951
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Abstract
Drug-induced long QT syndrome is a cardiac safety issue that all drugs seeking approval must currently address, in part via in vitro electrophysiological testing of the drug's effects on the function of the human Ether-à-go-go Related Gene (hERG) potassium channel. This regulatory strategy has also been scientifically successful, in that these in vitro assays are cheaper and faster than are many other surrogates for arrhythmogenic risk, including QT prolongation in humans and action potential prolongation in cardiomyocytes. In some ways hERG assays are also more sensitive to the underlying repolarization anomalies that lead to the risk of the Torsades de pointes arrhythmia. In addition, the higher throughput of hERG assays combined with advances in our understanding of the molecular structures underlying this pathophysiology have led to new approaches in the medicinal chemistry of "designing out" hERG liability from lead compounds. While generally effectual, hERG screening produces some false positives: drugs with an apparent liability that are known not to be clinically arrhythmogenic. New technologies continue to be developed to improve hERG screening, while further insights into the molecular pharmacology of hERG and cardiac repolarization are providing avenues to mitigate and make sense of the lack of torsadogenic specificity in extant hERG assays.
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Affiliation(s)
- Harry J Witchel
- Medical Research Building, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK.
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952
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Ganapathi SB, Fox TE, Kester M, Elmslie KS. Ceramide modulates HERG potassium channel gating by translocation into lipid rafts. Am J Physiol Cell Physiol 2010; 299:C74-86. [PMID: 20375276 DOI: 10.1152/ajpcell.00462.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Human ether-à-go-go-related gene (HERG) potassium channels play an important role in cardiac action potential repolarization, and HERG dysfunction can cause cardiac arrhythmias. However, recent evidence suggests a role for HERG in the proliferation and progression of multiple types of cancers, making it an attractive target for cancer therapy. Ceramide is an important second messenger of the sphingolipid family, which due to its proapoptotic properties has shown promising results in animal models as an anticancer agent. Yet the acute effects of ceramide on HERG potassium channels are not known. In the present study we examined the effects of cell-permeable C(6)-ceramide on HERG potassium channels stably expressed in HEK-293 cells. C(6)-ceramide (10 microM) reversibly inhibited HERG channel current (I(HERG)) by 36 +/- 5%. Kinetically, ceramide induced a significant hyperpolarizing shift in the current-voltage relationship (DeltaV(1/2) = -8 +/- 0.5 mV) and increased the deactivation rate (43 +/- 3% for tau(fast) and 51 +/- 3% for tau(slow)). Mechanistically, ceramide recruited HERG channels within caveolin-enriched lipid rafts. Cholesterol depletion and repletion experiments and mathematical modeling studies confirmed that inhibition and gating effects are mediated by separate mechanisms. The ceramide-induced hyperpolarizing gating shift (raft mediated) could offset the impact of inhibition (raft independent) during cardiac action potential repolarization, so together they may nullify any negative impact on cardiac rhythm. Our results provide new insights into the effects of C(6)-ceramide on HERG channels and suggest that C(6)-ceramide can be a promising therapeutic for cancers that overexpress HERG.
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Affiliation(s)
- Sindura B Ganapathi
- Department of Pharmacology, Pennsylvania State College of Medicine, Hershey, PA 17033, USA
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953
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Protein Binding-dependent Decreases in hERG Channel Blocker Potency Assessed by Whole-Cell Voltage Clamp in Serum. J Cardiovasc Pharmacol 2010; 55:368-76. [DOI: 10.1097/fjc.0b013e3181d2ce39] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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954
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Thermosensitive TRP channel pore turret is part of the temperature activation pathway. Proc Natl Acad Sci U S A 2010; 107:7083-8. [PMID: 20351268 DOI: 10.1073/pnas.1000357107] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Temperature sensing is crucial for homeotherms, including human beings, to maintain a stable body core temperature and respond to the ambient environment. A group of exquisitely temperature-sensitive transient receptor potential channels, termed thermoTRPs, serve as cellular temperature sensors. How thermoTRPs convert thermal energy (heat) into protein conformational changes leading to channel opening remains unknown. Here we demonstrate that the pathway for temperature-dependent activation is distinct from those for ligand- and voltage-dependent activation and involves the pore turret. We found that mutant channels with an artificial pore turret sequence lose temperature sensitivity but maintain normal ligand responses. Using site-directed fluorescence recordings we observed that temperature change induces a significant rearrangement of TRPV1 pore turret that is coupled to channel opening. This movement is specifically associated to temperature-dependent activation and is not observed during ligand- and voltage-dependent channel activation. These observations suggest that the turret is part of the temperature-sensing apparatus in thermoTRP channels, and its conformational change may give rise to the large entropy that defines high temperature sensitivity.
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955
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Doddareddy M, Klaasse E, Shagufta, IJzerman A, Bender A. Prospective Validation of a Comprehensive In silico hERG Model and its Applications to Commercial Compound and Drug Databases. ChemMedChem 2010; 5:716-29. [DOI: 10.1002/cmdc.201000024] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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956
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Guo J, Han SN, Liu JX, Zhang XM, Hu ZS, Shi J, Zhang LR, Zhao ZZ, Zhang Z. The Action of a Novel Fluoroquinolone Antibiotic Agent Antofloxacin Hydrochloride on Human-Ether-à-go-go-Related Gene Potassium Channel. Basic Clin Pharmacol Toxicol 2010; 107:643-9. [DOI: 10.1111/j.1742-7843.2010.00550.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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957
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Abstract
With the ever increasing volume of data available to scientists in drug discovery and development, the opportunity to leverage an increasing amount of these data in the assessment of drug safety is clear. The challenge in an environment of increasing data volume is in the structuring and the analysis of these data, such that decisions can be made without excluding information or overstating their meaning. Informatics and modelling play a crucial role in addressing this challenge in two basic ways: a) the data are structured and analysed in a transparent and objective way; and b) new experiments are designed with the model as part of the design process, much like modern experimental physics. Enhancing the use and impact of informatics and modelling on drug discovery is not simply a matter of increasing processor speed and memory capacity. The transformation of raw data to usable, and useful, information is a scientific, technical and, perhaps most importantly, cultural challenge within drug discovery. This review will highlight some of the history, current approaches and promising future directions in this rapidly expanding area.
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Affiliation(s)
- Scott Boyer
- Global Safety Assessment, AstraZeneca R&D, Mölndal, Sweden.
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958
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Kim IM, Wolf MJ, Rockman HA. Gene deletion screen for cardiomyopathy in adult Drosophila identifies a new notch ligand. Circ Res 2010; 106:1233-43. [PMID: 20203305 DOI: 10.1161/circresaha.109.213785] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
RATIONALE Drosophila has been recognized as a model to study human cardiac diseases. OBJECTIVE Despite these findings, and the wealth of tools that are available to the fly community, forward genetic screens for adult heart phenotypes have been rarely performed because of the difficulty in accurately measuring cardiac function in adult Drosophila. METHODS AND RESULTS Using optical coherence tomography to obtain real-time analysis of cardiac function in awake Drosophila, we performed a genomic deficiency screen in adult flies. Based on multiple complementary approaches, we identified CG31665 as a novel gene causing dilated cardiomyopathy. CG31665, which we name weary (wry), has structural similarities to members of the Notch family. Using cell aggregation assays and gamma-secretase inhibitors we show that Wry is a novel Notch ligand that can mediate cellular adhesion with Notch expressing cells and transactivates Notch to promote signaling and nuclear transcription. Importantly, Wry lacks a DSL (Delta-Serrate-Lag) domain that is common feature to the other Drosophila Notch ligands. We further show that Notch signaling is critically important for the maintenance of normal heart function of the adult fly. CONCLUSIONS In conclusion, we identify a previously unknown Notch ligand in Drosophila that when deleted causes cardiomyopathy. Our study suggests that Notch signaling components may be a therapeutic target for dilated cardiomyopathy.
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Affiliation(s)
- Il-Man Kim
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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959
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Ahrens-Nicklas RC, Christini DJ. Anthropomorphizing the mouse cardiac action potential via a novel dynamic clamp method. Biophys J 2010; 97:2684-92. [PMID: 19917221 DOI: 10.1016/j.bpj.2009.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 08/21/2009] [Accepted: 09/01/2009] [Indexed: 11/29/2022] Open
Abstract
Interspecies differences can limit the translational value of excitable cells isolated from model organisms. It can be difficult to extrapolate from a drug- or mutation-induced phenotype in mice to human pathophysiology because mouse and human cardiac electrodynamics differ greatly. We present a hybrid computational-experimental technique, the cell-type transforming clamp, which is designed to overcome such differences by using a calculated compensatory current to convert the macroscopic electrical behavior of an isolated cell into that of a different cell type. We demonstrate the technique's utility by evaluating drug arrhythmogenicity in murine cardiomyocytes that are transformed to behave like human myocytes. Whereas we use the cell-type transforming clamp in this work to convert between mouse and human electrodynamics, the technique could be adapted to convert between the action potential morphologies of any two cell types of interest.
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960
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Roelfsema MRG, Hedrich R. Making sense out of Ca(2+) signals: their role in regulating stomatal movements. PLANT, CELL & ENVIRONMENT 2010; 33:305-321. [PMID: 19906147 DOI: 10.1111/j.1365-3040.2009.02075.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Plant cells maintain high Ca(2+) concentration gradients between the cytosol and the extracellular matrix, as well as intracellular compartments. During evolution, the regulatory mechanisms, maintaining low cytosolic free Ca(2+) concentrations, most likely provided the backbone for the development of Ca(2+)-dependent signalling pathways. In this review, the current understanding of molecular mechanisms involved in Ca(2+) homeostasis of plants cells is evaluated. The question is addressed to which extent the mechanisms, controlling the cytosolic Ca(2+) concentration, are linked to Ca(2+)-based signalling. A large number of environmental stimuli can evoke Ca(2+) signals, but the Ca(2+)-induced responses are likely to differ depending on the stimulus applied. Two mechanisms are put forward to explain signal specificity of Ca(2+)-dependent responses. A signal may evoke a specific Ca(2+) signature that is recognized by downstream signalling components. Alternatively, Ca(2+) signals are accompanied by Ca(2+)-independent signalling events that determine the specificity of the response. The existence of such parallel-acting pathways explains why guard cell responses to abscisic acid (ABA) can occur in the absence, as well as in the presence, of Ca(2+) signals. Future research may shed new light on the relation between parallel acting Ca(2+)-dependent and -independent events, and may provide insights in their evolutionary origin.
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Affiliation(s)
- M Rob G Roelfsema
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany.
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961
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Thai KM, Windisch A, Stork D, Weinzinger A, Schiesaro A, Guy R, Timin E, Hering S, Ecker G. The hERG Potassium Channel and Drug Trapping: Insight from Docking Studies with Propafenone Derivatives. ChemMedChem 2010; 5:436-42. [DOI: 10.1002/cmdc.200900374] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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962
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Grunnet M. Repolarization of the cardiac action potential. Does an increase in repolarization capacity constitute a new anti-arrhythmic principle? Acta Physiol (Oxf) 2010; 198 Suppl 676:1-48. [PMID: 20132149 DOI: 10.1111/j.1748-1716.2009.02072.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The cardiac action potential can be divided into five distinct phases designated phases 0-4. The exact shape of the action potential comes about primarily as an orchestrated function of ion channels. The present review will give an overview of ion channels involved in generating the cardiac action potential with special emphasis on potassium channels involved in phase 3 repolarization. In humans, these channels are primarily K(v)11.1 (hERG1), K(v)7.1 (KCNQ1) and K(ir)2.1 (KCNJ2) being the responsible alpha-subunits for conducting I(Kr), I(Ks) and I(K1). An account will be given about molecular components, biophysical properties, regulation, interaction with other proteins and involvement in diseases. Both loss and gain of function of these currents are associated with different arrhythmogenic diseases. The second part of this review will therefore elucidate arrhythmias and subsequently focus on newly developed chemical entities having the ability to increase the activity of I(Kr), I(Ks) and I(K1). An evaluation will be given addressing the possibility that this novel class of compounds have the ability to constitute a new anti-arrhythmic principle. Experimental evidence from in vitro, ex vivo and in vivo settings will be included. Furthermore, conceptual differences between the short QT syndrome and I(Kr) activation will be accounted for.
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Affiliation(s)
- M Grunnet
- NeuroSearch A/S, Ballerup, and Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Denmark.
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963
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Agarwal JR, Griesinger F, Stühmer W, Pardo LA. The potassium channel Ether à go-go is a novel prognostic factor with functional relevance in acute myeloid leukemia. Mol Cancer 2010; 9:18. [PMID: 20105281 PMCID: PMC2835655 DOI: 10.1186/1476-4598-9-18] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Accepted: 01/27/2010] [Indexed: 11/16/2022] Open
Abstract
Background The voltage-gated potassium channel hEag1 (KV10.1) has been related to cancer biology. The physiological expression of the human channel is restricted to the brain but it is frequently and abundantly expressed in many solid tumors, thereby making it a promising target for a specific diagnosis and therapy. Because chronic lymphatic leukemia has been described not to express hEag1, it has been assumed that the channel is not expressed in hematopoietic neoplasms in general. Results Here we show that this assumption is not correct, because the channel is up-regulated in myelodysplastic syndromes, chronic myeloid leukemia and almost half of the tested acute myeloid leukemias in a subtype-dependent fashion. Most interestingly, channel expression strongly correlated with increasing age, higher relapse rates and a significantly shorter overall survival. Multivariate Cox regression analysis revealed hEag1 expression levels in AML as an independent predictive factor for reduced disease-free and overall survival; such an association had not been reported before. As a functional correlate, specific hEag1 blockade inhibited the proliferation and migration of several AML cell lines and primary cultured AML cells in vitro. Conclusion Our observations implicate hEag1 as novel target for diagnostic, prognostic and/or therapeutic approaches in AML.
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Affiliation(s)
- Jasmin R Agarwal
- Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Str, 3, 37075 Göttingen, Germany
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964
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Gessner G, Macianskiene R, Starkus JG, Schönherr R, Heinemann SH. The amiodarone derivative KB130015 activates hERG1 potassium channels via a novel mechanism. Eur J Pharmacol 2010; 632:52-9. [PMID: 20097192 DOI: 10.1016/j.ejphar.2010.01.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 12/07/2009] [Accepted: 01/12/2010] [Indexed: 11/29/2022]
Abstract
Human ether à go-go related gene (hERG1) potassium channels underlie the repolarizing I(Kr) current in the heart. Since they are targets of various drugs with cardiac side effects we tested whether the amiodarone derivative 2-methyl-3-(3,5-diiodo-4-carboxymethoxybenzyl)benzofuran (KB130015) blocks hERG1 channels like its parent compound. Using patch-clamp and two-electrode voltage-clamp techniques we found that KB130015 blocks native and recombinant hERG1 channels at high voltages, but it activates them at low voltages. The activating effect has an apparent EC(50) value of 12microM and is brought about by an about 4-fold acceleration of activation kinetics and a shift in voltage-dependent activation by -16mV. Channel activation was not use-dependent and was independent of inactivation gating. KB130015 presumably binds to the hERG1 pore from the cytosolic side and functionally competes with hERG1 block by amiodarone, E4031 (N-[4-[[1-[2-(6-methyl-2-pyridinyl)ethyl]-4-piperidinyl] carbonyl] phenyl] methanesulfonamide dihydrochloride), and sertindole. Vice versa, amiodarone attenuates hERG1 activation by KB130015. Based on synergic channel activation by mallotoxin and KB130015 we conclude that the hERG1 pore contains at least two sites for activators that are functionally coupled among each other and to the cavity-blocker site. KB130015 and amiodarone may serve as lead structures for the identification of hERG1 pore-interacting drugs favoring channel activation vs. block.
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Affiliation(s)
- Guido Gessner
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University of Jena, Germany
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965
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Novel pharmacological approaches for antiarrhythmic therapy. Naunyn Schmiedebergs Arch Pharmacol 2010; 381:187-93. [DOI: 10.1007/s00210-009-0487-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 12/17/2009] [Indexed: 01/14/2023]
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966
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Cantz T, Martin U. Induced pluripotent stem cells: characteristics and perspectives. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2010; 123:107-26. [PMID: 20549467 DOI: 10.1007/10_2010_74] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The induction of pluripotency in somatic cells is widely considered as a major breakthrough in regenerative medicine, because this approach provides the basis for individualized stem cell-based therapies. Moreover, with respect to cell transplantation and tissue engineering, expertise from bioengineering to transplantation medicine is now meeting basic research of stem cell biology.In this chapter, we discuss techniques, potential and possible risks of induced pluripotent stem (iPS) cells in the light of needs for patient-derived pluripotent stem cells. To this end, we compare these cells with other sources of pluripotent cells and discuss the first encouraging results of iPS cells in pharmacological research, disease modeling and cell transplantation, providing fascinating perspectives for future developments in biotechnology and regenerative medicine.
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Affiliation(s)
- Tobias Cantz
- Junior Research Group Stem Cell Biology, Excellence Cluster REBIRTH, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany,
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967
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Di Resta C, Becchetti A. Introduction to ion channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 674:9-21. [PMID: 20549936 DOI: 10.1007/978-1-4419-6066-5_2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ion channels are integral membrane proteins that contain pathways through which ions can flow. By shifting between closed and open conformational states ('gating' process), they control passive ion flow through the plasma membrane. Channels can be gated by membrane potential, or specific ligands, or other agents, such as mechanical stimuli. The efficacy of the gating process and the kinetics of subsequent inactivation or desensitization are regulated by intracellular mechanisms. Many types of membrane channels exist, with different degrees of ion selectivity. By controlling ion fluxes, they typically regulate membrane potential and excitability, shape the action potential, trigger muscle contraction and exocytosis (through Ca2+ influx), regulate cell volume and many other cellular processes. In the first part of the chapter, we give a brief introduction to the main physiological aspects of ion channels, which may not be familiar to molecular biologists. Subsequently, as a reference for later chapters, we summarize the main structural and functional features of the channel-proteins presently known to be related to integrin receptors.
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Affiliation(s)
- Chiara Di Resta
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza, 2.20126 Milano, Italy
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968
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Physical and Functional Interaction between Integrins and hERG1 Channels in Cancer Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 674:55-67. [DOI: 10.1007/978-1-4419-6066-5_6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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969
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Schneider J, Jahnel U, Linz K. Neutral effects of the novel analgesic tapentadol on cardiac repolarization due to mixed ion channel inhibitory activities. Drug Dev Res 2010. [DOI: 10.1002/ddr.20360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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970
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Abstract
The human genome encodes 40 voltage-gated K(+) channels (K(V)), which are involved in diverse physiological processes ranging from repolarization of neuronal and cardiac action potentials, to regulating Ca(2+) signalling and cell volume, to driving cellular proliferation and migration. K(V) channels offer tremendous opportunities for the development of new drugs to treat cancer, autoimmune diseases and metabolic, neurological and cardiovascular disorders. This Review discusses pharmacological strategies for targeting K(V) channels with venom peptides, antibodies and small molecules, and highlights recent progress in the preclinical and clinical development of drugs targeting the K(V)1 subfamily, the K(V)7 subfamily (also known as KCNQ), K(V)10.1 (also known as EAG1 and KCNH1) and K(V)11.1 (also known as HERG and KCNH2) channels.
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971
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Guo D, Klaasse E, de Vries H, Brussee J, Nalos L, Rook MB, Vos MA, van der Heyden MAG, Ijzerman AP. Exploring chemical substructures essential for HERG k(+) channel blockade by synthesis and biological evaluation of dofetilide analogues. ChemMedChem 2009; 4:1722-32. [PMID: 19725081 DOI: 10.1002/cmdc.200900203] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this study we followed a new approach to analyze molecular substructures required for hERG channel blockade. We designed and synthesized 40 analogues of dofetilide (1), a potent hERG potassium channel blocker, and established structure-activity relationships (SAR) for their interaction with this important cardiotoxicity-related off-target. Structural modifications to dofetilide were made by diversifying the substituents on the phenyl rings and the protonated nitrogen and by varying the carbon chain length. The analogues were evaluated in a radioligand binding assay and SAR data were derived with the aim to specify structural features that give rise to hERG toxicity.
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Affiliation(s)
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- Division of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, P.O. Box 9502, 2300 RA Leiden (The Netherlands)
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972
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Marquis RW, Lago AM, Callahan JF, Rahman A, Dong X, Stroup GB, Hoffman S, Gowen M, DelMar EG, Van Wagenen BC, Logan S, Shimizu S, Fox J, Nemeth EF, Roethke T, Smith BR, Ward KW, Bhatnagar P. Antagonists of the calcium receptor. 2. Amino alcohol-based parathyroid hormone secretagogues. J Med Chem 2009; 52:6599-605. [PMID: 19821575 DOI: 10.1021/jm900563e] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
When administered as a single agent to rats, the previously reported calcium receptor antagonist 3 elicited a sustained elevation of plasma PTH resulting in no increase in overall bone mineral density. The lack of a bone building effect for analogue 3 was attributed to the large volume of distribution (V(dss)(rat) = 11 L/kg), producing a protracted plasma PTH profile. Incorporation of a carboxylic acid functionality into the amino alcohol template led to the identification of 12 with a lower volume of distribution (V(dss)(12) = 1.18 L/kg) and a shorter half-life. The zwitterionic nature of antagonist 12 necessitated the utility of an ester prodrug approach to increase overall permeability. Antagonist 12 elicited a rapid and transient increase in circulating levels of PTH following oral dosing of the ester prodrug 11 in the dog. The magnitude and duration of the increases in plasma levels of PTH would be expected to stimulate new bone formation.
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Affiliation(s)
- Robert W Marquis
- Department of Medicinal Chemistry, GlaxoSmithKline, Collegeville, Pennsylvania 19426, USA.
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973
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Raschi E, Ceccarini L, De Ponti F, Recanatini M. hERG-related drug toxicity and models for predicting hERG liability and QT prolongation. Expert Opin Drug Metab Toxicol 2009; 5:1005-21. [PMID: 19572824 DOI: 10.1517/17425250903055070] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND hERG K(+) channels have been recognized as a primary antitarget in safety pharmacology. Their blockade, caused by several drugs with different therapeutic indications, may lead to QT prolongation and, eventually, to potentially fatal arrhythmia, namely torsade de pointes. Therefore, a number of preclinical models have been developed to predict hERG liability early in the drug development process. OBJECTIVE The aim of this review is to outline the present state of the art on drug-induced hERG blockade, providing insights on the predictive value of in vitro and in silico models for hERG liability. METHODS On the basis of latest reports, high-throughput preclinical models have been discussed outlining advantages and limitations. CONCLUSION Although no single model has an absolute value, an integrated risk assessment is recommended to predict the pro-arrhythmic risk of a given drug. This prediction requires expertise from different areas and should encompass emerging issues such as interference with hERG trafficking and QT shortening.
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Affiliation(s)
- Emanuel Raschi
- University of Bologna, Department of Pharmacology, Italy
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974
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Shimizu W, Moss AJ, Wilde AAM, Towbin JA, Ackerman MJ, January CT, Tester DJ, Zareba W, Robinson JL, Qi M, Vincent GM, Kaufman ES, Hofman N, Noda T, Kamakura S, Miyamoto Y, Shah S, Amin V, Goldenberg I, Andrews ML, McNitt S. Genotype-phenotype aspects of type 2 long QT syndrome. J Am Coll Cardiol 2009; 54:2052-62. [PMID: 19926013 DOI: 10.1016/j.jacc.2009.08.028] [Citation(s) in RCA: 174] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2009] [Revised: 08/14/2009] [Accepted: 08/24/2009] [Indexed: 10/20/2022]
Abstract
OBJECTIVES The purpose of this study was to investigate the effect of location, coding type, and topology of KCNH2(hERG) mutations on clinical phenotype in type 2 long QT syndrome (LQTS). BACKGROUND Previous studies were limited by population size in their ability to examine phenotypic effect of location, type, and topology. METHODS Study subjects included 858 type 2 LQTS patients with 162 different KCNH2 mutations in 213 proband-identified families. The Cox proportional-hazards survivorship model was used to evaluate independent contributions of clinical and genetic factors to the first cardiac events. RESULTS For patients with missense mutations, the transmembrane pore (S5-loop-S6) and N-terminus regions were a significantly greater risk than the C-terminus region (hazard ratio [HR]: 2.87 and 1.86, respectively), but the transmembrane nonpore (S1-S4) region was not (HR: 1.19). Additionally, the transmembrane pore region was significantly riskier than the N-terminus or transmembrane nonpore regions (HR: 1.54 and 2.42, respectively). However, for nonmissense mutations, these other regions were no longer riskier than the C-terminus (HR: 1.13, 0.77, and 0.46, respectively). Likewise, subjects with nonmissense mutations were at significantly higher risk than were subjects with missense mutations in the C-terminus region (HR: 2.00), but that was not the case in other regions. This mutation location-type interaction was significant (p = 0.008). A significantly higher risk was found in subjects with mutations located in alpha-helical domains than in subjects with mutations in beta-sheet domains or other locations (HR: 1.74 and 1.33, respectively). Time-dependent beta-blocker use was associated with a significant 63% reduction in the risk of first cardiac events (p < 0.001). CONCLUSIONS The KCNH2 missense mutations located in the transmembrane S5-loop-S6 region are associated with the greatest risk.
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Affiliation(s)
- Wataru Shimizu
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Suita, Osaka, Japan.
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975
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Transfer of rolf S3-S4 linker to HERG eliminates activation gating but spares inactivation. Biophys J 2009; 97:1323-34. [PMID: 19720020 DOI: 10.1016/j.bpj.2009.05.060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 05/20/2009] [Accepted: 05/28/2009] [Indexed: 02/03/2023] Open
Abstract
Studies in Shaker, a voltage-dependent potassium channel, suggest a coupling between activation and inactivation. This coupling is controversial in hERG, a fast-inactivating voltage-dependent potassium channel. To address this question, we transferred to hERG the S3-S4 linker of the voltage-independent channel, rolf, to selectively disrupt the activation process. This chimera shows an intact voltage-dependent inactivation process consistent with a weak coupling, if any, between both processes. Kinetic models suggest that the chimera presents only an open and an inactivated states, with identical transition rates as in hERG. The lower sensitivity of the chimera to BeKm-1, a hERG preferential closed-state inhibitor, also suggests that the chimera presents mainly open and inactivated conformations. This chimera allows determining the mechanism of action of hERG blockers, as exemplified by the test on ketoconazole.
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976
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Roy K, Ghosh G. QSTR with extended topochemical atom (ETA) indices. 13. Modelling of hERG K+channel blocking activity of diverse functional drugs using different chemometric tools. MOLECULAR SIMULATION 2009. [DOI: 10.1080/08927020903015379] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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977
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Chatterjee A, Wang L, Armstrong DL, Rossie S. Activated Rac1 GTPase translocates protein phosphatase 5 to the cell membrane and stimulates phosphatase activity in vitro. J Biol Chem 2009; 285:3872-3882. [PMID: 19948726 DOI: 10.1074/jbc.m109.088427] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Physiological studies of ion channel regulation have implicated the Ser/Thr protein phosphatase 5 (PP5) as an effector of Rac1 GTPase signaling, but direct biochemical evidence for PP5 regulation by Rac1 is lacking. In this study we used immunoprecipitation, in vitro binding, cellular fractionation, and immunofluorescence techniques to show that the tetratricopeptide repeat domain of PP5 interacts specifically and directly with active Rac1. Consequently, activation of Rac1 promoted PP5 translocation to the plasma membrane in intact cells and stimulated PP5 phosphatase activity in vitro. In contrast, neither constitutively active RhoA-V14 nor dominant negative Rac1N17, which preferentially binds GDP and retains an inactive conformation, bound PP5 or stimulated its activity. In addition, Rac1N17 and Rac1(PBRM), a mutant lacking the C-terminal polybasic region required for Rac1 association with the membrane, both failed to cause membrane translocation of PP5. Mutation of predicted contact residues in the PP5 tetratricopeptide repeat domain or within Rac1 also disrupted co-immunoprecipitation of Rac1-PP5 complexes and membrane translocation of PP5. Specific binding of PP5 to activated Rac1 provides a direct mechanism by which PP5 can be stimulated and recruited to participate in Rac1-mediated signaling pathways.
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Affiliation(s)
- Anindya Chatterjee
- From the Department of Biochemistry and Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907 and
| | - Ling Wang
- From the Department of Biochemistry and Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907 and
| | - David L Armstrong
- the Environmental Biology Program, NIEHS, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709
| | - Sandra Rossie
- From the Department of Biochemistry and Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907 and.
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978
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Sanguinetti MC. HERG1 channelopathies. Pflugers Arch 2009; 460:265-76. [PMID: 20544339 DOI: 10.1007/s00424-009-0758-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 11/03/2009] [Accepted: 11/06/2009] [Indexed: 01/08/2023]
Abstract
Human ether a go-go-related gene type 1 (hERG1) K+ channels conduct the rapid delayed rectifier K+ current and mediate action potential repolarization in the heart. Mutations in KCNH2 (the gene that encodes hERG1) causes LQT2, one of the most common forms of long QT syndrome, a disorder of cardiac repolarization that predisposes affected subjects to ventricular arrhythmia and increases the risk of sudden cardiac death. Hundreds of LQT2-associated mutations have been described, and most cause a loss of function by disrupting subunit folding, assembly, or trafficking of the channel to the cell surface. Loss-of-function mutations in hERG1 channels have also recently been implicated in epilepsy. A single gain-of-function mutation has been described that causes short QT syndrome and cardiac arrhythmia. In addition, up-regulation of hERG1 channel expression has been demonstrated in specific tumors and has been associated with skeletal muscle atrophy in mice.
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Affiliation(s)
- Michael C Sanguinetti
- Department of Physiology, Nora Eccles Harrison Cardiovascular Research & Training Institute, University of Utah, 95 South 2000 East, Salt Lake, UT 84112, USA.
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979
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Elliott DJS, Dondas NY, Munsey TS, Sivaprasadarao A. Movement of the S4 segment in the hERG potassium channel during membrane depolarization. Mol Membr Biol 2009; 26:435-47. [DOI: 10.3109/09687680903321081] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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980
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Chatelain FC, Gazzarrini S, Fujiwara Y, Arrigoni C, Domigan C, Ferrara G, Pantoja C, Thiel G, Moroni A, Minor DL. Selection of inhibitor-resistant viral potassium channels identifies a selectivity filter site that affects barium and amantadine block. PLoS One 2009; 4:e7496. [PMID: 19834614 PMCID: PMC2759520 DOI: 10.1371/journal.pone.0007496] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Accepted: 09/23/2009] [Indexed: 12/02/2022] Open
Abstract
Background Understanding the interactions between ion channels and blockers remains an important goal that has implications for delineating the basic mechanisms of ion channel function and for the discovery and development of ion channel directed drugs. Methodology/Principal Findings We used genetic selection methods to probe the interaction of two ion channel blockers, barium and amantadine, with the miniature viral potassium channel Kcv. Selection for Kcv mutants that were resistant to either blocker identified a mutant bearing multiple changes that was resistant to both. Implementation of a PCR shuffling and backcrossing procedure uncovered that the blocker resistance could be attributed to a single change, T63S, at a position that is likely to form the binding site for the inner ion in the selectivity filter (site 4). A combination of electrophysiological and biochemical assays revealed a distinct difference in the ability of the mutant channel to interact with the blockers. Studies of the analogous mutation in the mammalian inward rectifier Kir2.1 show that the T→S mutation affects barium block as well as the stability of the conductive state. Comparison of the effects of similar barium resistant mutations in Kcv and Kir2.1 shows that neighboring amino acids in the Kcv selectivity filter affect blocker binding. Conclusions/Significance The data support the idea that permeant ions have an integral role in stabilizing potassium channel structure, suggest that both barium and amantadine act at a similar site, and demonstrate how genetic selections can be used to map blocker binding sites and reveal mechanistic features.
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Affiliation(s)
- Franck C. Chatelain
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Sabrina Gazzarrini
- Dipartimento di Biologia e Istituto di Biofisica del Consiglio Nazionale delle Ricerche, Università degli Studi di Milano, Milan, Italy
| | - Yuichiro Fujiwara
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Cristina Arrigoni
- Dipartimento di Biologia e Istituto di Biofisica del Consiglio Nazionale delle Ricerche, Università degli Studi di Milano, Milan, Italy
| | - Courtney Domigan
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Giuseppina Ferrara
- Dipartimento di Biologia e Istituto di Biofisica del Consiglio Nazionale delle Ricerche, Università degli Studi di Milano, Milan, Italy
| | - Carlos Pantoja
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
| | - Gerhard Thiel
- Technische Universität Darmstadt, Institute für Botanik, Darmstadt, Germany
| | - Anna Moroni
- Dipartimento di Biologia e Istituto di Biofisica del Consiglio Nazionale delle Ricerche, Università degli Studi di Milano, Milan, Italy
| | - Daniel L. Minor
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
- Department of California Institute for Quantitative Biomedical Research, University of California San Francisco, San Francisco, California, United States of America
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- * E-mail:
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981
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Cui G, Shu W, Wu Q, Chen Y. Effect of Gambogic acid on the regulation of hERG channel in K562 cells in vitro. ACTA ACUST UNITED AC 2009; 29:540-5. [DOI: 10.1007/s11596-009-0503-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Indexed: 02/07/2023]
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982
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Keller DI, Grenier J, Christé G, Dubouloz F, Osswald S, Brink M, Ficker E, Chahine M. Characterization of novel KCNH2 mutations in type 2 long QT syndrome manifesting as seizures. Can J Cardiol 2009; 25:455-62. [PMID: 19668779 DOI: 10.1016/s0828-282x(09)70117-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Long QT syndrome (LQTS) is characterized by corrected QT interval prolongation leading to torsades de pointes and sudden cardiac death. LQTS type 2 (LQTS2) is caused by mutations in the KCNH2 gene, leading to a reduction of the rapidly activating delayed rectifier K+ current and loss of human ether-à-go-go-related gene (hERG) channel function by different mechanisms. Triggers for life-threatening arrhythmias in LQTS2 are often auditory stimuli. OBJECTIVES To screen KCNH2 for mutations in patients with LQTS2 on an electrocardiogram and auditory-induced syncope interpreted as seizures and sudden cardiac death, and to analyze their impact on the channel function in vitro. METHODS The KCNH2 gene was screened for mutations in the index patients of three families. The novel mutations were reproduced in vitro using site-directed mutagenesis and characterized using the Xenopus oocyte expression system in voltage clamp mode. RESULTS Novel KCNH2 mutations (Y493F, A429P and del234-241) were identified in the index patients with mostly typical LQTS2 features on their electrocardiograms. The biochemical data revealed a trafficking defect. The biophysical data revealed a loss of function when mutated hERG channels were coexpressed with the wild type. CONCLUSIONS In all families, at least one patient carrying the mutation had a history of seizures after auditory stimuli, which is a major trigger for arrhythmic events in LQTS2. Seizures are likely due to cardiac syncope as a consequence of mutation-induced loss of function of the rapidly activating delayed rectifier K+ current.
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Affiliation(s)
- Dagmar I Keller
- Cardiology Department, Univesiry Hospital of Basel, Basel, Switzerland
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983
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Gerlach AC, Stoehr SJ, Castle NA. Pharmacological Removal of HumanEther-à-go-go-Related Gene Potassium Channel Inactivation by 3-Nitro-N-(4-phenoxyphenyl) Benzamide (ICA-105574). Mol Pharmacol 2009; 77:58-68. [DOI: 10.1124/mol.109.059543] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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984
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Blass BE, Fensome A, Trybulski E, Magolda R, Gardell SJ, Liu K, Samuel M, Feingold I, Huselton C, Jackson CM, Djandjighian L, Ho D, Hennan J, Janusz JM. Selective Kv1.5 Blockers: Development of (R)-1-(Methylsulfonylamino)-3-[2-(4-methoxyphenyl)ethyl]-4-(4-methoxyphenyl)-2-imidazolidinone (KVI-020/WYE-160020) as a Potential Treatment for Atrial Arrhythmia. J Med Chem 2009; 52:6531-4. [DOI: 10.1021/jm901042m] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Douglas Ho
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts
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985
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Haverinen J, Vornanen M. Responses of Action Potential and K+Currents to Temperature Acclimation in Fish Hearts: Phylogeny or Thermal Preferences? Physiol Biochem Zool 2009; 82:468-82. [DOI: 10.1086/590223] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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986
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Guo J, Massaeli H, Xu J, Jia Z, Wigle JT, Mesaeli N, Zhang S. Extracellular K+ concentration controls cell surface density of IKr in rabbit hearts and of the HERG channel in human cell lines. J Clin Invest 2009; 119:2745-57. [PMID: 19726881 DOI: 10.1172/jci39027] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 06/10/2009] [Indexed: 12/19/2022] Open
Abstract
Although the modulation of ion channel gating by hormones and drugs has been extensively studied, much less is known about how cell surface ion channel expression levels are regulated. Here, we demonstrate that the cell surface density of both the heterologously expressed K+ channel encoded by the human ether-a-go-go-related gene (HERG) and its native counterpart, the rapidly activating delayed rectifier K+ channel (IKr), in rabbit hearts in vivo is precisely controlled by extracellular K+ concentration ([K+]o) within a physiologically relevant range. Reduction of [K+]o led to accelerated internalization and degradation of HERG channels within hours. Confocal analysis revealed colocalization between HERG and ubiquitin during the process of HERG internalization, and overexpression of ubiquitin facilitated HERG degradation under low [K+]o. The HERG channels colocalized with a marker of multivesicular bodies during internalization, and the internalized HERG channels were targeted to lysosomes. Our results provide the first evidence to our knowledge that the cell surface density of a voltage-gated K+ channel, HERG, is regulated by a biological factor, extracellular K+. Because hypokalemia is known to exacerbate long QT syndrome (LQTS) and Torsades de pointes tachyarrhythmias, our findings provide a potential mechanistic link between hypokalemia and LQTS.
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Affiliation(s)
- Jun Guo
- Department of Physiology, Queen's University, Kingston, Ontario, Canada
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987
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Kruse M, Schulze-Bahr E, Corfield V, Beckmann A, Stallmeyer B, Kurtbay G, Ohmert I, Schulze-Bahr E, Brink P, Pongs O. Impaired endocytosis of the ion channel TRPM4 is associated with human progressive familial heart block type I. J Clin Invest 2009; 119:2737-44. [PMID: 19726882 DOI: 10.1172/jci38292] [Citation(s) in RCA: 236] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Accepted: 06/10/2009] [Indexed: 01/20/2023] Open
Abstract
Progressive familial heart block type I (PFHBI) is a progressive cardiac bundle branch disease in the His-Purkinje system that exhibits autosomal-dominant inheritance. In 3 branches of a large South African Afrikaner pedigree with an autosomal-dominant form of PFHBI, we identified the mutation c.19G-->A in the transient receptor potential cation channel, subfamily M, member 4 gene (TRPM4) at chromosomal locus 19q13.3. This mutation predicted the amino acid substitution p.E7K in the TRPM4 amino terminus. TRPM4 encodes a Ca2+-activated nonselective cation (CAN) channel that belongs to the transient receptor potential melastatin ion channel family. Quantitative analysis of TRPM4 mRNA content in human cardiac tissue showed the highest expression level in Purkinje fibers. Cellular expression studies showed that the c.19G-->A missense mutation attenuated deSUMOylation of the TRPM4 channel. The resulting constitutive SUMOylation of the mutant TRPM4 channel impaired endocytosis and led to elevated TRPM4 channel density at the cell surface. Our data therefore revealed a gain-of-function mechanism underlying this type of familial heart block.
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Affiliation(s)
- Martin Kruse
- Institut für Neurale Signalverarbeitung, Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany
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988
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Männikkö R, Overend G, Perrey C, Gavaghan CL, Valentin JP, Morten J, Armstrong M, Pollard CE. Pharmacological and electrophysiological characterization of nine, single nucleotide polymorphisms of the hERG-encoded potassium channel. Br J Pharmacol 2009; 159:102-14. [PMID: 19673885 DOI: 10.1111/j.1476-5381.2009.00334.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Potencies of compounds blocking K(V)11.1 [human ether-ago-go-related gene (hERG)] are commonly assessed using cell lines expressing the Caucasian wild-type (WT) variant. Here we tested whether such potencies would be different for hERG single nucleotide polymorphisms (SNPs). EXPERIMENTAL APPROACH SNPs (R176W, R181Q, Del187-189, P347S, K897T, A915V, P917L, R1047L, A1116V) and a binding-site mutant (Y652A) were expressed in Tet-On CHO-K1 cells. Potencies [mean IC(50); lower/upper 95% confidence limit (CL)] of 48 hERG blockers was estimated by automated electrophysiology [IonWorks HT (IW)]. In phase one, rapid potency comparison of each WT-SNP combination was made for each compound. In phase two, any compound-SNP combinations from phase one where the WT upper/lower CL did not overlap with those of the SNPs were re-examined. Electrophysiological WT and SNP parameters were determined using conventional electrophysiology. KEY RESULTS IW detected the expected sixfold potency decrease for propafenone in Y652A. In phase one, the WT lower/upper CL did not overlap with those of the SNPs for 77 compound-SNP combinations. In phase two, 62/77 cases no longer yielded IC(50) values with non-overlapping CLs. For seven of the remaining 15 cases, there were non-overlapping CLs but in the opposite direction. For the eight compound-SNP combinations with non-overlapping CLs in the same direction as for phase 1, potencies were never more than twofold apart. The only statistically significant electrophysiological difference was the voltage dependence of activation of R1047L. CONCLUSION AND IMPLICATIONS Potencies of hERG channel blockers defined using the Caucasian WT sequence, in this in vitro assay, were representative of potencies for common SNPs.
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989
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Odermarsky M, Lykkesfeldt J, Liuba P. Poor vitamin C status is associated with increased carotid intima-media thickness, decreased microvascular function, and delayed myocardial repolarization in young patients with type 1 diabetes. Am J Clin Nutr 2009; 90:447-52. [PMID: 19553299 DOI: 10.3945/ajcn.2009.27602] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Vascular endothelial dysfunction, accelerated thickening of arterial intima, and changes in ventricular repolarization contribute to increased cardiovascular morbidity in type 1 diabetes (T1D). Although vitamin C has important antioxidant functions and increased oxidative stress is a central mechanism of cardiovascular dysfunction in T1D, the relation between vitamin C and the cardiovascular system in young diabetic patients has not been investigated. OBJECTIVE In a cohort of young patients with T1D, we investigated the relation of plasma concentrations of vitamin C with indexes of vascular function and structure and duration of the QT interval corrected for heart rate (QT(c)). DESIGN Carotid artery intima-media thickness, cutaneous microvascular function, and duration of the QT(c) interval were measured in 59 patients (mean age: 17 y; range: 10-22 y) with T1D (diabetes duration: 3-20 y). Plasma vitamin C was analyzed by HPLC with coulometric detection. RESULTS Carotid artery intima-media thickness and duration of the QT(c) interval were higher in patients in the lowest tertile of vitamin C than in those in the highest tertile (P < 0.05 for both). The cutaneous microvascular response to acetylcholine was lower (P = 0.003) in the lowest tertile group than in the highest tertile group, but the response to sodium nitroprusside was not significantly different between these 2 groups. All differences remained significant after adjustment for age, sex, diabetes duration, body mass index, and glycated hemoglobin. CONCLUSIONS In this relatively small-scale cross-sectional study of young patients with T1D, lower plasma concentrations of vitamin C seem to be associated with adverse changes in the microcirculation, peripheral arteries, and ventricular repolarization. Large-scale prospective studies are needed to confirm these results and to clarify the underlying mechanisms.
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Affiliation(s)
- Michal Odermarsky
- Division of Pediatric Cardiology, Department of Pediatrics, Lund University Hospital, 221 85 Lund, Sweden
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990
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Cubeddu LX. Iatrogenic QT Abnormalities and Fatal Arrhythmias: Mechanisms and Clinical Significance. Curr Cardiol Rev 2009; 5:166-76. [PMID: 20676275 PMCID: PMC2822139 DOI: 10.2174/157340309788970397] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 01/30/2009] [Accepted: 01/31/2009] [Indexed: 11/22/2022] Open
Abstract
Severe and occasionally fatal arrhythmias, commonly presenting as Torsade de Pointes [TdP] have been reported with Class III-antiarrhythmics, but also with non-antiarrhythmic drugs. Most cases result from an action on K(+) channels encoded by the HERG gene responsible for the IKr repolarizing current, leading to a long QT and repolarization abnormalities. The hydrophobic central cavity of the HERG-K+ channels, allows a large number of structurally unrelated drugs to bind and cause direct channel inhibition. Some examples are dofetilide, quinidine, sotalol, erythromycin, grepafloxacin, cisapride, dolasetron, thioridazine, haloperidol, droperidol and pimozide. Other drugs achieve channel inhibition indirectly by impairing channel traffic from the endoplasmic reticulum to the cell membrane, decreasing channel membrane density (pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol). Whereas, ketoconazole, fluoxetine and norfluoxetine induce both direct channel inhibition and impaired channel trafficking. Congenital long QT syndrome, subclinical ion-channel mutations, subjects and relatives of subjects with previous history of drug-induced long QT or TdP, dual drug effects on cardiac repolarization [long QT plus increased QT dispersion], increased transmural dispersion of repolarization and T wave abnormalities, use of high doses, metabolism inhibitors and/or combinations of QT prolonging drugs, hypokalemia, structural cardiac disease, sympathomimetics, bradycardia, women and older age, have been shown to increase the risk for developing drug-induced TdP. Because most of these reactions are preventable, careful evaluation of risk factors and increased knowledge of drugs use associated with repolarization abnormalities is strongly recommended. Future genetic testing and development of practical and simple provocation tests are in route to prevent iatrogenic TdP.
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Affiliation(s)
- Luigi X Cubeddu
- Nova Southeastern University, HPD, Cardiovascular and Metabolic Research Division, Fort Lauderdale, FL, USA
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991
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The role of hERG1 K+ channels and a functional link between hERG1 K+ channels and SDF-1 in acute leukemic cell migration. Exp Cell Res 2009; 315:2256-64. [DOI: 10.1016/j.yexcr.2009.04.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 04/13/2009] [Accepted: 04/21/2009] [Indexed: 11/22/2022]
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992
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Kim MY, Aguilar M, Hodge A, Vigmond E, Shrier A, Glass L. Stochastic and spatial influences on drug-induced bifurcations in cardiac tissue culture. PHYSICAL REVIEW LETTERS 2009; 103:058101. [PMID: 19792536 DOI: 10.1103/physrevlett.103.058101] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2008] [Revised: 05/04/2009] [Indexed: 05/28/2023]
Abstract
The addition of a drug that specifically blocks a potassium channel in spontaneously beating aggregates of chick heart cells leads to complex bifurcations over time. A stochastic partial differential equation model based on discrete ionic currents recorded in these cells demonstrates that drug diffusion and noise can induce the coupled beats and bursting rhythms observed. These results provide further evidence that stochastic events at a subcellular level are needed to understand complex cardiac arrhythmias and play an important role in the onset of these arrhythmias.
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Affiliation(s)
- Min-Young Kim
- Department of Physiology, McGill University, Montreal, Quebec, Canada
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993
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Stringer J, Welsh C, Tommasello A. Methadone-associated Q-T interval prolongation and torsades de pointes. Am J Health Syst Pharm 2009; 66:825-33. [PMID: 19386945 DOI: 10.2146/ajhp070392] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
PURPOSE The association of methadone with Q-T interval prolongation and torsades de pointes (TdP) is reviewed, and recommendations for preventing Q-T interval prolongation in methadone users are provided. SUMMARY Abnormalities in voltage-gated potassium channels have been shown to lead to prolonged action potentials that are expressed as long Q-T intervals, and methadone has been found to interact with the voltage-gated potassium channels of the myocardium. While cardiac arrhythmias in methadone users have been reported for several decades, specific reports of methadone-associated Q-T interval prolongation and TdP did not appear in the literature until the early part of the 21st century. Because not every patient experiences Q-T interval prolongation with methadone, recent research has elucidated risk factors that predispose patients to this adverse effect, including female sex, hypokalemia, high-dose methadone, drug interactions, underlying cardiac conditions, unrecognized congenital long Q-T interval syndrome, and predisposing DNA polymorphisms. Given the high mortality rates seen in untreated illicit opioid users and the clear efficacy of methadone in treating opioid addiction, the risk of using methadone, even in a patient with other risk factors for Q-T interval prolongation, may outweigh the alternative of no pharmacologic treatment. A baseline electrocardiogram (ECG), personal and family history of syncope, and a complete medication history should be obtained before a patient begins treatment with methadone. Given the apparent synergistic effects of parenteral methadone and chlorobutanol, oral methadone should be used whenever possible. CONCLUSION Q-T interval prolongation and TdP associated with the use of methadone are potentially fatal adverse effects. A thorough patient history and ECG monitoring are essential for patients treated with this agent, and alterations in treatment options may be necessary.
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Affiliation(s)
- John Stringer
- Pharmacy, Saint Barnabas Behavioral Health Center, Toms River, NJ 08754, USA.
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994
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Tran DX, Sato D, Yochelis A, Weiss JN, Garfinkel A, Qu Z. Bifurcation and chaos in a model of cardiac early afterdepolarizations. PHYSICAL REVIEW LETTERS 2009; 102:258103. [PMID: 19659123 PMCID: PMC2726623 DOI: 10.1103/physrevlett.102.258103] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Indexed: 05/03/2023]
Abstract
Excitable cells can exhibit complex patterns of oscillations, such as spiking and bursting. In cardiac cells, pathological voltage oscillations, called early afterdepolarizations (EADs), have been widely observed under disease conditions, yet their dynamical mechanisms remain unknown. Here, we show that EADs are caused by Hopf and homoclinic bifurcations. During period pacing, chaos always occurs at the transition from no EAD to EADs as the stimulation frequency decreases, providing a distinct explanation for the irregular EAD behavior frequently observed in experiments.
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Affiliation(s)
- Diana X. Tran
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Molecular, Cellular, and Integrative Physiology Program, University of California, Los Angeles, California 90095, USA
| | - Daisuke Sato
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
| | - Arik Yochelis
- Department of Chemical Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel
| | - James N. Weiss
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
| | - Alan Garfinkel
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Department of Physiological Science, University of California, Los Angeles, California 90095, USA
| | - Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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995
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Zachariae U, Giordanetto F, Leach AG. Side Chain Flexibilities in the Human Ether-a-go-go Related Gene Potassium Channel (hERG) Together with Matched-Pair Binding Studies Suggest a New Binding Mode for Channel Blockers. J Med Chem 2009; 52:4266-76. [DOI: 10.1021/jm900002x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ulrich Zachariae
- Physical and Computational Chemistry, AstraZeneca, Mereside, Alderley Park, Macclesfield SK11 4TG, U.K
| | | | - Andrew G. Leach
- Physical and Computational Chemistry, AstraZeneca, Mereside, Alderley Park, Macclesfield SK11 4TG, U.K
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996
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Grether U, Bénardeau A, Benz J, Binggeli A, Blum D, Hilpert H, Kuhn B, Märki HP, Meyer M, Mohr P, Püntener K, Raab S, Ruf A, Schlatter D. Design and Biological Evaluation of Novel, Balanced Dual PPARα/γ Agonists. ChemMedChem 2009; 4:951-6. [DOI: 10.1002/cmdc.200800425] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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997
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Marquis RW, Lago AM, Callahan JF, Trout REL, Gowen M, DelMar EG, Van Wagenen BC, Logan S, Shimizu S, Fox J, Nemeth EF, Yang Z, Roethke T, Smith BR, Ward KW, Lee J, Keenan RM, Bhatnagar P. Antagonists of the Calcium Receptor I. Amino Alcohol-Based Parathyroid Hormone Secretagogues. J Med Chem 2009; 52:3982-93. [DOI: 10.1021/jm900364m] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Robert W. Marquis
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Amparo M. Lago
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - James F. Callahan
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Robert E. Lee Trout
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Maxine Gowen
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Eric G. DelMar
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Bradford C. Van Wagenen
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Sarah Logan
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Scott Shimizu
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - John Fox
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Edward F. Nemeth
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Zheng Yang
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Theresa Roethke
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Brian R. Smith
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Keith W. Ward
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - John Lee
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Richard M. Keenan
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
| | - Pradip Bhatnagar
- Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, NPS Pharmaceuticals, 550 Hills Drive, Bedminster, New Jersey 07921
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998
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Park SJ, Choi KS, Shin DH, Kim JS, Jang DS, Youm JB, Choe H, Earm YE, Kim SJ. Effects of mixed herbal extracts from parched Puerariae radix, gingered Magnoliae cortex, Glycyrrhizae radix and Euphorbiae radix (KIOM-79) on cardiac ion channels and action potentials. J Korean Med Sci 2009; 24:403-12. [PMID: 19543501 PMCID: PMC2698184 DOI: 10.3346/jkms.2009.24.3.403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 07/25/2008] [Indexed: 11/20/2022] Open
Abstract
KIOM-79, a mixture of ethanol extracts from four herbs (parched Puerariae radix, gingered Magnoliae cortex, Glycyrrhizae radix and Euphorbiae radix), has been developed for the potential therapeutic application to diabetic symptoms. Because screening of unexpected cardiac arrhythmia is compulsory for the new drug development, we investigated the effects of KIOM-79 on the action potential (AP) and various ion channel currents in cardiac myocytes. KIOM-79 decreased the upstroke velocity (V(max)) and plateau potential while slightly increased the duration of action potential (APD). Consistent with the decreased V(max) and plateau potential, the peak amplitude of Na+ current (I(Na)) and Ca2+ current (I(Ca,L)) were decreased by KIOM-79. KIOM-79 showed dual effects on hERG K+ current; increase of depolarization phase current (I(depol)) and decreased tail current at repolarization phase (I(tail)). The increase of APD was suspected due to the decreased I(tail). In computer simulation, the change of cardiac action potential could be well simulated based on the effects of KIOM-79 on various membrane currents. As a whole, the influence of KIOM-79 on cardiac ion channels are minor at concentrations effective for the diabetic models (0.1-10 microg/mL). The results suggest safety in terms of the risk of cardiac arrhythmia. Also, our study demonstrates the usefulness of the cardiac computer simulation in screening drug-induced long-QT syndrome.
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Affiliation(s)
- Su Jung Park
- Department of Physiology, Seoul National University College of Medicine, Seoul, Korea
| | - Kwan Seok Choi
- Department of Physiology, Seoul National University College of Medicine, Seoul, Korea
| | - Dong Hoon Shin
- Department of Physiology, Seoul National University College of Medicine, Seoul, Korea
| | - Jin Sook Kim
- Department of Herbal Pharmaceutical Development, Korea Institute of Oriental Medicine, Daejeon, Korea
| | - Dae Sik Jang
- Department of Herbal Pharmaceutical Development, Korea Institute of Oriental Medicine, Daejeon, Korea
| | - Jae Beom Youm
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology and Biophysics, Cardiovascular and Metabolic Disease Center, Inje University College of Medicine, Busan, Korea
| | - Han Choe
- Department of Physiology and Research Institute for Biomacromolecules, University of Ulsan College of Medicine, Seoul, Korea
| | - Yung E Earm
- Department of Physiology, Seoul National University College of Medicine, Seoul, Korea
| | - Sung Joon Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul, Korea
- Kidney Research Institute (KRI), Seoul National University Medical Research Center, Seoul, Korea
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999
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Hansen K, Rathke F, Schroeter T, Rast G, Fox T, Kriegl JM, Mika S. Bias-Correction of Regression Models: A Case Study on hERG Inhibition. J Chem Inf Model 2009; 49:1486-96. [DOI: 10.1021/ci9000794] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Katja Hansen
- University of Technology, Berlin, Germany, Departments of Drug Discovery Support and Lead Discovery, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach a.d. Riss, Germany, and idalab GmbH, Berlin, Germany
| | - Fabian Rathke
- University of Technology, Berlin, Germany, Departments of Drug Discovery Support and Lead Discovery, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach a.d. Riss, Germany, and idalab GmbH, Berlin, Germany
| | - Timon Schroeter
- University of Technology, Berlin, Germany, Departments of Drug Discovery Support and Lead Discovery, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach a.d. Riss, Germany, and idalab GmbH, Berlin, Germany
| | - Georg Rast
- University of Technology, Berlin, Germany, Departments of Drug Discovery Support and Lead Discovery, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach a.d. Riss, Germany, and idalab GmbH, Berlin, Germany
| | - Thomas Fox
- University of Technology, Berlin, Germany, Departments of Drug Discovery Support and Lead Discovery, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach a.d. Riss, Germany, and idalab GmbH, Berlin, Germany
| | - Jan M. Kriegl
- University of Technology, Berlin, Germany, Departments of Drug Discovery Support and Lead Discovery, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach a.d. Riss, Germany, and idalab GmbH, Berlin, Germany
| | - Sebastian Mika
- University of Technology, Berlin, Germany, Departments of Drug Discovery Support and Lead Discovery, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach a.d. Riss, Germany, and idalab GmbH, Berlin, Germany
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1000
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Gu DF, Li XL, Qi ZP, Shi SS, Hu MQ, Liu DM, She CB, Lv YJ, Li BX, Yang BF. Blockade of HERG K+ channel by isoquinoline alkaloid neferine in the stable transfected HEK293 cells. Naunyn Schmiedebergs Arch Pharmacol 2009; 380:143-51. [PMID: 19424681 DOI: 10.1007/s00210-009-0419-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Accepted: 04/07/2009] [Indexed: 11/24/2022]
Abstract
We studied the effects of isoquinoline alkaloid neferine (Nef) extracted from the seed embryo of Nelumbo nucifera Gaertn on Human ether-à-go-go-related gene (HERG) channels stably expressed in human embryonic kidney (HEK293) cells using whole-cell patch clamp technique, western blot analysis and immunofluorescence experiment. Nef induced a concentration-dependent decrease in current amplitude according to the voltage steps and tail currents of HERG with an IC(50) of 7.419 microM (n(H) -0.5563). Nef shifted the activation curve in a significantly negative direction and accelerated recovery from inactivation and onset of inactivation, however, slowed deactivation. In addition, it had no significant influence on steady-state inactivation curve. Western blot and immunofluorescence results suggested Nef had no significant effect on the expression of HERG protein. In summary, Nef can block HERG K(+) channels that functions by changing the channel activation and inactivation kinetics. Nef has no effect on the generation and trafficking of HERG protein. A blocked-off HERG channel was one mechanism of the anti-arrhythmic effects by Nef.
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Affiliation(s)
- Dong-fang Gu
- Department of Pharmacology, Harbin Medical University, Harbin, People's Republic of China
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