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Gupta P, Gupta A, Gupta K, Bansal S, Sharma M, Balakrishnan I. Prevalence, Outcomes, and Predictors of Prolonged Corrected QT Interval in Hydroxychloroquine-Naïve Hospitalized COVID-19 Patients. Cardiovasc Toxicol 2024; 24:1053-1066. [PMID: 38954228 DOI: 10.1007/s12012-024-09886-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 06/19/2024] [Indexed: 07/04/2024]
Abstract
The studies regarding prevalence, outcomes, and predictors of prolonged corrected QT (QTc) among COVID-19 patients not on QTc-prolonging medication are not available in the literature. In this retrospective cohort study, the QTc of 295 hospital-admitted COVID-19 patients was analyzed and its association with in-hospital mortality was determined. The QTc was prolonged in 14.6% (43/295) of the study population. Prolonged QTc was seen in patients with older age (P = 0.018), coronary artery disease (P = 0.001), congestive heart failure (P = 0.042), elevated N-terminal-pro-B-type natriuretic peptide (NT-ProBNP) (P < 0.0001), and on remdesivir (P = 0.046). No episode of torsades de pointes arrhythmia or any arrhythmic death was observed among patients with prolonged QTc. The mortality was significantly high in patients with prolonged QTc (P = 0.003). The multivariate logistic regression analysis showed coronary artery disease (odds ratio (OR): 4.153, 95% CI 1.37-14.86; P = 0.013), and NT-ProBNP (ng/L) (OR: 1.000, 95% CI 1.000-1.000; P = 0.007) as predictors of prolonged QTc. The prolonged QTc was associated with the worst in-hospital survival (p by log-rank 0.001). A significant independent association was observed between prolonged QTc and in-hospital mortality in multivariate cox-regression analysis (adjusted hazard ratio: 3.861; (95% CI 1.719-6.523), P < 0.0001). QTc was found to be a marker of underlying comorbidities among COVID-19 patients. Prolonged QTc in hospitalized COVID-19 patients was independently associated with in-hospital mortality.
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Affiliation(s)
- Praveen Gupta
- Department of Cardiology, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, 110029, India.
| | - Anunay Gupta
- Department of Cardiology, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, 110029, India
| | - Kapil Gupta
- Department of Anesthesia and Critical Care, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, 110029, India
| | - Sandeep Bansal
- Department of Cardiology, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, 110029, India
| | - Monica Sharma
- Department of Hematology, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, 110029, India
| | - Ira Balakrishnan
- Department of Anesthesia and Critical Care, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, 110029, India
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2
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Benselama W, Benchouk W. In silico design based on quantum chemical, molecular docking studies and ADMET predictions of ciprofloxacin derivatives as novel potential antibacterial and antimycrobacterium agents. J Biomol Struct Dyn 2024; 42:7650-7666. [PMID: 37551116 DOI: 10.1080/07391102.2023.2240906] [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: 02/23/2023] [Accepted: 07/20/2023] [Indexed: 08/09/2023]
Abstract
Drug designing and development is an important area of research for pharmaceutical companies and chemical scientists. In this paper, we report the prediction of new ciprofloxacin derivatives by quantum chemical, molecular docking studies and pharmacokinetic properties. Theoretical studies were performed by geometry optimization computation using B3LYP level at 6-311 G (d,p) basis set. The absorption, distribution, metabolism, excretion and toxicity (ADMET) parameters were predicted and the result show that all compounds have a great ADMET profile. To study the antibacterial, anti-Mycobacterium tuberculosis activities, ciprofloxacin and its derivatives were interacted with the proteins: Thymidylate Kinase (PDB: 4QGG), Biotin carboxylase (PDB: 3JZF) and β-lactamase BlaC (PDB: 3N7W). The results of the docking studies indicate that one pharmacophore designed presents a great inhibition behavior against gram-positive organism (4QGG) and significant interactions observed between the compound and ARG48, GLN101, ARG105 and GLU37 residues of 4QGG. Also, another derivative designed present the best inhibition against gram-negative organism (3JZF) several interactions were noticed between the compound and GLY165, ILE287, LEU278, HIS236, HIS209, MET169 and LYS159 residues of (3JZF). As well as, one designed candidate is good inhibitors for β-lactamase (3N7W) multiple no bonded interactions were observed between the compound and SER84, ILE117, ASN186, LYS87, ARG187, ASN186 and THR251 residues of(3N7W). Molecular dynamics (MD) simulation study was also performed for 100 ns to confirm the stability behaviour of the main protein and inhibitor complexes. The MD simulation study validated the stability of three compounds in the protein binding pocket as potent binders. Natural bonding orbital analysis, reactivity indices and molecular electrostatic potential were carried out. The research finding of this study can be helpful to design a new potent antibacterial, antimycrobacterium candidate's drugs that will serve as the basis for future in vitro and in vivo research.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Wafa Benselama
- Laboratory of Applied Thermodynamics and Molecular Modeling, Department of Chemistry, Faculty of Science, University of Tlemcen, Tlemcen, Algeria
| | - Wafaa Benchouk
- Laboratory of Applied Thermodynamics and Molecular Modeling, Department of Chemistry, Faculty of Science, University of Tlemcen, Tlemcen, Algeria
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3
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Senthivel V, Jolly B, Vr A, Bajaj A, Bhoyar R, Imran M, Vignesh H, Divakar MK, Sharma G, Rai N, Kumar K, Mp J, Krishna M, Shenthar J, Ali M, Abqari S, Nadri G, Scaria V, Naik N, Sivasubbu S. Whole genome sequencing of families diagnosed with cardiac channelopathies reveals structural variants missed by whole exome sequencing. J Hum Genet 2024; 69:455-465. [PMID: 38890497 DOI: 10.1038/s10038-024-01265-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 03/07/2024] [Accepted: 06/02/2024] [Indexed: 06/20/2024]
Abstract
Cardiac channelopathies are a group of heritable disorders that affect the heart's electrical activity due to genetic variations present in genes coding for ion channels. With the advent of new sequencing technologies, molecular diagnosis of these disorders in patients has paved the way for early identification, therapeutic management and family screening. The objective of this retrospective study was to understand the efficacy of whole-genome sequencing in diagnosing patients with suspected cardiac channelopathies who were reported negative after whole exome sequencing and analysis. We employed a 3-tier analysis approach to identify nonsynonymous variations and loss-of-function variations missed by exome sequencing, and structural variations that are better resolved only by sequencing whole genomes. By performing whole genome sequencing and analyzing 25 exome-negative cardiac channelopathy patients, we identified 3 pathogenic variations. These include a heterozygous likely pathogenic nonsynonymous variation, CACNA1C:NM_000719:exon19:c.C2570G:p. P857R, which causes autosomal dominant long QT syndrome in the absence of Timothy syndrome, a heterozygous loss-of-function variation CASQ2:NM_001232.4:c.420+2T>C classified as pathogenic, and a 9.2 kb structural variation that spans exon 2 of the KCNQ1 gene, which is likely to cause Jervell-Lange-Nielssen syndrome. In addition, we also identified a loss-of-function variation and 16 structural variations of unknown significance (VUS). Further studies are required to elucidate the role of these identified VUS in gene regulation and decipher the underlying genetic and molecular mechanisms of these disorders. Our present study serves as a pilot for understanding the utility of WGS over clinical exomes in diagnosing cardiac channelopathy disorders.
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Affiliation(s)
- Vigneshwar Senthivel
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Bani Jolly
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Arvinden Vr
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Anjali Bajaj
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Rahul Bhoyar
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India
| | - Mohamed Imran
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Harie Vignesh
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India
| | - Mohit Kumar Divakar
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Gautam Sharma
- Department of Cardiology, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Nitin Rai
- Department of Cardiology, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Kapil Kumar
- Department of Cardiology, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Jayakrishnan Mp
- Government Medical College, Kozhikode, Kerala, 673008, India
| | - Maniram Krishna
- Tiny Hearts Fetal and Pediatric Clinic, Thanjavur, Tamil Nadu, 613001, India
| | - Jeyaprakash Shenthar
- Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, 560069, India
| | - Muzaffar Ali
- Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, 560069, India
| | - Shaad Abqari
- Jawaharlal Nehru Medical College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India
| | - Gulnaz Nadri
- Jawaharlal Nehru Medical College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India
| | - Vinod Scaria
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Nitish Naik
- Department of Cardiology, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Sridhar Sivasubbu
- CSIR- Institute of Genomics and Integrative Biology, Mathura Road, Sukhdev Vihar, New Delhi, 110025, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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4
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Song M, Zhuge Y, Tu Y, Liu J, Liu W. The Multifunctional Role of KCNE2: From Cardiac Arrhythmia to Multisystem Disorders. Cells 2024; 13:1409. [PMID: 39272981 PMCID: PMC11393857 DOI: 10.3390/cells13171409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2024] [Revised: 08/17/2024] [Accepted: 08/21/2024] [Indexed: 09/15/2024] Open
Abstract
The KCNE2 protein is encoded by the kcne2 gene and is a member of the KCNE protein family, also known as the MinK-related protein 1 (MiRP1). It is mostly present in the epicardium of the heart and gastric mucosa, and it is also found in the thyroid, pancreatic islets, liver and lung, among other locations, to a lesser extent. It is involved in numerous physiological processes because of its ubiquitous expression and partnering promiscuity, including the modulation of voltage-dependent potassium and calcium channels involved in cardiac action potential repolarization, and regulation of secretory processes in multiple epithelia, such as gastric acid secretion, thyroid hormone synthesis, generation and secretion of cerebrospinal fluid. Mutations in the KCNE2 gene or aberrant expression of the protein may play a critical role in cardiovascular, neurological, metabolic and multisystem disorders. This article provides an overview of the advancements made in understanding the physiological functions in organismal homeostasis and the pathophysiological consequences of KCNE2 in multisystem diseases.
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Affiliation(s)
- Ming Song
- Department of Pathophysiology, Medical School, Shenzhen University, Shenzhen 518060, China
| | - Yixin Zhuge
- Department of Pathophysiology, Medical School, Shenzhen University, Shenzhen 518060, China
| | - Yuqi Tu
- Department of Pathophysiology, Medical School, Shenzhen University, Shenzhen 518060, China
| | - Jie Liu
- Department of Pathophysiology, Medical School, Shenzhen University, Shenzhen 518060, China
| | - Wenjuan Liu
- Department of Pathophysiology, Medical School, Shenzhen University, Shenzhen 518060, China
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5
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Codding SJ, Trudeau MC. Photoinhibition of the hERG potassium channel PAS domain by ultraviolet light speeds channel closing. Biophys J 2024; 123:2392-2405. [PMID: 38796698 PMCID: PMC11365103 DOI: 10.1016/j.bpj.2024.05.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/30/2024] [Accepted: 05/22/2024] [Indexed: 05/28/2024] Open
Abstract
hERG potassium channels are critical for cardiac excitability. hERG channels have a Per-Arnt-Sim (PAS) domain at their N-terminus, and here, we examined the mechanism for PAS domain regulation of channel opening and closing (gating). We used TAG codon suppression to incorporate the noncanonical amino acid 4-benzoyl-L-phenylalanine (BZF), which is capable of forming covalent cross-links after photoactivation by ultraviolet (UV) light, at three locations (G47, F48, and E50) in the PAS domain. We found that hERG-G47BZF channels had faster closing (deactivation) when irradiated in the open state (at 0 mV) but showed no measurable changes when irradiated in the closed state (at -100 mV). hERG-F48BZF channels had slower activation, faster deactivation, and a marked rightward shift in the voltage dependence of activation when irradiated in the open (at 0 mV) or closed (at -100 mV) state. hERG-E50BZF channels had no measurable changes when irradiated in the open state (at 0 mV) but had slower activation, faster deactivation, and a rightward shift in the voltage dependence of activation when irradiated in the closed state (at -100mV), indicating that hERG-E50BZF had a state-dependent difference in UV photoactivation, which we interpret to mean that PAS underwent molecular motions between the open and closed states. Moreover, we propose that UV-dependent biophysical changes in hERG-G47BZF, F48BZF, and E50BZF were the direct result of photochemical cross-linking that reduced dynamic motions in the PAS domain and broadly stabilized the closed state relative to the open state of the channel.
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Affiliation(s)
- Sara J Codding
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Matthew C Trudeau
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland.
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6
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Roston TM, Bezzerides VJ, Roberts JD, Abrams DJ. Management of ultrarare inherited arrhythmia syndromes. Heart Rhythm 2024:S1547-5271(24)03142-4. [PMID: 39154872 DOI: 10.1016/j.hrthm.2024.08.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 08/06/2024] [Accepted: 08/08/2024] [Indexed: 08/20/2024]
Abstract
Ultrarare inherited arrhythmia syndromes are increasingly diagnosed as a result of increased awareness as well as increased availability and reduced cost of genetic testing. Yet by definition, their rarity and heterogeneous expression make development of evidence-based management strategies more challenging, typically employing strategies garnered from similar genetic cardiac disorders. For the most part, reliance on anecdotal experiences, expert opinion, and small retrospective cohort studies is the only means to diagnose and to treat these patients. Here we review the management of specific ultrarare inherited arrhythmic syndromes together with the genetic and molecular basis, which will become increasingly important with the development of targeted therapies to correct the biologic basis of these disorders.
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Affiliation(s)
- Thomas M Roston
- Division of Cardiology and Centre for Cardiovascular Innovation, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Vassilios J Bezzerides
- Center for Cardiovascular Genetics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jason D Roberts
- Population Health Research Institute, McMaster University, and Hamilton Health Sciences, Hamilton, Ontario, Canada
| | - Dominic J Abrams
- Center for Cardiovascular Genetics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts.
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7
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Chang G, Aroge FA, Venkateshappa R, Claydon TW, Sun B. Development of an Absolute Quantification Method for hERG Using PRM with Single Isotopologue in-Sample Calibration. ACS OMEGA 2024; 9:33972-33982. [PMID: 39130540 PMCID: PMC11308013 DOI: 10.1021/acsomega.4c04541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 08/13/2024]
Abstract
The human ether-à-go-go-related gene (KCNH2)-encoded protein hERG constitutes the α subunit of the Kv11.1 channel and contributes to the I kr current, which plays an important role in the cardiac action potential. Genetically and xenobiotically triggered malfunctions of hERG can cause arrhythmia. The expression of hERG in various study systems was assessed mainly as the fold change relative to the corresponding control. Here, we developed a simple and sensitive quantitation method using targeted mass spectrometry, i.e., the parallel reaction monitoring approach, to measure the absolute quantity of hERG in copy number. Such measurements do not require controls, and the obtained values can be compared with similar results for any other protein. To effectively avoid matrix effects, we used the heavy-match-light (HML) in-sample calibration approach that requires only a single isotopologue to achieve copy-number quantitation. No significant difference was observed in the results obtained by HML and by the classic standard addition in-sample calibration approach. Using four proteotypic peptides, we quantified the average number of copies of hERG in the HEK293T heterologous expression system as 3.6 ± 0.5 × 106 copies/cell, i.e., 1 million copies/cell for the fully assembled Kv11.1 channel.
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Affiliation(s)
- Ge Chang
- Department
of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A1S6, Canada
| | - Fabusuyi A. Aroge
- School
of Mechatronic Systems Engineering, Simon
Fraser University, Surrey, British Columbia V3T0A3, Canada
| | - Ravichandra Venkateshappa
- Department
of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A1S6, Canada
| | - Tom W. Claydon
- Department
of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A1S6, Canada
| | - Bingyun Sun
- Department
of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A1S6, Canada
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Davis J, Cornwell JD, Campagna N, Guo J, Li W, Yang T, Wang T, Zhang S. Rescue of expression and function of long QT syndrome-causing mutant hERG channels by enhancing channel stability in the plasma membrane. J Biol Chem 2024; 300:107526. [PMID: 38960041 PMCID: PMC11325228 DOI: 10.1016/j.jbc.2024.107526] [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: 04/23/2024] [Revised: 06/21/2024] [Accepted: 06/23/2024] [Indexed: 07/05/2024] Open
Abstract
The human ether-a-go-go-related gene (hERG) encodes the Kv11.1 (or hERG) channel that conducts the rapidly activating delayed rectifier potassium current (IKr). Naturally occurring mutations in hERG impair the channel function and cause long QT syndrome type 2. Many missense hERG mutations lead to a lack of channel expression on the cell surface, representing a major mechanism for the loss-of-function of mutant channels. While it is generally thought that a trafficking defect underlies the lack of channel expression on the cell surface, in the present study, we demonstrate that the trafficking defective mutant hERG G601S can reach the plasma membrane but is unstable and quickly degrades, which is akin to WT hERG channels under low K+ conditions. We previously showed that serine (S) residue at 624 in the innermost position of the selectivity filter of hERG is involved in hERG membrane stability such that substitution of serine 624 with threonine (S624T) enhances hERG stability and renders hERG insensitive to low K+ culture. Here, we report that the intragenic addition of S624T substitution to trafficking defective hERG mutants G601S, N470D, and P596R led to a complete rescue of the function of these otherwise loss-of-function mutant channels to a level similar to the WT channel, representing the most effective rescue means for the function of mutant hERG channels. These findings not only provide novel insights into hERG mutation-mediated channel dysfunction but also point to the critical role of S624 in hERG stability on the plasma membrane.
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Affiliation(s)
- Jordan Davis
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - James D Cornwell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Noah Campagna
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Jun Guo
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Wentao Li
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Tonghua Yang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Tingzhong Wang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
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9
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Stevens-Sostre WA, Flores-Aldama L, Bustos D, Li J, Morais-Cabral JH, Delemotte L, Robertson GA. An intracellular hydrophobic nexus critical for hERG1 channel slow deactivation. Biophys J 2024; 123:2024-2037. [PMID: 38219015 PMCID: PMC11309987 DOI: 10.1016/j.bpj.2024.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 11/17/2023] [Accepted: 01/09/2024] [Indexed: 01/15/2024] Open
Abstract
Slow deactivation is a critical property of voltage-gated K+ channels encoded by the human Ether-à-go-go-Related Gene 1 (hERG). hERG1 channel deactivation is modulated by interactions between intracellular N-terminal Per-Arnt-Sim (PAS) and C-terminal cyclic nucleotide-binding homology (CNBh) domains. The PAS domain is multipartite, comprising a globular domain (gPAS; residues 26-135) and an N-terminal PAS-cap that is further subdivided into an initial unstructured "tip" (residues 1-12) and an amphipathic α-helical region (residues 13-25). Although the PAS-cap tip has long been considered the effector of slow deactivation, how its position near the gating machinery is controlled has not been elucidated. Here, we show that a triad of hydrophobic interactions among the gPAS, PAS-cap α helix, and the CNBh domains is required to support slow deactivation in hERG1. The primary sequence of this "hydrophobic nexus" is highly conserved among mammalian ERG channels but shows key differences to fast-deactivating Ether-à-go-go 1 (EAG1) channels. Combining sequence analysis, structure-directed mutagenesis, electrophysiology, and molecular dynamics simulations, we demonstrate that polar serine substitutions uncover an intermediate deactivation mode that is also mimicked by deletion of the PAS-cap α helix. Molecular dynamics simulation analyses of the serine-substituted channels show an increase in distance among the residues of the hydrophobic nexus, a rotation of the intracellular gating ring, and a retraction of the PAS-cap tip from its receptor site near the voltage sensor domain and channel gate. These findings provide compelling evidence that the hydrophobic nexus coordinates the respective components of the intracellular gating ring and positions the PAS-cap tip to control hERG1 deactivation gating.
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Affiliation(s)
- Whitney A Stevens-Sostre
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Lisandra Flores-Aldama
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Daniel Bustos
- Centro de Investigación de Estudios Avanzados Del Maule (CIEAM), Vicerrectoría de Investigación y Postgrado, Universidad Católica Del Maule, Talca, Chile; Laboratorio de Bioinformática y Química Computacional (LBQC), Departamento de Medicina Traslacional, Facultad de Medicina, Universidad Católica Del Maule, Talca, Chile
| | - Jin Li
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - João H Morais-Cabral
- Instituto de Investigação e Inovação Em Saude da Universidade Do Porto (i3S); Instituto de Biologia Molecular e Celular, Universidade Do Porto, Porto, Portugal
| | - Lucie Delemotte
- KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden
| | - Gail A Robertson
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
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El Sherbini A, Liblik K, Lee J, Baranchuk A, Zhang S, El-Diasty M. Opioids-induced inhibition of HERG ion channels and sudden cardiac death, a systematic review of current literature. Trends Cardiovasc Med 2024; 34:279-285. [PMID: 37015297 DOI: 10.1016/j.tcm.2023.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/28/2023] [Accepted: 03/28/2023] [Indexed: 04/06/2023]
Abstract
BACKGROUND It is estimated that over 60 million individuals regularly use opioids globally, with opioid use disorder increasing substantially in the past decade. Several reports have linked sudden cardiac death, QTc prolongation, and other adverse cardiovascular outcomes with opioid use through their inhibitory effect on the human ether-a-go-go-related gene (HERG) ion channel. Therefore, understanding this underlying mechanism may be critical for risk prevention and management in prescribing opioids and treating patients with opioid dependency. AIM The present systematic review summarizes the current literature on the impact of opioids-induced inhibition of HERG channel function and its relationship with sudden cardiac death, QTc prolongation, and other cardiovascular adverse effects. METHODS A systematic review was conducted of the databases PubMed, EMBASE, Cochrane, and ClinicalTrials.gov of primary studies that reported the effects of opioids on HERG channel function and associated cardiovascular outcomes. RESULTS The search identified 1,546 studies, of which 12 were finally included for data extraction. Based on the current literature, methadone, oliceridine, l-α-acetylmethadol (LAAM), and fentanyl were found to inhibit the HERG channel function and were associated with QTc prolongation. However, other opioids such as morphine, codeine, tramadol, and buprenorphine were not associated with inhibition of HERG channels or QTc prolongation. Additional cardiac outcomes associated with opioid related HERG channels dysfunction included sudden cardiac death and Torsade de Pointes. CONCLUSION Our findings suggest that certain opioid consumption may result in the inhibition of HERG channels, subsequently prolonging the QTc interval and increasing patient susceptibility to sudden cardiac death.
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Affiliation(s)
- Adham El Sherbini
- Faculty of Health Sciences, Queen's University, Kingston, ON, Canada
| | - Kiera Liblik
- School of Medicine, Queen's University, Kingston, ON, Canada
| | - Junsu Lee
- Faculty of Health Sciences, Queen's University, Kingston, ON, Canada
| | - Adrian Baranchuk
- Division of Cardiology, Department of Medicine, Queen's University, Kingston, ON, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Mohammad El-Diasty
- Division of Cardiac Surgery, Department of Surgery, Queen's University, 76 Stuart St, Kingston, ON K7L2V7, Canada.
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11
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Wang J, Liu Z, Zhang Y, Zhang M, Chen D, Zhang G. A method of identifying the high-risk mutations of sudden cardiac death at KCNQ1 and KCNH2 genes. J Forensic Leg Med 2024; 105:102707. [PMID: 38908219 DOI: 10.1016/j.jflm.2024.102707] [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: 11/10/2023] [Revised: 04/13/2024] [Accepted: 06/13/2024] [Indexed: 06/24/2024]
Abstract
Sudden Cardiac Death (SCD) often shows negative anatomy results after a systemic autopsy and the gene mutations of potassium channel play a key role in the etiology of SCD. We established a feasible system to detect SCD-related mutations and investigated the mutations at KCNQ1 and KCNH2 genes in the Chinese population. We established a mutation detection system combined with multiplex PCR, SNaPshot technique, and capillary electrophoresis. We genotyped 101 putative mutations at KCNQ1 and KCNH2 genes in 60 SCD of negative anatomy and 50 controls using the established assay and compared Odd Ratio (OR). Four coding variants were identified in the KCNQ1 gene: S546S, I145I, P448R, and G643S. The mutations of I145I and S546S did not differ significantly in the SCD compared with controls. 21 SCD individuals (35 %) and 1 control individual (2 %) showed a genotype of C/G at P448R (OR = 17.5, 95 % CI [2.40-127.82]). 24 SCD individuals (40 %) and 1 control individual (2 %) showed a genotype of C/G at G643S (OR = 20.0, 95 % CI [2.75-145.25]). We established a robust assay for rapid screening the putative SCD-related mutations in KCNQ1 and KCNH2 genes. The new assay in our study is easily amenable to the majority of laboratories without the need for new specialized equipment. Our method will meet the increasing requirement of mutation screening for SCD in regular DNA laboratories and will help screen mutations in those dead of SCD and their relatives.
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Affiliation(s)
- Jiaqi Wang
- School of Forensic Medicine, Shanxi Medical University, Shanxi, 030619, PR China
| | - Zidong Liu
- School of Forensic Medicine, Shanxi Medical University, Shanxi, 030619, PR China
| | - Yuxin Zhang
- School of Forensic Medicine, Shanxi Medical University, Shanxi, 030619, PR China
| | - Mingming Zhang
- School of Forensic Medicine, Shanxi Medical University, Shanxi, 030619, PR China
| | - Deqing Chen
- Department of Pathology, Forensic and Pathology Laboratory, Judicial Expertise Center, Jiaxing University Medical College, Jiaxing, Zhejiang, 314001, PR China.
| | - Gengqian Zhang
- School of Forensic Medicine, Shanxi Medical University, Shanxi, 030619, PR China.
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12
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Gariballa N, Mohamed F, Badawi S, Ali BR. The double whammy of ER-retention and dominant-negative effects in numerous autosomal dominant diseases: significance in disease mechanisms and therapy. J Biomed Sci 2024; 31:64. [PMID: 38937821 PMCID: PMC11210014 DOI: 10.1186/s12929-024-01054-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024] Open
Abstract
The endoplasmic reticulum (ER) employs stringent quality control mechanisms to ensure the integrity of protein folding, allowing only properly folded, processed and assembled proteins to exit the ER and reach their functional destinations. Mutant proteins unable to attain their correct tertiary conformation or form complexes with their partners are retained in the ER and subsequently degraded through ER-associated protein degradation (ERAD) and associated mechanisms. ER retention contributes to a spectrum of monogenic diseases with diverse modes of inheritance and molecular mechanisms. In autosomal dominant diseases, when mutant proteins get retained in the ER, they can interact with their wild-type counterparts. This interaction may lead to the formation of mixed dimers or aberrant complexes, disrupting their normal trafficking and function in a dominant-negative manner. The combination of ER retention and dominant-negative effects has been frequently documented to cause a significant loss of functional proteins, thereby exacerbating disease severity. This review aims to examine existing literature and provide insights into the impact of dominant-negative effects exerted by mutant proteins retained in the ER in a range of autosomal dominant diseases including skeletal and connective tissue disorders, vascular disorders, neurological disorders, eye disorders and serpinopathies. Most crucially, we aim to emphasize the importance of this area of research, offering substantial potential for understanding the factors influencing phenotypic variability associated with genetic variants. Furthermore, we highlight current and prospective therapeutic approaches targeted at ameliorating the effects of mutations exhibiting dominant-negative effects. These approaches encompass experimental studies exploring treatments and their translation into clinical practice.
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Affiliation(s)
- Nesrin Gariballa
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box: 15551, Al-Ain, United Arab Emirates
| | - Feda Mohamed
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box: 15551, Al-Ain, United Arab Emirates
- ASPIRE Precision Medicine Research Institute Abu Dhabi, United Arab Emirates University, Abu Dhabi, United Arab Emirates
| | - Sally Badawi
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box: 15551, Al-Ain, United Arab Emirates
| | - Bassam R Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box: 15551, Al-Ain, United Arab Emirates.
- ASPIRE Precision Medicine Research Institute Abu Dhabi, United Arab Emirates University, Abu Dhabi, United Arab Emirates.
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13
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Wada Y, Wang L, Hall LD, Yang T, Short LL, Solus JF, Glazer AM, Roden DM. The electrophysiologic effects of KCNQ1 extend beyond expression of IKs: evidence from genetic and pharmacologic block. Cardiovasc Res 2024; 120:735-744. [PMID: 38442735 PMCID: PMC11135641 DOI: 10.1093/cvr/cvae042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 01/22/2024] [Accepted: 02/01/2024] [Indexed: 03/07/2024] Open
Abstract
AIMS While variants in KCNQ1 are the commonest cause of the congenital long QT syndrome, we and others find only a small IKs in cardiomyocytes from human-induced pluripotent stem cells (iPSC-CMs) or human ventricular myocytes. METHODS AND RESULTS We studied population control iPSC-CMs and iPSC-CMs from a patient with Jervell and Lange-Nielsen (JLN) syndrome due to compound heterozygous loss-of-function (LOF) KCNQ1 variants. We compared the effects of pharmacologic IKs block to those of genetic KCNQ1 ablation, using JLN cells, cells homozygous for the KCNQ1 LOF allele G643S, or siRNAs reducing KCNQ1 expression. We also studied the effects of two blockers of IKr, the other major cardiac repolarizing current, in the setting of pharmacologic or genetic ablation of KCNQ1: moxifloxacin, associated with a very low risk of drug-induced long QT, and dofetilide, a high-risk drug. In control cells, a small IKs was readily recorded but the pharmacologic IKs block produced no change in action potential duration at 90% repolarization (APD90). In contrast, in cells with genetic ablation of KCNQ1 (JLN), baseline APD90 was markedly prolonged compared with control cells (469 ± 20 vs. 310 ± 16 ms). JLN cells displayed increased sensitivity to acute IKr block: the concentration (μM) of moxifloxacin required to prolong APD90 100 msec was 237.4 [median, interquartile range (IQR) 100.6-391.6, n = 7] in population cells vs. 23.7 (17.3-28.7, n = 11) in JLN cells. In control cells, chronic moxifloxacin exposure (300 μM) mildly prolonged APD90 (10%) and increased IKs, while chronic exposure to dofetilide (5 nM) produced greater prolongation (67%) and no increase in IKs. However, in the siRNA-treated cells, moxifloxacin did not increase IKs and markedly prolonged APD90. CONCLUSION Our data strongly suggest that KCNQ1 expression modulates baseline cardiac repolarization, and the response to IKr block, through mechanisms beyond simply generating IKs.
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Affiliation(s)
- Yuko Wada
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Lili Wang
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Lynn D Hall
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Tao Yang
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Laura L Short
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Joseph F Solus
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Andrew M Glazer
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Dan M Roden
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
- Departments of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
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14
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Timothy KW, Bauer R, Larkin KA, Walsh EP, Abrams DJ, Corcia CG, Valsamakis A, Pitt GS, Dick IE, Golden A. A Natural History Study of Timothy Syndrome. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.20.24307583. [PMID: 38826393 PMCID: PMC11142284 DOI: 10.1101/2024.05.20.24307583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Timothy syndrome (OMIM #601005) is a rare disease caused by variants in the gene CACNA1C . Timothy syndrome patients were first identified as having a cardiac presentation of Long QT and syndactyly of the fingers and/or toes, and an identical variant in CACNA1C , Gly406Arg. However, since this original identification, more individuals harboring diverse variants in CACNA1C have been identified and have presented with various cardiac and extra-cardiac symptoms. Furthermore, it has remained underexplored whether individuals harboring canonical Gly406Arg variants in mutually exclusive exon 8A (Timothy syndrome 1) or exon 8 (Timothy syndrome 2) have additional symptoms. Here, we describe the first Natural History Study for Timothy syndrome, providing a thorough resource describing the current understanding of disease manifestation in Timothy syndrome patients. Parents of Timothy syndrome children were queried regarding a wide-ranging set of symptoms and features via a survey. Importantly, we find that in addition to cardiac concerns, Timothy syndrome patients commonly share extra-cardiac features including neurodevelopmental impairments, hypoglycemia, and respiratory problems. Our work expands the current understanding of the disorder to better inform the care of Timothy syndrome patients.
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15
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Osorio LA, Lozano M, Soto P, Moreno-Hidalgo V, Arévalo-Gil A, Ramírez-Balaguera A, Hevia D, Cifuentes J, Hidalgo Y, Alcayaga-Miranda F, Pasten C, Morales D, Varela D, Urquidi C, Iturriaga A, Rivera-Palma A, Larrea-Gómez R, Irarrázabal CE. Levels of Small Extracellular Vesicles Containing hERG-1 and Hsp47 as Potential Biomarkers for Cardiovascular Diseases. Int J Mol Sci 2024; 25:4913. [PMID: 38732154 PMCID: PMC11084293 DOI: 10.3390/ijms25094913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/03/2024] [Accepted: 04/07/2024] [Indexed: 05/13/2024] Open
Abstract
The diagnosis of cardiovascular disease (CVD) is still limited. Therefore, this study demonstrates the presence of human ether-a-go-go-related gene 1 (hERG1) and heat shock protein 47 (Hsp47) on the surface of small extracellular vesicles (sEVs) in human peripheral blood and their association with CVD. In this research, 20 individuals with heart failure and 26 participants subjected to cardiac stress tests were enrolled. The associations between hERG1 and/or Hsp47 in sEVs and CVD were established using Western blot, flow cytometry, electron microscopy, ELISA, and nanoparticle tracking analysis. The results show that hERG1 and Hsp47 were present in sEV membranes, extravesicularly exposing the sequences 430AFLLKETEEGPPATE445 for hERG1 and 169ALQSINEWAAQTT- DGKLPEVTKDVERTD196 for Hsp47. In addition, upon exposure to hypoxia, rat primary cardiomyocytes released sEVs into the media, and human cardiomyocytes in culture also released sEVs containing hERG1 (EV-hERG1) and/or Hsp47 (EV-Hsp47). Moreover, the levels of sEVs increased in the blood when cardiac ischemia was induced during the stress test, as well as the concentrations of EV-hERG1 and EV-Hsp47. Additionally, the plasma levels of EV-hERG1 and EV-Hsp47 decreased in patients with decompensated heart failure (DHF). Our data provide the first evidence that hERG1 and Hsp47 are present in the membranes of sEVs derived from the human cardiomyocyte cell line, and also in those isolated from human peripheral blood. Total sEVs, EV-hERG1, and EV-Hsp47 may be explored as biomarkers for heart diseases such as heart failure and cardiac ischemia.
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Affiliation(s)
- Luis A. Osorio
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
| | - Mauricio Lozano
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
| | - Paola Soto
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
| | - Viviana Moreno-Hidalgo
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
| | - Angely Arévalo-Gil
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
| | - Angie Ramírez-Balaguera
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
| | - Daniel Hevia
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
| | - Jorge Cifuentes
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
| | - Yessia Hidalgo
- Laboratory of Nano-Regenerative Medicine, Center of Interventional Medicine for Precision and Advanced Cellular Therapy (IMPACT), Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile
| | - Francisca Alcayaga-Miranda
- Laboratory of Nano-Regenerative Medicine, Center of Interventional Medicine for Precision and Advanced Cellular Therapy (IMPACT), Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile
| | - Consuelo Pasten
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
- Faculty of Medicine, Universidad de los Andes, Santiago 7620001, Chile
| | - Danna Morales
- Faculty of Medicine, Universidad de Chile, Santiago 8380453, Chile
| | - Diego Varela
- Faculty of Medicine, Universidad de Chile, Santiago 8380453, Chile
| | - Cinthya Urquidi
- Department of Epidemiology and Health Studies, Facultad de Medicina, Universidad de los Andes, Santiago 7620001, Chile
| | - Andrés Iturriaga
- Departamento de Matemática y Ciencia de la Computación, Facultad de Ciencia, Universidad de Santiago de Chile, Santiago 9170020, Chile
| | | | | | - Carlos E. Irarrázabal
- Laboratory of Molecular and Integrative Physiology, Physiology Program, Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Santiago 7620001, Chile; (L.A.O.); (C.P.)
- Faculty of Medicine, Universidad de los Andes, Santiago 7620001, Chile
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16
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Mehta A, Chandiramani R, Ghosh B, Asatryan B, Hajra A, Barth AS. Catheter Ablation for Channelopathies: When Is Less More? J Clin Med 2024; 13:2384. [PMID: 38673656 PMCID: PMC11051330 DOI: 10.3390/jcm13082384] [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: 03/05/2024] [Revised: 04/05/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
Ventricular fibrillation (VF) is a common cause of sudden cardiac death in patients with channelopathies, particularly in the young population. Although pharmacological treatment, cardiac sympathectomy, and implantable cardioverter defibrillators (ICD) have been the mainstay in the management of VF in patients with channelopathies, they are associated with significant adverse effects and complications, leading to poor quality of life. Given these drawbacks, catheter ablation has been proposed as a therapeutic option for patients with channelopathies. Advances in imaging techniques and modern mapping technologies have enabled increased precision in identifying arrhythmia triggers and substrate modification. This has aided our understanding of the underlying pathophysiology of ventricular arrhythmias in channelopathies, highlighting the roles of the Purkinje network and the epicardial right ventricular outflow tract in arrhythmogenesis. This review explores the role of catheter ablation in managing the most common channelopathies (Brugada syndrome, congenital long QT syndrome, short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia). While the initial results for ablation in Brugada syndrome are promising, the long-term efficacy and durability of ablation in different channelopathies require further investigation. Given the genetic and phenotypic heterogeneity of channelopathies, future studies are needed to show whether catheter ablation in patients with channelopathies is associated with a reduction in VF, and psychological distress stemming from recurrent ICD shocks, particularly relative to other available therapeutic options (e.g., quinidine in high-risk Brugada patients).
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Affiliation(s)
- Adhya Mehta
- Department of Internal Medicine, Albert Einstein College of Medicine/Jacobi Medical Center, Bronx, NY 10461, USA
| | - Rishi Chandiramani
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Binita Ghosh
- Department of Internal Medicine, SSM Health St. Mary Hospital, St. Louis, MO 63117, USA;
| | - Babken Asatryan
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Adrija Hajra
- Department of Internal Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Andreas S. Barth
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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17
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Lei CL, Whittaker DG, Mirams GR. The impact of uncertainty in hERG binding mechanism on in silico predictions of drug-induced proarrhythmic risk. Br J Pharmacol 2024; 181:987-1004. [PMID: 37740435 DOI: 10.1111/bph.16250] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 08/23/2023] [Accepted: 08/28/2023] [Indexed: 09/24/2023] Open
Abstract
BACKGROUND AND PURPOSE Drug-induced reduction of the rapid delayed rectifier potassium current carried by the human Ether-à-go-go-Related Gene (hERG) channel is associated with increased risk of arrhythmias. Recent updates to drug safety regulatory guidelines attempt to capture each drug's hERG binding mechanism by combining in vitro assays with in silico simulations. In this study, we investigate the impact on in silico proarrhythmic risk predictions due to uncertainty in the hERG binding mechanism and physiological hERG current model. EXPERIMENTAL APPROACH Possible pharmacological binding models were designed for the hERG channel to account for known and postulated small molecule binding mechanisms. After selecting a subset of plausible binding models for each compound through calibration to available voltage-clamp electrophysiology data, we assessed their effects, and the effects of different physiological models, on proarrhythmic risk predictions. KEY RESULTS For some compounds, multiple binding mechanisms can explain the same data produced under the safety testing guidelines, which results in different inferred binding rates. This can result in substantial uncertainty in the predicted torsade risk, which often spans more than one risk category. By comparison, we found that the effect of a different hERG physiological current model on risk classification was subtle. CONCLUSION AND IMPLICATIONS The approach developed in this study assesses the impact of uncertainty in hERG binding mechanisms on predictions of drug-induced proarrhythmic risk. For some compounds, these results imply the need for additional binding data to decrease uncertainty in safety-critical applications.
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Affiliation(s)
- Chon Lok Lei
- Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, China
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Macau, Macau, China
| | - Dominic G Whittaker
- Centre for Mathematical Medicine & Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, UK
| | - Gary R Mirams
- Centre for Mathematical Medicine & Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, UK
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18
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Aguado-Sierra J, Dominguez-Gomez P, Amar A, Butakoff C, Leitner M, Schaper S, Kriegl JM, Darpo B, Vazquez M, Rast G. Virtual clinical QT exposure-response studies - A translational computational approach. J Pharmacol Toxicol Methods 2024; 126:107498. [PMID: 38432528 DOI: 10.1016/j.vascn.2024.107498] [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: 05/30/2023] [Revised: 12/13/2023] [Accepted: 02/29/2024] [Indexed: 03/05/2024]
Abstract
BACKGROUND AND PURPOSE A recent paradigm shift in proarrhythmic risk assessment suggests that the integration of clinical, non-clinical, and computational evidence can be used to reach a comprehensive understanding of the proarrhythmic potential of drug candidates. While current computational methodologies focus on predicting the incidence of proarrhythmic events after drug administration, the objective of this study is to predict concentration-response relationships of QTc as a clinical endpoint. EXPERIMENTAL APPROACH Full heart computational models reproducing human cardiac populations were created to predict the concentration-response relationship of changes in the QT interval as recommended for clinical trials. The concentration-response relationship of the QT-interval prolongation obtained from the computational cardiac population was compared against the relationship from clinical trial data for a set of well-characterized compounds: moxifloxacin, dofetilide, verapamil, and ondansetron. KEY RESULTS Computationally derived concentration-response relationships of QT interval changes for three of the four drugs had slopes within the confidence interval of clinical trials (dofetilide, moxifloxacin and verapamil) when compared to placebo-corrected concentration-ΔQT and concentration-ΔQT regressions. Moxifloxacin showed a higher intercept, outside the confidence interval of the clinical data, demonstrating that in this example, the standard linear regression does not appropriately capture the concentration-response results at very low concentrations. The concentrations corresponding to a mean QTc prolongation of 10 ms were consistently lower in the computational model than in clinical data. The critical concentration varied within an approximate ratio of 0.5 (moxifloxacin and ondansetron) and 1 times (dofetilide, verapamil) the critical concentration observed in human clinical trials. Notably, no other in silico methodology can approximate the human critical concentration values for a QT interval prolongation of 10 ms. CONCLUSION AND IMPLICATIONS Computational concentration-response modelling of a virtual population of high-resolution, 3-dimensional cardiac models can provide comparable information to clinical data and could be used to complement pre-clinical and clinical safety packages. It provides access to an unlimited exposure range to support trial design and can improve the understanding of pre-clinical-clinical translation.
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Affiliation(s)
- Jazmin Aguado-Sierra
- Elem Biotech, Barcelona, Spain; Barcelona Supercomputing Center, Barcelona, Spain.
| | | | | | | | - Michael Leitner
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH and Co. KG, Biberach, Germany.
| | - Stefan Schaper
- Global Computational Biology and Digital Sciences, Boehringer Ingelheim Pharma GmbH and Co. KG, Biberach, Germany.
| | - Jan M Kriegl
- Global Computational Biology and Digital Sciences, Boehringer Ingelheim Pharma GmbH and Co. KG, Biberach, Germany.
| | | | - Mariano Vazquez
- Elem Biotech, Barcelona, Spain; Barcelona Supercomputing Center, Barcelona, Spain.
| | - Georg Rast
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH and Co. KG, Biberach, Germany.
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19
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Codding SJ, Trudeau MC. Photo-crosslinking hERG channels causes a U.V.-driven, state-dependent disruption of kinetics and voltage dependence of activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.09.574834. [PMID: 38260338 PMCID: PMC10802430 DOI: 10.1101/2024.01.09.574834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Human ether-à-go-go related gene (hERG) voltage-activated potassium channels are critical for cardiac excitability. Characteristic slow closing (deactivation) in hERG is regulated by direct interaction between the N-terminal Per-Arnt-Sim (PAS) domain and the C-terminal cyclic nucleotide binding homology domain (CNBHD). We aim to understand how the PAS domain that is distal to the pore rearranges during gating to allosterically regulate the channel pore (and ion flux). To achieve this, we utilized the non-canonical amino acid 4-Benzoyl-L-phenylalanine (BZF) which is a photo-activatable cross-linkable probe, that when irradiated with ultraviolet (U.V.) light forms a double radical capable of forming covalent cross-links with C-H bond-containing groups, enabling selective and potent U.V.-driven photoinactivation of ion channel dynamics. Here we incorporate BZF directly into the hERG potassium channel PAS domain at three locations (G47, F48, and E50) using TAG codon suppression technology. hERG channels with BZF incorporated into the PAS domain (hERG-BZF) showed a significant change in the biophysical properties of the channel. hERG-G47BZF activated slowly when irradiated in the closed state (-100mV) but deactivated quickly when irradiated in both the open (0mV) and closed state. hERG-F48BZF channels showed a state independent and U.V. dose-dependent change in channel activation (slowing down) and channel deactivation (speeding up), as well as a marked change (right-shift) in the voltage-dependence of conductance. When irradiated at -100 mV hERG-E50BZF showed a state dependent and U.V. dose-dependent change in a channel activation (slowing down) and deactivation (speeding up) of channel deactivation, as well as a marked change (right-shift) in the voltage-dependence of conductance that occurred only when the channel was irradiated in the closed state (-100mV). This approach demonstrated that direct photo-crosslinking of the PAS domain in hERG channels causes a measurable change in biophysical parameters and more broadly stabilized the closed state of the channel. We propose that altered channel gating is as a direct result of reduced dynamic motions in the PAS domain of hERG due to photo-chemical crosslinking.
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Affiliation(s)
- Sara J Codding
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Matthew C Trudeau
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
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20
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Genge CE, Muralidharan P, Kemp J, Hull CM, Yip M, Simpson K, Hunter DV, Claydon TW. Zebrafish cardiac repolarization does not functionally depend on the expression of the hERG1b-like transcript. Pflugers Arch 2024; 476:87-99. [PMID: 37934265 DOI: 10.1007/s00424-023-02875-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 10/25/2023] [Accepted: 10/27/2023] [Indexed: 11/08/2023]
Abstract
Zebrafish provide a translational model of human cardiac function. Their similar cardiac electrophysiology enables screening of human cardiac repolarization disorders, drug arrhythmogenicity, and novel antiarrhythmic therapeutics. However, while zebrafish cardiac repolarization is driven by delayed rectifier potassium channel current (IKr), the relative role of alternate channel transcripts is uncertain. While human ether-a-go-go-related-gene-1a (hERG1a) is the dominant transcript in humans, expression of the functionally distinct alternate transcript, hERG1b, modifies the electrophysiological and pharmacologic IKr phenotype. Studies of zebrafish IKr are frequently translated without consideration for the presence and impact of hERG1b in humans. Here, we performed phylogenetic analyses of all available KCNH genes from Actinopterygii (ray-finned fishes). Our findings confirmed zebrafish cardiac zkcnh6a as the paralog of human hERG1a (hKCNH2a), but also revealed evidence of a hERG1b (hKCNH2b)-like N-terminally truncated gene, zkcnh6b, in zebrafish. zkcnh6b is a teleost-specific variant that resulted from the 3R genome duplication. qRT-PCR showed dominant expression of zkcnh6a in zebrafish atrial and ventricular tissue, with low levels of zkcnh6b. Functional evaluation of zkcnh6b in a heterologous system showed no discernable function under the conditions tested, and no influence on zkcnh6a function during the zebrafish ventricular action potential. Our findings provide the first descriptions of the zkcnh6b gene, and show that, unlike in humans, zebrafish cardiac repolarization does not rely upon co-assembly of zERG1a/zERG1b. Given that hERG1b modifies IKr function and drug binding in humans, our findings highlight the need for consideration when translating hERG variant effects and toxicological screens in zebrafish, which lack a functional hERG1b-equivalent gene.
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Affiliation(s)
- Christine E Genge
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Burnaby, B.C, Canada
| | - Padmapriya Muralidharan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Burnaby, B.C, Canada
| | - Jake Kemp
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Burnaby, B.C, Canada
| | - Christina M Hull
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Burnaby, B.C, Canada
| | - Mandy Yip
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Burnaby, B.C, Canada
| | - Kyle Simpson
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Burnaby, B.C, Canada
| | - Diana V Hunter
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Burnaby, B.C, Canada
| | - Thomas W Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Burnaby, B.C, Canada.
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21
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Blomquist VG, Niu J, Choudhury P, Al Saneh A, Colecraft HM, Ahern CA. Transfer RNA-mediated restoration of potassium current and electrical correction in premature termination long-QT syndrome hERG mutants. MOLECULAR THERAPY. NUCLEIC ACIDS 2023; 34:102032. [PMID: 37842167 PMCID: PMC10568093 DOI: 10.1016/j.omtn.2023.102032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 09/14/2023] [Indexed: 10/17/2023]
Abstract
Disease-causing premature termination codons (PTCs) individually disrupt the functional expression of hundreds of genes and represent a pernicious clinical challenge. In the heart, loss-of-function mutations in the hERG potassium channel account for approximately 30% of long-QT syndrome arrhythmia, a lethal cardiac disorder with limited treatment options. Premature termination of ribosomal translation produces a truncated and, for potassium channels, a potentially dominant-negative protein that impairs the functional assembly of the wild-type homotetrameric hERG channel complex. We used high-throughput flow cytometry and patch-clamp electrophysiology to assess the trafficking and voltage-dependent activity of hERG channels carrying patient PTC variants that have been corrected by anticodon engineered tRNA. Adenoviral-mediated expression of mutant hERG channels in cultured adult guinea pig cardiomyocytes prolonged action potential durations, and this deleterious effect was corrected upon adenoviral delivery of a human ArgUGA tRNA to restore full-length hERG protein. The results demonstrate mutation-specific, context-agnostic PTC correction and elevate the therapeutic potential of this approach for rare genetic diseases caused by stop codons.
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Affiliation(s)
- Viggo G. Blomquist
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
| | - Jacqueline Niu
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
| | - Papiya Choudhury
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
| | - Ahmad Al Saneh
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Henry M. Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
| | - Christopher A. Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
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22
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Hu W, Zhang W, Zhang K, Al-Moubarak E, Zhang Y, Harmer SC, Hancox JC, Zhang H. Evaluating pro-arrhythmogenic effects of the T634S-hERG mutation: insights from a simulation study. Interface Focus 2023; 13:20230035. [PMID: 38106919 PMCID: PMC10722218 DOI: 10.1098/rsfs.2023.0035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 11/06/2023] [Indexed: 12/19/2023] Open
Abstract
A mutation to serine of a conserved threonine (T634S) in the hERG K+ channel S6 pore region has been identified as a variant of uncertain significance, showing a loss-of-function effect. However, its potential consequences for ventricular excitation and arrhythmogenesis have not been reported. This study evaluated possible functional effects of the T634S-hERG mutation on ventricular excitation and arrhythmogenesis by using multi-scale computer models of the human ventricle. A Markov chain model of the rapid delayed rectifier potassium current (IKr) was reconstructed for wild-type and T634S-hERG mutant conditions and incorporated into the ten Tusscher et al. models of human ventricles at cell and tissue (1D, 2D and 3D) levels. Possible functional impacts of the T634S-hERG mutation were evaluated by its effects on action potential durations (APDs) and their rate-dependence (APDr) at the cell level; and on the QT interval of pseudo-ECGs, tissue vulnerability to unidirectional conduction block (VW), spiral wave dynamics and repolarization dispersion at the tissue level. It was found that the T634S-hERG mutation prolonged cellular APDs, steepened APDr, prolonged the QT interval, increased VW, destablized re-entry and augmented repolarization dispersion across the ventricle. Collectively, these results imply potential pro-arrhythmic effects of the T634S-hERG mutation, consistent with LQT2.
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Affiliation(s)
- Wei Hu
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
| | - Wenfeng Zhang
- College of Computer and Information Science, Chongqing Normal University, Chongqing, People's Republic of China
| | - Kevin Zhang
- Southmead Hospital, North Bristol Trust, Bristol, UK
| | - Ehab Al-Moubarak
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Yihong Zhang
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Stephen C. Harmer
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Jules C. Hancox
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Henggui Zhang
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, People's Republic of China
- Beijing Academy of Artificial Intelligence, Beijing 100084, People's Republic of China
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23
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Papaioannou P, Wallace MJ, Malhotra N, Mohler PJ, El Refaey M. Biochemical Structure and Function of TRAPP Complexes in the Cardiac System. JACC Basic Transl Sci 2023; 8:1599-1612. [PMID: 38205348 PMCID: PMC10774597 DOI: 10.1016/j.jacbts.2023.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 03/14/2023] [Indexed: 01/12/2024]
Abstract
Trafficking protein particle (TRAPP) is well reported to play a role in the trafficking of protein products within the Golgi and endoplasmic reticulum. Dysfunction in TRAPP has been associated with disorders in the nervous and cardiovascular systems, but the majority of literature focuses on TRAPP function in the nervous system solely. Here, we highlight the known pathways of TRAPP and hypothesize potential impacts of TRAPP dysfunction on the cardiovascular system, particularly the role of TRAPP as a guanine-nucleotide exchange factor for Rab1 and Rab11. We also review the various cardiovascular phenotypes associated with changes in TRAPP complexes and their subunits.
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Affiliation(s)
- Peter Papaioannou
- Frick Center for Heart Failure and Arrhythmia Research, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Division of Cardiac Surgery, Department of Surgery, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Michael J. Wallace
- Frick Center for Heart Failure and Arrhythmia Research, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Nipun Malhotra
- Frick Center for Heart Failure and Arrhythmia Research, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Division of Cardiac Surgery, Department of Surgery, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Peter J. Mohler
- Frick Center for Heart Failure and Arrhythmia Research, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Division of Cardiovascular Medicine, Department of Internal Medicine, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Mona El Refaey
- Frick Center for Heart Failure and Arrhythmia Research, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
- Division of Cardiac Surgery, Department of Surgery, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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24
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Chen B, Tan L, Chen D, Wang X, Liu J, Huang X, Wang Y, Huang S, Mao F, Lian J. KCNH2A561V Heterozygous Mutation Inhibits KCNH2 Protein Expression via The Activation of UPR Mediated by ATF6. Physiol Res 2023; 72:621-631. [PMID: 38015761 PMCID: PMC10751050 DOI: 10.33549/physiolres.935095] [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: 03/12/2023] [Accepted: 05/26/2023] [Indexed: 01/05/2024] Open
Abstract
The potassium channel protein KCNH2 is encoded by KCNH2 gene, and there are more than 300 mutations of KCNH2. Unfolded protein response (UPR) is typically initiated in response to an accumulation of unfolded and/or misfolded proteins in the endoplasmic reticulum (ER). The present study aimed to explore the UPR process and the role of activating transcription factor 6 (ATF6) in the abnormal expression of potassium voltage-gated channel subfamily H member 2 (KCNH2)A561V. The wild-type (wt) KCNH2 and A561V mutant KCNH2 was constructed with his-tag. The 293 cells were used and divided into KCNH2wt+KCNH2A561V, KCNH2wt and KCNH2A561V groups. The expression levels of ATF6 and KCNH2 in different groups were detected by Western blotting, reverse transcription-quantitative PCR, immunofluorescence and immuno-coprecipitation assays. The protein types and abundance of immuno-coprecipitation samples were analyzed by mass spectrometry. The proteomic analysis of the mass spectrometry results was carried out by using the reactome database and GO (Gene Ontology) tool. The mRNA expression levels of KCNH2 and ATF6 in the KCNH2wt+KCNH2A561V group were higher compared with the KCNH2A561V group. However, the full-length protein expression of ATF6 was inhibited, indicating that ATF6 was highly activated and a substantial number of ATF6 was sheared in KCNH2wt+KCNH2A561V group compared with control group. Furthermore, A561V-KCNH2 mutation leading to the accumulation of the immature form of KCNH2 (135 kDa bands) in ER, resulting in the reduction of the ratio of 155 kDa/135 kDa. In addition, the abundance of UPR-related proteins in the KCNH2A561V group was higher compared with the KCNH2wt+KCNH2A561V group. The 'cysteine biosynthetic activity' of GO:0019344 process and the 'positive regulation of cytoplasmic translation activity' of GO:2000767 process in the KCNH2A561V group were higher compared with the KCNH2wt+KCNH2A561V group. Hence, co-expression of wild-type and A561V mutant KCNH2 in 293 cells activated the UPR process, which led to the inhibition of protein translation and synthesis, in turn inhibiting the expression of KCNH2. These results provided a theoretical basis for clinical treatment of Long QT syndrome.
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Affiliation(s)
- B Chen
- Emergency Medical Center, Ningbo Yinzhou No. 2 Hospital, Ningbo, Zhejiang, China; Department of General Surgery, Ningbo No.2 Hospital, Ningbo, China. ; Department of Cardiology, Ningbo Medical Center LiHuiLi Hospital, Ningbo, China.
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25
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Venkateshappa R, Hunter DV, Muralidharan P, Nagalingam RS, Huen G, Faizi S, Luthra S, Lin E, Cheng YM, Hughes J, Khelifi R, Dhunna DP, Johal R, Sergeev V, Shafaattalab S, Julian LM, Poburko DT, Laksman Z, Tibbits GF, Claydon TW. Targeted activation of human ether-à-go-go-related gene channels rescues electrical instability induced by the R56Q+/- long QT syndrome variant. Cardiovasc Res 2023; 119:2522-2535. [PMID: 37739930 PMCID: PMC10676460 DOI: 10.1093/cvr/cvad155] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 06/22/2023] [Accepted: 07/10/2023] [Indexed: 09/24/2023] Open
Abstract
AIMS Long QT syndrome type 2 (LQTS2) is associated with inherited variants in the cardiac human ether-à-go-go-related gene (hERG) K+ channel. However, the pathogenicity of hERG channel gene variants is often uncertain. Using CRISPR-Cas9 gene-edited hiPSC-derived cardiomyocytes (hiPSC-CMs), we investigated the pathogenic mechanism underlying the LQTS-associated hERG R56Q variant and its phenotypic rescue by using the Type 1 hERG activator, RPR260243. METHODS AND RESULTS The above approaches enable characterization of the unclear causative mechanism of arrhythmia in the R56Q variant (an N-terminal PAS domain mutation that primarily accelerates channel deactivation) and translational investigation of the potential for targeted pharmacologic manipulation of hERG deactivation. Using perforated patch clamp electrophysiology of single hiPSC-CMs, programmed electrical stimulation showed that the hERG R56Q variant does not significantly alter the mean action potential duration (APD90). However, the R56Q variant increases the beat-to-beat variability in APD90 during pacing at constant cycle lengths, enhances the variance of APD90 during rate transitions, and increases the incidence of 2:1 block. During paired S1-S2 stimulations measuring electrical restitution properties, the R56Q variant was also found to increase the variability in rise time and duration of the response to premature stimulations. Application of the hERG channel activator, RPR260243, reduces the APD variance in hERG R56Q hiPSC-CMs, reduces the variability in responses to premature stimulations, and increases the post-repolarization refractoriness. CONCLUSION Based on our findings, we propose that the hERG R56Q variant leads to heterogeneous APD dynamics, which could result in spatial dispersion of repolarization and increased risk for re-entry without significantly affecting the average APD90. Furthermore, our data highlight the antiarrhythmic potential of targeted slowing of hERG deactivation gating, which we demonstrate increases protection against premature action potentials and reduces electrical heterogeneity in hiPSC-CMs.
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Affiliation(s)
- Ravichandra Venkateshappa
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Diana V Hunter
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Priya Muralidharan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Raghu S Nagalingam
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
- Cellular and Regenerative Medicine Centre, British Columbia Children’s Hospital Research Institute, 938 W 28th Ave, Vancouver, BC, Canada V5Z 4H4
| | - Galvin Huen
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Shoaib Faizi
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Shreya Luthra
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Eric Lin
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Yen May Cheng
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Julia Hughes
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Rania Khelifi
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Daman Parduman Dhunna
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Raj Johal
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Valentine Sergeev
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Sanam Shafaattalab
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Lisa M Julian
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Damon T Poburko
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Zachary Laksman
- Department of Medicine, School of Biomedical Engineering, University of British Columbia, 2194 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
| | - Glen F Tibbits
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
- Cellular and Regenerative Medicine Centre, British Columbia Children’s Hospital Research Institute, 938 W 28th Ave, Vancouver, BC, Canada V5Z 4H4
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Tom W Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
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26
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Furutani K. Facilitation of hERG Activation by Its Blocker: A Mechanism to Reduce Drug-Induced Proarrhythmic Risk. Int J Mol Sci 2023; 24:16261. [PMID: 38003453 PMCID: PMC10671758 DOI: 10.3390/ijms242216261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/08/2023] [Accepted: 11/12/2023] [Indexed: 11/26/2023] Open
Abstract
Modulation of the human Ether-à-go-go-Related Gene (hERG) channel, a crucial voltage-gated potassium channel in the repolarization of action potentials in ventricular myocytes of the heart, has significant implications on cardiac electrophysiology and can be either antiarrhythmic or proarrhythmic. For example, hERG channel blockade is a leading cause of long QT syndrome and potentially life-threatening arrhythmias, such as torsades de pointes. Conversely, hERG channel blockade is the mechanism of action of Class III antiarrhythmic agents in terminating ventricular tachycardia and fibrillation. In recent years, it has been recognized that less proarrhythmic hERG blockers with clinical potential or Class III antiarrhythmic agents exhibit, in addition to their hERG-blocking activity, a second action that facilitates the voltage-dependent activation of the hERG channel. This facilitation is believed to reduce the proarrhythmic potential by supporting the final repolarizing of action potentials. This review covers the pharmacological characteristics of hERG blockers/facilitators, the molecular mechanisms underlying facilitation, and their clinical significance, as well as unresolved issues and requirements for research in the fields of ion channel pharmacology and drug-induced arrhythmias.
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Affiliation(s)
- Kazuharu Furutani
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, 180 Nishihama-Boji, Yamashiro-cho, Tokushima 770-8514, Japan
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27
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Montalbano A, Sala C, Altadonna GC, Becchetti A, Arcangeli A. High throughput clone screening on overexpressed hERG1 and Kv1.3 potassium channels using ion channel reader (ICR) label free technology. Heliyon 2023; 9:e20112. [PMID: 37767500 PMCID: PMC10520782 DOI: 10.1016/j.heliyon.2023.e20112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/27/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
Pharmacological studies aimed at the development of newly synthesized drugs directed against ion channels (as well as genetic studies of ion channel mutations) involve the development and use of transfected cells. However, the identification of the best clone, in terms of transfection efficiency, is often a time consuming procedure when performed through traditional methods such as manual patch-clamp. On the other hand, the use of other faster techniques, such as for example the IF, are not informative on the effective biological functionality of the transfected ion channel(s). In the present work, we used the high throughput automated ion channel reader (ICR) technology (ICR8000 Aurora Biomed Inc.) that combine atomic absorption spectroscopy with a patented microsampling process to accurately measure ion flux in cell-based screening assays. This technology indeed helped us to evaluate the transfection efficiency of hERG1 and hKv1.3 channels respectively on the HEK-293 and CHO cellular models. Moreover, as proof of the validity of this innovative method, we have corroborated these data with the functional characterization of the potassium currents carried out by the same clones through patch-clamp recordings. The results obtained in our study are promising and represent a valid methodological strategy to screen a large number of clones simultaneously and to pharmacologically evaluate their functionality within an extremely faster timeframe.
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Affiliation(s)
- Alberto Montalbano
- Department of Experimental and Clinical Medicine, University of Florence, I-50134, Florence, Italy
| | - Cesare Sala
- Department of Experimental and Clinical Medicine, University of Florence, I-50134, Florence, Italy
| | | | - Andrea Becchetti
- University of Milano-Bicocca, Department of Biotechnology and Biosciences, Piazza della Scienza 2, I-20126, Milano, Italy
| | - Annarosa Arcangeli
- Department of Experimental and Clinical Medicine, University of Florence, I-50134, Florence, Italy
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28
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Campagna N, Wall E, Lee K, Guo J, Li W, Yang T, Baranchuk A, El-Diasty M, Zhang S. Differential Effects of Remdesivir and Lumacaftor on Homomeric and Heteromeric hERG Channels. Mol Pharmacol 2023; 104:164-173. [PMID: 37419691 DOI: 10.1124/molpharm.123.000708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/31/2023] [Accepted: 06/08/2023] [Indexed: 07/09/2023] Open
Abstract
The human ether-a-go-go-related gene (hERG) encodes for the pore-forming subunit of the channel that conducts the rapidly activating delayed K+ current (IKr) in the heart. The hERG channel is important for cardiac repolarization, and reduction of its expression in the plasma membrane due to mutations causes long QT syndrome type 2 (LQT2). As such, promoting hERG membrane expression is a strategy to rescue mutant channel function. In the present study, we applied patch clamp, western blots, immunocytochemistry, and quantitative reverse transcription polymerase chain reaction techniques to investigate the rescue effects of two drugs, remdesivir and lumacaftor, on trafficking-defective mutant hERG channels. As our group has recently reported that the antiviral drug remdesivir increases wild-type (WT) hERG current and surface expression, we studied the effects of remdesivir on trafficking-defective LQT2-causing hERG mutants G601S and R582C expressed in HEK293 cells. We also investigated the effects of lumacaftor, a drug used to treat cystic fibrosis, that promotes CFTR protein trafficking and has been shown to rescue membrane expression of some hERG mutations. Our results show that neither remdesivir nor lumacaftor rescued the current or cell-surface expression of homomeric mutants G601S and R582C. However, remdesivir decreased while lumacaftor increased the current and cell-surface expression of heteromeric channels formed by WT hERG and mutant G601S or R582C hERG. We concluded that drugs can differentially affect homomeric WT and heteromeric WT+G601S (or WT+R582C) hERG channels. These findings extend our understanding of drug-channel interaction and may have clinical implications for patients with hERG mutations. SIGNIFICANCE STATEMENT: Various naturally occurring mutations in a cardiac potassium channel called hERG can impair channel function by decreasing cell-surface channel expression, resulting in cardiac electrical disturbances and even sudden cardiac death. Promotion of cell-surface expression of mutant hERG channels represents a strategy to rescue channel function. This work demonstrates that drugs such as remdesivir and lumacaftor can differently affect homomeric and heteromeric mutant hERG channels, which have biological and clinical implications.
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Affiliation(s)
- Noah Campagna
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Erika Wall
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Kevin Lee
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Jun Guo
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Wentao Li
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Tonghua Yang
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Adrian Baranchuk
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Mohammad El-Diasty
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences (N.C., E.W., K.L., J.G., W.L., T.Y., S.Z.); Division of Cardiology, Department of Medicine (A.B.); and Division of Cardiac Surgery, Department of Surgery (M.E.-D.), Queen's University, Kingston, Ontario, Canada
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Docken SS, Clancy CE, Lewis TJ. Rate-dependent effects of state-specific sodium channel blockers in cardiac tissue: Insights from idealized models. J Theor Biol 2023; 573:111595. [PMID: 37562674 DOI: 10.1016/j.jtbi.2023.111595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 06/08/2023] [Accepted: 08/01/2023] [Indexed: 08/12/2023]
Abstract
A common side effect of pharmaceutical drugs is an increased propensity for cardiac arrhythmias. Many drugs bind to cardiac ion-channels in a state-specific manner, which alters the ionic conductances in complicated ways, making it difficult to identify the mechanisms underlying pro-arrhythmic drug effects. To better understand the fundamental mechanisms underlying the diverse effects of state-dependent sodium (Na+) channel blockers on cellular excitability, we consider two canonical motifs of drug-ion-channel interactions and compare the effects of Na+ channel blockers on the rate-dependence of peak upstroke velocity, conduction velocity, and vulnerable window size. In the literature, both motifs are referred to as "guarded receptor," but here we distinguish between state-specific binding that does not alter channel gating (referred to here as "guarded receptor") and state-specific binding that blocks certain gating transitions ("gate immobilization"). For each drug binding motif, we consider drugs that bind to the inactivated state and drugs that bind to the non-inactivated state of the Na+ channel. Exploiting the idealized nature of the canonical binding motifs, we identify the fundamental mechanisms underlying the effects on excitability of the various binding interactions. Specifically, we derive the voltage-dependence of the drug binding time constants and the equilibrium fractions of channels bound to drug, and we then derive a formula that incorporates these time constants and equilibrium fractions to elucidate the fundamental mechanisms. In the case of charged drug, we find that drugs that bind to inactivated channels exhibit greater rate-dependence than drugs that bind to non-inactivated channels. For neutral drugs, the effects of guarded receptor interactions are rate-independent, and we describe a novel mechanism for reverse rate-dependence resulting from neutral drug binding to non-inactivated channels via the gate immobilization motif.
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Affiliation(s)
- Steffen S Docken
- Department of Mathematics, University of California Davis, Davis, CA, USA; Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA.
| | - Colleen E Clancy
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Timothy J Lewis
- Department of Mathematics, University of California Davis, Davis, CA, USA
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Santini L, Duranti C, Palandri C, Giammarino L, Musumeci M, Carlucci L, Capitani C, Colasurdo R, Recchia F, Cerbai E, Coppini R, Arcangeli A. Cardiac safety assessment of a novel recombinant bispecific antibody targeting the ether-à-go-go related gene 1 (hERG1)-β1 integrin macromolecular complex. Front Pharmacol 2023; 14:1237431. [PMID: 37767396 PMCID: PMC10520717 DOI: 10.3389/fphar.2023.1237431] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 08/17/2023] [Indexed: 09/29/2023] Open
Abstract
Introduction: In the last decades, mounting evidence has pointed out the human ether-á-go-go-related gene (hERG1) potassium channel as a novel biomarker in human cancers. However, hERG1 sustains the cardiac repolarizing current IKr and its blockade can induce a prolonged QT interval at the ECG, which increases the risk of life-threatening arrhythmias. This represents a major hindrance for targeting hERG1 for antineoplastic therapeutic purposes. Based on our discovery that hERG1 resides in a macromolecular complex with the β1 subunit of integrin adhesion receptors only in tumors, and not in the heart, we generated (and patented WO2019/015936) a novel engineered, single chain, bispecific antibody in the format of a diabody (scDb-hERG1-β1). This antibody has been proven to target with high affinity the hERG1/β1 integrin complex and to exert a good antineoplastic activity in preclinical mouse models. Methods: In the present study, we evaluated the cardiac safety of the scDb-hERG1-β1, determining the action potential duration (APD) of human cardiomyocytes, either atrial (from valve-disease patients) or ventricular (from aortic stenosis patients). Cardiac cells were incubated in vitro with i) the scDb-hERG1-β1, ii) the full length anti-hERG1 monoclonal antibody (mAb-hERG1) and iii) its single chain Fragment variable derivative (scFv-hERG1), from which the scDb-hERG1-β1 was assembled. All the tests were performed before and after treatment with the specific hERG1 blocker E4031. In addition, we have performed preliminary experiments, analyzing the effects of the scDb-hERG1/β1 in vivo measuring the QT interval length of the surface ECG after its injection intravenously in farm-pigs. Results: The scDb-hERG1-β1 did not produce any lengthening of APD compared to control (vehicle) conditions, either in atrial or ventricular cardiomyocytes, whereas both the hERG1-mAb and the scFv-hERG1 produced a significant APD prolongation. The addition of E4031 further prolonged APD. The scDb-hERG1-β1 did not produce any alterations of the QT (and QTc) interval values, once injected intravenously in farm pigs. Discussion: Overall, the above evidences plead for the cardiac safety of the scDb-hERG1-β1, suggesting that an application of this antibody for anti-cancer therapy will be untainted by cardiotoxicity.
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Affiliation(s)
- Lorenzo Santini
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Claudia Duranti
- Department of Experimental and Clinical Medicine, Section of Internal Medicine, University of Florence, Florence, Italy
| | - Chiara Palandri
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Lucrezia Giammarino
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Monica Musumeci
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Lucia Carlucci
- Institute of Life Sciences, Scuola Superiore Sant’Anna, Pisa, Italy
| | - Chiara Capitani
- Department of Experimental and Clinical Medicine, Section of Internal Medicine, University of Florence, Florence, Italy
- Department of Medical Biotechnology, University of Siena, Siena, Italy
| | - Rossella Colasurdo
- Department of Experimental and Clinical Medicine, Section of Internal Medicine, University of Florence, Florence, Italy
- Department of Medical Biotechnology, University of Siena, Siena, Italy
| | - Fabio Recchia
- Institute of Life Sciences, Scuola Superiore Sant’Anna, Pisa, Italy
| | - Elisabetta Cerbai
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Raffaele Coppini
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Annarosa Arcangeli
- Department of Experimental and Clinical Medicine, Section of Internal Medicine, University of Florence, Florence, Italy
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Christian S, Dzwiniel T. Principles of Genetic Counseling in Inherited Heart Conditions. Card Electrophysiol Clin 2023; 15:229-239. [PMID: 37558294 DOI: 10.1016/j.ccep.2023.05.001] [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] [Indexed: 08/11/2023]
Abstract
Cardiac genetic counseling is the process of helping individuals adapt to a personal diagnosis or family history of an inherited heart condition. The process is shown to benefit patients and includes specialized skills, such as counseling children and interpreting complex genetic results. Emerging areas include: evolving service delivery models for caring for patients and communicating risk to relatives, new areas of need including postmortem molecular autopsy, and new populations of individuals found to carry a likely pathogenic/pathogenic cardiac variant identified through genomic screening. This article provides an overview of the cardiac genetic counseling process and evolving areas in the field.
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Affiliation(s)
- Susan Christian
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada.
| | - Tara Dzwiniel
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
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Xing J, Gumerov VM, Zhulin IB. Origin and functional diversification of PAS domain, a ubiquitous intracellular sensor. SCIENCE ADVANCES 2023; 9:eadi4517. [PMID: 37647406 PMCID: PMC10468136 DOI: 10.1126/sciadv.adi4517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/28/2023] [Indexed: 09/01/2023]
Abstract
Signal perception is a key function in regulating biological activities and adapting to changing environments. Per-Arnt-Sim (PAS) domains are ubiquitous sensors found in diverse receptors in bacteria, archaea, and eukaryotes, but their origins, distribution across the tree of life, and extent of their functional diversity are not fully characterized. Here, we show that using sequence conservation and structural information, it is possible to propose specific and potential functions for a large portion of nearly 3 million PAS domains. Our analysis suggests that PAS domains originated in bacteria and were horizontally transferred to archaea and eukaryotes. We reveal that gas sensing via a heme cofactor evolved independently in several lineages, whereas redox and light sensing via flavin adenine dinucleotide and flavin mononucleotide cofactors have the same origin. The close relatedness of human PAS domains to those in bacteria provides an opportunity for drug design by exploring potential natural ligands and cofactors for bacterial homologs.
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Affiliation(s)
- Jiawei Xing
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH USA
| | - Vadim M. Gumerov
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH USA
| | - Igor B. Zhulin
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
- Translational Data Analytics Institute, The Ohio State University, Columbus, OH USA
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Zhou Y, Hao N, Sander JW, Lin X, Xiong W, Zhou D. KCNH2 variants in a family with epilepsy and long QT syndrome: A case report and literature review. Epileptic Disord 2023; 25:492-499. [PMID: 36946251 DOI: 10.1002/epd2.20046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 03/07/2023] [Accepted: 03/12/2023] [Indexed: 03/23/2023]
Abstract
OBJECTIVE Genes associated with Long QT syndromes (LQTS), such as KCNQ1, KCNH2, and SCN5A, are common causes of epilepsy. The Arg 744* variant of KCNH2 has been previously reported in people with epilepsy or LQTS, but none of these patients were reported to simultaneously suffer from epilepsy and LQTS. Herein, we report the case of a family with epilepsy and cardiac disorders. METHOD The proband, a 25-year-old woman, with a family history of epilepsy and LQTS was followed at West China Hospital. The proband experienced her first seizure at the age of seven. Video electroencephalograms (vEEGs) showed epileptic discharges. Her 24-h dynamic electrocardiograms 2 (ECGs) showed QTc prolongation. The proband's mother, who is 50 years old, had her first generalized tonic-clonic seizure (GTCS) at the age of 18 years old. After she gave birth at the age of 25, the frequency of seizures increased, so antiepileptic therapy was initiated. When she was 28 years old, she complained of palpitations and syncope for the first time, and QTc prolongation was detected on her 24-h dynamic ECGs. The proband's grandmother also had complaints of palpitations and syncope at the age of 73. Her 24-h dynamic ECGs indicated supraventricular arrhythmia, with the lowest heart rate being 41 bpm, so she agreed to a pacemaker. Considering the young patient's family history, blood samples of the patient and her parents were collected for genetic analysis. RESULTS A heterozygous variant of KCNH2 [c.2230 (exon9) C>T, p. Arg744Ter, 416, NM_000238, rs189014161] was found in the proband and her mother. According to the guidelines of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology, we classified the KCNH2 variant as pathogenic. SIGNIFICANCE This study expands the clinical phenotype of the Arg 744* KCNH2 pathogenic variant. In the context of channelopathies, because of the genetic susceptibility of the brain and the heart, the risk of comorbidity should be considered. This also indicates the importance of precise antiepileptic drug (AED) management and regular ECG monitoring for patients with channelopathies.
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Affiliation(s)
- Yu Zhou
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
| | - Nanya Hao
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
| | - Josemir W Sander
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- Chalfont Centre for Epilepsy, Chalfont St Peter, United Kingdom & Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - Xu Lin
- Department of Neurology, The Affiliated Chengdu 363 Hospital of Southwest Medical University, Chengdu, Sichuan, China
| | - Weixi Xiong
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
| | - Dong Zhou
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
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Wang H, Zhu G, Izu LT, Chen-Izu Y, Ono N, Altaf-Ul-Amin MD, Kanaya S, Huang M. On QSAR-based cardiotoxicity modeling with the expressiveness-enhanced graph learning model and dual-threshold scheme. Front Physiol 2023; 14:1156286. [PMID: 37228825 PMCID: PMC10203956 DOI: 10.3389/fphys.2023.1156286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/05/2023] [Indexed: 05/27/2023] Open
Abstract
Introduction: Given the direct association with malignant ventricular arrhythmias, cardiotoxicity is a major concern in drug design. In the past decades, computational models based on the quantitative structure-activity relationship have been proposed to screen out cardiotoxic compounds and have shown promising results. The combination of molecular fingerprint and the machine learning model shows stable performance for a wide spectrum of problems; however, not long after the advent of the graph neural network (GNN) deep learning model and its variant (e.g., graph transformer), it has become the principal way of quantitative structure-activity relationship-based modeling for its high flexibility in feature extraction and decision rule generation. Despite all these progresses, the expressiveness (the ability of a program to identify non-isomorphic graph structures) of the GNN model is bounded by the WL isomorphism test, and a suitable thresholding scheme that relates directly to the sensitivity and credibility of a model is still an open question. Methods: In this research, we further improved the expressiveness of the GNN model by introducing the substructure-aware bias by the graph subgraph transformer network model. Moreover, to propose the most appropriate thresholding scheme, a comprehensive comparison of the thresholding schemes was conducted. Results: Based on these improvements, the best model attains performance with 90.4% precision, 90.4% recall, and 90.5% F1-score with a dual-threshold scheme (active: < 1 μ M ; non-active: > 30 μ M ). The improved pipeline (graph subgraph transformer network model and thresholding scheme) also shows its advantages in terms of the activity cliff problem and model interpretability.
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Affiliation(s)
- Huijia Wang
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Guangxian Zhu
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Leighton T. Izu
- Department of Pharmacology, University of California, Davis, CA, United States
| | - Ye Chen-Izu
- Department of Biomedical Engineering, University of California, Davis, CA, United States
| | - Naoaki Ono
- Data Science Center, Nara Institute of Science and Technology, Ikoma, Japan
| | - MD Altaf-Ul-Amin
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Shigehiko Kanaya
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Ming Huang
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
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35
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Zheng Z, Song Y, Tan X. Deciphering hERG Mutation in Long QT Syndrome Type 2 Using Antisense Oligonucleotide-Mediated Techniques: Lessons from Cystic Fibrosis. Heart Rhythm 2023:S1547-5271(23)02180-X. [PMID: 37121422 DOI: 10.1016/j.hrthm.2023.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/18/2023] [Accepted: 04/25/2023] [Indexed: 05/02/2023]
Abstract
Long QT syndrome type 2 (LQT2) is a genetic disorder caused by mutations in the KCNH2 gene, also known as the human ether-a-go-go-related gene (hERG). Over 30% of hERG mutations result in a premature termination codon (PTC) that triggers a process called nonsense-mediated mRNA decay (NMD), where the mRNA transcript is degraded. NMD is a quality control mechanism that removes faulty mRNA to prevent the translation of truncated proteins. Recent advances in antisense oligonucleotide (ASO) technology in the field of cystic fibrosis (CF) have yielded significant progress, including the ASO-mediated comprehensive characterization of key NMD factors and exon-skipping therapy. These advances have contributed to our understanding of the role of PTC-containing mutations in disease phenotypes and have also led to the development of potentially useful therapeutic strategies. Historically, studies of CF have provided valuable insights for the research on LQT2, particularly concerning increasing the expression of hERG. In this article, we outline the current state of knowledge regarding ASO, NMD, and hERG and discuss the introduction of ASO technology in the CF to elucidate the pathogenic mechanisms through targeting NMD. We also discuss the potential clinical therapeutic benefits and limitations of ASO for the management of LQT2. By drawing on lessons learned from CF research, we explore the potential translational values of these advances into LQT2 studies.
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Affiliation(s)
- Zequn Zheng
- Department of Cardiology, Shantou University Medical College, Shantou, China; Department of Cardiology, First Affiliated Hospital of Shantou University Medical College, Shantou, China; Clinical Research Center, First Affiliated Hospital of Shantou University Medical College, Shantou, China.
| | - Yongfei Song
- Ningbo Institute for Medicine &Biomedical Engineering Combined Innovation, Ningbo, China
| | - Xuerui Tan
- Department of Cardiology, First Affiliated Hospital of Shantou University Medical College, Shantou, China; Clinical Research Center, First Affiliated Hospital of Shantou University Medical College, Shantou, China.
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36
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Yan Z, Zhong L, Zhu W, Chung SK, Hou P. Chinese herbal medicine for the treatment of cardiovascular diseases ─ targeting cardiac ion channels. Pharmacol Res 2023; 192:106765. [PMID: 37075871 DOI: 10.1016/j.phrs.2023.106765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/04/2023] [Accepted: 04/12/2023] [Indexed: 04/21/2023]
Abstract
Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality, imposing an increasing global health burden. Cardiac ion channels (voltage-gated NaV, CaV, KVs, and others) synergistically shape the cardiac action potential (AP) and control the heartbeat. Dysfunction of these channels, due to genetic mutations, transcriptional or post-translational modifications, may disturb the AP and lead to arrhythmia, a major risk for CVD patients. Although there are five classes of anti-arrhythmic drugs available, they can have varying levels of efficacies and side effects on patients, possibly due to the complex pathogenesis of arrhythmias. As an alternative treatment option, Chinese herbal remedies have shown promise in regulating cardiac ion channels and providing anti-arrhythmic effects. In this review, we first discuss the role of cardiac ion channels in maintaining normal heart function and the pathogenesis of CVD, then summarize the classification of Chinese herbal compounds, and elaborate detailed mechanisms of their efficacy in regulating cardiac ion channels and in alleviating arrhythmia and CVD. We also address current limitations and opportunities for developing new anti-CVD drugs based on Chinese herbal medicines.
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Affiliation(s)
- Zhenzhen Yan
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China
| | - Ling Zhong
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China
| | - Wandi Zhu
- Cardiovascular Medicine Division and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Sookja Kim Chung
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China; Faculty of Medicine & Faculty of Innovation Engineering at Macau University of Science and Technology, Taipa, Macao SAR, China; State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
| | - Panpan Hou
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China; Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China.
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37
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Mehta A, Patel BM. Long-acting opioids and cardiovascular diseases: Help or hindrance! Vascul Pharmacol 2023; 149:107144. [PMID: 36740214 DOI: 10.1016/j.vph.2023.107144] [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: 12/02/2022] [Accepted: 01/25/2023] [Indexed: 02/05/2023]
Abstract
Opioids are widely being used for chronic pain management, cough and diarrhea suppressants, anesthetic agents, and opioid de-addiction therapy. Opioid receptors, present in the central nervous system and peripheral tissues, are documented to regulate several cardiac functions through different signaling pathways. Long-acting opioids (LAO) have been successfully evaluated for their beneficial effects in various cardiovascular diseases viz. myocardial infarction, ischemic reperfusion injuries, atherosclerosis etc. However, on the other hand, several research studies pointed towards the harmful effects of LAOs which are mainly associated with QTc prolongation, torsade de pointes, ventricular arrhythmias, and cardiac arrest. This review shall familiarize readers with the benefits as well as the harmful effects of long-acting opioids in cardiovascular diseases. We have also provided an overview of cardiac opioid receptors, endogenous cardiac opioid peptides, and regulation of cardiovascular functions by central and cardiac opioid receptors.
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Affiliation(s)
- Ankita Mehta
- Labcorp Central Laboratory Services Limited Partnership, Bangalore, India
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38
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Alexander C, Bishop MJ, Gilchrist RJ, Burton FL, Smith GL, Myles RC. Initiation of ventricular arrhythmia in the acquired long QT syndrome. Cardiovasc Res 2023; 119:465-476. [PMID: 35727943 PMCID: PMC10064840 DOI: 10.1093/cvr/cvac103] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/25/2022] [Accepted: 06/02/2022] [Indexed: 11/15/2022] Open
Abstract
AIMS Long QT syndrome (LQTS) carries a risk of life-threatening polymorphic ventricular tachycardia (Torsades de Pointes, TdP) and is a major cause of premature sudden cardiac death. TdP is induced by R-on-T premature ventricular complexes (PVCs), thought to be generated by cellular early-afterdepolarisations (EADs). However, EADs in tissue require cellular synchronisation, and their role in TdP induction remains unclear. We aimed to determine the mechanism of TdP induction in rabbit hearts with acquired LQTS (aLQTS). METHODS AND RESULTS Optical mapping of action potentials (APs) and intracellular Ca2+ was performed in Langendorff-perfused rabbit hearts (n = 17). TdP induced by R-on-T PVCs was observed during aLQTS (50% K+/Mg++ & E4031) conditions in all hearts (P < 0.0001 vs. control). Islands of AP prolongation bounded by steep voltage gradients (VGs) were consistently observed before arrhythmia and peak VGs were more closely related to the PVC upstroke than EADs, both temporally (7 ± 5 ms vs. 44 ± 27 ms, P < 0.0001) and spatially (1.0 ± 0.7 vs. 3.6 ± 0.9 mm, P < 0.0001). PVCs were initiated at estimated voltages of ∼ -40 mV and had upstroke dF/dtmax and Vm-Ca2+ dynamics compatible with ICaL activation. Computational simulations demonstrated that PVCs could arise directly from VGs, through electrotonic triggering of ICaL. In experiments and the model, sub-maximal L-type Ca2+ channel (LTCC) block (200 nM nifedipine and 90% gCaL, respectively) abolished both PVCs and TdP in the continued presence of aLQTS. CONCLUSION These data demonstrate that ICaL activation at sites displaying steep VGs generates the PVCs which induce TdP, providing a mechanism and rationale for LTCC blockers as a novel therapeutic approach in LQTS.
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Affiliation(s)
- Cherry Alexander
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Martin J Bishop
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Rebecca J Gilchrist
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Francis L Burton
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Rachel C Myles
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
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Kovács ZM, Óvári J, Dienes C, Magyar J, Bányász T, Nánási PP, Horváth B, Feher A, Varga Z, Szentandrássy N. ABT-333 (Dasabuvir) Increases Action Potential Duration and Provokes Early Afterdepolarizations in Canine Left Ventricular Cells via Inhibition of IKr. Pharmaceuticals (Basel) 2023; 16:ph16040488. [PMID: 37111245 PMCID: PMC10143825 DOI: 10.3390/ph16040488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/17/2023] [Accepted: 03/22/2023] [Indexed: 03/29/2023] Open
Abstract
ABT-333 (dasabuvir) is an antiviral agent used in hepatitis C treatment. The molecule, similarly to some inhibitors of hERG channels, responsible for the delayed rectifier potassium current (IKr), contains the methanesulfonamide group. Reduced IKr current leads to long QT syndrome and early afterdepolarizations (EADs), therefore potentially causing life-threatening arrhythmias and sudden cardiac death. Our goal was to investigate the acute effects of ABT-333 in enzymatically isolated canine left ventricular myocardial cells. Action potentials (APs) and ion currents were recorded with a sharp microelectrode technique and whole-cell patch clamp, respectively. Application of 1 μM ABT-333 prolonged the AP in a reversible manner. The maximal rates of phases 0 and 1 were irreversibly decreased. Higher ABT-333 concentrations caused larger AP prolongation, elevation of the early plateau potential, and reduction of maximal rates of phases 0, 1, and 3. EADs occurred in some cells in 3–30 μM ABT-333 concentrations. The 10 μM ABT-333-sensitive current, recorded with AP voltage clamp, contained a late outward component corresponding to IKr and an early outward one corresponding to transient outward potassium current (Ito). ABT-333 reduced hERG-channel-mediated ion current in a concentration-dependent, partially reversible manner with a half-inhibitory concentration of 3.2 μM. As the therapeutic plasma concentration of ABT-333 is 1 nM, the arrhythmic risk of ABT-333 is very low, even in the case of drug overdose.
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40
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Farm HJ, Clerx M, Cooper F, Polonchuk L, Wang K, Gavaghan DJ, Lei CL. Importance of modelling hERG binding in predicting drug-induced action potential prolongations for drug safety assessment. Front Pharmacol 2023; 14:1110555. [PMID: 37021055 PMCID: PMC10067903 DOI: 10.3389/fphar.2023.1110555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/22/2023] [Indexed: 03/30/2023] Open
Abstract
Reduction of the rapid delayed rectifier potassium current (IKr) via drug binding to the human Ether-à-go-go-Related Gene (hERG) channel is a well recognised mechanism that can contribute to an increased risk of Torsades de Pointes. Mathematical models have been created to replicate the effects of channel blockers, such as reducing the ionic conductance of the channel. Here, we study the impact of including state-dependent drug binding in a mathematical model of hERG when translating hERG inhibition to action potential changes. We show that the difference in action potential predictions when modelling drug binding of hERG using a state-dependent model versus a conductance scaling model depends not only on the properties of the drug and whether the experiment achieves steady state, but also on the experimental protocols. Furthermore, through exploring the model parameter space, we demonstrate that the state-dependent model and the conductance scaling model generally predict different action potential prolongations and are not interchangeable, while at high binding and unbinding rates, the conductance scaling model tends to predict shorter action potential prolongations. Finally, we observe that the difference in simulated action potentials between the models is determined by the binding and unbinding rate, rather than the trapping mechanism. This study demonstrates the importance of modelling drug binding and highlights the need for improved understanding of drug trapping which can have implications for the uses in drug safety assessment.
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Affiliation(s)
- Hui Jia Farm
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Michael Clerx
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Fergus Cooper
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
| | - Liudmila Polonchuk
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Ken Wang
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - David J. Gavaghan
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
- Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
- *Correspondence: David J. Gavaghan, ; Chon Lok Lei,
| | - Chon Lok Lei
- Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, China
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Macau, Macau, China
- *Correspondence: David J. Gavaghan, ; Chon Lok Lei,
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41
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Bassetto CAZ, Costa F, Guardiani C, Bezanilla F, Giacomello A. Noncanonical electromechanical coupling paths in cardiac hERG potassium channel. Nat Commun 2023; 14:1110. [PMID: 36849440 PMCID: PMC9971164 DOI: 10.1038/s41467-023-36730-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 02/15/2023] [Indexed: 03/01/2023] Open
Abstract
Voltage-gated potassium channels are involved in many physiological processes such as nerve impulse transmission, the heartbeat, and muscle contraction. However, for many of them the molecular determinants of the gating mechanism remain elusive. Here, using a combination of theoretical and experimental approaches, we address this problem focusing on the cardiac hERG potassium channel. Network analysis of molecular dynamics trajectories reveals the presence of a kinematic chain of residues that couples the voltage sensor domain to the pore domain and involves the S4/S1 and S1/S5 subunit interfaces. Mutagenesis experiments confirm the role of these residues and interfaces in the activation and inactivation mechanisms. Our findings demonstrate the presence of an electromechanical transduction path crucial for the non-domain-swapped hERG channel gating that resembles the noncanonical path identified in domain-swapped K+ channels.
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Affiliation(s)
- Carlos A Z Bassetto
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Flavio Costa
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Rome, Italy
| | - Carlo Guardiani
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Rome, Italy
| | - Francisco Bezanilla
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.
- Centro Interdisciplinario de Neurociencias, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso, Chile.
| | - Alberto Giacomello
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Rome, Italy.
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42
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Cai D, Zheng Z, Jin X, Fu Y, Cen L, Ye J, Song Y, Lian J. The Advantages, Challenges, and Future of Human-Induced Pluripotent Stem Cell Lines in Type 2 Long QT Syndrome. J Cardiovasc Transl Res 2023; 16:209-220. [PMID: 35976484 DOI: 10.1007/s12265-022-10298-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 07/23/2022] [Indexed: 02/05/2023]
Abstract
Type 2 long QT syndrome (LQT2) is the second most common subtype of long QT syndrome and is caused by mutations in KCHN2 encoding the rapidly activating delayed rectifier potassium channel vital for ventricular repolarization. Sudden cardiac death is a sentinel event of LQT2. Preclinical diagnosis by genetic testing is potentially life-saving.Traditional LQT2 models cannot wholly recapitulate genetic and phenotypic features; therefore, there is a demand for a reliable experimental model. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) meet this challenge. This review introduces the advantages of the hiPSC-CM model over the traditional model and discusses how hiPSC-CM and gene editing are used to decipher mechanisms of LQT2, screen for cardiotoxicity, and identify therapeutic strategies, thus promoting the realization of precision medicine for LQT2 patients.
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Affiliation(s)
- Dihui Cai
- Department of Cardiovascular, Lihuili Hospital Affiliated to Ningbo University, Ningbo University, Zhejiang Province, Ningbo, China
| | - Zequn Zheng
- Department of Cardiovascular, Lihuili Hospital Affiliated to Ningbo University, Ningbo University, Zhejiang Province, Ningbo, China
- Department of Cardiovascular, First Affiliated Hospital of Shantou University Medical College, Shantou, China
| | - Xiaojun Jin
- Department of Cardiovascular, Lihuili Hospital Affiliated to Ningbo University, Ningbo University, Zhejiang Province, Ningbo, China
| | - Yin Fu
- Department of Cardiovascular, Lihuili Hospital Affiliated to Ningbo University, Ningbo University, Zhejiang Province, Ningbo, China
| | - Lichao Cen
- Department of Cardiovascular, Lihuili Hospital Affiliated to Ningbo University, Ningbo University, Zhejiang Province, Ningbo, China
| | - Jiachun Ye
- Department of Cardiovascular, Lihuili Hospital Affiliated to Ningbo University, Ningbo University, Zhejiang Province, Ningbo, China
| | - Yongfei Song
- Department of Cardiovascular, Ningbo Institute of Innovation for Combined Medicine and Engineering, Ningbo, China
| | - Jiangfang Lian
- Department of Cardiovascular, Lihuili Hospital Affiliated to Ningbo University, Ningbo University, Zhejiang Province, Ningbo, China.
- Department of Cardiovascular, Ningbo Institute of Innovation for Combined Medicine and Engineering, Ningbo, China.
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43
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Carss KJ, Deaton AM, Del Rio-Espinola A, Diogo D, Fielden M, Kulkarni DA, Moggs J, Newham P, Nelson MR, Sistare FD, Ward LD, Yuan J. Using human genetics to improve safety assessment of therapeutics. Nat Rev Drug Discov 2023; 22:145-162. [PMID: 36261593 DOI: 10.1038/s41573-022-00561-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2022] [Indexed: 02/07/2023]
Abstract
Human genetics research has discovered thousands of proteins associated with complex and rare diseases. Genome-wide association studies (GWAS) and studies of Mendelian disease have resulted in an increased understanding of the role of gene function and regulation in human conditions. Although the application of human genetics has been explored primarily as a method to identify potential drug targets and support their relevance to disease in humans, there is increasing interest in using genetic data to identify potential safety liabilities of modulating a given target. Human genetic variants can be used as a model to anticipate the effect of lifelong modulation of therapeutic targets and identify the potential risk for on-target adverse events. This approach is particularly useful for non-clinical safety evaluation of novel therapeutics that lack pharmacologically relevant animal models and can contribute to the intrinsic safety profile of a drug target. This Review illustrates applications of human genetics to safety studies during drug discovery and development, including assessing the potential for on- and off-target associated adverse events, carcinogenicity risk assessment, and guiding translational safety study designs and monitoring strategies. A summary of available human genetic resources and recommended best practices is provided. The challenges and future perspectives of translating human genetic information to identify risks for potential drug effects in preclinical and clinical development are discussed.
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Affiliation(s)
| | - Aimee M Deaton
- Amgen, Cambridge, MA, USA.,Alnylam Pharmaceuticals, Cambridge, MA, USA
| | - Alberto Del Rio-Espinola
- Novartis Institutes for BioMedical Research, Basel, Switzerland.,GentiBio Inc., Cambridge, MA, USA
| | | | - Mark Fielden
- Amgen, Thousand Oaks, MA, USA.,Kate Therapeutics, San Diego, CA, USA
| | | | - Jonathan Moggs
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | | | | | - Frank D Sistare
- Merck & Co., West Point, PA, USA.,315 Meadowmont Ln, Chapel Hill, NC, USA
| | - Lucas D Ward
- Amgen, Cambridge, MA, USA. .,Alnylam Pharmaceuticals, Cambridge, MA, USA.
| | - Jing Yuan
- Amgen, Cambridge, MA, USA.,Pfizer, Cambridge, MA, USA
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44
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Schwartz PJ, Sala L. The impact of genetics on the long QT syndrome: myth or reality? Curr Opin Cardiol 2023; 38:149-156. [PMID: 36789771 DOI: 10.1097/hco.0000000000001027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
PURPOSE OF REVIEW To summarize and critically assess the contribution of genetics to the Long QT Syndrome (LQTS), with specific reference to the unraveling of its underlying mechanisms and to its impact on clinical practice. RECENT FINDINGS The evolution towards our current approach to therapy for LQTS patients is examined in terms of risk stratification, gene-specific management, and assessment of the clinical impact that genetic modifiers may have in modulating the natural history of the patients. Glimpses are provided on the newest multidisciplinary approaches to study disease mechanisms, test new candidate drugs and identify precision treatments. SUMMARY It is undeniable that genetics has revolutionized our mechanistic understanding of cardiac channelopathies. Its impact has been enormous but, curiously, the way LQTS patients are being treated today is largely the same that was used in the pregenetic era, even though management has been refined and gene-specific differences allow a more individually tailored antiarrhythmic protection. The synergy of genetic findings with modern in vitro and in silico tools may expand precision treatments; however, they will need to prove more effective than the current therapeutic approaches and equally safe.
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Affiliation(s)
- Peter J Schwartz
- Istituto Auxologico Italiano IRCCS, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics
| | - Luca Sala
- Istituto Auxologico Italiano IRCCS, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics.,Department of Biotechnology and Biosciences, University of Milano - Bicocca, Milan, Italy
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45
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Pettini F, Domene C, Furini S. Early Steps in C-Type Inactivation of the hERG Potassium Channel. J Chem Inf Model 2023; 63:251-258. [PMID: 36512342 PMCID: PMC9832476 DOI: 10.1021/acs.jcim.2c01028] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Fast C-type inactivation confers distinctive functional properties to the hERG potassium channel, and its association to inherited and acquired cardiac arrythmias makes the study of the inactivation mechanism of hERG at the atomic detail of paramount importance. At present, two models have been proposed to describe C-type inactivation in K+-channels. Experimental data and computational work on the bacterial KcsA channel support the hypothesis that C-type inactivation results from a closure of the selectivity filter that sterically impedes ion conduction. Alternatively, recent experimental structures of a mutated Shaker channel revealed a widening of the extracellular portion of the selectivity filter, which might diminish conductance by interfering with the mechanism of ion permeation. Here, we performed molecular dynamics simulations of the wild-type hERG, a non-inactivating mutant (hERG-N629D), and a mutant that inactivates faster than the wild-type channel (hERG-F627Y) to find out which and if any of the two reported C-type inactivation mechanisms applies to hERG. Closure events of the selectivity filter were not observed in any of the simulated trajectories but instead, the extracellular section of the selectivity filter deviated from the canonical conductive structure of potassium channels. The degree of widening of the potassium binding sites at the extracellular entrance of the channel was directly related to the degree of inactivation with hERG-F627Y > wild-type hERG > hERG-N629D. These findings support the hypothesis that C-type inactivation in hERG entails a widening of the extracellular entrance of the channel rather than a closure of the selectivity filter.
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Affiliation(s)
- Francesco Pettini
- Department
of Medical Biotechnologies, University of
Siena, viale Mario Bracci 12, Siena 53100, Italy,Department
of Biotechnology, Chemistry and Pharmacy, University of Siena, viale Mario Bracci 12, Siena 53100, Italy
| | - Carmen Domene
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.,Department
of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K.,
| | - Simone Furini
- Department
of Electrical, Electronic and Information Engineering ″Guglielmo
Marconi”, University of Bologna, via dell’Università
50, Cesena (FC) 47521, Italy,
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46
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Abstract
Long QT syndrome (LQTS) is a detrimental arrhythmia syndrome mainly caused by dysregulated expression or aberrant function of ion channels. The major clinical symptoms of ventricular arrhythmia, palpitations and syncope vary among LQTS subtypes. Susceptibility to malignant arrhythmia is a result of delayed repolarisation of the cardiomyocyte action potential (AP). There are 17 distinct subtypes of LQTS linked to 15 autosomal dominant genes with monogenic mutations. However, due to the presence of modifier genes, the identical mutation may result in completely different clinical manifestations in different carriers. In this review, we describe the roles of various ion channels in orchestrating APs and discuss molecular aetiologies of various types of LQTS. We highlight the usage of patient-specific induced pluripotent stem cell (iPSC) models in characterising fundamental mechanisms associated with LQTS. To mitigate the outcomes of LQTS, treatment strategies are initially focused on small molecules targeting ion channel activities. Next-generation treatments will reap the benefits from development of LQTS patient-specific iPSC platform, which is bolstered by the state-of-the-art technologies including whole-genome sequencing, CRISPR genome editing and machine learning. Deep phenotyping and high-throughput drug testing using LQTS patient-specific cardiomyocytes herald the upcoming precision medicine in LQTS.
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47
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Beheshti M, Rabiei N, Taghizadieh M, Eskandari P, Mollazadeh S, Dadgostar E, Hamblin MR, Salmaninejad A, Emadi R, Mohammadi AH, Mirazei H. Correlations between single nucleotide polymorphisms in obsessive-compulsive disorder with the clinical features or response to therapy. J Psychiatr Res 2023; 157:223-238. [PMID: 36508934 DOI: 10.1016/j.jpsychires.2022.11.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 11/08/2022] [Accepted: 11/18/2022] [Indexed: 11/25/2022]
Abstract
Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric disorder, in which the patient endures intrusive thoughts or is compelled to perform repetitive or ritualized actions. Many cases of OCD are considered to be familial or heritable in nature. It has been shown that a variety of internal and external risk factors are involved in the pathogenesis of OCD. Among the internal factors, genetic modifications play a critical role in the pathophysiological process. Despite many investigations performed to determine the candidate genes, the precise genetic factors involved in the disease remain largely undetermined. The present review summarizes the single nucleotide polymorphisms that have been proposed to be associated with OCD symptoms, early onset disease, neuroimaging results, and response to therapy. This information could help us to draw connections between genetics and OCD symptoms, better characterize OCD in individual patients, understand OCD prognosis, and design more targeted personalized treatment approaches.
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Affiliation(s)
- Masoumeh Beheshti
- Pathophysiology Laboratory, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Nikta Rabiei
- School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Taghizadieh
- Department of Pathology, School of Medicine, Center for Women's Health Research Zahra, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Pariya Eskandari
- Department of Biology, School of Basic Sciences, University of Guilan, Rasht, Iran
| | - Samaneh Mollazadeh
- Natural Products and Medicinal Plants Research Center, North Khorasan University of Medical Sciences, Bojnurd, Iran
| | - Ehsan Dadgostar
- Behavioral Sciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran; Student Research Committee, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Michael R Hamblin
- Laser Research Centre, Faculty of Health Science, University of Johannesburg, Doornfontein, 2028, South Africa
| | - Arash Salmaninejad
- Regenerative Medicine, Organ Procurement and Transplantation Multi Disciplinary Center, Razi Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran; Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Raziye Emadi
- School of Medicine, Kashan University of Medical Sciences, Kashan, Iran.
| | - Amir Hossein Mohammadi
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.
| | - Hamed Mirazei
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.
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48
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Lalaguna L, Ramos-Hernández L, Priori SG, Lara-Pezzi E. Genome Editing and Inherited Cardiac Arrhythmias. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1396:115-127. [DOI: 10.1007/978-981-19-5642-3_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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49
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Vold VA, Glanville S, Klaerke DA, Pedersen PA. pXOOY: A dual-function vector for expression of membrane proteins in Saccharomyces cerevisiae and Xenopus laevis oocytes. PLoS One 2023; 18:e0281868. [PMID: 36809531 PMCID: PMC9942955 DOI: 10.1371/journal.pone.0281868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 02/02/2023] [Indexed: 02/23/2023] Open
Abstract
On the quest for solving structures of membrane proteins by X-ray crystallography or cryo-EM, large quantities of ultra-pure protein are a paramount prerequisite. Obtaining enough protein of such high standard is not a trivial task, especially for difficult-to-express membrane proteins. Producing membrane protein for structural studies is often performed in Escherichia coli or Saccharomyces cerevisiae and is frequently complemented with functional studies. Ion channels and electrogenic receptors are traditionally studied in terms of their electrophysiological behavior, which cannot be performed in neither E. coli nor yeast. Therefore, they are frequently characterized in mammalian cells or in Xenopus laevis oocytes. To avoid generating two different plasmids, we here describe the construction of a dual-function plasmid, pXOOY, for membrane protein production in yeast and for electrophysiology in oocytes. pXOOY was constructed such that all elements required for oocyte expression were copied from the dual Xenopus-mammalian vector pXOOM and meticulously introduced into the high-yield yeast expression vector pEMBLyex4. pXOOY is thus designed to preserve the high yield of protein from pEMBLyex4 while simultaneously permitting in vitro transcription for expression in oocytes. We evaluated the performance of pXOOY by comparing expression of two yeast codon optimized human potassium channels, ohERG and ohSlick (Slo2.1) from pXOOY to expression of these channels obtained from the reference vectors pEMBLyex4 and pXOOM. Our proof-of-concept study indicates that accumulation in PAP1500 yeast cells was higher when the channels were expressed from pXOOY, which was verified both qualitatively and quantitatively. Two-electrode voltage clamp measurements in oocytes showed that the pXOOY constructs encoding ohERG and ohSlick gave currents with full preservation of electrophysiological characteristics. Our results show that it is possible to design a dual-function Xenopus-yeast vector without compromising expression in yeast and simultaneously maintaining channel activity in oocytes.
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Affiliation(s)
- Victoria Amstrup Vold
- Department of Biology, University of Copenhagen, Copenhagen Ø, Denmark
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Sebastian Glanville
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Dan Arne Klaerke
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
- * E-mail: (PAP); (DAK)
| | - Per Amstrup Pedersen
- Department of Biology, University of Copenhagen, Copenhagen Ø, Denmark
- * E-mail: (PAP); (DAK)
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50
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Zangerl-Plessl EM, Wu W, Sanguinetti MC, Stary-Weinzinger A. Binding of RPR260243 at the intracellular side of the hERG1 channel pore domain slows closure of the helix bundle crossing gate. Front Mol Biosci 2023; 10:1137368. [PMID: 36911523 PMCID: PMC9996038 DOI: 10.3389/fmolb.2023.1137368] [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: 01/04/2023] [Accepted: 02/07/2023] [Indexed: 02/25/2023] Open
Abstract
The opening and closing of voltage-dependent potassium channels is dependent on a tight coupling between movement of the voltage sensing S4 segments and the activation gate. A specific interaction between intracellular amino- and carboxyl-termini is required for the characteristically slow rate of channel closure (deactivation) of hERG1 channels. Compounds that increase hERG1 channel currents represent a novel approach for prevention of arrhythmia associated with prolonged ventricular repolarization. RPR260243 (RPR), a quinoline oxo-propyl piperidine derivative, inhibits inactivation and dramatically slows the rate of hERG1 channel deactivation. Here we report that similar to its effect on wild-type channels, RPR greatly slows the deactivation rate of hERG1 channels missing their amino-termini, or of split channels lacking a covalent link between the voltage sensor domain and the pore domain. By contrast, RPR did not slow deactivation of C-terminal truncated hERG1 channels or D540K hERG1 mutant channels activated by hyperpolarization. Together, these findings indicate that ability of RPR to slow deactivation requires an intact C-terminus, does not slow deactivation by stabilizing an interaction involving the amino-terminus or require a covalent link between the voltage sensor and pore domains. All-atom molecular dynamics simulations using the cryo-EM structure of the hERG1 channel revealed that RPR binds to a pocket located at the intracellular ends of helices S5 and S6 of a single subunit. The slowing of channel deactivation by RPR may be mediated by disruption of normal S5-S6 interactions.
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Affiliation(s)
| | - Wei Wu
- Department of Internal Medicine, Nora Eccles Harrison Cardiovascular Research & Training Institute, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT, United States
| | - Michael C Sanguinetti
- 3 Department of Internal Medicine, Division of Cardiovascular Medicine, Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt LakeCity, UT, United States
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