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Verkerk AO, Wilders R. The Action Potential Clamp Technique as a Tool for Risk Stratification of Sinus Bradycardia Due to Loss-of-Function Mutations in HCN4: An In Silico Exploration Based on In Vitro and In Vivo Data. Biomedicines 2023; 11:2447. [PMID: 37760888 PMCID: PMC10525944 DOI: 10.3390/biomedicines11092447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/30/2023] [Accepted: 08/31/2023] [Indexed: 09/29/2023] Open
Abstract
These days, in vitro functional analysis of gene variants is becoming increasingly important for risk stratification of cardiac ion channelopathies. So far, such risk stratification has been applied to SCN5A, KCNQ1, and KCNH2 gene variants associated with Brugada syndrome and long QT syndrome types 1 and 2, respectively, but risk stratification of HCN4 gene variants related to sick sinus syndrome has not yet been performed. HCN4 is the gene responsible for the hyperpolarization-activated 'funny' current If, which is an important modulator of the spontaneous diastolic depolarization underlying the sinus node pacemaker activity. In the present study, we carried out a risk classification assay on those loss-of-function mutations in HCN4 for which in vivo as well as in vitro data have been published. We used the in vitro data to compute the charge carried by If (Qf) during the diastolic depolarization phase of a prerecorded human sinus node action potential waveform and assessed the extent to which this Qf predicts (1) the beating rate of the comprehensive Fabbri-Severi model of a human sinus node cell with mutation-induced changes in If and (2) the heart rate observed in patients carrying the associated mutation in HCN4. The beating rate of the model cell showed a very strong correlation with Qf from the simulated action potential clamp experiments (R2 = 0.95 under vagal tone). The clinically observed minimum or resting heart rates showed a strong correlation with Qf (R2 = 0.73 and R2 = 0.71, respectively). While a translational perspective remains to be seen, we conclude that action potential clamp on transfected cells, without the need for further voltage clamp experiments and data analysis to determine individual biophysical parameters of If, is a promising tool for risk stratification of sinus bradycardia due to loss-of-function mutations in HCN4. In combination with an If blocker, this tool may also prove useful when applied to human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) obtained from mutation carriers and non-carriers.
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Affiliation(s)
- Arie O. Verkerk
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
- Department of Experimental Cardiology, Heart Center, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Ronald Wilders
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
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2
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Verkerk AO, Wilders R. Human Sinoatrial Node Pacemaker Activity: Role of the Slow Component of the Delayed Rectifier K + Current, I Ks. Int J Mol Sci 2023; 24:7264. [PMID: 37108427 PMCID: PMC10138838 DOI: 10.3390/ijms24087264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/07/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
The pacemaker activity of the sinoatrial node (SAN) has been studied extensively in animal species but is virtually unexplored in humans. Here we assess the role of the slowly activating component of the delayed rectifier K+ current (IKs) in human SAN pacemaker activity and its dependence on heart rate and β-adrenergic stimulation. HEK-293 cells were transiently transfected with wild-type KCNQ1 and KCNE1 cDNA, encoding the α- and β-subunits of the IKs channel, respectively. KCNQ1/KCNE1 currents were recorded both during a traditional voltage clamp and during an action potential (AP) clamp with human SAN-like APs. Forskolin (10 µmol/L) was used to increase the intracellular cAMP level, thus mimicking β-adrenergic stimulation. The experimentally observed effects were evaluated in the Fabbri-Severi computer model of an isolated human SAN cell. Transfected HEK-293 cells displayed large IKs-like outward currents in response to depolarizing voltage clamp steps. Forskolin significantly increased the current density and significantly shifted the half-maximal activation voltage towards more negative potentials. Furthermore, forskolin significantly accelerated activation without affecting the rate of deactivation. During an AP clamp, the KCNQ1/KCNE1 current was substantial during the AP phase, but relatively small during diastolic depolarization. In the presence of forskolin, the KCNQ1/KCNE1 current during both the AP phase and diastolic depolarization increased, resulting in a clearly active KCNQ1/KCNE1 current during diastolic depolarization, particularly at shorter cycle lengths. Computer simulations demonstrated that IKs reduces the intrinsic beating rate through its slowing effect on diastolic depolarization at all levels of autonomic tone and that gain-of-function mutations in KCNQ1 may exert a marked bradycardic effect during vagal tone. In conclusion, IKs is active during human SAN pacemaker activity and has a strong dependence on heart rate and cAMP level, with a prominent role at all levels of autonomic tone.
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Affiliation(s)
- Arie O. Verkerk
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
- Department of Experimental Cardiology, Heart Center, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Ronald Wilders
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
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3
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Young LJ, Antwi-Boasiako S, Ferrall J, Wold LE, Mohler PJ, El Refaey M. Genetic and non-genetic risk factors associated with atrial fibrillation. Life Sci 2022; 299:120529. [PMID: 35385795 PMCID: PMC9058231 DOI: 10.1016/j.lfs.2022.120529] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/08/2022] [Accepted: 03/31/2022] [Indexed: 12/15/2022]
Abstract
Atrial fibrillation (AF) is the most common arrhythmic disorder and its prevalence in the United States is projected to increase to more than twelve million cases in 2030. AF increases the risk of other forms of cardiovascular disease, including stroke. As the incidence of atrial fibrillation increases dramatically with age, it is paramount to elucidate risk factors underlying AF pathogenesis. Here, we review tissue and cellular pathways underlying AF, as well as critical components that impact AF susceptibility including genetic and environmental risk factors. Finally, we provide the latest information on potential links between SARS-CoV-2 and human AF. Improved understanding of mechanistic pathways holds promise in preventative care and early diagnostics, and also introduces novel targeted forms of therapy that might attenuate AF progression and maintenance.
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Affiliation(s)
- Lindsay J Young
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Steve Antwi-Boasiako
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Joel Ferrall
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Loren E Wold
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA; College of Nursing, The Ohio State University, Columbus, OH, USA
| | - Peter J Mohler
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA; Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University, Columbus, OH, USA
| | - Mona El Refaey
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH, USA.
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4
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Ng LCT, Li YX, Van Petegem F, Accili EA. Altered cyclic nucleotide-binding and pore opening in a diseased human HCN4 channel. Biophys J 2022; 121:1166-1183. [PMID: 35219649 PMCID: PMC9034293 DOI: 10.1016/j.bpj.2022.02.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 09/20/2021] [Accepted: 02/22/2022] [Indexed: 11/16/2022] Open
Abstract
A growing number of nonsynonymous mutations in the human HCN4 channel gene, the major component of the funny channel of the sinoatrial node, are associated with disease but how they impact channel structure and function, and, thus, how they result in disease, is not clear for any of them. Here, we study the S672R mutation, in the cyclic nucleotide-binding domain of the channel, which has been associated with an inherited bradycardia in an Italian family. This may be the best studied of all known mutations, yet the underlying molecular and atomistic mechanisms remain unclear and controversial. We combine measurements of binding by isothermal titration calorimetry to a naturally occurring tetramer of the HCN4 C-terminal region with a mathematical model to show that weaker binding of cAMP to the mutant channel contributes to a lower level of facilitation of channel opening at submicromolar ligand concentrations but that, in general, facilitation occurs over a range that is similar between the mutant and wild-type because of enhanced opening of the mutant channel when liganded. We also show that the binding affinity for cGMP, which produces the same maximum facilitation of HCN4 opening as cAMP, is weaker in the mutant HCN4 channel but that, for both wild-type and mutant, high-affinity binding of cGMP occurs in a range of concentrations below 1 μM. Thus, binding of cGMP to the HCN4 channel may be relevant normally in vivo and reduced binding of cGMP, as well as cAMP, to the mutant channel may contribute to the reduced resting heart rate observed in the affected family.
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Affiliation(s)
- Leo C T Ng
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Yue Xian Li
- Department of Mathematics, University of British Columbia, Vancouver, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Eric A Accili
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada.
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5
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Iop L, Iliceto S, Civieri G, Tona F. Inherited and Acquired Rhythm Disturbances in Sick Sinus Syndrome, Brugada Syndrome, and Atrial Fibrillation: Lessons from Preclinical Modeling. Cells 2021; 10:3175. [PMID: 34831398 PMCID: PMC8623957 DOI: 10.3390/cells10113175] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/03/2021] [Accepted: 11/09/2021] [Indexed: 12/12/2022] Open
Abstract
Rhythm disturbances are life-threatening cardiovascular diseases, accounting for many deaths annually worldwide. Abnormal electrical activity might arise in a structurally normal heart in response to specific triggers or as a consequence of cardiac tissue alterations, in both cases with catastrophic consequences on heart global functioning. Preclinical modeling by recapitulating human pathophysiology of rhythm disturbances is fundamental to increase the comprehension of these diseases and propose effective strategies for their prevention, diagnosis, and clinical management. In silico, in vivo, and in vitro models found variable application to dissect many congenital and acquired rhythm disturbances. In the copious list of rhythm disturbances, diseases of the conduction system, as sick sinus syndrome, Brugada syndrome, and atrial fibrillation, have found extensive preclinical modeling. In addition, the electrical remodeling as a result of other cardiovascular diseases has also been investigated in models of hypertrophic cardiomyopathy, cardiac fibrosis, as well as arrhythmias induced by other non-cardiac pathologies, stress, and drug cardiotoxicity. This review aims to offer a critical overview on the effective ability of in silico bioinformatic tools, in vivo animal studies, in vitro models to provide insights on human heart rhythm pathophysiology in case of sick sinus syndrome, Brugada syndrome, and atrial fibrillation and advance their safe and successful translation into the cardiology arena.
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Affiliation(s)
- Laura Iop
- Department of Cardiac Thoracic Vascular Sciences and Public Health, University of Padua, Via Giustiniani, 2, I-35124 Padua, Italy; (S.I.); (G.C.)
| | | | | | - Francesco Tona
- Department of Cardiac Thoracic Vascular Sciences and Public Health, University of Padua, Via Giustiniani, 2, I-35124 Padua, Italy; (S.I.); (G.C.)
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6
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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] [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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7
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Regulation of sinoatrial funny channels by cyclic nucleotides: From adrenaline and I K2 to direct binding of ligands to protein subunits. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 166:12-21. [PMID: 34237319 DOI: 10.1016/j.pbiomolbio.2021.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 06/13/2021] [Accepted: 06/25/2021] [Indexed: 12/27/2022]
Abstract
The funny current, and the HCN channels that form it, are affected by the direct binding of cyclic nucleotides. Binding of these second messengers causes a depolarizing shift of the activation curve, which leads to greater availability of current at physiological membrane voltages. This review outlines a brief history on this regulation and provides some evidence that other cyclic nucleotides, especially cGMP, may be important for the regulation of the funny channel in the heart. Current understanding of the molecular mechanism of cyclic nucleotide regulation is also presented, which includes the notions that full and partial agonism occur as a consequence of negatively cooperative binding. Knowledge gaps, including a potential role of cyclic nucleotide-regulation of the funny current under pathophysiological conditions, are included. The work highlighted here is in dedication to Dario DiFrancesco on his retirement.
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8
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Hoekstra M, van Ginneken ACG, Wilders R, Verkerk AO. HCN4 current during human sinoatrial node-like action potentials. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 166:105-118. [PMID: 34153331 DOI: 10.1016/j.pbiomolbio.2021.05.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/07/2021] [Accepted: 05/14/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND Despite the many studies carried out over the past 40 years, the contribution of the HCN4 encoded hyperpolarization-activated 'funny' current (If) to pacemaker activity in the mammalian sinoatrial node (SAN), and the human SAN in particular, is still controversial and not fully established. OBJECTIVE To study the contribution of If to diastolic depolarization of human SAN cells and its dependence on heart rate, cAMP levels, and atrial load. METHODS HCN4 channels were expressed in human cardiac myocyte progenitor cells (CMPCs) and HCN4 currents assessed using perforated patch-clamp in traditional voltage clamp mode and during action potential clamp with human SAN-like action potential waveforms with 500-1500 ms cycle length, in absence or presence of forskolin to mimic β-adrenergic stimulation and a -15 mV command potential offset to mimic atrial load. RESULTS Forskolin significantly increased the fully-activated HCN4 current density at -140 mV by 14% and shifted the steady-state activation curve by +7.4 mV without affecting its slope. In addition, forskolin significantly accelerated current activation but slowed deactivation. The HCN4 current did not completely deactivate before the subsequent diastolic depolarization during action potential clamp. The amplitude of HCN4 current increased with increasing cycle length, was significantly larger in the presence of forskolin at all cycle lengths, and was significantly increased upon the negative offset to the command potential. CONCLUSIONS If is active during a human SAN action potential waveform and its amplitude is modulated by heart rate, β-adrenergic stimulation, and diastolic voltage range, such that If is under delicate control.
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Affiliation(s)
- Maaike Hoekstra
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Antoni C G van Ginneken
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Ronald Wilders
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
| | - Arie O Verkerk
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands; Department of Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
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9
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Balducci V, Cerbai E. Toward an in vitro human pacemaker. Pflugers Arch 2021; 473:989-990. [PMID: 34032889 DOI: 10.1007/s00424-021-02585-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 05/15/2021] [Accepted: 05/19/2021] [Indexed: 10/21/2022]
Affiliation(s)
- Valentina Balducci
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Elisabetta Cerbai
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy.
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10
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Giannetti F, Benzoni P, Campostrini G, Milanesi R, Bucchi A, Baruscotti M, Dell'Era P, Rossini A, Barbuti A. A detailed characterization of the hyperpolarization-activated "funny" current (I f) in human-induced pluripotent stem cell (iPSC)-derived cardiomyocytes with pacemaker activity. Pflugers Arch 2021; 473:1009-1021. [PMID: 33934225 PMCID: PMC8245366 DOI: 10.1007/s00424-021-02571-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 04/01/2021] [Accepted: 04/19/2021] [Indexed: 01/09/2023]
Abstract
Properties of the funny current (If) have been studied in several animal and cellular models, but so far little is known concerning its properties in human pacemaker cells. This work provides a detailed characterization of If in human-induced pluripotent stem cell (iPSC)–derived pacemaker cardiomyocytes (pCMs), at different time points. Patch-clamp analysis showed that If density did not change during differentiation; however, after day 30, it activates at more negative potential and with slower time constants. These changes are accompanied by a slowing in beating rate. If displayed the voltage-dependent block by caesium and reversed (Erev) at − 22 mV, compatibly with the 3:1 K+/Na+ permeability ratio. Lowering [Na+]o (30 mM) shifted the Erev to − 39 mV without affecting conductance. Increasing [K+]o (30 mM) shifted the Erev to − 15 mV with a fourfold increase in conductance. pCMs express mainly HCN4 and HCN1 together with the accessory subunits CAV3, KCR1, MiRP1, and SAP97 that contribute to the context-dependence of If. Autonomic agonists modulated the diastolic depolarization, and thus rate, of pCMs. The adrenergic agonist isoproterenol induced rate acceleration and a positive shift of If voltage-dependence (EC50 73.4 nM). The muscarinic agonists had opposite effects (Carbachol EC50, 11,6 nM). Carbachol effect was however small but it could be increased by pre-stimulation with isoproterenol, indicating low cAMP levels in pCMs. In conclusion, we demonstrated that pCMs display an If with the physiological properties expected by pacemaker cells and may thus represent a suitable model for studying human If-related sinus arrhythmias.
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Affiliation(s)
- Federica Giannetti
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy
| | - Patrizia Benzoni
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy
| | - Giulia Campostrini
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy
- Department of Anatomy and Embryology, Leiden University Medical Center, Einthovenweg 20, 2333ZC, Leiden, The Netherlands
| | - Raffaella Milanesi
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy
- Dipartimento di Medicina Veterinaria, Università degli Studi di Milano, Via dell'Università 6, 26900, Lodi, Italy
| | - Annalisa Bucchi
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy
| | - Mirko Baruscotti
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy
| | - Patrizia Dell'Era
- Cellular Fate Reprogramming Unit, Department of Molecular and Translational Medicine, University of Brescia, viale Europa 11, 25123, Brescia, Italy
| | - Alessandra Rossini
- Institute for Biomedicine, Eurac Research, Affiliated Institute of the University of Lübeck, Viale Druso 1, 39100, Bolzano, Italy
| | - Andrea Barbuti
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy.
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11
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Amstetter D, Badt F, Rubi L, Bittner RE, Ebner J, Uhrin P, Hilber K, Koenig X, Todt H. The bradycardic agent ivabradine decreases conduction velocity in the AV node and in the ventricles in-vivo. Eur J Pharmacol 2021; 893:173818. [PMID: 33345856 DOI: 10.1016/j.ejphar.2020.173818] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 12/02/2020] [Accepted: 12/10/2020] [Indexed: 10/22/2022]
Abstract
Ivabradine blocks hyperpolarisation-activated cyclic nucleotide-gated (HCN) channels, thereby lowering the heart rate, an action that is used clinically for the treatment of heart failure and angina pectoris. We and others have shown previously that ivabradine, in addition to its HCN channel blocking activity, also inhibits voltage-gated Na channels in vitro at concentrations that may be clinically relevant. Such action may reduce conduction velocity in cardiac atria and ventricles. Here, we explore the effect of administration of ivabradine on parameters of ventricular conduction and repolarization in the surface ECG of anesthetized mice. We found that 5 min after i.p. administration of 10 mg/kg ivabradine spontaneous heart rate had declined by ~13%, which is within the range observed in human clinical studies. At the same time a significant increase in QRS duration by ~18% was observed, suggesting a reduction in ventricular conduction velocity. During transesophageal pacing at heart rates between 100 and 220 beats/min there was no obvious rate-dependence of ivabradine-induced QRS prolongation. On the other hand, ivabradine produced substantial rate-dependent slowing of AV nodal conduction. We conclude that ivabradine prolongs conduction in the AV-node and in the ventricles in vivo.
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Affiliation(s)
- Daniel Amstetter
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Florian Badt
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Lena Rubi
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Reginald E Bittner
- Neuromuscular Research Department, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Janine Ebner
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Pavel Uhrin
- Department of Vascular Biology and Thrombosis Research, Center for Physiology and Pharmacology, Austria
| | - Karlheinz Hilber
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Xaver Koenig
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Hannes Todt
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria.
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12
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Varró A, Tomek J, Nagy N, Virág L, Passini E, Rodriguez B, Baczkó I. Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior. Physiol Rev 2020; 101:1083-1176. [PMID: 33118864 DOI: 10.1152/physrev.00024.2019] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.
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Affiliation(s)
- András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - Jakub Tomek
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Elisa Passini
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
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13
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Abstract
Cardiac pacemaking is a most fundamental cardiac function, thoroughly investigated for decades with a multiscale approach at organ, tissue, cell and molecular levels, to clarify the basic mechanisms underlying generation and control of cardiac rhythm. Understanding the processes involved in pacemaker activity is of paramount importance for a basic physiological knowledge, but also as a way to reveal details of pathological dysfunctions useful in the perspective of a therapeutic approach. Among the mechanisms involved in pacemaking, the "funny" (If) current has properties most specifically fitting the requirements for generation and control of repetitive activity, and has consequently received the most attention in studies of the pacemaker function. Present knowledge of the basic mechanisms of pacemaking and the properties of funny channels has led to important developments of clinical relevance. These include: (1) the successful development of heart rate-reducing agents, such as ivabradine, able to control cardiac rhythm and useful in the treatment of diseases such as coronary artery disease, heart failure and tachyarrhythmias; (2) the understanding of the genetic basis of disorders of cardiac rhythm caused by HCN channelopathies; (3) the design of strategies to implement biological pacemakers based on transfer of HCN channels or of stem cell-derived pacemaker cells expressing If, with the ultimate goal to replace electronic devices. In this review, I will give a brief historical account of the discovery of the funny current and the development of the concept of If-based pacemaking, in the context of a wider, more complex model of cardiac rhythmic function.
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Affiliation(s)
- Dario DiFrancesco
- Department of Biosciences, University of Milano, IBF-CNR University of Milano Unit, Milan, Italy
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14
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Kaczmarek K, Klingenheben T, Poddebska I, Urbanek I, Wranicz JK, Cygankiewicz I, Ptaszyński P. Baseline intrinsic heart rate and response to ivabradine treatment in patients with inappropriate sinus tachycardia. Ann Noninvasive Electrocardiol 2019; 25:e12709. [PMID: 31595620 PMCID: PMC7358846 DOI: 10.1111/anec.12709] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 09/14/2019] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Treatment with ivabradine became a new therapeutic alternative for patients with inappropriate sinus tachycardia (IST). The aim was to determine a relation between intrinsic heart rate (IHR) and response to ivabradine treatment. METHODS Twenty-seven patients (mean age 37 ± 11; 23 women) with symptomatic IST despite medical treatment were recruited into the study. Resting ECG, 24-hr ECG monitoring (24hECG), exercise treadmill test, and symptoms evaluation were performed initially and after 60 days on ivabradine. IHR was acquired at baseline after pharmacological autonomic blockade. RESULTS Nineteen patients (70%) were classified as abnormal IHR group (AIHR) while eight showed normal IHR (NIHR). No significant differences in ECG parameters were found between NIHR and AIHR subgroups, while baseline exercise capacity was higher in AIHR patients (10.9 vs. 9.5 METs, p < .05). Ivabradine treatment resulted in significant reduction in resting heart rate, average 24hECG heart rate, improvement in exercise capacity and reduction of symptoms in both subgroups. Nevertheless, favorable influence of ivabradine was significantly more exaggerated in AIHR subgroup (HR 116 vs. 90 bpm, av. HR 98 vs. 79 bpm, 10.9 vs. 13.6 METS, EHRA score 3.1 vs. 1.1, p < .001 for all) than in NIHR patients (HR 112 vs. 98 bpm, av. HR 97 vs. 88 bpm, 9.5 vs. 11.1 METs, EHRA score 3.1 vs. 1.9; p < .05 for all). CONCLUSIONS Intrinsic heart rate may be useful in predicting response to ivabradine in patients with IST. More intense response to ivabradine in patients with AIHR may be attributed to different pathophysiological mechanisms underlying IST in AIHR and NIHR groups.
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Affiliation(s)
| | | | - Izabela Poddebska
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
| | - Irmina Urbanek
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
| | - Jerzy K Wranicz
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
| | - Iwona Cygankiewicz
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
| | - Pawel Ptaszyński
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
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15
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Nakano Y, Ochi H, Sairaku A, Onohara Y, Tokuyama T, Motoda C, Matsumura H, Tomomori S, Amioka M, Hironobe N, Ohkubo Y, Okamura S, Makita N, Yoshida Y, Chayama K, Kihara Y. HCN4 Gene Polymorphisms Are Associated With Occurrence of Tachycardia-Induced Cardiomyopathy in Patients With Atrial Fibrillation. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2019; 11:e001980. [PMID: 29987112 DOI: 10.1161/circgen.117.001980] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Accepted: 06/08/2018] [Indexed: 11/16/2022]
Abstract
BACKGROUND Tachycardia-induced cardiomyopathy (TIC) is a reversible cardiomyopathy induced by tachyarrhythmia, and the genetic background of the TIC is not well understood. The hyperpolarization-activated cyclic nucleotide-gated channel gene HCN4 is highly expressed in the conduction system where it is involved in heart rate control. We speculated that the HCN4 gene is associated with TIC. METHODS We enrolled 930 Japanese patients with atrial fibrillation (AF) for screening, 350 Japanese patients with AF for replication, and 1635 non-AF controls. In the screening AF set, we compared HCN4 single-nucleotide polymorphism genotypes between AF subjects with TIC (TIC, n=73) and without TIC (non-TIC, n=857). Of 17 HCN4 gene-tag single-nucleotide polymorphisms, rs7172796, rs2680344, rs7164883, rs11631816, and rs12905211 were significantly associated with TIC. Among them, only rs7164883 was independently associated with TIC after conditional analysis (TIC versus non-TIC: minor allele frequency, 26.0% versus 9.7%; P=1.62×10-9; odds ratio=3.2). RESULTS We confirmed this association of HCN4 single-nucleotide polymorphism rs7164883 with TIC in the replication set (TIC=41 and non-TIC=309; minor allele frequency, 28% versus 9.9%; P=1.94×10-6; odds ratio=3.6). The minor allele frequency of rs7164883 was similar in patients with AF and non-AF controls (11% versus 10.9%; P=0.908). CONCLUSIONS The HCN4 gene single-nucleotide polymorphism rs7164883 may be a new genetic marker for TIC in patients with AF.
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Affiliation(s)
- Yukiko Nakano
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.). .,Laboratory for Digestive Diseases, RIKEN Center for Integrative Medical Sciences, Hiroshima, Japan (Y.N., H.O., K.C.)
| | - Hidenori Ochi
- Laboratory for Digestive Diseases, RIKEN Center for Integrative Medical Sciences, Hiroshima, Japan (Y.N., H.O., K.C.).,Liver Research Project Center Hiroshima University, Hiroshima, Japan (H.O., K.C.).,Department of Internal Medicine, Chuden Hospital, The Chugoku Electric Power Company, Japan (H.O.).,Department of Gastroenterology and Metabolism, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (H.O., K.C.)
| | - Akinori Sairaku
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Yuko Onohara
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Takehito Tokuyama
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Chikaaki Motoda
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Hiroya Matsumura
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Shunsuke Tomomori
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Michitaka Amioka
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Naoya Hironobe
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Yousaku Ohkubo
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Shou Okamura
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
| | - Naomasa Makita
- Department of Molecular Physiology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan (N.M.)
| | - Yukihiko Yoshida
- Department of Cardiology, Japanese Red Cross Nagoya Daini Hospital, Nagoya, Japan (Y.Y.)
| | - Kazuaki Chayama
- Laboratory for Digestive Diseases, RIKEN Center for Integrative Medical Sciences, Hiroshima, Japan (Y.N., H.O., K.C.).,Liver Research Project Center Hiroshima University, Hiroshima, Japan (H.O., K.C.).,Department of Gastroenterology and Metabolism, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (H.O., K.C.)
| | - Yasuki Kihara
- Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan (Y.N., A.S., Y.O., T.T., C.M., H.M., S.T., M.A., N.H., S.O., Y.K.)
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16
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Marini C, Porro A, Rastetter A, Dalle C, Rivolta I, Bauer D, Oegema R, Nava C, Parrini E, Mei D, Mercer C, Dhamija R, Chambers C, Coubes C, Thévenon J, Kuentz P, Julia S, Pasquier L, Dubourg C, Carré W, Rosati A, Melani F, Pisano T, Giardino M, Innes AM, Alembik Y, Scheidecker S, Santos M, Figueiroa S, Garrido C, Fusco C, Frattini D, Spagnoli C, Binda A, Granata T, Ragona F, Freri E, Franceschetti S, Canafoglia L, Castellotti B, Gellera C, Milanesi R, Mancardi MM, Clark DR, Kok F, Helbig KL, Ichikawa S, Sadler L, Neupauerová J, Laššuthova P, Šterbová K, Laridon A, Brilstra E, Koeleman B, Lemke JR, Zara F, Striano P, Soblet J, Smits G, Deconinck N, Barbuti A, DiFrancesco D, LeGuern E, Guerrini R, Santoro B, Hamacher K, Thiel G, Moroni A, DiFrancesco JC, Depienne C. HCN1 mutation spectrum: from neonatal epileptic encephalopathy to benign generalized epilepsy and beyond. Brain 2019; 141:3160-3178. [PMID: 30351409 DOI: 10.1093/brain/awy263] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 08/09/2018] [Indexed: 12/15/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels control neuronal excitability and their dysfunction has been linked to epileptogenesis but few individuals with neurological disorders related to variants altering HCN channels have been reported so far. In 2014, we described five individuals with epileptic encephalopathy due to de novo HCN1 variants. To delineate HCN1-related disorders and investigate genotype-phenotype correlations further, we assembled a cohort of 33 unpublished patients with novel pathogenic or likely pathogenic variants: 19 probands carrying 14 different de novo mutations and four families with dominantly inherited variants segregating with epilepsy in 14 individuals, but not penetrant in six additional individuals. Sporadic patients had epilepsy with median onset at age 7 months and in 36% the first seizure occurred during a febrile illness. Overall, considering familial and sporadic patients, the predominant phenotypes were mild, including genetic generalized epilepsies and genetic epilepsy with febrile seizures plus (GEFS+) spectrum. About 20% manifested neonatal/infantile onset otherwise unclassified epileptic encephalopathy. The study also included eight patients with variants of unknown significance: one adopted patient had two HCN1 variants, four probands had intellectual disability without seizures, and three individuals had missense variants inherited from an asymptomatic parent. Of the 18 novel pathogenic missense variants identified, 12 were associated with severe phenotypes and clustered within or close to transmembrane domains, while variants segregating with milder phenotypes were located outside transmembrane domains, in the intracellular N- and C-terminal parts of the channel. Five recurrent variants were associated with similar phenotypes. Using whole-cell patch-clamp, we showed that the impact of 12 selected variants ranged from complete loss-of-function to significant shifts in activation kinetics and/or voltage dependence. Functional analysis of three different substitutions altering Gly391 revealed that these variants had different consequences on channel biophysical properties. The Gly391Asp variant, associated with the most severe, neonatal phenotype, also had the most severe impact on channel function. Molecular dynamics simulation on channel structure showed that homotetramers were not conducting ions because the permeation path was blocked by cation(s) strongly complexed to the Asp residue, whereas heterotetramers showed an instantaneous current component possibly linked to deformation of the channel pore. In conclusion, our results considerably expand the clinical spectrum related to HCN1 variants to include common generalized epilepsy phenotypes and further illustrate how HCN1 has a pivotal function in brain development and control of neuronal excitability.
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Affiliation(s)
- Carla Marini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Viale Pieraccini 24, Florence, Italy.,EuroEPINOMICS RES Consortium
| | | | - Agnès Rastetter
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Carine Dalle
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Ilaria Rivolta
- School of Medicine and Surgery, University Milano-Bicocca, Monza, Italy
| | - Daniel Bauer
- Computational Biology and Simulation Group, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Renske Oegema
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Caroline Nava
- EuroEPINOMICS RES Consortium.,Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France.,AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Département de Génétique, Paris, France
| | - Elena Parrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Viale Pieraccini 24, Florence, Italy
| | - Davide Mei
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Viale Pieraccini 24, Florence, Italy
| | - Catherine Mercer
- Wessex Clinical Genetics Service, Princess Anne Hospital, Southampton, UK
| | - Radhika Dhamija
- Department of Clinical Genomics and Neurology, Mayo Clinic, Phoenix, AZ, USA
| | - Chelsea Chambers
- Department of Neurosciences, University of Virginia, Charlottesville, VA, USA
| | - Christine Coubes
- Département de Génétique Médicale, Maladies Rares et Médecine Personnalisée, Hôpital Arnaud de Villeneuve, Montpellier, France
| | - Julien Thévenon
- FHU-TRANSLAD, Université de Bourgogne/CHU Dijon and INSERM UMR 1231 GAD team, Genetics of Developmental Anomalies, Université de Bourgogne-Franche Comté, Dijon, France
| | - Paul Kuentz
- FHU-TRANSLAD, Université de Bourgogne/CHU Dijon and INSERM UMR 1231 GAD team, Genetics of Developmental Anomalies, Université de Bourgogne-Franche Comté, Dijon, France.,Génétique Biologique Histologie, CHRU de Besançon, Besançon, France
| | - Sophie Julia
- Service de génétique médicale, Pôle de biologie, CHU de Toulouse - Hôpital Purpan, Toulouse, France
| | - Laurent Pasquier
- Service de Génétique Clinique, Centre Référence Déficiences Intellectuelles de causes rares (CRDI), CHU Rennes, Rennes, France
| | - Christèle Dubourg
- Laboratoire de Génétique Moléculaire et Génomique, CHU de Rennes, Rennes, France
| | - Wilfrid Carré
- Laboratoire de Génétique Moléculaire et Génomique, CHU de Rennes, Rennes, France
| | - Anna Rosati
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Viale Pieraccini 24, Florence, Italy
| | - Federico Melani
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Viale Pieraccini 24, Florence, Italy
| | - Tiziana Pisano
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Viale Pieraccini 24, Florence, Italy
| | - Maria Giardino
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Viale Pieraccini 24, Florence, Italy
| | - A Micheil Innes
- Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Yves Alembik
- Laboratoires de génétique, Institut de génétique médicale d'Alsace, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Sophie Scheidecker
- Laboratoires de génétique, Institut de génétique médicale d'Alsace, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Manuela Santos
- Neuropediatric Department, Centro Hospitalar do Porto, Porto, Portugal
| | - Sonia Figueiroa
- Neuropediatric Department, Centro Hospitalar do Porto, Porto, Portugal
| | - Cristina Garrido
- Neuropediatric Department, Centro Hospitalar do Porto, Porto, Portugal
| | - Carlo Fusco
- Azienda Unità Sanitaria Locale - IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Daniele Frattini
- Azienda Unità Sanitaria Locale - IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Carlotta Spagnoli
- Azienda Unità Sanitaria Locale - IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Anna Binda
- School of Medicine and Surgery, University Milano-Bicocca, Monza, Italy
| | - Tiziana Granata
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | | | - Elena Freri
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | | | | | | | - Cinzia Gellera
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Raffaella Milanesi
- Department of Biosciences, The PaceLab, Università degli Studi di Milano, Milan, Italy
| | - Maria Margherita Mancardi
- Child Neuropsychiatry Unit, Department of Medical and Surgical Neurosciences and Rehabilitation, IRCCS Istituto Giannina Gaslini, Genova, Italy
| | | | - Fernando Kok
- Mendelics Genomic Analysis, Sao Paulo, SP, Brazil
| | - Katherine L Helbig
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Shoji Ichikawa
- Department of Clinical Diagnostics, Ambry Genetics, Aliso Viejo, CA, USA
| | - Laurie Sadler
- Division of Genetics, Department of Pediatrics, Oishei Children's Hospital, Jacobs School of Medicine and Biomedical Sciences, University of Buffalo, State University of New York, Buffalo, NY, USA
| | - Jana Neupauerová
- Department of Child Neurology, Charles University 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic
| | - Petra Laššuthova
- Department of Child Neurology, Charles University 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic
| | - Katalin Šterbová
- EuroEPINOMICS RES Consortium.,Department of Child Neurology, Charles University 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic
| | - Annick Laridon
- Department of Neurology, Academic Center for Epileptology, Kempenhaeghe/Maastricht University Medical Center, Heeze, The Netherlands
| | - Eva Brilstra
- EuroEPINOMICS RES Consortium.,Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bobby Koeleman
- EuroEPINOMICS RES Consortium.,Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Johannes R Lemke
- EuroEPINOMICS RES Consortium.,Institute of Human Genetics, University of Leipzig Hospitals and Clinics, Leipzig, Germany
| | - Federico Zara
- Laboratory of Neurogenetics and Neuroscience, Institute G Gaslini, Genova, Italy
| | - Pasquale Striano
- EuroEPINOMICS RES Consortium.,Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 'G Gaslini' Institute, Genova, Italy
| | - Julie Soblet
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Université Libre de Bruxelles, Brussels, Belgium.,Department of Genetics, Hôpital Erasme ULB Center of Human Genetics, Université Libre de Bruxelles, Brussels, Belgium.,Interuniversity Institute of Bioinformatics in Brussels, Université Libre de Bruxelles, Brussels, Belgium
| | - Guillaume Smits
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Université Libre de Bruxelles, Brussels, Belgium.,Department of Genetics, Hôpital Erasme ULB Center of Human Genetics, Université Libre de Bruxelles, Brussels, Belgium.,Interuniversity Institute of Bioinformatics in Brussels, Université Libre de Bruxelles, Brussels, Belgium
| | - Nicolas Deconinck
- Department of Pediatric Neurology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, ULB, Brussels, Belgium
| | - Andrea Barbuti
- Department of Biosciences, The PaceLab, Università degli Studi di Milano, Milan, Italy
| | - Dario DiFrancesco
- Department of Biosciences, The PaceLab, Università degli Studi di Milano, Milan, Italy
| | - Eric LeGuern
- EuroEPINOMICS RES Consortium.,Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France.,AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Département de Génétique, Paris, France
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department, A Meyer Children's Hospital, University of Florence, Viale Pieraccini 24, Florence, Italy.,EuroEPINOMICS RES Consortium
| | - Bina Santoro
- Department of Neuroscience, Columbia University, New York, NY, USA
| | - Kay Hamacher
- Computational Biology and Simulation Group, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Gerhard Thiel
- Membrane Biophysics, Deparment of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Anna Moroni
- Department of Biosciences, University of Milan, Milan, Italy
| | - Jacopo C DiFrancesco
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.,Department of Neurology, San Gerardo Hospital, University Milano-Bicocca, Monza, Italy
| | - Christel Depienne
- EuroEPINOMICS RES Consortium.,Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France.,IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France.,Institute of Human Genetics, University Hospital Essen, University Duisburg-Essen, Essen, Germany
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17
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DiFrancesco JC, Castellotti B, Milanesi R, Ragona F, Freri E, Canafoglia L, Franceschetti S, Ferrarese C, Magri S, Taroni F, Costa C, Labate A, Gambardella A, Solazzi R, Binda A, Rivolta I, Di Gennaro G, Casciato S, D’Incerti L, Barbuti A, DiFrancesco D, Granata T, Gellera C. HCN ion channels and accessory proteins in epilepsy: genetic analysis of a large cohort of patients and review of the literature. Epilepsy Res 2019; 153:49-58. [DOI: 10.1016/j.eplepsyres.2019.04.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/01/2019] [Accepted: 04/08/2019] [Indexed: 11/28/2022]
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18
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Baruscotti M, Bucchi A, Milanesi R, Paina M, Barbuti A, Gnecchi-Ruscone T, Bianco E, Vitali-Serdoz L, Cappato R, DiFrancesco D. A gain-of-function mutation in the cardiac pacemaker HCN4 channel increasing cAMP sensitivity is associated with familial Inappropriate Sinus Tachycardia. Eur Heart J 2019; 38:280-288. [PMID: 28182231 DOI: 10.1093/eurheartj/ehv582] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 10/01/2015] [Accepted: 10/07/2015] [Indexed: 01/09/2023] Open
Affiliation(s)
- Mirko Baruscotti
- Department of Biosciences, The PaceLab and 'Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata', Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy
| | - Annalisa Bucchi
- Department of Biosciences, The PaceLab and 'Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata', Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy
| | - Raffaella Milanesi
- Department of Biosciences, The PaceLab and 'Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata', Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy
| | - Manuel Paina
- Department of Biosciences, The PaceLab and 'Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata', Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy
| | - Andrea Barbuti
- Department of Biosciences, The PaceLab and 'Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata', Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy
| | | | - Elisabetta Bianco
- Cardiovascular Department, 'Ospedali Riuniti di Trieste', University Hospital, Trieste, Italy
| | | | | | - Dario DiFrancesco
- Department of Biosciences, The PaceLab and 'Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata', Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy
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19
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Byun JA, Melacini G. NMR methods to dissect the molecular mechanisms of disease-related mutations (DRMs): Understanding how DRMs remodel functional free energy landscapes. Methods 2018; 148:19-27. [DOI: 10.1016/j.ymeth.2018.05.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 05/19/2018] [Accepted: 05/22/2018] [Indexed: 10/14/2022] Open
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20
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Campostrini G, DiFrancesco JC, Castellotti B, Milanesi R, Gnecchi-Ruscone T, Bonzanni M, Bucchi A, Baruscotti M, Ferrarese C, Franceschetti S, Canafoglia L, Ragona F, Freri E, Labate A, Gambardella A, Costa C, Gellera C, Granata T, Barbuti A, DiFrancesco D. A Loss-of-Function HCN4 Mutation Associated With Familial Benign Myoclonic Epilepsy in Infancy Causes Increased Neuronal Excitability. Front Mol Neurosci 2018; 11:269. [PMID: 30127718 PMCID: PMC6089338 DOI: 10.3389/fnmol.2018.00269] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 07/16/2018] [Indexed: 01/03/2023] Open
Abstract
HCN channels are highly expressed and functionally relevant in neurons and increasing evidence demonstrates their involvement in the etiology of human epilepsies. Among HCN isoforms, HCN4 is important in cardiac tissue, where it underlies pacemaker activity. Despite being expressed also in deep structures of the brain, mutations of this channel functionally shown to be associated with epilepsy have not been reported yet. Using Next Generation Sequencing for the screening of patients with idiopathic epilepsy, we identified the p.Arg550Cys (c.1648C>T) heterozygous mutation on HCN4 in two brothers affected by benign myoclonic epilepsy of infancy. Functional characterization in heterologous expression system and in neurons showed that the mutation determines a loss of function of HCN4 contribution to activity and an increase of neuronal discharge, potentially predisposing to epilepsy. Expressed in cardiomyocytes, mutant channels activate at slightly more negative voltages than wild-type (WT), in accordance with borderline bradycardia. While HCN4 variants have been frequently associated with cardiac arrhythmias, these data represent the first experimental evidence that functional alteration of HCN4 can also be involved in human epilepsy through a loss-of-function effect and associated increased neuronal excitability. Since HCN4 appears to be highly expressed in deep brain structures only early during development, our data provide a potential explanation for a link between dysfunctional HCN4 and infantile epilepsy. These findings suggest that it may be useful to include HCN4 screening to extend the knowledge of the genetic causes of infantile epilepsies, potentially paving the way for the identification of innovative therapeutic strategies.
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Affiliation(s)
- Giulia Campostrini
- Molecular Physiology and Neurobiology, The PaceLab, Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | - Jacopo C DiFrancesco
- Clinical Neurophysiology and Epilepsy Center, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.,Laboratory of Neurobiology, Department of Neurology, Milan Center for Neuroscience, San Gerardo Hospital, University of Milano-Bicocca, Monza, Italy
| | - Barbara Castellotti
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Raffaella Milanesi
- Molecular Physiology and Neurobiology, The PaceLab, Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | | | - Mattia Bonzanni
- Molecular Physiology and Neurobiology, The PaceLab, Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | - Annalisa Bucchi
- Molecular Physiology and Neurobiology, The PaceLab, Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | - Mirko Baruscotti
- Molecular Physiology and Neurobiology, The PaceLab, Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | - Carlo Ferrarese
- Laboratory of Neurobiology, Department of Neurology, Milan Center for Neuroscience, San Gerardo Hospital, University of Milano-Bicocca, Monza, Italy
| | - Silvana Franceschetti
- Clinical Neurophysiology and Epilepsy Center, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Laura Canafoglia
- Clinical Neurophysiology and Epilepsy Center, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Francesca Ragona
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Elena Freri
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Angelo Labate
- Institute of Neurology, Università degli Studi Magna Græcia di Catanzaro, Catanzaro, Italy
| | - Antonio Gambardella
- Institute of Neurology, Università degli Studi Magna Græcia di Catanzaro, Catanzaro, Italy
| | - Cinzia Costa
- Neurology Unit, Ospedale S. Maria della Misericordia, Department of Medicine, University of Perugia, Perugia, Italy
| | - Cinzia Gellera
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Tiziana Granata
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Andrea Barbuti
- Molecular Physiology and Neurobiology, The PaceLab, Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | - Dario DiFrancesco
- Molecular Physiology and Neurobiology, The PaceLab, Department of Biosciences, Università degli Studi di Milano, Milan, Italy
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21
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Tsai CT. HCN4 Gene Polymorphisms and Tachycardia-Induced Cardiomyopathy. Circ Genom Precis Med 2018; 11:e002223. [DOI: 10.1161/circgen.118.002223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Chia-Ti Tsai
- Division of Cardiology, Department of Internal Medicine, National Taiwan University College of Medicine and Hospital, Taipei
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22
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Mesirca P, Torrente AG, Bidaud I, Baudot M, Nargeot J, Mangoni ME. [Genesis of cardiac sinus automaticity and therapeutic perspectives]. ARCHIVES DES MALADIES DU COEUR ET DES VAISSEAUX. PRATIQUE 2018; 2018:35-39. [PMID: 30333689 PMCID: PMC6186439 DOI: 10.1016/j.amcp.2018.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Affiliation(s)
- P Mesirca
- CNRS, Inserm, département de physiologie, université de Montpellier, institut de génomique fonctionnelle, 141, rue de la Cardonille, 34094 Montpellier, France
| | - A-G Torrente
- CNRS, Inserm, département de physiologie, université de Montpellier, institut de génomique fonctionnelle, 141, rue de la Cardonille, 34094 Montpellier, France
| | - I Bidaud
- CNRS, Inserm, département de physiologie, université de Montpellier, institut de génomique fonctionnelle, 141, rue de la Cardonille, 34094 Montpellier, France
| | - M Baudot
- CNRS, Inserm, département de physiologie, université de Montpellier, institut de génomique fonctionnelle, 141, rue de la Cardonille, 34094 Montpellier, France
| | - J Nargeot
- CNRS, Inserm, département de physiologie, université de Montpellier, institut de génomique fonctionnelle, 141, rue de la Cardonille, 34094 Montpellier, France
| | - M-E Mangoni
- CNRS, Inserm, département de physiologie, université de Montpellier, institut de génomique fonctionnelle, 141, rue de la Cardonille, 34094 Montpellier, France
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23
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Becker F, Reid CA, Hallmann K, Tae HS, Phillips AM, Teodorescu G, Weber YG, Kleefuss-Lie A, Elger C, Perez-Reyes E, Petrou S, Kunz WS, Lerche H, Maljevic S. Functional variants in HCN4 and CACNA1H may contribute to genetic generalized epilepsy. Epilepsia Open 2017; 2:334-342. [PMID: 29588962 PMCID: PMC5862120 DOI: 10.1002/epi4.12068] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2017] [Indexed: 01/11/2023] Open
Abstract
Objective Genetic generalized epilepsy (GGE) encompasses seizure disorders characterized by spike‐and‐wave discharges (SWD) originating within thalamo‐cortical circuits. Hyperpolarization‐activated (HCN) and T‐type Ca2+ channels are key modulators of rhythmic activity in these brain regions. Here, we screened HCN4 and CACNA1H genes for potentially contributory variants and provide their functional analysis. Methods Targeted gene sequencing was performed in 20 unrelated familial cases with different subtypes of GGE, and the results confirmed in 230 ethnically matching controls. Selected variants in CACNA1H and HCN4 were functionally assessed in tsA201 cells and Xenopus laevis oocytes, respectively. Results We discovered a novel CACNA1H (p.G1158S) variant in two affected members of a single family. One of them also carried an HCN4 (p.P1117L) variant inherited from the unaffected mother. In a separate family, an HCN4 variant (p.E153G) was identified in one of several affected members. Voltage‐clamp analysis of CACNA1H (p.G1158S) revealed a small but significant gain‐of‐function, including increased current density and a depolarizing shift of steady‐state inactivation. HCN4 p.P1117L and p.G153E both caused a hyperpolarizing shift in activation and reduced current amplitudes, resulting in a loss‐of‐function. Significance Our results are consistent with a model suggesting cumulative contributions of subtle functional variations in ion channels to seizure susceptibility and GGE.
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Affiliation(s)
- Felicitas Becker
- Department of Neurology and Epileptology Hertie-Institute for Clinical Brain-Research University of Tübingen Tübingen Germany.,RKU-University Neurology Clinic of Ulm Ulm Germany
| | - Christopher A Reid
- The Florey Institute of Neuroscience and Mental Health Melbourne Victoria Australia
| | - Kerstin Hallmann
- Department of Neurology and Epileptology University of Bonn Medical Center Bonn Germany
| | - Han-Shen Tae
- The Florey Institute of Neuroscience and Mental Health Melbourne Victoria Australia.,Present address: Illawarra Health and Medical Research Institute (IHMRI) University of Wollongong Wollongong New South Wales Australia
| | - A Marie Phillips
- The Florey Institute of Neuroscience and Mental Health Melbourne Victoria Australia.,School of Biosciences The University of Melbourne Melbourne Victoria Australia
| | - Georgeta Teodorescu
- Department of Neurology and Epileptology Hertie-Institute for Clinical Brain-Research University of Tübingen Tübingen Germany
| | - Yvonne G Weber
- Department of Neurology and Epileptology Hertie-Institute for Clinical Brain-Research University of Tübingen Tübingen Germany
| | - Ailing Kleefuss-Lie
- Department of Neurology and Epileptology University of Bonn Medical Center Bonn Germany
| | - Christian Elger
- Department of Neurology and Epileptology University of Bonn Medical Center Bonn Germany
| | - Edward Perez-Reyes
- Department of Pharmacology University of Virginia Charlottesville Virginia U.S.A
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health Melbourne Victoria Australia
| | - Wolfram S Kunz
- Department of Neurology and Epileptology University of Bonn Medical Center Bonn Germany
| | - Holger Lerche
- Department of Neurology and Epileptology Hertie-Institute for Clinical Brain-Research University of Tübingen Tübingen Germany
| | - Snezana Maljevic
- Department of Neurology and Epileptology Hertie-Institute for Clinical Brain-Research University of Tübingen Tübingen Germany.,The Florey Institute of Neuroscience and Mental Health Melbourne Victoria Australia
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24
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Hategan L, Csányi B, Ördög B, Kákonyi K, Tringer A, Kiss O, Orosz A, Sághy L, Nagy I, Hegedűs Z, Rudas L, Széll M, Varró A, Forster T, Sepp R. A novel ‘splice site’ HCN4 Gene mutation, c.1737 + 1 G > T, causes familial bradycardia, reduced heart rate response, impaired chronotropic competence and increased short-term heart rate variability. Int J Cardiol 2017; 241:364-372. [DOI: 10.1016/j.ijcard.2017.04.058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/22/2017] [Accepted: 04/19/2017] [Indexed: 11/26/2022]
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25
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Abstract
The S672R mutation in heart cell ion channels leads to low heart rates and arrhythmia by an unknown route. A multifaceted NMR analysis now demonstrates that this mutant impacts allosteric coupling in domains inside of the cell to change channel activation, providing a mechanistic explanation for phenotypic outcomes.
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Affiliation(s)
- Chung-Jung Tsai
- From the Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland 21702 and
| | - Ruth Nussinov
- From the Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland 21702 and
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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26
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Boulton S, Akimoto M, Akbarizadeh S, Melacini G. Free energy landscape remodeling of the cardiac pacemaker channel explains the molecular basis of familial sinus bradycardia. J Biol Chem 2017; 292:6414-6428. [PMID: 28174302 DOI: 10.1074/jbc.m116.773697] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 01/28/2017] [Indexed: 12/21/2022] Open
Abstract
The hyperpolarization-activated and cyclic nucleotide-modulated ion channel (HCN) drives the pacemaker activity in the heart, and its malfunction can result in heart disorders. One such disorder, familial sinus bradycardia, is caused by the S672R mutation in HCN, whose electrophysiological phenotypes include a negative shift in the channel activation voltage and an accelerated HCN deactivation. The outcomes of these changes are abnormally low resting heart rates. However, the molecular mechanism underlying these electrophysiological changes is currently not fully understood. Crystallographic investigations indicate that the S672R mutation causes limited changes in the structure of the HCN intracellular gating tetramer, but its effects on protein dynamics are unknown. Here, we utilize comparative S672R versus WT NMR analyses to show that the S672R mutation results in extensive perturbations of the dynamics in both apo- and holo-forms of the HCN4 isoform, reflecting how S672R remodels the free energy landscape for the modulation of HCN4 by cAMP, i.e. the primary cyclic nucleotide modulator of HCN channels. We show that the S672R mutation results in a constitutive shift of the dynamic auto-inhibitory equilibrium toward inactive states of HCN4 and broadens the free-energy well of the apo-form, enhancing the millisecond to microsecond dynamics of the holo-form at sites critical for gating cAMP binding. These S672R-induced variations in dynamics provide a molecular basis for the electrophysiological phenotypes of this mutation and demonstrate that the pathogenic effects of the S672R mutation can be rationalized primarily in terms of modulations of protein dynamics.
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Affiliation(s)
- Stephen Boulton
- From the Departments of Biochemistry and Biomedical Sciences and
| | - Madoka Akimoto
- Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Sam Akbarizadeh
- Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Giuseppe Melacini
- From the Departments of Biochemistry and Biomedical Sciences and .,Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
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27
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Sharpe EJ, Larson ED, Proenza C. Cyclic AMP reverses the effects of aging on pacemaker activity and If in sinoatrial node myocytes. J Gen Physiol 2017; 149:237-247. [PMID: 28057842 PMCID: PMC5299620 DOI: 10.1085/jgp.201611674] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/09/2016] [Accepted: 11/22/2016] [Indexed: 12/19/2022] Open
Abstract
Aging reduces pacemaker activity and shifts the voltage dependence of activation of the funny current, If, in sinoatrial node myocytes. Sharpe et al. find that these effects of aging can be reversed by application of exogenous cAMP but not by stimulation of endogenous cAMP. Aerobic capacity decreases with age, in part because of an age-dependent decline in maximum heart rate (mHR) and a reduction in the intrinsic pacemaker activity of the sinoatrial node of the heart. Isolated sinoatrial node myocytes (SAMs) from aged mice have slower spontaneous action potential (AP) firing rates and a hyperpolarizing shift in the voltage dependence of activation of the “funny current,” If. Cyclic AMP (cAMP) is a critical modulator of both AP firing rate and If in SAMs. Here, we test the ability of endogenous and exogenous cAMP to overcome age-dependent changes in acutely isolated murine SAMs. We found that maximal stimulation of endogenous cAMP with 3-isobutyl-1-methylxanthine (IBMX) and forskolin significantly increased AP firing rate and depolarized the voltage dependence of activation of If in SAMs from both young and aged mice. However, these changes were insufficient to overcome the deficits in aged SAMs, and significant age-dependent differences in AP firing rate and If persisted in the presence of IBMX and forskolin. In contrast, the effects of aging on SAMs were completely abolished by a high concentration of exogenous cAMP, which restored AP firing rate and If activation to youthful levels in cells from aged animals. Interestingly, the age-dependent differences in AP firing rates and If were similar in whole-cell and perforated-patch recordings, and the hyperpolarizing shift in If persisted in excised inside-out patches, suggesting a limited role for cAMP in causing these changes. Collectively, the data indicate that aging does not impose an absolute limit on pacemaker activity and that it does not act by simply reducing the concentration of freely diffusible cAMP in SAMs.
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Affiliation(s)
- Emily J Sharpe
- Department of Physiology and Biophysics, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045
| | - Eric D Larson
- Department of Physiology and Biophysics, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045
| | - 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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Biel S, Aquila M, Hertel B, Berthold A, Neumann T, DiFrancesco D, Moroni A, Thiel G, Kauferstein S. Mutation in S6 domain of HCN4 channel in patient with suspected Brugada syndrome modifies channel function. Pflugers Arch 2016; 468:1663-71. [PMID: 27553229 DOI: 10.1007/s00424-016-1870-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 07/21/2016] [Accepted: 08/11/2016] [Indexed: 12/17/2022]
Abstract
Diseases such as the sick sinus and the Brugada syndrome are cardiac abnormalities, which can be caused by a number of genetic aberrances. Among them are mutations in HCN4, a gene, which encodes the hyperpolarization-activated, cyclic nucleotide-gated ion channel 4; this pacemaker channel is responsible for the spontaneous activity of the sinoatrial node. The present genetic screening of patients with suspected or diagnosed Brugada or sick sinus syndrome identified in 1 out of 62 samples the novel mutation V492F. It is located in a highly conserved site of hyperpolarization-activated cyclic nucleotide-gated (HCN)4 channel downstream of the filter at the start of the last transmembrane domain S6. Functional expression of mutant channels in HEK293 cells uncovered a profoundly reduced channel function but no appreciable impact on channel synthesis and trafficking compared to the wild type. The inward rectifying HCN4 current could be partially rescued by an expression of heteromeric channels comprising wt and mutant monomers. These heteromeric channels were responsive to cAMP but they required a more negative voltage for activation and they exhibited a lower current density than the wt channel. This suggests a dominant negative effect of the mutation in patients, which carry this heterozygous mutation. Such a modulation of HCN4 activity could be the cause of the diagnosed cardiac abnormality.
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Affiliation(s)
- Stephanie Biel
- Institute of Legal Medicine, University of Frankfurt, Kennedyallee 104, 60596, Frankfurt am Main, Germany
| | - Marco Aquila
- Department of Biosciences and CNR IBF-Mi, University of Milano, Via Celoria 26, 20133, Milan, Italy
| | - Brigitte Hertel
- Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany
| | - Anne Berthold
- Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany
| | - Thomas Neumann
- Kerckhoff Heart and Thorax Center, University of Giessen, Benekestraße 2, 61231, Bad Nauheim, Germany
| | - Dario DiFrancesco
- The PaceLab, Department of Biosciences, University of Milano, via Celoria 26, 20133, Milan, Italy
| | - Anna Moroni
- Department of Biosciences and CNR IBF-Mi, University of Milano, Via Celoria 26, 20133, Milan, Italy
| | - Gerhard Thiel
- Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany.
| | - Silke Kauferstein
- Institute of Legal Medicine, University of Frankfurt, Kennedyallee 104, 60596, Frankfurt am Main, Germany
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29
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Baruscotti M, Bianco E, Bucchi A, DiFrancesco D. Current understanding of the pathophysiological mechanisms responsible for inappropriate sinus tachycardia: role of the If "funny" current. J Interv Card Electrophysiol 2016; 46:19-28. [PMID: 26781742 DOI: 10.1007/s10840-015-0097-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 12/28/2015] [Indexed: 01/01/2023]
Abstract
BACKGROUND Together with the afferent branches of the autonomic nervous system, the sinoatrial node (SAN) forms a functional unit whose function is to fire rhythmic action potentials at a rate optimal for coping with the metabolic needs of the body. Dysfunctional behavior of this complex unit may thus result in SAN rhythm disorders. Among these disorders, there is the inappropriate sinus tachycardia (IST) which occurs when an unjustified fast SAN rate is present. METHODS We here present a critical review of the role of pacemaker f/HCN channels in cardiac rhythm generation and modulation and their involvement in IST. RESULTS Recent evidence demonstrates that a familial form of IST is associated with a gain-of-function mutation in the HCN4 pacemaker channel (R524Q) which confers an increased sensitivity to the second messenger cAMP, a key mediator in sympathetic modulation. CONCLUSIONS This finding is consistent with the general view that hypersympathetic tone is one of the causes of IST and introduces the novel concept of defective funny channel-dependent tachyarrhythmias.
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Affiliation(s)
- Mirko Baruscotti
- Department of Biosciences, Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, via Celoria 26, 20133, Milano, Italy.
| | - Elisabetta Bianco
- Cardiovascular Department, "Ospedali Riuniti di Trieste", University Hospital, Trieste, Italy
| | - Annalisa Bucchi
- Department of Biosciences, Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, via Celoria 26, 20133, Milano, Italy
| | - Dario DiFrancesco
- Department of Biosciences, Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, via Celoria 26, 20133, Milano, Italy.
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30
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Ravagli E, Bucchi A, Bartolucci C, Paina M, Baruscotti M, DiFrancesco D, Severi S. Cell-specific Dynamic Clamp analysis of the role of funny If current in cardiac pacemaking. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:50-66. [PMID: 26718599 DOI: 10.1016/j.pbiomolbio.2015.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/18/2015] [Accepted: 12/16/2015] [Indexed: 01/01/2023]
Abstract
We used the Dynamic Clamp technique for i) comparative validation of conflicting computational models of the hyperpolarization-activated funny current, If, and ii) quantification of the role of If in mediating autonomic modulation of heart rate. Experimental protocols based on the injection of a real-time recalculated synthetic If current in sinoatrial rabbit cells were developed. Preliminary results of experiments mimicking the autonomic modulation of If demonstrated the need for a customization procedure to compensate for cellular heterogeneity. For this reason, we used a cell-specific approach, scaling the maximal conductance of the injected current based on the cell's spontaneous firing rate. The pacemaking rate, which was significantly reduced after application of Ivabradine, was restored by the injection of synthetic current based on the Severi-DiFrancesco formulation, while the injection of synthetic current based on the Maltsev-Lakatta formulation did not produce any significant variation. A positive virtual shift of the If activation curve, mimicking the Isoprenaline effects, led to a significant increase in pacemaking rate (+17.3 ± 6.7%, p < 0.01), although of lower magnitude than that induced by real Isoprenaline (+45.0 ± 26.1%). Similarly, a negative virtual shift of the activation curve significantly lowered the pacemaking rate (-11.8 ± 1.9%, p < 0.001), as did the application of real Acetylcholine (-20.5 ± 5.1%). The Dynamic Clamp approach, applied to the If study in cardiomyocytes for the first time and rate-adapted to manage intercellular variability, indicated that: i) the quantitative description of the If current in the Severi-DiFrancesco model accurately reproduces the effects of the real current on rabbit sinoatrial cell pacemaking rate and ii) a significant portion (50-60%) of the physiological autonomic rate modulation is due to the shift of the If activation curve.
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Affiliation(s)
- E Ravagli
- Computational Physiopathology Unit, Laboratory of Cellular and Molecular Engineering, D.E.I., University of Bologna, Via Venezia 52, 47521 Cesena, Italy
| | - A Bucchi
- The PaceLab, Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milano, Italy
| | - C Bartolucci
- Computational Physiopathology Unit, Laboratory of Cellular and Molecular Engineering, D.E.I., University of Bologna, Via Venezia 52, 47521 Cesena, Italy
| | - M Paina
- The PaceLab, Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milano, Italy
| | - M Baruscotti
- The PaceLab, Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milano, Italy
| | - D DiFrancesco
- The PaceLab, Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milano, Italy
| | - S Severi
- Computational Physiopathology Unit, Laboratory of Cellular and Molecular Engineering, D.E.I., University of Bologna, Via Venezia 52, 47521 Cesena, Italy.
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31
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Ishikawa T, Tsuji Y, Makita N. Inherited bradyarrhythmia: A diverse genetic background. J Arrhythm 2015; 32:352-358. [PMID: 27761158 PMCID: PMC5063261 DOI: 10.1016/j.joa.2015.09.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/03/2015] [Accepted: 09/16/2015] [Indexed: 12/31/2022] Open
Abstract
Bradyarrhythmia is a common heart rhythm abnormality comprising number of diseases and is associated with decreased heart rate due to the failure of action potential generation and propagation at the sinus node. Permanent pacemaker implantation is often used therapeutically to compensate for decreased heart rate and cardiac output. The vast majority of bradyarrhythmia cases are attributable either to aging or to structural abnormalities of the cardiac conduction system, caused by underlying structural heart disease. However, there is a subset of bradyarrhythmia primarily caused by genetic defects in the absence of aging or underlying structural heart disease. These include several genes that play principal roles in cardiac electrophysiology, heart development, cardioprotection, and the structural integrity of the membrane and sarcomere. Recent advances in the functional analysis of mutations using a heterologous expression system and genetically engineered animal models have provided significant insights into the underlying molecular mechanisms responsible for inherited arrhythmia. In this review, current understandings of the genetic and molecular basis of inherited bradyarrhythmia are presented.
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Affiliation(s)
- Taisuke Ishikawa
- Department of Molecular Physiology, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Yukiomi Tsuji
- Department of Molecular Physiology, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Naomasa Makita
- Department of Molecular Physiology, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
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Huang X, Yang P, Yang Z, Zhang H, Ma A. Age-associated expression of HCN channel isoforms in rat sinoatrial node. Exp Biol Med (Maywood) 2015; 241:331-9. [PMID: 26341471 DOI: 10.1177/1535370215603515] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 08/04/2015] [Indexed: 11/16/2022] Open
Abstract
The expression of hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channel isoforms varies among species, cardiac tissues, developmental stages, and disease generation. However, alterations in the HCN channels during aging remain unclear. We investigated the protein expressions of HCN channel isoforms, HCN1-HCN4, in the sinoatrial nodes (SANs) from young (1-month-old), adult (4-month-old), and aged (30-month-old) rats. We found that HCN2 and HCN4 proteins were present in rat SAN using immunohistochemistry; therefore, we quantitatively analyzed their expression by Western blot. Aim to correlate protein expression and pacemaking function, specific blockade of HCN channels with 3 µmol/L ivabradine prolonged the cycle length in the intact rat heart. During the senescent process, the HCN2 and HCN4 protein levels declined, which was accompanied with a decreased effect of ivabradine on rat SAN automaticity. These results indicated the age-associated expression and relative function of HCN channel isoforms.
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Affiliation(s)
- Xin Huang
- Department of Cardiology, First Affiliated Hospital of Xi'an Jiaotong University Health Science Center, Ion Channel Disease Laboratory, Key Laboratory of Environment and Genes related to Diseases of Education Ministry, Xi'an, Shaanxi 710061, P.R. China
| | - Pei Yang
- Department of Orthopedics, Second Affiliated Hospital of Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710004, P.R. China
| | - Zhao Yang
- Institute of Medical Electronics in Medical School, Key Laboratory of Biomedical Information Engineering, Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Hong Zhang
- School of Electrical Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P.R. China
| | - Aiqun Ma
- Department of Cardiology, First Affiliated Hospital of Xi'an Jiaotong University Health Science Center, Ion Channel Disease Laboratory, Key Laboratory of Environment and Genes related to Diseases of Education Ministry, Xi'an, Shaanxi 710061, P.R. China
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HCN4 mutation as a molecular explanation on patients with bradycardia and non-compaction cardiomyopathy. Eur J Med Genet 2015. [DOI: 10.1016/j.ejmg.2015.06.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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DiFrancesco D. HCN4, Sinus Bradycardia and Atrial Fibrillation. Arrhythm Electrophysiol Rev 2015; 4:9-13. [PMID: 26835093 DOI: 10.15420/aer.2015.4.1.9] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 01/29/2015] [Indexed: 01/01/2023] Open
Abstract
Based on their established role in the generation of spontaneous activity in pacemaker cells and control of cardiac rate, funny/ hyperpolarisation-activated, cyclic nucleotide gated 4 (HCN4) channels are natural candidates in the search for causes of sinus arrhythmias. Investigation of funny current-related inheritable arrhythmias has led to the identification of several mutations of the HCN4 gene associated with bradycardia and/or more complex arrhythmias. More recently, the search has been extended to include auxiliary proteins such as the minK-related peptide 1 (MiRP1) β-subunit. All mutations described so far are loss-of-function and in agreement with the role of funny channels, the predominant type of arrhythmia found is bradycardia. Funny channel-linked arrhythmias, however, also include atrioventricular (AV) block and atrial fibrillation, in agreement with an emerging new concept according to which defective funny channels have a still unexplored role in impairing AV conduction and triggering atrial fibrillation. Also, importantly, recent work shows that HCN4 mutations can be associated with cardiac structural abnormalities. In this short review I briefly address the current knowledge of funny/HCN4 channel mutations and associated sinus and more complex arrhythmias.
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Affiliation(s)
- Dario DiFrancesco
- PaceLab, University of Milan and Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata (CIMMBA), Milan, Italy
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Verkerk AO, Wilders R. Pacemaker activity of the human sinoatrial node: an update on the effects of mutations in HCN4 on the hyperpolarization-activated current. Int J Mol Sci 2015; 16:3071-94. [PMID: 25642760 PMCID: PMC4346881 DOI: 10.3390/ijms16023071] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 01/22/2015] [Indexed: 11/22/2022] Open
Abstract
Since 2003, several loss-of-function mutations in the HCN4 gene, which encodes the HCN4 protein, have been associated with sinus node dysfunction. In human sinoatrial node (SAN), HCN4 is the most abundant of the four isoforms of the HCN family. Tetramers of HCN subunits constitute the ion channels that conduct the hyperpolarization-activated "funny" current (If), which plays an important modulating role in SAN pacemaker activity. Voltage-clamp experiments on HCN4 channels expressed in COS-7, CHO and HEK-293 cells, as well as in Xenopus oocytes have revealed changes in the expression and kinetics of mutant channels, but the extent to which especially the kinetic changes would affect If flowing during a human SAN action potential often remains unresolved. In our contribution to the Topical Collection on Human Single Nucleotide Polymorphisms and Disease Diagnostics, we provide an updated review of the mutation-induced changes in the expression and kinetics of HCN4 channels and provide an overview of their effects on If during the time course of a human SAN action potential, as assessed in simulated action potential clamp experiments. Future research may solve apparent inconsistencies between data from clinical studies and data from in vitro and in silico experiments.
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Affiliation(s)
- Arie O Verkerk
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Ronald Wilders
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
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Liang X, Evans SM, Sun Y. Insights into cardiac conduction system formation provided by HCN4 expression. Trends Cardiovasc Med 2015; 25:1-9. [PMID: 25442735 PMCID: PMC5544420 DOI: 10.1016/j.tcm.2014.08.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Revised: 08/28/2014] [Accepted: 08/28/2014] [Indexed: 11/22/2022]
Abstract
Specialized myocytes of the cardiac conduction system (CCS) are essential to coordinate sequential contraction of cardiac atria and ventricles. Anomalies of the CCS can result in lethal cardiac arrhythmias, including sick sinus syndrome and atrial or ventricular fibrillation. To develop future therapies and regenerative medicine aimed at cardiac arrhythmias, it is important to understand formation and function of distinct components of the CCS. Essential to this understanding is the development of CCS-specific markers. In this review, we briefly summarize available mouse models of CCS markers and focus on those involving the hyperpolarization cation-selective nucleotide-gated cation channel, HCN4, which selectively marks all components of the specialized CCS in adult heart. Recent studies have revealed, however, that HCN4 expression during development is highly dynamic in cardiac precursors. These studies have offered insights into the contributions of the first and second heart field to myocyte and conduction system lineages and suggested the timing of allocation of specific conduction system precursors during development. Altogether, they have highlighted the utility of HCN4 as a cell surface marker for distinct components of the CCS at distinct stages of development, which can be utilized to facilitate purification and characterization of CCS precursors in mouse and human model systems and pave the way for regenerative therapies.
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Affiliation(s)
- Xingqun Liang
- Key Laboratory of Arrhythmia, Ministry of Education, East Hospital, Tongji University School of Medicine, Shanghai, China; Department of Medicine, University of California, San Diego, San Diego, CA
| | - Sylvia M Evans
- Department of Medicine, University of California, San Diego, San Diego, CA; Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, San Diego, CA; Department of Pharmacology, University of California, San Diego, San Diego, CA.
| | - Yunfu Sun
- Key Laboratory of Arrhythmia, Ministry of Education, East Hospital, Tongji University School of Medicine, Shanghai, China.
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Verkerk AO, Wilders R. Pacemaker activity of the human sinoatrial node: effects of HCN4 mutations on the hyperpolarization-activated current. Europace 2014; 16:384-95. [PMID: 24569893 DOI: 10.1093/europace/eut348] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The hyperpolarization-activated 'funny' current, If, plays an important modulating role in the pacemaker activity of the human sinoatrial node (SAN). If is carried by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are tetramers built of four HCN subunits. In human SAN, HCN4 is the most abundant of the four isoforms of the HCN family. Since 2003, several loss-of-function mutations in the HCN4 gene, which encodes the HCN4 protein, or in the KCNE2 gene, which encodes the MiRP1 accessory β-subunit, have been associated with sinus node dysfunction. Voltage-clamp experiments on HCN4 channels expressed in COS-7 cells, Xenopus oocytes, or HEK-293 cells have revealed changes in the expression and kinetics of mutant channels, but the extent to which these changes would affect If flowing during a human SAN action potential is unresolved. Here, we review the changes in expression and kinetics of HCN4 mutant channels and provide an overview of their effects on If during the time course of a human SAN action potential, both under resting conditions and upon adrenergic stimulation. These effects are assessed in simulated action potential clamp experiments, with action potentials recorded from isolated human SAN pacemaker cells as command potential and kinetics of If based on voltage-clamp data from these cells. Results from in vitro and in silico experiments show several inconsistencies with clinical observations, pointing to challenges for future research.
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Affiliation(s)
- Arie O Verkerk
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, PO Box 22700, 1100 DE Amsterdam, The Netherlands
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Scicchitano P, Cortese F, Ricci G, Carbonara S, Moncelli M, Iacoviello M, Cecere A, Gesualdo M, Zito A, Caldarola P, Scrutinio D, Lagioia R, Riccioni G, Ciccone MM. Ivabradine, coronary artery disease, and heart failure: beyond rhythm control. Drug Des Devel Ther 2014; 8:689-700. [PMID: 24940047 PMCID: PMC4051626 DOI: 10.2147/dddt.s60591] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Elevated heart rate could negatively influence cardiovascular risk in the general population. It can induce and promote the atherosclerotic process by means of several mechanisms involving endothelial shear stress and biochemical activities. Furthermore, elevated heart rate can directly increase heart ischemic conditions because of its skill in unbalancing demand/supply of oxygen and decreasing the diastolic period. Thus, many pharmacological treatments have been proposed in order to reduce heart rate and ameliorate the cardiovascular risk profile of individuals, especially those suffering from coronary artery diseases (CAD) and chronic heart failure (CHF). Ivabradine is the first pure heart rate reductive drug approved and currently used in humans, created in order to selectively reduce sinus node function and to overcome the many side effects of similar pharmacological tools (ie, β-blockers or calcium channel antagonists). The aim of our review is to evaluate the role and the safety of this molecule on CAD and CHF therapeutic strategies.
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Affiliation(s)
- Pietro Scicchitano
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
| | - Francesca Cortese
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
| | - Gabriella Ricci
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
| | - Santa Carbonara
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
| | - Michele Moncelli
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
| | - Massimo Iacoviello
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
| | - Annagrazia Cecere
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
| | - Michele Gesualdo
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
| | - Annapaola Zito
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
| | - Pasquale Caldarola
- Section of Cardiovascular Diseases, Policlinic, San Paolo Hospital, Bari, Italy
| | - Domenico Scrutinio
- Section of Cardiovascular Diseases, Fondazione Maugeri, Cassano Murge, Italy
| | - Rocco Lagioia
- Section of Cardiovascular Diseases, Fondazione Maugeri, Cassano Murge, Italy
| | - Graziano Riccioni
- Intensive Cardiology Care Unit, San Camillo de Lellis Hospital, Manfredonia, Foggia, Italy
| | - Marco Matteo Ciccone
- Section of Cardiovascular Diseases, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Bari, Italy
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Macri V, Mahida SN, Zhang ML, Sinner MF, Dolmatova EV, Tucker NR, McLellan M, Shea MA, Milan DJ, Lunetta KL, Benjamin EJ, Ellinor PT. A novel trafficking-defective HCN4 mutation is associated with early-onset atrial fibrillation. Heart Rhythm 2014; 11:1055-1062. [PMID: 24607718 DOI: 10.1016/j.hrthm.2014.03.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Indexed: 01/08/2023]
Abstract
BACKGROUND Atrial fibrillation (AF) is the most common arrhythmia, and a recent genome-wide association study identified the hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) as a novel AF susceptibility locus. HCN4 encodes for the cardiac pacemaker channel, and HCN4 mutations are associated with familial sinus bradycardia and AF. OBJECTIVE The purpose of this study was to determine whether novel variants in the coding region of HCN4 contribute to the susceptibility for AF. METHODS We sequenced the coding region of HCN4 for novel variants from 527 cases with early-onset AF from the Massachusetts General Hospital AF Study and 443 referents from the Framingham Heart Study. We used site-directed mutagenesis, cellular electrophysiology, immunocytochemistry, and confocal microscopy to functionally characterize novel variants. RESULTS We found the frequency of novel coding HCN4 variants was 2-fold greater for individuals with AF (7 variants) compared to the referents (3 variants). We determined that of the 7 novel HCN4 variants in our AF cases, 1 (p.Pro257Ser, located in the amino-terminus adjacent to the first transmembrane spanning domain) did not traffic to cell membrane, whereas the remaining 6 were not functionally different from wild type. In addition, the 3 novel variants in our referents did not alter function compared to wild-type. Coexpression studies showed that the p.Pro257Ser mutant channel failed to colocalize with the wild-type HCN4 channel on the cell membrane. CONCLUSION Our findings are consistent with HCN4 haploinsufficiency as the likely mechanism for early-onset AF in the p.Pro257Ser carrier.
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Affiliation(s)
- Vincenzo Macri
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Saagar N Mahida
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Michael L Zhang
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Moritz F Sinner
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Department of Medicine I, University Hospital Grosshadern, Ludwig-Maximilians University, Munich, Germany.,National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, Framingham, Massachusetts, USA
| | - Elena V Dolmatova
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Nathan R Tucker
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Micheal McLellan
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Marisa A Shea
- Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - David J Milan
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Kathryn L Lunetta
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.,Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, USA.,National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, Framingham, Massachusetts, USA
| | - Emelia J Benjamin
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.,Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, USA.,National Heart, Lung, and Blood Institute's and Boston University's Framingham Heart Study, Framingham, Massachusetts, USA.,Preventive Medicine Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.,Cardiology Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Patrick T Ellinor
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts, USA
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