Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 46
Filtrar
Más filtros

Bases de datos
Tipo del documento
Intervalo de año de publicación
1.
J Mol Cell Cardiol ; 129: 314-325, 2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30898664

RESUMEN

Statins, in addition to their cholesterol lowering effects, can prevent isoprenylation of Rab GTPase proteins, a key protein family for the regulation of protein trafficking. Rab-GTPases have been shown to be involved in the control of membrane expression level of ion channels, including one of the major cardiac repolarizing channels, IKs. Decreased IKs function has been observed in a number of disease states and associated with increased propensity for arrhythmias, but the mechanism underlying IKs decrease remains elusive. Ca2+-dependent PKC isoforms (cPKC) are chronically activated in variety of human diseases and have been suggested to acutely regulate IKs function. We hypothesize that chronic cPKC stimulation leads to Rab-mediated decrease in IKs membrane expression, and that can be prevented by statins. In this study we show that chronic cPKC stimulation caused a dramatic Rab5 GTPase-dependent decrease in plasma membrane localization of the IKs pore forming subunit KCNQ1, reducing IKs function. Our data indicates fluvastatin inhibition of Rab5 restores channel localization and function after cPKC-mediated channel internalization. Our results indicate a novel statin anti-arrhythmic effect that would be expected to inhibit pathological electrical remodeling in a number of disease states associated with high cPKC activation. Because Rab-GTPases are important regulators of membrane trafficking they may underlie other statin pleiotropic effects.


Asunto(s)
Calcio/metabolismo , Endocitosis , Fluvastatina/farmacología , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/metabolismo , Proteína Quinasa C/metabolismo , Proteínas de Unión al GTP rab5/metabolismo , Animales , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Dinaminas/metabolismo , Endocitosis/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Femenino , Células HEK293 , Humanos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Modelos Biológicos , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Ratas
2.
Am J Physiol Cell Physiol ; 316(5): C583-C604, 2019 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-30758993

RESUMEN

Mitochondrial fragmentation frequently occurs in chronic pathological conditions as seen in various human diseases. In fact, abnormal mitochondrial morphology and mitochondrial dysfunction are hallmarks of heart failure (HF) in both human patients and HF animal models. A link between mitochondrial fragmentation and cardiac pathologies has been widely proposed, but the physiological relevance of mitochondrial fission and fusion in the heart is still unclear. Recent studies have increasingly shown that posttranslational modifications (PTMs) of fission and fusion proteins are capable of directly modulating the stability, localization, and/or activity of these proteins. These PTMs include phosphorylation, acetylation, ubiquitination, conjugation of small ubiquitin-like modifier proteins, O-linked-N-acetyl-glucosamine glycosylation, and proteolysis. Thus, understanding the PTMs of fission and fusion proteins may allow us to understand the complexities that determine the balance of mitochondrial fission and fusion as well as mitochondrial function in various cell types and organs including cardiomyocytes and the heart. In this review, we summarize present knowledge regarding the function and regulation of mitochondrial fission and fusion in cardiomyocytes, specifically focusing on the PTMs of each mitochondrial fission/fusion protein. We also discuss the molecular mechanisms underlying abnormal mitochondrial morphology in HF and their contributions to the development of cardiac diseases, highlighting the crucial roles of PTMs of mitochondrial fission and fusion proteins. Finally, we discuss the future potential of manipulating PTMs of fission and fusion proteins as a therapeutic strategy for preventing and/or treating HF.


Asunto(s)
Cardiopatías/metabolismo , Dinámicas Mitocondriales/fisiología , Proteínas Mitocondriales/metabolismo , Miocitos Cardíacos/metabolismo , Procesamiento Proteico-Postraduccional/fisiología , Animales , Cardiopatías/genética , Humanos , Proteínas Mitocondriales/genética
3.
Arch Biochem Biophys ; 663: 276-287, 2019 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-30684463

RESUMEN

Recent discoveries of the molecular identity of mitochondrial Ca2+ influx/efflux mechanisms have placed mitochondrial Ca2+ transport at center stage in views of cellular regulation in various cell-types/tissues. Indeed, mitochondria in cardiac muscles also possess the molecular components for efficient uptake and extraction of Ca2+. Over the last several years, multiple groups have taken advantage of newly available molecular information about these proteins and applied genetic tools to delineate the precise mechanisms for mitochondrial Ca2+ handling in cardiomyocytes and its contribution to excitation-contraction/metabolism coupling in the heart. Though mitochondrial Ca2+ has been proposed as one of the most crucial secondary messengers in controlling a cardiomyocyte's life and death, the detailed mechanisms of how mitochondrial Ca2+ regulates physiological mitochondrial and cellular functions in cardiac muscles, and how disorders of this mechanism lead to cardiac diseases remain unclear. In this review, we summarize the current controversies and discrepancies regarding cardiac mitochondrial Ca2+ signaling that remain in the field to provide a platform for future discussions and experiments to help close this gap.


Asunto(s)
Calcio/metabolismo , Homeostasis , Mitocondrias Cardíacas/metabolismo , Miocardio/metabolismo , Adenosina Trifosfato/biosíntesis , Señalización del Calcio , Humanos , Transporte Iónico , Miocitos Cardíacos/metabolismo
4.
Am J Respir Cell Mol Biol ; 58(5): 658-667, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29100477

RESUMEN

Hyperproliferative endothelial cells (ECs) play an important role in the pathogenesis of pulmonary arterial hypertension (PAH). Anoctamin (Ano)-1, a calcium-activated chloride channel, can regulate cell proliferation and cell cycle in multiple cell types. However, the expression and function of Ano1 in the pulmonary endothelium is unknown. We examined whether Ano1 was expressed in pulmonary ECs and if altering Ano1 activity would affect EC survival. Expression and localization of Ano1 in rat lung microvascular ECs (RLMVECs) was assessed using immunoblot, immunofluorescence, and subcellular fractionation. Cell counts, flow cytometry, and caspase-3 activity were used to assess changes in cell number and apoptosis in response to the small molecule Ano1 activator, Eact. Changes in mitochondrial membrane potential and mitochondrial reactive oxygen species (mtROS) were assessed using 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine, iodide (mitochondrial membrane potential dye) and mitochondrial ROS dye, respectively. Ano1 is expressed in RLMVECs and is enriched in the mitochondria. Activation of Ano1 with Eact reduced RLMVEC counts through increased apoptosis. Ano1 knockdown blocked the effects of Eact. Ano1 activation increased mtROS, reduced mitochondrial membrane potential, increased p38 phosphorylation, and induced release of apoptosis-inducing factor. mtROS inhibition attenuated Eact-mediated p38 phosphorylation. Pulmonary artery ECs isolated from patients with idiopathic PAH (IPAH) had higher expression of Ano1 and increased cell counts compared with control subjects. Eact treatment reduced cell counts in IPAH cells, which was associated with increased apoptosis. In summary, Ano1 is expressed in lung EC mitochondria. Activation of Ano1 promotes apoptosis of pulmonary ECs and human IPAH-pulmonary artery ECs, likely via increased mtROS and p38 phosphorylation, leading to apoptosis.


Asunto(s)
Anoctamina-1/agonistas , Apoptosis/efectos de los fármacos , Benzamidas/farmacología , Proliferación Celular/efectos de los fármacos , Células Endoteliales/efectos de los fármacos , Pulmón/irrigación sanguínea , Transducción de Señal/efectos de los fármacos , Tiazoles/farmacología , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Animales , Anoctamina-1/metabolismo , Estudios de Casos y Controles , Hipoxia de la Célula , Células Cultivadas , Células Endoteliales/enzimología , Células Endoteliales/patología , Hipertensión Pulmonar Primaria Familiar/enzimología , Hipertensión Pulmonar Primaria Familiar/patología , Humanos , Mitocondrias/efectos de los fármacos , Mitocondrias/enzimología , Mitocondrias/patología , Proteínas de Neoplasias/metabolismo , Estrés Oxidativo/efectos de los fármacos , Ratas , Especies Reactivas de Oxígeno/metabolismo
5.
J Physiol ; 596(5): 827-855, 2018 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-29313986

RESUMEN

KEY POINTS: Abnormal mitochondrial morphology and function in cardiomyocytes are frequently observed under persistent Gq protein-coupled receptor (Gq PCR) stimulation. Cardiac signalling mechanisms for regulating mitochondrial morphology and function under pathophysiological conditions in the heart are still poorly understood. We demonstrate that a downstream kinase of Gq PCR, protein kinase D (PKD) induces mitochondrial fragmentation via phosphorylation of dynamin-like protein 1 (DLP1), a mitochondrial fission protein. The fragmented mitochondria enhance reactive oxygen species generation and permeability transition pore opening in mitochondria, which initiate apoptotic signalling activation. This study identifies a novel PKD-specific substrate in cardiac mitochondria and uncovers the role of PKD on cardiac mitochondria, with special emphasis on the molecular mechanism(s) underlying mitochondrial injury with abnormal mitochondrial morphology under persistent Gq PCR stimulation. These findings provide new insights into the molecular basis of cardiac mitochondrial physiology and pathophysiology, linking Gq PCR signalling with the regulation of mitochondrial morphology and function. ABSTRACT: Regulation of mitochondrial morphology is crucial for the maintenance of physiological functions in many cell types including cardiomyocytes. Small and fragmented mitochondria are frequently observed in pathological conditions, but it is still unclear which cardiac signalling pathway is responsible for regulating the abnormal mitochondrial morphology in cardiomyocytes. Here we demonstrate that a downstream kinase of Gq protein-coupled receptor (Gq PCR) signalling, protein kinase D (PKD), mediates pathophysiological modifications in mitochondrial morphology and function, which consequently contribute to the activation of apoptotic signalling. We show that Gq PCR stimulation induced by α1 -adrenergic stimulation mediates mitochondrial fragmentation in a fission- and PKD-dependent manner in H9c2 cardiac myoblasts and rat neonatal cardiomyocytes. Upon Gq PCR stimulation, PKD translocates from the cytoplasm to the outer mitochondrial membrane (OMM) and phosphorylates a mitochondrial fission protein, dynamin-like protein 1 (DLP1), at S637. PKD-dependent phosphorylation of DLP1 initiates DLP1 association with the OMM, which then enhances mitochondrial fragmentation, mitochondrial superoxide generation, mitochondrial permeability transition pore opening and apoptotic signalling. Finally, we demonstrate that DLP1 phosphorylation at S637 by PKD occurs in vivo using ventricular tissues from transgenic mice with cardiac-specific overexpression of constitutively active Gαq protein. In conclusion, Gq PCR-PKD signalling induces mitochondrial fragmentation and dysfunction via PKD-dependent DLP1 phosphorylation in cardiomyocytes. This study is the first to identify a novel PKD-specific substrate, DLP1 in mitochondria, as well as the functional role of PKD in cardiac mitochondria. Elucidation of these molecular mechanisms by which PKD-dependent enhanced fission mediates cardiac mitochondrial injury will provide novel insight into the relationship among mitochondrial form, function and Gq PCR signalling.


Asunto(s)
Dinaminas/metabolismo , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/metabolismo , Mitocondrias/patología , Dinámicas Mitocondriales , Miocitos Cardíacos/patología , Proteína Quinasa C/metabolismo , Animales , Ratones , Ratones Transgénicos , Mitocondrias/metabolismo , Proteínas de Transporte de Membrana Mitocondrial , Poro de Transición de la Permeabilidad Mitocondrial , Miocitos Cardíacos/metabolismo , Fosforilación , Ratas , Ratas Sprague-Dawley , Transducción de Señal
6.
Handb Exp Pharmacol ; 240: 129-156, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28194521

RESUMEN

Mitochondrial Ca2+ uptake is crucial for an array of cellular functions while an imbalance can elicit cell death. In this chapter, we briefly reviewed the various modes of mitochondrial Ca2+ uptake and our current understanding of mitochondrial Ca2+ homeostasis in regards to cell physiology and pathophysiology. Further, this chapter focuses on the molecular identities, intracellular regulators as well as the pharmacology of mitochondrial Ca2+ uniporter complex.


Asunto(s)
Canales de Calcio/fisiología , Animales , Calcio/metabolismo , Canales de Calcio/química , Canales de Calcio/efectos de los fármacos , Metabolismo Energético , Homeostasis , Humanos , Mitocondrias/metabolismo
7.
Am J Physiol Cell Physiol ; 311(1): C67-80, 2016 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-27122161

RESUMEN

Mitochondrial Ca(2+) homeostasis, the Ca(2+) influx-efflux balance, is responsible for the control of numerous cellular functions, including energy metabolism, generation of reactive oxygen species, spatiotemporal dynamics of Ca(2+) signaling, and cell growth and death. Recent discovery of the molecular identity of the mitochondrial Ca(2+) uniporter (MCU) provides new possibilities for application of genetic approaches to study the mitochondrial Ca(2+) influx mechanism in various cell types and tissues. In addition, the subsequent discovery of various auxiliary subunits associated with MCU suggests that mitochondrial Ca(2+) uptake is not solely regulated by a single protein (MCU), but likely by a macromolecular protein complex, referred to as the MCU-protein complex (mtCUC). Moreover, recent reports have shown the potential role of MCU posttranslational modifications in the regulation of mitochondrial Ca(2+) uptake through mtCUC. These observations indicate that mtCUCs form a local signaling complex at the inner mitochondrial membrane that could significantly regulate mitochondrial Ca(2+) handling, as well as numerous mitochondrial and cellular functions. In this review we discuss the current literature on mitochondrial Ca(2+) uptake mechanisms, with a particular focus on the structure and function of mtCUC, as well as its regulation by signal transduction pathways, highlighting current controversies and discrepancies.


Asunto(s)
Canales de Calcio/metabolismo , Señalización del Calcio , Mitocondrias/metabolismo , Membranas Mitocondriales/metabolismo , Animales , Canales de Calcio/química , Canales de Calcio/genética , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Homeostasis , Humanos , Activación del Canal Iónico , Fosforilación , Procesamiento Proteico-Postraduccional , Estructura Cuaternaria de Proteína , Subunidades de Proteína , Procesamiento Postranscripcional del ARN , Relación Estructura-Actividad , Transcripción Genética
8.
J Mol Cell Cardiol ; 79: 203-11, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25479336

RESUMEN

BACKGROUND: The most common inherited cardiac arrhythmia, LQT1, is due to IKs potassium channel mutations and is linked to high risk of adrenergic-triggered cardiac events. We recently showed that although exercise-triggered events are very well treated by ß-blockers for these patients, acute arousal-triggered event rate were not significantly reduced after beta-blocker treatment, suggesting that the mechanisms underlying arousal-triggered arrhythmias may be different from those during exercise. IKs is strongly regulated by ß-adrenergic receptor (ß-AR) signaling, but little is known about the role of α1-AR-mediated regulation. METHODS AND RESULTS: Here we show, using a combination of cellular electrophysiology and computational modeling, that IKs phosphorylation and α1-AR regulation via activation of calcium-dependent PKC isoforms (cPKC) may be a key mechanism to control channel voltage-dependent activation and consequently action potential duration (APD) in response to adrenergic-stimulus. We show that simulated mutation-specific combined adrenergic effects (ß+α) on APD were strongly correlated to acute stress-triggered cardiac event rate for patients while ß-AR effects alone were not. CONCLUSION: We were able to show that calcium-dependent PKC signaling is key to normal QT shortening during acute arousal and when impaired, correlates with increased rate of sudden arousal-triggered cardiac events. Our study suggests that the acute α1-AR-cPKC regulation of IKs is important for QT shortening in "fight-or-flight" response and is linked to decreased risk of sudden emotion/arousal-triggered cardiac events in LQT1 patients.


Asunto(s)
Nivel de Alerta , Calcio/metabolismo , Emociones , Activación del Canal Iónico , Canal de Potasio KCNQ1/metabolismo , Síndrome de QT Prolongado/fisiopatología , Canales de Potasio con Entrada de Voltaje/metabolismo , Proteína Quinasa C/metabolismo , Potenciales de Acción , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Células HEK293 , Humanos , Isoenzimas/metabolismo , Canal de Potasio KCNQ1/genética , Síndrome de QT Prolongado/genética , Proteínas Mutantes/metabolismo , Mutación/genética , Fosforilación , Canales de Potasio con Entrada de Voltaje/genética , Modelos de Riesgos Proporcionales , Receptores Adrenérgicos alfa/metabolismo , Receptores Adrenérgicos beta/metabolismo , Factores de Riesgo , Transducción de Señal
9.
Biochem Biophys Res Commun ; 465(3): 464-70, 2015 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-26277396

RESUMEN

Protein kinase C (PKC) plays key roles in the regulation of signal transduction and cellular function in various cell types. At least ten PKC isoforms have been identified and intracellular localization and trafficking of these individual isoforms are important for regulation of enzyme activity and substrate specificity. PKC can be activated downstream of Gq-protein coupled receptor (GqPCR) signaling and translocate to various cellular compartments including plasma membrane (PM). Recent reports suggested that different types of GqPCRs would activate different PKC isoforms (classic, novel and atypical PKCs) with different trafficking patterns. However, the knowledge of isoform-specific activation of PKC by each GqPCR is limited. α1-Adrenoceptor (α1-AR) is one of the GqPCRs highly expressed in the cardiovascular system. In this study, we examined the isoform-specific dynamic translocation of PKC in living HEK293T cells by α1-AR stimulation (α1-ARS). Rat PKCα, ßI, ßII, δ, ε and ζ fused with GFP at C-term were co-transfected with human α1A-AR into HEK293T cells. The isoform-specific dynamic translocation of PKC in living HEK293T cells by α1-ARS using phenylephrine was measured by confocal microscopy. Before stimulation, GFP-PKCs were localized at cytosolic region. α1-ARS strongly and rapidly translocated a classical PKC (cPKC), PKCα, (<30 s) to PM, with PKCα returning diffusively into the cytosol within 5 min. α1-ARS rapidly translocated other cPKCs, PKCßI and PKCßII, to the PM (<30 s), with sustained membrane localization. One novel PKC (nPKC), PKCε, but not another nPKC, PKCδ, was translocated by α1-AR stimulation to the PM (<30 s) and its membrane localization was also sustained. Finally, α1-AR stimulation did not cause a diacylglycerol-insensitive atypical PKC, PKCζ translocation. Our data suggest that PKCα, ß and ε activation may underlie physiological and pathophysiological responses of α1-AR signaling for the phosphorylation of membrane-associated substrates including ion-channel and transporter proteins in the cardiovascular system.


Asunto(s)
Membrana Celular/metabolismo , Proteína Quinasa C/metabolismo , Receptores Adrenérgicos alfa 1/metabolismo , Transducción de Señal/fisiología , Células HEK293 , Humanos , Isoformas de Proteínas/metabolismo , Transporte de Proteínas/fisiología
10.
Circ Res ; 110(1): 59-70, 2012 Jan 06.
Artículo en Inglés | MEDLINE | ID: mdl-22076634

RESUMEN

RATIONALE: The Rad-Gem/Kir-related family (RGKs) consists of small GTP-binding proteins that strongly inhibit the activity of voltage-gated calcium channels. Among RGKs, Rem1 is strongly and specifically expressed in cardiac tissue. However, the physiological role and regulation of RGKs, and Rem1 in particular, are largely unknown. OBJECTIVE: To determine if Rem1 function is physiologically regulated by adrenergic signaling and thus impacts voltage-gated L-type calcium channel (VLCC) activity in the heart. METHODS AND RESULTS: We found that activation of protein kinase D1, a protein kinase downstream of α(1)-adrenergic signaling, leads to direct phosphorylation of Rem1 at Ser18. This results in an increase of the channel activity and plasma membrane expression observed by using a combination of electrophysiology, live cell confocal microscopy, and immunohistochemistry in heterologous expression system and neonatal cardiomyocytes. In addition, we show that stimulation of α(1)-adrenergic receptor-protein kinase D1-Rem1 signaling increases transverse-tubule VLCC expression that results in increased L-type Ca(2+) current density in adult ventricular myocytes. CONCLUSION: The α(1)-adrenergic stimulation releases Rem1 inhibition of VLCCs through direct phosphorylation of Rem1 at Ser18 by protein kinase D1, resulting in an increase of the channel activity and transverse-tubule expression. Our results uncover a novel molecular regulatory mechanism of VLCC trafficking and function in the heart and provide the first demonstration of physiological regulation of RGK function.


Asunto(s)
Canales de Calcio Tipo L/fisiología , Miocitos Cardíacos/fisiología , Proteínas Quinasas/fisiología , Transporte de Proteínas/fisiología , Receptores Adrenérgicos alfa 1/fisiología , Transducción de Señal/fisiología , Animales , Membrana Celular/fisiología , Células Cultivadas , Masculino , Microtúbulos/fisiología , Modelos Animales , Proteínas de Unión al GTP Monoméricas/fisiología , Miocitos Cardíacos/citología , Técnicas de Placa-Clamp , Fosforilación , Proteína Quinasa C , Ratas , Ratas Sprague-Dawley
11.
Physiol Rep ; 12(6): e15989, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38538007

RESUMEN

Cardiac fibroblasts (CFs) are an attractive target for reducing pathological cardiac remodeling, and understanding the underlying mechanisms of these processes is the key to develop successful therapies for treating the pressure-overloaded heart. CF-specific knockout (KO) mouse lines with a Cre recombinase under the control of human TCF21 (hTCF21) promoter and/or an adeno-associated virus serotype 9 (AAV9)-hTCF21 system provide a powerful tool for understanding CF biology in vivo. Although a variety of rat disease models are vital for the research of cardiac fibrosis similar to mouse models, there are few rat models that employ cardiac cell-specific conditional gene modification, which has hindered the development and translational relevance of cardiac disease models. In addition, to date, there are no reports of gene manipulation specifically in rat CFs in vivo. Here, we report a simplified CF-specific rat transgenic model using an AAV9-hTCF21 system that achieved a CF-specific expression of transgene in adult rat hearts. Moreover, we successfully applied this approach to specifically manipulate mitochondrial morphology in quiescent CFs. In summary, this model will allow us to develop fast and simple rat CF-specific transgenic models for studying cardiovascular diseases in vivo.


Asunto(s)
Cardiomiopatías , Cardiopatías , Ratones , Animales , Ratas , Humanos , Miocitos Cardíacos/metabolismo , Dependovirus/genética , Cardiopatías/patología , Ratones Noqueados , Fibroblastos/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo
12.
Circulation ; 125(16): 1988-96, 2012 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-22456477

RESUMEN

BACKGROUND: ß-Adrenergic stimulation is the main trigger for cardiac events in type 1 long-QT syndrome (LQT1). We evaluated a possible association between ion channel response to ß-adrenergic stimulation and clinical response to ß-blocker therapy according to mutation location. METHODS AND RESULTS: The study sample comprised 860 patients with genetically confirmed mutations in the KCNQ1 channel. Patients were categorized into carriers of missense mutations located in the cytoplasmic loops (C loops), membrane-spanning domain, C/N terminus, and nonmissense mutations. There were 27 aborted cardiac arrest and 78 sudden cardiac death events from birth through 40 years of age. After multivariable adjustment for clinical factors, the presence of C-loop mutations was associated with the highest risk for aborted cardiac arrest or sudden cardiac death (hazard ratio versus nonmissense mutations=2.75; 95% confidence interval, 1.29-5.86; P=0.009). ß-Blocker therapy was associated with a significantly greater reduction in the risk of aborted cardiac arrest or sudden cardiac death among patients with C-loop mutations than among all other patients (hazard ratio=0.12; 95% confidence interval, 0.02-0.73; P=0.02; and hazard ratio=0.82; 95% confidence interval, 0.31-2.13; P=0.68, respectively; P for interaction=0.04). Cellular expression studies showed that membrane spanning and C-loop mutations produced a similar decrease in current, but only C-loop mutations showed a pronounced reduction in channel activation in response to ß-adrenergic stimulation. CONCLUSIONS: Patients with C-loop missense mutations in the KCNQ1 channel exhibit a high risk for life-threatening events and derive a pronounced benefit from treatment with ß-blockers. Reduced channel activation after sympathetic activation can explain the increased clinical risk and response to therapy in patients with C-loop mutations.


Asunto(s)
Canal de Potasio KCNQ1/genética , Mutación , Síndrome de Romano-Ward/genética , Adolescente , Antagonistas Adrenérgicos beta/uso terapéutico , Adulto , Niño , Femenino , Predisposición Genética a la Enfermedad , Paro Cardíaco/tratamiento farmacológico , Paro Cardíaco/genética , Humanos , Masculino , Riesgo , Síndrome de Romano-Ward/tratamiento farmacológico , Resultado del Tratamiento , Adulto Joven
13.
Am J Physiol Heart Circ Physiol ; 305(12): H1736-51, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24124188

RESUMEN

Ca(+) influx to mitochondria is an important trigger for both mitochondrial dynamics and ATP generation in various cell types, including cardiac cells. Mitochondrial Ca(2+) influx is mainly mediated by the mitochondrial Ca(2+) uniporter (MCU). Growing evidence also indicates that mitochondrial Ca(2+) influx mechanisms are regulated not solely by MCU but also by multiple channels/transporters. We have previously reported that skeletal muscle-type ryanodine receptor (RyR) type 1 (RyR1), which expressed at the mitochondrial inner membrane, serves as an additional Ca(2+) uptake pathway in cardiomyocytes. However, it is still unclear which mitochondrial Ca(2+) influx mechanism is the dominant regulator of mitochondrial morphology/dynamics and energetics in cardiomyocytes. To investigate the role of mitochondrial RyR1 in the regulation of mitochondrial morphology/function in cardiac cells, RyR1 was transiently or stably overexpressed in cardiac H9c2 myoblasts. We found that overexpressed RyR1 was partially localized in mitochondria as observed using both immunoblots of mitochondrial fractionation and confocal microscopy, whereas RyR2, the main RyR isoform in the cardiac sarcoplasmic reticulum, did not show any expression at mitochondria. Interestingly, overexpression of RyR1 but not MCU or RyR2 resulted in mitochondrial fragmentation. These fragmented mitochondria showed bigger and sustained mitochondrial Ca(2+) transients compared with basal tubular mitochondria. In addition, RyR1-overexpressing cells had a higher mitochondrial ATP concentration under basal conditions and showed more ATP production in response to cytosolic Ca(2+) elevation compared with nontransfected cells as observed by a matrix-targeted ATP biosensor. These results indicate that RyR1 possesses a mitochondrial targeting/retention signal and modulates mitochondrial morphology and Ca(2+)-induced ATP production in cardiac H9c2 myoblasts.


Asunto(s)
Adenosina Trifosfato/biosíntesis , Calcio/metabolismo , Mitocondrias/metabolismo , Mioblastos Cardíacos/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Animales , Señalización del Calcio/fisiología , Línea Celular , Mitocondrias/genética , Ratas , Canal Liberador de Calcio Receptor de Rianodina/genética
14.
Biochem Biophys Res Commun ; 433(2): 188-93, 2013 Apr 05.
Artículo en Inglés | MEDLINE | ID: mdl-23454381

RESUMEN

Adrenoceptor stimulation is a key determinant of cardiac excitation-contraction coupling mainly through the activation of serine/threonine kinases. However, little is known about the role of protein tyrosine kinases (PTKs) activated by adrenergic signaling on cardiac excitation-contraction coupling. A cytoplasmic tyrosine residue in ß1-adrenoceptor is estimated to regulate Gs-protein binding affinity from crystal structure studies, but the signaling pathway leading to the phosphorylation of these residues is unknown. Here we show α1-adrenergic signaling inhibits ß-adrenergically activated Ca(2+) current, Ca(2+) transients and contractile force through phosphorylation of tyrosine residues in ß1-adrenoceptor by PTK. Our results indicate that inhibition of ß-adrenoceptor-mediated Ca(2+) elevation by α1-adrenoceptor-PTK signaling serves as an important regulatory feedback mechanism when the catecholamine level increases to protect cardiomyocytes from cytosolic Ca(2+) overload.


Asunto(s)
Agonistas de Receptores Adrenérgicos alfa 1/farmacología , Acoplamiento Excitación-Contracción/efectos de los fármacos , Músculos Papilares/efectos de los fármacos , Receptores Adrenérgicos alfa 1/metabolismo , Receptores Adrenérgicos beta 1/metabolismo , Tirosina/metabolismo , Adenilil Ciclasas/metabolismo , Agonistas Adrenérgicos beta/farmacología , Antagonistas Adrenérgicos beta/farmacología , Animales , Señalización del Calcio/efectos de los fármacos , Citosol/metabolismo , Ventrículos Cardíacos/efectos de los fármacos , Humanos , Técnicas In Vitro , Isoproterenol/farmacología , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Músculos Papilares/fisiología , Técnicas de Placa-Clamp , Fenilefrina/farmacología , Fosforilación , Propanolaminas/farmacología , Ratas
15.
JACC Basic Transl Sci ; 8(3): 239-254, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37034280

RESUMEN

Intermittent fasting (IF) extends life span via pleotropic mechanisms, but one important molecular mediator is adenosine monophosphate-activated protein kinase (AMPK). AMPK enhances lipid metabolism and modulates microtubule dynamics. Dysregulation of these molecular pathways causes right ventricular (RV) failure in patients with pulmonary arterial hypertension. In rodent pulmonary arterial hypertension, IF activates RV AMPK, which restores mitochondrial and peroxisomal morphology and restructures mitochondrial and peroxisomal lipid metabolism protein regulation. In addition, IF increases electron transport chain protein abundance and activity in the right ventricle. Echocardiographic and hemodynamic measures of RV function are positively associated with fatty acid oxidation and electron transport chain protein levels. IF also combats heightened microtubule density, which normalizes transverse tubule structure.

16.
bioRxiv ; 2023 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-37577584

RESUMEN

MCU is widely recognized as a responsible gene for encoding a pore-forming subunit of highly mitochondrial-specific and Ca 2+ -selective channel, mitochondrial Ca 2+ uniporter complex (mtCUC). Here, we report a novel short variant derived from the MCU gene (termed MCU-S) which lacks mitochondria-targeted sequence and forms a Ca 2+ - permeable channel outside of mitochondria. MCU-S was ubiquitously expressed in all cell-types/tissues, with particularly high expression in human platelets. MCU-S formed Ca 2+ channels at the plasma membrane, which exhibited similar channel properties to those observed in mtCUC. MCU-S channels at the plasma membrane served as an additional Ca 2+ influx pathway for platelet activation. Our finding is completely distinct from the originally reported MCU gene function and provides novel insights into the molecular basis of MCU variant-dependent cellular Ca 2+ handling.

17.
J Cardiovasc Electrophysiol ; 22(2): 193-200, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20662986

RESUMEN

UNLABELLED: BACKGROUND: Data regarding possible ion channel mechanisms that predispose to ventricular tachyarrhythmias in patients with phenotype-negative long-QT syndrome (LQTS) are limited. METHODS AND RESULTS: We carried out cellular expression studies for the S349W mutation in the KCNQ1 channel, which was identified in 15 patients from the International LQTS Registry who experienced a high rate of cardiac events despite lack of significant QTc prolongation. The clinical outcome of S349W mutation carriers was compared with that of QTc-matched carriers of haploinsufficient missense (n = 30) and nonsense (n = 45) KCNQ1 mutations. The channels containing the mutant S349W subunit showed a mild reduction in current (<50%), in the haploinsuficient range, with an increase in maximal conductance compared with wild-type channels. In contrast, expression of the S349W mutant subunit produced a pronounced effect on both the voltage dependence of activation and the time constant of activation, while haploinsuficient channels showed no effect on either parameter. The cumulative probability of cardiac events from birth through age 20 years was significantly higher among S349W mutation carriers (58%) as compared with carriers of QTc-matched haploinsufficent missense (21%, P = 0.004) and nonsense (25%, P = 0.01) mutations. CONCLUSIONS: The S349W mutation in the KCNQ1 potassium channel exerts a relatively mild effect on the ion channel current, whereas an increase in conductance compensates for impaired voltage activation of the channel. The changes observed in voltage activation of the channel may underlie the mechanisms predisposing to arrhythmic risk among LQTS patients with a normal-range QTc.


Asunto(s)
Muerte Súbita Cardíaca , Predisposición Genética a la Enfermedad/genética , Activación del Canal Iónico/genética , Canal de Potasio KCNQ1/genética , Síndrome de QT Prolongado/genética , Niño , Femenino , Genotipo , Humanos , Masculino , Fenotipo , Polimorfismo de Nucleótido Simple
18.
J Am Soc Nephrol ; 21(12): 2117-29, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21088294

RESUMEN

SeSAME/EAST syndrome is a channelopathy consisting of a hypokalemic, hypomagnesemic, metabolic alkalosis associated with seizures, sensorineural deafness, ataxia, and developmental abnormalities. This disease links to autosomal recessive mutations in KCNJ10, which encodes the Kir4.1 potassium channel, but the functional consequences of these mutations are not well understood. In Xenopus oocytes, all of the disease-associated mutant channels (R65P, R65P/R199X, G77R, C140R, T164I, and A167V/R297C) had decreased K(+) current (0 to 23% of wild-type levels). Immunofluorescence demonstrated decreased surface expression of G77R, C140R, and A167V expressed in HEK293 cells. When we coexpressed mutant and wild-type subunits to mimic the heterozygous state, R199X, C140R, and G77R currents decreased to 55, 40, and 20% of wild-type levels, respectively, suggesting that carriers of these mutations may present with an abnormal phenotype. Because Kir4.1 subunits can form heteromeric channels with Kir5.1, we coexpressed the aforementioned mutants with Kir5.1 and found that currents were reduced at least as much as observed when we expressed mutants alone. Reduction of pH(i) from approximately 7.4 to 6.8 significantly decreased currents of all mutants except R199X but did not affect wild-type channels. In conclusion, perturbed pH gating may underlie the loss of channel function for the disease-associated mutant Kir4.1 channels and may have important physiologic consequences.


Asunto(s)
Canales de Potasio Rectificados Internamente Asociados a la Proteína G/genética , Pérdida Auditiva Sensorineural/genética , Canal de Potasio Kv.1.1/genética , Mutación , Convulsiones/genética , Alcalosis/genética , Alcalosis/fisiopatología , Análisis de Varianza , Animales , Ataxia/genética , Ataxia/fisiopatología , Técnica del Anticuerpo Fluorescente , Predisposición Genética a la Enfermedad , Células HEK293/metabolismo , Pérdida Auditiva Sensorineural/fisiopatología , Humanos , Hipopotasemia/genética , Hipopotasemia/fisiopatología , Immunoblotting , Discapacidad Intelectual/genética , Discapacidad Intelectual/fisiopatología , Modelos Animales , Biología Molecular , Oocitos , Convulsiones/fisiopatología , Síndrome , Xenopus laevis
19.
Int J Cardiol ; 332: 70-77, 2021 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-33675888

RESUMEN

BACKGROUND: Premature atrial contractions (PACs) are associated with increased risk of atrial fibrillation (AF) and ischemic stroke. Although lifestyle and risk factor modification reduces AF incidence, their relationship to PACs frequency is unclear. We assessed the association of Life's Simple 7 (LS7) and individual LS7 factors in midlife with PACs frequency in late life in the Atherosclerosis Risk in Communities (ARIC) Study. METHODS: We followed 1924 participants from ARIC clinic Visit 3 (1993--95) to Visit 6 (2016-17) when a 2-week continuous heart rhythm monitor (Zio®XT Patch) was applied. LS7 factors were assessed at Visit 3 and a composite score was calculated. PACs frequency was categorized as minimal (<0.1%), occasional (≥0.1%-5%) and frequent (>5%). Logistic regression was used to evaluate the association of LS7 score and individual factors with PACs frequency. RESULTS: Each 1-point LS7 score increase was associated with lower odds of frequent PACs vs. no PACs (OR [95% CI]: 0.87 [0.78, 0.98]) and frequent PACs vs. occasional PACs (OR [95% CI]: 0.88 [0.79, 0.98]). Of the individual LS7 factors, compared with ideal physical activity, poor physical activity was associated with 81% higher odds of frequent PACs vs. no PACs. Compared with ideal BMI, poor BMI was associated with 41% higher odds of occasional PACs vs. no PACs. CONCLUSION: Lifestyle risk factors, particularly physical activity and BMI, are associated with higher odds of PACs frequency. More research is needed to determine whether modifying these risk factors in midlife would prevent frequent PACs, and thereby prevent AF and stroke in older age.


Asunto(s)
Aterosclerosis , Complejos Atriales Prematuros , Anciano , Aterosclerosis/diagnóstico , Aterosclerosis/epidemiología , Complejos Atriales Prematuros/diagnóstico , Complejos Atriales Prematuros/epidemiología , Ejercicio Físico , Humanos , Estudios Prospectivos , Medición de Riesgo , Factores de Riesgo
20.
JCI Insight ; 6(12)2021 06 22.
Artículo en Inglés | MEDLINE | ID: mdl-33974567

RESUMEN

Right ventricular (RV) fibrosis is a key feature of maladaptive RV hypertrophy and dysfunction and is associated with poor outcomes in pulmonary hypertension (PH). However, mechanisms and therapeutic strategies to mitigate RV fibrosis remain unrealized. Previously, we identified that cardiac fibroblast α7 nicotinic acetylcholine receptor (α7 nAChR) drives smoking-induced RV fibrosis. Here, we sought to define the role of α7 nAChR in RV dysfunction and fibrosis in the settings of RV pressure overload as seen in PH. We show that RV tissue from PH patients has increased collagen content and ACh expression. Using an experimental rat model of PH, we demonstrate that RV fibrosis and dysfunction are associated with increases in ACh and α7 nAChR expression in the RV but not in the left ventricle (LV). In vitro studies show that α7 nAChR activation leads to an increase in adult ventricular fibroblast proliferation and collagen content mediated by a Ca2+/epidermal growth factor receptor (EGFR) signaling mechanism. Pharmacological antagonism of nAChR decreases RV collagen content and improves RV function in the PH model. Furthermore, mice lacking α7 nAChR exhibit improved RV diastolic function and have lower RV collagen content in response to persistently increased RV afterload, compared with WT controls. These finding indicate that enhanced α7 nAChR signaling is an important mechanism underlying RV fibrosis and dysfunction, and targeted inhibition of α7 nAChR is a potentially novel therapeutic strategy in the setting of increased RV afterload.


Asunto(s)
Ventrículos Cardíacos , Hipertensión Pulmonar , Receptor Nicotínico de Acetilcolina alfa 7 , Animales , Femenino , Fibrosis , Células HEK293 , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/patología , Humanos , Hipertensión Pulmonar/metabolismo , Hipertensión Pulmonar/patología , Masculino , Ratas , Ratas Sprague-Dawley , Función Ventricular Derecha/fisiología , Receptor Nicotínico de Acetilcolina alfa 7/genética , Receptor Nicotínico de Acetilcolina alfa 7/metabolismo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA