mammalian neurons and human stem cell-derived cardiomyocytes. Accessing a range of substituents in the context of a water-soluble BODIPY fluorophore provides opportunities to tune the electronic properties of water-soluble BODIPY dyes for functional indicators.
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Affiliation(s)
- Jenna M. Franke
- 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
| | - Steven C. Boggess
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Divya V. Natesan
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Evan T. Koretsky
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Patrick Zhang
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Rishikesh U. Kulkarni
- 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
| | - 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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