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Johnson SC, Annamdevula NS, Leavesley SJ, Francis CM, Rich TC. Hyperspectral imaging and dynamic region of interest tracking approaches to quantify localized cAMP signals. Biochem Soc Trans 2024; 52:191-203. [PMID: 38334148 DOI: 10.1042/bst20230352] [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: 11/15/2023] [Revised: 01/10/2024] [Accepted: 01/15/2024] [Indexed: 02/10/2024]
Abstract
Cyclic adenosine monophosphate (cAMP) is a ubiquitous second messenger known to orchestrate a myriad of cellular functions over a wide range of timescales. In the last 20 years, a variety of single-cell sensors have been developed to measure second messenger signals including cAMP, Ca2+, and the balance of kinase and phosphatase activities. These sensors utilize changes in fluorescence emission of an individual fluorophore or Förster resonance energy transfer (FRET) to detect changes in second messenger concentration. cAMP and kinase activity reporter probes have provided powerful tools for the study of localized signals. Studies relying on these and related probes have the potential to further revolutionize our understanding of G protein-coupled receptor signaling systems. Unfortunately, investigators have not been able to take full advantage of the potential of these probes due to the limited signal-to-noise ratio of the probes and the limited ability of standard epifluorescence and confocal microscope systems to simultaneously measure the distributions of multiple signals (e.g. cAMP, Ca2+, and changes in kinase activities) in real time. In this review, we focus on recently implemented strategies to overcome these limitations: hyperspectral imaging and adaptive thresholding approaches to track dynamic regions of interest (ROI). This combination of approaches increases signal-to-noise ratio and contrast, and allows identification of localized signals throughout cells. These in turn lead to the identification and quantification of intracellular signals with higher effective resolution. Hyperspectral imaging and dynamic ROI tracking approaches offer investigators additional tools with which to visualize and quantify multiplexed intracellular signaling systems.
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Affiliation(s)
- Santina C Johnson
- Department of Pharmacology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
| | - Naga S Annamdevula
- Department of Pharmacology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Department of Physiology and Cell Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
| | - Silas J Leavesley
- Department of Pharmacology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Chemical and Biomolecular Engineering, University of South Alabama, Mobile, AL, U.S.A
| | - C Michael Francis
- Department of Physiology and Cell Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
| | - Thomas C Rich
- Department of Pharmacology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
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Reissaus CA, Day KH, Mirmira RG, Dunn KW, Pavalko FM, Day RN. PIE-FLIM Measurements of Two Different FRET-Based Biosensor Activities in the Same Living Cells. Biophys J 2020; 118:1820-1829. [PMID: 32191861 DOI: 10.1016/j.bpj.2020.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 02/27/2020] [Accepted: 03/02/2020] [Indexed: 12/14/2022] Open
Abstract
We report the use of pulsed interleaved excitation (PIE)-fluorescence lifetime imaging microscopy (FLIM) to measure the activities of two different biosensor probes simultaneously in single living cells. Many genetically encoded biosensors rely on the measurement of Förster resonance energy transfer (FRET) to detect changes in biosensor conformation that accompany the targeted cell signaling event. One of the most robust ways of quantifying FRET is to measure changes in the fluorescence lifetime of the donor fluorophore using FLIM. The study of complex signaling networks in living cells demands the ability to track more than one of these cellular events at the same time. Here, we demonstrate how PIE-FLIM can separate and quantify the signals from different FRET-based biosensors to simultaneously measure changes in the activity of two cell signaling pathways in the same living cells in tissues. The imaging system described here uses selectable laser wavelengths and synchronized detection gating that can be tailored and optimized for each FRET pair. Proof-of-principle studies showing simultaneous measurement of cytosolic calcium and protein kinase A activity are shown, but the PIE-FLIM approach is broadly applicable to other signaling pathways.
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Affiliation(s)
- Christopher A Reissaus
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana; The Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana
| | - Kathleen H Day
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Raghavendra G Mirmira
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana; The Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana
| | - Kenneth W Dunn
- The Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana; Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Fredrick M Pavalko
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana; The Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana
| | - Richard N Day
- The Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana; Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, Indiana.
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Esposito A. How many photons are needed for FRET imaging? Biomed Opt Express 2020; 11:1186-1202. [PMID: 32133242 PMCID: PMC7041441 DOI: 10.1364/boe.379305] [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] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 12/15/2019] [Accepted: 01/21/2020] [Indexed: 06/10/2023]
Abstract
Förster resonance energy transfer (FRET) imaging is an essential analytical method in biomedical research. The limited photon-budget experimentally available, however, imposes compromises between spatiotemporal and biochemical resolutions, photodamage and phototoxicity. The study of photon-statistics in biochemical imaging is thus important in guiding the efficient design of instrumentation and assays. Here, we show a comparative analysis of photon-statistics in FRET imaging demonstrating how the precision of FRET imaging varies vastly with imaging parameters. Therefore, we provide analytical and numerical tools for assay optimization. Fluorescence lifetime imaging microscopy (FLIM) is a very robust technique with excellent photon-efficiencies. However, we show that also intensity-based FRET imaging can reach high precision by utilizing information from both donor and acceptor fluorophores.
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Affiliation(s)
- Alessandro Esposito
- MRC Cancer Unit, University of Cambridge, Biomedical Campus, Cambridge, CB20XY, UK
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Vinogradova TM, Kobrinsky E, Lakatta EG. Dual Activation of Phosphodiesterases 3 and 4 Regulates Basal Spontaneous Beating Rate of Cardiac Pacemaker Cells: Role of Compartmentalization? Front Physiol 2018; 9:1301. [PMID: 30356755 PMCID: PMC6189467 DOI: 10.3389/fphys.2018.01301] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/29/2018] [Indexed: 12/17/2022] Open
Abstract
Spontaneous firing of sinoatrial (SA) node cells (SANCs) is regulated by cyclic adenosine monophosphate (cAMP)-mediated, protein kinase A (PKA)-dependent (cAMP/PKA) local subsarcolemmal Ca2+ releases (LCRs) from ryanodine receptors (RyR). The LCRs occur during diastolic depolarization (DD) and activate an inward Na+/Ca2+ exchange current that accelerates the DD rate prompting the next action potential (AP). Basal phosphodiesterases (PDEs) activation degrades cAMP, reduces basal cAMP/PKA-dependent phosphorylation, and suppresses normal spontaneous firing of SANCs. The cAMP-degrading PDE1, PDE3, and PDE4 represent major PDE activities in rabbit SANC, and PDE inhibition by 3-isobutyl-1-methylxanthine (IBMX) increases spontaneous firing of SANC by ∼50%. Though inhibition of single PDE1–PDE4 only moderately increases spontaneous SANC firing, dual PDE3 + PDE4 inhibition produces a synergistic effect hastening the spontaneous SANC beating rate by ∼50%. Here, we describe the expression and distribution of different PDE subtypes within rabbit SANCs, several specific targets (L-type Ca2+ channels and phospholamban) regulated by basal concurrent PDE3 + PDE4 activation, and critical importance of RyR Ca2+ releases for PDE-dependent regulation of spontaneous SANC firing. Colocalization of PDE3 and PDE4 beneath sarcolemma or in striated patterns inside SANCs strongly suggests that PDE-dependent regulation of cAMP/PKA signaling might be executed at the local level; this idea, however, requires further verification.
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Affiliation(s)
- Tatiana M Vinogradova
- Laboratory of Cardiovascular Science, Intramural Research Program, NIA, NIH, Baltimore, MD, United States
| | - Evgeny Kobrinsky
- Laboratory of Cardiovascular Science, Intramural Research Program, NIA, NIH, Baltimore, MD, United States
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, NIA, NIH, Baltimore, MD, United States
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