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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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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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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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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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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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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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Jeong S, Yang D, Beyene AG, Del Bonis-O’Donnell JT, Gest AMM, Navarro N, Sun X, Landry MP. High-throughput evolution of near-infrared serotonin nanosensors. Sci Adv 2019; 5:eaay3771. [PMID: 31897432 PMCID: PMC6920020 DOI: 10.1126/sciadv.aay3771] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 10/30/2019] [Indexed: 05/11/2023]
Abstract
Imaging neuromodulation with synthetic probes is an emerging technology for studying neurotransmission. However, most synthetic probes are developed through conjugation of fluorescent signal transducers to preexisting recognition moieties such as antibodies or receptors. We introduce a generic platform to evolve synthetic molecular recognition on the surface of near-infrared fluorescent single-wall carbon nanotube (SWCNT) signal transducers. We demonstrate evolution of molecular recognition toward neuromodulator serotonin generated from large libraries of ~6.9 × 1010 unique ssDNA sequences conjugated to SWCNTs. This probe is reversible and produces a ~200% fluorescence enhancement upon exposure to serotonin with a K d = 6.3 μM, and shows selective responsivity over serotonin analogs, metabolites, and receptor-targeting drugs. Furthermore, this probe remains responsive and reversible upon repeat exposure to exogenous serotonin in the extracellular space of acute brain slices. Our results suggest that evolution of nanosensors could be generically implemented to develop other neuromodulator probes with synthetic molecular recognition.
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Affiliation(s)
- Sanghwa Jeong
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Darwin Yang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Abraham G. Beyene
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | | | - Anneliese M. M. Gest
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nicole Navarro
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Xiaoqi Sun
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Markita P. Landry
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Institute (IGI), Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, QB3, University of California, Berkeley, Berkeley, CA 94720, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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Gest AMM, Aguiluz EM, Mays MT, Liu X, Neidhart EK, Witus LS. A colorimetric competitive displacement assay for the evaluation of catalytic peptides. Org Biomol Chem 2017; 15:10160-10163. [PMID: 29182189 DOI: 10.1039/c7ob02032e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
An indicator displacement assay has been adapted to detect the diol products of the aldol reaction between 4-nitrobenzaldehyde and hydroxyacetone in crude reaction mixtures. This provides a rapid colorimetric method of detecting product formation and thus evaluating potential catalysts, which is demonstrated using multiple catalytic peptides.
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Affiliation(s)
- Anneliese M M Gest
- Department of Chemistry, Macalester College, 1600 Grand Ave., Saint Paul, MN 55105, USA.
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