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Márquez-Nogueras KM, Bovo E, Neczypor JE, Cao Q, Zima AV, Kuo IY. Utilization of the genetically encoded calcium indicator Salsa6F in cardiac applications. Cell Calcium 2024; 119:102873. [PMID: 38537433 PMCID: PMC11018326 DOI: 10.1016/j.ceca.2024.102873] [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: 12/05/2023] [Revised: 02/23/2024] [Accepted: 03/13/2024] [Indexed: 04/05/2024]
Abstract
Calcium signaling is a critical process required for cellular mechanisms such as cardiomyocyte contraction. The inability of the cell to properly activate or regulate calcium signaling can lead to contractile dysfunction. In isolated cardiomyocytes, calcium signaling has been primarily studied using calcium fluorescent dyes, however these dyes have limited applicability to whole organs. Here, we crossed the Salsa6f mouse which expresses a genetically encoded ratiometric cytosolic calcium indicator with a cardiomyocyte specific inducible cre to temporally-induce expression and studied cytosolic calcium transients in isolated cardiomyocytes and modified Langendorff heart preparations. Isolated cardiomyocytes expressing Salsa6f or Fluo-4AM loaded were compared. We also crossed the Salsa6f mouse with a floxed Polycystin 2 (PC2) mouse to test the feasibility of using the Salsa6f mouse to measure calcium transients in PC2 heterozygous or homozygous knock out mice. Although there are caveats in the applicability of the Salsa6f mouse, there are clear advantages to using the Salsa6f mouse to measure whole heart calcium signals.
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Affiliation(s)
- Karla M Márquez-Nogueras
- Department of Cell and Molecular Physiology, and Cardiovascular Research Institute, Stritch School of Medicine, Loyola University Chicago, 2160 S. First Ave, Maywood, IL, USA
| | - Elisa Bovo
- Department of Cell and Molecular Physiology, and Cardiovascular Research Institute, Stritch School of Medicine, Loyola University Chicago, 2160 S. First Ave, Maywood, IL, USA
| | - Jacy E Neczypor
- Department of Cell and Molecular Physiology, and Cardiovascular Research Institute, Stritch School of Medicine, Loyola University Chicago, 2160 S. First Ave, Maywood, IL, USA
| | - Quan Cao
- Department of Cell and Molecular Physiology, and Cardiovascular Research Institute, Stritch School of Medicine, Loyola University Chicago, 2160 S. First Ave, Maywood, IL, USA
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, and Cardiovascular Research Institute, Stritch School of Medicine, Loyola University Chicago, 2160 S. First Ave, Maywood, IL, USA
| | - Ivana Y Kuo
- Department of Cell and Molecular Physiology, and Cardiovascular Research Institute, Stritch School of Medicine, Loyola University Chicago, 2160 S. First Ave, Maywood, IL, USA.
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Pereira CG, Andrade J, Ranquine T, de Moura IN, da Rocha RA, Furtado MAM, Bell MJV, Anjos V. Characterization and detection of adulterated whey protein supplements using stationary and time-resolved fluorescence spectroscopy. Lebensm Wiss Technol 2018. [DOI: 10.1016/j.lwt.2018.06.050] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Xanthines Studied via Femtosecond Fluorescence Spectroscopy. Molecules 2016; 21:molecules21121668. [PMID: 27918492 PMCID: PMC6274292 DOI: 10.3390/molecules21121668] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/25/2016] [Accepted: 11/29/2016] [Indexed: 11/30/2022] Open
Abstract
Xanthines represent a wide class of compounds closely related to the DNA bases adenine and guanine. Ubiquitous in the human body, they are capable of replacing natural bases in double helices and give rise to four-stranded structures. Although the use of their fluorescence for analytical purposes was proposed, their fluorescence properties have not been properly characterized so far. The present paper reports the first fluorescence study of xanthine solutions relying on femtosecond spectroscopy. Initially, we focus on 3-methylxanthine, showing that this compound exhibits non-exponential fluorescence decays with no significant dependence on the emission wavelength. The fluorescence quantum yield (3 × 10−4) and average decay time (0.9 ps) are slightly larger than those found for the DNA bases. Subsequently, we compare the dynamical fluorescence properties of seven mono-, di- and tri-methylated derivatives. Both the fluorescence decays and fluorescence anisotropies vary only weakly with the site and the degree of methylation. These findings are in line with theoretical predictions suggesting the involvement of several conical intersections in the relaxation of the lowest singlet excited state.
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Saleem H, Tovey SC, Molinski TF, Taylor CW. Interactions of antagonists with subtypes of inositol 1,4,5-trisphosphate (IP3) receptor. Br J Pharmacol 2014; 171:3298-312. [PMID: 24628114 PMCID: PMC4080982 DOI: 10.1111/bph.12685] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/26/2014] [Accepted: 03/05/2014] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND AND PURPOSE Inositol 1,4,5-trisphosphate receptors (IP3 Rs) are intracellular Ca(2+) channels. Interactions of the commonly used antagonists of IP3Rs with IP3R subtypes are poorly understood. EXPERIMENTAL APPROACH IP3-evoked Ca(2+) release from permeabilized DT40 cells stably expressing single subtypes of mammalian IP3R was measured using a luminal Ca(2+) indicator. The effects of commonly used antagonists on IP3-evoked Ca(2+) release and (3) H-IP3 binding were characterized. KEY RESULTS Functional analyses showed that heparin was a competitive antagonist of all IP3R subtypes with different affinities for each (IP3R3 > IP3R1 ≥ IP3R2). This sequence did not match the affinities for heparin binding to the isolated N-terminal from each IP3R subtype. 2-aminoethoxydiphenyl borate (2-APB) and high concentrations of caffeine selectively inhibited IP3R1 without affecting IP3 binding. Neither Xestospongin C nor Xestospongin D effectively inhibited IP3-evoked Ca(2+) release via any IP3R subtype. CONCLUSIONS AND IMPLICATIONS Heparin competes with IP3, but its access to the IP3-binding core is substantially hindered by additional IP3R residues. These interactions may contribute to its modest selectivity for IP3R3. Practicable concentrations of caffeine and 2-APB inhibit only IP3R1. Xestospongins do not appear to be effective antagonists of IP3Rs.
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Affiliation(s)
- Huma Saleem
- Department of Pharmacology, University of CambridgeCambridge, UK
| | - Stephen C Tovey
- Department of Pharmacology, University of CambridgeCambridge, UK
| | | | - Colin W Taylor
- Department of Pharmacology, University of CambridgeCambridge, UK
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Limpitikul WB, Dick IE, Joshi-Mukherjee R, Overgaard MT, George AL, Yue DT. Calmodulin mutations associated with long QT syndrome prevent inactivation of cardiac L-type Ca(2+) currents and promote proarrhythmic behavior in ventricular myocytes. J Mol Cell Cardiol 2014; 74:115-24. [PMID: 24816216 DOI: 10.1016/j.yjmcc.2014.04.022] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 04/28/2014] [Indexed: 01/13/2023]
Abstract
Recent work has identified missense mutations in calmodulin (CaM) that are associated with severe early-onset long-QT syndrome (LQTS), leading to the proposition that altered CaM function may contribute to the molecular etiology of this subset of LQTS. To date, however, no experimental evidence has established these mutations as directly causative of LQTS substrates, nor have the molecular targets of CaM mutants been identified. Here, therefore, we test whether expression of CaM mutants in adult guinea-pig ventricular myocytes (aGPVM) induces action-potential prolongation, and whether affiliated alterations in the Ca(2+) regulation of L-type Ca(2+) channels (LTCC) might contribute to such prolongation. In particular, we first overexpressed CaM mutants in aGPVMs, and observed both increased action potential duration (APD) and heightened Ca(2+) transients. Next, we demonstrated that all LQTS CaM mutants have the potential to strongly suppress Ca(2+)/CaM-dependent inactivation (CDI) of LTCCs, whether channels were heterologously expressed in HEK293 cells, or present in native form within myocytes. This attenuation of CDI is predicted to promote action-potential prolongation and boost Ca(2+) influx. Finally, we demonstrated how a small fraction of LQTS CaM mutants (as in heterozygous patients) would nonetheless suffice to substantially diminish CDI, and derange electrical and Ca(2+) profiles. In all, these results highlight LTCCs as a molecular locus for understanding and treating CaM-related LQTS in this group of patients.
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Affiliation(s)
- Worawan B Limpitikul
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ivy E Dick
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Rosy Joshi-Mukherjee
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Michael T Overgaard
- Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Denmark
| | - Alfred L George
- Department of Medicine, Vanderbilt University, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205; Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205.
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Alves JCL, Poppi RJ. Pharmaceutical analysis in solids using front face fluorescence spectroscopy and multivariate calibration with matrix correction by piecewise direct standardization. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 103:311-318. [PMID: 23261628 DOI: 10.1016/j.saa.2012.10.074] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 10/29/2012] [Accepted: 10/31/2012] [Indexed: 06/01/2023]
Abstract
This paper reports the application of piecewise direct standardization (PDS) for matrix correction in front face fluorescence spectroscopy of solids when different excipients are used in a pharmaceutical preparation based on a mixture of acetylsalicylic acid (ASA), paracetamol (acetaminophen) and caffeine. As verified in earlier studies, the use of different excipients and their ratio can cause a displacement, change in fluorescence intensity or band profile. To overcome this important drawback, a standardization strategy was adopted to convert all the excitation-emission fluorescence spectra into those used for model development. An excitation-emission matrix (EEM) for which excitation and emission wavelengths ranging from 265 to 405 nm and 300 to 480 nm, respectively, was used. Excellent results were obtained using unfolded partial least squares (U-PLS), with RMSEP values of 8.2 mg/g, 10.9 mg/g and 2.7 mg/g for ASA, paracetamol and caffeine, respectively, and with relative errors lesser than 5% for the three analytes.
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Affiliation(s)
- Julio Cesar L Alves
- Institute of Chemistry, State University of Campinas-UNICAMP, PO Box 6154, 13083-970 Campinas, SP, Brazil.
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Chen J, Kohler B. Ultrafast nonradiative decay by hypoxanthine and several methylxanthines in aqueous and acetonitrile solution. Phys Chem Chem Phys 2012; 14:10677-82. [DOI: 10.1039/c2cp41296a] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Alves JCL, Poppi RJ. Simultaneous determination of acetylsalicylic acid, paracetamol and caffeine using solid-phase molecular fluorescence and parallel factor analysis. Anal Chim Acta 2009; 642:212-6. [DOI: 10.1016/j.aca.2008.10.067] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 10/23/2008] [Accepted: 10/24/2008] [Indexed: 10/21/2022]
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Launikonis BS, Ríos E. Store-operated Ca2+ entry during intracellular Ca2+ release in mammalian skeletal muscle. J Physiol 2007; 583:81-97. [PMID: 17569733 PMCID: PMC2277221 DOI: 10.1113/jphysiol.2007.135046] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Store-operated Ca2+ entry (SOCE) is activated following the depletion of internal Ca2+ stores in virtually all eukaryotic cells. Shifted excitation and emission ratioing of fluorescence (SEER) was used to image mag-indo-1 trapped in the tubular (t) system of mechanically skinned rat skeletal muscle fibres to measure SOCE during intracellular Ca2+ release. Cytosolic Ca2+ transients were simultaneously imaged using the fluorescence of rhod-2. Spatially and temporally resolved images of t system [Ca2+] ([Ca2+]t-sys) allowed estimation of Ca2+ entry flux from the rate of decay of [Ca2+]t-sys. Ca2+ release was induced pharmacologically to activate SOCE without voltage-dependent contributions to Ca2+ flux. Inward Ca2+ flux was monotonically dependent on the [Ca2+] gradient, and strongly dependent on the transmembrane potential. The activation of SOCE was controlled locally. It could occur without full Ca2+ store depletion and in less than a second after initiation of store depletion. These results indicate that the molecular agonists of SOCE must be evenly distributed throughout the junctional membranes and can activate rapidly. Termination of SOCE required a net increase in [Ca2+]SR. Activation and termination of SOCE are also demonstrated, for the first time, during a single event of Ca2+ release. At the physiological [Ca2+]t-sys, near 2 mM (relative to t system volume), SOCE flux relative to accessible cytoplasmic volume was at least 18.6 microM s(-1), consistent with times of SR refilling of 1-2 min measured in intact muscle fibres.
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Affiliation(s)
- Bradley S Launikonis
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL 60612, USA.
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Peng S, Publicover NG, Kargacin GJ, Duan D, Airey JA, Sutko JL. Imaging single cardiac ryanodine receptor Ca2+ fluxes in lipid bilayers. Biophys J 2004; 86:134-44. [PMID: 14695257 PMCID: PMC1303777 DOI: 10.1016/s0006-3495(04)74091-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In this and an accompanying report we describe two steps, single-channel imaging and channel immobilization, necessary for using optical imaging to analyze the function of ryanodine receptor (RyR) channels reconstituted in lipid bilayers. An optical bilayer system capable of laser scanning confocal imaging of fluo-3 fluorescence due to Ca2+ flux through single RyR2 channels and simultaneous recording of single channel currents was developed. A voltage command protocol was devised in which the amplitude, time course, shape, and hence the quantity of Ca2+ flux through a single RyR2 channel is controlled solely by the voltage imposed across the bilayer. Using this system, the voltage command protocol, and concentrations of Ca2+ (25-50 mM) that result in saturating RyR2 Ca2+ currents, proportional fluo-3 fluorescence was recorded simultaneously with Ca2+ currents having amplitudes of 0.25-14 pA. Ca2+ sparks, similar to those obtained with conventional microscope-based laser scanning confocal systems, were imaged in mouse ventricular cardiomyocytes using the optical bilayer system. The utility of the optical bilayer for systematic investigation of how cellular factors extrinsic to the RyR2 channel, such as Ca2+ buffers and diffusion, alter fluo-3 fluorescent responses to RyR2 Ca2+ currents, and for addressing other current research questions is discussed.
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Affiliation(s)
- S Peng
- Department of Pharmacology, University of Nevada, Reno, Nevada 89557, USA
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Leroy J, Lignon JM, Gannier F, Argibay JA, Malécot CO. Caffeine-induced immobilization of gating charges in isolated guinea-pig ventricular heart cells. Br J Pharmacol 2002; 135:721-34. [PMID: 11834620 PMCID: PMC1573184 DOI: 10.1038/sj.bjp.0704520] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The effects of 10 mM caffeine (CAF) on intramembrane charge movements (ICM) were studied in isolated guinea-pig ventricular heart cells with the whole-cell patch-clamp technique. In the presence of CAF, the properties (voltage dependence, maximum Q(ON) [Q(max)], availability with voltage) of Q(ON) charge activated from -110 mV were barely affected. Following a 100 ms prepulse to -50 mV to decrease the participation of charges originating from Na channels, the voltage dependence of Q(ON) was shifted by 5 mV (negative component) and by 10 mV (positive component) towards negative potentials, and Q(max) was depressed by 16.5%. CAF drastically reduced in a time- and voltage-dependent manner Q(OFF) on repolarization to -50 mV, the effects being greater at positive potentials. CAF-induced Q(OFF) immobilization could be almost entirely removed by repolarization to voltages as negative as -170 mV. In these conditions, the voltage-dependence of Q(OFF) (repolarization to +30 to -170 mV) was shifted by 17 mV (negative component) and 30 mV (positive component) towards negative potentials, suggesting an interconversion into charge 2. Most of CAF effects were suppressed when the sarcoplasmic reticulum (SR) was not functional or when the cells were loaded with BAPTA-AM. We conclude that CAF effects on ICM are likely due to Ca(2+) ions released from the SR, and which accumulate in the subsarcolemmal fuzzy spaces in the vicinity of the Ca channels. Because CAF effects were more pronounced on Q(OFF) than on Q(ON) the channels have likely to open before Ca(2+) ions could affect their gating properties. It is speculated that such an effect on gating charges might contribute to the Ca-induced inactivation of the Ca current.
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Affiliation(s)
- Jérôme Leroy
- CNRS UMR 6542, Physiologie des Cellules Cardiaques et Vasculaires, Faculté des Sciences, Parc de Grandmont, 37200 Tours, France
| | - Jacques M Lignon
- CNRS UMR 6542, Physiologie des Cellules Cardiaques et Vasculaires, Faculté des Sciences, Parc de Grandmont, 37200 Tours, France
| | - François Gannier
- CNRS UMR 6542, Physiologie des Cellules Cardiaques et Vasculaires, Faculté des Sciences, Parc de Grandmont, 37200 Tours, France
| | - Jorge A Argibay
- CNRS UMR 6542, Physiologie des Cellules Cardiaques et Vasculaires, Faculté des Sciences, Parc de Grandmont, 37200 Tours, France
| | - Claire O Malécot
- CNRS UMR 6542, Physiologie des Cellules Cardiaques et Vasculaires, Faculté des Sciences, Parc de Grandmont, 37200 Tours, France
- Author for correspondence:
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Treves S, Pouliquin R, Moccagatta L, Zorzato F. Functional properties of EGFP-tagged skeletal muscle calcium-release channel (ryanodine receptor) expressed in COS-7 cells: sensitivity to caffeine and 4-chloro-m-cresol. Cell Calcium 2002; 31:1-12. [PMID: 11990295 DOI: 10.1054/ceca.2001.0252] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We constructed and expressed in COS-7 cells, three E-green fluorescent protein (EGFP) tagged recombinant skeletal muscle ryanodine receptors (RYR). EGFP was tagged to (i) the NH2-terminus (nEGFP-RYR(FL)) and to (ii) the COOH-terminus (cRYR(FL)-EGFP) of the full length RYR; we also tagged the EGFP to (iii) the NH2-terminus of a truncated version of the RYR (nEGFP-RYR(Bhat)) lacking the bulk of the protein. The fluorescent pattern EGFP with all three constructs colocalize with that of an endoplasmic reticulum (ER) membrane tracker fluorescent dye, indicating that the RYR constructs are targeted to ER membranes. Our results show that: (i) COOH-terminal tagging abolishes the sensitivity of the RYR to caffeine, whereas the presence of EGFP at the NH2-terminus does not affect caffeine sensitivity and (ii) 4-Cl-m-cresol sensitivity is lost both with the truncated nEGFP-RYR(Bhat) and the nEGFP-RYR(FL), while COOH-terminal tagging does not affect sensitivity to 4-chloro-m-cresol. The dose-response curves of caffeine-induced calcium release of nEGFP-RYR(FL) differ from those of the truncated nEGFP-RYR(Bhat). Maximal calcium release was approached at 10 mM caffeine with the nEGFP-RYR(FL), while cells expressing the nEGFP-RYR(Bhat) construct displayed a bell shaped curve and the maximal concentration for caffeine-induced calcium release was 5 mM. Equilibrium [3H]-ryanodine binding confirmed the calcium photometry data. Our results demonstrate that EGFP tagging modifies the pharmacological properties of RYR, and suggest that 4-chloro-m-cresol and caffeine act through different mechanisms and probably interact with different sites on the RYR calcium release channel.
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Affiliation(s)
- S Treves
- Department of Anesthesiology, Kantonsspital Basel, Switzerland.
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