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Follmer ML, Isner T, Ozekin YH, Levitt C, Bates EA. Depolarization induces calcium-dependent BMP4 release from mouse embryonic palate mesenchyme. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.11.598333. [PMID: 38915514 PMCID: PMC11195066 DOI: 10.1101/2024.06.11.598333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Ion channels are essential for proper morphogenesis of the craniofacial skeleton. However, the molecular mechanisms underlying this phenomenon are unknown. Loss of the Kcnj2 potassium channel disrupts Bone Morphogenetic Protein (BMP) signaling within the developing palate. BMP signaling is essential for the correct development of several skeletal structures, including the palate, though little is known about the mechanisms that govern BMP secretion. We introduce a tool to image the release of bone morphogenetic protein 4 (BMP4) from mammalian cells. Using this tool, we show that depolarization induces BMP4 release from mouse embryonic palate mesenchyme cells in a calcium-dependent manner. We show native transient changes in intracellular calcium occur in cranial neural crest cells, the cells from which embryonic palate mesenchyme derives. Waves of transient changes in intracellular calcium suggest that these cells are electrically coupled and may temporally coordinate BMP release. These transient changes in intracellular calcium persist in palate mesenchyme cells from embryonic day (E) 9.5 to 13.5 mice. Disruption of Kcnj2 significantly decreases the amplitude of calcium transients and the ability of cells to secrete BMP. Together, these data suggest that temporal control of developmental cues is regulated by ion channels, depolarization, and changes in intracellular calcium for mammalian craniofacial morphogenesis. SUMMARY We show that embryonic palate mesenchyme cells undergo transient changes in intracellular calcium. Depolarization of these cells induces BMP4 release suggesting that ion channels are a node in BMP4 signaling.
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Harraz OF, Delpire E. Recent insights into channelopathies. Physiol Rev 2024; 104:23-31. [PMID: 37561136 DOI: 10.1152/physrev.00022.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/12/2023] [Accepted: 08/05/2023] [Indexed: 08/11/2023] Open
Affiliation(s)
- Osama F Harraz
- Department of Pharmacology, Larner College of Medicine, Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, Vermont, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical School, Nashville, Tennessee, United States
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee, United States
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3
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George LF, Follmer ML, Fontenoy E, Moran HR, Brown JR, Ozekin YH, Bates EA. Endoplasmic Reticulum Calcium Mediates Drosophila Wing Development. Bioelectricity 2023; 5:290-306. [PMID: 38143873 PMCID: PMC10733776 DOI: 10.1089/bioe.2022.0036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2023] Open
Abstract
Background The temporal dynamics of morphogen presentation impacts transcriptional responses and tissue patterning. However, the mechanisms controlling morphogen release are far from clear. We found that inwardly rectifying potassium (Irk) channels regulate endogenous transient increases in intracellular calcium and bone morphogenetic protein (BMP/Dpp) release for Drosophila wing development. Inhibition of Irk channels reduces BMP/Dpp signaling, and ultimately disrupts wing morphology. Ion channels impact development of several tissues and organisms in which BMP signaling is essential. In neurons and pancreatic beta cells, Irk channels modulate membrane potential to affect intracellular Ca++ to control secretion of neurotransmitters and insulin. Based on Irk activity in neurons, we hypothesized that electrical activity controls endoplasmic reticulum (ER) Ca++ release into the cytoplasm to regulate the release of BMP. Materials and Methods To test this hypothesis, we reduced expression of four proteins that control ER calcium, Stromal interaction molecule 1 (Stim), Calcium release-activated calcium channel protein 1 (Orai), SarcoEndoplasmic Reticulum Calcium ATPase (SERCA), small conductance calcium-activated potassium channel (SK), and Bestrophin 2 (Best2) using RNAi and documented wing phenotypes. We use live imaging to study calcium and Dpp release within pupal wings and larval wing discs. Additionally, we employed immunohistochemistry to characterize Small Mothers Against Decapentaplegic (SMAD) phosphorylation downstream of the BMP/Dpp pathway following RNAi knockdown. Results We found that reduced Stim and SERCA function decreases amplitude and frequency of endogenous calcium transients in the wing disc and reduced BMP/Dpp release. Conclusion Our results suggest control of ER calcium homeostasis is required for BMP/Dpp release, and Drosophila wing development.
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Affiliation(s)
- Laura Faith George
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Mikaela Lynn Follmer
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Emily Fontenoy
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Hannah Rose Moran
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Jeremy Ryan Brown
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Yunus H. Ozekin
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Emily Anne Bates
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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4
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Manuel AIM, Gutiérrez LK, Pedrosa MLV, Uréndez FMC, Jiménez FJB, Carrascoso IM, Pérez PS, Macías Á, Jalife J. Molecular stratification of arrhythmogenic mechanisms in the Andersen Tawil Syndrome. Cardiovasc Res 2022; 119:919-932. [PMID: 35892314 PMCID: PMC10153646 DOI: 10.1093/cvr/cvac118] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 06/20/2022] [Accepted: 07/01/2022] [Indexed: 11/12/2022] Open
Abstract
Andersen Tawil Syndrome (ATS) is a rare inheritable disease associated with loss-of-function mutations in KCNJ2, the gene coding the strong inward rectifier potassium channel Kir2.1, which forms an essential membrane protein controlling cardiac excitability. ATS is usually marked by a triad of periodic paralysis, life-threatening cardiac arrhythmias and dysmorphic features, but its expression is variable and not all patients with a phenotype linked to ATS have a known genetic alteration. The mechanisms underlying this arrhythmogenic syndrome are poorly understood. Knowing such mechanisms would be essential to distinguish ATS from other channelopathies with overlapping phenotypes and to develop individualized therapies. For example, the recently suggested role of Kir2.1 as a countercurrent to sarcoplasmic calcium reuptake might explain the arrhythmogenic mechanisms of ATS and its overlap with catecholaminergic polymorphic ventricular tachycardia (CPVT). Here we summarize current knowledge on the mechanisms of arrhythmias leading to sudden cardiac death in ATS. We first provide an overview of the syndrome and its pathophysiology, from the patient´s bedside to the protein, and discuss the role of essential regulators and interactors that could play a role in cases of ATS. The review highlights novel ideas related to some post-translational channel interactions with partner proteins that might help define the molecular bases of the arrhythmia phenotype. We then propose a new all-embracing classification of the currently known ATS loss-of-function mutations according to their position in the Kir2.1 channel structure and their functional implications. We also discuss specific ATS pathogenic variants, their clinical manifestations and treatment stratification. The goal is to provide a deeper mechanistic understanding of the syndrome toward the development of novel targets and personalized treatment strategies.
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Affiliation(s)
| | - Lilian K Gutiérrez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain
| | | | | | - Francisco José Bermúdez Jiménez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain.,Departamento de Cardiología, Hospital Virgen de las Nieves, GranadaSpain
| | | | - Patricia Sánchez Pérez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain
| | - Álvaro Macías
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain
| | - José Jalife
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) Carlos III, 28029 Madrid, Spain.,CIBER de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain.,Departments of Medicine and Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
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5
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Villar-Quiles RN, Sternberg D, Tredez G, Beatriz Romero N, Evangelista T, Lafôret P, Cintas P, Sole G, Sacconi S, Bendahhou S, Franques J, Cances C, Noury JB, Delmont E, Blondy P, Perrin L, Hezode M, Fournier E, Fontaine B, Stojkovic T, Vicart S. Phenotypical variability and atypical presentations in a French cohort of Andersen-Tawil syndrome. Eur J Neurol 2022; 29:2398-2411. [PMID: 35460302 DOI: 10.1111/ene.15369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/31/2022] [Accepted: 04/18/2022] [Indexed: 11/03/2022]
Abstract
BACKGROUND AND PURPOSE Andersen-Tawil syndrome (ATS) is a skeletal muscle channelopathy caused by KCNJ2 mutations, characterized by a clinical triad of periodic paralysis, cardiac arrhythmias and dysmorphism. The muscle phenotype, particularly the atypical forms with prominent permanent weakness or predominantly painful symptoms, remains incompletely characterized. METHODS A retrospective clinical, histological, electroneuromyography (ENMG) and genetic analysis of molecularly confirmed ATS patients, diagnosed and followed up at neuromuscular reference centers in France, was conducted. RESULTS Thirty-five patients from 27 unrelated families carrying 17 different missense KCNJ2 mutations (four novel mutations) and a heterozygous KCNJ2 duplication are reported. The typical triad was observed in 42.9% of patients. Cardiac abnormalities were observed in 65.7%: 56.5% asymptomatic and 39.1% requiring antiarrhythmic drugs. 71.4% of patients exhibited dysmorphic features. Muscle symptoms were reported in 85.7%, amongst whom 13.3% had no cardiopathy and 33.3% no dysmorphic features. Periodic paralysis was present in 80% and was significantly more frequent in men. Common triggers were exercise, immobility and carbohydrate-rich diet. Ictal serum potassium concentrations were low in 53.6%. Of the 35 patients, 45.7% had permanent weakness affecting proximal muscles, which was mild and stable or slowly progressive over several decades. Four patients presented with exercise-induced pain and myalgia attacks. Diagnostic delay was 14.4 ± 9.5 years. ENMG long-exercise test performed in 25 patients (71.4%) showed in all a decremental response up to 40%. Muscle biopsy performed in 12 patients revealed tubular aggregates in six patients (associated in two of them with vacuolar lesions), dystrophic features in one patient and non-specific myopathic features in one patient; it was normal in four patients. DISCUSSION Recognition of atypical features (exercise-induced pain or myalgia and permanent weakness) along with any of the elements of the triad should arouse suspicion. The ENMG long-exercise test has a high diagnostic yield and should be performed. Early diagnosis is of utmost importance to improve disease prognosis.
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Affiliation(s)
- Rocio Nur Villar-Quiles
- Reference Center for Neuromuscular Disorders, APHP, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France.,Institute of Myology, Centre de Recherche en Myologie, UMRS974, Sorbonne Université - INSERM, Paris, France
| | - Damien Sternberg
- Reference Center for Muscle Channelopathies, Service de Biochimie et Centre de Génétique, APHP, Pitié-Salpêtrière Hospital, Paris, France
| | - Grégoire Tredez
- Reference Center for Neuromuscular Disorders, APHP, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France
| | - Norma Beatriz Romero
- Institute of Myology, Centre de Recherche en Myologie, UMRS974, Sorbonne Université - INSERM, Paris, France.,Neuromuscular Morphology Unit, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France
| | - Teresinha Evangelista
- Reference Center for Neuromuscular Disorders, APHP, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France.,Institute of Myology, Centre de Recherche en Myologie, UMRS974, Sorbonne Université - INSERM, Paris, France.,Neuromuscular Morphology Unit, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France
| | - Pascal Lafôret
- Reference Center for Neuromuscular Disorders, APHP, Raymond-Poincaré Hospital, Paris, France
| | - Pascal Cintas
- Neurology Department, Pierre-Paul Riquet Hospital, CHU Toulouse, Toulouse, France
| | - Guilhem Sole
- Reference Centre for Neuromuscular Disorders, Pellegrin Hospital CHU Bordeaux, Bordeaux, France
| | - Sabrina Sacconi
- Neuromuscular Diseases and ALS Specialized Center, University of Nice-Sophia Antipolis, Nice, France
| | - Said Bendahhou
- UMR7370 CNRS, LP2M, Labex ICST, Faculty of Medicine, University of Nice-Sophia Antipolis, Nice, France
| | - Jérôme Franques
- Assistance Publique-Hôpitaux de Marseille, Department of Neurology and Neuromuscular Diseases, La Timone Hospital, Marseille, France
| | - Claude Cances
- AOC (Atlantique-Occitanie-Caraïbe) Reference Centre for Neuromuscular Disorders, Neuropediatric Department, Toulouse University Hospital, Toulouse, France
| | - J B Noury
- Neurology Department, Neuromuscular Center, CHRU Cavale Blanche, Brest, France
| | - Emilien Delmont
- Department of Neurology, University Hospital Timone, Marseille, France
| | - Patricia Blondy
- Reference Center for Muscle Channelopathies, Service de Biochimie et Centre de Génétique, APHP, Pitié-Salpêtrière Hospital, Paris, France
| | - Laurence Perrin
- Pediatrics Department, APHP, Robert-Débré Hospital, Paris, France
| | - Marianne Hezode
- Reference Center for Neuromuscular Disorders, APHP, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France
| | - Emmanuel Fournier
- Reference Center for Neuromuscular Disorders, APHP, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France
| | - Bertrand Fontaine
- Reference Center for Neuromuscular Disorders, APHP, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France.,Institute of Myology, Centre de Recherche en Myologie, UMRS974, Sorbonne Université - INSERM, Paris, France.,Reference Center for Muscle Channelopathies, APHP, Institut de Myologie, Pitié-Salpêtrière Hospital, Paris, France
| | - Tanya Stojkovic
- Reference Center for Neuromuscular Disorders, APHP, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France.,Institute of Myology, Centre de Recherche en Myologie, UMRS974, Sorbonne Université - INSERM, Paris, France
| | - Savine Vicart
- Reference Center for Neuromuscular Disorders, APHP, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France.,Reference Center for Muscle Channelopathies, APHP, Institut de Myologie, Pitié-Salpêtrière Hospital, Paris, France
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Qiao P, Schrecke S, Lyu J, Zhu Y, Zhang T, Benavides A, Laganowsky A. Insight into the Phospholipid-Binding Preferences of Kir3.4. Biochemistry 2021; 60:3813-3821. [PMID: 34846128 DOI: 10.1021/acs.biochem.1c00615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The G-protein-gated inwardly rectifying potassium channel 4 (Kir3.4) subunit forms functional tetramers. Previous studies have established that phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is required for Kir3.4 function. However, the binding preferences of Kir3.4 for the headgroup and acyl chains of phosphorylated phosphatidylinositides (PIPs) and other lipids are not well understood. Here, the interactions between full-length, human Kir3.4 and lipids are characterized using native mass spectrometry (MS) in conjunction with a soluble fluorescent lipid-binding assay. Kir3.4 displays binding preferences for PIPs, and, in some cases, the degree of binding is influenced by the type of acyl chains. The interactions between Kir3.4 and PIPs are weaker in comparison to full-length, human Kir3.2. The binding of PI(4,5)P2 modified with a fluorophore to Kir3.2 can be enhanced by other lipids, such as phosphatidylcholine. Introduction of S143T, a mutation that enhances Kir3.4 activity, results in an overall reduction in the channel binding PIPs. In contrast, the D223N mutant of Kir3.4 that mimics the sodium-bound state exhibited stronger binding for PI(4,5)P2, particularly for those with 18:0-20:4 acyl chains. Taken together, these results provide additional insight into the interaction between Kir3.4 and lipids that are important for channel function.
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Affiliation(s)
- Pei Qiao
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, United States
| | - Samantha Schrecke
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Jixing Lyu
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Yun Zhu
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Tianqi Zhang
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Amanda Benavides
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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7
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Kir Channel Molecular Physiology, Pharmacology, and Therapeutic Implications. Handb Exp Pharmacol 2021; 267:277-356. [PMID: 34345939 DOI: 10.1007/164_2021_501] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For the past two decades several scholarly reviews have appeared on the inwardly rectifying potassium (Kir) channels. We would like to highlight two efforts in particular, which have provided comprehensive reviews of the literature up to 2010 (Hibino et al., Physiol Rev 90(1):291-366, 2010; Stanfield et al., Rev Physiol Biochem Pharmacol 145:47-179, 2002). In the past decade, great insights into the 3-D atomic resolution structures of Kir channels have begun to provide the molecular basis for their functional properties. More recently, computational studies are beginning to close the time domain gap between in silico dynamic and patch-clamp functional studies. The pharmacology of these channels has also been expanding and the dynamic structural studies provide hope that we are heading toward successful structure-based drug design for this family of K+ channels. In the present review we focus on placing the physiology and pharmacology of this K+ channel family in the context of atomic resolution structures and in providing a glimpse of the promising future of therapeutic opportunities.
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Abstract
The physiological heart function is controlled by a well-orchestrated interplay of different ion channels conducting Na+, Ca2+ and K+. Cardiac K+ channels are key players of cardiac repolarization counteracting depolarizating Na+ and Ca2+ currents. In contrast to Na+ and Ca2+, K+ is conducted by many different channels that differ in activation/deactivation kinetics as well as in their contribution to different phases of the action potential. Together with modulatory subunits these K+ channel α-subunits provide a wide range of repolarizing currents with specific characteristics. Moreover, due to expression differences, K+ channels strongly influence the time course of the action potentials in different heart regions. On the other hand, the variety of different K+ channels increase the number of possible disease-causing mutations. Up to now, a plethora of gain- as well as loss-of-function mutations in K+ channel forming or modulating proteins are known that cause severe congenital cardiac diseases like the long-QT-syndrome, the short-QT-syndrome, the Brugada syndrome and/or different types of atrial tachyarrhythmias. In this chapter we provide a comprehensive overview of different K+ channels in cardiac physiology and pathophysiology.
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Park JW, Kim KA, Park JY. Effect of Memantine on QT/QTc Interval in a Healthy Korean Population. Clin Pharmacol Drug Dev 2021; 10:1209-1215. [PMID: 33761171 DOI: 10.1002/cpdd.931] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 02/08/2021] [Indexed: 12/25/2022]
Abstract
Studies on the effects of memantine on QT prolongation have yielded conflicting results. For a long time, memantine was reported to be a safe drug without QT prolongation; however, several case studies have reported memantine-induced QT prolongation in Alzheimer's patients. This study evaluated the relationship between memantine blood levels, and QT interval changes. Over a 2-week period, we orally administered 20 mg of memantine daily to achieve a steady state in 57 healthy Korean subjects. We measured and analyzed the QT interval and blood memantine concentrations simultaneously before and after treatment, as well as 2 weeks after the last dosing. Correlation analysis was done between blood memantine level and QT interval. No serious adverse events occurred during the study period. Repeated dosing of memantine did not show clinically significant QT interval changes after treatment. Regression analysis was performed based on the results; there was no statistical association between memantine blood level and QT prolongation. In conclusion, the results of the present study demonstrated no clinically significant changes in the QT interval with therapeutic blood levels of memantine.
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Affiliation(s)
- Jin-Woo Park
- Department of Clinical Pharmacology and Toxicology, Anam Hospital, Korea University College of Medicine, Seoul, Korea
| | - Kyoung-Ah Kim
- Department of Clinical Pharmacology and Toxicology, Anam Hospital, Korea University College of Medicine, Seoul, Korea
| | - Ji-Young Park
- Department of Clinical Pharmacology and Toxicology, Anam Hospital, Korea University College of Medicine, Seoul, Korea
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Neurological Disorders and Risk of Arrhythmia. Int J Mol Sci 2020; 22:ijms22010188. [PMID: 33375447 PMCID: PMC7795827 DOI: 10.3390/ijms22010188] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/19/2020] [Accepted: 12/24/2020] [Indexed: 01/08/2023] Open
Abstract
Neurological disorders including depression, anxiety, post-traumatic stress disorder (PTSD), schizophrenia, autism and epilepsy are associated with an increased incidence of cardiovascular disorders and susceptibility to heart failure. The underlying molecular mechanisms that link neurological disorders and adverse cardiac function are poorly understood. Further, a lack of progress is likely due to a paucity of studies that investigate the relationship between neurological disorders and cardiac electrical activity in health and disease. Therefore, there is an important need to understand the spatiotemporal behavior of neurocardiac mechanisms. This can be advanced through the identification and validation of neurological and cardiac signaling pathways that may be adversely regulated. In this review we highlight how dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system (ANS) activity and inflammation, predispose to psychiatric disorders and cardiac dysfunction. Moreover, antipsychotic and antidepressant medications increase the risk for adverse cardiac events, mostly through the block of the human ether-a-go-go-related gene (hERG), which plays a critical role in cardiac repolarization. Therefore, understanding how neurological disorders lead to adverse cardiac ion channel remodeling is likely to have significant implications for the development of effective therapeutic interventions and helps improve the rational development of targeted therapeutics with significant clinical implications.
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Abstract
Andersen-Tawil syndrome (ATS) is a very rare orphan genetic multisystem channelopathy without structural heart disease (with rare exceptions). ATS type 1 is inherited in an autosomal dominant fashion and is caused by mutations in the KCNJ2 gene, which encodes the α subunit of the K+ channel protein Kir2.1 (in ≈ 50-60% of cases). ATS type 2 is in turn linked to a rare mutation in the KCNJ5-GIRK4 gene that encodes the G protein-sensitive-activated inwardly rectifying K+ channel Kir3.4 (15%), which carries the acetylcholine-induced potassium current. About 30% of cases are de novo/sporadic, suggesting that additional as-yet unidentified genes also cause the disorder. A triad of periodic muscle paralysis, repolarization changes in the electrocardiogram, and structural body changes characterize ATS. The typical muscular change is episodic flaccid muscle weakness. Prolongation of the QU/QUc intervals and normal or minimally prolonged QT/QTc intervals with a tendency to ventricular arrhythmias are typical repolarization changes. Bidirectional ventricular tachycardia is the hallmark ventricular arrhythmia, but also premature ventricular contractions, and rarely, polymorphic ventricular tachycardia of torsade de pointes type may be present. Patients with ATS have characteristic physical developmental dysmorphisms that affect the face, skull, limbs, thorax, and stature. Mild learning difficulties and a distinct neurocognitive phenotype (deficits in executive function and abstract reasoning) have been described. About 60% of affected individuals have all features of the major triad. The purpose of this review is to present historical aspects, nomenclature (observations/criticisms), epidemiology, genetics, electrocardiography, arrhythmias, electrophysiological mechanisms, diagnostic criteria/clues of periodic paralysis, prognosis, and management of ATS.
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12
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Reilly L, Alvarado FJ, Lang D, Abozeid S, Van Ert H, Spellman C, Warden J, Makielski JC, Glukhov AV, Eckhardt LL. Genetic Loss of IK1 Causes Adrenergic-Induced Phase 3 Early Afterdepolariz ations and Polymorphic and Bidirectional Ventricular Tachycardia. Circ Arrhythm Electrophysiol 2020; 13:e008638. [PMID: 32931337 PMCID: PMC7574954 DOI: 10.1161/circep.120.008638] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/23/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND Arrhythmia syndromes associated with KCNJ2 mutations have been described clinically; however, little is known of the underlying arrhythmia mechanism. We create the first patient inspired KCNJ2 transgenic mouse and study effects of this mutation on cardiac function, IK1, and Ca2+ handling, to determine the underlying cellular arrhythmic pathogenesis. METHODS A cardiac-specific KCNJ2-R67Q mouse was generated and bred for heterozygosity (R67Q+/-). Echocardiography was performed at rest, under anesthesia. In vivo ECG recording and whole heart optical mapping of intact hearts was performed before and after adrenergic stimulation in wild-type (WT) littermate controls and R67Q+/- mice. IK1 measurements, action potential characterization, and intracellular Ca2+ imaging from isolated ventricular myocytes at baseline and after adrenergic stimulation were performed in WT and R67Q+/- mice. RESULTS R67Q+/- mice (n=17) showed normal cardiac function, structure, and baseline electrical activity compared with WT (n=10). Following epinephrine and caffeine, only the R67Q+/- mice had bidirectional ventricular tachycardia, ventricular tachycardia, frequent ventricular ectopy, and/or bigeminy and optical mapping demonstrated high prevalence of spontaneous and sustained ventricular arrhythmia. Both R67Q+/- (n=8) and WT myocytes (n=9) demonstrated typical n-shaped IK1IV relationship; however, following isoproterenol, max outward IK1 increased by ≈20% in WT but decreased by ≈24% in R67Q+/- (P<0.01). R67Q+/- myocytes (n=5) demonstrated prolonged action potential duration at 90% repolarization and after 10 nmol/L isoproterenol compared with WT (n=7; P<0.05). Ca2+ transient amplitude, 50% decay rate, and sarcoplasmic reticulum Ca2+ content were not different between WT (n=18) and R67Q+/- (n=16) myocytes. R67Q+/- myocytes (n=10) under adrenergic stimulation showed frequent spontaneous development of early afterdepolarizations that occurred at phase 3 of action potential repolarization. CONCLUSIONS KCNJ2 mutation R67Q+/- causes adrenergic-dependent loss of IK1 during terminal repolarization and vulnerability to phase 3 early afterdepolarizations. This model clarifies a heretofore unknown arrhythmia mechanism and extends our understanding of treatment implications for patients with KCNJ2 mutation.
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Affiliation(s)
- Louise Reilly
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Francisco J Alvarado
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Di Lang
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Sara Abozeid
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Hannah Van Ert
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Cordell Spellman
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Jarrett Warden
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Jonathan C Makielski
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Alexey V Glukhov
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
| | - Lee L Eckhardt
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison
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PIP 2: A critical regulator of vascular ion channels hiding in plain sight. Proc Natl Acad Sci U S A 2020; 117:20378-20389. [PMID: 32764146 PMCID: PMC7456132 DOI: 10.1073/pnas.2006737117] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP2), has long been established as a major contributor to intracellular signaling, primarily by virtue of its role as a substrate for phospholipase C (PLC). Signaling by Gq-protein-coupled receptors triggers PLC-mediated hydrolysis of PIP2 into inositol 1,4,5-trisphosphate and diacylglycerol, which are well known to modulate vascular ion channel activity. Often overlooked, however, is the role PIP2 itself plays in this regulation. Although numerous reports have demonstrated that PIP2 is critical for ion channel regulation, how it impacts vascular function has received scant attention. In this review, we focus on PIP2 as a regulator of ion channels in smooth muscle cells and endothelial cells-the two major classes of vascular cells. We further address the concerted effects of such regulation on vascular function and blood flow control. We close with a consideration of current knowledge regarding disruption of PIP2 regulation of vascular ion channels in disease.
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14
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Lv L, Zheng N, Zhang L, Li R, Li Y, Yang R, Li C, Fang R, Shabanova A, Li X, Liu Y, Liang H, Zhou Y, Shan H. Metformin ameliorates cardiac conduction delay by regulating microRNA-1 in mice. Eur J Pharmacol 2020; 881:173131. [PMID: 32450177 DOI: 10.1016/j.ejphar.2020.173131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 12/16/2022]
Abstract
Cardiac conduction delay may occur as a common complication of several cardiac diseases. A few therapies and drugs have a good effect on cardiac conduction delay. Metformin (Met) has a protective effect on the heart. This study's aim was to investigate whether Met could ameliorate cardiac conduction delay and its potential mechanism. Cardiac-specific microRNA-1 (miR-1) transgenic (TG) and myocardial infarction (MI) mouse models were used. Mice were administered with Met in an intragastric manner. We found that the expression of miR-1 was significantly up-regulated in H2O2 treated cardiomyocytes as well as in TG and MI mice. The protein levels of inwardly rectifying potassium channel 2.1 (Kir2.1) and Connexin43 (CX43) were down-regulated both in cardiomyocytes treated with H2O2 as well as cardiac tissues of TG and MI mice, as compared to their controls. Furthermore, the PR and QT intervals were prolonged, action potential duration (APD) was delayed, and conduction velocity (CV) was reduced, with upregulation of miR-1 in the hearts. In the meanwhile, intercalated disc injuries were found in the hearts of MI mice. Interestingly, Met can noticeably inhibit miR-1 upregulation and attenuate the changes mentioned above. Taken together, this suggested that Met could play an important role in improving cardiac conduction delay through inhibition of miR-1 expression. Our study proposes that Met is a potential candidate for the treatment of cardiac conduction delay and provides a new idea of treating arrhythmia with a drug.
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Affiliation(s)
- Lifang Lv
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; The Centre of Functional Experiment Teaching, Department of Basic Medicine, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Nan Zheng
- Department of Pharmacy, The Second Affiliated Hospital of Harbin Medical University (Institute of Clinical Pharmacy, The Heilongjiang Key Laboratory of Drug Research, Harbin Medical University), Harbin, China
| | - Lijia Zhang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Ruotong Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Yingnan Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Rui Yang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Chao Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Ruonan Fang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Northern Translational Medicine Research and Cooperation Center, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Azaliia Shabanova
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Northern Translational Medicine Research and Cooperation Center, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Department of Outpatient and Emergency Pediatric, Bashkir State Medical University, Ground Floor, Teatralnaya Street, 2a, 450000, Ufa, Russia
| | - Xuelian Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Yingqi Liu
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Haihai Liang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Northern Translational Medicine Research and Cooperation Center, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Yuhong Zhou
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China.
| | - Hongli Shan
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Northern Translational Medicine Research and Cooperation Center, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China.
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15
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Qiao P, Liu Y, Zhang T, Benavides A, Laganowsky A. Insight into the Selectivity of Kir3.2 toward Phosphatidylinositides. Biochemistry 2020; 59:2089-2099. [DOI: 10.1021/acs.biochem.0c00163] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Pei Qiao
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, United States
| | - Yang Liu
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Tianqi Zhang
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Amanda Benavides
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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16
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Affiliation(s)
- Lei Wu
- Department of Neurology, the Second Affiliated hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Yi Fang
- Department of Neurology, the Second Affiliated hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Bao-Rong Zhang
- Department of Neurology, the Second Affiliated hospital of Zhejiang University School of Medicine, Hangzhou, China
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17
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Lanni JS, Peal D, Ekstrom L, Chen H, Stanclift C, Bowen ME, Mercado A, Gamba G, Kahle KT, Harris MP. Integrated K+ channel and K+Cl- cotransporter functions are required for the coordination of size and proportion during development. Dev Biol 2019; 456:164-178. [PMID: 31472116 PMCID: PMC7235970 DOI: 10.1016/j.ydbio.2019.08.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 08/07/2019] [Accepted: 08/23/2019] [Indexed: 10/26/2022]
Abstract
The coordination of growth during development establishes proportionality within and among the different anatomic structures of organisms. Innate memory of this proportionality is preserved, as shown in the ability of regenerating structures to return to their original size. Although the regulation of this coordination is incompletely understood, mutant analyses of zebrafish with long-finned phenotypes have uncovered important roles for bioelectric signaling in modulating growth and size of the fins and barbs. To date, long-finned mutants identified are caused by hypermorphic mutations, leaving unresolved whether such signaling is required for normal development. We isolated a new zebrafish mutant, schleier, with proportional overgrowth phenotypes caused by a missense mutation and loss of function in the K+-Cl- cotransporter Kcc4a. Creation of dominant negative Kcc4a in wild-type fish leads to loss of growth restriction in fins and barbs, supporting a requirement for Kcc4a in regulation of proportion. Epistasis experiments suggest that Kcc4a and the two-pore potassium channel Kcnk5b both contribute to a common bioelectrical signaling response in the fin. These data suggest that an integrated bioelectric signaling pathway is required for the coordination of size and proportion during development.
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Affiliation(s)
| | - David Peal
- Department of Genetics, Harvard Medical School, Boston, MA, 02124, USA; Department of Orthopaedic Research, Boston Children's Hospital, Boston, MA, 02124, USA
| | - Laura Ekstrom
- Department of Biology, Wheaton College, Norton, MA, 02766, USA
| | - Haining Chen
- Department of Biology, Wheaton College, Norton, MA, 02766, USA
| | | | - Margot E Bowen
- Department of Genetics, Harvard Medical School, Boston, MA, 02124, USA; Department of Orthopaedic Research, Boston Children's Hospital, Boston, MA, 02124, USA
| | | | - Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico; Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Mexico
| | - Kristopher T Kahle
- Departments of Neurosurgery, Pediatrics, and Cellular & Molecular Physiology, and NIH-Rockefeller Center for Mendelian Genomics, Yale School of Medicine, New Haven, CT, 06511, USA
| | - Matthew P Harris
- Department of Genetics, Harvard Medical School, Boston, MA, 02124, USA; Department of Orthopaedic Research, Boston Children's Hospital, Boston, MA, 02124, USA
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18
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Sansone VA. Episodic Muscle Disorders. Continuum (Minneap Minn) 2019; 25:1696-1711. [PMID: 31794467 DOI: 10.1212/con.0000000000000802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE OF REVIEW This article reviews the episodic muscle disorders, including benign cramp-fasciculation syndrome, the periodic paralyses, and the nondystrophic myotonias. The core diagnostic criteria for a diagnosis of primary periodic paralysis, including clues to distinguish between the hypokalemic and hyperkalemic forms, and the distinctive elements that characterize Andersen-Tawil syndrome are discussed. Management of patients with these disorders is also discussed. RECENT FINDINGS Childhood presentations of periodic paralysis have recently been described, including atypical findings. Carbonic anhydrase inhibitors, such as dichlorphenamide, have recently been approved by the US Food and Drug Administration (FDA) for the treatment of both hypokalemic and hyperkalemic forms of periodic paralysis. Muscle MRI may be a useful outcome measure in pharmacologic trials in periodic paralysis. Genetic research continues to identify additional gene mutations responsible for periodic paralysis. SUMMARY This article will help neurologists diagnose and manage episodic muscle disorders and, in particular, the periodic paralyses and the nondystrophic myotonias.
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19
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Binda A, Rivolta I, Villa C, Chisci E, Beghi M, Cornaggia CM, Giovannoni R, Combi R. A Novel KCNJ2 Mutation Identified in an Autistic Proband Affects the Single Channel Properties of Kir2.1. Front Cell Neurosci 2018; 12:76. [PMID: 29615871 PMCID: PMC5869910 DOI: 10.3389/fncel.2018.00076] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/06/2018] [Indexed: 11/29/2022] Open
Abstract
Inwardly rectifying potassium channels (Kir) have been historically associated to several cardiovascular disorders. In particular, loss-of-function mutations in the Kir2.1 channel have been reported in cases affected by Andersen-Tawil syndrome while gain-of-function mutations in the same channel cause the short QT3 syndrome. Recently, a missense mutation in Kir2.1, as well as mutations in the Kir4.1, were reported to be involved in autism spectrum disorders (ASDs) suggesting a role of potassium channels in these diseases and introducing the idea of the existence of K+ channel ASDs. Here, we report the identification in an Italian affected family of a novel missense mutation (p.Phe58Ser) in the KCNJ2 gene detected in heterozygosity in a proband affected by autism and borderline for short QT syndrome type 3. The mutation is located in the N-terminal region of the gene coding for the Kir2.1 channel and in particular in a very conserved domain. In vitro assays demonstrated that this mutation results in an increase of the channel conductance and in its open probability. This gain-of-function of the protein is consistent with the autistic phenotype, which is normally associated to an altered neuronal excitability.
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Affiliation(s)
- Anna Binda
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Ilaria Rivolta
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Chiara Villa
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Elisa Chisci
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | | | - Cesare M Cornaggia
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Roberto Giovannoni
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Romina Combi
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
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20
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Ponce-Balbuena D, Guerrero-Serna G, Valdivia CR, Caballero R, Diez-Guerra FJ, Jiménez-Vázquez EN, Ramírez RJ, Monteiro da Rocha A, Herron TJ, Campbell KF, Willis BC, Alvarado FJ, Zarzoso M, Kaur K, Pérez-Hernández M, Matamoros M, Valdivia HH, Delpón E, Jalife J. Cardiac Kir2.1 and Na V1.5 Channels Traffic Together to the Sarcolemma to Control Excitability. Circ Res 2018. [PMID: 29514831 DOI: 10.1161/circresaha.117.311872] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE In cardiomyocytes, NaV1.5 and Kir2.1 channels interact dynamically as part of membrane bound macromolecular complexes. OBJECTIVE The objective of this study was to test whether NaV1.5 and Kir2.1 preassemble during early forward trafficking and travel together to common membrane microdomains. METHODS AND RESULTS In patch-clamp experiments, coexpression of trafficking-deficient mutants Kir2.1Δ314-315 or Kir2.1R44A/R46A with wild-type (WT) NaV1.5WT in heterologous cells reduced inward sodium current compared with NaV1.5WT alone or coexpressed with Kir2.1WT. In cell surface biotinylation experiments, expression of Kir2.1Δ314-315 reduced NaV1.5 channel surface expression. Glycosylation analysis suggested that NaV1.5WT and Kir2.1WT channels associate early in their biosynthetic pathway, and fluorescence recovery after photobleaching experiments demonstrated that coexpression with Kir2.1 increased cytoplasmic mobility of NaV1.5WT, and vice versa, whereas coexpression with Kir2.1Δ314-315 reduced mobility of both channels. Viral gene transfer of Kir2.1Δ314-315 in adult rat ventricular myocytes and human induced pluripotent stem cell-derived cardiomyocytes reduced inward rectifier potassium current and inward sodium current, maximum diastolic potential and action potential depolarization rate, and increased action potential duration. On immunostaining, the AP1 (adaptor protein complex 1) colocalized with NaV1.5WT and Kir2.1WT within areas corresponding to t-tubules and intercalated discs. Like Kir2.1WT, NaV1.5WT coimmunoprecipitated with AP1. Site-directed mutagenesis revealed that NaV1.5WT channels interact with AP1 through the NaV1.5Y1810 residue, suggesting that, like for Kir2.1WT, AP1 can mark NaV1.5 channels for incorporation into clathrin-coated vesicles at the trans-Golgi. Silencing the AP1 ϒ-adaptin subunit in human induced pluripotent stem cell-derived cardiomyocytes reduced inward rectifier potassium current, inward sodium current, and maximum diastolic potential and impaired rate-dependent action potential duration adaptation. CONCLUSIONS The NaV1.5-Kir2.1 macromolecular complex pre-assembles early in the forward trafficking pathway. Therefore, disruption of Kir2.1 trafficking in cardiomyocytes affects trafficking of NaV1.5, which may have important implications in the mechanisms of arrhythmias in inheritable cardiac diseases.
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Affiliation(s)
- Daniela Ponce-Balbuena
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Guadalupe Guerrero-Serna
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Carmen R Valdivia
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Ricardo Caballero
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.).,Instituto de Investigación Sanitaria Gregorio Marañón, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.)
| | - F Javier Diez-Guerra
- Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa (UAM-CSIC), Universidad Autónoma de Madrid, Spain (F.J.D.-G.)
| | - Eric N Jiménez-Vázquez
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Rafael J Ramírez
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - André Monteiro da Rocha
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Todd J Herron
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Katherine F Campbell
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - B Cicero Willis
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | | | - Manuel Zarzoso
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Kuljeet Kaur
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.)
| | - Marta Pérez-Hernández
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.).,Instituto de Investigación Sanitaria Gregorio Marañón, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.)
| | - Marcos Matamoros
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.).,Instituto de Investigación Sanitaria Gregorio Marañón, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.)
| | - Héctor H Valdivia
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.).,Department of Molecular and Integrative Physiology (F.J.A., H.H.V.)
| | - Eva Delpón
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.).,Instituto de Investigación Sanitaria Gregorio Marañón, School of Medicine, Universidad Complutense, Madrid, Spain (R.C., M.P.-H., M.M., E.D.)
| | - José Jalife
- From the Department of Internal Medicine and Center for Arrhythmia Research (D.P.-B., G.G.-S., C.R.V., E.N.J.-V., R.J.R., A.M.d.R., T.J.H., K.F.C., B.C.W., M.Z., K.K., H.H.V., J.J.) .,University of Michigan, Ann Arbor; Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain (J.J.).,CIBERV, Madrid, Spain (J.J.)
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21
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Abstract
The periodic paralyses are a group of skeletal muscle channelopathies characterizeed by intermittent attacks of muscle weakness often associated with altered serum potassium levels. The underlying genetic defects include mutations in genes encoding the skeletal muscle calcium channel Cav1.1, sodium channel Nav1.4, and potassium channels Kir2.1, Kir3.4, and possibly Kir2.6. Our increasing knowledge of how mutant channels affect muscle excitability has resulted in better understanding of many clinical phenomena which have been known for decades and sheds light on some of the factors that trigger attacks. Insights into the pathophysiology are also leading to new therapeutic approaches.
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Affiliation(s)
- Doreen Fialho
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Robert C Griggs
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States.
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, United Kingdom
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22
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Krych M, Biernacka EK, Ponińska J, Kukla P, Filipecki A, Gajda R, Hasdemir C, Antzelevitch C, Kosiec A, Szperl M, Płoski R, Trusz-Gluza M, Mizia-Stec K, Hoffman P. Andersen-Tawil syndrome: Clinical presentation and predictors of symptomatic arrhythmias - Possible role of polymorphisms K897T in KCNH2 and H558R in SCN5A gene. J Cardiol 2017; 70:504-510. [PMID: 28336205 DOI: 10.1016/j.jjcc.2017.01.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 12/27/2016] [Accepted: 01/12/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND Andersen-Tawil syndrome (ATS) is rare channelopathy caused by KCNJ2 mutation and probably KCNJ5. It is characterized by arrhythmias, neurological symptoms, and dysmorphic features. The present study retrospectively examined the characteristics of 11 unrelated families with ATS. METHODS This study consisted of 11 probands positive for KCNJ2 variants and 33 family members (mean age 30.0±17.3 years, female n=31). Additional genetic screening of 3 LQTS genes (KCNQ1, KCNH2, SCN5A) was performed in 9 families. Predictors of arrhythmias [premature ventricular beats>2000/24h, biventricular and polymorphic ventricular tachycardia (VT)], syncope, and/or cardiac arrest (CA) were evaluated. RESULTS In KCNJ2 mutation carriers vs non-carriers (n=25 vs n=19) significant differences were observed in U-wave manifestations in V2-V4, Tpeak-Tend duration, QTUc duration (p<0.0001), dysmorphic features, and neurological symptoms. Compared to asymptomatic carriers (n=9), in those with arrhythmias and/or syncope and/or CA (n=16) micrognathia (p=0.004), periodic paralysis (p=0.019), palpitation (p=0.005), U-wave n V2-V4 (p=0.049) were more frequent; QTU (p=0.045) and Tpeak-Tend (p=0.014) were also longer (n=9). In the subgroup of carriers with syncope and/or cardiac arrest (n=10, 90% women), K897T-KCNH2 polymorphism (p=0.02), periodic paralysis (p=0.004), muscle weakness (p=0.04), palpitations (p=0.04), arrhythmias (biventricular VT, p=0.003; polymorphic VT, p=0.009) were observed more frequently. Tpeak-Tend duration was longer (p=0.007) and the percentage of patients with premature ventricular contraction >2000/24h was higher (p=0.005). CONCLUSION A higher risk of arrhythmia, syncope, and/or CA is associated with the presence of micrognathia, periodic paralysis, and prolonged Tpeak-Tend time. Our findings suggest that K897T may contribute to the occurrence of syncope.
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Affiliation(s)
- Michalina Krych
- Department of Congenital Cardiac Defects, Institute of Cardiology, Warsaw, Poland.
| | | | - Joanna Ponińska
- Department of Molecular Biology, Institute of Cardiology, Warsaw, Poland
| | - Piotr Kukla
- Department of Cardiology and Internal Medicine, Specialistic Hospital, Gorlice, Poland
| | - Artur Filipecki
- First Department of Cardiology, School of Medicine in Katowice, Medical University of Silesia, Katowice, Poland
| | | | - Can Hasdemir
- Department of Cardiology, Ege University School of Medicine, Izmir, Turkey
| | | | - Agnieszka Kosiec
- Department of Molecular Biology, Institute of Cardiology, Warsaw, Poland
| | - Małgorzata Szperl
- Department of Molecular Biology, Institute of Cardiology, Warsaw, Poland
| | - Rafał Płoski
- Department of Medical Genetics, Warsaw Medical University, Poland
| | - Maria Trusz-Gluza
- First Department of Cardiology, School of Medicine in Katowice, Medical University of Silesia, Katowice, Poland
| | - Katarzyna Mizia-Stec
- First Department of Cardiology, School of Medicine in Katowice, Medical University of Silesia, Katowice, Poland
| | - Piotr Hoffman
- Department of Congenital Cardiac Defects, Institute of Cardiology, Warsaw, Poland
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Adams DS, Uzel SGM, Akagi J, Wlodkowic D, Andreeva V, Yelick PC, Devitt-Lee A, Pare JF, Levin M. Bioelectric signalling via potassium channels: a mechanism for craniofacial dysmorphogenesis in KCNJ2-associated Andersen-Tawil Syndrome. J Physiol 2016; 594:3245-70. [PMID: 26864374 PMCID: PMC4908029 DOI: 10.1113/jp271930] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 02/01/2016] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS Xenopus laevis craniofacial development is a good system for the study of Andersen-Tawil Syndrome (ATS)-associated craniofacial anomalies (CFAs) because (1) Kcnj2 is expressed in the nascent face; (2) molecular-genetic and biophysical techniques are available for the study of ion-dependent signalling during craniofacial morphogenesis; (3) as in humans, expression of variant Kcnj2 forms in embryos causes a muscle phenotype; and (4) variant forms of Kcnj2 found in human patients, when injected into frog embryos, cause CFAs in the same cell lineages. Forced expression of WT or variant Kcnj2 changes the normal pattern of Vmem (resting potential) regionalization found in the ectoderm of neurulating embryos, and changes the normal pattern of expression of ten different genetic regulators of craniofacial development, including markers of cranial neural crest and of placodes. Expression of other potassium channels and two different light-activated channels, all of which have an effect on Vmem , causes CFAs like those induced by injection of Kcnj2 variants. In contrast, expression of Slc9A (NHE3), an electroneutral ion channel, and of GlyR, an inactive Cl(-) channel, do not cause CFAs, demonstrating that correct craniofacial development depends on a pattern of bioelectric states, not on ion- or channel-specific signalling. Using optogenetics to control both the location and the timing of ion flux in developing embryos, we show that affecting Vmem of the ectoderm and no other cell layers is sufficient to cause CFAs, but only during early neurula stages. Changes in Vmem induced late in neurulation do not affect craniofacial development. We interpret these data as strong evidence, consistent with our hypothesis, that ATS-associated CFAs are caused by the effect of variant Kcnj2 on the Vmem of ectodermal cells of the developing face. We predict that the critical time is early during neurulation, and the critical cells are the ectodermal cranial neural crest and placode lineages. This points to the potential utility of extant, ion flux-modifying drugs as treatments to prevent CFAs associated with channelopathies such as ATS. ABSTRACT Variants in potassium channel KCNJ2 cause Andersen-Tawil Syndrome (ATS); the induced craniofacial anomalies (CFAs) are entirely unexplained. We show that KCNJ2 is expressed in Xenopus and mouse during the earliest stages of craniofacial development. Misexpression in Xenopus of KCNJ2 carrying ATS-associated mutations causes CFAs in the same structures affected in humans, changes the normal pattern of membrane voltage potential regionalization in the developing face and disrupts expression of important craniofacial patterning genes, revealing the endogenous control of craniofacial patterning by bioelectric cell states. By altering cells' resting potentials using other ion translocators, we show that a change in ectodermal voltage, not tied to a specific protein or ion, is sufficient to cause CFAs. By adapting optogenetics for use in non-neural cells in embryos, we show that developmentally patterned K(+) flux is required for correct regionalization of the resting potentials and for establishment of endogenous early gene expression domains in the anterior ectoderm, and that variants in KCNJ2 disrupt this regionalization, leading to the CFAs seen in ATS patients.
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Affiliation(s)
- Dany Spencer Adams
- Department of Biology and Tufts Centre for Regenerative and Developmental Biology, Tufts University, 200 Boston Avenue, Medford, MA, 02155, USA
| | - Sebastien G M Uzel
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - Jin Akagi
- School of Applied Sciences, RMIT University, Melbourne, Australia
| | - Donald Wlodkowic
- School of Applied Sciences, RMIT University, Melbourne, Australia
| | - Viktoria Andreeva
- Department of Orthodontics, Division of Craniofacial and Molecular Genetics, Tufts University School of Dental Medicine, Boston, MA 02111, USA
| | - Pamela Crotty Yelick
- Department of Orthodontics, Division of Craniofacial and Molecular Genetics, Tufts University School of Dental Medicine, Boston, MA 02111, USA
| | - Adrian Devitt-Lee
- Department of Biology and Tufts Centre for Regenerative and Developmental Biology, Tufts University, 200 Boston Avenue, Medford, MA, 02155, USA
| | - Jean-Francois Pare
- Department of Biology and Tufts Centre for Regenerative and Developmental Biology, Tufts University, 200 Boston Avenue, Medford, MA, 02155, USA
| | - Michael Levin
- Department of Biology and Tufts Centre for Regenerative and Developmental Biology, Tufts University, 200 Boston Avenue, Medford, MA, 02155, USA
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Malik M. Drug-Induced QT/QTc Interval Shortening: Lessons from Drug-Induced QT/QTc Prolongation. Drug Saf 2016; 39:647-59. [DOI: 10.1007/s40264-016-0411-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Spoonamore KG, Ware SM. Genetic testing and genetic counseling in patients with sudden death risk due to heritable arrhythmias. Heart Rhythm 2016; 13:789-97. [DOI: 10.1016/j.hrthm.2015.11.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Indexed: 12/16/2022]
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Effects of BKCa and Kir2.1 Channels on Cell Cycling Progression and Migration in Human Cardiac c-kit+ Progenitor Cells. PLoS One 2015; 10:e0138581. [PMID: 26390131 PMCID: PMC4577111 DOI: 10.1371/journal.pone.0138581] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Accepted: 09/01/2015] [Indexed: 12/24/2022] Open
Abstract
Our previous study demonstrated that a large-conductance Ca2+-activated K+ current (BKCa), a voltage-gated TTX-sensitive sodium current (INa.TTX), and an inward rectifier K+ current (IKir) were heterogeneously present in most of human cardiac c-kit+ progenitor cells. The present study was designed to investigate the effects of these ion channels on cell cycling progression and migration of human cardiac c-kit+ progenitor cells with approaches of cell proliferation and mobility assays, siRNA, RT-PCR, Western blots, flow cytometry analysis, etc. It was found that inhibition of BKCa with paxilline, but not INa.TTX with tetrodotoxin, decreased both cell proliferation and migration. Inhibition of IKir with Ba2+ had no effect on cell proliferation, while enhanced cell mobility. Silencing KCa.1.1 reduced cell proliferation by accumulating the cells at G0/G1 phase and decreased cell mobility. Interestingly, silencing Kir2.1 increased the cell migration without affecting cell cycling progression. These results demonstrate the novel information that blockade or silence of BKCa channels, but not INa.TTX channels, decreases cell cycling progression and mobility, whereas inhibition of Kir2.1 channels increases cell mobility without affecting cell cycling progression in human cardiac c-kit+ progenitor cells.
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Abstract
Ion channels are critical for all aspects of cardiac function, including rhythmicity and contractility. Consequently, ion channels are key targets for therapeutics aimed at cardiac pathophysiologies such as atrial fibrillation or angina. At the same time, off-target interactions of drugs with cardiac ion channels can be the cause of unwanted side effects. This manuscript aims to review the physiology and pharmacology of key cardiac ion channels. The intent is to highlight recent developments for therapeutic development, as well as elucidate potential mechanisms for drug-induced cardiac side effects, rather than present an in-depth review of each channel subtype.
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Jagodzińska M, Szperl M, Ponińska J, Kosiec A, Gajda R, Kukla P, Biernacka EK. Coexistence of Andersen-Tawil Syndrome with Polymorphisms in hERG1 Gene (K897T) and SCN5A Gene (H558R) in One Family. Ann Noninvasive Electrocardiol 2015; 21:189-95. [PMID: 26109178 DOI: 10.1111/anec.12283] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Andersen-Tawil Syndrome (ATS) is a channelopathy caused by mutations in KCNJ2 gene. It is characterized by symptoms of ventricular arrhythmias, periodic paralysis or muscle weakness, and dysmorphic features. ATS can present with the triad of symptoms, any combination or none of them. Risk factors for dangerous arrhythmias are unknown. The study assessed the impact of K897T polymorphism in hERG1 gene and H558R polymorphism in SCN5A gene coexisting with R218Q mutation in KCNJ2 in one family on clinical manifestation. METHODS Family members underwent clinical assessment, ECG and genotyping. Holter monitoring was performed in mutation carriers and additionally in one family member with no mutation, but with K897T polymorphism. RESULTS Proband with ATS mutation, K897T and H558R polymorphisms and proband's sister with ATS mutation and K897T polymorphism presented following symptoms: loss of consciousness, bidirectional and polymorphic ventricular tachycardia and about 5000 ventricular extrasystoles. Symptoms presented by the member with only the ATS mutation and by member with ATS mutation and H558R polymorphism were not as severe. U wave appeared in all examined family members regardless of the mutation presence. Studied individuals with ATS mutation had the T-peak-U-peak interval longer than 200 ms. In all ATS mutation carriers it was longer than in family members with no mutation. T-peak-T-end interval was the longest (>120 ms) in members with coexisting mutation and K897T polymorphism. CONCLUSION ATS severity possibly depends on other genes' polymorphisms. In the presented family, it could depend on the presence of K897T polymorphism in hERG1.
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Affiliation(s)
| | - Małgorzata Szperl
- Department of Molecular Biology, Institute of Cardiology, Warsaw, Poland
| | - Joanna Ponińska
- Department of Molecular Biology, Institute of Cardiology, Warsaw, Poland
| | - Agnieszka Kosiec
- Department of Molecular Biology, Institute of Cardiology, Warsaw, Poland
| | | | - Piotr Kukla
- Department of Cardiology and Internal Medicine, Specialist Hospital, Gorlice, Poland
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Fryer MD, Kaye G, Tomlinson S. Recurrent syncope in the Andersen Tawil syndrome - Cardiac or neurological? Indian Pacing Electrophysiol J 2015; 15:158-61. [PMID: 26937109 PMCID: PMC4750129 DOI: 10.1016/j.ipej.2015.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Affiliation(s)
- Michael David Fryer
- Department of Cardiology, Princess Alexandra Hospital, University of Queensland, Australia
| | - Gerald Kaye
- Department of Cardiology, Princess Alexandra Hospital, University of Queensland, Australia
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Willis BC, Ponce-Balbuena D, Jalife J. Protein assemblies of sodium and inward rectifier potassium channels control cardiac excitability and arrhythmogenesis. Am J Physiol Heart Circ Physiol 2015; 308:H1463-73. [PMID: 25862830 DOI: 10.1152/ajpheart.00176.2015] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/06/2015] [Indexed: 02/07/2023]
Abstract
The understanding of how cardiac ion channels function in the normal and the diseased heart has greatly increased over the last four decades thanks to the advent of patch-clamp technology and, more recently, the emergence of genetics, as well as cellular and molecular cardiology. However, our knowledge of how these membrane-embedded proteins physically interact with each other within macromolecular complexes remains incomplete. This review focuses on how the main cardiac inward sodium channel (NaV1.5) and the strong inward rectifier potassium channel (Kir2.1) function within macromolecular complexes to control cardiac excitability. It has become increasingly clear that these two important ion channel proteins physically interact with multiple other protein partners and with each other from early stages of protein trafficking and targeting through membrane anchoring, recycling, and degradation. Recent findings include compartmentalized regulation of NaV1.5 channel expression and function through a PDZ (postsynaptic density protein, Drosophila disc large tumor suppressor, and zonula occludens-1 protein) domain-binding motif, and interaction of caveolin-3 with Kir2.1 and ankyrin-G as a molecular platform for NaV1.5 signaling. At the cardiomyocyte membrane, NaV1.5 and Kir2.1 interact through at least two distinct PDZ domain-scaffolding proteins (synapse-associated protein-97 and α1-syntrophin), thus modulating reciprocally their cell-surface expression at two different microdomains. Emerging evidence also shows that inheritable mutations in plakophilin-2, ankyrin-G, dystrophin, syntrophin, synapse-associated protein-97, and caveolin-3, among others, modify functional expression and/or localization in the cardiac cell of NaV1.5, Kir2.1 or both to give rise to arrhythmogenic diseases. Unveiling the mechanistic underpinnings of macromolecular interactions should increase our understanding of inherited and acquired arrhythmogenic cardiac diseases and may lead to advances in therapy.
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Affiliation(s)
- B Cicero Willis
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan; and
| | - Daniela Ponce-Balbuena
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan; and
| | - José Jalife
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan; and Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
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Miyamoto K, Aiba T, Kimura H, Hayashi H, Ohno S, Yasuoka C, Tanioka Y, Tsuchiya T, Yoshida Y, Hayashi H, Tsuboi I, Nakajima I, Ishibashi K, Okamura H, Noda T, Ishihara M, Anzai T, Yasuda S, Miyamoto Y, Kamakura S, Kusano K, Ogawa H, Horie M, Shimizu W. Efficacy and safety of flecainide for ventricular arrhythmias in patients with Andersen-Tawil syndrome with KCNJ2 mutations. Heart Rhythm 2015; 12:596-603. [DOI: 10.1016/j.hrthm.2014.12.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Indexed: 11/24/2022]
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Dascal N, Kahanovitch U. The Roles of Gβγ and Gα in Gating and Regulation of GIRK Channels. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:27-85. [DOI: 10.1016/bs.irn.2015.06.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Mutational Consequences of Aberrant Ion Channels in Neurological Disorders. J Membr Biol 2014; 247:1083-127. [DOI: 10.1007/s00232-014-9716-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 07/25/2014] [Indexed: 12/25/2022]
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Kukla P, Biernacka EK, Baranchuk A, Jastrzebski M, Jagodzinska M. Electrocardiogram in Andersen-Tawil syndrome. New electrocardiographic criteria for diagnosis of type-1 Andersen-Tawil syndrome. Curr Cardiol Rev 2014; 10:222-8. [PMID: 24827800 PMCID: PMC4040873 DOI: 10.2174/1573403x10666140514102528] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 06/10/2013] [Accepted: 01/28/2014] [Indexed: 11/22/2022] Open
Abstract
Andersen - Tawil syndrome (ATS) is an autosomal - dominant or sporadic disorder characterized by ventricular arrhythmias, periodic paralysis, and distinctive facial and skeletal dysmorphism. Mutations in KCNJ2, which encodes the α-subunit of the potassium channel Kir2.1, were identified in patients with ATS. This genotype has been designated as type-1 ATS (ATS1). KCNJ2 mutations are detectable in up to 60 % of patients with ATS. Cardiac manifestations of ATS include frequent premature ventricular contractions (PVC), Q-U interval prolongation, prominent U-waves, and a special type of polymorphic ventricular tachycardia (PMVT) called bidirectional ventricular tachycardia (BiVT). The presence of frequent PVCs at rest are helpful in distinguishing ATS from typical catecholaminergic polymorphic ventricular tachycardia (CPVT). In typical CPVT, rapid PMVT and BiVT usually manifest during or after exercising. Additionally, CPVT or torsade de pointes in LQTS are faster, very symptomatic causing syncope or often deteriorate into VF resulting in sudden cardiac death. PVCs at rest are quite frequent in ATS1 patients, however, in LQTS patients, PVCs and asymptomatic VT are uncommon which also contributes to differentiating them. The article describes the new electrocardiographic criteria proposed for diagnosis of type-1 Andersen-Tawil syndrome. A differential diagnosis between Andersen-Tawil syndrome, the catecholamine polymorphic ventiruclar tachycardia and long QT syndrome is depicted. Special attention is paid on the repolarization abnormalities, QT interval and the pathologic U wave. In this article, we aim to provide five new electrocardiographic clues for the diagnosis of ATS1.
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Affiliation(s)
| | | | | | | | - Michalina Jagodzinska
- Department of Cardiology and Internal Medicine, Specialistic Hospital, Gorlice, Poland, 38-300 Gorlice, Wegierska Street 21, Poland.
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Dhamija R, Bodensteiner JB. Recurrent episodes of weak spells in a 15-year-old boy. Semin Pediatr Neurol 2014; 21:91-4. [PMID: 25149934 DOI: 10.1016/j.spen.2014.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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KCNJ2 mutation causes an adrenergic-dependent rectification abnormality with calcium sensitivity and ventricular arrhythmia. Heart Rhythm 2014; 11:885-94. [PMID: 24561538 DOI: 10.1016/j.hrthm.2014.02.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Indexed: 11/23/2022]
Abstract
BACKGROUND KCNJ2 mutations are associated with a variety of inherited arrhythmia syndromes including catecholaminergic polymorphic ventricular tachycardia 3. OBJECTIVE To characterize the detailed cellular mechanisms of the clinically recognized KCNJ2 mutation R67Q. METHODS Kir2.1 current density was measured from COS-1 cells transiently transfected with wild-type human Kir-2.1 (WT-Kir2.1) and/or a heterozygous missense mutation in KCNJ2 (R67Q-Kir2.1) by using the whole-cell voltage clamp technique. Catecholamine activity was simulated with protein kinase A-stimulating cocktail exposure. Phosphorylation-deficient mutants, S425N-Kir2.1 and S425N-Kir2.1/R67Q-S425N-Kir2.1, were used in a separate set of experiments. HA- or Myc-Tag-WT-Kir2.1 and HA-Tag-R67Q-Kir2.1 were used for confocal imaging. RESULTS A 33-year-old woman presented with a catecholaminergic polymorphic ventricular tachycardia-like clinical phenotype and was found to have KCNJ2 missense mutation R67Q. Treatment with nadolol and flecainide resulted in the complete suppression of arrhythmias and symptom resolution. Under baseline conditions, R67Q-Kir2.1 expressed alone did not produce inward rectifier current while cells coexpressing WT-Kir2.1 and R67Q-Kir2.1 demonstrated the rectification index (RI) similar to that of WT-Kir2.1. After PKA stimulation, R67Q-Kir2.1/WT-Kir2.1 failed to increase peak outward current density; WT-Kir2.1 increased by 46% (n = 5), while R67Q-Kir2.1/WT-Kir2.1 decreased by 6% (n = 6) (P = .002). Rectification properties in R67Q-Kir2.1/WT-Kir2.1 demonstrated sensitivity to calcium with a decreased RI in the high-calcium pipette solution (RI 20.3% ± 4.1%) than in the low-calcium pipette solution (RI 36.5% ± 5.7%) (P < .05). Immunostaining of WT-Kir2.1 and R67Q-Kir2.1 individually and together showed a normal membrane expression pattern and colocalization by using the Pearson correlation coefficient. CONCLUSIONS R67Q-Kir2.1 is associated with an adrenergic-dependent clinical and cellular phenotype with rectification abnormality enhanced by increased calcium. These findings are a significant advancement of our knowledge and understanding of the phenotype-genotype relationship of arrhythmia syndromes related to KCNJ2 mutations.
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Abstract
Saccadic oscillations are continuous back-to-back saccades that cause excessive image motion across fovea and threaten clear vision. Acquired processes, related to immune or metabolic mechanisms, are common culprits. Saccadic oscillations are also seen in degenerative cerebellar disease or as a part of a familial syndrome of saccadic oscillations and limb tremor. Some normal individuals have innate ability to voluntarily trigger saccadic oscillations (i.e. voluntary nystagmus). Contemporary theory for the pathogenesis for saccadic oscillations has emphasized hyperexcitable or disinhibited state of the brainstem saccadic burst neuron membrane. This review discusses etiologies and treatment of saccadic oscillations in light of novel cell membrane based theory.
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Affiliation(s)
- Aasef G Shaikh
- Department of Neurology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH
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Abstract
INTRODUCTION Skeletal muscle channelopathies are rare disorders of muscle membrane excitability. Their episodic nature may result in diagnostic difficulty and delays in diagnosis. Advances in diagnostic clinical electrophysiology combined with DNA-based diagnosis have improved diagnostic accuracy and efficiency. Ascribing pathogenic status to identified genetic variants in muscle channel genes may be complex and functional analysis, including molecular expression, may help with this. Accurate clinical and genetic diagnosis enables genetic counselling, advice regarding prognosis and aids treatment selection. AREAS COVERED An approach to accurate and efficient diagnosis is outlined. The importance of detailed clinical evaluation including careful history, examination and family history is emphasised. The role of specialised electrodiagnostics combined with DNA testing and molecular expression is considered. New potential biomarkers including muscle MRI using MRC Centre protocols are discussed. EXPERT OPINION A combined diagnostic approach using careful clinical assessment, specialised neurophysiology and DNA testing will now achieve a clear diagnosis in most patients with muscle channelopathies. An accurate diagnosis enables genetic counselling and provides information regarding prognosis and treatment selection. Genetic analysis often identifies new variants of uncertain significance. In this situation, functional expression studies as part of a diagnostic service will enable determination of pathogenic status of novel genetic variants.
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Affiliation(s)
- Jennifer Spillane
- UCL, Institute of Neurology, MRC Centre for Neuromuscular Diseases , Queen Square, London, WC1N3BG UK ,
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40
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Horga A, Raja Rayan DL, Matthews E, Sud R, Fialho D, Durran SCM, Burge JA, Portaro S, Davis MB, Haworth A, Hanna MG. Prevalence study of genetically defined skeletal muscle channelopathies in England. Neurology 2013; 80:1472-5. [PMID: 23516313 DOI: 10.1212/wnl.0b013e31828cf8d0] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES To obtain minimum point prevalence rates for the skeletal muscle channelopathies and to evaluate the frequency distribution of mutations associated with these disorders. METHODS Analysis of demographic, clinical, electrophysiologic, and genetic data of all patients assessed at our national specialist channelopathy service. Only patients living in the United Kingdom with a genetically defined diagnosis of nondystrophic myotonia or periodic paralysis were eligible for the study. Prevalence rates were estimated for England, December 2011. RESULTS A total of 665 patients fulfilled the inclusion criteria, of which 593 were living in England, giving a minimum point prevalence of 1.12/100,000 (95% confidence interval [CI] 1.03-1.21). Disease-specific prevalence figures were as follows: myotonia congenita 0.52/100,000 (95% CI 0.46-0.59), paramyotonia congenita 0.17/100,000 (95% CI 0.13-0.20), sodium channel myotonias 0.06/100,000 (95% CI 0.04-0.08), hyperkalemic periodic paralysis 0.17/100,000 (95% CI 0.13-0.20), hypokalemic periodic paralysis 0.13/100,000 (95% CI 0.10-0.17), and Andersen-Tawil syndrome (ATS) 0.08/100,000 (95% CI 0.05-0.10). In the whole sample (665 patients), 15 out of 104 different CLCN1 mutations accounted for 60% of all patients with myotonia congenita, 11 out of 22 SCN4A mutations for 86% of paramyotonia congenita/sodium channel myotonia pedigrees, and 3 out of 17 KCNJ2 mutations for 42% of ATS pedigrees. CONCLUSION We describe for the first time the overall prevalence of genetically defined skeletal muscle channelopathies in England. Despite the large variety of mutations observed in patients with nondystrophic myotonia and ATS, a limited number accounted for a large proportion of cases.
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Affiliation(s)
- Alejandro Horga
- Medical Research Council Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery and University College London Institute of Neurology, Queen Square, London, UK
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Modoni A, Bianchi MLE, Vitulano N, Pagliarani S, Perna F, Sanna T, Rizzo V, Silvestri G. Lack of Any Cardiac Involvement in a Patient with Andersen-Tawil Syndrome Associated with the c.574A→G Mutation in KCNJ2. Cardiology 2012; 120:200-3. [DOI: 10.1159/000335529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/05/2011] [Indexed: 11/19/2022]
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Pattnaik BR, Asuma MP, Spott R, Pillers DAM. Genetic defects in the hotspot of inwardly rectifying K(+) (Kir) channels and their metabolic consequences: a review. Mol Genet Metab 2012; 105:64-72. [PMID: 22079268 PMCID: PMC3253982 DOI: 10.1016/j.ymgme.2011.10.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 10/11/2011] [Accepted: 10/12/2011] [Indexed: 02/07/2023]
Abstract
Inwardly rectifying potassium (Kir) channels are essential for maintaining normal potassium homeostasis and the resting membrane potential. As a consequence, mutations in Kir channels cause debilitating diseases ranging from cardiac failure to renal, ocular, pancreatic, and neurological abnormalities. Structurally, Kir channels consist of two trans-membrane domains, a pore-forming loop that contains the selectivity filter and two cytoplasmic polar tails. Within the cytoplasmic structure, clusters of amino acid sequences form regulatory domains that interact with cellular metabolites to control the opening and closing of the channel. In this review, we present an overview of Kir channel function and recent progress in the characterization of selected Kir channel mutations that lie in and near a C-terminal cytoplasmic 'hotspot' domain. The resultant molecular mechanisms by which the loss or gain of channel function leads to organ failure provide potential opportunities for targeted therapeutic interventions for this important group of channelopathies.
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Affiliation(s)
- Bikash R. Pattnaik
- Department of Pediatrics, University of Wisconsin, Madison
- Department of Ophthalmology & Visual Sciences, University of Wisconsin, Madison
- Department of Eye Research Institute, University of Wisconsin, Madison
| | - Matti P. Asuma
- Department of Pediatrics, University of Wisconsin, Madison
| | - Ryan Spott
- Department of Pediatrics, University of Wisconsin, Madison
| | - De-Ann M. Pillers
- Department of Pediatrics, University of Wisconsin, Madison
- Department of Eye Research Institute, University of Wisconsin, Madison
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Ma D, Taneja TK, Hagen BM, Kim BY, Ortega B, Lederer WJ, Welling PA. Golgi export of the Kir2.1 channel is driven by a trafficking signal located within its tertiary structure. Cell 2011; 145:1102-15. [PMID: 21703452 PMCID: PMC3139129 DOI: 10.1016/j.cell.2011.06.007] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 02/04/2011] [Accepted: 06/06/2011] [Indexed: 10/18/2022]
Abstract
Mechanisms that are responsible for sorting newly synthesized proteins for traffic to the cell surface from the Golgi are poorly understood. Here, we show that the potassium channel Kir2.1, mutations in which are associated with Andersen-Tawil syndrome, is selected as cargo into Golgi export carriers in an unusual signal-dependent manner. Unlike conventional trafficking signals, which are typically comprised of short linear peptide sequences, Golgi exit of Kir2.1 is dictated by residues that are embedded within the confluence of two separate domains. This signal patch forms a recognition site for interaction with the AP1 adaptor complex, thereby marking Kir2.1 for incorporation into clathrin-coated vesicles at the trans-Golgi. The identification of a trafficking signal in the tertiary structure of Kir2.1 reveals a quality control step that couples protein conformation to Golgi export and provides molecular insight into how mutations in Kir2.1 arrest the channels at the Golgi.
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Affiliation(s)
| | | | - Brian M. Hagen
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD 21201
| | - Bo-Young Kim
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD 21201
| | - Bernardo Ortega
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD 21201
| | - W. Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD 21201
| | - Paul A. Welling
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD 21201
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Barajas-Martinez H, Hu D, Ontiveros G, Caceres G, Desai M, Burashnikov E, Scaglione J, Antzelevitch C. Biophysical and molecular characterization of a novel de novo KCNJ2 mutation associated with Andersen-Tawil syndrome and catecholaminergic polymorphic ventricular tachycardia mimicry. ACTA ACUST UNITED AC 2010; 4:51-7. [PMID: 21148745 DOI: 10.1161/circgenetics.110.957696] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mutations in KCNJ2, the gene encoding the human inward rectifier potassium channel Kir2.1 (IK1 or IKir2.1), have been identified in Andersen-Tawil syndrome. Andersen-Tawil syndrome is a multisystem inherited disease exhibiting periodic paralysis, cardiac arrhythmias, and dysmorphic features at times mimicking catecholaminergic polymorphic ventricular tachycardia. METHODS AND RESULTS Our proband displayed dysmorphic features including micrognathia, clinodactyly, and syndactyly and exhibited multiform extrasystoles and bidirectional ventricular tachycardia both at rest and during exercise testing. The patient's symptoms continued after administration of nadolol but subsided after treatment with flecainide. Molecular genetic screening revealed a novel heterozygous mutation (c.779G>C/p.R260P) in KCNJ2. Whole-cell patch-clamp studies conducted in TSA201 cells transfected with wild-type human KCNJ2 cDNA (WT-KCNJ2) yielded robust IKir2.1 but no measurable current in cells expressing the R260P mutant. Coexpression of WT and R260P-KCNJ2 (heterozygous expression) yielded a markedly reduced inward IKir2.1 compared with WT alone (-36.5±9.8 pA/pF versus -143.5±11.4 pA/pF, n=8 for both, P<0.001, respectively, at -90 mV), indicating a strong dominant negative effect of the mutant. The outward component of IKir2.1 measured at -50 mV was also markedly reduced with the heterozygous expression versus WT (0.52±5.5 pA/pF versus 23.4±6.7 pA/pF, n=8 for both, P<0.001, respectively). Immunocytochemical analysis indicates that impaired trafficking of R260P-KCNJ2 channels. CONCLUSIONS We report a novel de novo KCNJ2 mutation associated with classic phenotypic features of Andersen-Tawil syndrome and catecholaminergic polymorphic ventricular tachycardia mimicry. The R260P mutation produces a strong dominant negative effect leading to marked suppression of IK1 secondary to a trafficking defect.
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Abstract
Inherited episodic neurological disorders are often due to mutations in ion channels or their interacting proteins, termed channelopathies. There are a wide variety of such disorders, from those causing paralysis, to extreme pain, to ataxia. A common theme in these is alteration of action potential properties or synaptic transmission and a resulting increased propensity of the resulting tissue to enter into or stay in an altered excitability state. Manifestations of these disorders are triggered by an array of precipitants, all of which stress the particular affected tissue in some way and aid in propelling its activity into an aberrant state. Study of these disorders has aided in the understanding of disease risk factors and elucidated the cause of clinically related sporadic disorders. The findings from study of these disorders will aid in the diagnosis and efficient targeted treatment of affected patients.
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Affiliation(s)
- Devon P Ryan
- Neuroscience Graduate Program, University of California-San Francisco, San Francisco, CA 94158, USA
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47
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Hypokalemic thyrotoxic periodic paralysis with thyrotoxic psychosis and hypercapnic respiratory failure. Am J Med Sci 2010; 340:147-53. [PMID: 20581656 DOI: 10.1097/maj.0b013e3181cbf567] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Thyrotoxic periodic paralysis is a rare and potentially lethal neuromuscular disease that manifests as recurrent episodic muscle weakness associated with hypokalemia and thyrotoxicosis. Paralysis can rarely involve respiratory muscles leading to acute respiratory failure. The disease primarily affects people of Asian descent, but it is being increasingly reported in other ethnic groups. We review the literature and report a case of hypokalemic thyrotoxic periodic paralysis manifesting as thyroid storm with episodic acute respiratory failure requiring recurrent intubation and eventually requiring thyroidectomy for resolution of symptoms.
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de Boer TP, Houtman MJC, Compier M, van der Heyden MAG. The mammalian K(IR)2.x inward rectifier ion channel family: expression pattern and pathophysiology. Acta Physiol (Oxf) 2010; 199:243-56. [PMID: 20331539 DOI: 10.1111/j.1748-1716.2010.02108.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Inward rectifier currents based on K(IR)2.x subunits are regarded as essential components for establishing a stable and negative resting membrane potential in many excitable cell types. Pharmacological inhibition, null mutation in mice and dominant positive and negative mutations in patients reveal some of the important functions of these channels in their native tissues. Here we review the complex mammalian expression pattern of K(IR)2.x subunits and relate these to the outcomes of functional inhibition of the resultant channels. Correlations between expression and function in muscle and bone tissue are observed, while we recognize a discrepancy between neuronal expression and function.
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Affiliation(s)
- T P de Boer
- Department of Medical Physiology, UMCU, Utrecht, the Netherlands
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Lim BC, Kim GB, Bae EJ, Noh CI, Hwang H, Kim KJ, Hwang YS, Ko TS, Chae JH. Andersen cardiodysrhythmic periodic paralysis with KCNJ2 mutations: a novel mutation in the pore selectivity filter residue. J Child Neurol 2010; 25:490-3. [PMID: 20382953 DOI: 10.1177/0883073809357937] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Andersen cardiodysrhythmic periodic paralysis or Andersen-Tawil syndrome includes the distinct clinical features of periodic paralysis, cardiac arrhythmia, and facial and skeletal dysmorphisms and exhibits autosomal dominant inheritance. Mutations in the KCNJ2 gene, which encodes the human inward rectifier potassium channel Kir2.1, have been identified in the majority of cases. Despite well-established clinical and molecular characteristics, treatment is still case oriented, and timely diagnosis could be delayed because of the low incidence and phenotypic heterogeneity of this disease. This article describes the clinical and molecular features of 3 cases of Andersen-Tawil syndrome in 2 families. One of the mutations (G144D) was located in the pore selectivity filter residue (which is mutated recurrently) and was considered novel. Intermittent muscle weakness in childhood warrants careful evaluation of cardiac dysrhythmia and skeletal anomalies.
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Affiliation(s)
- Byung Chan Lim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea
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