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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Liu X, Chen Y, Hang C, Cheng J, Peng D, Li Y, Jiang X. Coupling Nanoscale Precision with Multiscale Imaging: A Multifunctional Near-Infrared Dye for the Brain. ACS NANO 2024; 18:22233-22244. [PMID: 39102625 DOI: 10.1021/acsnano.4c06103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/07/2024]
Abstract
Live imaging of primary neural cells is crucial for monitoring neuronal activity, especially multiscale and multifunctional imaging that offers excellent biocompatibility. Multiscale imaging can provide insights into cellular structure and function from the nanoscale to the millimeter scale. Multifunctional imaging can monitor different activities in the brain. However, this remains a challenge because of the lack of dyes with a high signal-to-background ratio, water solubility, and multiscale and multifunctional imaging capabilities. In this study, we present a neural dye with near-infrared (NIR) emissions (>700 nm) that enables ultrafast staining (in less than 1 min) for the imaging of primary neurons. This dye not only enables multiscale neural live-cell imaging from vesicles in neurites, neural membranes, and single neurons to the whole brain but also facilitates multifunctional imaging, such as the monitoring and quantifying of synaptic vesicles and the changes in membrane potential. We also explore the potential of this NIR neural dye for staining brain slices and live brains. The NIR neural dye exhibits superior binding with neural membranes compared to commercial dyes, thereby achieving multiscale and multifunctional brain neuroimaging. In conclusion, our findings introduce a significant breakthrough in neuroimaging dyes by developing a category of small molecular dyes.
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Affiliation(s)
- Xiaoyan Liu
- Shenzhen Key Laboratory of Smart Healthcare Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Department of Biomedical Engineering, Southern University of Science and Technology, No. 1088 Xueyuan Road, Nanshan District, Shenzhen 518055, China
| | - Yao Chen
- Shenzhen Key Laboratory of Smart Healthcare Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Department of Biomedical Engineering, Southern University of Science and Technology, No. 1088 Xueyuan Road, Nanshan District, Shenzhen 518055, China
| | - Chen Hang
- Shenzhen Key Laboratory of Smart Healthcare Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Department of Biomedical Engineering, Southern University of Science and Technology, No. 1088 Xueyuan Road, Nanshan District, Shenzhen 518055, China
| | - Jinxiong Cheng
- Shenzhen Key Laboratory of Smart Healthcare Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Department of Biomedical Engineering, Southern University of Science and Technology, No. 1088 Xueyuan Road, Nanshan District, Shenzhen 518055, China
| | - Dinglu Peng
- Shenzhen Key Laboratory of Smart Healthcare Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Department of Biomedical Engineering, Southern University of Science and Technology, No. 1088 Xueyuan Road, Nanshan District, Shenzhen 518055, China
| | - Ying Li
- Innovation Research Center for AIE Pharmaceutical Biology, Guangzhou Municipal and Guangdong Provincial Key Laboratory of Molecular Target & Clinical Pharmacology, the NMPA and State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou 511436, China
| | - Xingyu Jiang
- Shenzhen Key Laboratory of Smart Healthcare Engineering, Guangdong Provincial Key Laboratory of Advanced Biomaterials, Department of Biomedical Engineering, Southern University of Science and Technology, No. 1088 Xueyuan Road, Nanshan District, Shenzhen 518055, China
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3
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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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4
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Zhang Y, Ling J, Liu T, Chen Z. Lumos maxima - How robust fluorophores resist photobleaching? Curr Opin Chem Biol 2024; 79:102439. [PMID: 38432145 DOI: 10.1016/j.cbpa.2024.102439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/13/2024] [Accepted: 02/13/2024] [Indexed: 03/05/2024]
Abstract
Fluorescent dyes synergize with advanced microscopy for researchers to investigate the location and dynamic processes of biomacromolecules with high spatial and temporal resolution. However, the instability of fluorescent dyes, including photobleaching and photoconversion, represent fundamental limits for super-resolution and time-lapse imaging. In this review, we discuss the latest advances in improving the photostability of fluorescent dyes. We summarize the primary photobleaching processes of cyanine and rhodamine dyes and highlight a range of strategies developed in recent years to strengthen these fluorophores. Additionally, we discuss the influence of protein microenvironments and labeling methods on the photostability of fluorophores. We aim to inspire next-generation robust and bright fluorophores that ultimately enable the routine practice of time-lapse super-resolution imaging of live cells.
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Affiliation(s)
- Yuan Zhang
- College of Future Technology, Institute of Molecular Medicine, National Biomedical Imaging Center, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Jing Ling
- Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Tianyan Liu
- Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Zhixing Chen
- College of Future Technology, Institute of Molecular Medicine, National Biomedical Imaging Center, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China; PKU-Nanjing Institute of Translational Medicine, Nanjing 211800, China.
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5
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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] [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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Xiang Y, Shi K, Li Y, Xue J, Tong Z, Li H, Li Z, Teng C, Fang J, Hu N. Active Micro-Nano-Collaborative Bioelectronic Device for Advanced Electrophysiological Recording. NANO-MICRO LETTERS 2024; 16:132. [PMID: 38411852 PMCID: PMC10899154 DOI: 10.1007/s40820-024-01336-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 12/28/2023] [Indexed: 02/28/2024]
Abstract
The development of precise and sensitive electrophysiological recording platforms holds the utmost importance for research in the fields of cardiology and neuroscience. In recent years, active micro/nano-bioelectronic devices have undergone significant advancements, thereby facilitating the study of electrophysiology. The distinctive configuration and exceptional functionality of these active micro-nano-collaborative bioelectronic devices offer the potential for the recording of high-fidelity action potential signals on a large scale. In this paper, we review three-dimensional active nano-transistors and planar active micro-transistors in terms of their applications in electro-excitable cells, focusing on the evaluation of the effects of active micro/nano-bioelectronic devices on electrophysiological signals. Looking forward to the possibilities, challenges, and wide prospects of active micro-nano-devices, we expect to advance their progress to satisfy the demands of theoretical investigations and medical implementations within the domains of cardiology and neuroscience research.
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Affiliation(s)
- Yuting Xiang
- Department of Chemistry, Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 310058, People's Republic of China
- Department of Obstetrics and Gynecology, The Tenth Affiliated Hospital, Southern Medical University, Dongguan, 523059, People's Republic of China
- Dongguan Key Laboratory of Major Diseases in Obstetrics and Gynecology, Dongguan, 523059, People's Republic of China
| | - Keda Shi
- Department of Lung Transplantation and General Thoracic Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, People's Republic of China
| | - Ying Li
- School of Basic Medical Sciences, Zhejiang Chinese Medical University, Hangzhou, 310053, People's Republic of China
| | - Jiajin Xue
- General Surgery Department, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Children's Health, Hangzhou, 310052, People's Republic of China
| | - Zhicheng Tong
- Department of Orthopedics, The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, 322005, People's Republic of China
| | - Huiming Li
- Department of Orthopedics, The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, 322005, People's Republic of China
| | - Zhongjun Li
- Department of Obstetrics and Gynecology, The Tenth Affiliated Hospital, Southern Medical University, Dongguan, 523059, People's Republic of China.
- Dongguan Key Laboratory of Major Diseases in Obstetrics and Gynecology, Dongguan, 523059, People's Republic of China.
| | - Chong Teng
- Department of Orthopedics, The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, 322005, People's Republic of China.
| | - Jiaru Fang
- School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou, 510006, People's Republic of China.
| | - Ning Hu
- Department of Chemistry, Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 310058, People's Republic of China.
- General Surgery Department, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Children's Health, Hangzhou, 310052, People's Republic of China.
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7
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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: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [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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8
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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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9
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Messina MS, Chang CJ. Chemical Sensors and Imaging: Molecular, Materials, and Biological Platforms. ACS CENTRAL SCIENCE 2023; 9:1706-1711. [PMID: 37780366 PMCID: PMC10540294 DOI: 10.1021/acscentsci.3c01070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
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10
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Liu S, Ling J, Chen P, Cao C, Peng L, Zhang Y, Ji G, Guo Y, Chen PR, Zou P, Chen Z. Orange/far-red hybrid voltage indicators with reduced phototoxicity enable reliable long-term imaging in neurons and cardiomyocytes. Proc Natl Acad Sci U S A 2023; 120:e2306950120. [PMID: 37590412 PMCID: PMC10450445 DOI: 10.1073/pnas.2306950120] [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: 04/28/2023] [Accepted: 07/12/2023] [Indexed: 08/19/2023] Open
Abstract
Hybrid voltage indicators (HVIs) are chemogenetic sensors that combines the superior photophysical properties of organic dyes and the genetic targetability of protein sensors to report transient membrane voltage changes. They exhibit boosted sensitivity in excitable cells such as neurons and cardiomyocytes. However, the voltage signals recorded during long-term imaging are severely diminished or distorted due to phototoxicity and photobleaching issues. To capture stable electrophysiological activities over a long time, we employ cyanine dyes conjugated with a cyclooctatetraene (COT) molecule as the fluorescence reporter of HVI. The resulting orange-emitting HVI-COT-Cy3 enables high-fidelity voltage imaging for up to 30 min in cultured primary neurons with a sensitivity of ~ -30% ΔF/F0 per action potential (AP). It also maximally preserves the signal of individual APs in cardiomyocytes. The far-red-emitting HVI-COT-Cy5 allows two-color voltage/calcium imaging with GCaMP6s in neurons and cardiomyocytes for 15 min. We leverage the HVI-COT series with reduced phototoxicity and photobleaching to evaluate the impact of drug candidates on the electrophysiology of excitable cells.
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Affiliation(s)
- Shuzhang Liu
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of the Ministry of Education, Peking University, Beijing100871, China
- IDG/McGovern Institute for Brain Research at Peking University, Beijing100871, China
| | - Jing Ling
- Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
- College of Future Technology, Institute of Molecular Medicine, National Biomedical Imaging Center, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing100871, China
| | - Peng Chen
- Peking University-Nanjing Institute of Translational Medicine, Nanjing211800, China
- Genvivo Biotech, Nanjing211800, China
| | - Chang Cao
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of the Ministry of Education, Peking University, Beijing100871, China
| | - Luxin Peng
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of the Ministry of Education, Peking University, Beijing100871, China
| | - Yuan Zhang
- College of Future Technology, Institute of Molecular Medicine, National Biomedical Imaging Center, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing100871, China
| | - Guangshen Ji
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing100871, China
| | - Yingna Guo
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing100871, China
| | - Peng R. Chen
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of the Ministry of Education, Peking University, Beijing100871, China
- Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
| | - Peng Zou
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of the Ministry of Education, Peking University, Beijing100871, China
- IDG/McGovern Institute for Brain Research at Peking University, Beijing100871, China
- Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
- Chinese Institute for Brain Research, Beijing102206, China
| | - Zhixing Chen
- Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
- College of Future Technology, Institute of Molecular Medicine, National Biomedical Imaging Center, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing100871, China
- Peking University-Nanjing Institute of Translational Medicine, Nanjing211800, China
- Genvivo Biotech, Nanjing211800, China
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11
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Peyear TA, Andersen OS. Screening for bilayer-active and likely cytotoxic molecules reveals bilayer-mediated regulation of cell function. J Gen Physiol 2023; 155:e202213247. [PMID: 36763053 PMCID: PMC9948646 DOI: 10.1085/jgp.202213247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 12/06/2022] [Accepted: 01/13/2023] [Indexed: 02/11/2023] Open
Abstract
A perennial problem encountered when using small molecules (drugs) to manipulate cell or protein function is to assess whether observed changes in function result from specific interactions with a desired target or from less specific off-target mechanisms. This is important in laboratory research as well as in drug development, where the goal is to identify molecules that are unlikely to be successful therapeutics early in the process, thereby avoiding costly mistakes. We pursued this challenge from the perspective that many bioactive molecules (drugs) are amphiphiles that alter lipid bilayer elastic properties, which may cause indiscriminate changes in membrane protein (and cell) function and, in turn, cytotoxicity. Such drug-induced changes in bilayer properties can be quantified as changes in the monomer↔dimer equilibrium for bilayer-spanning gramicidin channels. Using this approach, we tested whether molecules in the Pathogen Box (a library of 400 drugs and drug-like molecules with confirmed activity against tropical diseases released by Medicines for Malaria Venture to encourage the development of therapies for neglected tropical diseases) are bilayer modifiers. 32% of the molecules in the Pathogen Box were bilayer modifiers, defined as molecules that at 10 µM shifted the monomer↔dimer equilibrium toward the conducting dimers by at least 50%. Correlation analysis of the molecules' reported HepG2 cell cytotoxicity to bilayer-modifying potency, quantified as the shift in the gramicidin monomer↔dimer equilibrium, revealed that molecules producing <25% change in the equilibrium had significantly lower probability of being cytotoxic than molecules producing >50% change. Neither cytotoxicity nor bilayer-modifying potency (quantified as the shift in the gramicidin monomer↔dimer equilibrium) was well predicted by conventional physico-chemical descriptors (hydrophobicity, polar surface area, etc.). We conclude that drug-induced changes in lipid bilayer properties are robust predictors of the likelihood of membrane-mediated off-target effects, including cytotoxicity.
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Affiliation(s)
- Thasin A. Peyear
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
- Graduate Program in Physiology, Biophysics and Systems Biology, Weill Cornell Graduate School of Medical Sciences. New York, NY, USA
| | - Olaf S. Andersen
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
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12
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Multi-color live-cell STED nanoscopy of mitochondria with a gentle inner membrane stain. Proc Natl Acad Sci U S A 2022; 119:e2215799119. [PMID: 36534799 PMCID: PMC9907107 DOI: 10.1073/pnas.2215799119] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Capturing mitochondria's intricate and dynamic structure poses a daunting challenge for optical nanoscopy. Different labeling strategies have been demonstrated for live-cell stimulated emission depletion (STED) microscopy of mitochondria, but orthogonal strategies are yet to be established, and image acquisition has suffered either from photodamage to the organelles or from rapid photobleaching. Therefore, live-cell nanoscopy of mitochondria has been largely restricted to two-dimensional (2D) single-color recordings of cancer cells. Here, by conjugation of cyclooctatetraene (COT) to a benzo-fused cyanine dye, we report a mitochondrial inner membrane (IM) fluorescent marker, PK Mito Orange (PKMO), featuring efficient STED at 775 nm, strong photostability, and markedly reduced phototoxicity. PKMO enables super-resolution (SR) recordings of IM dynamics for extended periods in immortalized mammalian cell lines, primary cells, and organoids. Photostability and reduced phototoxicity of PKMO open the door to live-cell three-dimensional (3D) STED nanoscopy of mitochondria for 3D analysis of the convoluted IM. PKMO is optically orthogonal with green and far-red markers, allowing multiplexed recordings of mitochondria using commercial STED microscopes. Using multi-color STED microscopy, we demonstrate that imaging with PKMO can capture interactions of mitochondria with different cellular components such as the endoplasmic reticulum (ER) or the cytoskeleton, Bcl-2-associated X protein (BAX)-induced apoptotic process, or crista phenotypes in genetically modified cells, all at sub-100 nm resolution. Thereby, this work offers a versatile tool for studying mitochondrial IM architecture and dynamics in a multiplexed manner.
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Liu M, Zhang J, Chen Z. Emerging Trends in Fluorescence Bioimaging of Divalent Metal Cations Using Small‐Molecule Indicators. Chemistry 2022; 28:e202200587. [DOI: 10.1002/chem.202200587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Mingqiao Liu
- College of Future Technology Institute of Molecular Medicine National Biomedical Imaging Center Beijing Key Laboratory of Cardiometabolic Molecular Medicine Peking University 100871 Beijing China
- Academy for Advanced Interdisciplinary Studies Peking University 100871 Beijing China
| | - Junwei Zhang
- College of Future Technology Institute of Molecular Medicine National Biomedical Imaging Center Beijing Key Laboratory of Cardiometabolic Molecular Medicine Peking University 100871 Beijing China
| | - Zhixing Chen
- College of Future Technology Institute of Molecular Medicine National Biomedical Imaging Center Beijing Key Laboratory of Cardiometabolic Molecular Medicine Peking University 100871 Beijing China
- Academy for Advanced Interdisciplinary Studies Peking University 100871 Beijing China
- Peking-Tsinghua Center for Life Science Peking University 100871 Beijing China
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