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Arrighi F, Granese A, Chimenti P, Guglielmi P. Novel therapeutic opportunities for Toxoplasma gondii, Trichomonas vaginalis and Giardia intestinalis infections. Expert Opin Ther Pat 2023; 33:211-245. [PMID: 37099697 DOI: 10.1080/13543776.2023.2206017] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
INTRODUCTION Toxoplasma gondii, Trichomonas vaginalis and Giardia intestinalis are the causative agents of Toxoplasmosis, Trichomoniasis and Giardiasis, three important infections threatening human health and affecting millions of people worldwide. Although drugs and treatment are available to fight these protozoan parasites, side-effects and increasing drug resistance, require continuous efforts for the development of novel effective drugs. AREAS COVERED The patents search was carried out in September/October 2022 with four official scientific databases (Espacenet, Scifinder, Reaxys, Google Patents). Treatments for Toxoplasmosis, Trichomoniasis and Giardiasis (2015-2022) have been grouped according to their chemotypes. In particular, novel chemical entities have been reported and investigated for their structure-activity relationship, when accessible. On the other hand, drug repurposing, extensively exploited to obtain novel anti-protozoal treatment, has been in-depth described. Finally, natural metabolites and extracts have also been reported. EXPERT OPINION T. gondii, T. vaginalis and G. intestinalis are protozoan infections usually controlled by immune system in immunocompetent patients; however, they could represent a threatening health for immunocompromised people. The needs of novel effective drugs, endowed with new mechanisms of actions arises from the increasing drug resistance affecting antibiotic as well as antiprotozoal therapies. In this review different therapeutic approaches to treat protozoan infections have been reported.
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Affiliation(s)
- Francesca Arrighi
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, Rome, Italy
| | - Arianna Granese
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, Rome, Italy
| | - Paola Chimenti
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, Rome, Italy
| | - Paolo Guglielmi
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, Rome, Italy
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Lim W, Verbon A, van de Sande W. Identifying novel drugs with new modes of action for neglected tropical fungal skin diseases (fungal skinNTDs) using an Open Source Drug discovery approach. Expert Opin Drug Discov 2022; 17:641-659. [PMID: 35612364 DOI: 10.1080/17460441.2022.2080195] [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: 01/19/2023]
Abstract
INTRODUCTION The three fungal skin neglected tropical diseases (NTD) mycetoma, chromoblastomycosis and sporotrichosis currently lack prioritization and support to establish drug discovery programs in search for novel treatment options. This has made the efforts to identify novel drugs for these skinNTDs fragmented. AREAS COVERED To help escalate the discovery of novel drugs to treat these fungal skinNTDs, the authors have prepared an overview of the compounds with activity against fungal skinNTDs by analyzing data from individual drug discovery studies including those performed on the Medicines for Malaria Venture (MMV) open access boxes. EXPERT OPINION The authors were unable to identify studies in which causative agents of all three skinNTDs were included, indicating that an integrated approach is currently lacking. From the currently available data, the azoles and iodoquinol were the only compounds with activity against causative agents from the three different fungal skinNTDs. Fungal melanin inhibition enhanced the activity of antifungal agents. For mycetoma, the fenarimols, aminothiazoles and benzimidazole carbamates are currently being investigated in the MycetOS initiative. To come to a more integrated approach to identify drugs active against all three fungal skinNTDs, compounds made in the MycetOS initiative could also be explored for chromoblastomycosis and sporotrichosis.
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Affiliation(s)
- Wilson Lim
- Department of Microbiology and Infectious Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Annelies Verbon
- Department of Microbiology and Infectious Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Wendy van de Sande
- Department of Microbiology and Infectious Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Small conductance calcium activated K + channel inhibitor decreases stretch induced vulnerability to atrial fibrillation. IJC HEART & VASCULATURE 2021; 37:100898. [PMID: 34746364 PMCID: PMC8554272 DOI: 10.1016/j.ijcha.2021.100898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/05/2021] [Accepted: 10/16/2021] [Indexed: 12/11/2022]
Abstract
Background Atrial dilation is an important risk factor for atrial fibrillation (AF) and animal studies have found that acute atrial dilation shortens the atrial effective refractory period (AERP) and increases the risk of AF. Stretch activated ion channels (SACs) and calcium channels play a role in this. The expression profile and calcium dependent activation makes the small conductance calcium activated K+ channel (KCa2.x) a candidate for coupling stretch induced increases in intracellular calcium through K+-efflux and thereby shortening of atrial refractoriness. Objectives We hypothesized that KCa2.x channel inhibitors can prevent the stretch induced shortening of AERP and protect the heart from AF. Methods The effect of KCa2 channel inhibitor (N-(pyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (ICA) 1 µM) was investigated using the isolated perfused rabbit heart preparation. To stretch the left atrium (LA) a balloon was inserted and inflated. AERP and action potential duration (APD) were recorded before and after atrial stretch. AF was induced by burst pacing the LA at different degrees of atrial stretch. Results Stretching of the LA by increasing the balloon pressure from 0 to 20 mmHg shortened the AERP by 8.6 ± 1 ms. In comparison, the KCa2 inhibitor ICA significantly attenuated the stretch induced shortening of AERP to 2.5 ± 1.1 ms. Total AF duration increased linearly with atrial balloon pressure. This relationship was not found in the presence of ICA. ICA lowered the incidence of AF induction and total AF duration. Conclusion The KCa2 channel inhibitor ICA attenuates the acute stretch induced shortening of AERP and decreases stretch induced vulnerability to AF.
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Targeting of Potassium Channels in Cardiac Arrhythmias. Trends Pharmacol Sci 2021; 42:491-506. [PMID: 33858691 DOI: 10.1016/j.tips.2021.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 03/14/2021] [Accepted: 03/17/2021] [Indexed: 02/07/2023]
Abstract
Cardiomyocytes are endowed with a complex repertoire of ion channels, responsible for the generation of action potentials (APs), travelling waves of electrical excitation, propagating throughout the heart and leading to cardiac contractions. Cardiac AP waveforms are shaped by a striking diversity of K+ channels. The pivotal role of K+ channels in cardiac health and disease is underscored by the dramatic impact that K+ channel dysfunction has on cardiac arrhythmias. The development of drugs targeted to specific K+ channels is expected to provide an optimized approach to antiarrhythmic therapy. Here, we review the functional roles of cardiac potassium channels under normal and diseased states. We survey current antiarrhythmic drugs (AADs) targeted to voltage-gated and Ca2+-activated K+ channels and highlight future research opportunities.
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Zhang XD, Thai PN, Lieu DK, Chiamvimonvat N. Cardiac small-conductance calcium-activated potassium channels in health and disease. Pflugers Arch 2021; 473:477-489. [PMID: 33624131 PMCID: PMC7940285 DOI: 10.1007/s00424-021-02535-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 12/22/2022]
Abstract
Small-conductance Ca2+-activated K+ (SK, KCa2) channels are encoded by KCNN genes, including KCNN1, 2, and 3. The channels play critical roles in the regulation of cardiac excitability and are gated solely by beat-to-beat changes in intracellular Ca2+. The family of SK channels consists of three members with differential sensitivity to apamin. All three isoforms are expressed in human hearts. Studies over the past two decades have provided evidence to substantiate the pivotal roles of SK channels, not only in healthy heart but also with diseases including atrial fibrillation (AF), ventricular arrhythmia, and heart failure (HF). SK channels are prominently expressed in atrial myocytes and pacemaking cells, compared to ventricular cells. However, the channels are significantly upregulated in ventricular myocytes in HF and pulmonary veins in AF models. Interests in cardiac SK channels are further fueled by recent studies suggesting the possible roles of SK channels in human AF. Therefore, SK channel may represent a novel therapeutic target for atrial arrhythmias. Furthermore, SK channel function is significantly altered by human calmodulin (CaM) mutations, linked to life-threatening arrhythmia syndromes. The current review will summarize recent progress in our understanding of cardiac SK channels and the roles of SK channels in the heart in health and disease.
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Affiliation(s)
- Xiao-Dong Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, One Shields Avenue, GBSF 6315, Davis, CA, 95616, USA.
- Department of Veterans Affairs, Northern California Health Care System, 10535 Hospital Way, Mather, CA, 95655, USA.
| | - Phung N Thai
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, One Shields Avenue, GBSF 6315, Davis, CA, 95616, USA
- Department of Veterans Affairs, Northern California Health Care System, 10535 Hospital Way, Mather, CA, 95655, USA
| | - Deborah K Lieu
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, One Shields Avenue, GBSF 6315, Davis, CA, 95616, USA
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, One Shields Avenue, GBSF 6315, Davis, CA, 95616, USA.
- Department of Veterans Affairs, Northern California Health Care System, 10535 Hospital Way, Mather, CA, 95655, USA.
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, 95616, USA.
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Husain AA, Bisht KS. Thiocyanation and 2-Amino-1,3-thiazole Formation in Water Using Recoverable and Reusable Glycosylated Resorcin[4]arene Cavitands. J Org Chem 2020; 85:9928-9935. [PMID: 32674572 DOI: 10.1021/acs.joc.0c01150] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A family of three spatially directional resorcin[4]arene cavitand glycoconjugates (RCGs) have been applied as efficient recoverable and reusable inverse phase transfer catalysts for eco- and environmentally friendly thiocyanation and 2-amino-1,3-thiazole formation reactions in water. The results show that RCGs (1 mol %) were capable of hosting and catalyzing various water-insoluble bromo/thiocyanato substrates in water without the use of any co-organic solvents. The recoverability and reusability of RCG catalytic systems, that is, RCG1 and RCG3, were also examined upon a simple extraction of the desired products using DCM or ethyl acetate, followed by subjecting the recovered aqueous solution containing the RCG catalysts to the next reaction cycles.
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Affiliation(s)
- Ali A Husain
- Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, CHE 202, Tampa, Fl 33620, United States
| | - Kirpal S Bisht
- Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, CHE 202, Tampa, Fl 33620, United States
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Saljic A, Soattin L, Trachsel DS, Boddum K, Jespersen T. In vivo knockdown of SK3 channels using antisense oligonucleotides protects against atrial fibrillation in rats. J Mol Cell Cardiol 2020; 147:18-26. [PMID: 32768409 DOI: 10.1016/j.yjmcc.2020.07.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 07/06/2020] [Accepted: 07/28/2020] [Indexed: 02/02/2023]
Abstract
INTRODUCTION GapmeRs are oligonucleotides that bind to a specific RNA sequence and thereby affecting posttranscriptional gene regulation. They therefore hold the potential to manipulate targets where current pharmacological modulators are inefficient or exhibit adverse side effects. Here, we show that a treatment with a GapmeR, mediating knockdown of small conductance Ca2+-activated K+ channels (SK3), has an in vivo protective effect against atrial fibrillation (AF) in rats. MATERIAL AND METHODS A unique SK3-GapmeR design was selected after thorough in vitro evaluation. 22 rats were randomly assigned to receive either 50 mg/kg SK3-GapmeR or vehicle subcutaneously once a week for two weeks. Langendorff experiments were performed seven days after the last injection, where action potential duration (APD90), effective refractory period (ERP) and AF propensity were investigated. SK3 channel activity was evaluated using the SK channel blocker, ICA (N-(pyridin-2-yl)-4-(pyridine-2-yl)thiazol-2-amine). SK3 protein expression was assessed by Western Blot. RESULTS The designed GapmeR effectively down-regulate the SK3 protein expression in the heart (48% downregulation, p = 0.0095) and did indeed protect against AF. Duration of AF episodes elicited by burst pacing in the rats treated with SK3-GapmeR was reduced 78% compared to controls (3.7 s vs. 16.8 s, p = 0.0353). The number of spontaneous AF episodes were decreased by 68% in the SK3-GapmeR group (39 episodes versus 123 in the control group, respectively) and were also significantly shorter in duration (7.2 s versus 29.7 s in the control group, p = 0.0327). Refractoriness was not altered at sinus rhythm, but ERP prolongation following ICA application was blunted in the SK3-GapmeR group. CONCLUSION The selected GapmeR silenced the cardiac SK3 channels, thereby preventing AF in rats. Thus, GapmeR technology can be applied as an experimental tool of downregulation of cardiac proteins and could potentially offer a novel modality for treatment of cardiac diseases.
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Affiliation(s)
- Arnela Saljic
- Laboratory of Cardiac Physiology, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark
| | - Luca Soattin
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom; Laboratory of Cardiac Physiology, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark
| | - Dagmar S Trachsel
- Laboratory of Cardiac Physiology, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark
| | - Kim Boddum
- Laboratory of Cardiac Physiology, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark
| | - Thomas Jespersen
- Laboratory of Cardiac Physiology, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark.
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Brown BM, Shim H, Christophersen P, Wulff H. Pharmacology of Small- and Intermediate-Conductance Calcium-Activated Potassium Channels. Annu Rev Pharmacol Toxicol 2019; 60:219-240. [PMID: 31337271 DOI: 10.1146/annurev-pharmtox-010919-023420] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The three small-conductance calcium-activated potassium (KCa2) channels and the related intermediate-conductance KCa3.1 channel are voltage-independent K+ channels that mediate calcium-induced membrane hyperpolarization. When intracellular calcium increases in the channel vicinity, it calcifies the flexible N lobe of the channel-bound calmodulin, which then swings over to the S4-S5 linker and opens the channel. KCa2 and KCa3.1 channels are highly druggable and offer multiple binding sites for venom peptides and small-molecule blockers as well as for positive- and negative-gating modulators. In this review, we briefly summarize the physiological role of KCa channels and then discuss the pharmacophores and the mechanism of action of the most commonly used peptidic and small-molecule KCa2 and KCa3.1 modulators. Finally, we describe the progress that has been made in advancing KCa3.1 blockers and KCa2.2 negative- and positive-gating modulators toward the clinic for neurological and cardiovascular diseases and discuss the remaining challenges.
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Affiliation(s)
- Brandon M Brown
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | - Heesung Shim
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | | | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA;
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Simó-Vicens R, Bomholtz SH, Sørensen US, Bentzen BH. 2,6-Bis(2-Benzimidazolyl)Pyridine (BBP) Is a Potent and Selective Inhibitor of Small Conductance Calcium-Activated Potassium (SK) Channels. Front Pharmacol 2018; 9:1409. [PMID: 30559671 PMCID: PMC6287599 DOI: 10.3389/fphar.2018.01409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/16/2018] [Indexed: 11/13/2022] Open
Abstract
A variety of polycyclic pyridines have been proposed as inhibitors of the small conductance calcium-activated potassium (SK) channel. To this group belongs 2,6-bis(2-benzimidazolyl)pyridine (BBP), a commercially and readily available small organic compound which has earlier been described in a broad range of chemical and biological uses. Here, we show how BBP can also be used as a potent and specific SK channel blocker in vitro. The potency of BBP was measured using automatic patch clamp on all three SK channel subtypes, resulting in similar IC50 of 0.4 μM. We also assessed the selectivity of BBP on a panel of calcium-activated and voltage-activated potassium channels using two-electrode voltage clamp, automatic and manual patch clamp. BBP did not have any effect on IK, Kir2.1, Kir3.1+Kir3.4, Kv1.5, Kv4.3/KCHIP2 and Kv7.1/KCNE1 currents and was 4.8-fold and 46-fold more potent on all SK channel subtypes vs. BK and hERG channels, respectively. Moreover, we were able to identify H491 as a critical amino acid for the pharmacological effect of BBP on the SK channel. From a medicinal chemistry perspective, BBP could be used as a starting point for the design of new and improved SK inhibitors.
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Affiliation(s)
- Rafel Simó-Vicens
- Cardiovascular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Acesion Pharma, Copenhagen, Denmark
| | - Sofia H Bomholtz
- Cardiovascular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Acesion Pharma, Copenhagen, Denmark
| | | | - Bo H Bentzen
- Cardiovascular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Acesion Pharma, Copenhagen, Denmark
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Machado D, Azzali E, Couto I, Costantino G, Pieroni M, Viveiros M. Adjuvant therapies against tuberculosis: discovery of a 2-aminothiazole targeting Mycobacterium tuberculosis energetics. Future Microbiol 2018; 13:1383-1402. [PMID: 30259757 DOI: 10.2217/fmb-2018-0110] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
AIM To evaluate the activity of the 2-aminothiazole UPAR-174 following an unexplored approach: targeting Mycobacterium tuberculosis with lipophilic compounds that present antituberculosis and efflux inhibitory activity. METHODS Antituberculosis activity was assessed against replicating, nonreplicating and intracellular bacilli. Its capacity to inhibit active efflux was determined. ATP quantification and membrane potential analysis were performed. Intracellular activity was studied on human-monocyte-derived macrophages. RESULTS UPAR-174 is an efflux inhibitor active against replicating, nonreplicating and intracellular M. tuberculosis. It dissipates the membrane potential and causes ATP depletion. CONCLUSION Targeting M. tuberculosis with lipophilic efflux inhibitors, exploring their dual activity - dissipation of the proton motive force and efflux inhibition - represents an attractive strategy to fight against drug-resistant tuberculosis.
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Affiliation(s)
- Diana Machado
- Global Health & Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisboa, Portugal
| | - Elisa Azzali
- P4T group, Department of Food & Drug, University of Parma, Parco Area delle Scienze 27/A, Parma, Italy.,Aptuit (Verona) Srl, an Evotec Company, Via Alessandro Fleming, 4, 37135 Verona, Italy
| | - Isabel Couto
- Global Health & Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisboa, Portugal
| | - Gabriele Costantino
- P4T group, Department of Food & Drug, University of Parma, Parco Area delle Scienze 27/A, Parma, Italy
| | - Marco Pieroni
- P4T group, Department of Food & Drug, University of Parma, Parco Area delle Scienze 27/A, Parma, Italy
| | - Miguel Viveiros
- Global Health & Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisboa, Portugal
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Skarsfeldt MA, Bomholtz SH, Lundegaard PR, Lopez-Izquierdo A, Tristani-Firouzi M, Bentzen BH. Atrium-specific ion channels in the zebrafish-A role of I KACh in atrial repolarization. Acta Physiol (Oxf) 2018; 223:e13049. [PMID: 29412518 DOI: 10.1111/apha.13049] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 01/26/2018] [Accepted: 01/29/2018] [Indexed: 12/16/2022]
Abstract
AIM The zebrafish has emerged as a novel model for investigating cardiac physiology and pathology. The aim of this study was to investigate the atrium-specific ion channels responsible for shaping the atrial cardiac action potential in zebrafish. METHODS Using quantitative polymerase chain reaction, we assessed the expression level of atrium-specific potassium channels. The functional role of these channels was studied by patch clamp experiments on isolated atrial and ventricular cardiomyocytes and by optical mapping of explanted adult zebrafish hearts. Finally, surface ECGs were recorded to establish possible in vivo roles of atrial ion channels. RESULTS In isolated adult zebrafish hearts, we identified the expression of kcnk3, kcnk9, kcnn1, kcnn2, kcnn3, kcnj3 and kcnj5, the genes that encode the atrium-specific K2P , KCa 2.x and Kir 3.1/4 (KACh ) ion channels. The electrophysiological data indicate that the acetylcholine-activated inward-rectifying current, IKACh, plays a major role in the zebrafish atrium, whereas K2P 3.1/9.1 and KCa 2.x channels do not appear to be involved in regulating the action potential in the zebrafish heart. CONCLUSION We demonstrate that the acetylcholine-activated inward-rectifying current (IKACh ) current plays a major role in the zebrafish atrium and that the zebrafish could potentially be a cost-effective and reliable model for pharmacological testing of atrium-specific IKACh modulating compounds.
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Affiliation(s)
- M. A. Skarsfeldt
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
- Nora Eccles Harrison Cardiovascular Research and Training Institute; University of Utah; Salt Lake City UT USA
| | - S. H. Bomholtz
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - P. R. Lundegaard
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - A. Lopez-Izquierdo
- Nora Eccles Harrison Cardiovascular Research and Training Institute; University of Utah; Salt Lake City UT USA
| | - M. Tristani-Firouzi
- Nora Eccles Harrison Cardiovascular Research and Training Institute; University of Utah; Salt Lake City UT USA
| | - B. H. Bentzen
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
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Honrath B, Krabbendam IE, Culmsee C, Dolga AM. Small conductance Ca 2+-activated K + channels in the plasma membrane, mitochondria and the ER: Pharmacology and implications in neuronal diseases. Neurochem Int 2017; 109:13-23. [PMID: 28511953 DOI: 10.1016/j.neuint.2017.05.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/24/2017] [Accepted: 05/08/2017] [Indexed: 12/14/2022]
Abstract
Ca2+-activated K+ (KCa) channels regulate after-hyperpolarization in many types of neurons in the central and peripheral nervous system. Small conductance Ca2+-activated K+ (KCa2/SK) channels, a subfamily of KCa channels, are widely expressed in the nervous system, and in the cardiovascular system. Voltage-independent SK channels are activated by alterations in intracellular Ca2+ ([Ca2+]i) which facilitates the opening of these channels through binding of Ca2+ to calmodulin that is constitutively bound to the SK2 C-terminus. In neurons, SK channels regulate synaptic plasticity and [Ca2+]i homeostasis, and a number of recent studies elaborated on the emerging neuroprotective potential of SK channel activation in conditions of excitotoxicity and cerebral ischemia, as well as endoplasmic reticulum (ER) stress and oxidative cell death. Recently, SK channels were discovered in the inner mitochondrial membrane and in the membrane of the endoplasmic reticulum which sheds new light on the underlying molecular mechanisms and pathways involved in SK channel-mediated protective effects. In this review, we will discuss the protective properties of pharmacological SK channel modulation with particular emphasis on intracellularly located SK channels as potential therapeutic targets in paradigms of neuronal dysfunction.
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Affiliation(s)
- Birgit Honrath
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Inge E Krabbendam
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany
| | - Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
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Pharmacological blockade of small conductance Ca 2+-activated K + channels by ICA reduces arrhythmic load in rats with acute myocardial infarction. Pflugers Arch 2017; 469:739-750. [PMID: 28285409 DOI: 10.1007/s00424-017-1962-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/07/2017] [Accepted: 02/20/2017] [Indexed: 01/02/2023]
Abstract
Acute myocardial infarction (AMI) with development of ventricular fibrillation (VF) is a common cause of sudden cardiac death (SCD). At present, no pharmacological treatment has successfully been able to prevent VF in the acute stage of AMI. This study investigates the antiarrhythmic effect of inhibiting small conductance Ca2+-activated K+ (SK) channels using the pore blocker N-(pyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (ICA) in AMI rats. Acute coronary ligation was performed in 26 anesthetized rats, and ECG, monophasic action potentials (MAPs), and ventricular effective refractory period (vERP) were recorded. Rats were randomized into four groups: (i) 3 mg/kg i.v. ICA with AMI (AMI-ICA-group, n = 9), (ii) vehicle with AMI (AMI-vehicle-group, n = 9), (iii) vehicle with sham operation (sham-vehicle-group, n = 8), and (iv) 3 mg/kg i.v. ICA with sham operation (sham-ICA-group, n = 6). At the end of experiments, hearts were stained for the non-perfused area at risk (AAR). AMI resulted in the development of ventricular tachycardia (VT) in all AMI-vehicle and AMI-ICA rats; however, ICA significantly decreased VT duration. VF occurred in 44% of AMI-vehicle rats but not in AMI-ICA rats. Monophasic action potential duration at 80% repolarization (MAPD80) in the ischemic area decreased rapidly in both AMI-vehicle and AMI-ICA rats. However, 5 min after occlusion, MAPD80 returned to baseline in AMI-ICA rats but not in AMI-vehicle rats. The vERP was prolonged in the AMI-ICA group compared to AMI-vehicle after ligation. AAR was similar between the AMI-vehicle group and the AMI-ICA group. In rats with AMI, ICA reduces the burden of arrhythmia.
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Chiamvimonvat N, Chen-Izu Y, Clancy CE, Deschenes I, Dobrev D, Heijman J, Izu L, Qu Z, Ripplinger CM, Vandenberg JI, Weiss JN, Koren G, Banyasz T, Grandi E, Sanguinetti MC, Bers DM, Nerbonne JM. Potassium currents in the heart: functional roles in repolarization, arrhythmia and therapeutics. J Physiol 2017; 595:2229-2252. [PMID: 27808412 DOI: 10.1113/jp272883] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/11/2016] [Indexed: 12/19/2022] Open
Abstract
This is the second of the two White Papers from the fourth UC Davis Cardiovascular Symposium Systems Approach to Understanding Cardiac Excitation-Contraction Coupling and Arrhythmias (3-4 March 2016), a biennial event that brings together leading experts in different fields of cardiovascular research. The theme of the 2016 symposium was 'K+ channels and regulation', and the objectives of the conference were severalfold: (1) to identify current knowledge gaps; (2) to understand what may go wrong in the diseased heart and why; (3) to identify possible novel therapeutic targets; and (4) to further the development of systems biology approaches to decipher the molecular mechanisms and treatment of cardiac arrhythmias. The sessions of the Symposium focusing on the functional roles of the cardiac K+ channel in health and disease, as well as K+ channels as therapeutic targets, were contributed by Ye Chen-Izu, Gideon Koren, James Weiss, David Paterson, David Christini, Dobromir Dobrev, Jordi Heijman, Thomas O'Hara, Crystal Ripplinger, Zhilin Qu, Jamie Vandenberg, Colleen Clancy, Isabelle Deschenes, Leighton Izu, Tamas Banyasz, Andras Varro, Heike Wulff, Eleonora Grandi, Michael Sanguinetti, Donald Bers, Jeanne Nerbonne and Nipavan Chiamvimonvat as speakers and panel discussants. This article summarizes state-of-the-art knowledge and controversies on the functional roles of cardiac K+ channels in normal and diseased heart. We endeavour to integrate current knowledge at multiple scales, from the single cell to the whole organ levels, and from both experimental and computational studies.
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Affiliation(s)
- Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, 95655, USA
| | - Ye Chen-Izu
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA.,Department of Biomedical Engineering, University of California, Davis, Genome and Biomedical Science Facility, Rm 2303, Davis, CA, 95616, USA
| | - Colleen E Clancy
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Isabelle Deschenes
- Department of Physiology and Biophysics, and Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44109, USA.,Heart and Vascular Research Center, MetroHealth Medical Center, Cleveland, OH, 44109, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstrasse 55, 45122, Essen, Germany
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Leighton Izu
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Zhilin Qu
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia
| | - James N Weiss
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Gideon Koren
- Cardiovascular Research Center, Rhode Island Hospital and the Cardiovascular Institute, The Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA
| | - Tamas Banyasz
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Michael C Sanguinetti
- Department of Internal Medicine, University of Utah, Nora Eccles Harrison Cardiovascular Research & Training Institute, Salt Lake City, UT, 84112, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jeanne M Nerbonne
- Departments of Developmental Biology and Internal Medicine, Cardiovascular Division, Washington University Medical School, St Louis, MO, 63110, USA
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Abstract
Despite the epidemiological scale of atrial fibrillation, current treatment strategies are of limited efficacy and safety. Ideally, novel drugs should specifically correct the pathophysiological mechanisms responsible for atrial fibrillation with no other cardiac or extracardiac actions. Atrial-selective drugs are directed toward cellular targets with sufficiently different characteristics in atria and ventricles to modify only atrial function. Several potassium (K+) channels with either predominant expression in atria or distinct electrophysiological properties in atria and ventricles can serve as atrial-selective drug targets. These channels include the ultra-rapidly activating, delayed outward-rectifying Kv1.5 channel conducting IKur, the acetylcholine-activated inward-rectifying Kir3.1/Kir3.4 channel conducting IK,ACh, the Ca2+-activated K+ channels of small conductance (SK) conducting ISK, and the two pore domain K+ (K2P) channels TWIK-1, TASK-1 and TASK-3 that are responsible for voltage-independent background currents ITWIK-1, ITASK-1, and ITASK-3. Here, we briefly review the characteristics of these K+ channels and their roles in atrial fibrillation. The antiarrhythmic potential of drugs targeting the described channels is discussed as well as their putative value in treatment of atrial fibrillation.
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Affiliation(s)
- Ursula Ravens
- Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany; Department of Cardiology and Angiology I, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany; Department of Physiology, Medical Faculty Carl-Gustav-Carus, TU Dresden, Dresden, Germany.
| | - Katja E Odening
- Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany; Department of Cardiology and Angiology I, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany
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Antiarrhythmic effect of the Ca 2+-activated K + (SK) channel inhibitor ICA combined with either amiodarone or dofetilide in an isolated heart model of atrial fibrillation. Pflugers Arch 2016; 468:1853-1863. [PMID: 27722784 PMCID: PMC6763419 DOI: 10.1007/s00424-016-1883-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 08/13/2016] [Accepted: 08/27/2016] [Indexed: 12/22/2022]
Abstract
Dose is an important parameter in terms of both efficacy and adverse effects in pharmacological treatment of atrial fibrillation (AF). Both of the class III antiarrhythmics dofetilide and amiodarone have documented anti-AF effects. While dofetilide has dose-related ventricular side effects, amiodarone primarily has adverse non-cardiac effects. Pharmacological inhibition of small conductance Ca2+-activated K+ (SK) channels has recently been reported to be antiarrhythmic in a number of animal AF models. In a Langendorff model of acutely induced AF on guinea pig hearts, it was investigated whether a combination of the SK channel blocker N-(pyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (ICA) together with either dofetilide or amiodarone provided a synergistic effect. The duration of AF was reduced with otherwise subefficacious concentrations of either dofetilide or amiodarone when combined with ICA, also at a subefficacious concentration. At a concentration level effective as monotherapy, dofetilide produced a marked increase in the QT interval. This QT prolonging effect was absent when combined with ICA at non-efficacious monotherapy concentrations. The results thereby reveal that combination of subefficacious concentrations of an SK channel blocker and either dofetilide or amiodarone can maintain anti-AF properties, while the risk of ventricular arrhythmias is reduced.
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Arora P, Narang R, Nayak SK, Singh SK, Judge V. 2,4-Disubstituted thiazoles as multitargated bioactive molecules. Med Chem Res 2016. [DOI: 10.1007/s00044-016-1610-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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18
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Abstract
INTRODUCTION SK channels have functional importance in the cardiac atrium of many species, including humans. Pharmacological blockage of SK channels has been reported to be antiarrhythmic in animal models of atrial fibrillation; however, the exact antiarrhythmic mechanism of SK channel inhibition remains unclear. OBJECTIVES We speculated that together with a direct inhibition of repolarizing SK current, the previously observed depolarization of the atrial resting membrane potential (RMP) after SK channel inhibition reduces sodium channel availability, thereby prolonging the effective refractory period and slowing the conduction velocity (CV). We therefore aimed at elucidating these properties of SK channel inhibition and the underlying antiarrhythmic mechanisms using microelectrode action potential (AP) recordings and CV measurements in isolated rat atrium. Automated patch clamping and two-electrode voltage clamp were used to access INa and IK,ACh, respectively. RESULTS The SK channel inhibitor N-(pyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (ICA) exhibited antiarrhythmic effects. ICA prevented electrically induced runs of atrial fibrillation in the isolated right atrium and induced atrial postrepolarization refractoriness and depolarized RMP. Moreover, ICA (1-10 μM) was found to slow CV; however, because of a marked prolongation of effective refractory period, the calculated wavelength was increased. Furthermore, at increased pacing frequencies, SK channel inhibition by ICA (10-30 μM) demonstrated prominent depression of other sodium channel-dependent parameters. ICA did not inhibit IK,ACh, but at concentrations above 10 μM, ICA use dependently inhibited INa. CONCLUSIONS SK channel inhibition modulates multiple parameters of AP. It prolongs the AP duration and shifts the RMP towards more depolarized potentials through direct ISK block. This indirectly leads to sodium channel inhibition through accumulation of state dependently inactivated channels, which ultimately slows conduction and decreases excitability. However, a contribution from a direct sodium channel inhibition cannot be ruled. We here propose that the primary antiarrhythmic mechanism of SK channel inhibition is through direct potassium channel block and through indirect sodium channel inhibition.
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Tang X, Zhu Z, Qi C, Wu W, Jiang H. Copper-Catalyzed Coupling of Oxime Acetates with Isothiocyanates: A Strategy for 2-Aminothiazoles. Org Lett 2016; 18:180-3. [PMID: 26729578 DOI: 10.1021/acs.orglett.5b03188] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A new strategy for 2-aminothiazoles is developed via the copper-catalyzed coupling of oxime acetates with isothiocyanates. Various 4-substituted and 4,5-disubstituted 2-aminothiazoles were formed smoothly under mild reaction conditions. This process involved copper-catalyzed N-O bond cleavage, activation of vinyl sp(2) C-H bonds, and C-S/C-N bond formations. It is noteworthy that the oxime acetates were used not only as a substrate but also as a single oxidant.
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Affiliation(s)
- Xiaodong Tang
- School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, P. R. China
| | - Zhongzhi Zhu
- School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, P. R. China
| | - Chaorong Qi
- School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, P. R. China
| | - Wanqing Wu
- School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, P. R. China
| | - Huanfeng Jiang
- School of Chemistry and Chemical Engineering, South China University of Technology , Guangzhou 510640, P. R. China
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20
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van der Heyden MA, Jespersen T. Pharmacological exploration of the resting membrane potential reserve: Impact on atrial fibrillation. Eur J Pharmacol 2016; 771:56-64. [DOI: 10.1016/j.ejphar.2015.11.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 11/06/2015] [Accepted: 11/16/2015] [Indexed: 12/24/2022]
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21
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Antiarrhythmic Effect of Either Negative Modulation or Blockade of Small Conductance Ca2+-activated K+ Channels on Ventricular Fibrillation in Guinea Pig Langendorff-perfused Heart. J Cardiovasc Pharmacol 2015; 66:294-9. [DOI: 10.1097/fjc.0000000000000278] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Zhang XD, Lieu DK, Chiamvimonvat N. Small-conductance Ca2+ -activated K+ channels and cardiac arrhythmias. Heart Rhythm 2015; 12:1845-51. [PMID: 25956967 PMCID: PMC4662728 DOI: 10.1016/j.hrthm.2015.04.046] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Indexed: 01/04/2023]
Abstract
Small-conductance Ca2+ -activated K+ (SK, KCa2) channels are unique in that they are gated solely by changes in intracellular Ca2+ and, hence, function to integrate intracellular Ca2+ and membrane potentials on a beat-to-beat basis. Recent studies have provided evidence for the existence and functional significance of SK channels in the heart. Indeed, our knowledge of cardiac SK channels has been greatly expanded over the past decade. Interests in cardiac SK channels are further driven by recent studies suggesting the critical roles of SK channels in human atrial fibrillation, the SK channel as a possible novel therapeutic target in atrial arrhythmias, and upregulation of SK channels in heart failure in animal models and in human heart failure. However, there remain critical gaps in our knowledge. Specifically, blockade of SK channels in cardiac arrhythmias has been shown to be both antiarrhythmic and proarrhythmic. This contemporary review provides an overview of the literature on the role of cardiac SK channels in cardiac arrhythmias and serves as a discussion platform for the current clinical perspectives. At the translational level, development of SK channel blockers as a new therapeutic strategy in the treatment of atrial fibrillation and the possible proarrhythmic effects merit further considerations and investigations.
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Affiliation(s)
- Xiao-Dong Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, California.
| | - Deborah K Lieu
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, California
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, California; Department of Veterans Affairs, Northern California Health Care System, Mather, California.
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23
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Zhao J, Xu J, Chen J, He M, Wang X. Potassium iodide and ammonium nitrate catalyzed aerobic oxidative cyclization of ketones with thioureas in ionic liquid: an access to 2-aminothiazoles. Tetrahedron 2015. [DOI: 10.1016/j.tet.2014.12.044] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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24
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Makam P, Kannan T. 2-Aminothiazole derivatives as antimycobacterial agents: Synthesis, characterization, in vitro and in silico studies. Eur J Med Chem 2014; 87:643-56. [DOI: 10.1016/j.ejmech.2014.09.086] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 06/21/2014] [Accepted: 09/09/2014] [Indexed: 10/24/2022]
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25
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Schmitt N, Grunnet M, Olesen SP. Cardiac potassium channel subtypes: new roles in repolarization and arrhythmia. Physiol Rev 2014; 94:609-53. [PMID: 24692356 DOI: 10.1152/physrev.00022.2013] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K+ channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K+ channels drive the late repolarization of the ventricle with some redundancy, and in atria this repolarization reserve is supplemented by the fairly atrial-specific KV1.5, Kir3, KCa, and K2P channels. The role of the latter two subtypes in atria is currently being clarified, and several findings indicate that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K+ channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure. The underlying posttranscriptional and posttranslational remodeling of the individual K+ channels changes their activity and significance relative to each other, and they must be viewed together to understand their role in keeping a stable heart rhythm, also under menacing conditions like attacks of reentry arrhythmia.
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26
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Skibsbye L, Poulet C, Diness JG, Bentzen BH, Yuan L, Kappert U, Matschke K, Wettwer E, Ravens U, Grunnet M, Christ T, Jespersen T. Small-conductance calcium-activated potassium (SK) channels contribute to action potential repolarization in human atria. Cardiovasc Res 2014; 103:156-67. [PMID: 24817686 DOI: 10.1093/cvr/cvu121] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AIMS Small-conductance calcium-activated potassium (SK) channels are expressed in the heart of various species, including humans. The aim of the present study was to address whether SK channels play a functional role in human atria. METHODS AND RESULTS Quantitative real-time PCR analyses showed higher transcript levels of SK2 and SK3 than that of the SK1 subtype in human atrial tissue. SK2 and SK3 were reduced in chronic atrial fibrillation (AF) compared with sinus rhythm (SR) patients. Immunohistochemistry using confocal microscopy revealed widespread expression of SK2 in atrial myocytes. Two SK channel inhibitors (NS8593 and ICAGEN) were tested in heterologous expression systems revealing ICAGEN as being highly selective for SK channels, while NS8593 showed less selectivity for these channels. In isolated atrial myocytes from SR patients, both inhibitors decreased inwardly rectifying K(+) currents by ∼15% and prolonged action potential duration (APD), but no effect was observed in myocytes from AF patients. In trabeculae muscle strips from right atrial appendages of SR patients, both compounds increased APD and effective refractory period, and depolarized the resting membrane potential, while only NS8593 induced these effects in tissue from AF patients. SK channel inhibition did not alter any electrophysiological parameter in human interventricular septum tissue. CONCLUSIONS SK channels are present in human atria where they participate in repolarization. SK2 and SK3 were down-regulated and had reduced functional importance in chronic AF. As SK current was not found to contribute substantially to the ventricular AP, pharmacological inhibition of SK channels may be a putative atrial-selective target for future antiarrhythmic drug therapy.
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Affiliation(s)
- Lasse Skibsbye
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Claire Poulet
- Department of Pharmacology and Toxicology, Medical Faculty, Technical University Dresden, Dresden, Germany
| | - Jonas Goldin Diness
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark Acesion Pharma ApS, Ole Maaløes Vej 3, Copenhagen DK-2200, Denmark
| | - Bo Hjorth Bentzen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark Acesion Pharma ApS, Ole Maaløes Vej 3, Copenhagen DK-2200, Denmark
| | - Lei Yuan
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Utz Kappert
- Clinic for Cardiac Surgery, Heart Center Dresden, Medical Faculty, Dresden University of Technology, Dresden, Germany
| | - Klaus Matschke
- Clinic for Cardiac Surgery, Heart Center Dresden, Medical Faculty, Dresden University of Technology, Dresden, Germany
| | - Erich Wettwer
- Department of Pharmacology and Toxicology, Medical Faculty, Technical University Dresden, Dresden, Germany
| | - Ursula Ravens
- Department of Pharmacology and Toxicology, Medical Faculty, Technical University Dresden, Dresden, Germany
| | - Morten Grunnet
- Acesion Pharma ApS, Ole Maaløes Vej 3, Copenhagen DK-2200, Denmark
| | - Torsten Christ
- Department of Pharmacology and Toxicology, Medical Faculty, Technical University Dresden, Dresden, Germany Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas Jespersen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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27
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Cardiac ion channels and mechanisms for protection against atrial fibrillation. Rev Physiol Biochem Pharmacol 2013; 162:1-58. [PMID: 21987061 DOI: 10.1007/112_2011_3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Atrial fibrillation (AF) is recognised as the most common sustained cardiac arrhythmia in clinical practice. Ongoing drug development is aiming at obtaining atrial specific effects in order to prevent pro-arrhythmic, devastating ventricular effects. In principle, this is possible due to a different ion channel composition in the atria and ventricles. The present text will review the aetiology of arrhythmias with focus on AF and include a description of cardiac ion channels. Channels that constitute potentially atria-selective targets will be described in details. Specific focus is addressed to the recent discovery that Ca(2+)-activated small conductance K(+) channels (SK channels) are important for the repolarisation of atrial action potentials. Finally, an overview of current pharmacological treatment of AF is included.
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28
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Yang D, Arifhodzic L, Ganellin CR, Jenkinson DH. Further studies on bis-charged tetraazacyclophanes as potent inhibitors of small conductance Ca(2+)-activated K+ channels. Eur J Med Chem 2013; 63:907-23. [PMID: 23685886 DOI: 10.1016/j.ejmech.2013.02.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 02/21/2013] [Accepted: 02/22/2013] [Indexed: 11/20/2022]
Abstract
Previously, quinolinium-based tetraazacyclophanes, such as UCL 1684 and UCL 1848, have been shown to be extraordinarily sensitive to changes in chemical structure (especially to the size of the cyclophane system) with respect to activity as potent non-peptidic blockers of the small conductance Ca(2+)-activated K(+) ion channels (SKCa). The present work has sought to optimize the structure of the linking chains in UCL 1848. We report the synthesis and SKCa channel-blocking activity of 29 analogues of UCL 1848 in which the central CH2 of UCL 1848 is replaced by other groups X or Y = O, S, CF2, CO, CHOH, CC, CHCH, CHMe to explore whether subtle changes in bond length or flexibility can improve potency still further. The possibility of improving potency by introducing ring substituents has also been explored by synthesizing and testing 25 analogues of UCL 1684 and UCL 1848 with substituents (NO2, NH2, CF3, F, Cl, CH3, OCH3, OCF3, OH) in the 5, 6 or 7 positions of the aminoquinolinium rings. As in our earlier work, each compound was assayed for inhibition of the afterhyperpolarization (AHP) in rat sympathetic neurons, an action mediated by the SK3 subtype of the SKCa channel. One of the new compounds (39, R(7) = Cl, UCL 2053) is twice as potent as UCL 1848 and UCL 1684: seven are comparable in activity.
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Affiliation(s)
- Donglai Yang
- Department of Chemistry, University College London, Gower Street, London WC1E 6BT, UK
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29
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Cuconati A, Mills C, Goddard C, Zhang X, Yu W, Guo H, Xu X, Block TM. Suppression of AKT anti-apoptotic signaling by a novel drug candidate results in growth arrest and apoptosis of hepatocellular carcinoma cells. PLoS One 2013; 8:e54595. [PMID: 23355882 PMCID: PMC3552860 DOI: 10.1371/journal.pone.0054595] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 12/13/2012] [Indexed: 12/31/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the third most common cause of cancer fatalities worldwide, with limited treatment options and five year survival rates of between <5 and 15%. To address this medical need, we conducted a screen of a drug-like small molecule library for HCC-selective cytotoxins. We report here the identification of a disubstituted aminothiazole termed HBF-0079, with remarkable selective toxicity for HCC-derived cell lines versus non-HCC liver lines and most other cancer lines. HBF-0079 caused irreversible growth arrest and apoptosis of the HCC lines Huh7, Hep3B, HepaRG as well as the hepatoblastoma line HepG2, with CC50 values from ∼0.7−7.7 µM, while more than 45 µM was needed to achieve CC50 values for the immortalized normal hepatocyte lines THLE-2 and PH5CH. Of the sixty cancer lines from the National Cancer Institute panel, only five exhibited >50% growth inhibition by HBF-0079. In Huh7 cells, HBF-0079 induced cell cycle arrest in G1 and concomitant apoptosis, and its effects were irreversible after removal of the compound. These observations corroborate a loss of AKT phosphorylation at the mTORC2-targeted residue S473, with concurrent loss of phosphorylation of the mTORC1 targets SK6 and 4EBP1 in Huh7 but not PH5CH cells. Finally, growth of Hep3B-derived tumors in a murine xenograft model was significantly repressed by the compound through either systemic or intratumoral administration of formulated HBF-0079. The potential for development of this drug candidate is discussed.
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Affiliation(s)
- Andrea Cuconati
- Institute for Hepatitis and Virus Research, Hepatitis B Foundation, Doylestown, Pennsylvania, United States of America
- * E-mail: (AC); (TB)
| | - Courtney Mills
- Institute for Hepatitis and Virus Research, Hepatitis B Foundation, Doylestown, Pennsylvania, United States of America
| | - Cally Goddard
- Institute for Hepatitis and Virus Research, Hepatitis B Foundation, Doylestown, Pennsylvania, United States of America
| | - Xianchao Zhang
- Drexel Institute for Biotechnology and Virology Research, Drexel University College of Medicine, Doylestown, Pennsylvania, United States of America
| | - Wenquan Yu
- Institute for Hepatitis and Virus Research, Hepatitis B Foundation, Doylestown, Pennsylvania, United States of America
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, People’s Republic of China
| | - Haitao Guo
- Drexel Institute for Biotechnology and Virology Research, Drexel University College of Medicine, Doylestown, Pennsylvania, United States of America
| | - Xiaodong Xu
- Institute for Hepatitis and Virus Research, Hepatitis B Foundation, Doylestown, Pennsylvania, United States of America
- Enantigen Therapeutics, Incorporated, Doylestown, Pennsylvania, United States of America
| | - Timothy M. Block
- Institute for Hepatitis and Virus Research, Hepatitis B Foundation, Doylestown, Pennsylvania, United States of America
- Drexel Institute for Biotechnology and Virology Research, Drexel University College of Medicine, Doylestown, Pennsylvania, United States of America
- * E-mail: (AC); (TB)
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30
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Klein MT, Vinson PN, Niswender CM. Approaches for probing allosteric interactions at 7 transmembrane spanning receptors. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 115:1-59. [PMID: 23415091 PMCID: PMC5482179 DOI: 10.1016/b978-0-12-394587-7.00001-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In recent years, allosteric modulation of 7 transmembrane spanning receptors (7TMRs) has become a highly productive and exciting field of receptor pharmacology and drug discovery efforts. Positive and negative allosteric modulators (PAMs and NAMs, respectively) present a number of pharmacological and therapeutic advantages over conventional orthosteric ligands, including improved receptor-subtype selectivity, a lower propensity to induce receptor desensitization, the preservation of endogenous temporal and spatial activation of receptors, greater chemical flexibility for optimization of drug metabolism and pharmacokinetic parameters, and saturability of effect at target receptors, thus improving safety concerns and risk of overdose. Additionally, the relatively new concept of allosteric modulator-mediated receptor signal bias opens up a number of intriguing possibilities for PAMs, NAMs, and allosteric agonists, including the potential to selectively activate therapeutically beneficial signaling cascades, which could yield a superior tissue selectivity and side effect profile of allosteric modulators. However, there are a number of considerations and caveats that must be addressed when screening for and characterizing the properties of 7TMR allosteric modulators. Mode of pharmacology, methodology used to monitor receptor activity, detection of appropriate downstream analytes, selection of orthosteric probe, and assay time-course must all be considered when implementing any high-throughput screening campaign or when characterizing the properties of active compounds. Yet compared to conventional agonist/antagonist drug discovery programs, these elements of assay design are often a great deal more complicated when working with 7TMRs allosteric modulators. Moreover, for classical pharmacological methodologies and analyses, like radioligand binding and the assessment of compound affinity, the properties of allosteric modulators yield data that are more nuanced than orthosteric ligand-receptor interactions. In this review, we discuss the current methodologies being used to identify and characterize allosteric modulators, lending insight into the approaches that have been most successful in accurately and robustly identifying hit compounds. New label-free technologies capable of detecting phenotypic cellular changes in response to receptor activation are powerful tools well suited for assessing subtle or potentially masked cellular responses to allosteric modulation of 7TMRs. Allosteric modulator-induced receptor signal bias and the assay systems available to probe the various downstream signaling outcomes of receptor activation are also discussed.
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Affiliation(s)
- Michael T Klein
- Department of Pharmacology, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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31
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Small-molecule modulators of inward rectifier K+ channels: recent advances and future possibilities. Future Med Chem 2011; 2:757-74. [PMID: 20543968 DOI: 10.4155/fmc.10.179] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Inward rectifier potassium (Kir) channels have been postulated as therapeutic targets for several common disorders including hypertension, cardiac arrhythmias and pain. With few exceptions, however, the small-molecule pharmacology of this family is limited to nonselective cardiovascular and neurologic drugs with off-target activity toward inward rectifiers. Consequently, the actual therapeutic potential and 'drugability' of most Kir channels has not yet been determined experimentally. The purpose of this review is to provide a comprehensive summary of publicly disclosed Kir channel small-molecule modulators and highlight recent targeted drug-discovery efforts toward Kir1.1 and Kir2.1. The review concludes with a brief speculation on how the field of Kir channel pharmacology will develop over the coming years and a discussion of the increasingly important role academic laboratories will play in this progress.
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Diness JG, Sørensen US, Nissen JD, Al-Shahib B, Jespersen T, Grunnet M, Hansen RS. Inhibition of Small-Conductance Ca
2+
-Activated K
+
Channels Terminates and Protects Against Atrial Fibrillation. Circ Arrhythm Electrophysiol 2010; 3:380-90. [DOI: 10.1161/circep.110.957407] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Recently, evidence has emerged that small-conductance Ca
2+
-activated K
+
(SK) channels are predominantly expressed in the atria in a number of species including human. In rat, guinea pig, and rabbit ex vivo and in vivo models of atrial fibrillation (AF), we used 3 different SK channel inhibitors, UCL1684,
N
-(pyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (ICA), and NS8593, to assess the hypothesis that pharmacological inhibition of SK channels is antiarrhythmic.
Methods and Results—
In isolated, perfused guinea pig hearts, AF could be induced in all control hearts (n=7) with a combination of 1 μmol/L acetylcholine combined with electric stimulation. Pretreatment with 3 μmol/L NS8593, which had no effect on QT interval, prolonged the atrial effective refractory period by 37.1±7.7% (
P
<0.001) and prevented acetylcholine-induced AF (
P
<0.001, n=7). After AF induction, perfusion with NS8593 (10 μmol/L), UCL1684 (1 μmol/L), or ICA (1 μmol/L) terminated AF in all hearts, comparable to 10 μmol/L amiodarone. In isolated, perfused rat hearts, AF was induced with electric stimulation; 10 μmol/L NS8593 terminated AF and prevented reinduction of AF in all hearts (n=6,
P
<0.001). In all hearts, AF could be reinduced after washing. In isolated, perfused rabbit hearts, AF was induced with 10 μmol/L acetylcholine and burst pacing; 10 μmol/L NS8593 terminated AF and prevented reinduction of AF in all hearts (n=6,
P
<0.001). After washing, AF could be reinduced in 75% of the hearts (n=4,
P
=0.06). In an in vivo rat model of acute AF induced by burst pacing, injection of 5 mg/kg of either NS8593 or amiodarone shortened AF duration significantly to (23.2±20.0%,
P
<0.001, n=5, and 26.2±17.9%,
P
<0.001, n=5, respectively) as compared with injection of vehicle (96.3±33.2%, n=5).
Conclusions—
Inhibition of SK channels prolongs atrial effective refractory period without affecting QT interval and prevents and terminates AF ex vivo and in vivo, thus offering a promising new therapeutic opportunity in the treatment of AF.
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Affiliation(s)
- Jonas Goldin Diness
- From NeuroSearch A/S (J.G.D., U.S.S., B.A.-S., M.G., R.S.H.), Ballerup, Denmark; and the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.G.D., J.D.N., T.J., M.G.), Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulrik S. Sørensen
- From NeuroSearch A/S (J.G.D., U.S.S., B.A.-S., M.G., R.S.H.), Ballerup, Denmark; and the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.G.D., J.D.N., T.J., M.G.), Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jakob Dahl Nissen
- From NeuroSearch A/S (J.G.D., U.S.S., B.A.-S., M.G., R.S.H.), Ballerup, Denmark; and the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.G.D., J.D.N., T.J., M.G.), Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Baha Al-Shahib
- From NeuroSearch A/S (J.G.D., U.S.S., B.A.-S., M.G., R.S.H.), Ballerup, Denmark; and the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.G.D., J.D.N., T.J., M.G.), Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Jespersen
- From NeuroSearch A/S (J.G.D., U.S.S., B.A.-S., M.G., R.S.H.), Ballerup, Denmark; and the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.G.D., J.D.N., T.J., M.G.), Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Grunnet
- From NeuroSearch A/S (J.G.D., U.S.S., B.A.-S., M.G., R.S.H.), Ballerup, Denmark; and the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.G.D., J.D.N., T.J., M.G.), Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rie Schultz Hansen
- From NeuroSearch A/S (J.G.D., U.S.S., B.A.-S., M.G., R.S.H.), Ballerup, Denmark; and the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.G.D., J.D.N., T.J., M.G.), Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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33
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Preliminary SAR studies on non-apamin-displacing 4-(aminomethylaryl)pyrrazolopyrimidine K(Ca) channel blockers. Bioorg Med Chem Lett 2008; 18:5694-7. [PMID: 18824351 DOI: 10.1016/j.bmcl.2008.08.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 08/07/2008] [Accepted: 08/08/2008] [Indexed: 11/22/2022]
Abstract
An exploratory SAR study on a series of potent, non-apamin-displacing 4-(aminomethylaryl)pyrazolopyrimidine K(Ca) channel blockers is described and their selectivity against K(Ca) channel subtypes is reported. The most potent analog, 5-chloro-N-(thiophen-2-ylmethyl)pyrazolo[1,5-a]pyrimidin-7-amine (24) displayed sub-micromolar activity in both a thallium flux and whole-cell electrophysiology assay and did not displace apamin in a competitive binding study.
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