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Arena DT, Hofer AM. Imaging the cAMP Signaling Microdomain of the Primary Cilium Using Targeted FRET-Based Biosensors. Methods Mol Biol 2022; 2483:77-92. [PMID: 35286670 DOI: 10.1007/978-1-0716-2245-2_5] [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] [Indexed: 06/14/2023]
Abstract
Optical approaches have revolutionized our view of second messenger signaling in organelles, allowing precise time-resolved assessment of soluble signaling molecules in situ. Among the most challenging of subcellular signaling microdomains to assay is the primary cilium. A petite but visually arresting organelle, the primary cilium extends from the cell surface of most non-dividing cells. Recently, the concept of the primary cilium as an independent cAMP signaling organelle has attracted substantial interest. The cilium sequesters a very specific subset of ciliary cAMP-linked GPCRs in its membrane (e.g., 5-HT6, D1R, MCR4, FFAR4, TGR5), as well as other key components of the cAMP signaling machinery that include adenylyl cyclases, GNAS, phosphodiesterases, PKA holoenzyme, and biologically important PKA targets. Here we provide a practical guide to assessing ciliary cAMP signals in live cells using targeted genetically encoded FRET biosensors. Key experimental difficulties include gathering sufficient signal from such a small, photon-limited volume, and the susceptibility of cilia to movement artifacts. Other challenges are associated with the fidelity of sensor targeting and the difficulties in distinguishing between cAMP signals produced exclusively within the cilium vs. those that emanate from the cell body. Here we describe ratio imaging approaches used in our lab for time-resolved visualization of ciliary cAMP in cultured renal cells. These methods can be readily adapted to other cell types and microscopy platforms according to the needs of the user.
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Affiliation(s)
- Danielle T Arena
- VA Boston Healthcare System and the Department of Surgery, Brigham & Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Aldebaran M Hofer
- VA Boston Healthcare System and the Department of Surgery, Brigham & Women's Hospital, Harvard Medical School, Boston, MA, USA.
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Koschinski A, Zaccolo M. Micro-2D Cell Culture for cAMP Measurements Using FRET Reporters in Human iPSC-Derived Cardiomyocytes. Methods Mol Biol 2022; 2483:141-165. [PMID: 35286674 DOI: 10.1007/978-1-0716-2245-2_9] [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] [Indexed: 06/14/2023]
Abstract
In the last years human induced pluripotent stem cell-derived cardiomyocytes (hIPS-CMs) have emerged as a promising alternative to rodent-derived cardiomyocytes. However, as the differentiation process is lengthy and commercially available cells are expensive, the cell number is limited. Here we provide detailed information on how to scale down 2D cell cultures of hIPS-CMs for the purpose of cAMP FRET measurements, thereby extending the number of possible experiments by more than tenfold. Crucial factors like cell density or cell number to culturing media volume can be maintained exactly as under normal culturing conditions and existing equipment does not need to be modified.The chapter covers the preparation of downscaled cell culture vessels, coating and seeding procedures, transduction or transfection of the cells with a genetically encoded cAMP FRET sensor, performing real-time cAMP FRET measurements with this sensor and the analysis of generated imaging data. Numbers for seeding areas, seeding densities, coating volumes and concentrations, media volumes, and concentrations of reagents are given as guidelines.
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Affiliation(s)
- Andreas Koschinski
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Muller GK, Song J, Jani V, Wu Y, Liu T, Jeffreys WPD, O’Rourke B, Anderson ME, Kass DA. PDE1 Inhibition Modulates Ca v1.2 Channel to Stimulate Cardiomyocyte Contraction. Circ Res 2021; 129:872-886. [PMID: 34521216 PMCID: PMC8553000 DOI: 10.1161/circresaha.121.319828] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Grace K Muller
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Joy Song
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Vivek Jani
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Yuejin Wu
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Ting Liu
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - William PD Jeffreys
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Brian O’Rourke
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Graduate Program in Cellular and Molecular Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Departments of Pharmacology and Molecular Sciences and Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Mark E Anderson
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Graduate Program in Cellular and Molecular Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - David A Kass
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Graduate Program in Cellular and Molecular Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Departments of Pharmacology and Molecular Sciences and Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
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Massengill CI, Day-Cooney J, Mao T, Zhong H. Genetically encoded sensors towards imaging cAMP and PKA activity in vivo. J Neurosci Methods 2021; 362:109298. [PMID: 34339753 PMCID: PMC8659126 DOI: 10.1016/j.jneumeth.2021.109298] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/22/2021] [Accepted: 07/29/2021] [Indexed: 12/26/2022]
Abstract
Cyclic adenosine monophosphate (cAMP) is a universal second messenger that plays a crucial role in diverse biological functions, ranging from transcription to neuronal plasticity, and from development to learning and memory. In the nervous system, cAMP integrates inputs from many neuromodulators across a wide range of timescales - from seconds to hours - to modulate neuronal excitability and plasticity in brain circuits during different animal behavioral states. cAMP signaling events are both cell-specific and subcellularly compartmentalized. The same stimulus may result in different, sometimes opposite, cAMP dynamics in different cells or subcellular compartments. Additionally, the activity of protein kinase A (PKA), a major cAMP effector, is also spatiotemporally regulated. For these reasons, many laboratories have made great strides toward visualizing the intracellular dynamics of cAMP and PKA. To date, more than 80 genetically encoded sensors, including original and improved variants, have been published. It is starting to become possible to visualize cAMP and PKA signaling events in vivo, which is required to study behaviorally relevant cAMP/PKA signaling mechanisms. Despite significant progress, further developments are needed to enhance the signal-to-noise ratio and practical utility of these sensors. This review summarizes the recent advances and challenges in genetically encoded cAMP and PKA sensors with an emphasis on in vivo imaging in the brain during behavior.
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Affiliation(s)
| | - Julian Day-Cooney
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Tianyi Mao
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
| | - Haining Zhong
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
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Imaging cAMP nanodomains in the heart. Biochem Soc Trans 2020; 47:1383-1392. [PMID: 31670375 PMCID: PMC6824676 DOI: 10.1042/bst20190245] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 10/09/2019] [Accepted: 10/10/2019] [Indexed: 01/13/2023]
Abstract
3′-5′-cyclic adenosine monophosphate (cAMP) is a ubiquitous second messenger that modulates multiple cellular functions. It is now well established that cAMP can mediate a plethora of functional effects via a complex system of local regulatory mechanisms that result in compartmentalized signalling. The use of fluorescent probes to monitor cAMP in intact, living cells have been instrumental in furthering our appreciation of this ancestral and ubiquitous pathway and unexpected details of the nano-architecture of the cAMP signalling network are starting to emerge. Recent evidence shows that sympathetic control of cardiac contraction and relaxation is achieved via generation of multiple, distinct pools of cAMP that lead to differential phosphorylation of target proteins localized only tens of nanometres apart. The specific local control at these nanodomains is enabled by a distinct signalosome where effectors, targets, and regulators of the cAMP signal are clustered. In this review, we focus on recent advances using targeted fluorescent reporters for cAMP and how they have contributed to our current understanding of nanodomain cAMP signalling in the heart. We briefly discuss how this information can be exploited to design novel therapies and we highlight some of the questions that remain unanswered.
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Gadgaard C, Jensen AA. Functional characterization of 5-HT 1A and 5-HT 1B serotonin receptor signaling through G-protein-activated inwardly rectifying K + channels in a fluorescence-based membrane potential assay. Biochem Pharmacol 2020; 175:113870. [PMID: 32088264 DOI: 10.1016/j.bcp.2020.113870] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/18/2020] [Indexed: 11/15/2022]
Abstract
The 5-HT1A and 5-HT1B serotonin receptors are abundantly expressed in the CNS and constitute validated as well as putative drug targets in a variety of psychiatric and cognitive disorders, alcoholism/addiction, pain and migraine. In the present study we have characterized the functional properties of human 5-HT1A and 5-HT1B stably co-expressed with the human G-protein-activated inwardly rectifying K+ channel 2 (GIRK2) in HEK293 cells in the fluorescence-based FLIPR® Membrane Potential Blue (FMP) assay. Serotonin and other agonists induced robust decreases in fluorescence levels in the 5-HT1A/GIRK2- and 5-HT1B/GIRK2-HEK293 cells in a concentration-dependent manner in the assay, and these responses could be inhibited by selective 5-HT1A/5-HT1B antagonists and by the Gαi/o-protein inhibitor pertussis toxin (PTX). Five additional stable HEK293 cell lines co-expressing 5-HT1A or 5-HT1B with GIRK2 and one of the PTX-insensitive Gαi/o-subunit mutants Gαi1C351I, Gαi2C352I and Gαo1C351I were constructed, and 5-HT1A/5-HT1B-mediated responses through these specific Gαi/o-subunits were measured in these cells pretreated with PTX in the FMP assay. The functional properties of 16 reference 5-HT1 agonists were characterized at the seven cell lines, which constitutes the most detailed pharmacological profiling and comparison of 5-HT1A and 5-HT1B receptor signaling in the same assay published to date. We propose that this approach to assay 5-HT1-mediated signaling through endogenous Gαi/o-proteins in HEK293 cells or through specific Gαi/o-subunits in a fairly high-throughput manner holds some advantages to other functional assays for Gαi/o-coupled receptors. The assay will facilitate detailed profiling of the Gαi/o- and Gβγ-mediated signaling of 5-HT1A and 5-HT1B at the molecular level, and it could also be used to identify novel modulators for the receptors.
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Affiliation(s)
- Camilla Gadgaard
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen Ø, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen Ø, Denmark.
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Bers DM, Xiang YK, Zaccolo M. Whole-Cell cAMP and PKA Activity are Epiphenomena, Nanodomain Signaling Matters. Physiology (Bethesda) 2020; 34:240-249. [PMID: 31165682 DOI: 10.1152/physiol.00002.2019] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Novel targeted fluorescent biosensors provide key insights into very local nanodomains of cAMP and PKA activity, and how they respond differently to β-adrenergic activation in cardiac myocytes. This unique spatiotemporal detail in living cells is not available with biochemical measurements of total cellular cAMP and PKA, and provides unique physiological insights.
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Affiliation(s)
- Donald M Bers
- Department of Pharmacology, University of California , Davis, California
| | - Yang K Xiang
- Department of Pharmacology, University of California , Davis, California
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford , Oxford , United Kingdom
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