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Lang D, Ni H, Medvedev RY, Liu F, Alvarez-Baron CP, Tyan L, Turner DGP, Warden A, Morotti S, Schrauth TA, Rickert C, Proenza C, Chanda B, Kamp TJ, Robertson GA, Grandi E, Glukhov AV. Caveolar Compartmentalization is Required for Stable Rhythmicity of Sinus Nodal Cells and is Disrupted in Heart Failure. bioRxiv 2024:2024.04.14.589457. [PMID: 38659841 PMCID: PMC11042225 DOI: 10.1101/2024.04.14.589457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Background Heart rhythm relies on complex interactions between the electrogenic membrane proteins and intracellular Ca 2+ signaling in sinoatrial node (SAN) myocytes; however, the mechanisms underlying the functional organization of the proteins involved in SAN pacemaking and its structural foundation remain elusive. Caveolae are nanoscale, plasma membrane pits that compartmentalize various ion channels and transporters, including those involved in SAN pacemaking, via binding with the caveolin-3 scaffolding protein, however the precise role of caveolae in cardiac pacemaker function is unknown. Our objective was to determine the role of caveolae in SAN pacemaking and dysfunction (SND). Methods In vivo electrocardiogram monitoring, ex vivo optical mapping, in vitro confocal Ca 2+ imaging, immunofluorescent and electron microscopy analysis were performed in wild type, cardiac-specific caveolin-3 knockout, and 8-weeks post-myocardial infarction heart failure (HF) mice. SAN tissue samples from donor human hearts were used for biochemical studies. We utilized a novel 3-dimensional single SAN cell mathematical model to determine the functional outcomes of protein nanodomain-specific localization and redistribution in SAN pacemaking. Results In both mouse and human SANs, caveolae compartmentalized HCN4, Ca v 1.2, Ca v 1.3, Ca v 3.1 and NCX1 proteins within discrete pacemaker signalosomes via direct association with caveolin-3. This compartmentalization positioned electrogenic sarcolemmal proteins near the subsarcolemmal sarcoplasmic reticulum (SR) membrane and ensured fast and robust activation of NCX1 by subsarcolemmal local SR Ca 2+ release events (LCRs), which diffuse across ∼15-nm subsarcolemmal cleft. Disruption of caveolae led to the development of SND via suppression of pacemaker automaticity through a 50% decrease of the L-type Ca 2+ current, a negative shift of the HCN current ( I f ) activation curve, and 40% reduction of Na + /Ca 2+ -exchanger function. These changes significantly decreased the SAN depolarizing force, both during diastolic depolarization and upstroke phase, leading to bradycardia, sinus pauses, recurrent development of SAN quiescence, and significant increase in heart rate lability. Computational modeling, supported by biochemical studies, identified NCX1 redistribution to extra-caveolar membrane as the primary mechanism of SAN pauses and quiescence due to the impaired ability of NCX1 to be effectively activated by LCRs and trigger action potentials. HF remodeling mirrored caveolae disruption leading to NCX1-LCR uncoupling and SND. Conclusions SAN pacemaking is driven by complex protein interactions within a nanoscale caveolar pacemaker signalosome. Disruption of caveolae leads to SND, potentially representing a new dimension of SAN remodeling and providing a newly recognized target for therapy.
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Zhang X, Wu Y, Smith C, Louch WE, Morotti S, Dobrev D, Grandi E, Ni H. Enhanced Ca2+-Driven Arrhythmias in Female Patients with Atrial Fibrillation: Insights from Computational Modeling. bioRxiv 2024:2024.03.04.583217. [PMID: 38496584 PMCID: PMC10942295 DOI: 10.1101/2024.03.04.583217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
BACKGROUND AND AIMS Substantial sex-based differences have been reported in atrial fibrillation (AF), with female patients experiencing worse symptoms, increased complications from drug side effects or ablation, and elevated risk of AF-related stroke and mortality. Recent studies revealed sex-specific alterations in AF-associated Ca2+ dysregulation, whereby female cardiomyocytes more frequently exhibit potentially proarrhythmic Ca2+-driven instabilities compared to male cardiomyocytes. In this study, we aim to gain a mechanistic understanding of the Ca2+-handling disturbances and Ca2+-driven arrhythmogenic events in males vs females and establish their responses to Ca2+-targeted interventions. METHODS AND RESULTS We incorporated known sex differences and AF-associated changes in the expression and phosphorylation of key Ca2+-handling proteins and in ultrastructural properties and dimensions of atrial cardiomyocytes into our recently developed 3D atrial cardiomyocyte model that couples electrophysiology with spatially detailed Ca2+-handling processes. Our simulations of quiescent cardiomyocytes show increased incidence of Ca2+ sparks in female vs male myocytes in AF, in agreement with previous experimental reports. Additionally, our female model exhibited elevated propensity to develop pacing-induced spontaneous Ca2+ releases (SCRs) and augmented beat-to-beat variability in action potential (AP)-elicited Ca2+ transients compared with the male model. Parameter sensitivity analysis uncovered precise arrhythmogenic contributions of each component that was implicated in sex and/or AF alterations. Specifically, increased ryanodine receptor phosphorylation in female AF cardiomyocytes emerged as the major SCR contributor, while reduced L-type Ca2+ current was protective against SCRs for male AF cardiomyocytes. Furthermore, simulations of tentative Ca2+-targeted interventions identified potential strategies to attenuate Ca2+-driven arrhythmogenic events in female atria (e.g., t-tubule restoration, and inhibition of ryanodine receptor and sarcoplasmic/endoplasmic reticulum Ca2+-ATPase), and revealed enhanced efficacy when applied in combination. CONCLUSIONS Our sex-specific computational models of human atrial cardiomyocytes uncover increased propensity to Ca2+-driven arrhythmogenic events in female compared to male atrial cardiomyocytes in AF, and point to combined Ca2+-targeted interventions as promising approaches to treat AF in female patients. Our study establishes that AF treatment may benefit from sex-dependent strategies informed by sex-specific mechanisms.
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Ni H, Grandi E. Computational Modeling of Cardiac Electrophysiology. Methods Mol Biol 2024; 2735:63-103. [PMID: 38038844 DOI: 10.1007/978-1-0716-3527-8_5] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Mathematical modeling and simulation are well-established and powerful tools to integrate experimental data of individual components of cardiac electrophysiology, excitation-contraction coupling, and regulatory signaling pathways, to gain quantitative and mechanistic insight into pathophysiological processes and guide therapeutic strategies. Here, we briefly describe the processes governing cardiac myocyte electrophysiology and Ca2+ handling and their regulation, as well as action potential propagation in tissue. We discuss the models and methods used to describe these phenomena, including procedures for model parameterization and validation, in addition to protocols for model interrogation and analysis and techniques that account for phenotypic variability and parameter uncertainty. Our objective is to provide a summary of basic concepts and approaches as a resource for scientists training in this discipline and for all researchers aiming to gain an understanding of cardiac modeling studies.
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Affiliation(s)
- Haibo Ni
- Department of Pharmacology, University of California, Davis, CA, USA.
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, CA, USA.
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Hellgren KT, Ni H, Morotti S, Grandi E. Predictive Male-to-Female Translation of Cardiac Electrophysiological Response to Drugs. JACC Clin Electrophysiol 2023; 9:2642-2648. [PMID: 37768254 DOI: 10.1016/j.jacep.2023.08.016] [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: 05/15/2023] [Revised: 07/22/2023] [Accepted: 08/14/2023] [Indexed: 09/29/2023]
Abstract
Despite evidence that women are at higher risk of drug-induced torsade de pointes and sudden cardiac death, female sex is vastly underrepresented in cardiovascular research, thus limiting our fundamental understanding of sex-specific arrhythmia mechanisms and our ability to predict arrhythmia propensity. To address this urgent clinical and preclinical need, we developed a quantitative tool that predicts the electrophysiological response to drug administration in female cardiomyocytes starting from data collected in males. We demonstrate the suitability of our translator for sex-specific cardiac safety assessment and include proof-of-concept application of our translator to in vitro and in vivo data.
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Affiliation(s)
- Kim T Hellgren
- Department of Pharmacology, University of California-Davis, Davis, California, USA
| | - Haibo Ni
- Department of Pharmacology, University of California-Davis, Davis, California, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California-Davis, Davis, California, USA.
| | - Eleonora Grandi
- Department of Pharmacology, University of California-Davis, Davis, California, USA.
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Grandi E, Feyza Özgen F, Schmidt S, Poelarends GJ. Enzymatic Oxy- and Amino-Functionalization in Biocatalytic Cascade Synthesis: Recent Advances and Future Perspectives. Angew Chem Int Ed Engl 2023; 62:e202309012. [PMID: 37639631 DOI: 10.1002/anie.202309012] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [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: 06/26/2023] [Revised: 08/27/2023] [Accepted: 08/28/2023] [Indexed: 08/31/2023]
Abstract
Biocatalytic cascades are a powerful tool for building complex molecules containing oxygen and nitrogen functionalities. Moreover, the combination of multiple enzymes in one pot offers the possibility to minimize downstream processing and waste production. In this review, we illustrate various recent efforts in the development of multi-step syntheses involving C-O and C-N bond-forming enzymes to produce high value-added compounds, such as pharmaceuticals and polymer precursors. Both in vitro and in vivo examples are discussed, revealing the respective advantages and drawbacks. The use of engineered enzymes to boost the cascades outcome is also addressed and current co-substrate and cofactor recycling strategies are presented, highlighting the importance of atom economy. Finally, tools to overcome current challenges for multi-enzymatic oxy- and amino-functionalization reactions are discussed, including flow systems with immobilized biocatalysts and cascades in confined nanomaterials.
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Affiliation(s)
- Eleonora Grandi
- Department of Chemical and Pharmaceutical Biology, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Fatma Feyza Özgen
- Department of Chemical and Pharmaceutical Biology, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Sandy Schmidt
- Department of Chemical and Pharmaceutical Biology, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Gerrit J Poelarends
- Department of Chemical and Pharmaceutical Biology, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
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Ni H, Morotti S, Zhang X, Dobrev D, Grandi E. Integrative human atrial modelling unravels interactive protein kinase A and Ca2+/calmodulin-dependent protein kinase II signalling as key determinants of atrial arrhythmogenesis. Cardiovasc Res 2023; 119:2294-2311. [PMID: 37523735 DOI: 10.1093/cvr/cvad118] [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] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/18/2023] [Accepted: 06/05/2023] [Indexed: 08/02/2023] Open
Abstract
AIMS Atrial fibrillation (AF), the most prevalent clinical arrhythmia, is associated with atrial remodelling manifesting as acute and chronic alterations in expression, function, and regulation of atrial electrophysiological and Ca2+-handling processes. These AF-induced modifications crosstalk and propagate across spatial scales creating a complex pathophysiological network, which renders AF resistant to existing pharmacotherapies that predominantly target transmembrane ion channels. Developing innovative therapeutic strategies requires a systems approach to disentangle quantitatively the pro-arrhythmic contributions of individual AF-induced alterations. METHODS AND RESULTS Here, we built a novel computational framework for simulating electrophysiology and Ca2+-handling in human atrial cardiomyocytes and tissues, and their regulation by key upstream signalling pathways [i.e. protein kinase A (PKA), and Ca2+/calmodulin-dependent protein kinase II (CaMKII)] involved in AF-pathogenesis. Populations of atrial cardiomyocyte models were constructed to determine the influence of subcellular ionic processes, signalling components, and regulatory networks on atrial arrhythmogenesis. Our results reveal a novel synergistic crosstalk between PKA and CaMKII that promotes atrial cardiomyocyte electrical instability and arrhythmogenic triggered activity. Simulations of heterogeneous tissue demonstrate that this cellular triggered activity is further amplified by CaMKII- and PKA-dependent alterations of tissue properties, further exacerbating atrial arrhythmogenesis. CONCLUSIONS Our analysis reveals potential mechanisms by which the stress-associated adaptive changes turn into maladaptive pro-arrhythmic triggers at the cellular and tissue levels and identifies potential anti-AF targets. Collectively, our integrative approach is powerful and instrumental to assemble and reconcile existing knowledge into a systems network for identifying novel anti-AF targets and innovative approaches moving beyond the traditional ion channel-based strategy.
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Affiliation(s)
- Haibo Ni
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Xianwei Zhang
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montréal, Canada
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
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7
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Herrera NT, Zhang X, Ni H, Maleckar MM, Heijman J, Dobrev D, Grandi E, Morotti S. Dual effects of the small-conductance Ca 2+-activated K + current on human atrial electrophysiology and Ca 2+-driven arrhythmogenesis: an in silico study. Am J Physiol Heart Circ Physiol 2023; 325:H896-H908. [PMID: 37624096 PMCID: PMC10659325 DOI: 10.1152/ajpheart.00362.2023] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 08/11/2023] [Accepted: 08/11/2023] [Indexed: 08/26/2023]
Abstract
By sensing changes in intracellular Ca2+, small-conductance Ca2+-activated K+ (SK) channels dynamically regulate the dynamics of the cardiac action potential (AP) on a beat-to-beat basis. Given their predominance in atria versus ventricles, SK channels are considered a promising atrial-selective pharmacological target against atrial fibrillation (AF), the most common cardiac arrhythmia. However, the precise contribution of SK current (ISK) to atrial arrhythmogenesis is poorly understood, and may potentially involve different mechanisms that depend on species, heart rates, and degree of AF-induced atrial remodeling. Both reduced and enhanced ISK have been linked to AF. Similarly, both SK channel up- and downregulation have been reported in chronic AF (cAF) versus normal sinus rhythm (nSR) patient samples. Here, we use our multiscale modeling framework to obtain mechanistic insights into the contribution of ISK in human atrial cardiomyocyte electrophysiology. We simulate several protocols to quantify how ISK modulation affects the regulation of AP duration (APD), Ca2+ transient, refractoriness, and occurrence of alternans and delayed afterdepolarizations (DADs). Our simulations show that ISK activation shortens the APD and atrial effective refractory period, limits Ca2+ cycling, and slightly increases the propensity for alternans in both nSR and cAF conditions. We also show that increasing ISK counteracts DAD development by enhancing the repolarization force that opposes the Ca2+-dependent depolarization. Taken together, our results suggest that increasing ISK in human atrial cardiomyocytes could promote reentry while protecting against triggered activity. Depending on the leading arrhythmogenic mechanism, ISK inhibition may thus be a beneficial or detrimental anti-AF strategy.NEW & NOTEWORTHY Using our established framework for human atrial myocyte simulations, we investigated the role of the small-conductance Ca2+-activated K+ current (ISK) in the regulation of cell function and the development of Ca2+-driven arrhythmias. We found that ISK inhibition, a promising atrial-selective pharmacological strategy against atrial fibrillation, counteracts the reentry-promoting abbreviation of atrial refractoriness, but renders human atrial myocytes more vulnerable to delayed afterdepolarizations, thus potentially increasing the propensity for ectopic (triggered) activity.
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Affiliation(s)
- Nathaniel T Herrera
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Xianwei Zhang
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Haibo Ni
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Mary M Maleckar
- Department of Computational Physiology, Simula Research Laboratory, Oslo, Norway
| | - Jordi Heijman
- Department of Cardiology, Faculty of Health, Medicine, and Life Sciences, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Dobromir Dobrev
- Faculty of Medicine, West German Heart and Vascular Center, Institute of Pharmacology, University Duisburg-Essen, Essen, Germany
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, United States
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, California, United States
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8
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Smith CER, Grandi E. Unveiling the intricacies of intracellular Ca 2+ regulation in the heart. Biophys J 2023; 122:3019-3021. [PMID: 37478843 PMCID: PMC10432241 DOI: 10.1016/j.bpj.2023.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/07/2023] [Accepted: 07/07/2023] [Indexed: 07/23/2023] Open
Abstract
Recent studies have provided valuable insight into the key mechanisms contributing to the spatiotemporal regulation of intracellular Ca2+ release and Ca2+ signaling in the heart. In this research highlight, we focus on the latest findings published in Biophysical Journal examining the structural organization of Ca2+ handling proteins and assessing the functional aspects of intracellular Ca2+ regulation in health and the detrimental consequences of Ca2+ dysregulation in disease. These important studies pave the way for future mechanistic investigations and multiscale understanding of Ca2+ signaling in the heart.
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Affiliation(s)
- Charlotte E R Smith
- Department of Pharmacology, University of California Davis, Davis, California.
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California.
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Kervadec A, Kezos J, Ni H, Yu M, Marchant J, Spiering S, Kannan S, Kwon C, Andersen P, Bodmer R, Grandi E, Ocorr K, Colas AR. Multiplatform modeling of atrial fibrillation identifies phospholamban as a central regulator of cardiac rhythm. Dis Model Mech 2023; 16:dmm049962. [PMID: 37293707 PMCID: PMC10387351 DOI: 10.1242/dmm.049962] [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: 10/25/2022] [Accepted: 05/26/2023] [Indexed: 06/10/2023] Open
Abstract
Atrial fibrillation (AF) is a common and genetically inheritable form of cardiac arrhythmia; however, it is currently not known how these genetic predispositions contribute to the initiation and/or maintenance of AF-associated phenotypes. One major barrier to progress is the lack of experimental systems to investigate the effects of gene function on rhythm parameters in models with human atrial and whole-organ relevance. Here, we assembled a multi-model platform enabling high-throughput characterization of the effects of gene function on action potential duration and rhythm parameters using human induced pluripotent stem cell-derived atrial-like cardiomyocytes and a Drosophila heart model, and validation of the findings using computational models of human adult atrial myocytes and tissue. As proof of concept, we screened 20 AF-associated genes and identified phospholamban loss of function as a top conserved hit that shortens action potential duration and increases the incidence of arrhythmia phenotypes upon stress. Mechanistically, our study reveals that phospholamban regulates rhythm homeostasis by functionally interacting with L-type Ca2+ channels and NCX. In summary, our study illustrates how a multi-model system approach paves the way for the discovery and molecular delineation of gene regulatory networks controlling atrial rhythm with application to AF.
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Affiliation(s)
- Anaïs Kervadec
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - James Kezos
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Haibo Ni
- Department of Pharmacology, UC Davis, Davis, CA 95616, USA
| | - Michael Yu
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - James Marchant
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Sean Spiering
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Suraj Kannan
- Johns Hopkins University, Baltimore, MD 21205, USA
| | - Chulan Kwon
- Johns Hopkins University, Baltimore, MD 21205, USA
| | | | - Rolf Bodmer
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | | | - Karen Ocorr
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Alexandre R. Colas
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
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10
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Grandi E, Navedo MF, Saucerman JJ, Bers DM, Chiamvimonvat N, Dixon RE, Dobrev D, Gomez AM, Harraz OF, Hegyi B, Jones DK, Krogh-Madsen T, Murfee WL, Nystoriak MA, Posnack NG, Ripplinger CM, Veeraraghavan R, Weinberg S. Diversity of cells and signals in the cardiovascular system. J Physiol 2023; 601:2547-2592. [PMID: 36744541 PMCID: PMC10313794 DOI: 10.1113/jp284011] [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: 10/28/2022] [Accepted: 01/19/2023] [Indexed: 02/07/2023] Open
Abstract
This white paper is the outcome of the seventh UC Davis Cardiovascular Research Symposium on Systems Approach to Understanding Cardiovascular Disease and Arrhythmia. This biannual meeting aims to bring together leading experts in subfields of cardiovascular biomedicine to focus on topics of importance to the field. The theme of the 2022 Symposium was 'Cell Diversity in the Cardiovascular System, cell-autonomous and cell-cell signalling'. Experts in the field contributed their experimental and mathematical modelling perspectives and discussed emerging questions, controversies, and challenges in examining cell and signal diversity, co-ordination and interrelationships involved in cardiovascular function. This paper originates from the topics of formal presentations and informal discussions from the Symposium, which aimed to develop a holistic view of how the multiple cell types in the cardiovascular system integrate to influence cardiovascular function, disease progression and therapeutic strategies. The first section describes the major cell types (e.g. cardiomyocytes, vascular smooth muscle and endothelial cells, fibroblasts, neurons, immune cells, etc.) and the signals involved in cardiovascular function. The second section emphasizes the complexity at the subcellular, cellular and system levels in the context of cardiovascular development, ageing and disease. Finally, the third section surveys the technological innovations that allow the interrogation of this diversity and advancing our understanding of the integrated cardiovascular function and dysfunction.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Manuel F. Navedo
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Jeffrey J. Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- Department of Internal Medicine, University of California Davis, Davis, CA, USA
| | - Rose E. Dixon
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Montréal, Canada
- Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Ana M. Gomez
- Signaling and Cardiovascular Pathophysiology-UMR-S 1180, INSERM, Université Paris-Saclay, Orsay, France
| | - Osama F. Harraz
- Department of Pharmacology, Larner College of Medicine, and Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA
| | - Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - David K. Jones
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Trine Krogh-Madsen
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, New York, USA
| | - Walter Lee Murfee
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Matthew A. Nystoriak
- Department of Medicine, Division of Environmental Medicine, Center for Cardiometabolic Science, University of Louisville, Louisville, KY, 40202, USA
| | - Nikki G. Posnack
- Department of Pediatrics, Department of Pharmacology and Physiology, The George Washington University, Washington, DC, USA
- Sheikh Zayed Institute for Pediatric and Surgical Innovation, Children’s National Heart Institute, Children’s National Hospital, Washington, DC, USA
| | | | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
- Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University – Wexner Medical Center, Columbus, OH, USA
| | - Seth Weinberg
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
- Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University – Wexner Medical Center, Columbus, OH, USA
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Grandi E. Cell diversity and signalling in the cardiovascular system. J Physiol 2023; 601:2537-2539. [PMID: 37211722 PMCID: PMC10364990 DOI: 10.1113/jp284979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 05/19/2023] [Indexed: 05/23/2023] Open
Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
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12
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Heijman J, Zhou X, Morotti S, Molina CE, Abu-Taha IH, Tekook M, Jespersen T, Zhang Y, Dobrev S, Milting H, Gummert J, Karck M, Kamler M, El-Armouche A, Saljic A, Grandi E, Nattel S, Dobrev D. Enhanced Ca 2+-Dependent SK-Channel Gating and Membrane Trafficking in Human Atrial Fibrillation. Circ Res 2023; 132:e116-e133. [PMID: 36927079 PMCID: PMC10147588 DOI: 10.1161/circresaha.122.321858] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
BACKGROUND Small-conductance Ca2+-activated K+ (SK)-channel inhibitors have antiarrhythmic effects in animal models of atrial fibrillation (AF), presenting a potential novel antiarrhythmic option. However, the regulation of SK-channels in human atrial cardiomyocytes and its modification in patients with AF are poorly understood and were the object of this study. METHODS AND RESULTS Apamin-sensitive SK-channel current (ISK) and action potentials were recorded in human right-atrial cardiomyocytes from sinus rhythm control (Ctl) patients or patients with (long-term persistent) chronic AF (cAF). ISK was significantly higher, and apamin caused larger action potential prolongation in cAF- versus Ctl- cardiomyocytes. Sensitivity analyses in an in silico human atrial cardiomyocyte model identified IK1 and ISK as major regulators of repolarization. Increased ISK in cAF was not associated with increases in mRNA/protein levels of SK-channel subunits in either right- or left-atrial tissue homogenates or right-atrial cardiomyocytes, but the abundance of SK2 at the sarcolemma was larger in cAF versus Ctl in both tissue-slices and cardiomyocytes. Latrunculin-A and primaquine (anterograde and retrograde protein-trafficking inhibitors) eliminated the differences in SK2 membrane levels and ISK between Ctl- and cAF-cardiomyocytes. In addition, the phosphatase-inhibitor okadaic acid reduced ISK amplitude and abolished the difference between Ctl- and cAF-cardiomyocytes, indicating that reduced calmodulin-Thr80 phosphorylation due to increased protein phosphatase-2A levels in the SK-channel complex likely contribute to the greater ISK in cAF-cardiomyocytes. Finally, rapid electrical activation (5 Hz, 10 minutes) of Ctl-cardiomyocytes promoted SK2 membrane-localization, increased ISK and reduced action potential duration, effects greatly attenuated by apamin. Latrunculin-A or primaquine prevented the 5-Hz-induced ISK-upregulation. CONCLUSIONS ISK is upregulated in patients with cAF due to enhanced channel function, mediated by phosphatase-2A-dependent calmodulin-Thr80 dephosphorylation and tachycardia-dependent enhanced trafficking and targeting of SK-channel subunits to the sarcolemma. The observed AF-associated increases in ISK, which promote reentry-stabilizing action potential duration shortening, suggest an important role for SK-channels in AF auto-promotion and provide a rationale for pursuing the antiarrhythmic effects of SK-channel inhibition in humans.
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Affiliation(s)
- Jordi Heijman
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany (J.H., I.H.A.-T., M.T., Y.Z., S.D., A.S., S.N., D.D.)
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, the Netherlands (J.H.)
| | - Xiaobo Zhou
- First Department of Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany (X.Z.)
- DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Germany (X.Z.)
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Collaborative Innovation Center for Prevention of Cardiovascular Diseases, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China (X.Z.)
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis (S.M., E.G.)
| | - Cristina E Molina
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf and DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany (C.E.M.)
| | - Issam H Abu-Taha
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany (J.H., I.H.A.-T., M.T., Y.Z., S.D., A.S., S.N., D.D.)
| | - Marcel Tekook
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany (J.H., I.H.A.-T., M.T., Y.Z., S.D., A.S., S.N., D.D.)
| | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (T.J., A.S.)
| | - Yiqiao Zhang
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany (J.H., I.H.A.-T., M.T., Y.Z., S.D., A.S., S.N., D.D.)
| | - Shokoufeh Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany (J.H., I.H.A.-T., M.T., Y.Z., S.D., A.S., S.N., D.D.)
| | - Hendrik Milting
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Bad Oeynhausen, Germany (H.M., J.G.)
| | - Jan Gummert
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Bad Oeynhausen, Germany (H.M., J.G.)
| | - Matthias Karck
- Department of Cardiac Surgery, Heidelberg University Hospital, Germany (M. Karck)
| | - Markus Kamler
- Department of Thoracic and Cardiovascular Surgery, West German Heart and Vascular Center Essen, University Hospital Essen, Germany (M. Kamler)
| | - Ali El-Armouche
- Institute of Pharmacology, Dresden University of Technology, Germany (A.E.-A.)
| | - Arnela Saljic
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany (J.H., I.H.A.-T., M.T., Y.Z., S.D., A.S., S.N., D.D.)
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (T.J., A.S.)
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis (S.M., E.G.)
| | - Stanley Nattel
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany (J.H., I.H.A.-T., M.T., Y.Z., S.D., A.S., S.N., D.D.)
- Department of Medicine, Montreal Heart Institute and Université de Montréal (S.N., D.D.)
- Department of Pharmacology and Therapeutics, McGill University Montreal, Canada (S.N.)
- IHU LIRYC and Fondation Bordeaux Université, France (S.N.)
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany (J.H., I.H.A.-T., M.T., Y.Z., S.D., A.S., S.N., D.D.)
- Department of Medicine, Montreal Heart Institute and Université de Montréal (S.N., D.D.)
- Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX (D.D.)
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13
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Grandi E, Crotti M, Sigmund MC, Xu G, Tepper PG, Poelarends GJ. Biocatalytic Cascade Synthesis of Enantioenriched Epoxides and Triols from Biomass-Derived Synthons Driven by Specifically Designed Enzymes. Chemistry 2023:e202300697. [PMID: 36893219 DOI: 10.1002/chem.202300697] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/09/2023] [Accepted: 03/09/2023] [Indexed: 03/11/2023]
Abstract
Multi-enzymatic cascades exploiting engineered enzymes are a powerful tool for the tailor-made synthesis of complex molecules from simple inexpensive building blocks. In this work, we engineered the promiscuous enzyme 4-oxalocrotonate tautomerase (4-OT) into an effective aldolase with 160-fold increased activity compared to 4OT wild type. Subsequently, we applied the evolved 4-OT variant to perform an aldol condensation, followed by an epoxidation reaction catalyzed by a previously engineered 4-OT mutant, in a one-pot two-step cascade for the synthesis of enantioenriched epoxides (up to 98% ee) from biomass-derived starting materials. For three chosen substrates, the reaction was performed at milligram scale with product yields up to 68% and remarkably high enantioselectivity. Furthermore, we developed a three-step enzymatic cascade involving an epoxide hydrolase for the production of chiral aromatic 1,2,3-prim,sec,sec-triols with high enantiopurity and good isolated yields. The reported one-pot, three-step cascade, with no intermediate isolation and being completely cofactor-less, provides an attractive route for the synthesis of chiral aromatic triols from biomass-based synthons.
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Affiliation(s)
- Eleonora Grandi
- University of Groningen: Rijksuniversiteit Groningen, Chemical and Pharmaceutical Biology, NETHERLANDS
| | - Michele Crotti
- University of Groningen: Rijksuniversiteit Groningen, Chemical and Pharmaceutical Biology, NETHERLANDS
| | - Marie-Cathérine Sigmund
- University of Groningen: Rijksuniversiteit Groningen, Chemical and Pharmaceutical Biology, NETHERLANDS
| | - Guangcai Xu
- University of Groningen: Rijksuniversiteit Groningen, Chemical and Pharmaceutical Biology, NETHERLANDS
| | - Pieter G Tepper
- University of Groningen: Rijksuniversiteit Groningen, Chemical and Pharmaceutical Biology, NETHERLANDS
| | - Gerrit J Poelarends
- University of Groningen, Chemical and Pharmaceutical Biology, Antonius Deusinglaan 1, 9713 AV, Groningen, NETHERLANDS
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14
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Zhang X, Wu Y, Smith C, Morotti S, Grandi E, Ni H. Modeling sex differences in human atrial myocyte structural and Ca 2+ handling properties: Impact on Ca 2+-driven arrhythmia. Biophys J 2023; 122:380a. [PMID: 36783932 DOI: 10.1016/j.bpj.2022.11.2085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Xianwei Zhang
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Yixuan Wu
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Charlotte Smith
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Haibo Ni
- Department of Pharmacology, University of California Davis, Davis, CA, USA
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15
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Smith CER, Guevara AM, Wang L, Grandi E, Ripplinger CM. Sex differences in electrophysiology of the intact atria. Biophys J 2023; 122:380a. [PMID: 36783934 DOI: 10.1016/j.bpj.2022.11.2087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
| | - Amanda M Guevara
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Lianguo Wang
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
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16
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Peters CH, Rickert C, Morotti S, Grandi E, Aronow KA, Beam KG, Proenza C. The funny current If is essential for the fight-or-flight response in cardiac pacemaker cells. J Gen Physiol 2022; 154:213619. [PMID: 36305844 PMCID: PMC9812006 DOI: 10.1085/jgp.202213193] [Citation(s) in RCA: 2] [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: 05/12/2022] [Revised: 08/22/2022] [Accepted: 10/04/2022] [Indexed: 01/07/2023] Open
Abstract
The sympathetic nervous system fight-or-flight response is characterized by a rapid increase in heart rate, which is mediated by an increase in the spontaneous action potential (AP) firing rate of pacemaker cells in the sinoatrial node. Sympathetic neurons stimulate sinoatrial myocytes (SAMs) by activating β adrenergic receptors (βARs) and increasing cAMP. The funny current (If) is among the cAMP-sensitive currents in SAMs. If is critical for pacemaker activity, however, its role in the fight-or-flight response remains controversial. In this study, we used AP waveform analysis, machine learning, and dynamic clamp experiments in acutely isolated SAMs from mice to quantitatively define the AP waveform changes and role of If in the fight-or-flight increase in AP firing rate. We found that while βAR stimulation significantly altered nearly all AP waveform parameters, the increase in firing rate was only correlated with changes in a subset of parameters (diastolic duration, late AP duration, and diastolic depolarization rate). Dynamic clamp injection of the βAR-sensitive component of If showed that it accounts for ∼41% of the fight-or-flight increase in AP firing rate and 60% of the decrease in the interval between APs. Thus, If is an essential contributor to the fight-or-flight increase in heart rate.
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Affiliation(s)
- Colin H. Peters
- Department of Physiology & Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Christian Rickert
- Department of Physiology & Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, School of Medicine, Davis, CA
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, School of Medicine, Davis, CA
| | | | - Kurt G. Beam
- Department of Physiology & Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Catherine Proenza
- Department of Physiology & Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO,Division of Cardiology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO,Correspondence to Catherine Proenza:
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17
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Sigmund M, Xu G, Grandi E, Poelarends GJ. Enhancing the Peroxygenase Activity of a Cofactor-Independent Peroxyzyme by Directed Evolution Enabling Gram-Scale Epoxide Synthesis. Chemistry 2022; 28:e202201651. [PMID: 35861144 PMCID: PMC9804992 DOI: 10.1002/chem.202201651] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Indexed: 01/09/2023]
Abstract
Peroxygenases selectively incorporate oxygen into organic molecules making use of the environmentally friendly oxidant H2 O2 with water being the sole by-product. These biocatalysts can provide 'green' routes for the synthesis of enantioenriched epoxides, which are fundamental intermediates in the production of pharmaceuticals. The peroxyzyme 4-oxalocrotonate tautomerase (4-OT), catalysing the epoxidation of a variety of α,β-unsaturated aldehydes with H2 O2 , is outstanding because of its independence from any cost-intensive cofactor. However, its low-level peroxygenase activity and the decrease in the enantiomeric excess of the corresponding α,β-epoxy-aldehydes under preparative-scale conditions is limiting the potential of 4-OT. Herein we report the directed evolution of a tandem-fused 4-OT variant, which showed an ∼150-fold enhanced peroxygenase activity compared to 4-OT wild type, enabling the synthesis of α,β-epoxy-aldehydes in milligram- and gram-scale with high enantiopurity (up to 98 % ee) and excellent conversions. This engineered cofactor-independent peroxyzyme can provide new opportunities for the eco-friendly and practical synthesis of enantioenriched epoxides at large scale.
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Affiliation(s)
- Marie‐Cathérine Sigmund
- Department of Chemical and Pharmaceutical BiologyUniversity of GroningenAntonius Deusignlaan 19713 AVGroningenThe Netherlands
| | - Guangcai Xu
- Department of Chemical and Pharmaceutical BiologyUniversity of GroningenAntonius Deusignlaan 19713 AVGroningenThe Netherlands
| | - Eleonora Grandi
- Department of Chemical and Pharmaceutical BiologyUniversity of GroningenAntonius Deusignlaan 19713 AVGroningenThe Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical BiologyUniversity of GroningenAntonius Deusignlaan 19713 AVGroningenThe Netherlands
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18
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Zhang X, Smith CER, Morotti S, Edwards AG, Sato D, Louch WE, Ni H, Grandi E. Mechanisms of spontaneous Ca 2+ release-mediated arrhythmia in a novel 3D human atrial myocyte model: II Ca 2+ -handling protein variation. J Physiol 2022:10.1113/JP283602. [PMID: 36114707 PMCID: PMC10017376 DOI: 10.1113/jp283602] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/02/2022] [Indexed: 11/08/2022] Open
Abstract
Disruption of the transverse-axial tubule system (TATS) in diseases such as heart failure and atrial fibrillation occurs in combination with changes in the expression and distribution of key Ca2+ -handling proteins. Together this ultrastructural and ionic remodelling is associated with aberrant Ca2+ cycling and electrophysiological instabilities that underlie arrhythmic activity. However, due to the concurrent changes in TATs and Ca2+ -handling protein expression and localization that occur in disease it is difficult to distinguish their individual contributions to the arrhythmogenic state. To investigate this, we applied our novel 3D human atrial myocyte model with spatially detailed Ca2+ diffusion and TATS to investigate the isolated and interactive effects of changes in expression and localization of key Ca2+ -handling proteins and variable TATS density on Ca2+ -handling abnormality driven membrane instabilities. We show that modulating the expression and distribution of the sodium-calcium exchanger, ryanodine receptors and the sarcoplasmic reticulum (SR) Ca2+ buffer calsequestrin have varying pro- and anti-arrhythmic effects depending on the balance of opposing influences on SR Ca2+ leak-load and Ca2+ -voltage relationships. Interestingly, the impact of protein remodelling on Ca2+ -driven proarrhythmic behaviour varied dramatically depending on TATS density, with intermediately tubulated cells being more severely affected compared to detubulated and densely tubulated myocytes. This work provides novel mechanistic insight into the distinct and interactive consequences of TATS and Ca2+ -handling protein remodelling that underlies dysfunctional Ca2+ cycling and electrophysiological instability in disease. KEY POINTS: In our companion paper we developed a 3D human atrial myocyte model, coupling electrophysiology and Ca2+ handling with subcellular spatial details governed by the transverse-axial tubule system (TATS). Here we utilize this model to mechanistically examine the impact of TATS loss and changes in the expression and distribution of key Ca2+ -handling proteins known to be remodelled in disease on Ca2+ homeostasis and electrophysiological stability. We demonstrate that varying the expression and localization of these proteins has variable pro- and anti-arrhythmic effects with outcomes displaying dependence on TATS density. Whereas detubulated myocytes typically appear unaffected and densely tubulated cells seem protected, the arrhythmogenic effects of Ca2+ handling protein remodelling are profound in intermediately tubulated cells. Our work shows the interaction between TATS and Ca2+ -handling protein remodelling that underlies the Ca2+ -driven proarrhythmic behaviour observed in atrial fibrillation and may help to predict the effects of antiarrhythmic strategies at varying stages of ultrastructural remodelling.
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Affiliation(s)
- Xianwei Zhang
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | | | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | | | - Daisuke Sato
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Haibo Ni
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
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19
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Zhang X, Ni H, Morotti S, Smith CER, Sato D, Louch WE, Edwards AG, Grandi E. Mechanisms of spontaneous Ca 2+ release-mediated arrhythmia in a novel 3D human atrial myocyte model: I. Transverse-axial tubule variation. J Physiol 2022. [PMID: 36094888 PMCID: PMC10008525 DOI: 10.1113/jp283363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/02/2022] [Indexed: 11/08/2022] Open
Abstract
Intracellular calcium (Ca2+ ) cycling is tightly regulated in the healthy heart ensuring effective contraction. This is achieved by transverse (t)-tubule membrane invaginations that facilitate close coupling of key Ca2+ -handling proteins such as the L-type Ca2+ channel and Na+ -Ca2+ exchanger (NCX) on the cell surface with ryanodine receptors (RyRs) on the intracellular Ca2+ store. Although less abundant and regular than in the ventricle, t-tubules also exist in atrial myocytes as a network of transverse invaginations with axial extensions known as the transverse-axial tubule system (TATS). In heart failure and atrial fibrillation, there is TATS remodelling that is associated with aberrant Ca2+ -handling and Ca2+ -induced arrhythmic activity; however, the mechanism underlying this is not fully understood. To address this, we developed a novel 3D human atrial myocyte model that couples electrophysiology and Ca2+ -handling with variable TATS organization and density. We extensively parameterized and validated our model against experimental data to build a robust tool examining TATS regulation of subcellular Ca2+ release. We found that varying TATS density and thus the localization of key Ca2+ -handling proteins has profound effects on Ca2+ handling. Following TATS loss, there is reduced NCX that results in increased cleft Ca2+ concentration through decreased Ca2+ extrusion. This elevated Ca2+ increases RyR open probability causing spontaneous Ca2+ releases and the promotion of arrhythmogenic waves (especially in the cell interior) leading to voltage instabilities through delayed afterdepolarizations. In summary, the present study demonstrates a mechanistic link between TATS remodelling and Ca2+ -driven proarrhythmic behaviour that probably reflects the arrhythmogenic state observed in disease. KEY POINTS: Transverse-axial tubule systems (TATS) modulate Ca2+ handling and excitation-contraction coupling in atrial myocytes, with TATS remodelling in heart failure and atrial fibrillation being associated with altered Ca2+ cycling and subsequent arrhythmogenesis. To investigate the poorly understood mechanisms linking TATS variation and spontaneous Ca2+ release, we built, parameterized and validated a 3D human atrial myocyte model coupling electrophysiology and spatially-detailed subcellular Ca2+ handling governed by the TATS. Simulated TATS loss causes diastolic Ca2+ and voltage instabilities through reduced Na+ -Ca2+ exchanger-mediated Ca2+ removal, cleft Ca2+ accumulation and increased ryanodine receptor open probability, resulting in spontaneous Ca2+ release and promotion of arrhythmogenic waves and delayed afterdepolarizations. At fast electrical rates typical of atrial tachycardia/fibrillation, spontaneous Ca2+ releases are larger and more frequent in the cell interior than at the periphery. Our work provides mechanistic insight into how atrial TATS remodelling can lead to Ca2+ -driven instabilities that may ultimately contribute to the arrhythmogenic state in disease.
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Affiliation(s)
- Xianwei Zhang
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Haibo Ni
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | | | - Daisuke Sato
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Andrew G Edwards
- Department of Pharmacology, University of California Davis, Davis, CA, USA.,Simula Research Laboratory, Lysaker, Norway
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
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20
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Saljic A, Grandi E, Dobrev D. TGF-β1-induced endothelial-mesenchymal transition: a potential contributor to fibrotic remodeling in atrial fibrillation? J Clin Invest 2022; 132:161070. [PMID: 35775488 PMCID: PMC9246376 DOI: 10.1172/jci161070] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide, with an unmet therapeutic need. Fibrotic remodeling, in which collagen-producing atrial fibroblasts play a crucial role, substantially contributes to arrhythmia promotion and progression. In this issue of the JCI, Lai, Tsai, and co-authors reveal that TGF-β1 promoted endothelial-mesenchymal transition during AF and put forward the notion that, in the adult heart, atrial fibroblasts can originate from different cellular sources. These important findings extend our understanding of the origin, biology, and function of fibroblasts and offer possibilities for therapeutic targeting of fibrosis in AF.
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Affiliation(s)
- Arnela Saljic
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany.,Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, USA.,Montréal Heart Institute and University de Montréal, Medicine and Research Center, Montréal, Quebec, Canada
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21
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Zhang X, Ni H, Morotti S, Smith C, Sato D, Louch WE, Edwards AG, Grandi E. Quantifying the interactive arrhythmogenic effects of cell ultrastructural remodeling and calcium-handling protein redistribution in a three-dimensional model of the human atrial myocyte. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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22
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Zhang X, Smith C, Morotti S, Grandi E, Ni H. Sex-dependent differences in Ca2+-related arrhythmia revealed by human atrial myocyte models. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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23
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Wiesner N, Ghayoumi B, Ni H, Hegyi B, Morotti S, Bers DM, Chen-Izu Y, Grandi E, Sato D. Initiation and maintenance of arrhythmogenic action potential waves near the infarct zone in heart failure. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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24
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Ding Y, Lang D, Yan J, Bu H, Li H, Jiao K, Yang J, Ni H, Morotti S, Le T, Clark KJ, Port J, Ekker SC, Cao H, Zhang Y, Wang J, Grandi E, Li Z, Shi Y, Li Y, Glukhov AV, Xu X. A phenotype-based forward genetic screen identifies Dnajb6 as a sick sinus syndrome gene. eLife 2022; 11:77327. [PMID: 36255053 PMCID: PMC9642998 DOI: 10.7554/elife.77327] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 10/17/2022] [Indexed: 11/13/2022] Open
Abstract
Previously we showed the generation of a protein trap library made with the gene-break transposon (GBT) in zebrafish (Danio rerio) that could be used to facilitate novel functional genome annotation towards understanding molecular underpinnings of human diseases (Ichino et al, 2020). Here, we report a significant application of this library for discovering essential genes for heart rhythm disorders such as sick sinus syndrome (SSS). SSS is a group of heart rhythm disorders caused by malfunction of the sinus node, the heart's primary pacemaker. Partially owing to its aging-associated phenotypic manifestation and low expressivity, molecular mechanisms of SSS remain difficult to decipher. From 609 GBT lines screened, we generated a collection of 35 zebrafish insertional cardiac (ZIC) mutants in which each mutant traps a gene with cardiac expression. We further employed electrocardiographic measurements to screen these 35 ZIC lines and identified three GBT mutants with SSS-like phenotypes. More detailed functional studies on one of the arrhythmogenic mutants, GBT411, in both zebrafish and mouse models unveiled Dnajb6 as a novel SSS causative gene with a unique expression pattern within the subpopulation of sinus node pacemaker cells that partially overlaps with the expression of hyperpolarization activated cyclic nucleotide gated channel 4 (HCN4), supporting heterogeneity of the cardiac pacemaker cells.
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Affiliation(s)
- Yonghe Ding
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,The Affiliated Hospital of Qingdao University & The Biomedical Sciences Institute of Qingdao University (Qingdao Branch of SJTU Bio-X Institutes), Qingdao UniversityQingdaoChina
| | - Di Lang
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States,Department of Medicine, University of California, San FranciscoSan FranciscoUnited States
| | - Jianhua Yan
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,Division of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiaotong University School Of MedicineShanghaiChina
| | - Haisong Bu
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,Department of Cardiothoracic Surgery, Xiangya Hospital, Central South UniversityChangshaChina
| | - Hongsong Li
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,Department of Cardiovascular Medicine, Jiading District Central Hospital Affiliated Shanghai University of Medicine & Health ScienceShanghaiChina
| | - Kunli Jiao
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,Division of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiaotong University School Of MedicineShanghaiChina
| | - Jingchun Yang
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States
| | - Haibo Ni
- Department of Pharmacology, University of California, DavisDavisUnited States
| | - Stefano Morotti
- Department of Pharmacology, University of California, DavisDavisUnited States
| | - Tai Le
- Department of Biomedical Engineering, University of California, IrvineIrvineUnited States
| | - Karl J Clark
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States
| | - Jenna Port
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
| | - Stephen C Ekker
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States
| | - Hung Cao
- Department of Biomedical Engineering, University of California, IrvineIrvineUnited States,Department of Electrical Engineering and Computer Science, University of California, IrvineIrvineUnited States
| | - Yuji Zhang
- Department of Epidemiology and Public Health, University of Maryland School of MedicineBaltimoreUnited States
| | - Jun Wang
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at HoustonHoustonUnited States
| | - Eleonora Grandi
- Department of Pharmacology, University of California, DavisDavisUnited States
| | - Zhiqiang Li
- The Affiliated Hospital of Qingdao University & The Biomedical Sciences Institute of Qingdao University (Qingdao Branch of SJTU Bio-X Institutes), Qingdao UniversityQingdaoChina
| | - Yongyong Shi
- The Affiliated Hospital of Qingdao University & The Biomedical Sciences Institute of Qingdao University (Qingdao Branch of SJTU Bio-X Institutes), Qingdao UniversityQingdaoChina
| | - Yigang Li
- Division of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiaotong University School Of MedicineShanghaiChina
| | - Alexey V Glukhov
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
| | - Xiaolei Xu
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States
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Morotti S, Liu C, Hegyi B, Ni H, Fogli Iseppe A, Wang L, Pritoni M, Ripplinger CM, Bers DM, Edwards AG, Grandi E. Quantitative cross-species translators of cardiac myocyte electrophysiology: Model training, experimental validation, and applications. Sci Adv 2021; 7:eabg0927. [PMID: 34788089 PMCID: PMC8598003 DOI: 10.1126/sciadv.abg0927] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 09/28/2021] [Indexed: 05/13/2023]
Abstract
Animal experimentation is key in the evaluation of cardiac efficacy and safety of novel therapeutic compounds. However, interspecies differences in the mechanisms regulating excitation-contraction coupling can limit the translation of experimental findings from animal models to human physiology and undermine the assessment of drugs’ efficacy and safety. Here, we built a suite of translators for quantitatively mapping electrophysiological responses in ventricular myocytes across species. We trained these statistical operators using a broad dataset obtained by simulating populations of our biophysically detailed computational models of action potential and Ca2+ transient in mouse, rabbit, and human. We then tested our translators against experimental data describing the response to stimuli, such as ion channel block, change in beating rate, and β-adrenergic challenge. We demonstrate that this approach is well suited to predicting the effects of perturbations across different species or experimental conditions and suggest its integration into mechanistic studies and drug development pipelines.
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Affiliation(s)
- Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Caroline Liu
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Haibo Ni
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Alex Fogli Iseppe
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Lianguo Wang
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Marco Pritoni
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Andrew G. Edwards
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
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26
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Iseppe AF, Ni H, Zhu S, Zhang X, Coppini R, Yang PC, Srivatsa U, Clancy CE, Edwards AG, Morotti S, Grandi E. Sex-Specific Classification of Drug-Induced Torsade de Pointes Susceptibility Using Cardiac Simulations and Machine Learning. Clin Pharmacol Ther 2021; 110:380-391. [PMID: 33772748 PMCID: PMC8316283 DOI: 10.1002/cpt.2240] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [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: 11/18/2020] [Accepted: 03/16/2021] [Indexed: 11/09/2022]
Abstract
Torsade de Pointes (TdP), a rare but lethal ventricular arrhythmia, is a toxic side effect of many drugs. To assess TdP risk, safety regulatory guidelines require quantification of hERG channel block in vitro and QT interval prolongation in vivo for all new therapeutic compounds. Unfortunately, these have proven to be poor predictors of torsadogenic risk, and are likely to have prevented safe compounds from reaching clinical phases. Although this has stimulated numerous efforts to define new paradigms for cardiac safety, none of the recently developed strategies accounts for patient conditions. In particular, despite being a well-established independent risk factor for TdP, female sex is vastly under-represented in both basic research and clinical studies, and thus current TdP metrics are likely biased toward the male sex. Here, we apply statistical learning to synthetic data, generated by simulating drug effects on cardiac myocyte models capturing male and female electrophysiology, to develop new sex-specific classification frameworks for TdP risk. We show that (i) TdP classifiers require different features in females vs. males; (ii) male-based classifiers perform more poorly when applied to female data; and (iii) female-based classifier performance is largely unaffected by acute effects of hormones (i.e., during various phases of the menstrual cycle). Notably, when predicting TdP risk of intermediate drugs on female simulated data, male-biased predictive models consistently underestimate TdP risk in women. Therefore, we conclude that pipelines for preclinical cardiotoxicity risk assessment should consider sex as a key variable to avoid potentially life-threatening consequences for the female population.
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Affiliation(s)
- Alex Fogli Iseppe
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Haibo Ni
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Sicheng Zhu
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Xianwei Zhang
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Raffaele Coppini
- Department of Neuroscience, Psychology, Drug Sciences and Child Health (NeuroFarBa), University of Florence, Italy
| | - Pei-Chi Yang
- Department of Physiology and Membrane Biology, University of California, Davis, CA, USA
| | - Uma Srivatsa
- Department of Internal Medicine, University of California, Davis, CA, USA
| | - Colleen E. Clancy
- Department of Pharmacology, University of California, Davis, CA, USA
- Department of Physiology and Membrane Biology, University of California, Davis, CA, USA
| | - Andrew G. Edwards
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, CA, USA
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27
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Peters CH, Liu PW, Morotti S, Gantz SC, Grandi E, Bean BP, Proenza C. Bidirectional flow of the funny current (I f) during the pacemaking cycle in murine sinoatrial node myocytes. Proc Natl Acad Sci U S A 2021; 118:e2104668118. [PMID: 34260402 PMCID: PMC8285948 DOI: 10.1073/pnas.2104668118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [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] [Indexed: 02/07/2023] Open
Abstract
Sinoatrial node myocytes (SAMs) act as cardiac pacemaker cells by firing spontaneous action potentials (APs) that initiate each heartbeat. The funny current (If) is critical for the generation of these spontaneous APs; however, its precise role during the pacemaking cycle remains unresolved. Here, we used the AP-clamp technique to quantify If during the cardiac cycle in mouse SAMs. We found that If is persistently active throughout the sinoatrial AP, with surprisingly little voltage-dependent gating. As a consequence, it carries both inward and outward current around its reversal potential of -30 mV. Despite operating at only 2 to 5% of its maximal conductance, If carries a substantial fraction of both depolarizing and repolarizing net charge movement during the firing cycle. We also show that β-adrenergic receptor stimulation increases the percentage of net depolarizing charge moved by If, consistent with a contribution of If to the fight-or-flight increase in heart rate. These properties were confirmed by heterologously expressed HCN4 channels and by mathematical models of If Modeling further suggested that the slow rates of activation and deactivation of the HCN4 isoform underlie the persistent activity of If during the sinoatrial AP. These results establish a new conceptual framework for the role of If in pacemaking, in which it operates at a very small fraction of maximal activation but nevertheless drives membrane potential oscillations in SAMs by providing substantial driving force in both inward and outward directions.
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Affiliation(s)
- Colin H Peters
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Pin W Liu
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Stephanie C Gantz
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Bruce P Bean
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045;
- Department of Medicine, Division of Cardiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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28
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McCulloch AD, Grandi E, Saucerman JJ. Computational models of cardiovascular regulatory mechanisms. J Mol Cell Cardiol 2021; 155:111. [PMID: 33647311 DOI: 10.1016/j.yjmcc.2021.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 01/19/2021] [Indexed: 11/19/2022]
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29
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Morotti S, Ni H, Peters CH, Rickert C, Asgari-Targhi A, Sato D, Glukhov AV, Proenza C, Grandi E. Intracellular Na + Modulates Pacemaking Activity in Murine Sinoatrial Node Myocytes: An In Silico Analysis. Int J Mol Sci 2021; 22:5645. [PMID: 34073281 PMCID: PMC8198068 DOI: 10.3390/ijms22115645] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/21/2021] [Accepted: 05/25/2021] [Indexed: 12/19/2022] Open
Abstract
Background: The mechanisms underlying dysfunction in the sinoatrial node (SAN), the heart's primary pacemaker, are incompletely understood. Electrical and Ca2+-handling remodeling have been implicated in SAN dysfunction associated with heart failure, aging, and diabetes. Cardiomyocyte [Na+]i is also elevated in these diseases, where it contributes to arrhythmogenesis. Here, we sought to investigate the largely unexplored role of Na+ homeostasis in SAN pacemaking and test whether [Na+]i dysregulation may contribute to SAN dysfunction. Methods: We developed a dataset-specific computational model of the murine SAN myocyte and simulated alterations in the major processes of Na+ entry (Na+/Ca2+ exchanger, NCX) and removal (Na+/K+ ATPase, NKA). Results: We found that changes in intracellular Na+ homeostatic processes dynamically regulate SAN electrophysiology. Mild reductions in NKA and NCX function increase myocyte firing rate, whereas a stronger reduction causes bursting activity and loss of automaticity. These pathologic phenotypes mimic those observed experimentally in NCX- and ankyrin-B-deficient mice due to altered feedback between the Ca2+ and membrane potential clocks underlying SAN firing. Conclusions: Our study generates new testable predictions and insight linking Na+ homeostasis to Ca2+ handling and membrane potential dynamics in SAN myocytes that may advance our understanding of SAN (dys)function.
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Affiliation(s)
- Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA; (H.N.); (A.A.-T.); (D.S.)
| | - Haibo Ni
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA; (H.N.); (A.A.-T.); (D.S.)
| | - Colin H. Peters
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; (C.H.P.); (C.R.); (C.P.)
| | - Christian Rickert
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; (C.H.P.); (C.R.); (C.P.)
| | - Ameneh Asgari-Targhi
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA; (H.N.); (A.A.-T.); (D.S.)
| | - Daisuke Sato
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA; (H.N.); (A.A.-T.); (D.S.)
| | - Alexey V. Glukhov
- Department of Medicine, Cardiovascular Medicine, University of Wisconsin Madison School of Medicine and Public Health, Madison, WI 53705, USA;
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; (C.H.P.); (C.R.); (C.P.)
- Department of Medicine, Division of Cardiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA; (H.N.); (A.A.-T.); (D.S.)
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30
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Zhang X, Ni H, Morotti S, Sato D, Louch WE, Edwards AG, Grandi E. Quantifying the Arrhythmogenic Effects of Subcellular Structural Variations in a Three-Dimensional Model of the Human Atrial Myocyte. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.2097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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31
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Ni H, Zhang X, Morotti S, Grandi E. Pka and CaMKII Signaling Synergistically Promotes Atrial Arrhythmia in Populations of Human Atrial Tissues. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.2096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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32
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Fogli Iseppe A, Morotti S, Tekook M, Hoffmann D, Edwards AG, Dobrev D, Grandi E. A Modeling Framework for Investigating the Role of Human Atrial Fibroblast Calcium Signaling in Fibrogenesis. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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33
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Zaza A, Grandi E. Mechanisms of Cav3-associated arrhythmia: Protein or microdomain dysfunction? Int J Cardiol 2020; 320:97-99. [DOI: 10.1016/j.ijcard.2020.06.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 06/24/2020] [Indexed: 10/23/2022]
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Ni H, Fogli Iseppe A, Giles WR, Narayan SM, Zhang H, Edwards AG, Morotti S, Grandi E. Populations of in silico myocytes and tissues reveal synergy of multiatrial-predominant K + -current block in atrial fibrillation. Br J Pharmacol 2020; 177:4497-4515. [PMID: 32667679 DOI: 10.1111/bph.15198] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 06/22/2020] [Accepted: 07/03/2020] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE Pharmacotherapy of atrial fibrillation (AF), the most common cardiac arrhythmia, remains unsatisfactory due to low efficacy and safety concerns. New therapeutic strategies target atrial-predominant ion-channels and involve multichannel block (poly)therapy. As AF is characterized by rapid and irregular atrial activations, compounds displaying potent antiarrhythmic effects at fast and minimal effects at slow rates are desirable. We present a novel systems pharmacology framework to quantitatively evaluate synergistic anti-AF effects of combined block of multiple atrial-predominant K+ currents (ultra-rapid delayed rectifier K+ current, IKur , small conductance Ca2+ -activated K+ current, IKCa , K2P 3.1 2-pore-domain K+ current, IK2P ) in AF. EXPERIMENTAL APPROACH We constructed experimentally calibrated populations of virtual atrial myocyte models in normal sinus rhythm and AF-remodelled conditions using two distinct, well-established atrial models. Sensitivity analyses on our atrial populations was used to investigate the rate dependence of action potential duration (APD) changes due to blocking IKur , IK2P or IKCa and interactions caused by blocking of these currents in modulating APD. Block was simulated in both single myocytes and one-dimensional tissue strands to confirm insights from the sensitivity analyses and examine anti-arrhythmic effects of multi-atrial-predominant K+ current block in single cells and coupled tissue. KEY RESULTS In both virtual atrial myocytes and tissues, multiple atrial-predominant K+ -current block promoted favourable positive rate-dependent APD prolongation and displayed positive rate-dependent synergy, that is, increasing synergistic antiarrhythmic effects at fast pacing versus slow rates. CONCLUSION AND IMPLICATIONS Simultaneous block of multiple atrial-predominant K+ currents may be a valuable antiarrhythmic pharmacotherapeutic strategy for AF.
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Affiliation(s)
- Haibo Ni
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Alex Fogli Iseppe
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Wayne R Giles
- Faculties of Kinesiology and Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Sanjiv M Narayan
- Division of Cardiology, Cardiovascular Institute, Stanford University, Stanford, CA, USA
| | - Henggui Zhang
- Biological Physics Group, School of Physics and Astronomy, The University of Manchester, Manchester, UK
| | - Andrew G Edwards
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, CA, USA
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35
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Xu B, Li M, Wang Y, Zhao M, Morotti S, Shi Q, Wang Q, Barbagallo F, Teoh JP, Reddy GR, Bayne EF, Liu Y, Shen A, Puglisi JL, Ge Y, Li J, Grandi E, Nieves-Cintron M, Xiang YK. GRK5 Controls SAP97-Dependent Cardiotoxic β 1 Adrenergic Receptor-CaMKII Signaling in Heart Failure. Circ Res 2020; 127:796-810. [PMID: 32507058 DOI: 10.1161/circresaha.119.316319] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
RATIONALE Cardiotoxic β1 adrenergic receptor (β1AR)-CaMKII (calmodulin-dependent kinase II) signaling is a major and critical feature associated with development of heart failure. SAP97 (synapse-associated protein 97) is a multifunctional scaffold protein that binds directly to the C-terminus of β1AR and organizes a receptor signalosome. OBJECTIVE We aim to elucidate the dynamics of β1AR-SAP97 signalosome and its potential role in chronic cardiotoxic β1AR-CaMKII signaling that contributes to development of heart failure. METHODS AND RESULTS The integrity of cardiac β1AR-SAP97 complex was examined in heart failure. Cardiac-specific deletion of SAP97 was developed to examine β1AR signaling in aging mice, after chronic adrenergic stimulation, and in pressure overload hypertrophic heart failure. We show that the β1AR-SAP97 signaling complex is reduced in heart failure. Cardiac-specific deletion of SAP97 yields an aging-dependent cardiomyopathy and exacerbates cardiac dysfunction induced by chronic adrenergic stimulation and pressure overload, which are associated with elevated CaMKII activity. Loss of SAP97 promotes PKA (protein kinase A)-dependent association of β1AR with arrestin2 and CaMKII and turns on an Epac (exchange protein directly activated by cAMP)-dependent activation of CaMKII, which drives detrimental functional and structural remodeling in myocardium. Moreover, we have identified that GRK5 (G-protein receptor kinase-5) is necessary to promote agonist-induced dissociation of SAP97 from β1AR. Cardiac deletion of GRK5 prevents adrenergic-induced dissociation of β1AR-SAP97 complex and increases in CaMKII activity in hearts. CONCLUSIONS These data reveal a critical role of SAP97 in maintaining the integrity of cardiac β1AR signaling and a detrimental cardiac GRK5-CaMKII axis that can be potentially targeted in heart failure therapy. Graphical Abstract: A graphical abstract is available for this article.
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Affiliation(s)
- Bing Xu
- From the VA Northern California Health Care System, Mather, CA (B.X., Y.K.X.).,Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Minghui Li
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.).,Nanjing First Hospital, Nanjing Medical University, China (M.L.)
| | - Ying Wang
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Meimi Zhao
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Stefano Morotti
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Qian Shi
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Qingtong Wang
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.).,Institute of Clinical Pharmacology, Anhui Medical University, Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Hefei, China (Q.W.)
| | - Federica Barbagallo
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Jian-Peng Teoh
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Gopireddy R Reddy
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Elizabeth F Bayne
- Department of Chemistry, University of Wisconsin-Madison (E.F.B., Y.G.)
| | - Yongming Liu
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.).,Shuguang Hospital, Shanghai University of Traditional Medicine, China (Y.L.)
| | - Ao Shen
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.).,School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou Medical University, China (A.S.)
| | - Jose L Puglisi
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison (E.F.B., Y.G.)
| | - Ji Li
- Department of Surgery, University of South Florida, Tampa (J.L.)
| | - Eleonora Grandi
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Madeline Nieves-Cintron
- Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
| | - Yang K Xiang
- From the VA Northern California Health Care System, Mather, CA (B.X., Y.K.X.).,Department of Pharmacology, University of California at Davis (B.X., M.L., Y.W., M.Z., S.M., Q.S., Q.W., F.B., J.-P.T., G.R.R., Y.L., A.S., J.L.P., E.G., M.N.-C., Y.K.X.)
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Grandi E, Dobrev D. Atrial fibrillation in a dish: insights into atrial arrhythmogenesis from induced pluripotent stem cell-derived cardiomyocytes. Cardiovasc Res 2020; 116:1089-1091. [PMID: 31860074 DOI: 10.1093/cvr/cvz342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Tupper Hall rm 2427, Davis, CA 95616, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstr. 55, D-45122 Essen, Germany
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Grandi E, Ni H, Iseppe AF, Ghayoumi B, Wang L, Jiang Y, Chen YJ, Bers DM, Sato D, Edwards AG, Ripplinger CM, Morotti S. SPARC: Found in translation: quantitative predictors of cardiac myocyte responses to β‐adrenergic stimulation across species. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.06511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Tazmini K, Frisk M, Lewalle A, Laasmaa M, Morotti S, Lipsett DB, Manfra O, Skogestad J, Aronsen JM, Sejersted OM, Sjaastad I, Edwards AG, Grandi E, Niederer SA, Øie E, Louch WE. Hypokalemia Promotes Arrhythmia by Distinct Mechanisms in Atrial and Ventricular Myocytes. Circ Res 2020; 126:889-906. [PMID: 32070187 PMCID: PMC7098435 DOI: 10.1161/circresaha.119.315641] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE Hypokalemia occurs in up to 20% of hospitalized patients and is associated with increased incidence of ventricular and atrial fibrillation. It is unclear whether these differing types of arrhythmia result from direct and perhaps distinct effects of hypokalemia on cardiomyocytes. OBJECTIVE To investigate proarrhythmic mechanisms of hypokalemia in ventricular and atrial myocytes. METHODS AND RESULTS Experiments were performed in isolated rat myocytes exposed to simulated hypokalemia conditions (reduction of extracellular [K+] from 5.0 to 2.7 mmol/L) and supported by mathematical modeling studies. Ventricular cells subjected to hypokalemia exhibited Ca2+ overload and increased generation of both spontaneous Ca2+ waves and delayed afterdepolarizations. However, similar Ca2+-dependent spontaneous activity during hypokalemia was only observed in a minority of atrial cells that were observed to contain t-tubules. This effect was attributed to close functional pairing of the Na+-K+ ATPase and Na+-Ca2+ exchanger proteins within these structures, as reduction in Na+ pump activity locally inhibited Ca2+ extrusion. Ventricular myocytes and tubulated atrial myocytes additionally exhibited early afterdepolarizations during hypokalemia, associated with Ca2+ overload. However, early afterdepolarizations also occurred in untubulated atrial cells, despite Ca2+ quiescence. These phase-3 early afterdepolarizations were rather linked to reactivation of nonequilibrium Na+ current, as they were rapidly blocked by tetrodotoxin. Na+ current-driven early afterdepolarizations in untubulated atrial cells were enabled by membrane hyperpolarization during hypokalemia and short action potential configurations. Brief action potentials were in turn maintained by ultra-rapid K+ current (IKur); a current which was found to be absent in tubulated atrial myocytes and ventricular myocytes. CONCLUSIONS Distinct mechanisms underlie hypokalemia-induced arrhythmia in the ventricle and atrium but also vary between atrial myocytes depending on subcellular structure and electrophysiology.
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Affiliation(s)
- Kiarash Tazmini
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- Department of Internal Medicine, Diakonhjemmet Hospital, Oslo, Norway (K.T., E.Ø.)
| | - Michael Frisk
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
| | - Alexandre Lewalle
- Division of Imaging Sciences and Biomedical Engineering, King’s College London, United Kingdom (A.L., S.A.N.)
| | - Martin Laasmaa
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
| | - Stefano Morotti
- Department of Pharmacology, School of Medicine, University of California Davis (S.M., A.G.E., E.G.)
| | - David B. Lipsett
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
| | - Ornella Manfra
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
| | - Jonas Skogestad
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
| | - Jan M. Aronsen
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- Bjørknes College, Oslo, Norway (J.M.A.)
| | - Ole M. Sejersted
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
| | - Ivar Sjaastad
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
| | - Andrew G. Edwards
- Department of Pharmacology, School of Medicine, University of California Davis (S.M., A.G.E., E.G.)
| | - Eleonora Grandi
- Department of Pharmacology, School of Medicine, University of California Davis (S.M., A.G.E., E.G.)
| | - Steven A. Niederer
- Division of Imaging Sciences and Biomedical Engineering, King’s College London, United Kingdom (A.L., S.A.N.)
| | - Erik Øie
- Department of Internal Medicine, Diakonhjemmet Hospital, Oslo, Norway (K.T., E.Ø.)
| | - William E. Louch
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
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Dai W, Morotti S, Moskowitz I, Grandi E, Weber C. Targeting Ca2+ Fluxes in Atrial Fibrillation. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Morotti S, Ni H, Wang L, Fogli Iseppe A, Bers DM, Edwards AG, Ripplinger CM, Grandi E. Quantitative Cross-Species Prediction of β-Adrenergic Response in Ventricular Myocytes. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Zhang X, Ni H, Morotti S, Louch WE, Edwards AG, Sato D, Grandi E. Effects of Ultrastructural Remodeling on Calcium Signaling and Electrophysiology in a Three-Dimensional Model of the Human Atrial Myocyte. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Iseppe AF, Ni H, Zhang X, Srivatsa U, Edwards AG, Morotti S, Grandi E. A Machine Learning Approach for Investigating Sex Differences in Torsade De Pointes Susceptibility. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Tazmini K, Frisk M, Laasmaa M, Lewalle A, Morotti S, Lipsett DB, Manfra O, Skogested J, Magnus Aronsen J, Sjaastad I, Edwards AG, Grandi E, Niederer SA, Øie E, Louch WE. Hypokalemia Promotes Arrhythmia by Distinct Mechanisms in Atrial and Ventricular Myocytes. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Li Z, Mirams GR, Yoshinaga T, Ridder BJ, Han X, Chen JE, Stockbridge NL, Wisialowski TA, Damiano B, Severi S, Morissette P, Kowey PR, Holbrook M, Smith G, Rasmusson RL, Liu M, Song Z, Qu Z, Leishman DJ, Steidl‐Nichols J, Rodriguez B, Bueno‐Orovio A, Zhou X, Passini E, Edwards AG, Morotti S, Ni H, Grandi E, Clancy CE, Vandenberg J, Hill A, Nakamura M, Singer T, Polonchuk L, Greiter‐Wilke A, Wang K, Nave S, Fullerton A, Sobie EA, Paci M, Musuamba Tshinanu F, Strauss DG. General Principles for the Validation of Proarrhythmia Risk Prediction Models: An Extension of the CiPA In Silico Strategy. Clin Pharmacol Ther 2020; 107:102-111. [PMID: 31709525 PMCID: PMC6977398 DOI: 10.1002/cpt.1647] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 09/06/2019] [Indexed: 12/27/2022]
Abstract
This white paper presents principles for validating proarrhythmia risk prediction models for regulatory use as discussed at the In Silico Breakout Session of a Cardiac Safety Research Consortium/Health and Environmental Sciences Institute/US Food and Drug Administration-sponsored Think Tank Meeting on May 22, 2018. The meeting was convened to evaluate the progress in the development of a new cardiac safety paradigm, the Comprehensive in Vitro Proarrhythmia Assay (CiPA). The opinions regarding these principles reflect the collective views of those who participated in the discussion of this topic both at and after the breakout session. Although primarily discussed in the context of in silico models, these principles describe the interface between experimental input and model-based interpretation and are intended to be general enough to be applied to other types of nonclinical models for proarrhythmia assessment. This document was developed with the intention of providing a foundation for more consistency and harmonization in developing and validating different models for proarrhythmia risk prediction using the example of the CiPA paradigm.
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Zhang J, Grandi E, Fu H, Saravanan T, Bothof L, Tepper PG, Thunnissen AWH, Poelarends GJ. Engineered C–N Lyase: Enantioselective Synthesis of Chiral Synthons for Artificial Dipeptide Sweeteners. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201910704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Jielin Zhang
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Eleonora Grandi
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Haigen Fu
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Thangavelu Saravanan
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Laura Bothof
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Pieter G. Tepper
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Andy‐Mark W. H. Thunnissen
- Molecular Enzymology Group Groningen Institute of Biomolecular Sciences and Biotechnology University of Groningen Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
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Zhang J, Grandi E, Fu H, Saravanan T, Bothof L, Tepper PG, Thunnissen AMWH, Poelarends GJ. Engineered C-N Lyase: Enantioselective Synthesis of Chiral Synthons for Artificial Dipeptide Sweeteners. Angew Chem Int Ed Engl 2019; 59:429-435. [PMID: 31625664 PMCID: PMC6973171 DOI: 10.1002/anie.201910704] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [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: 08/21/2019] [Revised: 10/11/2019] [Indexed: 11/24/2022]
Abstract
Aspartic acid derivatives with branched N‐alkyl or N‐arylalkyl substituents are valuable precursors to artificial dipeptide sweeteners such as neotame and advantame. The development of a biocatalyst to synthesize these compounds in a single asymmetric step is an as yet unmet challenge. Reported here is an enantioselective biocatalytic synthesis of various difficult N‐substituted aspartic acids, including N‐(3,3‐dimethylbutyl)‐l‐aspartic acid and N‐[3‐(3‐hydroxy‐4‐methoxyphenyl)propyl]‐l‐aspartic acid, precursors to neotame and advantame, respectively, using an engineered variant of ethylenediamine‐N,N′‐disuccinic acid (EDDS) lyase from Chelativorans sp. BNC1. This engineered C–N lyase (mutant D290M/Y320M) displayed a remarkable 1140‐fold increase in activity for the selective hydroamination of fumarate compared to that of the wild‐type enzyme. These results present new opportunities to develop practical multienzymatic processes for the more sustainable and step‐economic synthesis of an important class of food additives.
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Affiliation(s)
- Jielin Zhang
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Eleonora Grandi
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Haigen Fu
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Thangavelu Saravanan
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Laura Bothof
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Pieter G Tepper
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Andy-Mark W H Thunnissen
- Molecular Enzymology Group, Groningen Institute of Biomolecular Sciences and Biotechnology, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
| | - Gerrit J Poelarends
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
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Kernik DC, Morotti S, Wu H, Garg P, Duff HJ, Kurokawa J, Jalife J, Wu JC, Grandi E, Clancy CE. A computational model of induced pluripotent stem-cell derived cardiomyocytes incorporating experimental variability from multiple data sources. J Physiol 2019; 597:4533-4564. [PMID: 31278749 PMCID: PMC6767694 DOI: 10.1113/jp277724] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [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: 01/18/2019] [Accepted: 07/05/2019] [Indexed: 12/22/2022] Open
Abstract
Key points Induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs) capture patient‐specific genotype–phenotype relationships, as well as cell‐to‐cell variability of cardiac electrical activity Computational modelling and simulation provide a high throughput approach to reconcile multiple datasets describing physiological variability, and also identify vulnerable parameter regimes We have developed a whole‐cell model of iPSC‐CMs, composed of single exponential voltage‐dependent gating variable rate constants, parameterized to fit experimental iPSC‐CM outputs We have utilized experimental data across multiple laboratories to model experimental variability and investigate subcellular phenotypic mechanisms in iPSC‐CMs This framework links molecular mechanisms to cellular‐level outputs by revealing unique subsets of model parameters linked to known iPSC‐CM phenotypes
Abstract There is a profound need to develop a strategy for predicting patient‐to‐patient vulnerability in the emergence of cardiac arrhythmia. A promising in vitro method to address patient‐specific proclivity to cardiac disease utilizes induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs). A major strength of this approach is that iPSC‐CMs contain donor genetic information and therefore capture patient‐specific genotype–phenotype relationships. A cited detriment of iPSC‐CMs is the cell‐to‐cell variability observed in electrical activity. We postulated, however, that cell‐to‐cell variability may constitute a strength when appropriately utilized in a computational framework to build cell populations that can be employed to identify phenotypic mechanisms and pinpoint key sensitive parameters. Thus, we have exploited variation in experimental data across multiple laboratories to develop a computational framework for investigating subcellular phenotypic mechanisms. We have developed a whole‐cell model of iPSC‐CMs composed of simple model components comprising ion channel models with single exponential voltage‐dependent gating variable rate constants, parameterized to fit experimental iPSC‐CM data for all major ionic currents. By optimizing ionic current model parameters to multiple experimental datasets, we incorporate experimentally‐observed variability in the ionic currents. The resulting population of cellular models predicts robust inter‐subject variability in iPSC‐CMs. This approach links molecular mechanisms to known cellular‐level iPSC‐CM phenotypes, as shown by comparing immature and mature subpopulations of models to analyse the contributing factors underlying each phenotype. In the future, the presented models can be readily expanded to include genetic mutations and pharmacological interventions for studying the mechanisms of rare events, such as arrhythmia triggers. Induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs) capture patient‐specific genotype–phenotype relationships, as well as cell‐to‐cell variability of cardiac electrical activity Computational modelling and simulation provide a high throughput approach to reconcile multiple datasets describing physiological variability, and also identify vulnerable parameter regimes We have developed a whole‐cell model of iPSC‐CMs, composed of single exponential voltage‐dependent gating variable rate constants, parameterized to fit experimental iPSC‐CM outputs We have utilized experimental data across multiple laboratories to model experimental variability and investigate subcellular phenotypic mechanisms in iPSC‐CMs This framework links molecular mechanisms to cellular‐level outputs by revealing unique subsets of model parameters linked to known iPSC‐CM phenotypes
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Affiliation(s)
- Divya C Kernik
- Department of Physiology and Membrane Biology, Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, USA
| | - Stefano Morotti
- Department of Pharmacology, School of Medicine, University of California, Davis, CA, USA
| | - HaoDi Wu
- Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Priyanka Garg
- Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Henry J Duff
- Libin Cardiovascular Institute of Alberta, Faculty of Medicine, University of Calgary, Calgary, AB, Canada
| | - Junko Kurokawa
- Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - José Jalife
- Department of Internal Medicine, Center for Arrhythmia Research, Cardiovascular Research Center, University of Michigan, Ann Arbor, MI, USA.,Centro Nacional de Investigaciones Cardiovasculares (CNIC), and CIBERV, Madrid, Spain
| | - Joseph C Wu
- Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Eleonora Grandi
- Department of Pharmacology, School of Medicine, University of California, Davis, CA, USA
| | - Colleen E Clancy
- Department of Physiology and Membrane Biology, Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, USA
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Wang L, Morotti S, Tapa S, Francis Stuart SD, Jiang Y, Wang Z, Myles RC, Brack KE, Ng GA, Bers DM, Grandi E, Ripplinger CM. Different paths, same destination: divergent action potential responses produce conserved cardiac fight-or-flight response in mouse and rabbit hearts. J Physiol 2019; 597:3867-3883. [PMID: 31215643 DOI: 10.1113/jp278016] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 06/17/2019] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS Cardiac electrophysiology and Ca2+ handling change rapidly during the fight-or-flight response to meet physiological demands. Despite dramatic differences in cardiac electrophysiology, the cardiac fight-or-flight response is highly conserved across species. In this study, we performed physiological sympathetic nerve stimulation (SNS) while optically mapping cardiac action potentials and intracellular Ca2+ transients in innervated mouse and rabbit hearts. Despite similar heart rate and Ca2+ handling responses between mouse and rabbit hearts, we found notable species differences in spatio-temporal repolarization dynamics during SNS. Species-specific computational models revealed that these electrophysiological differences allowed for enhanced Ca2+ handling (i.e. enhanced inotropy) in each species, suggesting that electrophysiological responses are fine-tuned across species to produce optimal cardiac fight-or-flight responses. ABSTRACT Sympathetic activation of the heart results in positive chronotropy and inotropy, which together rapidly increase cardiac output. The precise mechanisms that produce the electrophysiological and Ca2+ handling changes underlying chronotropic and inotropic responses have been studied in detail in isolated cardiac myocytes. However, few studies have examined the dynamic effects of physiological sympathetic nerve activation on cardiac action potentials (APs) and intracellular Ca2+ transients (CaTs) in the intact heart. Here, we performed bilateral sympathetic nerve stimulation (SNS) in fully innervated, Langendorff-perfused rabbit and mouse hearts. Dual optical mapping with voltage- and Ca2+ -sensitive dyes allowed for analysis of spatio-temporal AP and CaT dynamics. The rabbit heart responded to SNS with a monotonic increase in heart rate (HR), monotonic decreases in AP and CaT duration (APD, CaTD), and a monotonic increase in CaT amplitude. The mouse heart had similar HR and CaT responses; however, a pronounced biphasic APD response occurred, with initial prolongation (50.9 ± 5.1 ms at t = 0 s vs. 60.6 ± 4.1 ms at t = 15 s, P < 0.05) followed by shortening (46.5 ± 9.1 ms at t = 60 s, P = NS vs. t = 0). We determined the biphasic APD response in mouse was partly due to dynamic changes in HR during SNS and was exacerbated by β-adrenergic activation. Simulations with species-specific cardiac models revealed that transient APD prolongation in mouse allowed for greater and more rapid CaT responses, suggesting more rapid increases in contractility; conversely, the rabbit heart requires APD shortening to produce optimal inotropic responses. Thus, while the cardiac fight-or-flight response is highly conserved between species, the underlying mechanisms orchestrating these effects differ significantly.
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Affiliation(s)
- Lianguo Wang
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Stefano Morotti
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Srinivas Tapa
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | | | - Yanyan Jiang
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Zhen Wang
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Rachel C Myles
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, Glasgow, UK
| | - Kieran E Brack
- Department of Cardiovascular Sciences, University of Leicester, NIHR Leicester Biomedical Research Centre, Leicester, UK
| | - G André Ng
- Department of Cardiovascular Sciences, University of Leicester, NIHR Leicester Biomedical Research Centre, Leicester, UK
| | - Donald M Bers
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Eleonora Grandi
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
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Vaidyanathan R, Van Ert H, Haq KT, Morotti S, Esch S, McCune EC, Grandi E, Eckhardt LL. Inward Rectifier Potassium Channels (Kir2.x) and Caveolin-3 Domain-Specific Interaction: Implications for Purkinje Cell-Dependent Ventricular Arrhythmias. Circ Arrhythm Electrophysiol 2019; 11:e005800. [PMID: 29326130 DOI: 10.1161/circep.117.005800] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/30/2017] [Indexed: 01/05/2023]
Abstract
BACKGROUND In human cardiac ventricle, IK1 is mainly comprised Kir2.1, but Kir2.2 and Kir2.3 heterotetramers occur and modulate IK1. Long-QT syndrome-9-associated CAV3 mutations cause decreased Kir2.1 current density, but Kir2.x heterotetramers have not been studied. Here, we determine the effect of long-QT syndrome-9-CAV3 mutation F97C on Kir2.x homo- and heterotetramers and model-associated arrhythmia mechanisms. METHODS AND RESULTS Super-resolution microscopy, co-immunoprecipitation, cellular electrophysiology, on-cell Western blotting, and simulation of Purkinje and ventricular myocyte mathematical models were used. Kir2.x isoforms have unique subcellular colocalization in human cardiomyocytes and coimmunoprecipitate with Cav3. F97C-Cav3 decreased peak inward Kir2.2 current density by 50% (-120 mV; P=0.019) and peak outward by 75% (-40 mV; P<0.05) but did not affect Kir2.3 current density. FRET (Förster resonance energy transfer) efficiency for Kir2.2 with Cav3 is high, and on-cell Western blotting demonstrates decreased Kir2.2 membrane expression with F97C-Cav3. Cav3-F97C reduced peak inward and outward current density of Kir2.2/Kir2.1 or Kir2.2/Kir2.3 heterotetramers (P<0.05). Only Cav3 scaffolding and membrane domains co-immunoprecipitation with Kir2.1 and Kir2.2 and Kir2.x-N-terminal Cav3 binding motifs are required for interaction. Mathematical Purkinje, but not ventricular, myocyte model incorporating simulated current reductions, predicts spontaneous delayed after-depolarization-mediated triggered activity. CONCLUSIONS Kir2.x isoforms have a unique intracellular pattern of distribution in association with specific Cav3 domains and that critically depends on interaction with N-terminal Kir2.x Cav3-binding motifs. Long-QT syndrome-9-CAV3 mutation differentially regulates current density and cell surface expression of Kir2.x homomeric and heteromeric channels. Mathematical Purkinje cell model incorporating experimental findings suggests delayed after-depolarization-type triggered activity as a possible arrhythmia mechanism.
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Affiliation(s)
- Ravi Vaidyanathan
- From the Division of Cardiovascular Medicine and the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison (R.V., H.V.E., S.E., E.C.M., L.L.E.); and Department of Pharmacology, University of California Davis (K.T.H., S.M., E.G.)
| | - Hanora Van Ert
- From the Division of Cardiovascular Medicine and the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison (R.V., H.V.E., S.E., E.C.M., L.L.E.); and Department of Pharmacology, University of California Davis (K.T.H., S.M., E.G.)
| | - Kazi T Haq
- From the Division of Cardiovascular Medicine and the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison (R.V., H.V.E., S.E., E.C.M., L.L.E.); and Department of Pharmacology, University of California Davis (K.T.H., S.M., E.G.)
| | - Stefano Morotti
- From the Division of Cardiovascular Medicine and the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison (R.V., H.V.E., S.E., E.C.M., L.L.E.); and Department of Pharmacology, University of California Davis (K.T.H., S.M., E.G.)
| | - Samuel Esch
- From the Division of Cardiovascular Medicine and the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison (R.V., H.V.E., S.E., E.C.M., L.L.E.); and Department of Pharmacology, University of California Davis (K.T.H., S.M., E.G.)
| | - Elise C McCune
- From the Division of Cardiovascular Medicine and the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison (R.V., H.V.E., S.E., E.C.M., L.L.E.); and Department of Pharmacology, University of California Davis (K.T.H., S.M., E.G.)
| | - Eleonora Grandi
- From the Division of Cardiovascular Medicine and the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison (R.V., H.V.E., S.E., E.C.M., L.L.E.); and Department of Pharmacology, University of California Davis (K.T.H., S.M., E.G.)
| | - Lee L Eckhardt
- From the Division of Cardiovascular Medicine and the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison (R.V., H.V.E., S.E., E.C.M., L.L.E.); and Department of Pharmacology, University of California Davis (K.T.H., S.M., E.G.).
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50
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Syed AU, Reddy GR, Ghosh D, Prada MP, Nystoriak MA, Morotti S, Grandi E, Sirish P, Chiamvimonvat N, Hell JW, Santana LF, Xiang YK, Nieves-Cintrón M, Navedo MF. Adenylyl cyclase 5-generated cAMP controls cerebral vascular reactivity during diabetic hyperglycemia. J Clin Invest 2019; 129:3140-3152. [PMID: 31162142 PMCID: PMC6668679 DOI: 10.1172/jci124705] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Elevated blood glucose (hyperglycemia) is a hallmark metabolic abnormality in diabetes. Hyperglycemia is associated with protein kinase A (PKA)-mediated stimulation of L-type Ca2+ channels in arterial myocytes resulting in increased vasoconstriction. However, the mechanisms by which glucose activates PKA remain unclear. Here, we showed that elevating extracellular glucose stimulates cAMP production in arterial myocytes, and that this was specifically dependent on adenylyl cyclase 5 (AC5) activity. Super-resolution imaging suggested nanometer proximity between subpopulations of AC5 and the L-type Ca2+ channel pore-forming subunit CaV1.2. In vitro, in silico, ex vivo and in vivo experiments revealed that this close association is critical for stimulation of L-type Ca2+ channels in arterial myocytes and increased myogenic tone upon acute hyperglycemia. This pathway supported the increase in L-type Ca2+ channel activity and myogenic tone in two animal models of diabetes. Our collective findings demonstrate a unique role for AC5 in PKA-dependent modulation of L-type Ca2+ channel activity and vascular reactivity during acute hyperglycemia and diabetes.
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Affiliation(s)
- Arsalan U Syed
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Gopireddy R Reddy
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Debapriya Ghosh
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Maria Paz Prada
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Matthew A Nystoriak
- Diabetes and Obesity Center, Department of Medicine, University of Louisville, Louisville, Kentucky, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Padmini Sirish
- Department of Internal Medicine, University of California, Davis, Davis, California, USA
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California, Davis, Davis, California, USA.,Department of Internal Medicine, University of California, Davis, Davis, California, USA.,VA Northern California Health Care System, Mather, California, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Luis F Santana
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, California, USA
| | - Yang K Xiang
- Department of Pharmacology, University of California, Davis, Davis, California, USA.,VA Northern California Health Care System, Mather, California, USA
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, Davis, California, USA
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