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1.
J Med Chem ; 64(8): 4709-4729, 2021 04 22.
Artigo em Inglês | MEDLINE | ID: mdl-33797924

RESUMO

We describe the discovery of histone deacetylase (HDACs) 1, 2, and 3 inhibitors with ethyl ketone as the zinc-binding group. These HDACs 1, 2, and 3 inhibitors have good enzymatic and cellular activity. Their serum shift in cellular potency has been minimized, and selectivity against hERG has been improved. They are also highly selective over HDACs 6 and 8. These inhibitors contain a variety of substituted heterocycles on the imidazole or oxazole scaffold. Compounds 31 and 48 stand out due to their good potency, high selectivity over HDACs 6 and 8, reduced hERG activity, optimized serum shift in cellular potency, and good rat and dog PK profiles.


Assuntos
Canal de Potássio ERG1/metabolismo , HIV-1/fisiologia , Inibidores de Histona Desacetilases/química , Histona Desacetilases/metabolismo , Cetonas/química , Animais , Cães , Avaliação Pré-Clínica de Medicamentos , Meia-Vida , Histona Desacetilase 1/antagonistas & inibidores , Histona Desacetilase 1/metabolismo , Histona Desacetilase 2/antagonistas & inibidores , Histona Desacetilase 2/metabolismo , Inibidores de Histona Desacetilases/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Histona Desacetilases/química , Humanos , Imidazóis/química , Oxazóis/química , Isoformas de Proteínas/antagonistas & inibidores , Isoformas de Proteínas/metabolismo , Ratos , Relação Estrutura-Atividade , Ativação Viral/efeitos dos fármacos
2.
J Pharmacol Exp Ther ; 377(2): 265-272, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33674391

RESUMO

Drug-induced long QT syndrome (LQTS) is an established cardiac side effect of a wide range of medications and represents a significant concern for drug safety. The rapidly and slowly activating delayed rectifier K+ currents, mediated by channels encoded by the human ether-a-go-go-related gene (hERG) and KCNQ1 + KCNE1, respectively, are two main currents responsible for ventricular repolarization. The common cause for drugs to induce LQTS is through impairing the hERG channel. For the recent emergence of COVID-19, caused by severe acute respiratory syndrome coronavirus 2, several drugs have been investigated as potential therapies; however, there are concerns about their QT prolongation risk. Here, we studied the effects of chloroquine, hydroxychloroquine, azithromycin, and remdesivir on hERG channels. Our results showed that although chloroquine acutely blocked hERG current (IhERG), with an IC50 of 3.0 µM, hydroxychloroquine acutely blocked IhERG 8-fold less potently, with an IC50 of 23.4 µM. Azithromycin and remdesivir did not acutely affect IhERG When these drugs were added at 10 µM to the cell culture medium for 24 hours, remdesivir increased IhERG by 2-fold, which was associated with an increased mature hERG channel expression. In addition, these four drugs did not acutely or chronically affect KCNQ1 + KCNE1 channels. Our data provide insight into COVID-19 drug-associated LQTS and cardiac safety concerns. SIGNIFICANCE STATEMENT: This work demonstrates that, among off-label potential COVID-19 treatment drugs chloroquine, hydroxychloroquine, azithromycin, and remdesivir, the former two drugs block hERG potassium channels, whereas the latter two drugs do not. All four drugs do not affect KCNQ1 + KCNE1. As hERG and KCNQ1 + KCNE1 are two main K+ channels responsible for ventricular repolarization, and most drugs that induce long QT syndrome (LQTS) do so by impairing hERG channels, these data provide insight into COVID-19 drug-associated LQTS and cardiac safety concerns.


Assuntos
Monofosfato de Adenosina/análogos & derivados , Alanina/análogos & derivados , Azitromicina/farmacologia , COVID-19/tratamento farmacológico , Cloroquina/farmacologia , Canal de Potássio ERG1/antagonistas & inibidores , Hidroxicloroquina/farmacologia , Monofosfato de Adenosina/farmacologia , Monofosfato de Adenosina/uso terapêutico , Alanina/farmacologia , Alanina/uso terapêutico , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Antivirais/farmacologia , Antivirais/uso terapêutico , Azitromicina/uso terapêutico , COVID-19/metabolismo , Cloroquina/uso terapêutico , Relação Dose-Resposta a Droga , Canal de Potássio ERG1/metabolismo , Células HEK293 , Humanos , Hidroxicloroquina/uso terapêutico , Bloqueadores dos Canais de Potássio/farmacologia , Bloqueadores dos Canais de Potássio/uso terapêutico
3.
Eur J Pharmacol ; 899: 174030, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33727059

RESUMO

The cardiac action potential is regulated by several ion channels. Drugs capable to block these channels, in particular the human ether-à-go-go-related gene (hERG) channel, also known as KV11.1 channel, may lead to a potentially lethal ventricular tachyarrhythmia called "Torsades de Pointes". Thus, evaluation of the hERG channel off-target activity of novel chemical entities is nowadays required to safeguard patients as well as to avoid attrition in drug development. Flavonoids, a large class of natural compounds abundantly present in food, beverages, herbal medicines, and dietary food supplements, generally escape this assessment, though consumed in consistent amounts. Continuously growing evidence indicates that these compounds may interact with the hERG channel and block it. The present review, by examining numerous studies, summarizes the state-of-the-art in this field, describing the most significant examples of direct and indirect inhibition of the hERG channel current operated by flavonoids. A description of the molecular interactions between a few of these natural molecules and the Rattus norvegicus channel protein, achieved by an in silico approach, is also presented.


Assuntos
Canal de Potássio ERG1/antagonistas & inibidores , Flavonoides/toxicidade , Frequência Cardíaca/efeitos dos fármacos , Síndrome do QT Longo/induzido quimicamente , Miócitos Cardíacos/efeitos dos fármacos , Bloqueadores dos Canais de Potássio/toxicidade , Torsades de Pointes/induzido quimicamente , Potenciais de Ação , Animais , Canal de Potássio ERG1/química , Canal de Potássio ERG1/metabolismo , Humanos , Síndrome do QT Longo/metabolismo , Síndrome do QT Longo/fisiopatologia , Miócitos Cardíacos/metabolismo , Conformação Proteica , Medição de Risco , Fatores de Risco , Relação Estrutura-Atividade , Torsades de Pointes/metabolismo , Torsades de Pointes/fisiopatologia
4.
Chem Biol Interact ; 338: 109425, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33617802

RESUMO

Non-steroidal Anti-inflammatory Drugs (NSAIDs) are widely used because of their excellent anti-inflammatory and analgesic effects. However, NSAIDs could cause certain cardiac side effects, such as myocardial infarction, heart failure, atrial fibrillation, arrhythmia and sudden cardiac death. Therefore, meloxicam, nimesulide, piroxicam, and diclofenac were selected and the whole cell patch clamp technique was used to investigate the electrophysiological regulatory effects of them on the sodium channel hNav1.5 and potassium channel hKv11.1, which were closely associated to the biotoxicity of cardiac, and to explore the potential cardiac risk mechanism. The results showed that the four NSAIDs could inhibit the peak currents of hNav1.5 and hKv11.1. Furthermore, the four NSAIDs could affect both the activation and inactivation processes of hNav1.5 with I-V curves left-shifted to hyperpolarized direction in activation phase. These data indicate that the inhibition effects of Nav1.5 and Kv11.1 by meloxicam, nimesulide, piroxicam, and diclofenac might contribute to their potential cardiac risk. These findings provide a basis for the discovery of other potential cardiac risk targets for NSAIDs.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Canal de Potássio ERG1/metabolismo , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Animais , Anti-Inflamatórios não Esteroides/química , Células CHO , Cricetulus , Células HEK293 , Humanos , Ativação do Canal Iônico/efeitos dos fármacos , Cinética
5.
Int J Mol Sci ; 22(2)2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33467093

RESUMO

The Kv11.1 voltage-gated potassium channel, encoded by the KCNH2 gene, conducts the rapidly activating delayed rectifier current in the heart. KCNH2 pre-mRNA undergoes alternative polyadenylation to generate two C-terminal Kv11.1 isoforms in the heart. Utilization of a poly(A) signal in exon 15 produces the full-length, functional Kv11.1a isoform, while intron 9 polyadenylation generates the C-terminally truncated, nonfunctional Kv11.1a-USO isoform. The relative expression of Kv11.1a and Kv11.1a-USO isoforms plays an important role in the regulation of Kv11.1 channel function. In this study, we tested the hypothesis that the RNA polyadenylate binding protein nuclear 1 (PABPN1) interacts with a unique 22 nt adenosine stretch adjacent to the intron 9 poly(A) signal and regulates KCNH2 pre-mRNA alternative polyadenylation and the relative expression of Kv11.1a C-terminal isoforms. We showed that PABPN1 inhibited intron 9 poly(A) activity using luciferase reporter assays, tandem poly(A) reporter assays, and RNA pulldown assays. We also showed that PABPN1 increased the relative expression level of the functional Kv11.1a isoform using RNase protection assays, immunoblot analyses, and patch clamp recordings. Our present findings suggest a novel role for the RNA-binding protein PABPN1 in the regulation of functional and nonfunctional Kv11.1 isoform expression.


Assuntos
Canal de Potássio ERG1/genética , Proteína I de Ligação a Poli(A)/metabolismo , Canal de Potássio ERG1/metabolismo , Células HEK293 , Humanos , Poliadenilação , Ligação Proteica , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo
6.
Nat Commun ; 12(1): 150, 2021 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-33420011

RESUMO

Novel bacterial type II topoisomerase inhibitors (NBTIs) stabilize single-strand DNA cleavage breaks by DNA gyrase but their exact mechanism of action has remained hypothetical until now. We have designed a small library of NBTIs with an improved DNA gyrase-binding moiety resulting in low nanomolar inhibition and very potent antibacterial activity. They stabilize single-stranded cleavage complexes and, importantly, we have obtained the crystal structure where an NBTI binds gyrase-DNA in a single conformation lacking apparent static disorder. This directly proves the previously postulated NBTI mechanism of action and shows that they stabilize single-strand cleavage through asymmetric intercalation with a shift of the scissile phosphate. This crystal stucture shows that the chlorine forms a halogen bond with the backbone carbonyls of the two symmetry-related Ala68 residues. To the best of our knowledge, such a so-called symmetrical bifurcated halogen bond has not been identified in a biological system until now.


Assuntos
Antibacterianos/farmacologia , Cloro/metabolismo , DNA Girase/metabolismo , Inibidores da Topoisomerase II/farmacologia , Alanina/química , Alanina/metabolismo , Antibacterianos/química , Cristalografia por Raios X , DNA Girase/química , DNA Topoisomerases Tipo II , DNA de Cadeia Simples/metabolismo , Desenho de Fármacos , Canal de Potássio ERG1/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Células Hep G2 , Células Endoteliais da Veia Umbilical Humana , Humanos , Concentração Inibidora 50 , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Proteínas de Ligação a Poli-ADP-Ribose/antagonistas & inibidores , Quinolinas/química , Quinolinas/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/enzimologia , Inibidores da Topoisomerase II/química
7.
Biophys J ; 120(4): 738-748, 2021 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-33476597

RESUMO

The human-ether-a-go-go-related gene (hERG) encodes the voltage-gated potassium channel (KCNH2 or Kv11.1, commonly known as hERG). This channel plays a pivotal role in the stability of phase 3 repolarization of the cardiac action potential. Although a high-resolution cryo-EM structure is available for its depolarized (open) state, the structure surprisingly did not feature many functionally important interactions established by previous biochemical and electrophysiology experiments. Using molecular dynamics flexible fitting (MDFF), we refined the structure and recovered the missing functionally relevant salt bridges in hERG in its depolarized state. We also performed electrophysiology experiments to confirm the functional relevance of a novel salt bridge predicted by our refinement protocol. Our work shows how refinement of a high-resolution cryo-EM structure helps to bridge the existing gap between the structure and function in the voltage-sensing domain (VSD) of hERG.


Assuntos
Canais de Potássio Éter-A-Go-Go , Simulação de Dinâmica Molecular , Potenciais de Ação , Microscopia Crioeletrônica , Canal de Potássio ERG1/metabolismo , Canais de Potássio Éter-A-Go-Go/metabolismo , Humanos
8.
Am J Physiol Heart Circ Physiol ; 319(2): H251-H261, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32559136

RESUMO

Human ether-à-go-go related gene (hERG) K+ channels are important in cardiac repolarization, and their dysfunction causes prolongation of the ventricular action potential, long QT syndrome, and arrhythmia. As such, approaches to augment hERG channel function, such as activator compounds, have been of significant interest due to their marked therapeutic potential. Activator compounds that hinder channel inactivation abbreviate action potential duration (APD) but carry risk of overcorrection leading to short QT syndrome. Enhanced risk by overcorrection of the APD may be tempered by activator-induced increased refractoriness; however, investigation of the cumulative effect of hERG activator compounds on the balance of these effects in whole organ systems is lacking. Here, we have investigated the antiarrhythmic capability of a hERG activator, RPR260243, which primarily augments channel function by slowing deactivation kinetics in ex vivo zebrafish whole hearts. We show that RPR260243 abbreviates the ventricular APD, reduces triangulation, and steepens the slope of the electrical restitution curve. In addition, RPR260243 increases the post-repolarization refractory period. We provide evidence that this latter effect arises from RPR260243-induced enhancement of hERG channel-protective currents flowing early in the refractory period. Finally, the cumulative effect of RPR260243 on arrhythmogenicity in whole organ zebrafish hearts is demonstrated by the restoration of normal rhythm in hearts presenting dofetilide-induced arrhythmia. These findings in a whole organ model demonstrate the antiarrhythmic benefit of hERG activator compounds that modify both APD and refractoriness. Furthermore, our results demonstrate that targeted slowing of hERG channel deactivation and enhancement of protective currents may provide an effective antiarrhythmic approach.NEW & NOTEWORTHY hERG channel dysfunction causes long QT syndrome and arrhythmia. Activator compounds have been of significant interest due to their therapeutic potential. We used the whole organ zebrafish heart model to demonstrate the antiarrhythmic benefit of the hERG activator, RPR260243. The activator abbreviated APD and increased refractoriness, the combined effect of which rescued induced ventricular arrhythmia. Our findings show that the targeted slowing of hERG channel deactivation and enhancement of protective currents caused by the RPR260243 activator may provide an effective antiarrhythmic approach.


Assuntos
Antiarrítmicos/farmacologia , Arritmias Cardíacas/prevenção & controle , Canal de Potássio ERG1/agonistas , Canais de Potássio Éter-A-Go-Go/agonistas , Frequência Cardíaca/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Piperidinas/farmacologia , Quinolinas/farmacologia , Proteínas de Peixe-Zebra/agonistas , Potenciais de Ação , Animais , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/fisiopatologia , Modelos Animais de Doenças , Canal de Potássio ERG1/genética , Canal de Potássio ERG1/metabolismo , Canais de Potássio Éter-A-Go-Go/metabolismo , Cinética , Miócitos Cardíacos/metabolismo , Oócitos , Período Refratário Eletrofisiológico , Transdução de Sinais , Xenopus laevis , Peixe-Zebra , Proteínas de Peixe-Zebra/metabolismo
9.
Biochem Biophys Res Commun ; 526(4): 1085-1091, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32321643

RESUMO

The human Ether-à-go-go Related Gene (hERG) encodes a potassium channel responsible for the cardiac rapid delayed rectifier K+ current, IKr, which regulates ventricular repolarization. Loss-of-function hERG mutations underpin the LQT2 form of congenital long QT syndrome. This study was undertaken to elucidate the functional consequences of a variant of uncertain significance, T634S, located at a highly conserved position at the top of the S6 helix of the hERG channel. Whole-cell patch-clamp recordings were made at 37 °C of hERG current (IhERG) from HEK 293 cells expressing wild-type (WT) hERG, WT+T634S and hERG-T634S alone. When the T634S mutation was expressed alone little or no IhERG could be recorded. Co-expressing WT and hERG-T634S suppressed IhERG tails by ∼57% compared to WT alone, without significant alteration of voltage dependent activation of IhERG. A similar suppression of IhERG was observed under action potential voltage clamp. Comparable reduction of IKr in a ventricular AP model delayed repolarization and led to action potential prolongation. A LI-COR® based On/In-Cell Western assay showed that cell surface expression of hERG channels in HEK 293 cells was markedly reduced by the T634S mutation, whilst total cellular hERG expression was unaffected, demonstrating impaired trafficking of the hERG-T634S mutant. Incubation with E-4031, but not lumacaftor, rescued defective hERG-T634S channel trafficking and IhERG density. In conclusion, these data identify hERG-T634S as a rescuable trafficking defective mutation that reduces IKr sufficiently to delay repolarization and, thereby, potentially produce a LQT2 phenotype.


Assuntos
Sequência Conservada , Canal de Potássio ERG1/genética , Canal de Potássio ERG1/metabolismo , Mutação com Perda de Função/genética , Serina/genética , Treonina/genética , Potenciais de Ação , Sequência de Aminoácidos , Canal de Potássio ERG1/química , Humanos , Ativação do Canal Iônico , Transporte Proteico
10.
Mol Pharmacol ; 98(4): 508-517, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32321735

RESUMO

Human ether-a-go-go-related gene (hERG) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium current (IKr) important for repolarization of cardiac action potentials. Drug-induced disruption of hERG channel function is a main cause of acquired long QT syndrome, which can lead to ventricular arrhythmias and sudden death. Illicit fentanyl use is associated with sudden death. We have demonstrated that fentanyl blocks hERG current (IhERG) at concentrations that overlap with the upper range of postmortem blood concentrations in fentanyl-related deaths. Since fentanyl can cause respiratory depression and electrolyte imbalances, in the present study we investigated whether certain pathologic circumstances exacerbate fentanyl-induced block of IhERG Our results show that chronic hypoxia or hypokalemia additively reduced IhERG with fentanyl. As well, high pH potentiated the fentanyl-mediated block of hERG channels, with an IC50 at pH 8.4 being 7-fold lower than that at pH 7.4. Furthermore, although the full-length hERG variant, hERG1a, has been widely used to study hERG channels, coexpression with the short variant, hERG1b (which does not produce current when expressed alone), produces functional hERG1a/1b channels, which gate more closely resembling native IKr Our results showed that fentanyl blocked hERG1a/1b channels with a 3-fold greater potency than hERG1a channels. Thus, in addition to a greater susceptibility due to the presence of hERG1b in the human heart, hERG channel block by fentanyl can be exacerbated by certain conditions, such as hypoxia, hypokalemia, or alkalosis, which may increase the risk of fentanyl-induced ventricular arrhythmias and sudden death. SIGNIFICANCE STATEMENT: This work demonstrates that heterologously expressed human ether a-go-go-related gene (hERG) 1a/1b channels, which more closely resemble rapidly activating delayed rectifier potassium current in the human heart, are blocked by fentanyl with a 3-fold greater potency than the previously studied hERG1a expressed alone. Additionally, chronic hypoxia, hypokalemia, and alkalosis can increase the block of hERG current by fentanyl, potentially increasing the risk of cardiac arrhythmias and sudden death.


Assuntos
Analgésicos Opioides/farmacologia , Canal de Potássio ERG1/genética , Canal de Potássio ERG1/metabolismo , Fentanila/farmacologia , Processamento Alternativo , Hipóxia Celular , Meios de Cultura/química , Canal de Potássio ERG1/antagonistas & inibidores , Células HEK293 , Humanos , Concentração de Íons de Hidrogênio , Concentração Inibidora 50 , Modelos Biológicos , Mutação , Potássio/metabolismo
11.
Biochim Biophys Acta Rev Cancer ; 1873(2): 188355, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32135169

RESUMO

The human ether-à-go-go related gene (HERG) encodes the alpha subunit of Kv11.1, which is a voltage-gated K+ channel protein mainly expressed in heart and brain tissue. HERG plays critical role in cardiac repolarization, and mutations in HERG can cause long QT syndrome. More recently, evidence has emerged that HERG channels are aberrantly expressed in many kinds of cancer cells and play important roles in cancer progression. HERG could therefore be a potential biomarker for cancer and a possible molecular target for anticancer drug design. HERG affects a number of cellular processes, including cell proliferation, apoptosis, angiogenesis and migration, any of which could be affected by dysregulation of HERG. This review provides an overview of available information on HERG channel as it relates to cancer, with focus on the mechanism by which HERG influences cancer progression. Molecular docking attempts suggest two possible protein-protein interactions of HERG with the ß1-integrin receptor and the transcription factor STAT-1 as novel HERG-directed therapeutic targeting which avoids possible cardiotoxicity. The role of epigenetics in regulating HERG channel expression and activity in cancer will also be discussed. Finally, given its inherent extracellular accessibility as an ion channel, we discuss regulatory roles of this molecule in cancer physiology and therapeutic potential. Future research should be directed to explore the possibilities of therapeutic interventions targeting HERG channels while minding possible complications.


Assuntos
Carcinogênese/patologia , Canal de Potássio ERG1/metabolismo , Integrina beta1/metabolismo , Neoplasias/patologia , Fator de Transcrição STAT1/metabolismo , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Apoptose/efeitos dos fármacos , Benzimidazóis/farmacologia , Benzimidazóis/uso terapêutico , Carcinogênese/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Canal de Potássio ERG1/antagonistas & inibidores , Canal de Potássio ERG1/química , Canal de Potássio ERG1/genética , Epigênese Genética/efeitos dos fármacos , Fluoxetina/farmacologia , Fluoxetina/uso terapêutico , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Síndrome do QT Longo/genética , Potenciais da Membrana/efeitos dos fármacos , Simulação de Acoplamento Molecular , Mutação , Miócitos Cardíacos/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/genética , Piperidinas/farmacologia , Piperidinas/uso terapêutico , Conformação Proteica em alfa-Hélice , Mapeamento de Interação de Proteínas , Estrutura Quaternária de Proteína , Piridinas/farmacologia , Piridinas/uso terapêutico , Transdução de Sinais/efeitos dos fármacos , Sulfanilamidas/farmacologia , Sulfanilamidas/uso terapêutico
12.
Int J Biochem Cell Biol ; 122: 105741, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32173522

RESUMO

The activation of the ß-adrenergic receptor (ß-AR) regulates the human ether a-go-go-related gene (HERG) channel via protein kinase A (PKA), which in turn induces lethal arrhythmia in patients with long QT syndromes (LQTS). However, the role of A-kinase anchoring proteins (AKAPs) in PKA's regulation of the HERG channel and its molecular mechanism are not clear. Here, HEK293 cells were transfected with the HERG gene alone or co-transfected with HERG and AKAP5 using Lipofectamine 2000. Western blotting was performed to determine HERG protein expression, and immunofluorescence and immunoprecipitation were used to assess the binding and cellular colocalization of HERG, AKAP5, and PKA. The HEK293-HERG and HEK293-HERG + AKAP5 cells were treated with forskolin at different concentrations and different time. HERG protein expression significantly increased under all treatment conditions (P < 0.001). The level of HERG protein expression in HEK293-HERG + AKAP5 cells was higher than that observed in HEK293-HERG cells (P < 0.001). Immunofluorescence and immunoprecipitation indicated that HERG bound to PKA and AKAP5 and was colocalized at the cell membrane. The HERG channel protein, AKAP5, and PKA interacted with each other and appeared to form intracellular complexes. These results provide evidence for a novel mechanism which AKAP5 anchors PKA to up-regulate the HERG channel protein.


Assuntos
Proteínas de Ancoragem à Quinase A/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Canal de Potássio ERG1/metabolismo , Cardiotônicos/farmacologia , Colforsina/farmacologia , Células HEK293 , Humanos , Síndrome do QT Longo/tratamento farmacológico , Síndrome do QT Longo/metabolismo , Transfecção , Regulação para Cima
13.
Circ Res ; 126(8): 947-964, 2020 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-32091972

RESUMO

RATIONALE: Drug-induced proarrhythmia is so tightly associated with prolongation of the QT interval that QT prolongation is an accepted surrogate marker for arrhythmia. But QT interval is too sensitive a marker and not selective, resulting in many useful drugs eliminated in drug discovery. OBJECTIVE: To predict the impact of a drug from the drug chemistry on the cardiac rhythm. METHODS AND RESULTS: In a new linkage, we connected atomistic scale information to protein, cell, and tissue scales by predicting drug-binding affinities and rates from simulation of ion channel and drug structure interactions and then used these values to model drug effects on the hERG channel. Model components were integrated into predictive models at the cell and tissue scales to expose fundamental arrhythmia vulnerability mechanisms and complex interactions underlying emergent behaviors. Human clinical data were used for model framework validation and showed excellent agreement, demonstrating feasibility of a new approach for cardiotoxicity prediction. CONCLUSIONS: We present a multiscale model framework to predict electrotoxicity in the heart from the atom to the rhythm. Novel mechanistic insights emerged at all scales of the system, from the specific nature of proarrhythmic drug interaction with the hERG channel, to the fundamental cellular and tissue-level arrhythmia mechanisms. Applications of machine learning indicate necessary and sufficient parameters that predict arrhythmia vulnerability. We expect that the model framework may be expanded to make an impact in drug discovery, drug safety screening for a variety of compounds and targets, and in a variety of regulatory processes.


Assuntos
Antiarrítmicos/química , Arritmias Cardíacas/tratamento farmacológico , Cardiotoxinas/química , Simulação por Computador , Descoberta de Drogas/métodos , Canal de Potássio ERG1/química , Antiarrítmicos/metabolismo , Antiarrítmicos/uso terapêutico , Arritmias Cardíacas/metabolismo , Cardiotoxicidade/metabolismo , Cardiotoxicidade/prevenção & controle , Cardiotoxinas/efeitos adversos , Cardiotoxinas/metabolismo , Descoberta de Drogas/tendências , Canal de Potássio ERG1/metabolismo , Feminino , Humanos , Síndrome do QT Longo/tratamento farmacológico , Síndrome do QT Longo/metabolismo , Aprendizado de Máquina , Masculino , Moxifloxacina/química , Moxifloxacina/metabolismo , Moxifloxacina/uso terapêutico , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/fisiologia , Fenetilaminas/química , Fenetilaminas/metabolismo , Fenetilaminas/uso terapêutico , Estrutura Secundária de Proteína , Sulfonamidas/química , Sulfonamidas/metabolismo , Sulfonamidas/uso terapêutico , Inibidores da Topoisomerase II/química , Inibidores da Topoisomerase II/metabolismo , Inibidores da Topoisomerase II/uso terapêutico
14.
Int J Mol Sci ; 21(4)2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-32093314

RESUMO

UCL-2077 (triphenylmethylaminomethyl)pyridine) was previously reported to suppress slow afterhyperpolarization in neurons. However, the information with respect to the effects of UCL-2077 on ionic currents is quite scarce. The addition of UCL-2077 decreased the amplitude of erg-mediated K+ current (IK(erg)) together with an increased deactivation rate of the current in pituitary GH3 cells. The IC50 and KD values of UCL-2077-induced inhibition of IK(erg) were 4.7 and 5.1 µM, respectively. UCL-2077 (10 µM) distinctly shifted the midpoint in the activation curve of IK(erg) to less hyperpolarizing potentials by 17 mV. Its presence decreased the degree of voltage hysteresis for IK(erg) elicitation by long-lasting triangular ramp pulse. It also diminished the probability of the opening of intermediate-conductance Ca2+-activated K+ channels. In cell-attached current recordings, UCL-2077 raised the frequency of action currents. When KCNH2 mRNA was knocked down, a UCL-2077-mediated increase in AC firing was attenuated. Collectively, the actions elaborated herein conceivably contribute to the perturbating effects of this compound on electrical behaviors of excitable cells.


Assuntos
Benzilaminas/farmacologia , Canal de Potássio ERG1/metabolismo , Potássio/metabolismo , Piridinas/farmacologia , Somatotrofos/metabolismo , Linhagem Celular , Canal de Potássio ERG1/genética , Técnicas de Silenciamento de Genes , Humanos , Transporte de Íons/efeitos dos fármacos , Transporte de Íons/genética , Somatotrofos/citologia
15.
J Med Chem ; 63(3): 1298-1312, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-31935327

RESUMO

Our previous efforts have led to the development of two potent NNRTIs, K-5a2 and 25a, exhibiting effective anti-HIV-1 potency and resistance profiles compared with etravirine. However, both inhibitors suffered from potent hERG inhibition and short half-life. In this article, with K-5a2 and etravirine as leads, series of novel fluorine-substituted diarylpyrimidine derivatives were designed via molecular hybridization and bioisosterism strategies. The results indicated 24b was the most active inhibitor, exhibiting broad-spectrum activity (EC50 = 3.60-21.5 nM) against resistant strains, significantly lower cytotoxicity (CC50= 155 µM), and reduced hERG inhibition (IC50 > 30 µM). Crystallographic studies confirmed the binding of 24b and the role of the fluorine atom, as well as optimal contacts of a nitrile group with the main-chain carbonyl group of H235. Furthermore, 24b showed longer half-life and favorable safety properties. All the results demonstrated that 24b has significant promise in circumventing drug resistance as an anti-HIV-1 candidate.


Assuntos
Fármacos Anti-HIV/farmacologia , Canal de Potássio ERG1/metabolismo , HIV-1/efeitos dos fármacos , Pirimidinas/farmacologia , Inibidores da Transcriptase Reversa/farmacologia , Tiofenos/farmacologia , Animais , Fármacos Anti-HIV/metabolismo , Fármacos Anti-HIV/farmacocinética , Fármacos Anti-HIV/toxicidade , Linhagem Celular , Cristalografia por Raios X , Descoberta de Drogas , Feminino , Flúor/química , Transcriptase Reversa do HIV/metabolismo , Humanos , Masculino , Camundongos , Microssomos Hepáticos/metabolismo , Estrutura Molecular , Ligação Proteica , Pirimidinas/metabolismo , Pirimidinas/farmacocinética , Pirimidinas/toxicidade , Ratos Wistar , Inibidores da Transcriptase Reversa/metabolismo , Inibidores da Transcriptase Reversa/farmacocinética , Inibidores da Transcriptase Reversa/toxicidade , Relação Estrutura-Atividade , Tiofenos/metabolismo , Tiofenos/farmacocinética , Tiofenos/toxicidade
16.
Proc Natl Acad Sci U S A ; 117(6): 2795-2804, 2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-31980532

RESUMO

The human ether-á-go-go-related gene (hERG1) channel conducts small outward K+ currents that are critical for cardiomyocyte membrane repolarization. The gain-of-function mutation N629D at the outer mouth of the selectivity filter (SF) disrupts inactivation and K+-selective transport in hERG1, leading to arrhythmogenic phenotypes associated with long-QT syndrome. Here, we combined computational electrophysiology with Markov state model analysis to investigate how SF-level gating modalities control selective cation transport in wild-type (WT) and mutant (N629D) hERG1 variants. Starting from the recently reported cryogenic electron microscopy (cryo-EM) open-state channel structure, multiple microseconds-long molecular-dynamics (MD) trajectories were generated using different cation configurations at the filter, voltages, electrolyte concentrations, and force-field parameters. Most of the K+ permeation events observed in hERG1-WT simulations occurred at microsecond timescales, influenced by the spontaneous dehydration/rehydration dynamics at the filter. The SF region displayed conductive, constricted, occluded, and dilated states, in qualitative agreement with the well-documented flickering conductance of hERG1. In line with mutagenesis studies, these gating modalities resulted from dynamic interaction networks involving residues from the SF, outer-mouth vestibule, P-helices, and S5-P segments. We found that N629D mutation significantly stabilizes the SF in a state that is permeable to both K+ and Na+, which is reminiscent of the SF in the nonselective bacterial NaK channel. Increasing the external K+ concentration induced "WT-like" SF dynamics in N629D, in qualitative agreement with the recovery of flickering currents in experiments. Overall, our findings provide an understanding of the molecular mechanisms controlling selective transport in K+ channels with a nonconventional SF sequence.


Assuntos
Canal de Potássio ERG1/química , Canal de Potássio ERG1/metabolismo , Motivos de Aminoácidos , Canal de Potássio ERG1/genética , Mutação com Ganho de Função , Humanos , Cinética , Síndrome do QT Longo/genética , Síndrome do QT Longo/metabolismo , Mutação de Sentido Incorreto , Potássio/metabolismo , Domínios Proteicos , Estrutura Secundária de Proteína
17.
Am J Pathol ; 190(1): 48-56, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31839145

RESUMO

Kv11.1 potassium channels are essential for heart repolarization. Prescription medication that blocks Kv11.1 channels lengthens the ventricular action potential and causes cardiac arrhythmias. Surprisingly little is known about the Kv11.1 channel expression and function in the lung tissue. Here we report that Kv11.1 channels were abundantly expressed in the large pulmonary arteries (PAs) of healthy lung tissues from humans and rats. Kv11.1 channel expression was increased in the lungs of humans affected by chronic obstructive pulmonary disease-associated pulmonary hypertension and in the lungs of rats with pulmonary arterial hypertension (PAH). In healthy lung tissues from humans and rats, Kv11.1 channels were confined to the large PAs. In humans with chronic obstructive pulmonary disease-associated pulmonary hypertension and in rats with PAH, Kv11.1 channels were expressed in both the large and small PAs. The increase in Kv11.1 channel expression closely followed the time-course of the development of pulmonary vascular remodeling in PAH rats. Treatment of PAH rats with dofetilide, an Kv11.1 channel blocker approved by the US Food and Drug Administration for use in the treatment of arrythmia, inhibited PAH-associated pulmonary vascular remodeling. Taken together, the findings from this study uncovered a novel role of Kv11.1 channels in lung function and their potential as new drug targets in the treatment of pulmonary hypertension. The protective effect of dofetilide raises the possibility of repurposing this antiarrhythmic drug for the treatment of patients with pulmonary hypertension.


Assuntos
Arritmias Cardíacas/prevenção & controle , Canal de Potássio ERG1/antagonistas & inibidores , Músculo Liso Vascular/efeitos dos fármacos , Fenetilaminas/farmacologia , Bloqueadores dos Canais de Potássio/farmacologia , Hipertensão Arterial Pulmonar/complicações , Sulfonamidas/farmacologia , Remodelação Vascular/efeitos dos fármacos , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/patologia , Estudos de Casos e Controles , Canal de Potássio ERG1/metabolismo , Feminino , Seguimentos , Humanos , Masculino , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Prognóstico , Hipertensão Arterial Pulmonar/metabolismo , Hipertensão Arterial Pulmonar/patologia , Ratos Sprague-Dawley
18.
J Biochem Mol Toxicol ; 34(2): e22423, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31729781

RESUMO

MicroRNAs are endogenous small noncoding RNAs that posttranscriptionally regulate the expression of target genes and play crucial roles in diverse physiopathologic processes. In the current study, we examined the microRNA (miRNA) expression profile of high-glucose-treated neonatal rat cardiomyocytes and the potential mechanisms. Differentially expressed miRNAs were analyzed by a miRNA microarray and validated by a quantitative real-time polymerase chain reaction in high-glucose-treated rat cardiomyocytes. Based on the results of our previous study and the bioinformatics prediction, we identified miR-195-5p/SGK1/Nedd4-2/hERG as the top-ranked signal pathway in diabetes cell model in vitro. In summary, our present study provides novel insights into the regulatory mechanism of miR-195-5p/SGK1/Nedd4-2/hERG in rat cardiomyocytes under high-glucose stress, which may provide a novel idea for the development of diagnostic and therapeutic strategies for diabetic cardiomyopathy in the future.


Assuntos
Cardiomiopatias Diabéticas/metabolismo , Glucose/farmacologia , MicroRNAs/genética , Miócitos Cardíacos/efeitos dos fármacos , Transcriptoma , Regiões 3' não Traduzidas/genética , Animais , Sítios de Ligação , Canal de Potássio ERG1/antagonistas & inibidores , Canal de Potássio ERG1/metabolismo , Feminino , Técnicas de Silenciamento de Genes , Células HEK293 , Humanos , Proteínas Imediatamente Precoces/antagonistas & inibidores , Proteínas Imediatamente Precoces/metabolismo , Masculino , Miócitos Cardíacos/metabolismo , Ubiquitina-Proteína Ligases Nedd4/metabolismo , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/metabolismo , Ratos , Ratos Sprague-Dawley , Transfecção
19.
Toxicol Lett ; 319: 40-48, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31706004

RESUMO

Two synthetic tryptamines, namely [3-[2-(diethylamino)ethyl]-1H-indol-4-yl] acetate (4-AcO-DET) and 3-[2-[ethyl(methyl)amino]ethyl]-1H-indol-4-ol (4-HO-MET), are abused by individuals seeking recreational hallucinogens. These new psychoactive substances (NPSs) can cause serious health problems because their adverse effects are mostly unknown. In the present study, we evaluated the cardiotoxicity of 4-AcO-DET and 4-HO-MET using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, electrocardiography (ECG), and the human ether-a-go-go-related gene (hERG) assay. In addition, we analyzed the expression level of p21 (CDC42/RAC)-activated kinase 1 (PAK1), which is known to play various roles in the cardiovascular system. In the MTT assay, 4-AcO-DET- and 4-HO-MET-treated H9c2 cells proliferated in a concentration-dependent manner. Moreover, both substances increased QT intervals (as determined using ECG) in Sprague-Dawley rats and inhibited potassium channels (as verified by the hERG assay) in Chinese hamster ovary cells. However, there was no change in PAK1 expression. Collectively, the results indicated that 4-AcO-DET and 4-HO-MET might cause adverse effects on the cardiovascular system. Further studies are required to confirm the relationship between PAK1 expression and cardiotoxicity. The findings of the present study would provide science-based evidence for scheduling the two NPSs.


Assuntos
Cardiotoxinas/toxicidade , Alucinógenos/toxicidade , Triptaminas/toxicidade , Animais , Células CHO , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Cricetulus , Canal de Potássio ERG1/metabolismo , Eletrocardiografia , Masculino , Miócitos Cardíacos/efeitos dos fármacos , Bloqueadores dos Canais de Potássio/toxicidade , Ratos , Ratos Sprague-Dawley , Quinases Ativadas por p21/biossíntese , Quinases Ativadas por p21/genética
20.
Mol Psychiatry ; 25(1): 206-229, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31570775

RESUMO

Increased expression of the 3.1 isoform of the KCNH2 potassium channel has been associated with cognitive dysfunction and with schizophrenia, yet little is known about the underlying pathophysiological mechanisms. Here, by using in vivo wireless local field potential recordings during working memory processing, in vitro brain slice whole-cell patching recordings and in vivo stereotaxic hippocampal injection of AAV-encoded expression, we identified specific and delayed disruption of hippocampal-mPFC synaptic transmission and functional connectivity associated with reductions of SERPING1, CFH, and CD74 in the KCNH2-3.1 overexpression transgenic mice. The differentially expressed genes in mice are enriched in neurons and microglia, and reduced expression of these genes dysregulates the complement cascade, which has been previously linked to synaptic plasticity. We find that knockdown of these genes in primary neuronal-microglial cocultures from KCNH2-3.1 mice impairs synapse formation, and replenishing reduced CFH gene expression rescues KCNH2-3.1-induced impaired synaptogenesis. Translating to humans, we find analogous dysfunctional interactions between hippocampus and prefrontal cortex in coupling of the fMRI blood oxygen level-dependent (BOLD) signal during working memory in healthy subjects carrying alleles associated with increased KCNH2-3.1 expression in brain. Our data uncover a previously unrecognized role of the truncated KCNH2-3.1 potassium channel in mediating complement activation, which may explain its association with altered hippocampal-prefrontal connectivity and synaptic function. These results provide a potential molecular link between increased KCNH2-3.1 expression, synapse alterations, and hippocampal-prefrontal circuit abnormalities implicated in schizophrenia.


Assuntos
Ativação do Complemento/fisiologia , Canal de Potássio ERG1/metabolismo , Memória de Curto Prazo/fisiologia , Animais , Encéfalo/metabolismo , Disfunção Cognitiva/genética , Ativação do Complemento/imunologia , Canal de Potássio ERG1/genética , Feminino , Hipocampo/metabolismo , Humanos , Imageamento por Ressonância Magnética , Masculino , Transtornos da Memória/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Plasticidade Neuronal/fisiologia , Neurônios/metabolismo , Córtex Pré-Frontal/metabolismo , Esquizofrenia/genética , Esquizofrenia/metabolismo , Transmissão Sináptica/fisiologia , Lobo Temporal/metabolismo
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