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Kashiwa A, Itoh H, Makiyama T, Wada Y, Ozawa J, Kato K, Fukuyama M, Nakajima T, Ohno S, Horie M. Clinical characterization of type 1 long QT syndrome caused by C-terminus Kv7.1 variants. Heart Rhythm 2024; 21:1113-1120. [PMID: 38367891 DOI: 10.1016/j.hrthm.2024.02.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 01/27/2024] [Accepted: 02/07/2024] [Indexed: 02/19/2024]
Abstract
BACKGROUND Variants in the KCNQ1 gene, encoding the α-subunit of the slow component of delayed rectifier K+ channel Kv7.1, cause long QT syndrome (LQTS) type 1. The location of variants may be one of the factors in determining prognosis. However, detailed genotype-phenotype relationships associated with C-terminus variants remain unelucidated. OBJECTIVE We investigated the clinical characteristics and variant-specific arrhythmic risks in patients with LQTS carrying Kv7.1 C-terminus variants. METHODS The study comprises 202 consecutive patients with LQTS (98 probands and 104 family members) who carry a rare heterozygous variant in the Kv7.1 C-terminus. Their clinical characteristics and arrhythmic events were investigated. RESULTS We identified 36 unique C-terminus variants (25 missense and 11 non-missense). The p.R366W variant was identified in 8 families, and p.T587M was identified in 21 families in large numbers from northwestern Japan. As for the location of the variant, we found that the variants in highly conserved regions and nonhelical domains were associated with longer QTc intervals compared with the variants in other regions. Both p.R366W and p.T587M variants are located in the highly conserved and functionally pivotal regions close to helices A and D, which are associated with calmodulin binding and channel assembly (tetramerization), respectively. The probands carrying p.T587M and p.R366W variants had worse arrhythmia outcomes compared with those with other C-terminus variants. The haplotype analysis of p.T587M families was suggestive of a founder effect. CONCLUSION The arrhythmic risk of C-terminus variants in Kv7.1 in LQTS is not homogeneous, and locations of variants can be a determining factor for prognosis.
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Affiliation(s)
- Asami Kashiwa
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan; Department of Cardiology, Niigata City General Hospital, Niigata, Japan.
| | - Hideki Itoh
- Division of Patient Safety, Hiroshima University Hospital, Minami-ku, Hiroshima, Japan
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yuko Wada
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Junichi Ozawa
- Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Koichi Kato
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Megumi Fukuyama
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Tadashi Nakajima
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Seiko Ohno
- Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Minoru Horie
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
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2
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Wada Y, Wang L, Hall LD, Yang T, Short LL, Solus JF, Glazer AM, Roden DM. The electrophysiologic effects of KCNQ1 extend beyond expression of IKs: evidence from genetic and pharmacologic block. Cardiovasc Res 2024; 120:735-744. [PMID: 38442735 PMCID: PMC11135641 DOI: 10.1093/cvr/cvae042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 01/22/2024] [Accepted: 02/01/2024] [Indexed: 03/07/2024] Open
Abstract
AIMS While variants in KCNQ1 are the commonest cause of the congenital long QT syndrome, we and others find only a small IKs in cardiomyocytes from human-induced pluripotent stem cells (iPSC-CMs) or human ventricular myocytes. METHODS AND RESULTS We studied population control iPSC-CMs and iPSC-CMs from a patient with Jervell and Lange-Nielsen (JLN) syndrome due to compound heterozygous loss-of-function (LOF) KCNQ1 variants. We compared the effects of pharmacologic IKs block to those of genetic KCNQ1 ablation, using JLN cells, cells homozygous for the KCNQ1 LOF allele G643S, or siRNAs reducing KCNQ1 expression. We also studied the effects of two blockers of IKr, the other major cardiac repolarizing current, in the setting of pharmacologic or genetic ablation of KCNQ1: moxifloxacin, associated with a very low risk of drug-induced long QT, and dofetilide, a high-risk drug. In control cells, a small IKs was readily recorded but the pharmacologic IKs block produced no change in action potential duration at 90% repolarization (APD90). In contrast, in cells with genetic ablation of KCNQ1 (JLN), baseline APD90 was markedly prolonged compared with control cells (469 ± 20 vs. 310 ± 16 ms). JLN cells displayed increased sensitivity to acute IKr block: the concentration (μM) of moxifloxacin required to prolong APD90 100 msec was 237.4 [median, interquartile range (IQR) 100.6-391.6, n = 7] in population cells vs. 23.7 (17.3-28.7, n = 11) in JLN cells. In control cells, chronic moxifloxacin exposure (300 μM) mildly prolonged APD90 (10%) and increased IKs, while chronic exposure to dofetilide (5 nM) produced greater prolongation (67%) and no increase in IKs. However, in the siRNA-treated cells, moxifloxacin did not increase IKs and markedly prolonged APD90. CONCLUSION Our data strongly suggest that KCNQ1 expression modulates baseline cardiac repolarization, and the response to IKr block, through mechanisms beyond simply generating IKs.
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Affiliation(s)
- Yuko Wada
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Lili Wang
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Lynn D Hall
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Tao Yang
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Laura L Short
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Joseph F Solus
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Andrew M Glazer
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
| | - Dan M Roden
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
- Departments of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt University Medical Center, 2215B Garland Ave, 1285 MRBIV, Nashville, TN 37232, USA
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3
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Reisqs JB, Qu YS, Boutjdir M. Ion channel trafficking implications in heart failure. Front Cardiovasc Med 2024; 11:1351496. [PMID: 38420267 PMCID: PMC10899472 DOI: 10.3389/fcvm.2024.1351496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/25/2024] [Indexed: 03/02/2024] Open
Abstract
Heart failure (HF) is recognized as an epidemic in the contemporary world, impacting around 1%-2% of the adult population and affecting around 6 million Americans. HF remains a major cause of mortality, morbidity, and poor quality of life. Several therapies are used to treat HF and improve the survival of patients; however, despite these substantial improvements in treating HF, the incidence of HF is increasing rapidly, posing a significant burden to human health. The total cost of care for HF is USD 69.8 billion in 2023, warranting a better understanding of the mechanisms involved in HF. Among the most serious manifestations associated with HF is arrhythmia due to the electrophysiological changes within the cardiomyocyte. Among these electrophysiological changes, disruptions in sodium and potassium currents' function and trafficking, as well as calcium handling, all of which impact arrhythmia in HF. The mechanisms responsible for the trafficking, anchoring, organization, and recycling of ion channels at the plasma membrane seem to be significant contributors to ion channels dysfunction in HF. Variants, microtubule alterations, or disturbances of anchoring proteins lead to ion channel trafficking defects and the alteration of the cardiomyocyte's electrophysiology. Understanding the mechanisms of ion channels trafficking could provide new therapeutic approaches for the treatment of HF. This review provides an overview of the recent advances in ion channel trafficking in HF.
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Affiliation(s)
- Jean-Baptiste Reisqs
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY, United States
| | - Yongxia Sarah Qu
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY, United States
- Department of Cardiology, New York Presbyterian Brooklyn Methodist Hospital, New York, NY, United States
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY, United States
- Department of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Health Sciences University, New York, NY, United States
- Department of Medicine, New York University Grossman School of Medicine, New York, NY, United States
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4
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Stevens TL, Coles S, Sturm AC, Hoover CA, Borzok MA, Mohler PJ, El Refaey M. Molecular Pathways and Animal Models of Arrhythmias. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1441:1057-1090. [PMID: 38884769 DOI: 10.1007/978-3-031-44087-8_67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Arrhythmias account for over 300,000 annual deaths in the United States, and approximately half of all deaths are associated with heart disease. Mechanisms underlying arrhythmia risk are complex; however, work in humans and animal models over the past 25 years has identified a host of molecular pathways linked with both arrhythmia substrates and triggers. This chapter will focus on select arrhythmia pathways solved by linking human clinical and genetic data with animal models.
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Affiliation(s)
- Tyler L Stevens
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Sara Coles
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Amy C Sturm
- Genomic Medicine Institute, 23andMe, Sunnyvale, CA, USA
| | - Catherine A Hoover
- Department of Biochemistry, Chemistry, Engineering and Physics, Commonwealth University of Pennsylvania, Mansfield, PA, USA
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Maegen A Borzok
- Department of Biochemistry, Chemistry, Engineering and Physics, Commonwealth University of Pennsylvania, Mansfield, PA, USA
| | - Peter J Mohler
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Mona El Refaey
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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5
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Cócera-Ortega L, Wilders R, Kamps SC, Fabrizi B, Huber I, van der Made I, van den Bout A, de Vries DK, Gepstein L, Verkerk AO, Pinto YM, Tijsen AJ. shRNAs Targeting a Common KCNQ1 Variant Could Alleviate Long-QT1 Disease Severity by Inhibiting a Mutant Allele. Int J Mol Sci 2022; 23:ijms23074053. [PMID: 35409410 PMCID: PMC9000197 DOI: 10.3390/ijms23074053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/31/2022] [Accepted: 04/04/2022] [Indexed: 12/02/2022] Open
Abstract
Long-QT syndrome type 1 (LQT1) is caused by mutations in KCNQ1. Patients heterozygous for such a mutation co-assemble both mutant and wild-type KCNQ1-encoded subunits into tetrameric Kv7.1 potassium channels. Here, we investigated whether allele-specific inhibition of mutant KCNQ1 by targeting a common variant can shift the balance towards increased incorporation of the wild-type allele to alleviate the disease in human-induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs). We identified the single nucleotide polymorphisms (SNP) rs1057128 (G/A) in KCNQ1, with a heterozygosity of 27% in the European population. Next, we determined allele-specificity of short-hairpin RNAs (shRNAs) targeting either allele of this SNP in hiPSC-CMs that carry an LQT1 mutation. Our shRNAs downregulated 60% of the A allele and 40% of the G allele without affecting the non-targeted allele. Suppression of the mutant KCNQ1 allele by 60% decreased the occurrence of arrhythmic events in hiPSC-CMs measured by a voltage-sensitive reporter, while suppression of the wild-type allele increased the occurrence of arrhythmic events. Furthermore, computer simulations based on another LQT1 mutation revealed that 60% suppression of the mutant KCNQ1 allele shortens the prolonged action potential in an adult cardiomyocyte model. We conclude that allele-specific inhibition of a mutant KCNQ1 allele by targeting a common variant may alleviate the disease. This novel approach avoids the need to design shRNAs to target every single mutation and opens up the exciting possibility of treating multiple LQT1-causing mutations with only two shRNAs.
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Affiliation(s)
- Lucía Cócera-Ortega
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (L.C.-O.); (S.C.K.); (B.F.); (I.v.d.M.); (A.v.d.B.); (D.K.d.V.); (A.O.V.); (Y.M.P.)
| | - Ronald Wilders
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands;
| | - Selina C. Kamps
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (L.C.-O.); (S.C.K.); (B.F.); (I.v.d.M.); (A.v.d.B.); (D.K.d.V.); (A.O.V.); (Y.M.P.)
| | - Benedetta Fabrizi
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (L.C.-O.); (S.C.K.); (B.F.); (I.v.d.M.); (A.v.d.B.); (D.K.d.V.); (A.O.V.); (Y.M.P.)
| | - Irit Huber
- The Sohnis Family Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion—Israel Institute of Technology, Haifa 3109601, Israel; (I.H.); (L.G.)
| | - Ingeborg van der Made
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (L.C.-O.); (S.C.K.); (B.F.); (I.v.d.M.); (A.v.d.B.); (D.K.d.V.); (A.O.V.); (Y.M.P.)
| | - Anouk van den Bout
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (L.C.-O.); (S.C.K.); (B.F.); (I.v.d.M.); (A.v.d.B.); (D.K.d.V.); (A.O.V.); (Y.M.P.)
| | - Dylan K. de Vries
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (L.C.-O.); (S.C.K.); (B.F.); (I.v.d.M.); (A.v.d.B.); (D.K.d.V.); (A.O.V.); (Y.M.P.)
| | - Lior Gepstein
- The Sohnis Family Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion—Israel Institute of Technology, Haifa 3109601, Israel; (I.H.); (L.G.)
| | - Arie O. Verkerk
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (L.C.-O.); (S.C.K.); (B.F.); (I.v.d.M.); (A.v.d.B.); (D.K.d.V.); (A.O.V.); (Y.M.P.)
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands;
| | - Yigal M. Pinto
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (L.C.-O.); (S.C.K.); (B.F.); (I.v.d.M.); (A.v.d.B.); (D.K.d.V.); (A.O.V.); (Y.M.P.)
| | - Anke J. Tijsen
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (L.C.-O.); (S.C.K.); (B.F.); (I.v.d.M.); (A.v.d.B.); (D.K.d.V.); (A.O.V.); (Y.M.P.)
- Correspondence: ; Tel.: +31-205668544
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6
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Tada H, Fujino N, Hayashi K, Kawashiri MA, Takamura M. Human genetics and its impact on cardiovascular disease. J Cardiol 2022; 79:233-239. [PMID: 34551866 DOI: 10.1016/j.jjcc.2021.09.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 08/24/2021] [Indexed: 12/15/2022]
Abstract
Cardiovascular disease (CVD) is a major cause of death worldwide. Given that CVD is a highly heritable trait, researchers have attempted to fully understand the genetic basis of CVD for a long time. The human genome comprises 3,100 Mbp per haploid genome and 6,200 Mbp in total (diploid genome). However, there is a tendency for rare genetic variations to exhibit a large effect size, whereas common genetic variations have a small effect on diseases, because of natural selection. In this sense, dividing genetic variations into two groups based on allele frequency (and effect sizes on diseases) is a good idea. We know there are several important genes (especially lipid-related genes) in which rare genetic variations are apparently associated with CVD risk, while a polygenic risk score comprising common genetic variations appears to work quite well among general populations. That information can be used not only for risk stratification but also for discoveries for novel pharmacologic targets. In this review article, we provide the important and simple idea that human genetics is important for CVD because it is a highly heritable trait, and we believe that it will lead to precision medicine in this field.
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Affiliation(s)
- Hayato Tada
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan.
| | - Noboru Fujino
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Kenshi Hayashi
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Masa-Aki Kawashiri
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Masayuki Takamura
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
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7
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Kashiwa A, Hosaka Y, Takahashi K, Ohno S, Wada Y, Makiyama T, Oda H, Horie M. Pueraria mirifica, an estrogenic tropical herb, unveiled the severity of Type 1 LQTS caused by KCNQ1-T587M. J Arrhythm 2021; 37:1114-1116. [PMID: 34386142 PMCID: PMC8339079 DOI: 10.1002/joa3.12576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 05/07/2021] [Accepted: 05/22/2021] [Indexed: 11/09/2022] Open
Abstract
After taking an estrogen-containing supplement derived from a tropical plant Pueraria mirifica, a 24-year-old woman presented marked QT prolongation and repetitive torsade de pointes. The patient was found to carry a heterozygous KCNQ1-T587M mutation. This is the first report on Pueraria mirifica-related acquired long QT syndrome.
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Affiliation(s)
- Asami Kashiwa
- Department of Cardiovascular MedicineKyoto University Graduate School of MedicineKyotoJapan
- Department of Cardiovascular MedicineNiigata City General HospitalNiigataJapan
| | - Yukio Hosaka
- Department of Cardiovascular MedicineNiigata City General HospitalNiigataJapan
| | - Kazuyoshi Takahashi
- Department of Cardiovascular MedicineNiigata City General HospitalNiigataJapan
| | - Seiko Ohno
- Department of Bioscience and GeneticsNational Cerebral and Cardiovascular CenterOsakaJapan
| | - Yuko Wada
- Vanderbilt Center for Arrhythmia Research and TherapeuticsDivision of Clinical PharmacologyDepartment of MedicineVanderbilt University Medical CenterNashvilleTNUSA
- Department of Cardiovascular MedicineShiga University of Medical ScienceShigaJapan
| | - Takeru Makiyama
- Department of Cardiovascular MedicineKyoto University Graduate School of MedicineKyotoJapan
| | - Hirotaka Oda
- Department of Cardiovascular MedicineNiigata City General HospitalNiigataJapan
| | - Minoru Horie
- Department of Cardiovascular MedicineShiga University of Medical ScienceShigaJapan
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8
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Chakrabarty S, Govindaraj P, Sankaran BP, Nagappa M, Kabekkodu SP, Jayaram P, Mallya S, Deepha S, Ponmalar JNJ, Arivinda HR, Meena AK, Jha RK, Sinha S, Gayathri N, Taly AB, Thangaraj K, Satyamoorthy K. Contribution of nuclear and mitochondrial gene mutations in mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. J Neurol 2021; 268:2192-2207. [PMID: 33484326 PMCID: PMC8179915 DOI: 10.1007/s00415-020-10390-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 12/27/2020] [Accepted: 12/28/2020] [Indexed: 11/30/2022]
Abstract
Background Mitochondrial disorders are clinically complex and have highly variable phenotypes among all inherited disorders. Mutations in mitochon
drial DNA (mtDNA) and nuclear genome or both have been reported in mitochondrial diseases suggesting common pathophysiological pathways. Considering the clinical heterogeneity of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) phenotype including focal neurological deficits, it is important to look beyond mitochondrial gene mutation. Methods The clinical, histopathological, biochemical analysis for OXPHOS enzyme activity, and electron microscopic, and neuroimaging analysis was performed to diagnose 11 patients with MELAS syndrome with a multisystem presentation. In addition, whole exome sequencing (WES) and whole mitochondrial genome sequencing were performed to identify nuclear and mitochondrial mutations. Results Analysis of whole mtDNA sequence identified classical pathogenic mutation m.3243A > G in seven out of 11 patients. Exome sequencing identified pathogenic mutation in several nuclear genes associated with mitochondrial encephalopathy, sensorineural hearing loss, diabetes, epilepsy, seizure and cardiomyopathy (POLG, DGUOK, SUCLG2, TRNT1, LOXHD1, KCNQ1, KCNQ2, NEUROD1, MYH7) that may contribute to classical mitochondrial disease phenotype alone or in combination with m.3243A > G mutation. Conclusion Individuals with MELAS exhibit clinical phenotypes with varying degree of severity affecting multiple systems including auditory, visual, cardiovascular, endocrine, and nervous system. This is the first report to show that nuclear genetic factors influence the clinical outcomes/manifestations of MELAS subjects alone or in combination with m.3243A > G mutation. Electronic supplementary material The online version of this article (10.1007/s00415-020-10390-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sanjiban Chakrabarty
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, India
| | - Periyasamy Govindaraj
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.,Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.,Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.,Institute of Bioinformatics, International Tech Park, Bangalore, India.,Manipal Academy of Higher Education, Manipal, India
| | - Bindu Parayil Sankaran
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.,Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.,Genetic Metabolic Disorders Service, Children's Hospital At Westmead, Sydney, NSW, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Madhu Nagappa
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.,Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Shama Prasada Kabekkodu
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, India
| | - Pradyumna Jayaram
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, India
| | - Sandeep Mallya
- Department of Bioinformatics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, India
| | - Sekar Deepha
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.,Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - J N Jessiena Ponmalar
- Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Hanumanthapura R Arivinda
- Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | | | - Rajan Kumar Jha
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Sanjib Sinha
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Narayanappa Gayathri
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.,Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Arun B Taly
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.,Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Kumarasamy Thangaraj
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| | - Kapaettu Satyamoorthy
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, India.
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Popescu MC, Lee YJ, Kim SS, Wade HM, Papakyrikos AM, Darling LEO. The phosphorylation state of both hERG and KvLQT1 mediates protein-protein interactions between these complementary cardiac potassium channel alpha subunits. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183556. [PMID: 33444623 DOI: 10.1016/j.bbamem.2021.183556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 12/22/2020] [Accepted: 01/04/2021] [Indexed: 11/16/2022]
Abstract
KvLQT1 and hERG are the α-subunits of the voltage-gated K+ channels which carry the cardiac repolarizing currents IKs and IKr, respectively. These currents function in vivo with some redundancy to maintain appropriate action potential durations (APDs) in cardiomyocytes. As such, protein-protein interactions between hERG and KvLQT1 may be important in normal cardiac electrophysiology, as well as in arrhythmia and sudden cardiac death. Previous phenomenological observations of functional, mutual downregulation between these complementary repolarizing currents in transgenic rabbit models and human cell culture motivate our investigations into protein-protein interactions between hERG and KvLQT1. Previous data suggest that a dynamic, physical interaction between hERG and KvLQT1 modulates the respective currents. However, the mechanism by which hERG-KvLQT1 interactions are regulated is still poorly understood. Phosphorylation is proposed to play a role since modifying the phosphorylation state of each protein has been shown to alter channel kinetics, and both hERG and KvLQT1 are targets of the Ser/Thr protein kinase PKA, activated by elevated intracellular cAMP. In this work, quantitative apFRET analyses of phosphonull and phosphomimetic hERG and KvLQT1 mutants indicate that unphosphorylated hERG does not interact with KvLQT1, suggesting that hERG phosphorylation is important for wild-type proteins to interact. For proteins already potentially interacting, phosphorylation of KvLQT1 appears to be the driving factor abrogating hERG-KvLQT1 interaction. This work increases our knowledge about hERG-KvLQT1 interactions, which may contribute to the efforts to elucidate mechanisms that underlie many types of arrhythmias, and also further characterizes novel protein-protein interactions between two distinct potassium channel families.
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Affiliation(s)
- Medeea C Popescu
- Department of Biological Sciences and Biochemistry Program, Wellesley College, 106 Central St., Wellesley, MA 02481, United States of America
| | - Yeon J Lee
- Department of Biological Sciences and Biochemistry Program, Wellesley College, 106 Central St., Wellesley, MA 02481, United States of America
| | - Stephanie S Kim
- Department of Biological Sciences and Biochemistry Program, Wellesley College, 106 Central St., Wellesley, MA 02481, United States of America
| | - Heidi M Wade
- Department of Biological Sciences and Biochemistry Program, Wellesley College, 106 Central St., Wellesley, MA 02481, United States of America
| | - Amanda M Papakyrikos
- Department of Biological Sciences and Biochemistry Program, Wellesley College, 106 Central St., Wellesley, MA 02481, United States of America
| | - Louise E O Darling
- Department of Biological Sciences and Biochemistry Program, Wellesley College, 106 Central St., Wellesley, MA 02481, United States of America.
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Wu X, Larsson HP. Insights into Cardiac IKs (KCNQ1/KCNE1) Channels Regulation. Int J Mol Sci 2020; 21:ijms21249440. [PMID: 33322401 PMCID: PMC7763278 DOI: 10.3390/ijms21249440] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/05/2020] [Accepted: 12/09/2020] [Indexed: 12/19/2022] Open
Abstract
The delayed rectifier potassium IKs channel is an important regulator of the duration of the ventricular action potential. Hundreds of mutations in the genes (KCNQ1 and KCNE1) encoding the IKs channel cause long QT syndrome (LQTS). LQTS is a heart disorder that can lead to severe cardiac arrhythmias and sudden cardiac death. A better understanding of the IKs channel (here called the KCNQ1/KCNE1 channel) properties and activities is of great importance to find the causes of LQTS and thus potentially treat LQTS. The KCNQ1/KCNE1 channel belongs to the superfamily of voltage-gated potassium channels. The KCNQ1/KCNE1 channel consists of both the pore-forming subunit KCNQ1 and the modulatory subunit KCNE1. KCNE1 regulates the function of the KCNQ1 channel in several ways. This review aims to describe the current structural and functional knowledge about the cardiac KCNQ1/KCNE1 channel. In addition, we focus on the modulation of the KCNQ1/KCNE1 channel and its potential as a target therapeutic of LQTS.
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Abstract
This review is focusing on the understanding of various factors and components governing and controlling the occurrence of ventricular arrhythmias including (i) the role of various ion channel-related changes in the action potential (AP), (ii) electrocardiograms (ECGs), (iii) some important arrhythmogenic mediators of reperfusion, and pharmacological approaches to their attenuation. The transmembrane potential in myocardial cells is depending on the cellular concentrations of several ions including sodium, calcium, and potassium on both sides of the cell membrane and active or inactive stages of ion channels. The movements of Na+, K+, and Ca2+ via cell membranes produce various currents that provoke AP, determining the cardiac cycle and heart function. A specific channel has its own type of gate, and it is opening and closing under specific transmembrane voltage, ionic, or metabolic conditions. APs of sinoatrial (SA) node, atrioventricular (AV) node, and Purkinje cells determine the pacemaker activity (depolarization phase 4) of the heart, leading to the surface manifestation, registration, and evaluation of ECG waves in both animal models and humans. AP and ECG changes are key factors in arrhythmogenesis, and the analysis of these changes serve for the clarification of the mechanisms of antiarrhythmic drugs. The classification of antiarrhythmic drugs may be based on their electrophysiological properties emphasizing the connection between basic electrophysiological activities and antiarrhythmic properties. The review also summarizes some important mechanisms of ventricular arrhythmias in the ischemic/reperfused myocardium and permits an assessment of antiarrhythmic potential of drugs used for pharmacotherapy under experimental and clinical conditions.
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Affiliation(s)
- Arpad Tosaki
- Department of Pharmacology, School of Pharmacy, University of Debrecen, Debrecen, Hungary
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