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Fan W, Sun X, Yang C, Wan J, Luo H, Liao B. Pacemaker activity and ion channels in the sinoatrial node cells: MicroRNAs and arrhythmia. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 177:151-167. [PMID: 36450332 DOI: 10.1016/j.pbiomolbio.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 11/13/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
The primary pacemaking activity of the heart is determined by a spontaneous action potential (AP) within sinoatrial node (SAN) cells. This unique AP generation relies on two mechanisms: membrane clocks and calcium clocks. Nonhomologous arrhythmias are caused by several functional and structural changes in the myocardium. MicroRNAs (miRNAs) are essential regulators of gene expression in cardiomyocytes. These miRNAs play a vital role in regulating the stability of cardiac conduction and in the remodeling process that leads to arrhythmias. Although it remains unclear how miRNAs regulate the expression and function of ion channels in the heart, these regulatory mechanisms may support the development of emerging therapies. This study discusses the spread and generation of AP in the SAN as well as the regulation of miRNAs and individual ion channels. Arrhythmogenicity studies on ion channels will provide a research basis for miRNA modulation as a new therapeutic target.
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Affiliation(s)
- Wei Fan
- Department of Cardiovascular Surgery, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China
| | - Xuemei Sun
- Department of Pharmacy, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China
| | - Chao Yang
- Department of Cardiovascular Surgery, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China
| | - Juyi Wan
- Department of Cardiovascular Surgery, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China.
| | - Hongli Luo
- Department of Pharmacy, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China.
| | - Bin Liao
- Department of Cardiovascular Surgery, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China.
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TeBay C, McArthur JR, Mangala M, Kerr N, Heitmann S, Perry MD, Windley MJ, Vandenberg JI, Hill AP. Pathophysiological metabolic changes associated with disease modify the proarrhythmic risk profile of drugs with potential to prolong repolarisation. Br J Pharmacol 2021; 179:2631-2646. [PMID: 34837219 DOI: 10.1111/bph.15757] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 11/16/2021] [Accepted: 11/18/2021] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Hydroxychloroquine, chloroquine and azithromycin are three drugs that were proposed to treat COVID-19. While concern already existed around their proarrhythmic potential there is little data regarding how altered physiological states encountered in patients such as febrile state, electrolyte imbalances or acidosis might change their risk profiles. EXPERIMENTAL APPROACH Potency of hERG block was measured using high-throughput electrophysiology in the presence of variable environmental factors. These potencies informed simulations to predict population risk profiles. Effects on cardiac repolarisation were verified in human induced pluripotent stem cell-derived cardiomyocytes from multiple individuals. KEY RESULTS Chloroquine and hydroxychloroquine blocked hERG with IC50 of 1.47±0.07 μM and 3.78±0.17 μM respectively, indicating proarrhythmic risk at concentrations effective against SARS-CoV-2 in vitro. Hypokalaemia and hypermagnesemia increased potency of chloroquine and hydroxychloroquine, indicating increased proarrhythmic risk. Acidosis significantly reduced potency of all drugs, whereas increased temperature decreased potency of chloroquine and hydroxychloroquine against hERG but increased potency for azithromycin. In silico simulations demonstrated that proarrhythmic risk was increased by female sex, hypokalaemia and heart failure, and identified specific genetic backgrounds associated with emergence of arrhythmia. CONCLUSION AND IMPLICATIONS Our study demonstrates how proarrhythmic risk can be exacerbated by metabolic changes and pre-existing disease. More broadly, the study acts as a blueprint for how high-throughput in vitro screening, combined with in silico simulations can help guide both preclinical screening and clinical management of patients in relation to drugs with potential to prolong repolarisation.
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Affiliation(s)
- Clifford TeBay
- Victor Chang Cardiac Research Institute, Sydney, Australia
| | - Jeffrey R McArthur
- Victor Chang Cardiac Research Institute, Sydney, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Australia
| | - Melissa Mangala
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | - Nicholas Kerr
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | | | - Matthew D Perry
- Victor Chang Cardiac Research Institute, Sydney, Australia.,School of Medical Sciences, UNSW Sydney, Sydney, Australia
| | - Monique J Windley
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | - Adam P Hill
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
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Active Targeted Nanoemulsions for Repurposing of Tegaserod in Alzheimer's Disease Treatment. Pharmaceutics 2021; 13:pharmaceutics13101626. [PMID: 34683919 PMCID: PMC8540544 DOI: 10.3390/pharmaceutics13101626] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 09/29/2021] [Accepted: 10/01/2021] [Indexed: 12/13/2022] Open
Abstract
Background and Purpose: The activation of 5-HT4 receptors with agonists has emerged as a valuable therapeutic strategy to treat Alzheimer’s disease (AD) by enhancing the nonamyloidogenic pathway. Here, the potential therapeutic effects of tegaserod, an effective agent for irritable bowel syndrome, were assessed for AD treatment. To envisage its efficient repurposing, tegaserod-loaded nanoemulsions were developed and functionalized by a blood–brain barrier shuttle peptide. Results: The butyrylcholinesterase inhibitory activity of tegaserod and its neuroprotective cellular effects were highlighted, confirming the interest of this pleiotropic drug for AD treatment. In regard to its drugability profile, and in order to limit its peripheral distribution after IV administration, its encapsulation into monodisperse lipid nanoemulsions (Tg-NEs) of about 50 nm, and with neutral zeta potential characteristics, was performed. The stability of the formulation in stock conditions at 4 °C and in blood biomimetic medium was established. The adsorption on Tg-NEs of peptide-22 was realized. The functionalized NEs were characterized by chromatographic methods (SEC and C18/HPLC) and isothermal titration calorimetry, attesting the efficiency of the adsorption. From in vitro assays, these nanocarriers appeared suitable for enabling tegaserod controlled release without hemolytic properties. Conclusion: The developed peptide-22 functionalized Tg-NEs appear as a valuable tool to allow exploration of the repurposed tegaserod in AD treatment in further preclinical studies.
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Hosseini Z, Mollazadeh R, Dehghan-Manshadi SA, Mohebi M, Eslami M, Sadre-Bafghi SA, Akbari A, Ghodsi S. Association between exposure to Efavirenz and substrates of dysrhythmia in HIV-infected young adults. Clin Cardiol 2021; 44:1448-1456. [PMID: 34328227 PMCID: PMC8495077 DOI: 10.1002/clc.23705] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/09/2021] [Accepted: 07/13/2021] [Indexed: 11/15/2022] Open
Abstract
Background Dysrhythmia and sudden cardiac arrest occur more likely in HIV patients than healthy subjects. Thus, we need to examine dysrhythmias adverse effects of medications including Efavirenz as early as possible especially in young subjects. Hypothesis Efavirenz might have contributed to increased risk of developing common types of dysrhythmia in young HIV infected patients. Methods We performed a retrospective cohort study among 62 patients on Efavirenz and 38 controls. All participants were under 40 years old without cardiovascular disease. Total significant dysrhythmia in 24‐hour ECG monitoring was the primary endpoint determined as the composite of high premature ventricular contraction (PVC) (>500 beats per 24 hours), high premature atrial contraction (PAC) (>500 bp24h), sinus pause, atrioventricular blocks, ventricular tachycardia, prolonged QTc, and low heart rate variability (HRV). Modified composite dysrhythmia consisted of low HRV (SD of normal‐to‐normal [SDNN]), high PVC and prolonged QT. Results Mean heart rate, Efavirenz regimen, male gender, and CD4 count predicted total dysrhythmia. Odds ratios were 1.108, 2.90, 4.36, and 0.96, respectively. The incidence of total dysrhythmia, high PVC, high PAC, low HRV(SDNN), and prolonged QTc were 54.8%, 41.85%, 9.71%, 45.2%, and 12.9% in patients on Efavirenz against 42.11%, 31.64%, 0%, 34.2%, and 7.91% in controls, respectively (p‐values: .031, .001, <.0001, .063, and .043 respectively). Modified composite dysrhythmia was also more frequent in Efavirenz group than that of control group (69.42% vs. 52.60%, respectively p = .032). Conclusions We found that patients with Efavirenz had higher prevalence of frequent PVC, frequent PAC, total significant dysrhythmia, Low HRV and prolonged QTc than controls.
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Affiliation(s)
- Zahra Hosseini
- Department of Cardiology, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Mollazadeh
- Department of Cardiology, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed-Ali Dehghan-Manshadi
- Department of Infectious and Tropical diseases, HIV-AIDS Research Center, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehrnaz Mohebi
- Department of Research, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Masoud Eslami
- Department of Cardiology, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed-Ali Sadre-Bafghi
- Department of Research, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Ali Akbari
- Biomedical Engineering Hill-Rom (Mortara) Sale and Technical Expert, Iranbehdasht Co, Tehran, Iran
| | - Saeed Ghodsi
- Department of Cardiology, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
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Baracaldo-Santamaría D, Llinás-Caballero K, Corso-Ramirez JM, Restrepo CM, Dominguez-Dominguez CA, Fonseca-Mendoza DJ, Calderon-Ospina CA. Genetic and Molecular Aspects of Drug-Induced QT Interval Prolongation. Int J Mol Sci 2021; 22:8090. [PMID: 34360853 PMCID: PMC8347245 DOI: 10.3390/ijms22158090] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 07/04/2021] [Accepted: 07/06/2021] [Indexed: 12/22/2022] Open
Abstract
Long QT syndromes can be either acquired or congenital. Drugs are one of the many etiologies that may induce acquired long QT syndrome. In fact, many drugs frequently used in the clinical setting are a known risk factor for a prolonged QT interval, thus increasing the chances of developing torsade de pointes. The molecular mechanisms involved in the prolongation of the QT interval are common to most medications. However, there is considerable inter-individual variability in drug response, thus making the application of personalized medicine a relevant aspect in long QT syndrome, in order to evaluate the risk of every individual from a pharmacogenetic standpoint.
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Affiliation(s)
- Daniela Baracaldo-Santamaría
- School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia; (D.B.-S.); (J.M.C.-R.); (C.A.D.-D.)
| | - Kevin Llinás-Caballero
- GENIUROS Research Group, Center for Research in Genetics and Genomics (CIGGUR), School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia; (K.L.-C.); (C.M.R.); (D.J.F.-M.)
- Institute for Immunological Research, University of Cartagena, Cartagena 130014, Colombia
| | - Julián Miguel Corso-Ramirez
- School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia; (D.B.-S.); (J.M.C.-R.); (C.A.D.-D.)
| | - Carlos Martín Restrepo
- GENIUROS Research Group, Center for Research in Genetics and Genomics (CIGGUR), School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia; (K.L.-C.); (C.M.R.); (D.J.F.-M.)
| | | | - Dora Janeth Fonseca-Mendoza
- GENIUROS Research Group, Center for Research in Genetics and Genomics (CIGGUR), School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia; (K.L.-C.); (C.M.R.); (D.J.F.-M.)
| | - Carlos Alberto Calderon-Ospina
- GENIUROS Research Group, Center for Research in Genetics and Genomics (CIGGUR), School of Medicine and Health Sciences, Universidad del Rosario, Bogotá 111221, Colombia; (K.L.-C.); (C.M.R.); (D.J.F.-M.)
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Kozek K, Wada Y, Sala L, Denjoy I, Egly C, O'Neill MJ, Aiba T, Shimizu W, Makita N, Ishikawa T, Crotti L, Spazzolini C, Kotta MC, Dagradi F, Castelletti S, Pedrazzini M, Gnecchi M, Leenhardt A, Salem JE, Ohno S, Zuo Y, Glazer AM, Mosley JD, Roden DM, Knollmann BC, Blume JD, Extramiana F, Schwartz PJ, Horie M, Kroncke BM. Estimating the Posttest Probability of Long QT Syndrome Diagnosis for Rare KCNH2 Variants. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2021; 14:e003289. [PMID: 34309407 DOI: 10.1161/circgen.120.003289] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The proliferation of genetic profiling has revealed many associations between genetic variations and disease. However, large-scale phenotyping efforts in largely healthy populations, coupled with DNA sequencing, suggest variants currently annotated as pathogenic are more common in healthy populations than previously thought. In addition, novel and rare variants are frequently observed in genes associated with disease both in healthy individuals and those under suspicion of disease. This raises the question of whether these variants can be useful predictors of disease. To answer this question, we assessed the degree to which the presence of a variant in the cardiac potassium channel gene KCNH2 was diagnostically predictive for the autosomal dominant long QT syndrome. METHODS We estimated the probability of a long QT diagnosis given the presence of each KCNH2 variant using Bayesian methods that incorporated variant features such as changes in variant function, protein structure, and in silico predictions. We call this estimate the posttest probability of disease. Our method was applied to over 4000 individuals heterozygous for 871 missense or in-frame insertion/deletion variants in KCNH2 and validated against a separate international cohort of 933 individuals heterozygous for 266 missense or in-frame insertion/deletion variants. RESULTS Our method was well-calibrated for the observed fraction of heterozygotes diagnosed with long QT syndrome. Heuristically, we found that the innate diagnostic information one learns about a variant from 3-dimensional variant location, in vitro functional data, and in silico predictors is equivalent to the diagnostic information one learns about that same variant by clinically phenotyping 10 heterozygotes. Most importantly, these data can be obtained in the absence of any clinical observations. CONCLUSIONS We show how variant-specific features can inform a prior probability of disease for rare variants even in the absence of clinically phenotyped heterozygotes.
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Affiliation(s)
- Krystian Kozek
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | - Yuko Wada
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN.,Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan (Y.W., S.O., M.H.)
| | - Luca Sala
- Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano IRCCS, Cusano Milanino, Italy (L.S., L.C., C.K., M.P., P.J.S.)
| | - Isabelle Denjoy
- CNMR Maladies Cardiaques Héréditaires Rares, AP-HP, Hôpital Bichat, Paris, France (I.D., A.L., F.E.)
| | - Christian Egly
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | - Matthew J O'Neill
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | - Takeshi Aiba
- Department of Cardiovascular Medicine (T.A., N.M., S.O.), National Cerebral and Cardiovascular Center, Suita
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan (W.S.)
| | - Naomasa Makita
- Department of Cardiovascular Medicine (T.A., N.M., S.O.), National Cerebral and Cardiovascular Center, Suita.,7Omics Research Center (N.M., T.I.), National Cerebral and Cardiovascular Center, Suita
| | - Taisuke Ishikawa
- 7Omics Research Center (N.M., T.I.), National Cerebral and Cardiovascular Center, Suita
| | - Lia Crotti
- Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano IRCCS, Cusano Milanino, Italy (L.S., L.C., C.K., M.P., P.J.S.).,Department of Cardiovascular, Neural & Metabolic Sciences, San Luca Hospital (L.C.), Istituto Auxologico Italiano IRCCS.,Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS.,Department of Medicine and Surgery, University Milano Bicocca, Milan (L.C.)
| | - Carla Spazzolini
- Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS
| | | | - Federica Dagradi
- Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS
| | - Silvia Castelletti
- Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS
| | - Matteo Pedrazzini
- Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano IRCCS, Cusano Milanino, Italy (L.S., L.C., C.K., M.P., P.J.S.)
| | - Massimiliano Gnecchi
- Department of Molecular Medicine, Unit of Cardiology, University of Pavia (M.G.).,Intensive Cardiac Care Unit and Lab of Experimental Cardiology for Cell and Molecular Therapy, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy (M.G.)
| | - Antoine Leenhardt
- CNMR Maladies Cardiaques Héréditaires Rares, AP-HP, Hôpital Bichat, Paris, France (I.D., A.L., F.E.).,University de Paris (A.L., F.E.)
| | - Joe-Elie Salem
- Division of Cardiovascular Medicine, Cardio-oncology Program (J.-E.S.), Vanderbilt University Medical Center, Nashville, TN.,Sorbonne Université, INSERM CIC-1901, AP-HP, Department of Pharmacology, Regional Pharmacovigilance Center, Pitié-Salpêtrière Hospital, Paris, France (J.-E.S.)
| | - Seiko Ohno
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan (Y.W., S.O., M.H.).,Department of Cardiovascular Medicine (T.A., N.M., S.O.), National Cerebral and Cardiovascular Center, Suita
| | - Yi Zuo
- Department of Biostatistics (Y.Z., J.D.M., D.M.R.), Vanderbilt University, Nashville, TN
| | - Andrew M Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | - Jonathan D Mosley
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN.,Department of Biostatistics (Y.Z., J.D.M., D.M.R.), Vanderbilt University, Nashville, TN.,Biomedical Informatics (J.D.M.), Vanderbilt University, Nashville, TN
| | - Dan M Roden
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN.,Department of Biostatistics (Y.Z., J.D.M., D.M.R.), Vanderbilt University, Nashville, TN
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
| | | | - Fabrice Extramiana
- CNMR Maladies Cardiaques Héréditaires Rares, AP-HP, Hôpital Bichat, Paris, France (I.D., A.L., F.E.).,University de Paris (A.L., F.E.)
| | - Peter J Schwartz
- Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano IRCCS, Cusano Milanino, Italy (L.S., L.C., C.K., M.P., P.J.S.).,Center for Cardiac Arrhythmias of Genetic Origin (L.C., C.S., F.D., S.C., P.J.S.), Istituto Auxologico Italiano IRCCS
| | - Minoru Horie
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan (Y.W., S.O., M.H.)
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Departments of Medicine & Pharmacology (K.K., Y.W., C.E., M.J.O., A.M.G., J.D.M., D.M.R., B.C.K., B.M.K.), Vanderbilt University Medical Center, Nashville, TN
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7
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Exploring the inhibitory potentials of Momordica charantia bioactive compounds against Keap1-Kelch protein using computational approaches. In Silico Pharmacol 2021; 9:39. [PMID: 34249600 DOI: 10.1007/s40203-021-00100-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 06/22/2021] [Indexed: 12/11/2022] Open
Abstract
The search for Keap1 inhibitors as potential Nrf2 activator is a way of increasing the antioxidant status of the human cellular environ. In this research, we used in silico methods to investigate Keap1-kelch inhibitory potential of Momordica charantia's bioactive compounds in order to predict their Nrf2 activating potential. ADMET profiling, physicochemical properties, molecular docking, molecular dynamics, and Molecular Mechanics-Poisson Boltzmann Surface Area (g_MMPBSA) free energy calculation studies were executed to drive home our aim. Out of all the bioactive compounds of Momordica charantia, catechin (CAT) and chlorogenic acid (CGA) were selected based on their ADMET profile, physicochemical properties, and molecular docking analysis. Molecular docking studies of CAT and CGA to Keap1 kelch domain showed that they have - 9.2 kJ/mol and - 9.1 kJ/mol binding energies respectively with CAT having four hydrogen bond interactions with Keap1 while CGA had three. Analysis after the 30 ns molecular dynamics simulation revealed that CAT and CGA were both stable, although with minimal conformational alterations at the kelch pocket of Keap1. Finally, MMPBSA calculation of the Gibbs free energy of each amino acid interaction with CAT and CGA revealed that CAT had a higher total binding energy than CGA. Therefore, the Keap1 inhibitory capacities and the molecular dynamic characters of CAT and CGA at the Kelch domain of Keap1 suggest a putative Nrf2 signaling activating prowess. Supplementary Information The online version contains supplementary material available at 10.1007/s40203-021-00100-2.
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Colombian Scorpion Centruroides margaritatus: Purification and Characterization of a Gamma Potassium Toxin with Full-Block Activity on the hERG1 Channel. Toxins (Basel) 2021; 13:toxins13060407. [PMID: 34201318 PMCID: PMC8273696 DOI: 10.3390/toxins13060407] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 05/31/2021] [Accepted: 06/04/2021] [Indexed: 01/06/2023] Open
Abstract
The Colombian scorpion Centruroides margaritatus produces a venom considered of low toxicity. Nevertheless, there are known cases of envenomation resulting in cardiovascular disorders, probably due to venom components that target ion channels. Among them, the humanether-à-go-go-Related gene (hERG1) potassium channels are critical for cardiac action potential repolarization and alteration in its functionality are associated with cardiac disorders. This work describes the purification and electrophysiological characterization of a Centruroides margaritatus venom component acting on hERG1 channels, the CmERG1 toxin. This novel peptide is composed of 42 amino acids with a MW of 4792.88 Da, folded by four disulfide bonds and it is classified as member number 10 of the γ-KTx1 toxin family. CmERG1 inhibits hERG1 currents with an IC50 of 3.4 ± 0.2 nM. Despite its 90.5% identity with toxin ɣ-KTx1.1, isolated from Centruroides noxius, CmERG1 completely blocks hERG1 current, suggesting a more stable plug of the hERG channel, compared to that formed by other ɣ-KTx.
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9
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Szendrey M, Guo J, Li W, Yang T, Zhang S. COVID-19 Drugs Chloroquine and Hydroxychloroquine, but Not Azithromycin and Remdesivir, Block hERG Potassium Channels. J Pharmacol Exp Ther 2021; 377:265-272. [PMID: 33674391 DOI: 10.1124/jpet.120.000484] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/02/2021] [Indexed: 12/27/2022] Open
Abstract
Drug-induced long QT syndrome (LQTS) is an established cardiac side effect of a wide range of medications and represents a significant concern for drug safety. The rapidly and slowly activating delayed rectifier K+ currents, mediated by channels encoded by the human ether-a-go-go-related gene (hERG) and KCNQ1 + KCNE1, respectively, are two main currents responsible for ventricular repolarization. The common cause for drugs to induce LQTS is through impairing the hERG channel. For the recent emergence of COVID-19, caused by severe acute respiratory syndrome coronavirus 2, several drugs have been investigated as potential therapies; however, there are concerns about their QT prolongation risk. Here, we studied the effects of chloroquine, hydroxychloroquine, azithromycin, and remdesivir on hERG channels. Our results showed that although chloroquine acutely blocked hERG current (IhERG), with an IC50 of 3.0 µM, hydroxychloroquine acutely blocked IhERG 8-fold less potently, with an IC50 of 23.4 µM. Azithromycin and remdesivir did not acutely affect IhERG When these drugs were added at 10 µM to the cell culture medium for 24 hours, remdesivir increased IhERG by 2-fold, which was associated with an increased mature hERG channel expression. In addition, these four drugs did not acutely or chronically affect KCNQ1 + KCNE1 channels. Our data provide insight into COVID-19 drug-associated LQTS and cardiac safety concerns. SIGNIFICANCE STATEMENT: This work demonstrates that, among off-label potential COVID-19 treatment drugs chloroquine, hydroxychloroquine, azithromycin, and remdesivir, the former two drugs block hERG potassium channels, whereas the latter two drugs do not. All four drugs do not affect KCNQ1 + KCNE1. As hERG and KCNQ1 + KCNE1 are two main K+ channels responsible for ventricular repolarization, and most drugs that induce long QT syndrome (LQTS) do so by impairing hERG channels, these data provide insight into COVID-19 drug-associated LQTS and cardiac safety concerns.
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Affiliation(s)
- Mark Szendrey
- 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
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Berlansky S, Humer C, Sallinger M, Frischauf I. More Than Just Simple Interaction between STIM and Orai Proteins: CRAC Channel Function Enabled by a Network of Interactions with Regulatory Proteins. Int J Mol Sci 2021; 22:E471. [PMID: 33466526 PMCID: PMC7796502 DOI: 10.3390/ijms22010471] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 12/29/2020] [Accepted: 12/29/2020] [Indexed: 12/27/2022] Open
Abstract
The calcium-release-activated calcium (CRAC) channel, activated by the release of Ca2+ from the endoplasmic reticulum (ER), is critical for Ca2+ homeostasis and active signal transduction in a plethora of cell types. Spurred by the long-sought decryption of the molecular nature of the CRAC channel, considerable scientific effort has been devoted to gaining insights into functional and structural mechanisms underlying this signalling cascade. Key players in CRAC channel function are the Stromal interaction molecule 1 (STIM1) and Orai1. STIM1 proteins span through the membrane of the ER, are competent in sensing luminal Ca2+ concentration, and in turn, are responsible for relaying the signal of Ca2+ store-depletion to pore-forming Orai1 proteins in the plasma membrane. A direct interaction of STIM1 and Orai1 allows for the re-entry of Ca2+ from the extracellular space. Although much is already known about the structure, function, and interaction of STIM1 and Orai1, there is growing evidence that CRAC under physiological conditions is dependent on additional proteins to function properly. Several auxiliary proteins have been shown to regulate CRAC channel activity by means of direct interactions with STIM1 and/or Orai1, promoting or hindering Ca2+ influx in a mechanistically diverse manner. Various proteins have also been identified to exert a modulatory role on the CRAC signalling cascade although inherently lacking an affinity for both STIM1 and Orai1. Apart from ubiquitously expressed representatives, a subset of such regulatory mechanisms seems to allow for a cell-type-specific control of CRAC channel function, considering the rather restricted expression patterns of the specific proteins. Given the high functional and clinical relevance of both generic and cell-type-specific interacting networks, the following review shall provide a comprehensive summary of regulators of the multilayered CRAC channel signalling cascade. It also includes proteins expressed in a narrow spectrum of cells and tissues that are often disregarded in other reviews of similar topics.
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Affiliation(s)
| | | | | | - Irene Frischauf
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, Austria; (S.B.); (C.H.); (M.S.)
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Moolman C, van der Sluis R, Beteck RM, Legoabe LJ. An Update on Development of Small-Molecule Plasmodial Kinase Inhibitors. Molecules 2020; 25:E5182. [PMID: 33171706 PMCID: PMC7664427 DOI: 10.3390/molecules25215182] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 12/21/2022] Open
Abstract
Malaria control relies heavily on the small number of existing antimalarial drugs. However, recurring antimalarial drug resistance necessitates the continual generation of new antimalarial drugs with novel modes of action. In order to shift the focus from only controlling this disease towards elimination and eradication, next-generation antimalarial agents need to address the gaps in the malaria drug arsenal. This includes developing drugs for chemoprotection, treating severe malaria and blocking transmission. Plasmodial kinases are promising targets for next-generation antimalarial drug development as they mediate critical cellular processes and some are active across multiple stages of the parasite's life cycle. This review gives an update on the progress made thus far with regards to plasmodial kinase small-molecule inhibitor development.
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Affiliation(s)
- Chantalle Moolman
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa; (C.M.); (R.M.B.)
| | - Rencia van der Sluis
- Focus Area for Human Metabolomics, Biochemistry, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa;
| | - Richard M. Beteck
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa; (C.M.); (R.M.B.)
| | - Lesetja J. Legoabe
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa; (C.M.); (R.M.B.)
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12
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Hsiao Y, Su BH, Tseng YJ. Current development of integrated web servers for preclinical safety and pharmacokinetics assessments in drug development. Brief Bioinform 2020; 22:5881374. [PMID: 32770190 DOI: 10.1093/bib/bbaa160] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/22/2020] [Accepted: 06/24/2020] [Indexed: 12/27/2022] Open
Abstract
In drug development, preclinical safety and pharmacokinetics assessments of candidate drugs to ensure the safety profile are a must. While in vivo and in vitro tests are traditionally used, experimental determinations have disadvantages, as they are usually time-consuming and costly. In silico predictions of these preclinical endpoints have each been developed in the past decades. However, only a few web-based tools have integrated different models to provide a simple one-step platform to help researchers thoroughly evaluate potential drug candidates. To efficiently achieve this approach, a platform for preclinical evaluation must not only predict key ADMET (absorption, distribution, metabolism, excretion and toxicity) properties but also provide some guidance on structural modifications to improve the undesired properties. In this review, we organized and compared several existing integrated web servers that can be adopted in preclinical drug development projects to evaluate the subject of interest. We also introduced our new web server, Virtual Rat, as an alternative choice to profile the properties of drug candidates. In Virtual Rat, we provide not only predictions of important ADMET properties but also possible reasons as to why the model made those structural predictions. Multiple models were implemented into Virtual Rat, including models for predicting human ether-a-go-go-related gene (hERG) inhibition, cytochrome P450 (CYP) inhibition, mutagenicity (Ames test), blood-brain barrier penetration, cytotoxicity and Caco-2 permeability. Virtual Rat is free and has been made publicly available at https://virtualrat.cmdm.tw/.
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Boldrini-França J, Pinheiro-Junior EL, Peigneur S, Pucca MB, Cerni FA, Borges RJ, Costa TR, Carone SEI, Fontes MRDM, Sampaio SV, Arantes EC, Tytgat J. Beyond hemostasis: a snake venom serine protease with potassium channel blocking and potential antitumor activities. Sci Rep 2020; 10:4476. [PMID: 32161292 PMCID: PMC7066243 DOI: 10.1038/s41598-020-61258-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 02/19/2020] [Indexed: 02/07/2023] Open
Abstract
Snake venom serine proteases (SVSPs) are complex and multifunctional enzymes, acting primarily on hemostasis. In this work, we report the hitherto unknown inhibitory effect of a SVSP, named collinein-1, isolated from the venom of Crotalus durissus collilineatus, on a cancer-relevant voltage-gated potassium channel (hEAG1). Among 12 voltage-gated ion channels tested, collinein-1 selectively inhibited hEAG1 currents, with a mechanism independent of its enzymatic activity. Corroboratively, we demonstrated that collinein-1 reduced the viability of human breast cancer cell line MCF7 (high expression of hEAG1), but does not affect the liver carcinoma and the non-tumorigenic epithelial breast cell lines (HepG2 and MCF10A, respectively), which present low expression of hEAG1. In order to obtain both functional and structural validation of this unexpected discovery, where an unusually large ligand acts as an inhibitor of an ion channel, a recombinant and catalytically inactive mutant of collinein-1 (His43Arg) was produced and found to preserve its capability to inhibit hEAG1. A molecular docking model was proposed in which Arg79 of the SVSP 99-loop interacts directly with the potassium selectivity filter of the hEAG1 channel.
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Affiliation(s)
- Johara Boldrini-França
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café s/n°, 14040-903, Ribeirão Preto, SP, Brazil.,University of Vila Velha, Av. Comissário José Dantas de Melo, 21, Boa Vista II, 29102-920, Vila Velha, ES, Brazil
| | - Ernesto Lopes Pinheiro-Junior
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café s/n°, 14040-903, Ribeirão Preto, SP, Brazil.,Toxicology and Pharmacology, KU Leuven, O&N II Herestraat 49, PO 922, 3000, Leuven, Belgium
| | - Steve Peigneur
- Toxicology and Pharmacology, KU Leuven, O&N II Herestraat 49, PO 922, 3000, Leuven, Belgium
| | - Manuela Berto Pucca
- Medical School of Roraima, Federal University of Roraima, Av. Capitão Ene Garcez, 2413, Bairro Aeroporto, 69310-970, Boa Vista, RR, Brazil
| | - Felipe Augusto Cerni
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café s/n°, 14040-903, Ribeirão Preto, SP, Brazil
| | - Rafael Junqueira Borges
- Institute of Biosciences, São Paulo State University (UNESP), Rua Prof. Dr. Antonio Celso Wagner Zanin, 250, 18618-689, Botucatu, SP, Brazil
| | - Tássia Rafaella Costa
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café s/n°, 14040-903, Ribeirão Preto, SP, Brazil
| | - Sante Emmanuel Imai Carone
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café s/n°, 14040-903, Ribeirão Preto, SP, Brazil
| | - Marcos Roberto de Mattos Fontes
- Institute of Biosciences, São Paulo State University (UNESP), Rua Prof. Dr. Antonio Celso Wagner Zanin, 250, 18618-689, Botucatu, SP, Brazil
| | - Suely Vilela Sampaio
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café s/n°, 14040-903, Ribeirão Preto, SP, Brazil
| | - Eliane Candiani Arantes
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café s/n°, 14040-903, Ribeirão Preto, SP, Brazil.
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, O&N II Herestraat 49, PO 922, 3000, Leuven, Belgium.
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Iorio J, Petroni G, Duranti C, Lastraioli E. Potassium and Sodium Channels and the Warburg Effect: Biophysical Regulation of Cancer Metabolism. Bioelectricity 2019; 1:188-200. [PMID: 34471821 PMCID: PMC8370285 DOI: 10.1089/bioe.2019.0017] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Ion channels are progressively emerging as a novel class of membrane proteins expressed in several types of human cancers and regulating the different aspects of cancer cell behavior. The metabolism of cancer cells, usually composed by a variable proportion of respiration, glycolysis, and glutaminolysis, leads to the excessive production of acidic metabolic products. The presence of these acidic metabolites inside the cells results in intracellular acidosis, and hinders survival and proliferation. For this reason, tumor cells activate mechanisms of pH control that produce a constitutive increase in intracellular pH (pHi) that is more acidic than the extracellular pH (pHe). This condition forms a perfect microenvironment for metastatic progression and may be permissive for some of the acquired characteristics of tumors. Recent analyses have revealed complex interconnections between oncogenic activation, ion channels, hypoxia signaling and metabolic pathways that are dysregulated in cancer. Here, we summarize the molecular mechanisms of the Warburg effect and hypoxia and their association. Moreover, we discuss the recent findings concerning the involvement of ion channels in various aspects of the Warburg effect and hypoxia, focusing on the role of Na+ and K+ channels in hypoxic and metabolic reprogramming in cancer.
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Affiliation(s)
- Jessica Iorio
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Giulia Petroni
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Claudia Duranti
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Elena Lastraioli
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
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15
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Di Stolfo G, Accadia M, Mastroianno S, Leone MP, Palumbo O, Palumbo P, Potenza D, Maccarone P, Sacco M, Russo A, Carella M. Long QT syndrome in chromosome 7q35q36.3 deletion involving KCNH2 gene: Warning for chlorpheniramine prescription. Mol Genet Genomic Med 2019; 7:e855. [PMID: 31347270 PMCID: PMC6732270 DOI: 10.1002/mgg3.855] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 05/12/2019] [Accepted: 06/17/2019] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The deletion of the distal 7q region is a rare chromosomal syndrome characterized by wide phenotypic manifestations including growth and psychomotor delay, facial dysmorphisms, and genitourinary malformations. METHODS We describe a 6-year-old child with a 12-Mb deletion of the region 7q35q36.3. RESULTS Among the deleted genes, two genes have cardiac implications: PRKAG2 (OMIM #602743), associated with hypertrophic cardiomyopathy, cardiac conduction disease, and sudden death, and KCNH2 (OMIM #152427), coding for a cardiac potassium channel involved in long QT syndrome, unmasked by the chlorpheniramine treatment. At same time, the SHH gene (OMIM #600725), encoding sonic hedgehog, a secreted protein that is involved in the embryonic development, is deleted. CONCLUSION Our report underlines potential cardiac complications linked to the common pharmacological treatment in this rare multiorgan and proteiform disease.
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Affiliation(s)
- Giuseppe Di Stolfo
- Cardiovascular Department, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Maria Accadia
- Medical Genetics Service, Hospital "Cardinale G. Panico", Tricase, Lecce, Italy
| | - Sandra Mastroianno
- Cardiovascular Department, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Maria P Leone
- Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Orazio Palumbo
- Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Pietro Palumbo
- Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Domenico Potenza
- Cardiovascular Department, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Pasquale Maccarone
- Paediatric Unit, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Michele Sacco
- Paediatric Unit, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Aldo Russo
- Cardiovascular Department, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Massimo Carella
- Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
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16
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Sahli Costabal F, Yao J, Sher A, Kuhl E. Predicting critical drug concentrations and torsadogenic risk using a multiscale exposure-response simulator. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 144:61-76. [PMID: 30482568 PMCID: PMC6483901 DOI: 10.1016/j.pbiomolbio.2018.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 09/21/2018] [Accepted: 10/11/2018] [Indexed: 12/12/2022]
Abstract
Torsades de pointes is a serious side effect of many drugs that can trigger sudden cardiac death, even in patients with structurally normal hearts. Torsadogenic risk has traditionally been correlated with the blockage of a specific potassium channel and a prolonged recovery period in the electrocardiogram. However, the precise mechanisms by which single channel block translates into heart rhythm disorders remain incompletely understood. Here we establish a multiscale exposure-response simulator that converts block-concentration characteristics from single cell recordings into three-dimensional excitation profiles and electrocardiograms to rapidly assess torsadogenic risk. For the drug dofetilide, we characterize the QT interval and heart rate at different drug concentrations and identify the critical concentration at the onset of torsades de pointes: For dofetilide concentrations of 2x, 3x, and 4x, as multiples of the free plasma concentration Cmax = 2.1 nM, the QT interval increased by +62.0%, +71.2%, and +82.3% compared to baseline, and the heart rate changed by -21.7%, -23.3%, and +88.3%. The last number indicates that, at the critical concentration of 4x, the heart spontaneously developed an episode of a torsades-like arrhythmia. Strikingly, this critical drug concentration is higher than the concentration estimated from early afterdepolarizations in single cells and lower than in one-dimensional cable models. Our results highlight the importance of whole heart modeling and explain, at least in part, why current regulatory paradigms often fail to accurately quantify the pro-arrhythmic potential of a drug. Our exposure-response simulator could provide a more mechanistic assessment of pro-arrhythmic risk and help establish science-based guidelines to reduce rhythm disorders, design safer drugs, and accelerate drug development.
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Affiliation(s)
| | - Jiang Yao
- Dassault Systèmes Simulia Corporation, Johnston, RI, 02919, United States
| | - Anna Sher
- Internal Medicine Research Unit, Pfizer Inc, Cambridge, MA, 02139, United States
| | - Ellen Kuhl
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, United States.
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Zhang X, Liu T, Li Q, Li M, Du L. Aggregation-Induced Emission: Lighting Up hERG Potassium Channel. Front Chem 2019; 7:54. [PMID: 30800649 PMCID: PMC6375833 DOI: 10.3389/fchem.2019.00054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 01/21/2019] [Indexed: 11/13/2022] Open
Abstract
Based on the scaffold of astemizole and E-4031, four AIE light-up probes (L1-L4) for Human Ether-a-go-go-Related Gene (hERG) potassium channel were developed herein using AIE fluorogen(TPE). These probes showing advantages such as low background interference, superior photostability, acceptable cell toxicity, and potent inhibitory activity, which could be used to image hERG channels at the nanomolar level. These AIE light-up probes hoped to provide guidelines for the design of more advanced AIE sensing and imaging hERG channels to a broad range of applications.
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Affiliation(s)
- Xiaomeng Zhang
- Key Laboratory of Chemical Biology (MOE), Department of Medicinal Chemistry, School of Pharmacy, Shandong University, Jinan, China
| | - Tingting Liu
- Key Laboratory of Chemical Biology (MOE), Department of Medicinal Chemistry, School of Pharmacy, Shandong University, Jinan, China
| | - Qi Li
- Key Laboratory of Chemical Biology (MOE), Department of Medicinal Chemistry, School of Pharmacy, Shandong University, Jinan, China
| | - Minyong Li
- Key Laboratory of Chemical Biology (MOE), Department of Medicinal Chemistry, School of Pharmacy, Shandong University, Jinan, China
| | - Lupei Du
- Key Laboratory of Chemical Biology (MOE), Department of Medicinal Chemistry, School of Pharmacy, Shandong University, Jinan, China
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18
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Lee W, Windley MJ, Perry MD, Vandenberg JI, Hill AP. Protocol-Dependent Differences in IC 50 Values Measured in Human Ether-Á-Go-Go-Related Gene Assays Occur in a Predictable Way and Can Be Used to Quantify State Preference of Drug Binding. Mol Pharmacol 2019; 95:537-550. [PMID: 30770456 DOI: 10.1124/mol.118.115220] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 02/10/2019] [Indexed: 12/22/2022] Open
Abstract
Current guidelines around preclinical screening for drug-induced arrhythmias require the measurement of the potency of block of voltage-gated potassium channel subtype 11.1 (Kv11.1) as a surrogate for risk. A shortcoming of this approach is that the measured IC50 of Kv11.1 block varies widely depending on the voltage protocol used in electrophysiological assays. In this study, we aimed to investigate the factors that contribute to these differences and to identify whether it is possible to make predictions about protocol-dependent block that might facilitate the comparison of potencies measured using different assays. Our data demonstrate that state preferential binding, together with drug-binding kinetics and trapping, is an important determinant of the protocol dependence of Kv11.1 block. We show for the first time that differences in IC50 measured between protocols occurs in a predictable way, such that machine-learning algorithms trained using a selection of simple voltage protocols can indeed predict protocol-dependent potency. Furthermore, we also show that the preference of a drug for binding to the open versus the inactivated state of Kv11.1 can also be inferred from differences in IC50 values measured between protocols. Our work therefore identifies how state preferential drug binding is a major determinant of the protocol dependence of IC50 values measured in preclinical Kv11.1 assays. It also provides a novel method for quantifying the state dependence of Kv11.1 drug binding that will facilitate the development of more complete models of drug binding to Kv11.1 and improve our understanding of proarrhythmic risk associated with compounds that block Kv11.1.
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Affiliation(s)
- William Lee
- Victor Chang Cardiac Research Institute (W.L., M.J.W., M.D.P., J.I.V., A.P.H.) and St Vincent's Clinical School (W.L., M.J.W., M.D.P., J.I.V., A.P.H.), University of New South Wales, Darlinghurst, New South Wales, Australia
| | - Monique J Windley
- Victor Chang Cardiac Research Institute (W.L., M.J.W., M.D.P., J.I.V., A.P.H.) and St Vincent's Clinical School (W.L., M.J.W., M.D.P., J.I.V., A.P.H.), University of New South Wales, Darlinghurst, New South Wales, Australia
| | - Matthew D Perry
- Victor Chang Cardiac Research Institute (W.L., M.J.W., M.D.P., J.I.V., A.P.H.) and St Vincent's Clinical School (W.L., M.J.W., M.D.P., J.I.V., A.P.H.), University of New South Wales, Darlinghurst, New South Wales, Australia
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute (W.L., M.J.W., M.D.P., J.I.V., A.P.H.) and St Vincent's Clinical School (W.L., M.J.W., M.D.P., J.I.V., A.P.H.), University of New South Wales, Darlinghurst, New South Wales, Australia
| | - Adam P Hill
- Victor Chang Cardiac Research Institute (W.L., M.J.W., M.D.P., J.I.V., A.P.H.) and St Vincent's Clinical School (W.L., M.J.W., M.D.P., J.I.V., A.P.H.), University of New South Wales, Darlinghurst, New South Wales, Australia
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A Randomized Trial to Assess the Effect of Doravirine on the QTc Interval Using a Single Supratherapeutic Dose in Healthy Adult Volunteers. Clin Drug Investig 2018; 37:975-984. [PMID: 28785879 DOI: 10.1007/s40261-017-0552-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Doravirine is a novel HIV-1 non-nucleoside reverse transcriptase inhibitor exhibiting a robust safety and efficacy profile in combination with other antiretrovirals. While existing data do not suggest that doravirine delays cardiac repolarization, the aim of this trial was to evaluate the effects of a supratherapeutic dose of doravirine on the heart-rate corrected QT (QTc) interval in healthy adults. METHODS A randomized, three-period, crossover, placebo-controlled trial was conducted in healthy adults, 18-55 years of age. Three treatments were administered: single-dose doravirine 1200 mg, placebo, and positive control (single-dose moxifloxacin 400 mg). QT interval measurements were collected at serial time points following treatment administration. Clinically significant placebo-corrected, baseline-adjusted QTc interval prolongation was defined when the upper bound of the two-sided 90% confidence interval (CI) for the mean effect on double delta QTc exceeded 10 ms. Doravirine tolerability and pharmacokinetics were also evaluated. RESULTS Forty-five subjects were enrolled and 39 completed the study per protocol. Fridericia's QT correction for heart rate was demonstrated to be inadequate; therefore, a population-specific correction was applied (QTcP). Assay sensitivity was confirmed with moxifloxacin. Following doravirine administration, QTc intervals did not exceed the pre-specified significance threshold - upper 90% CIs were ≤5.42 ms across all time points. Categorical analyses identified no outliers or clinically meaningful deviations. Doravirine geometric mean area under the time-concentration curve from dosing until 24 h post-dose (AUC0-24) and maximum plasma concentration (C max) were 119 µM·h and 9240 nM, respectively, which exceeded values expected following therapeutic dose administration of doravirine 100 mg, even in the setting of intrinsic and extrinsic factors that may cause increases in doravirine concentrations. All treatments were generally well tolerated. CONCLUSION A single oral supratherapeutic dose of doravirine 1200 mg does not cause clinically meaningful QTc interval prolongation in healthy adults.
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Lee W, Windley MJ, Vandenberg JI, Hill AP. In Vitro and In Silico Risk Assessment in Acquired Long QT Syndrome: The Devil Is in the Details. Front Physiol 2017; 8:934. [PMID: 29201009 PMCID: PMC5696636 DOI: 10.3389/fphys.2017.00934] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 11/03/2017] [Indexed: 12/16/2022] Open
Abstract
Acquired long QT syndrome, mostly as a result of drug block of the Kv11. 1 potassium channel in the heart, is characterized by delayed cardiac myocyte repolarization, prolongation of the T interval on the ECG, syncope and sudden cardiac death due to the polymorphic ventricular arrhythmia Torsade de Pointes (TdP). In recent years, efforts are underway through the Comprehensive in vitro proarrhythmic assay (CiPA) initiative, to develop better tests for this drug induced arrhythmia based in part on in silico simulations of pharmacological disruption of repolarization. However, drug binding to Kv11.1 is more complex than a simple binary molecular reaction, meaning simple steady state measures of potency are poor surrogates for risk. As a result, there is a plethora of mechanistic detail describing the drug/Kv11.1 interaction—such as drug binding kinetics, state preference, temperature dependence and trapping—that needs to be considered when developing in silico models for risk prediction. In addition to this, other factors, such as multichannel pharmacological profile and the nature of the ventricular cell models used in simulations also need to be considered in the search for the optimum in silico approach. Here we consider how much of mechanistic detail needs to be included for in silico models to accurately predict risk and further, how much of this detail can be retrieved from protocols that are practical to implement in high throughout screens as part of next generation of preclinical in silico drug screening approaches?
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Affiliation(s)
- William Lee
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Monique J Windley
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Jamie I Vandenberg
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Adam P Hill
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
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21
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Papp R, Bett GCL, Lis A, Rasmusson RL, Baczkó I, Varró A, Salama G. Genomic upregulation of cardiac Cav1.2α and NCX1 by estrogen in women. Biol Sex Differ 2017; 8:26. [PMID: 28807015 PMCID: PMC5557418 DOI: 10.1186/s13293-017-0148-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 08/04/2017] [Indexed: 01/08/2023] Open
Abstract
Background Women have a higher risk of lethal arrhythmias than men in long QT syndrome type 2 (LQTS2), but the mechanisms remain uncertain due to the limited availability of healthy control human tissue. We have previously reported that in female rabbits, estrogen increases arrhythmia risk in drug-induced LQTS2 by upregulating L-type Ca2+ (ICa,L) and sodium-calcium exchange (INCX) currents at the base of the epicardium by a genomic mechanism. This study investigates if the effects of estrogen on rabbit ICa,L and INCX apply to human hearts. Methods Postmortem human left ventricular tissue samples were probed with selective antibodies for regional heterogeneities of ion channel protein expression and compared to rabbit myocardium. Functionally, ICa,L and INCX were measured from female and male cardiomyocytes derived from human induced pluripotent stem cells (iPS-CMs) with the voltage-clamp technique from control and estrogen-treated iPS-CMs. Results In women (n = 12), Cav1.2α (primary subunit of the L-type calcium channel protein 1) and NCX1 (sodium-calcium exchange protein) levels were higher at the base than apex of the epicardium (40 ± 14 and 81 ± 30%, respectively, P < 0.05), but not in men (n = 6) or postmenopausal women (n = 6). Similarly, in cardiomyocytes derived from female human iPS-CMs, estrogen (1 nM, 1–2 days) increased ICa,L (31%, P < 0.05) and INCX (7.5-fold, − 90 mV, P < 0.01) and their mRNA levels (P < 0.05). Moreover, in male human iPS-CMs, estrogen failed to alter ICa,L and INCX. Conclusions The results show that estrogen upregulates cardiac ICa,L and INCX in women through genomic mechanisms that account for sex differences in Ca2+ handling and spatial heterogeneities of repolarization due to base-apex heterogeneities of Cav1.2α and NCX1. By analogy with rabbit studies, these effects account for human sex-difference in arrhythmia risk.
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Affiliation(s)
- Rita Papp
- Department of Bioengineering and the Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, PA, 15261, USA.,Current Address: Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria
| | - Glenna C L Bett
- Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA.,Department of Physiology and Biophysics, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA.,Obstetrics-Gynecology, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA
| | - Agnieszka Lis
- Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA.,Department of Physiology and Biophysics, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA
| | - Randall L Rasmusson
- Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA.,Department of Physiology and Biophysics, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.,MTA-SZTE Research Group for Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Guy Salama
- Department of Bioengineering and the Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, PA, 15261, USA. .,Department of Bioengineering and the Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, 3550 Terrace Street, S628 Scaife Hall, Pittsburgh, PA, 15261, USA.
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22
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Hu D, Li Y, Zhang J, Pfeiffer R, Gollob MH, Healey J, Harrell DT, Makita N, Abe H, Sun Y, Guo J, Zhang L, Yan G, Mah D, Walsh EP, Leopold HB, Giustetto C, Gaita F, Zienciuk-Krajka A, Mazzanti A, Priori SG, Antzelevitch C, Barajas-Martinez H. The Phenotypic Spectrum of a Mutation Hotspot Responsible for the Short QT Syndrome. JACC Clin Electrophysiol 2017; 3:727-743. [DOI: 10.1016/j.jacep.2016.11.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 11/18/2016] [Accepted: 11/22/2016] [Indexed: 10/20/2022]
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23
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Durdagi S, Erol I, Salmas RE, Patterson M, Noskov SY. First universal pharmacophore model for hERG1 K + channel activators: acthER. J Mol Graph Model 2017; 74:153-170. [PMID: 28499268 DOI: 10.1016/j.jmgm.2017.03.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 01/31/2023]
Abstract
The intra-cavitary drug blockade of hERG1 channel has been extensively studied, both experimentally and theoretically. Structurally diverse ligands inadvertently block the hERG1 K+ channel currents lead to drug induced Long QT Syndrome (LQTS). Accordingly, designing either hERG1 channel openers or current activators, with the potential to target other binding pockets of the channel, has been introduced as a viable approach in modern anti-arrhythmia drug development. However, reports and investigations on the molecular mechanisms underlying activators binding to the hERG1 channel remain sparse and the overall molecular design principles are largely unknown. Most of the hERG1 activators were discovered during mandatory screening for hERG1 blockade. To fill this apparent deficit, the first universal pharmacophore model for hERG1 K+ channel activators was developed using PHASE. 3D structures of 18 hERG1 K+ channel activators and their corresponding measured binding affinity values were used in the development of pharmacophore models. These compounds spanned a range of structurally different chemotypes with moderate variation in binding affinity. A five sites AAHRR (A, hydrogen-bond accepting, H, hydrophobic, R, aromatic) pharmacophore model has shown reasonable high statistical results compared to the other developed more than 1000 hypotheses. This model was used to construct steric and electrostatic contour maps. The predictive power of the model was tested with 3 external test set compounds as true unknowns. Finally, the pharmacophore model was combined with the previously developed receptor-based model of hERG1 K+ channel to develop and screen novel activators. The results are quite striking and it suggests a greater future role for pharmacophore modeling and virtual drug screening simulations in deciphering complex patterns of molecular mechanisms of hERG1 channel openers at the target sites. The developed model is available upon request and it may serve as basis for the synthesis of novel therapeutic hERG1 activators.
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Affiliation(s)
- Serdar Durdagi
- Computational Biology and Molecular Simulations Laboratory, Department of Biophysics, School of Medicine, Bahcesehir University, Istanbul, Turkey.
| | - Ismail Erol
- Computational Biology and Molecular Simulations Laboratory, Department of Biophysics, School of Medicine, Bahcesehir University, Istanbul, Turkey; Department of Chemistry, Gebze Technical University, Kocaeli, Turkey
| | - Ramin Ekhteiari Salmas
- Computational Biology and Molecular Simulations Laboratory, Department of Biophysics, School of Medicine, Bahcesehir University, Istanbul, Turkey
| | - Matthew Patterson
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Sergei Y Noskov
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
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24
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Ek WE, Ahsan M, Rask-Andersen M, Liang L, Moffatt MF, Gyllensten U, Johansson Å. Epigenome-wide DNA methylation study of IgE concentration in relation to self-reported allergies. Epigenomics 2017; 9:407-418. [PMID: 28322575 DOI: 10.2217/epi-2016-0158] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
AIM Epigenetic mechanisms are critical for normal immune development and epigenetic alterations might therefore be possible contributors to immune diseases. To investigate if DNA methylation in whole blood is associated with total and allergen-specific IgE levels. METHODS We performed an epigenome-wide association study to investigate the association between DNA methylation and IgE level, allergen-specific IgE and self-reported immune diseases and allergies in 728 individuals. RESULTS We identified and replicated 15 CpG sites associated with IgE, mapping to biologically relevant genes, including ACOT7, ILR5A, KCNH2, PRG2 and EPX. A total of 331 loci were associated with allergen-specific IgE, but none of these CpG sites were associated with self-reported allergies and immune diseases. CONCLUSION This study shows that IgE levels are associated with DNA methylation levels at numerous CpG sites, which might provide new leads for investigating the links between IgE and allergic inflammation.
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Affiliation(s)
- Weronica E Ek
- Department of Immunology, Genetics & Pathology, Science for Life Laboratory, Uppsala University, Box 815 75108 Uppsala, Sweden
| | - Muhammad Ahsan
- Department of Immunology, Genetics & Pathology, Science for Life Laboratory, Uppsala University, Box 815 75108 Uppsala, Sweden
| | - Mathias Rask-Andersen
- Department of Immunology, Genetics & Pathology, Science for Life Laboratory, Uppsala University, Box 815 75108 Uppsala, Sweden
| | - Liming Liang
- Department of Epidemiology & Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA
| | - Miriam F Moffatt
- National Heart & Lung Institute, Imperial College London, London, SW3 6LY, UK
| | - Ulf Gyllensten
- Department of Immunology, Genetics & Pathology, Science for Life Laboratory, Uppsala University, Box 815 75108 Uppsala, Sweden
| | - Åsa Johansson
- Department of Immunology, Genetics & Pathology, Science for Life Laboratory, Uppsala University, Box 815 75108 Uppsala, Sweden
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25
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Hill AP, Perry MD, Abi-Gerges N, Couderc JP, Fermini B, Hancox JC, Knollmann BC, Mirams GR, Skinner J, Zareba W, Vandenberg JI. Computational cardiology and risk stratification for sudden cardiac death: one of the grand challenges for cardiology in the 21st century. J Physiol 2016; 594:6893-6908. [PMID: 27060987 PMCID: PMC5134408 DOI: 10.1113/jp272015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/16/2016] [Indexed: 12/25/2022] Open
Abstract
Risk stratification in the context of sudden cardiac death has been acknowledged as one of the major challenges facing cardiology for the past four decades. In recent years, the advent of high performance computing has facilitated organ-level simulation of the heart, meaning we can now examine the causes, mechanisms and impact of cardiac dysfunction in silico. As a result, computational cardiology, largely driven by the Physiome project, now stands at the threshold of clinical utility in regards to risk stratification and treatment of patients at risk of sudden cardiac death. In this white paper, we outline a roadmap of what needs to be done to make this translational step, using the relatively well-developed case of acquired or drug-induced long QT syndrome as an exemplar case.
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Affiliation(s)
- Adam P Hill
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia.,St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Matthew D Perry
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia.,St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Najah Abi-Gerges
- AnaBios Corporation, 3030 Bunker Hill St., San Diego, CA, 92109, USA
| | | | - Bernard Fermini
- Global Safety Pharmacology, Pfizer Inc, MS8274-1347 Eastern Point Road, Groton, CT, 06340, USA
| | - Jules C Hancox
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Bjorn C Knollmann
- Vanderbilt University School of Medicine, 1285 Medical Research Building IV, Nashville, Tennessee, 37232, USA
| | - Gary R Mirams
- Computational Biology, Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Jon Skinner
- Cardiac Inherited Disease Group, Starship Hospital, Auckland, New Zealand
| | - Wojciech Zareba
- University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia.,St. Vincent's Clinical School, University of New South Wales, Sydney, NSW, 2052, Australia
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26
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Windley MJ, Mann SA, Vandenberg JI, Hill AP. Temperature Effects on Kinetics of KV11.1 Drug Block Have Important Consequences for In Silico Proarrhythmic Risk Prediction. Mol Pharmacol 2016; 90:1-11. [PMID: 27190211 DOI: 10.1124/mol.115.103127] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 05/11/2016] [Indexed: 01/08/2023] Open
Abstract
Drug block of voltage-gated potassium channel subtype 11.1 human ether-a-go-go related gene (Kv11.1) (hERG) channels, encoded by the KCNH2 gene, is associated with reduced repolarization of the cardiac action potential and is the predominant cause of acquired long QT syndrome that can lead to fatal cardiac arrhythmias. Current safety guidelines require that potency of KV11.1 block is assessed in the preclinical phase of drug development. However, not all drugs that block KV11.1 are proarrhythmic, meaning that screening on the basis of equilibrium measures of block can result in high attrition of potentially low-risk drugs. The basis of the next generation of drug-screening approaches is set to be in silico risk prediction, informed by in vitro mechanistic descriptions of drug binding, including measures of the kinetics of block. A critical issue in this regard is characterizing the temperature dependence of drug binding. Specifically, it is important to address whether kinetics relevant to physiologic temperatures can be inferred or extrapolated from in vitro data gathered at room temperature in high-throughout systems. Here we present the first complete study of the temperature-dependent kinetics of block and unblock of a proarrhythmic drug, cisapride, to KV11.1. Our data highlight a complexity to binding that manifests at higher temperatures and can be explained by accumulation of an intermediate, non-blocking encounter-complex. These results suggest that for cisapride, physiologically relevant kinetic parameters cannot be simply extrapolated from those measured at lower temperatures; rather, data gathered at physiologic temperatures should be used to constrain in silico models that may be used for proarrhythmic risk prediction.
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Affiliation(s)
- Monique J Windley
- Computational Cardiology, Victor Chang Cardiac Research Institute, Darlinghurst, Australia (M.J.W., S.A.M., J.I.V., A.P.H.); and St. Vincent's Clinical School, University of New South Wales, Darlinghurst, Australia (S.A.M., J.I.V., A.P.H.)
| | - Stefan A Mann
- Computational Cardiology, Victor Chang Cardiac Research Institute, Darlinghurst, Australia (M.J.W., S.A.M., J.I.V., A.P.H.); and St. Vincent's Clinical School, University of New South Wales, Darlinghurst, Australia (S.A.M., J.I.V., A.P.H.)
| | - Jamie I Vandenberg
- Computational Cardiology, Victor Chang Cardiac Research Institute, Darlinghurst, Australia (M.J.W., S.A.M., J.I.V., A.P.H.); and St. Vincent's Clinical School, University of New South Wales, Darlinghurst, Australia (S.A.M., J.I.V., A.P.H.)
| | - Adam P Hill
- Computational Cardiology, Victor Chang Cardiac Research Institute, Darlinghurst, Australia (M.J.W., S.A.M., J.I.V., A.P.H.); and St. Vincent's Clinical School, University of New South Wales, Darlinghurst, Australia (S.A.M., J.I.V., A.P.H.)
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27
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Ganai SA. Strategy for enhancing the therapeutic efficacy of histone deacetylase inhibitor dacinostat: the novel paradigm to tackle monotonous cancer chemoresistance. Arch Pharm Res 2015:10.1007/s12272-015-0673-9. [PMID: 26481010 DOI: 10.1007/s12272-015-0673-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 10/13/2015] [Indexed: 01/01/2023]
Abstract
Histone deacetylases (HDACs) regulate gene expression by creating the closed state of chromatin via histone hypoacetylation. Histone acetylation deregulation caused by aberrant expression of classical HDACs leads to imprecise gene regulation culminating in various diseases including cancer. Histone deacetylase inhibitors (HDACi), the small-molecules modulating the biological function of HDACs have shown promising results in inducing cell cycle arrest, differentiation and apoptosis in tumour models. HDACi do not show desired cytotoxic effect when used in monotherapy due to triggering of various resistance mechanisms in cancer cells emphasizing the desperate need of novel strategies that can be used to overcome such challenges. The present article provides intricate details about the novel HDACi dacinostat (LAQ-824) against multiple myeloma and acute myeloid leukaemia. The distinct molecular mechanisms modulated by dacinostat in exerting cytotoxic effect against the defined malignancies have also been detailed. The article also explains the strategy that can be used to circumvent the conventional therapy resistant cases and for enhancing the therapeutic efficacy of dacinostat for effective anticancer therapy.
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Affiliation(s)
- Shabir Ahmad Ganai
- Plant Virology and Molecular Pathology Laboratory, Division of Plant Pathology, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shalimar, Srinagar, 190025, India.
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28
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Humphries ESA, Dart C. Neuronal and Cardiovascular Potassium Channels as Therapeutic Drug Targets: Promise and Pitfalls. JOURNAL OF BIOMOLECULAR SCREENING 2015; 20:1055-73. [PMID: 26303307 PMCID: PMC4576507 DOI: 10.1177/1087057115601677] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 07/26/2015] [Accepted: 07/28/2015] [Indexed: 12/21/2022]
Abstract
Potassium (K(+)) channels, with their diversity, often tissue-defined distribution, and critical role in controlling cellular excitability, have long held promise of being important drug targets for the treatment of dysrhythmias in the heart and abnormal neuronal activity within the brain. With the exception of drugs that target one particular class, ATP-sensitive K(+) (KATP) channels, very few selective K(+) channel activators or inhibitors are currently licensed for clinical use in cardiovascular and neurological disease. Here we review what a range of human genetic disorders have told us about the role of specific K(+) channel subunits, explore the potential of activators and inhibitors of specific channel populations as a therapeutic strategy, and discuss possible reasons for the difficulty in designing clinically relevant K(+) channel modulators.
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Affiliation(s)
| | - Caroline Dart
- Institute of Integrative Biology, University of Liverpool, UK
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29
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Büyükdeligöz M, Hocaoğlu N, Oransay K, Tunçok Y, Kalkan Ş. The Effects of the Adenosine Receptor Antagonists on the Reverse of Cardiovascular Toxic Effects Induced by Citalopram In-Vivo Rat Model of Poisoning. Balkan Med J 2015; 32:303-8. [PMID: 26185720 DOI: 10.5152/balkanmedj.2015.15932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 01/13/2015] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Citalopram is a selective serotonin reuptake inhibitor that requires routine cardiac monitoring to prevent a toxic dose. Prolongation of the QT interval has been observed in acute citalopram poisoning. Our previous experimental study showed that citalopram may be lead to QT prolongation by stimulating adenosine A1 receptors without affecting the release of adenosine. AIMS We examined the effects of adenosine receptor antagonists in reversing the cardiovascular toxic effects induced by citalopram in rats. STUDY DESIGN Animal experimentation. METHODS Rats were divided into three groups randomly (n=7 for each group). Sodium cromoglycate (20 mg/kg) was administered to all rats to inhibit adenosine A3 receptor mast cell activation. Citalopram toxicity was achieved by citalopram infusion (4 mg/kg/min) for 20 minutes. After citalopram infusion, in the control group (Group 1), rats were given an infusion of dextrose solution for 60 minutes. In treatment groups, the selective adenosine A1 antagonist DPCPX (Group 2, 8-cyclopentyl-1,3-dipropylxanthine, 20 μg/kg/min) or the selective A2a antagonist CSC (Group 3, 8-(3-chlorostyryl)caffeine, 24 μg/kg/min) was infused for 60 minutes. Mean arterial pressure (MAP), heart rate (HR), QRS duration and QT interval measurements were followed during the experiment period. Statistical analysis was performed by ANOVA followed by Tukey's multiple comparison tests. RESULTS Citalopram infusion reduced MAP and HR and prolonged the QT interval. It did not cause any significant difference in QRS duration in any group. When compared to the control group, DPCPX after citalopram infusion shortened the prolongation of the QT interval after 40, 50 and 60 minutes (p<0.01). DPCPX infusion shortened the prolongation of the QT interval at 60 minutes compared with the CSC group (p<0.05). CSC infusion shortened the prolongation of the QT at 60 minutes compared with the control group (p<0.05). CONCLUSION DPCPX improved QT interval prolongation in citalopram toxicity. The results of this study show that mechanism of cardiovascular toxicity induced by citalopram may be related adenosine A1 receptor stimulation. Adenosine A1 receptor antagonists may be used for the treatment of citalopram toxicity.
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Affiliation(s)
- Müjgan Büyükdeligöz
- Department of Medical Pharmacology, Dokuz Eylül University Faculty of Medicine, İzmir, Turkey
| | - Nil Hocaoğlu
- Department of Medical Pharmacology, Dokuz Eylül University Faculty of Medicine, İzmir, Turkey
| | - Kubilay Oransay
- Department of Medical Pharmacology, Dokuz Eylül University Faculty of Medicine, İzmir, Turkey
| | - Yeşim Tunçok
- Department of Medical Pharmacology, Dokuz Eylül University Faculty of Medicine, İzmir, Turkey
| | - Şule Kalkan
- Department of Medical Pharmacology, Dokuz Eylül University Faculty of Medicine, İzmir, Turkey
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30
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Perissinotti LL, Guo J, De Biase PM, Clancy CE, Duff HJ, Noskov SY. Kinetic model for NS1643 drug activation of WT and L529I variants of Kv11.1 (hERG1) potassium channel. Biophys J 2015; 108:1414-1424. [PMID: 25809254 PMCID: PMC4375712 DOI: 10.1016/j.bpj.2014.12.056] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 11/24/2014] [Accepted: 12/08/2014] [Indexed: 11/28/2022] Open
Abstract
Congenital and acquired (drug-induced) forms of the human long-QT syndrome are associated with alterations in Kv11.1 (hERG) channel-controlled repolarizing IKr currents of cardiac action potentials. A mandatory drug screen implemented by many countries led to a discovery of a large group of small molecules that can activate hERG currents and thus may act as potent antiarrhythmic agents. Despite significant progress in identification of channel activators, little is known about their mechanism of action. A combination of electrophysiological studies with molecular and kinetic modeling was used to examine the mechanism of a model activator (NS1643) action on the hERG channel and its L529I mutant. The L529I mutant has gating dynamics similar to that of wild-type while its response to application of NS1643 is markedly different. We propose a mechanism compatible with experiments in which the model activator binds to the closed (C3) and open states (O). We suggest that NS1643 is affecting early gating transitions, probably during movements of the voltage sensor that precede the opening of the activation gate.
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Affiliation(s)
- Laura L Perissinotti
- Centre for Molecular Modeling, Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, Canada
| | - Jiqing Guo
- Libin Cardiovascular Institute of Alberta, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Pablo M De Biase
- Centre for Molecular Modeling, Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, Canada
| | - Colleen E Clancy
- Department of Pharmacology, University of California at Davis, Davis, California.
| | - Henry J Duff
- Libin Cardiovascular Institute of Alberta, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
| | - Sergei Y Noskov
- Centre for Molecular Modeling, Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, Canada.
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31
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Molbaek K, Scharff-Poulsen P, Helix-Nielsen C, Klaerke DA, Pedersen PA. High yield purification of full-length functional hERG K+ channels produced in Saccharomyces cerevisiae. Microb Cell Fact 2015; 14:15. [PMID: 25656388 PMCID: PMC4341239 DOI: 10.1186/s12934-015-0193-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 12/11/2014] [Indexed: 11/23/2022] Open
Abstract
The hERG potassium channel is essential for repolarization of the cardiac action potential. Due to this vital function, absence of unintended and potentially life-threatening interactions with hERG is required for approval of new drugs. The structure of hERG is therefore one of the most sought-after. To provide purified hERG for structural studies and new hERG biomimetic platforms for detection of undesirable interactions, we have developed a hERG expression platform generating unprecedented amounts of purified and functional hERG channels. Full-length hERG, with or without a C-terminally fused green fluorescent protein (GFP) His 8-tag was produced from a codon-optimized hERG cDNA in Saccharomyces cerevisiae. Both constructs complemented the high potassium requirement of a knock-out Saccharomyces cerevisiae strain, indicating correct tetramer assembly in vivo. Functionality was further demonstrated by Astemizole binding to membrane embedded hERG-GFP-His 8 with a stoichiometry corresponding to tetramer assembly. The 156 kDa hERG-GFP protein accumulated to a membrane density of 1.6%. Fluorescence size exclusion chromatography of hERG-GFP-His 8 solubilized in Fos-Choline-12 supplemented with cholesteryl-hemisuccinate and Astemizole resulted in a monodisperse elution profile demonstrating a high quality of the hERG channels. hERG-GFP-His 8 purified by Ni-affinity chromatography maintained the ability to bind Astemizole with the correct stoichiometry indicating that the native, tetrameric structure was preserved. To our knowledge this is the first reported high-yield production and purification of full length, tetrameric and functional hERG. This significant breakthrough will be paramount in obtaining hERG crystal structures, and in establishment of new high-throughput hERG drug safety screening assays.
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Affiliation(s)
- Karen Molbaek
- Department of Veterinary and Clinical Animal Science, University of Copenhagen, Dyrlaegevej 100, Frederiksberg, DK-1870, Denmark.
| | - Peter Scharff-Poulsen
- Department of Biology, University of Copenhagen, Universitetsparken 13, Copenhagen OE, DK- 2100, Denmark.
| | - Claus Helix-Nielsen
- Department of Environmental Engineering, Technical University of Denmark, Miljoevej building 113, Kgs Lyngby, 24105, Denmark. .,Aquaporin A/S, Ole Maaloesvej 3, Copenhagen N, DK-2200, Denmark. .,Laboratory for Water Biophysics and Membrane Technology, University of Maribor, Smetanova ulica 17, Maribor, SL-2000, Slovenia.
| | - Dan A Klaerke
- Department of Veterinary and Clinical Animal Science, University of Copenhagen, Dyrlaegevej 100, Frederiksberg, DK-1870, Denmark.
| | - Per Amstrup Pedersen
- Department of Biology, University of Copenhagen, Universitetsparken 13, Copenhagen OE, DK- 2100, Denmark.
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Li P, Chen X, Zhang Q, Zheng Y, Jiang H, Yang H, Gao Z. The human ether-a-go-go-related gene activator NS1643 enhances epilepsy-associated KCNQ channels. J Pharmacol Exp Ther 2014; 351:596-604. [PMID: 25232191 DOI: 10.1124/jpet.114.217703] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Human ether-a-go-go-related gene (hERG) and KCNQ channels are two classes of voltage-gated potassium channels. Specific mutations have been identified that are causal for type II long QT (LQT2) syndrome, neonatal epilepsy, and benign familial neonatal convulsions. Increasing evidence from clinical studies suggests that LQT2 and epilepsy coexist in some patients. Therefore, an integral approach to investigating and treating the two diseases is likely more effective. In the current study, we found that NS1643 [1,3-bis-(2-hydroxy-5-trifluoromethyl-phenyl)-urea], a previously reported hERG activator, is also an activator of KCNQ channels. It potentiates the neuronal KCNQ2, KCNQ4, and KCNQ2/Q3 channels, but not the cardiac KCNQ1. The effects of NS1643 on the KCNQ2 channel include left shifting of voltage for reaching 50% of the maximum conductance and slowing of deactivation. Analysis of the dose-response curve of NS1643 revealed an EC50 value of 2.44 ± 0.25 μM. A hydrophobic phenylalanine (F137) located at the middle region of the voltage-sensing domain was identified as critical for NS1643 activity on KCNQ2. When testing NS1643 effects in rescuing LQT2 hERG mutants and the KCNQ2 BFNC mutants, we found it is particularly efficacious in some cases. Considering the substantial relationship between LQT2 and epilepsy, these findings reveal that NS1643 is a useful compound to elucidate the causal connection of LQT2 and epilepsy. More generally, this may provide a strategy in the development of therapeutics for LQT2 and epilepsy.
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Affiliation(s)
- Ping Li
- CAS Key Laboratory of Receptor Research (P.L., X.C., Y.Z., Z.G.), and State Key Laboratory of Drug Research (Q.Z., H.J., H.Y.), Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xueqin Chen
- CAS Key Laboratory of Receptor Research (P.L., X.C., Y.Z., Z.G.), and State Key Laboratory of Drug Research (Q.Z., H.J., H.Y.), Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Qiansen Zhang
- CAS Key Laboratory of Receptor Research (P.L., X.C., Y.Z., Z.G.), and State Key Laboratory of Drug Research (Q.Z., H.J., H.Y.), Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yueming Zheng
- CAS Key Laboratory of Receptor Research (P.L., X.C., Y.Z., Z.G.), and State Key Laboratory of Drug Research (Q.Z., H.J., H.Y.), Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Hualiang Jiang
- CAS Key Laboratory of Receptor Research (P.L., X.C., Y.Z., Z.G.), and State Key Laboratory of Drug Research (Q.Z., H.J., H.Y.), Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Huaiyu Yang
- CAS Key Laboratory of Receptor Research (P.L., X.C., Y.Z., Z.G.), and State Key Laboratory of Drug Research (Q.Z., H.J., H.Y.), Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Zhaobing Gao
- CAS Key Laboratory of Receptor Research (P.L., X.C., Y.Z., Z.G.), and State Key Laboratory of Drug Research (Q.Z., H.J., H.Y.), Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
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Nachimuthu S, Assar MD, Schussler JM. Drug-induced QT interval prolongation: mechanisms and clinical management. Ther Adv Drug Saf 2014; 3:241-53. [PMID: 25083239 DOI: 10.1177/2042098612454283] [Citation(s) in RCA: 188] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The prolonged QT interval is both widely seen and associated with the potentially deadly rhythm, Torsades de Pointes (TdP). While it can occur spontaneously in the congenital form, there is a wide array of drugs that have been implicated in the prolongation of the QT interval. Some of these drugs have either been restricted or withdrawn from the market due to the increased incidence of fatal polymorphic ventricular tachycardia. The list of drugs that cause QT prolongation continues to grow, and an updated list of specific drugs that prolong the QT interval can be found at www.qtdrugs.org. This review focuses on the mechanism of drug-induced QT prolongation, risk factors for TdP, culprit drugs, prevention and monitoring of prolonged drug-induced QT prolongation and treatment strategies.
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Affiliation(s)
- Senthil Nachimuthu
- Baylor University Medical Center, Jack and Jane Hamilton, Heart and Vascular Hospital Dallas, TX, USA
| | - Manish D Assar
- Baylor University Medical Center, Jack and Jane Hamilton, Heart and Vascular Hospital Dallas, TX, USA
| | - Jeffrey M Schussler
- Baylor University Medical Center, Jack and Jane Hamilton, Heart and Vascular Hospital, 621 North Hall Street, Suite 500, Dallas, TX 75226, USA
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HAN SHENGNA, YANG SONGHUA, ZHANG YU, SUN XIAOYAN, DUAN YANYAN, HU XIANGJIE, FAN TIANLI, HUANG CHENZHENG, YANG GE, ZHANG ZHAO, ZHANG LIRONG. Identification and functional characterization of the human ether-a-go-go-related gene Q738X mutant associated with hereditary long QT syndrome type 2. Int J Mol Med 2014; 34:810-5. [DOI: 10.3892/ijmm.2014.1827] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 06/23/2014] [Indexed: 11/06/2022] Open
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Ranjan AP, Mukerjee A, Helson L, Vishwanatha JK. Mitigating prolonged QT interval in cancer nanodrug development for accelerated clinical translation. J Nanobiotechnology 2013; 11:40. [PMID: 24330336 PMCID: PMC3878673 DOI: 10.1186/1477-3155-11-40] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 12/11/2013] [Indexed: 11/19/2022] Open
Abstract
Background Cardiac toxicity is the foremost reason for drug discontinuation from development to clinical evaluation and post market surveillance [Fung 35:293-317, 2001; Piccini 158:317-326 2009]. The Food and Drug Administration (FDA) has rejected many potential pharmaceutical agents due to QT prolongation effects. Since drug development and FDA approval takes an enormous amount of time, money and effort with high failure rates, there is an increased focus on rescuing drugs that cause QT prolongation. If these otherwise safe and potent drugs were formulated in a unique way so as to mitigate the QT prolongation associated with them, these potent drugs may get FDA approval for clinical use. Rescuing these compounds not only benefit the patients who need them but also require much less time and money thus leading to faster clinical translation. In this study, we chose curcumin as our drug of choice since it has been shown to posses anti-tumor properties against various cancers with limited toxicity. The major limitations with this pharmacologically active drug are (a) its ability to prolong QT by inhibiting the hERG channel and (b) its low bioavailability. In our previous studies, we found that lipids have protective actions against hERG channel inhibition and therefore QT prolongation. Results Results of the manual patch clamp assay of HEK 293 cells clearly illustrated that our hybrid nanocurcumin formulation prevented the curcumin induced inhibition of hERG K+ channel at concentrations higher than the therapeutic concentrations of curcumin. Comparing the percent inhibition, the hybrid nanocurcumin limited inhibition to 24.8% at a high curcumin equivalent concentration of 18 μM. Liposomal curcumin could only decrease this inhibition upto 30% only at lower curcumin concentration of 6 μM but not at 18 μM concentration. Conclusions Here we show a curcumin encapsulated lipopolymeric hybrid nanoparticle formulation which could protect against QT prolongation and also render increased bioavailability and stability thereby overcoming the limitations associated with curcumin.
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Affiliation(s)
| | | | | | - Jamboor K Vishwanatha
- Department of Molecular Biology & Immunology and Institute for Cancer Research, Graduate School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA.
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Indexing molecules for their hERG liability. Eur J Med Chem 2013; 65:304-14. [DOI: 10.1016/j.ejmech.2013.04.059] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 04/25/2013] [Accepted: 04/27/2013] [Indexed: 12/15/2022]
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Structure of the C-terminal region of an ERG channel and functional implications. Proc Natl Acad Sci U S A 2013; 110:11648-53. [PMID: 23801759 DOI: 10.1073/pnas.1306887110] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The human ether-à-go-go-related gene (hERG) encodes a K(+) channel crucial for repolarization of the cardiac action potential. EAG-related gene (ERG) channels contain a C-terminal cyclic nucleotide-binding homology domain coupled to the pore of the channel by a C-linker. Here, we report the structure of the C-linker/cyclic nucleotide-binding homology domain of a mosquito ERG channel at 2.5-Å resolution. The structure reveals that the region expected to form the cyclic nucleotide-binding pocket is negatively charged and is occupied by a short β-strand, referred to as the intrinsic ligand, explaining the lack of direct regulation of ERG channels by cyclic nucleotides. In hERG channels, the intrinsic ligand harbors hereditary mutations associated with long-QT syndrome (LQTS), a potentially lethal cardiac arrhythmia. Mutations in the intrinsic ligand affected hERG channel gating and LQTS mutations abolished hERG currents and altered trafficking of hERG channels, which explains the LQT phenotype. The structure also reveals a dramatically different conformation of the C-linker compared with the structures of the related ether-à-go-go-like K(+) and hyperpolarization-activated cyclic nucleotide-modulated channels, suggesting that the C-linker region may be highly dynamic in the KCNH, hyperpolarization-activated cyclic nucleotide-modulated, and cyclic nucleotide-gated channels.
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Identification and characterization of a novel genetic mutation with prolonged QT syndrome in an unexplained postoperative death. Int J Legal Med 2013; 128:105-15. [DOI: 10.1007/s00414-013-0853-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 03/19/2013] [Indexed: 10/27/2022]
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The promiscuous binding of pharmaceutical drugs and their transporter-mediated uptake into cells: what we (need to) know and how we can do so. Drug Discov Today 2012. [PMID: 23207804 DOI: 10.1016/j.drudis.2012.11.008] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A recent paper in this journal sought to counter evidence for the role of transport proteins in effecting drug uptake into cells, and questions that transporters can recognize drug molecules in addition to their endogenous substrates. However, there is abundant evidence that both drugs and proteins are highly promiscuous. Most proteins bind to many drugs and most drugs bind to multiple proteins (on average more than six), including transporters (mutations in these can determine resistance); most drugs are known to recognise at least one transporter. In this response, we alert readers to the relevant evidence that exists or is required. This needs to be acquired in cells that contain the relevant proteins, and we highlight an experimental system for simultaneous genome-wide assessment of carrier-mediated uptake in a eukaryotic cell (yeast).
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Campbell K, Calvo CJ, Mironov S, Herron T, Berenfeld O, Jalife J. Spatial gradients in action potential duration created by regional magnetofection of hERG are a substrate for wavebreak and turbulent propagation in cardiomyocyte monolayers. J Physiol 2012; 590:6363-79. [PMID: 23090949 DOI: 10.1113/jphysiol.2012.238758] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Spatial dispersion of action potential duration (APD) is a substrate for the maintenance of cardiac fibrillation, but the mechanisms are poorly understood. We investigated the role played by spatial APD dispersion in fibrillatory dynamics. We used an in vitro model in which spatial gradients in the expression of ether-à-go-go-related (hERG) protein, and thus rapid delayed rectifying K(+) current (I(Kr)) density, served to generate APD dispersion, high-frequency rotor formation, wavebreak and fibrillatory conduction. A unique adenovirus-mediated magnetofection technique generated well-controlled gradients in hERG and green fluorescent protein (GFP) expression in neonatal rat ventricular myocyte monolayers. Computer simulations using a realistic neonatal rat ventricular myocyte monolayer model provided crucial insight into the underlying mechanisms. Regional hERG overexpression shortened APD and increased rotor incidence in the hERG overexpressing region. An APD profile at 75 percent repolarization with a 16.6 ± 0.72 ms gradient followed the spatial profile of hERG-GFP expression; conduction velocity was not altered. Rotors in the infected region whose maximal dominant frequency was 12.9 Hz resulted in wavebreak at the interface (border zone) between infected and non-infected regions; dominant frequency distribution was uniform when the maximal dominant frequency was <12.9 Hz or the rotors resided in the uninfected region. Regularity at the border zone was lowest when rotors resided in the infected region. In simulations, a fivefold regional increase in I(Kr) abbreviated the APD and hyperpolarized the resting potential. However, the steep APD gradient at the border zone proved to be the primary mechanism of wavebreak and fibrillatory conduction. This study provides insight at the molecular level into the mechanisms by which spatial APD dispersion contributes to wavebreak, rotor stabilization and fibrillatory conduction.
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Affiliation(s)
- Katherine Campbell
- Center for Arrhythmia Research, Department of InternalMedicine, University of Michigan, Ann Arbor, MI 48108, USA
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Liu Q, Mao X, Zeng F, Jin S, Yang X. Effect of daurisoline on HERG channel electrophysiological function and protein expression. JOURNAL OF NATURAL PRODUCTS 2012; 75:1539-1545. [PMID: 22974355 DOI: 10.1021/np300232b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Daurisoline (1) is a bis-benzylisoquinoline alkaloid isolated from the rhizomes of Menispermum dauricum. The antiarrhythmic effect of 1 has been demonstrated in different experimental animals. In previous studies, daurisoline (1) prolonged action potential duration (APD) in a normal use-dependent manner. However, the electrophysiological mechanisms for 1-induced prolongation of APD have not been documented. In the present study, the direct effect of 1 was investigated on the hERG current and the expression of mRNA and protein in human embryonic kidney 293 (HEK293) cells stably expressing the hERG channel. It was shown that 1 inhibits hERG current in a concentration- and voltage-dependent manner. In the presence of 10 μM 1, steady-state inactivation of V(1/2) was shifted negatively by 15.9 mV, and 1 accelerated the onset of inactivation. Blockade of hERG channels was dependent on channel opening. The expression and function of hERG were unchanged by 1 at 1 and 10 μM, while hERG expression and the hERG current were decreased significantly by 1 at 30 μM. These results indicate that 1, at concentrations below 30 μM, exerts a blocking effect on hERG, but does not affect the expression and function of the hERG channel. This may explain the relatively lower risk of long QT syndrome after long-term usage.
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Affiliation(s)
- Qiangni Liu
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology , The Key Laboratory of Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Wuhan, Hubei, 430030, People's Republic of China
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Blunck R, Batulan Z. Mechanism of electromechanical coupling in voltage-gated potassium channels. Front Pharmacol 2012; 3:166. [PMID: 22988442 PMCID: PMC3439648 DOI: 10.3389/fphar.2012.00166] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 08/24/2012] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated ion channels play a central role in the generation of action potentials in the nervous system. They are selective for one type of ion - sodium, calcium, or potassium. Voltage-gated ion channels are composed of a central pore that allows ions to pass through the membrane and four peripheral voltage sensing domains that respond to changes in the membrane potential. Upon depolarization, voltage sensors in voltage-gated potassium channels (Kv) undergo conformational changes driven by positive charges in the S4 segment and aided by pairwise electrostatic interactions with the surrounding voltage sensor. Structure-function relations of Kv channels have been investigated in detail, and the resulting models on the movement of the voltage sensors now converge to a consensus; the S4 segment undergoes a combined movement of rotation, tilt, and vertical displacement in order to bring 3-4e(+) each through the electric field focused in this region. Nevertheless, the mechanism by which the voltage sensor movement leads to pore opening, the electromechanical coupling, is still not fully understood. Thus, recently, electromechanical coupling in different Kv channels has been investigated with a multitude of techniques including electrophysiology, 3D crystal structures, fluorescence spectroscopy, and molecular dynamics simulations. Evidently, the S4-S5 linker, the covalent link between the voltage sensor and pore, plays a crucial role. The linker transfers the energy from the voltage sensor movement to the pore domain via an interaction with the S6 C-termini, which are pulled open during gating. In addition, other contact regions have been proposed. This review aims to provide (i) an in-depth comparison of the molecular mechanisms of electromechanical coupling in different Kv channels; (ii) insight as to how the voltage sensor and pore domain influence one another; and (iii) theoretical predictions on the movement of the cytosolic face of the Kv channels during gating.
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Affiliation(s)
- Rikard Blunck
- Groupe d’étude des protéines membranairesMontreal, QC, Canada
- Department of Physiology, Université de MontréalMontreal, QC, Canada
- Department of Physics, Université de MontréalMontreal, QC, Canada
| | - Zarah Batulan
- Groupe d’étude des protéines membranairesMontreal, QC, Canada
- Department of Physiology, Université de MontréalMontreal, QC, Canada
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Tan PS, Perry MD, Ng CA, Vandenberg JI, Hill AP. Voltage-sensing domain mode shift is coupled to the activation gate by the N-terminal tail of hERG channels. ACTA ACUST UNITED AC 2012; 140:293-306. [PMID: 22891279 PMCID: PMC3434099 DOI: 10.1085/jgp.201110761] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Human ether-a-go-go–related gene (hERG) potassium channels exhibit unique gating kinetics characterized by unusually slow activation and deactivation. The N terminus of the channel, which contains an amphipathic helix and an unstructured tail, has been shown to be involved in regulation of this slow deactivation. However, the mechanism of how this occurs and the connection between voltage-sensing domain (VSD) return and closing of the gate are unclear. To examine this relationship, we have used voltage-clamp fluorometry to simultaneously measure VSD motion and gate closure in N-terminally truncated constructs. We report that mode shifting of the hERG VSD results in a corresponding shift in the voltage-dependent equilibrium of channel closing and that at negative potentials, coupling of the mode-shifted VSD to the gate defines the rate of channel closure. Deletion of the first 25 aa from the N terminus of hERG does not alter mode shifting of the VSD but uncouples the shift from closure of the cytoplasmic gate. Based on these observations, we propose the N-terminal tail as an adaptor that couples voltage sensor return to gate closure to define slow deactivation gating in hERG channels. Furthermore, because the mode shift occurs on a time scale relevant to the cardiac action potential, we suggest a physiological role for this phenomenon in maximizing current flow through hERG channels during repolarization.
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Affiliation(s)
- Peter S Tan
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
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Targeted cancer therapy: giving histone deacetylase inhibitors all they need to succeed. Future Med Chem 2012; 4:505-24. [PMID: 22416777 DOI: 10.4155/fmc.12.3] [Citation(s) in RCA: 296] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Histone deacetylase inhibitors (HDACis) have now emerged as a powerful new class of small-molecule therapeutics acting through the regulation of the acetylation states of histone proteins (a form of epigenetic modulation) and other non-histone protein targets. Over 490 clinical trials have been initiated in the last 10 years, culminating in the approval of two structurally distinct HDACis - SAHA (vorinostat, Zolinza™) and FK228 (romidepsin, Istodax™). However, the current HDACis have serious limitations, including ineffectively low concentrations in solid tumors and cardiac toxicity, which is hindering their progress in the clinic. Herein, we review the primary paradigms being pursued to overcome these hindrances, including HDAC isoform selectivity, localized administration, and targeting cap groups to achieve selective tissue and cell type distribution.
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Kinoshita K, Yamaguchi Y, Nishide K, Kimoto K, Nonobe Y, Fujita A, Asano K, Tabata T, Mori H, Inoue H, Hata Y, Fukurotani K, Nishida N. A novel missense mutation causing a G487R substitution in the S2-S3 loop of human ether-à-go-go-related gene channel. J Cardiovasc Electrophysiol 2012; 23:1246-53. [PMID: 22764740 DOI: 10.1111/j.1540-8167.2012.02383.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Mutations of human ether-à-go-go-related gene (hERG), which encodes a cardiac K(+) channel responsible for the acceleration of the repolarizing phase of an action potential and the prevention of premature action potential regeneration, often cause severe arrhythmic disorders. We found a novel missense mutation of hERG that results in a G487R substitution in the S2-S3 loop of the channel subunit [hERG(G487R)] from a family and determined whether this mutant gene could induce an abnormality in channel function. METHODS AND RESULTS We made whole-cell voltage-clamp recordings from HEK-293T cells transfected with wild-type hERG [hERG(WT)], hERG(G487R), or both. We measured hERG channel-mediated current as the "tail" of a depolarization-elicited current. The current density of the tail current and its voltage- and time-dependences were not different among all the cell groups. The time-courses of deactivation, inactivation, and recovery from inactivation and their voltage-dependences were not different among all the cell groups. Furthermore, we performed immunocytochemical analysis using an anti-hERG subunit antibody. The ratio of the immunoreactivity of the plasma membrane to that of the cytoplasm was not different between cells transfected with hERG(WT), hERG(G487R), or both. CONCLUSION hERG(G487R) can produce functional channels with normal gating kinetics and cell-surface expression efficiency with or without the aid of hERG(WT). Therefore, neither the heterozygous nor homozygous inheritance of hERG(G487R) is thought to cause severe cardiac disorders. hERG(G487R) would be a candidate for a rare variant or polymorphism of hERG with an amino acid substitution in the unusual region of the channel subunit.
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Affiliation(s)
- Koshi Kinoshita
- Department of Legal Medicine Second, Graduate School of Medical and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
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Jonsson MKB, van der Heyden MAG, van Veen TAB. Deciphering hERG channels: molecular basis of the rapid component of the delayed rectifier potassium current. J Mol Cell Cardiol 2012; 53:369-74. [PMID: 22742967 DOI: 10.1016/j.yjmcc.2012.06.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Revised: 06/07/2012] [Accepted: 06/19/2012] [Indexed: 12/23/2022]
Abstract
The rapid component of the delayed rectifier potassium current (I(Kr)), encoded by the ether-a-go-go-related gene (ERG1, officially denominated as KCNH2), is a major contributor to repolarization in the mammalian heart. Acute (e.g. drug-induced) and chronic (e.g. inherited genetic disorder) disruptions of this current can lead to prolongation of the action potential and potentiate occurrence of lethal arrhythmias. Many cardiac and non-cardiac drugs show high affinity for the I(Kr) channel and it is therefore extensively studied during safety pharmacology. The unique biophysical and pharmacological properties of the I(Kr) channel are largely recapitulated by expressing the human variant (hERG1a) in overexpressing systems. hERG1a channels are tetramers consisting of four 1159 amino acid long proteins and have electrophysiological properties similar, but not identical, to native I(Kr). In the search for an explanation to the discrepancies between I(Kr) and hERG1a channels, two alternative hERG1 proteins have been found. Alternative transcription of hERG1 leads to a protein with a 56 amino acid shorter N-terminus, known as hERG1b. hERG1b can form channels alone or coassemble with hERG1a. Alternative splicing leads to an alternate C-terminus and a protein known as hERGuso. hERGuso and hERG1b regulate hERG1a channel trafficking, functional expression and channel kinetics. Expression of hERGuso leads to a reduced number of channels at the plasma membrane and thereby reduces current density. On the contrary, co-assembly with hERG1b alters channel kinetics resulting in more available channels and a larger current. These findings have implication for understanding mechanisms of disease, acute and chronic drug effects, and potential gender differences.
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Affiliation(s)
- Malin K B Jonsson
- Department of Medical Physiology, Division Heart and Lungs, University Medical Center Utrecht, Utrecht, The Netherlands.
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Peterson LB, Eskew JD, Vielhauer GA, Blagg BSJ. The hERG channel is dependent upon the Hsp90α isoform for maturation and trafficking. Mol Pharm 2012; 9:1841-6. [PMID: 22554505 DOI: 10.1021/mp300138n] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Heat shock protein 90 (Hsp90) has emerged as a promising therapeutic target for the treatment of cancer. Several Hsp90 inhibitors have entered clinical trials. However, some toxicological detriments have arisen, such as cardiotoxicity resulting from hERG inhibition following the administration of Hsp90 inhibitors. We sought to investigate this toxicity as hERG has been previously reported as a client protein that depends upon Hsp90 for its maturation and functional trafficking. In this study we show that hERG depends upon a single Hsp90 isoform. hERG preferentially co-immunoprecipitated with Hsp90α, and genetic knockdown of Hsp90α, but not Hsp90β, resulted in a trafficking-defective hERG channel. This study demonstrates the importance of delineating the isoform dependence of Hsp90 client proteins and provides rationale for the design of isoform-selective Hsp90 inhibitors that avoid detrimental effects.
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Affiliation(s)
- Laura B Peterson
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
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Ng CA, Torres AM, Pagès G, Kuchel PW, Vandenberg JI. Insights into hERG K+ channel structure and function from NMR studies. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 42:71-9. [DOI: 10.1007/s00249-012-0808-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 03/07/2012] [Accepted: 03/13/2012] [Indexed: 01/09/2023]
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Guo J, Zhang X, Hu Z, Zhuang Z, Zhu Z, Chen Z, Chen W, Zhao Z, Zhang C, Zhang Z. A422T mutation in HERG potassium channel retained in ER is rescurable by pharmacologic or molecular chaperones. Biochem Biophys Res Commun 2012; 422:305-10. [PMID: 22580281 DOI: 10.1016/j.bbrc.2012.04.153] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 04/27/2012] [Indexed: 10/28/2022]
Abstract
In the present study, we characterized biologic and electrophysiologic consequences of A422T mutation in HERG K(+) channel and the role of pharmacologic or molecular chaperons by employing a heterogeneous expression system in HEK 293 cells. It was found that A422T mutation led to a marked decrease in whole-cell recording currents, and that a complexly glycosylated form protein band at 155 kDa was missing by Western blotting analysis compared to wild type (WT). And the mutant protein was mainly located in the cytoplasm as illustrated in immunocytochemical assay, indicating that the mutation underwent a trafficking defect. In addition, A422T mutation exerted remarkable dominant-negative suppression on WT, resulting in the alteration in the kinetic processes. Strikingly, trafficking-deficient A422T mutation was partially rescued by incubating the cells at a lower temperature, administration of pharmacologic chaperon, E4031 or overexpression of a chaperon molecule, Hsp90, but not Hsp70. In conclusion, missense A422T mutation in HERG K(+) channel results in its trafficking defect, which is rescurable by pharmacologic or molecular chaperones.
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Affiliation(s)
- Jia Guo
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing 210046, China
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Möller C. Keeping the rhythm: hERG and beyond in cardiovascular safety pharmacology. Expert Rev Clin Pharmacol 2012; 3:321-9. [PMID: 22111613 DOI: 10.1586/ecp.10.24] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Following its involvement in life-threatening cardiac arrhythmias, the catchword 'hERG' has become infamous in the drug discovery community. The blockade of the ion channel coded by the human ether-á-go-go-related gene (hERG) has been correlated to a prolongation of the QT interval in the ECG, which again is correlated to a potential risk of a life-threatening polymorphic ventricular tachycardia - torsades de pointes (TdP). Therefore, in vitro investigations for blockade of this ion channel have become a standard, starting early in most drug discovery projects and often accompanying the whole project; at some stage, scientists in many medicinal chemistry programs have to deal with hERG channel liabilities. Data for the compound effects on hERG channel activity are generally part of the safety pharmacology risk assessment in regulatory submissions and, at this stage, are ideally conducted in compliance with good laboratory practice. With the withdrawal of clobutinol from the market, owing to its perceived risk of introducing TdP, the importance of the hERG channel has very recently been reconfirmed. Despite being of such importance for drug discovery, the relevance and impact of hERG data are sometimes misinterpreted, as there are drugs that block the hERG-coded ion channel but do not cause TdP, and drugs that cause TdP but do not block the hERG channel. This review aims to provide an overview of TdP, including the cardiac action potential and the ion channels involved in it, as well as on the relevance and interpretation of in vitro hERG channel data and their impact for drug discovery projects. Finally, novel cardiac safety test systems beyond in vitro hERG channel screening are discussed.
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Affiliation(s)
- Clemens Möller
- Evotec AG, Discovery Alliances, Schnackenburgallee 114, Hamburg, Germany.
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