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Mukherjee S, Klarenbeek J, El Oualid F, van den Broek B, Jalink K. "Radical" differences between two FLIM microscopes affect interpretation of cell signaling dynamics. iScience 2024; 27:110268. [PMID: 39036041 PMCID: PMC11257777 DOI: 10.1016/j.isci.2024.110268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 02/12/2024] [Accepted: 06/11/2024] [Indexed: 07/23/2024] Open
Abstract
The outcome of cell signaling depends not only on signal strength but also on temporal progression. We use Fluorescence Lifetime Imaging of Resonance Energy Transfer (FLIM/FRET) biosensors to investigate intracellular signaling dynamics. We examined the β1 receptor-Gαs-cAMP signaling axis using both widefield frequency domain FLIM (fdFLIM) and fast confocal time-correlated single photon counting (TCSPC) setups. Unexpectedly, we observed that fdFLIM revealed transient cAMP responses in HeLa and Cos7 cells, contrasting with sustained responses as detected with TCSPC. Investigation revealed no light-induced effects on cAMP generation or breakdown. Rather, folic acid present in the imaging medium appeared to be the culprit, as its excitation with blue light sensitized degradation of β1 agonists. Our findings highlight the impact of subtle phototoxicity on experimental outcomes, advocating confocal TCSPC for reliable analysis of response kinetics and stressing the need for full disclosure of chemical formulations by scientific vendors.
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Affiliation(s)
- Sravasti Mukherjee
- Department of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066CX, the Netherlands
- Swammerdam Institute of Life Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098 XH, the Netherlands
| | - Jeffrey Klarenbeek
- Department of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066CX, the Netherlands
| | - Farid El Oualid
- UbiQ Bio B.V., Science Park 301, Amsterdam 1098 XH, the Netherlands
| | - Bram van den Broek
- Department of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066CX, the Netherlands
- BioImaging Facility, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066CX, the Netherlands
| | - Kees Jalink
- Department of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066CX, the Netherlands
- Swammerdam Institute of Life Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098 XH, the Netherlands
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Mandrou E, Thomason PA, Paschke PI, Paul NR, Tweedy L, Insall RH. A Reliable System for Quantitative G-Protein Activation Imaging in Cancer Cells. Cells 2024; 13:1114. [PMID: 38994966 PMCID: PMC11240385 DOI: 10.3390/cells13131114] [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: 04/28/2024] [Revised: 06/13/2024] [Accepted: 06/20/2024] [Indexed: 07/13/2024] Open
Abstract
Fluorescence resonance energy transfer (FRET) biosensors have proven to be an indispensable tool in cell biology and, more specifically, in the study of G-protein signalling. The best method of measuring the activation status or FRET state of a biosensor is often fluorescence lifetime imaging microscopy (FLIM), as it does away with many disadvantages inherent to fluorescence intensity-based methods and is easily quantitated. Despite the significant potential, there is a lack of reliable FLIM-FRET biosensors, and the data processing and analysis workflows reported previously face reproducibility challenges. Here, we established a system in live primary mouse pancreatic ductal adenocarcinoma cells, where we can detect the activation of an mNeonGreen-Gαi3-mCherry-Gγ2 biosensor through the lysophosphatidic acid receptor (LPAR) with 2-photon time-correlated single-photon counting (TCSPC) FLIM. This combination gave a superior signal to the commonly used mTurquoise2-mVenus G-protein biosensor. This system has potential as a platform for drug screening, or to answer basic cell biology questions in the field of G-protein signalling.
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Affiliation(s)
- Elena Mandrou
- CRUK Scotland Institute, Garscube Campus, Glasgow G61 1BD, UK
| | | | | | - Nikki R. Paul
- CRUK Scotland Institute, Garscube Campus, Glasgow G61 1BD, UK
| | - Luke Tweedy
- School of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Robert H. Insall
- CRUK Scotland Institute, Garscube Campus, Glasgow G61 1BD, UK
- School of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK
- Division of Cell & Developmental Biology, University College London, London WC1E 6BT, UK
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Fessl T, Majellaro M, Bondar A. Microscopy and spectroscopy approaches to study GPCR structure and function. Br J Pharmacol 2023. [PMID: 38087925 DOI: 10.1111/bph.16297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 11/03/2023] [Accepted: 11/30/2023] [Indexed: 01/05/2024] Open
Abstract
The GPCR signalling cascade is a key pathway responsible for the signal transduction of a multitude of physical and chemical stimuli, including light, odorants, neurotransmitters and hormones. Understanding the structural and functional properties of the GPCR cascade requires direct observation of signalling processes in high spatial and temporal resolution, with minimal perturbation to endogenous systems. Optical microscopy and spectroscopy techniques are uniquely suited to this purpose because they excel at multiple spatial and temporal scales and can be used in living objects. Here, we review recent developments in microscopy and spectroscopy technologies which enable new insights into GPCR signalling. We focus on advanced techniques with high spatial and temporal resolution, single-molecule methods, labelling strategies and approaches suitable for endogenous systems and large living objects. This review aims to assist researchers in choosing appropriate microscopy and spectroscopy approaches for a variety of applications in the study of cellular signalling.
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Affiliation(s)
- Tomáš Fessl
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | | | - Alexey Bondar
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Laboratory of Microscopy and Histology, Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic
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Vu CQ, Arai S. Quantitative Imaging of Genetically Encoded Fluorescence Lifetime Biosensors. BIOSENSORS 2023; 13:939. [PMID: 37887132 PMCID: PMC10605767 DOI: 10.3390/bios13100939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 10/28/2023]
Abstract
Genetically encoded fluorescence lifetime biosensors have emerged as powerful tools for quantitative imaging, enabling precise measurement of cellular metabolites, molecular interactions, and dynamic cellular processes. This review provides an overview of the principles, applications, and advancements in quantitative imaging with genetically encoded fluorescence lifetime biosensors using fluorescence lifetime imaging microscopy (go-FLIM). We highlighted the distinct advantages of fluorescence lifetime-based measurements, including independence from expression levels, excitation power, and focus drift, resulting in robust and reliable measurements compared to intensity-based approaches. Specifically, we focus on two types of go-FLIM, namely Förster resonance energy transfer (FRET)-FLIM and single-fluorescent protein (FP)-based FLIM biosensors, and discuss their unique characteristics and benefits. This review serves as a valuable resource for researchers interested in leveraging fluorescence lifetime imaging to study molecular interactions and cellular metabolism with high precision and accuracy.
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Affiliation(s)
- Cong Quang Vu
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Satoshi Arai
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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Rebenku I, Lloyd CB, Szöllősi J, Vereb G. Pixel-by-pixel autofluorescence corrected FRET in fluorescence microscopy improves accuracy for samples with spatially varied autofluorescence to signal ratio. Sci Rep 2023; 13:2934. [PMID: 36804608 PMCID: PMC9941493 DOI: 10.1038/s41598-023-30098-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 02/14/2023] [Indexed: 02/22/2023] Open
Abstract
The actual interaction between signaling species in cellular processes is often more important than their expression levels. Förster resonance energy transfer (FRET) is a popular tool for studying molecular interactions, since it is highly sensitive to proximity in the range of 2-10 nm. Spectral spillover-corrected quantitative (3-cube) FRET is a cost effective and versatile approach, which can be applied in flow cytometry and various modalities of fluorescence microscopy, but may be hampered by varying levels of autofluorescence. Here, we have implemented pixel-by-pixel autofluorescence correction in microscopy FRET measurements, exploiting cell-free calibration standards void of autofluorescence that allow the correct determination of all spectral spillover factors. We also present an ImageJ/Fiji plugin for interactive analysis of single images as well as automatic creation of quantitative FRET efficiency maps from large image sets. For validation, we used bead and cell based FRET models covering a range of signal to autofluorescence ratios and FRET efficiencies and compared the approach with conventional average autofluorescence/background correction. Pixel-by-pixel autofluorescence correction proved to be superior in the accuracy of results, particularly for samples with spatially varying autofluorescence and low fluorescence to autofluorescence ratios, the latter often being the case for physiological expression levels.
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Affiliation(s)
- István Rebenku
- grid.7122.60000 0001 1088 8582Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen, 4032 Hungary ,grid.7122.60000 0001 1088 8582ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen, 4032 Hungary
| | - Cameron B. Lloyd
- grid.7122.60000 0001 1088 8582Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen, 4032 Hungary
| | - János Szöllősi
- grid.7122.60000 0001 1088 8582Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen, 4032 Hungary ,grid.7122.60000 0001 1088 8582ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen, 4032 Hungary
| | - György Vereb
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary. .,ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary. .,Faculty of Pharmacy, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary.
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Sheu SH, Upadhyayula S, Dupuy V, Pang S, Deng F, Wan J, Walpita D, Pasolli HA, Houser J, Sanchez-Martinez S, Brauchi SE, Banala S, Freeman M, Xu CS, Kirchhausen T, Hess HF, Lavis L, Li Y, Chaumont-Dubel S, Clapham DE. A serotonergic axon-cilium synapse drives nuclear signaling to alter chromatin accessibility. Cell 2022; 185:3390-3407.e18. [PMID: 36055200 PMCID: PMC9789380 DOI: 10.1016/j.cell.2022.07.026] [Citation(s) in RCA: 68] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 05/16/2022] [Accepted: 07/25/2022] [Indexed: 12/27/2022]
Abstract
Chemical synapses between axons and dendrites mediate neuronal intercellular communication. Here, we describe a synapse between axons and primary cilia: the axo-ciliary synapse. Using enhanced focused ion beam-scanning electron microscopy on samples with optimally preserved ultrastructure, we discovered synapses between brainstem serotonergic axons and the primary cilia of hippocampal CA1 pyramidal neurons. Functionally, these cilia are enriched in a ciliary-restricted serotonin receptor, the 5-hydroxytryptamine receptor 6 (5-HTR6). Using a cilia-targeted serotonin sensor, we show that opto- and chemogenetic stimulation of serotonergic axons releases serotonin onto cilia. Ciliary 5-HTR6 stimulation activates a non-canonical Gαq/11-RhoA pathway, which modulates nuclear actin and increases histone acetylation and chromatin accessibility. Ablation of this pathway reduces chromatin accessibility in CA1 pyramidal neurons. As a signaling apparatus with proximity to the nucleus, axo-ciliary synapses short circuit neurotransmission to alter the postsynaptic neuron's epigenetic state.
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Affiliation(s)
- Shu-Hsien Sheu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; Harvard Medical School, Boston, MA, USA; Boston Children's Hospital, Department of Pathology, Boston, MA, USA; Howard Huges Medical Institute, Boston Children's Hospital, Department of Cardiology, Boston, MA, USA.
| | - Srigokul Upadhyayula
- Advanced Bioimaging Center, University of California at Berkeley, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, USA; Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Vincent Dupuy
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Song Pang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Fei Deng
- School of Life Sciences, Peking University, Beijing, China
| | - Jinxia Wan
- School of Life Sciences, Peking University, Beijing, China
| | - Deepika Walpita
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - H Amalia Pasolli
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Justin Houser
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | | | - Sebastian E Brauchi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; Department of Physiology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile; Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Valdivia, Chile
| | - Sambashiva Banala
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Melanie Freeman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - C Shan Xu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Tom Kirchhausen
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, 200 Longwood Ave, Boston, MA, USA; Department of Pediatrics, Harvard Medical School, 200 Longwood Ave, Boston, MA, USA
| | - Harald F Hess
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Luke Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Yulong Li
- School of Life Sciences, Peking University, Beijing, China
| | - Séverine Chaumont-Dubel
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - David E Clapham
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA; Harvard Medical School, Boston, MA, USA; Howard Huges Medical Institute, Boston Children's Hospital, Department of Cardiology, Boston, MA, USA.
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