RESUMO
Previous reports indicate that IL18 is a novel candidate gene for diastolic dysfunction in sickle cell disease (SCD)-related cardiomyopathy. We hypothesize that interleukin-18 (IL-18) mediates the development of cardiomyopathy and ventricular tachycardia (VT) in SCD. Compared with control mice, a humanized mouse model of SCD exhibited increased cardiac fibrosis, prolonged duration of action potential, higher VT inducibility in vivo, higher cardiac NF-κB phosphorylation, and higher circulating IL-18 levels, as well as reduced voltage-gated potassium channel expression, which translates to reduced transient outward potassium current (Ito) in isolated cardiomyocytes. Administering IL-18 to isolated mouse hearts resulted in VT originating from the right ventricle and further reduced Ito in SCD mouse cardiomyocytes. Sustained IL-18 inhibition via IL-18-binding protein resulted in decreased cardiac fibrosis and NF-κB phosphorylation, improved diastolic function, normalized electrical remodeling, and attenuated IL-18-mediated VT in SCD mice. Patients with SCD and either myocardial fibrosis or increased QTc displayed greater IL18 gene expression in peripheral blood mononuclear cells (PBMCs), and QTc was strongly correlated with plasma IL-18 levels. PBMC-derived IL18 gene expression was increased in patients who did not survive compared with those who did. IL-18 is a mediator of sickle cell cardiomyopathy and VT in mice and a novel therapeutic target in patients at risk for sudden death.
Assuntos
Anemia Falciforme/complicações , Cardiomiopatias/etiologia , Interleucina-18/sangue , Taquicardia Ventricular/etiologia , Adulto , Anemia Falciforme/sangue , Anemia Falciforme/fisiopatologia , Animais , Arritmias Cardíacas/sangue , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/fisiopatologia , Cardiomiopatias/sangue , Cardiomiopatias/fisiopatologia , Humanos , Interleucina-18/análise , Masculino , Camundongos , Taquicardia Ventricular/sangue , Taquicardia Ventricular/fisiopatologia , Adulto JovemRESUMO
The QT interval is a recording of cardiac electrical activity. Previous genome-wide association studies identified genetic variants that modify the QT interval upstream of LITAF (lipopolysaccharide-induced tumor necrosis factor-α factor), a protein encoding a regulator of endosomal trafficking. However, it was not clear how LITAF might impact cardiac excitation. We investigated the effect of LITAF on the voltage-gated sodium channel Nav1.5, which is critical for cardiac depolarization. We show that overexpressed LITAF resulted in a significant increase in the density of Nav1.5-generated voltage-gated sodium current INa and Nav1.5 surface protein levels in rabbit cardiomyocytes and in HEK cells stably expressing Nav1.5. Proximity ligation assays showed co-localization of endogenous LITAF and Nav1.5 in cardiomyocytes, whereas co-immunoprecipitations confirmed they are in the same complex when overexpressed in HEK cells. In vitro data suggest that LITAF interacts with the ubiquitin ligase NEDD4-2, a regulator of Nav1.5. LITAF overexpression down-regulated NEDD4-2 in cardiomyocytes and HEK cells. In HEK cells, LITAF increased ubiquitination and proteasomal degradation of co-expressed NEDD4-2 and significantly blunted the negative effect of NEDD4-2 on INa We conclude that LITAF controls cardiac excitability by promoting degradation of NEDD4-2, which is essential for removal of surface Nav1.5. LITAF-knockout zebrafish showed increased variation in and a nonsignificant 15% prolongation of action potential duration. Computer simulations using a rabbit-cardiomyocyte model demonstrated that changes in Ca2+ and Na+ homeostasis are responsible for the surprisingly modest action potential duration shortening. These computational data thus corroborate findings from several genome-wide association studies that associated LITAF with QT interval variation.
Assuntos
Endossomos/metabolismo , Miócitos Cardíacos/metabolismo , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Ubiquitina-Proteína Ligases Nedd4/metabolismo , Proteínas Nucleares/metabolismo , Fatores de Transcrição/metabolismo , Ubiquitina/metabolismo , Potenciais de Ação , Animais , Estudo de Associação Genômica Ampla , Humanos , Miócitos Cardíacos/citologia , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Ubiquitina-Proteína Ligases Nedd4/genética , Proteínas Nucleares/genética , Ligação Proteica , Transporte Proteico , Coelhos , Fatores de Transcrição/genética , Ubiquitinação , Peixe-ZebraRESUMO
INTRODUCTION: Low serum magnesium (Mg) is associated with an increased incidence of atrial and ventricular arrhythmias. A richer phenotyping of arrhythmia indices, such as burden or frequency, may provide etiologic insights. OBJECTIVES: To evaluate cross-sectional associations of serum Mg with burden of atrial arrhythmias [atrial fibrillation (AF), premature atrial contractions (PAC), supraventricular tachycardia (SVT)], and ventricular arrhythmias [premature ventricular contractions (PVC), non-sustained ventricular tachycardia (NSVT)] over 2-weeks of ECG monitoring. METHODS: We included 2513 ARIC Study visit 6 (2016-2017) participants who wore the Zio XT Patch-a leadless, ambulatory ECG-monitor-for up to 2-weeks. Serum Mg was modeled categorically and continuously. AF burden was categorized as intermittent or continuous based on the percent of analyzable time spent in AF. Other arrhythmia burdens were defined by the average number of abnormal beats per day. Linear regression was used for continuous outcomes; logistic and multinomial regression were used for categorical outcomes. RESULTS: Participants were mean ± SD age 79 ± 5 years, 58% were women and 25% black. Mean serum Mg was 0.82 ± 0.08 mmol/L and 19% had hypomagnesemia (<0.75 mmol/L). Serum Mg was inversely associated with PVC burden and continuous AF. The AF association was no longer statistically significant with further adjustment for traditional lifestyle risk factors, only the association with PVC burden remained significant. There were no associations between serum Mg and other arrhythmias examined. CONCLUSIONS: In this community-based cohort of older adults, we found little evidence of independent cross-sectional associations between serum Mg and arrhythmia burden.
Assuntos
Aterosclerose , Fibrilação Atrial , Idoso , Idoso de 80 Anos ou mais , Fibrilação Atrial/epidemiologia , Estudos Transversais , Eletrocardiografia , Eletrocardiografia Ambulatorial , Feminino , Humanos , Magnésio , MasculinoRESUMO
RATIONALE: Heart failure is characterized by electrical remodeling that contributes to arrhythmic risk. The unfolded protein response (UPR) is active in heart failure and can decrease protein levels by increasing mRNA decay, accelerating protein degradation, and inhibiting protein translation. OBJECTIVE: Therefore, we investigated whether the UPR downregulated cardiac ion channels that may contribute to arrhythmogenic electrical remodeling. METHODS: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were used to study cardiac ion channels. Action potentials (APs) and ion channel currents were measured by patch clamp recording. The mRNA and protein levels of channels and the UPR effectors were determined by quantitative RT-PCR and Western blotting. Tunicamycin (TM, 50â¯ng/mL and 5⯵g/mL), GSK2606414 (GSK, 300â¯nmol/L), and 4µ8C (5⯵mol/L) were utilized to activate the UPR, inhibit protein kinase-like ER kinase (PERK) and inositol-requiring protein-1 (IRE1), respectively. RESULTS: TM-induced activation of the UPR caused significant prolongation of the AP duration (APD) and a reduction of the maximum upstroke velocity (dV/dtmax) of the AP phase 0 in both acute (20-24â¯h) and chronic treatment (6â¯days). These changes were explained by reductions in the sodium, L-type calcium, the transient outward and rapidly/slowly activating delayed rectifier potassium currents. Nav1.5, Cav1.2, Kv4.3, and KvLQT1 channels showed concomitant reductions in mRNA and protein levels under activated UPR. Inhibition of PERK or IRE1 shortened the APD and reinstated dV/dtmax. The PERK branch regulated Nav1.5, Kv4.3, hERG, and KvLQT1. The IRE1 branch regulated Nav1.5, hERG, KvLQT1, and Cav1.2. CONCLUSIONS: Activated UPR downregulates all major cardiac ion currents and results in electrical remodeling in hiPSC-CMs. Both PERK and IRE1 branches downregulate Nav1.5, hERG, and KvLQT1. The PERK branch specifically downregulates Kv4.3, while the IRE1 branch downregulates Cav1.2. Therefore, the UPR contributed to electrical remodeling, and targeting the UPR might be anti-arrhythmic.
Assuntos
Regulação para Baixo , Células-Tronco Pluripotentes Induzidas/citologia , Canais Iônicos/metabolismo , Miócitos Cardíacos/metabolismo , Resposta a Proteínas não Dobradas , Potenciais de Ação/efeitos dos fármacos , Adenina/análogos & derivados , Adenina/farmacologia , Regulação para Baixo/efeitos dos fármacos , Endorribonucleases/metabolismo , Humanos , Indóis/farmacologia , Ativação do Canal Iônico/efeitos dos fármacos , Isoproterenol/farmacologia , Miócitos Cardíacos/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Tunicamicina/farmacologia , Resposta a Proteínas não Dobradas/efeitos dos fármacos , Remodelação Ventricular/efeitos dos fármacos , eIF-2 Quinase/metabolismoRESUMO
Right ventricular (RV) dysfunction is associated with numerous smoking-related illnesses, including chronic obstructive pulmonary disease (COPD), in which it is present even in the absence of pulmonary hypertension. It is unknown whether exposure to cigarette smoke (CS) has direct effects on RV function and cardiac fibroblast (CF) proliferation or collagen synthesis. In this study, we evaluated cardiac function and fibrosis in mice exposed to CS and determined mechanisms of smoke-induced changes in CF signaling and fibrosis. AKR mice were exposed to CS for 6 wk followed by echocardiography and evaluation of cardiac hypertrophy, collagen content, and pulmonary muscularization. Proliferation and collagen content were evaluated in primary isolated rat CFs exposed to CS extract (CSE) or nicotine. Markers of cell proliferation, fibrosis, and proliferative signaling were determined by immunoblot or Sircol collagen assay. Mice exposed to CS had significantly decreased RV function, as determined by tricuspid annular plane systolic excursion. There were no changes in left ventricular parameters. RV collagen content was significantly elevated, but there was no change in RV hypertrophy or pulmonary vascular muscularization. CSE directly increased CF proliferation and collagen content in CF. Nicotine alone reproduced these effects. CSE and nicotine-induced fibroblast proliferation and collagen content were mediated through α7 nicotinic acetylcholine receptors and were dependent on PKC-α, PKC-δ, and reduced p38-MAPK phosphorylation. CS and nicotine have direct effects on CFs to induce proliferation and fibrosis, which may negatively affect right heart function.
Assuntos
Fibroblastos/metabolismo , Fibroblastos/patologia , Ventrículos do Coração/patologia , Miocárdio/patologia , Fumar/efeitos adversos , Receptor Nicotínico de Acetilcolina alfa7/metabolismo , Animais , Proliferação de Células/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Fibroblastos/efeitos dos fármacos , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/fisiopatologia , Hemodinâmica/efeitos dos fármacos , Hipertrofia Ventricular Direita/complicações , Hipertrofia Ventricular Direita/diagnóstico por imagem , Hipertrofia Ventricular Direita/patologia , Hipertrofia Ventricular Direita/fisiopatologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Masculino , Camundongos Endogâmicos AKR , Nicotina/farmacologia , Fosforilação/efeitos dos fármacos , Proteína Quinase C-alfa/metabolismo , Proteína Quinase C-delta/metabolismo , Ratos Sprague-Dawley , Remodelação Vascular/efeitos dos fármacos , Disfunção Ventricular Direita/complicações , Disfunção Ventricular Direita/diagnóstico por imagem , Disfunção Ventricular Direita/patologia , Disfunção Ventricular Direita/fisiopatologia , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Ventricular arrhythmia is the leading cause of sudden cardiac death (SCD). Deranged cardiac metabolism and abnormal redox state during cardiac diseases foment arrhythmogenic substrates through direct or indirect modulation of cardiac ion channel/transporter function. This review presents current evidence on the mechanisms linking metabolic derangement and excessive oxidative stress to ion channel/transporter dysfunction that predisposes to ventricular arrhythmias and SCD. Because conventional antiarrhythmic agents aiming at ion channels have proven challenging to use, targeting arrhythmogenic metabolic changes and redox imbalance may provide novel therapeutics to treat or prevent life-threatening arrhythmias and SCD.
Assuntos
Morte Súbita Cardíaca/etiologia , Cardiopatias/metabolismo , Miocárdio/metabolismo , Arritmias Cardíacas/tratamento farmacológico , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/metabolismo , Sinalização do Cálcio , Fármacos Cardiovasculares/farmacologia , Fármacos Cardiovasculares/uso terapêutico , Morte Súbita Cardíaca/prevenção & controle , Junções Comunicantes/fisiologia , Sistema de Condução Cardíaco/fisiopatologia , Homeostase , Humanos , Ativação do Canal Iônico/efeitos dos fármacos , Ativação do Canal Iônico/fisiologia , Canais Iônicos/efeitos dos fármacos , Canais Iônicos/fisiologia , Potenciais da Membrana , Doenças Metabólicas/complicações , Doenças Metabólicas/fisiopatologia , Mitocôndrias Cardíacas/metabolismo , Oxirredução , Estresse Oxidativo , Potássio/fisiologia , Espécies Reativas de Oxigênio , Sódio/fisiologiaRESUMO
AIMS: Heart failure patients are at increased risk of ventricular arrhythmias and all-cause mortality. However, existing clinical and serum markers only modestly predict these adverse events. We sought to use metabolic profiling to identify novel biomarkers in two independent prospective cohorts of patients with implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden cardiac death (SCD). METHODS AND RESULTS: Baseline serum was quantitatively profiled for 42 known biologically relevant amine-based metabolites among 402 patients from the Prospective Observational Study of Implantable Cardioverter-Defibrillators (PROSE-ICD) Study (derivation group) and 240 patients from the Genetic Risk Assessment of Defibrillator Events (GRADE) Study (validation group) for ventricular arrhythmia-induced ICD shocks and all-cause mortality. Three amines, N-methyl-l-histidine, symmetric dimethylarginine (SDMA), and l-kynurenine, were derived and validated to be associated with all-cause mortality. The hazard ratios of mortality in PROSE-ICD and GRADE were 1.48 (95% confidence interval 1.14-1.92) and 1.67 (1.22-2.27) for N-methyl-l-histidine, 1.49 (1.17-1.91) and 1.77 (1.27-2.45) for SDMA, 1.31 (1.06-1.63) and 1.73 (1.32-2.27) for l-kynurenine, respectively. l-Histidine, SDMA, and l-kynurenine were associated with ventricular arrhythmia-induced ICD shocks in PROSE-ICD, but they did not reach statistical significance in the GRADE cohort. CONCLUSION: Utilizing metabolic profiling in two independent prospective cohorts of patients undergoing ICD implantation for primary prevention of SCD, we identified several novel amine markers that were associated with appropriate shock and mortality. These findings shed insight into the potential biologic pathways leading to adverse events in ICD patients. Further studies are needed to confirm the prognostic value of these findings.
Assuntos
Aminas/sangue , Morte Súbita Cardíaca/prevenção & controle , Desfibriladores Implantáveis , Cardioversão Elétrica/instrumentação , Insuficiência Cardíaca/terapia , Prevenção Primária/métodos , Idoso , Arginina/análogos & derivados , Arginina/sangue , Biomarcadores/sangue , Morte Súbita Cardíaca/etiologia , Cardioversão Elétrica/efeitos adversos , Cardioversão Elétrica/mortalidade , Feminino , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/mortalidade , Humanos , Cinurenina/sangue , Masculino , Metabolômica , Metilistidinas/sangue , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Prospectivos , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Estados UnidosRESUMO
Despite the growing number of patients affected, the understanding of diastolic dysfunction and heart failure with preserved ejection fraction (HFpEF) is still poor. Clinical trials, largely based on successful treatments for systolic heart failure, have been disappointing, suggesting that HFpEF has a different pathology to that of systolic dysfunction. In this review, general concepts, epidemiology, diagnosis, and treatment of diastolic dysfunction are summarized, with an emphasis on new experiments suggesting that oxidative stress plays a crucial role in the pathogenesis of at least some forms of the disease. This observation has lead to potential new diagnostics and therapeutics for diastolic dysfunction and heart failure caused by diastolic dysfunction.
Assuntos
Diástole , Insuficiência Cardíaca , Estresse Oxidativo , Volume Sistólico , Animais , Ensaios Clínicos como Assunto , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/terapia , HumanosRESUMO
The unfolded protein response (UPR) has been extensively investigated in neurological diseases and diabetes, while its function in heart disease is less well understood. Activated UPR participates in multiple cardiac conditions and can either protect or impair heart function. Recently, the UPR has been found to play a role in arrhythmogenesis during human heart failure by affecting cardiac ion channels expression, and blocking UPR has an antiarrhythmic effect. This review will discuss the rationale for and challenges to targeting UPR in heart disease for treatment of arrhythmias.
Assuntos
Arritmias Cardíacas/metabolismo , Cardiopatias/metabolismo , Resposta a Proteínas não Dobradas , Animais , Arritmias Cardíacas/tratamento farmacológico , Arritmias Cardíacas/genética , Arritmias Cardíacas/patologia , Chaperona BiP do Retículo Endoplasmático , Cardiopatias/tratamento farmacológico , Cardiopatias/genética , Cardiopatias/patologia , Humanos , Terapia de Alvo Molecular , Resposta a Proteínas não Dobradas/efeitos dos fármacosRESUMO
RATIONALE: Previously, we demonstrated that a deoxycorticosterone acetate (DOCA)-salt hypertensive mouse model produces cardiac oxidative stress and diastolic dysfunction with preserved systolic function. Oxidative stress has been shown to increase late inward sodium current (I(Na)), reducing the net cytosolic Ca(2+) efflux. OBJECTIVE: Oxidative stress in the DOCA-salt model may increase late I(Na), resulting in diastolic dysfunction amenable to treatment with ranolazine. METHODS AND RESULTS: Echocardiography detected evidence of diastolic dysfunction in hypertensive mice that improved after treatment with ranolazine (E/E':sham, 31.9 ± 2.8, sham+ranolazine, 30.2 ± 1.9, DOCA-salt, 41.8 ± 2.6, and DOCA-salt+ranolazine, 31.9 ± 2.6; P=0.018). The end-diastolic pressure-volume relationship slope was elevated in DOCA-salt mice, improving to sham levels with treatment (sham, 0.16 ± 0.01 versus sham+ranolazine, 0.18 ± 0.01 versus DOCA-salt, 0.23 ± 0.2 versus DOCA-salt+ranolazine, 0.17 ± 0.0 1 mm Hg/L; P<0.005). DOCA-salt myocytes demonstrated impaired relaxation, τ, improving with ranolazine (DOCA-salt, 0.18 ± 0.02, DOCA-salt+ranolazine, 0.13 ± 0.01, sham, 0.11 ± 0.01, sham+ranolazine, 0.09 ± 0.02 seconds; P=0.0004). Neither late I(Na) nor the Ca(2+) transients were different from sham myocytes. Detergent extracted fiber bundles from DOCA-salt hearts demonstrated increased myofilament response to Ca(2+) with glutathionylation of myosin binding protein C. Treatment with ranolazine ameliorated the Ca(2+) response and cross-bridge kinetics. CONCLUSIONS: Diastolic dysfunction could be reversed by ranolazine, probably resulting from a direct effect on myofilaments, indicating that cardiac oxidative stress may mediate diastolic dysfunction through altering the contractile apparatus.
Assuntos
Acetanilidas/farmacologia , Cálcio/metabolismo , Diástole/efeitos dos fármacos , Insuficiência Cardíaca Diastólica/tratamento farmacológico , Miócitos Cardíacos/efeitos dos fármacos , Miofibrilas/efeitos dos fármacos , Piperazinas/farmacologia , Acetanilidas/sangue , Animais , Desoxicorticosterona/toxicidade , Diástole/fisiologia , Modelos Animais de Doenças , Inibidores Enzimáticos/sangue , Inibidores Enzimáticos/farmacologia , Insuficiência Cardíaca Diastólica/induzido quimicamente , Insuficiência Cardíaca Diastólica/fisiopatologia , Camundongos , Mineralocorticoides/toxicidade , Contração Miocárdica/efeitos dos fármacos , Contração Miocárdica/fisiologia , Miócitos Cardíacos/fisiologia , Miofibrilas/metabolismo , Estresse Oxidativo/fisiologia , Piperazinas/sangue , Ranolazina , Sódio/metabolismo , Disfunção Ventricular Esquerda/induzido quimicamente , Disfunção Ventricular Esquerda/tratamento farmacológico , Disfunção Ventricular Esquerda/fisiopatologiaRESUMO
Diabetes mellitus (DM) is an independent risk factor for atrial fibrillation (AF). The mechanisms underlying DM-associated AF are unclear. AF and DM are both related to inflammation. We investigated whether DM-associated inflammation contributed to AF risk. Mice were fed with high-fat diet to induce type II DM and were subjected to IL-1ß antibodies, macrophage depletion by clodronate liposomes, a mitochondrial antioxidant (mitoTEMPO), or a cardiac ryanodine receptor 2 (RyR2) stabilizer (S107). All tests were performed at 36-38 weeks of age. DM mice presented with increased AF inducibility, enhanced mitochondrial reactive oxygen species (mitoROS) generation, and activated innate immunity in the atria, as evidenced by enhanced monocyte chemoattractant protein-1 (MCP-1) expression, macrophage infiltration, and IL-1ß levels. Signs of aberrant RyR2 Ca2+ leak were observed in the atria of DM mice. IL-1ß neutralization, macrophage depletion, and exposure to mitoTEMPO and S107 significantly ameliorated the AF vulnerability in DM mice. Atrial overexpression of MCP-1 increased AF occurrence in normal mice through the same mechanistic signaling cascade as observed in DM mice. In conclusion, macrophage-mediated IL-1ß contributed to DM-associated AF risk through mitoROS modulation of RyR2 Ca2+ leak.
Assuntos
Fibrilação Atrial , Diabetes Mellitus Experimental , Interleucina-1beta , Macrófagos , Animais , Fibrilação Atrial/metabolismo , Fibrilação Atrial/etiologia , Fibrilação Atrial/imunologia , Camundongos , Interleucina-1beta/metabolismo , Macrófagos/metabolismo , Macrófagos/imunologia , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/imunologia , Masculino , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/imunologia , Quimiocina CCL2/metabolismo , Átrios do Coração/metabolismo , Átrios do Coração/patologia , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Camundongos Endogâmicos C57BL , Dieta Hiperlipídica/efeitos adversos , Inflamação/metabolismoRESUMO
Successful heart development depends on the careful orchestration of a network of transcription factors and signaling pathways. In recent years, in vitro cardiac differentiation using human pluripotent stem cells (hPSCs) has been used to uncover the intricate gene-network regulation involved in the proper formation and function of the human heart. Here, we searched for uncharacterized cardiac-development genes by combining a temporal evaluation of human cardiac specification in vitro with an analysis of gene expression in fetal and adult heart tissue. We discovered that CARDEL (CARdiac DEvelopment Long non-coding RNA; LINC00890; SERTM2) expression coincides with the commitment to the cardiac lineage. CARDEL knockout hPSCs differentiated poorly into cardiac cells, and hPSC-derived cardiomyocytes showed faster beating rates after controlled overexpression of CARDEL during differentiation. Altogether, we provide physiological and molecular evidence that CARDEL expression contributes to sculpting the cardiac program during cell-fate commitment.
Assuntos
Diferenciação Celular , Coração , Homeostase , Miócitos Cardíacos , RNA Longo não Codificante , Humanos , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Diferenciação Celular/genética , Coração/embriologia , Coração/fisiologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/citologia , Regulação da Expressão Gênica no Desenvolvimento , Células-Tronco Pluripotentes/metabolismo , Células-Tronco Pluripotentes/citologia , Linhagem da Célula/genética , Organogênese/genéticaRESUMO
Cardiomyopathy is associated with cardiac Na(+) channel downregulation that may contribute to arrhythmias. Previously, we have shown that elevated intracellular NADH causes a decrease in cardiac Na(+) current (I(Na)) signaled by an increase in mitochondrial reactive oxygen species (ROS). In this study, we tested whether the NADH-mitochondria ROS pathway was involved in the reduction of I(Na) in a nonischemic cardiomyopathic model and correlated the findings with myopathic human hearts. Nonischemic cardiomyopathy was induced in C57BL/6 mice by hypertension after unilateral nephrectomy, deoxycorticosterone acetate (DOCA) pellet implantation, and salt water substitution. Sham operated mice were used as controls. After six weeks, heart tissue and ventricular myocytes isolated from mice were utilized for whole cell patch clamp recording, NADH/NAD(+) level measurements, and mitochondrial ROS monitoring with confocal microscopy. Human explanted hearts were studied using optical mapping. Compared to the sham mice, the arterial blood pressure was higher, the left ventricular volume was significantly enlarged (104.7±3.9 vs. 87.9±6.1 µL, P<0.05), and the ejection fraction was reduced (37.1±1.8% vs. 49.4±3.7%, P<0.05) in DOCA mice. Both the whole cell and cytosolic NADH level were increased (279±70% and 123±2% of sham, respectively, P<0.01), I(Na) was decreased (60±10% of sham, P<0.01), and mitochondrial ROS overproduction was observed (2.9±0.3-fold of sham, P<0.01) in heart tissue and myocytes of myopathic mice vs. sham. Treatment of myocytes with NAD(+) (500 µM), mitoTEMPO (10 µM), chelerythrine (50 µM), or forskolin (5 µM) restored I(Na) back to the level of sham. Injection of NAD(+) (100mg/kg) or mitoTEMPO (0.7 mg/kg) twice (at 24h and 1h before myocyte isolation) to animals also restored I(Na). All treatments simultaneously reduced mitochondrial ROS levels to that of controls. CD38 was found to transduce the extracellular NAD(+) signal. Correlating with the mouse model, failing human hearts showed a reduction in conduction velocity that improved with NAD(+). Nonischemic cardiomyopathy was associated with elevated NADH level, PKC activation, mitochondrial ROS overproduction, and a concomitant decrease in I(Na). Reducing mitochondrial ROS by application of NAD(+), mitoTEMPO, PKC inhibitors, or PKA activators, restored I(Na). NAD(+) improved conduction velocity in human myopathic hearts.
Assuntos
Cardiomiopatias/metabolismo , Mitocôndrias Cardíacas/fisiologia , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , ADP-Ribosil Ciclase 1/metabolismo , Potenciais de Ação/efeitos dos fármacos , Animais , Benzofenantridinas/farmacologia , Colforsina/farmacologia , Regulação para Baixo , Sistema de Condução Cardíaco/efeitos dos fármacos , Sistema de Condução Cardíaco/fisiopatologia , Humanos , Técnicas In Vitro , Glicoproteínas de Membrana/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/fisiologia , NAD/metabolismo , NAD/farmacologia , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Compostos Organofosforados/farmacologia , Estresse Oxidativo , Técnicas de Patch-Clamp , Piperidinas/farmacologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
Despite the increasing prevalence of heart failure with preserved left ventricular function, there are no specific treatments, partially because the mechanism of impaired relaxation is incompletely understood. Evidence indicates that cardiac relaxation may depend on nitric oxide (NO), generated by NO synthase (NOS) requiring the co-factor tetrahydrobiopterin (BH(4)). Recently, we reported that hypertension-induced diastolic dysfunction was accompanied by cardiac BH(4) depletion, NOS uncoupling, a depression in myofilament cross-bridge kinetics, and S-glutathionylation of myosin binding protein C (MyBP-C). We hypothesized that the mechanism by which BH(4) ameliorates diastolic dysfunction is by preventing glutathionylation of MyBP-C and thus reversing changes of myofilament properties that occur during diastolic dysfunction. We used the deoxycorticosterone acetate (DOCA)-salt mouse model, which demonstrates mild hypertension, myocardial oxidative stress, and diastolic dysfunction. Mice were divided into two groups that received control diet and two groups that received BH(4) supplement for 7days after developing diastolic dysfunction at post-operative day 11. Mice were assessed by echocardiography. Left ventricular papillary detergent-extracted fiber bundles were isolated for simultaneous determination of force and ATPase activity. Sarcomeric protein glutathionylation was assessed by immunoblotting. DOCA-salt mice exhibited diastolic dysfunction that was reversed after BH(4) treatment. Diastolic sarcomere length (DOCA-salt 1.70±0.01 vs. DOCA-salt+BH(4) 1.77±0.01µm, P<0.001) and relengthening (relaxation constant, τ, DOCA-salt 0.28±0.02 vs. DOCA-salt+BH(4) 0.08±0.01, P<0.001) were also restored to control by BH(4) treatment. pCa(50) for tension increased in DOCA-salt compared to sham but reverted to sham levels after BH(4) treatment. Maximum ATPase rate and tension cost (ΔATPase/ΔTension) decreased in DOCA-salt compared to sham, but increased after BH(4) treatment. Cardiac MyBP-C glutathionylation increased in DOCA-salt compared to sham, but decreased with BH(4) treatment. MyBP-C glutathionylation correlated with the presence of diastolic dysfunction. Our results suggest that by depressing S-glutathionylation of MyBP-C, BH(4) ameliorates diastolic dysfunction by reversing a decrease in cross-bridge turnover kinetics. These data provide evidence for modulation of cardiac relaxation by post-translational modification of myofilament proteins.
Assuntos
Biopterinas/análogos & derivados , Fármacos Cardiovasculares/administração & dosagem , Insuficiência Cardíaca Diastólica/tratamento farmacológico , Miofibrilas/fisiologia , Adenosina Trifosfatases/metabolismo , Administração Oral , Animais , Biopterinas/administração & dosagem , Proteínas de Transporte/metabolismo , Células Cultivadas , Desoxicorticosterona/farmacologia , Diástole/efeitos dos fármacos , Suplementos Nutricionais , Glutationa/metabolismo , Insuficiência Cardíaca Diastólica/diagnóstico por imagem , Insuficiência Cardíaca Diastólica/fisiopatologia , Camundongos , Miofibrilas/efeitos dos fármacos , Miofibrilas/enzimologia , Estresse Oxidativo , Processamento de Proteína Pós-Traducional , Volume Sistólico/efeitos dos fármacos , UltrassonografiaRESUMO
As the second most abundant intracellular divalent cation, magnesium (Mg2+) is essential for cell functions, such as ATP production, protein/DNA synthesis, protein activity, and mitochondrial function. Mg2+ plays a critical role in heart rhythm, muscle contraction, and blood pressure. A significant decline in Mg2+ intake has been reported in developed countries because of the increased consumption of processed food and filtered/deionized water, which can lead to hypomagnesemia (HypoMg). HypoMg is commonly observed in cardiovascular diseases, such as heart failure, hypertension, arrhythmias, and diabetic cardiomyopathy, and HypoMg is a predictor for cardiovascular and all-cause mortality. On the other hand, Mg2+ supplementation has shown significant therapeutic effects in cardiovascular diseases. Some of the effects of HypoMg have been ascribed to changes in Mg2+ participation in enzyme activity, ATP stabilization, enzyme kinetics, and alterations in Ca2+, Na+, and other cations. In this manuscript, we discuss new insights into the pathogenic mechanisms of HypoMg that surpass previously described effects. HypoMg causes mitochondrial dysfunction, oxidative stress, and inflammation. Many of these effects can be attributed to the HypoMg-induced upregulation of a Mg2+ transporter transient receptor potential melastatin 7 channel (TRMP7) that is also a kinase. An increase in kinase signaling mediated by HypoMg-induced TRPM7 transcriptional upregulation, independently of any change in Mg2+ transport function, likely seems responsible for many of the effects of HypoMg. Therefore, Mg2+ supplementation and TRPM7 kinase inhibition may work to treat the sequelae of HypoMg by preventing increased TRPM7 kinase activity rather than just altering ion homeostasis. Since many diseases are characterized by oxidative stress or inflammation, Mg2+ supplementation and TRPM7 kinase inhibition may have wider implications for other diseases by acting to reduce oxidative stress and inflammation.
Assuntos
Doenças Cardiovasculares , Canais de Cátion TRPM , Humanos , Magnésio , Inflamação , Homeostase , Trifosfato de Adenosina , Proteínas Serina-Treonina QuinasesRESUMO
BACKGROUND: MicroRNA miR-448 mediates some of the effects of ischemia on arrhythmic risk. Potassium voltage-gated channel subfamily A member 4 (KCNA4) encodes a Kv1.4 current that opens in response to membrane depolarization and is essential for regulating the action potential duration in heart. KCNA4 has a miR-448 binding site. OBJECTIVE: We investigated whether miR-448 was involved in the regulation of KCNA4 messenger RNA expression in ischemia. METHODS: Quantitative real-time reverse-transcriptase polymerase chain reaction was used to investigate the expression of KCNA4 and miR-448. Pull-down assays were used to examine the interaction between miR-448 and KCNA4. miR-448 decoy and binding site mutation were used to examine the specificity of the effect for KCNA4. RESULTS: The expression of KCNA4 is diminished in ischemia and human heart failure tissues with ventricular tachycardia. Previously, we have shown that miR-448 is upregulated in ischemia and inhibition can prevent arrhythmic risk after myocardial infarction. The 3'-untranslated region of KCNA4 has a conserved miR-448 binding site. miR-448 bound to this site directly and reduced KCNA4 expression and the transient outward potassium current. Inhibition of miR-448 restored KCNA4. CONCLUSION: These findings showed a link between Kv1.4 downregulation and miR-448-mediated upregulation in ischemia, suggesting a new mechanism for the antiarrhythmic effect of miR-448 inhibition.
Assuntos
Insuficiência Cardíaca , Canal de Potássio Kv1.4 , MicroRNAs , Humanos , Regulação para Baixo , Insuficiência Cardíaca/genética , MicroRNAs/genética , Infarto do Miocárdio/metabolismo , Potássio/metabolismo , Canal de Potássio Kv1.4/metabolismo , Isquemia/metabolismoRESUMO
Hypomagnesemia (HypoMg) can cause seizures and death, but the mechanism is unknown. Transient receptor potential cation channel subfamily M 7 (TRPM7) is a Mg transporter with both channel and kinase function. In this study, we focused on the kinase role of TRPM7 in HypoMg-induced seizures and death. Wild type C57BL/6J mice and transgenic mice with a global homozygous mutation in the TRPM7 kinase domain (TRPM7K1646R, with no kinase function) were fed with control diet or a HypoMg diet. After 6 weeks of HypoMg diet, mice had significantly decreased serum Mg, elevated brain TRPM7, and a significant rate of death, with females being most susceptible. Deaths were immediately preceded by seizure events. TRPM7K1646R mice showed resistance to seizure-induced death. HypoMg-induced brain inflammation and oxidative stress were suppressed by TRPM7K1646R. Compared to their male counterparts, HypoMg female mice had higher levels of inflammation and oxidative stress in the hippocampus. We concluded that TRPM7 kinase function contributes seizure-induced deaths in HypoMg mice and that inhibiting the kinase reduced inflammation and oxidative stress.
Assuntos
Canais de Cátion TRPM , Camundongos , Masculino , Feminino , Animais , Canais de Cátion TRPM/genética , Camundongos Endogâmicos C57BL , Magnésio/metabolismo , Camundongos Transgênicos , ConvulsõesRESUMO
Diabetes mellitus (DM) is a main risk factor for diastolic dysfunction (DD) and heart failure with preserved ejection fraction. High-fat diet (HFD) mice presented with diabetes mellitus, DD, higher cardiac interleukin (IL)-1ß levels, and proinflammatory cardiac macrophage accumulation. DD was significantly ameliorated by suppressing IL-1ß signaling or depleting macrophages. Mice with macrophages unable to adopt a proinflammatory phenotype were low in cardiac IL-1ß levels and were resistant to HFD-induced DD. IL-1ß enhanced mitochondrial reactive oxygen species (mitoROS) in cardiomyocytes, and scavenging mitoROS improved HFD-induced DD. In conclusion, macrophage-mediated inflammation contributed to HFD-associated DD through IL-1ß and mitoROS production.
RESUMO
Automaticity involves Ca2+ handling at the cell membrane and sarcoplasmic reticulum (SR). Abnormal or acquired automaticity is thought to initiate ventricular arrhythmias associated with myocardial ischemia. Ca2+ flux from mitochondria can influence automaticity, and lysosomes also release Ca2+. Therefore, we tested whether lysosomal Ca2+ flux could influence automaticity. We studied ventricular human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), hiPSC 3D engineered heart tissues (EHTs), and ventricular cardiomyocytes isolated from infarcted mice. Preventing lysosomal Ca2+ cycling reduced automaticity in hiPSC-CMs. Consistent with a lysosomal role in automaticity, activating the transient receptor potential mucolipin channel (TRPML1) enhanced automaticity, and two channel antagonists reduced spontaneous activity. Activation or inhibition of lysosomal transcription factor EB (TFEB) increased or decreased total lysosomes and automaticity, respectively. In adult ischemic cardiomyocytes and hiPSC 3D EHTs, reducing lysosomal Ca2+ release also inhibited automaticity. Finally, TRPML1 was up-regulated in cardiomyopathic patients with ventricular tachycardia (VT) compared with those without VT. In summary, lysosomal Ca2+ handling modulates abnormal automaticity, and reducing lysosomal Ca2+ release may be a clinical strategy for preventing ventricular arrhythmias.
RESUMO
BACKGROUND: Emerging evidence suggests that atrial myopathy may be the underlying pathophysiology that explains adverse cardiovascular outcomes in heart failure (HF) and atrial fibrillation. Lower left atrial (LA) function (strain) is a key biomarker of atrial myopathy, but murine LA strain has not been described, thus limiting translational investigation. Therefore, the objective of this study was to characterize LA function by speckle-tracking echocardiography in mouse models of atrial myopathy. METHODS: We used 3 models of atrial myopathy in wild-type male and female C57Bl6/J mice: (1) aged 16 to 17 months, (2) Ang II (angiotensin II) infusion, and (3) high-fat diet+Nω-nitro-L-arginine methyl ester (HF with preserved ejection fraction, HFpEF). LA reservoir, conduit, and contractile strain were measured using speckle-tracking echocardiography from a modified parasternal long-axis window. Left ventricular systolic and diastolic function, and global longitudinal strain were also measured. Transesophageal rapid atrial pacing was used to induce atrial fibrillation. RESULTS: LA reservoir, conduit, and contractile strain were significantly reduced in aged, Ang II and HFpEF mice compared with young controls. There were no sex-based interactions. Left ventricular diastolic function and global longitudinal strain were lower in aged, Ang II and HFpEF, but left ventricular ejection fraction was unchanged. Atrial fibrillation inducibility was low in young mice (5%), moderately higher in aged mice (20%), and high in Ang II (75%) and HFpEF (83%) mice. CONCLUSIONS: Using speckle-tracking echocardiography, we observed reduced LA function in established mouse models of atrial myopathy with concurrent atrial fibrillation inducibility, thus providing the field with a timely and clinically relevant platform for understanding the pathophysiology and discovery of novel treatment targets for atrial myopathy.