RESUMO
The mechanistic target of rapamycin (mTOR) promotes pathological remodeling in the heart by activating ribosomal biogenesis and mRNA translation. Inhibition of mTOR in cardiomyocytes is protective; however, a detailed role of mTOR in translational regulation of specific mRNA networks in the diseased heart is unknown. We performed cardiomyocyte genome-wide sequencing to define mTOR-dependent gene expression control at the level of mRNA translation. We identify the muscle-specific protein Cullin-associated NEDD8-dissociated protein 2 (Cand2) as a translationally upregulated gene, dependent on the activity of mTOR. Deletion of Cand2 protects the myocardium against pathological remodeling. Mechanistically, we show that Cand2 links mTOR signaling to pathological cell growth by increasing Grk5 protein expression. Our data suggest that cell-type-specific targeting of mTOR might have therapeutic value against pathological cardiac remodeling.
Assuntos
Miócitos Cardíacos , Remodelação Ventricular , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Proteínas Musculares , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Transdução de Sinais , Fatores de Transcrição , Regulação para Cima , Remodelação Ventricular/genéticaRESUMO
The number and activity of T cell subsets in the atherosclerotic plaques are critical for the prognosis of patients with acute coronary syndrome. ß2 Integrin activation is pivotal for T cell recruitment and correlates with future cardiac events. Despite this knowledge, differential regulation of adhesiveness in T cell subsets has not been explored yet. In this study, we show that in human T cells, SDF-1α-mediated ß2 integrin activation is driven by a, so far, not-described reactive oxidative species (ROS)-regulated calcium influx. Furthermore, we show that CD4+CD28null T cells represent a highly reactive subset showing 25-fold stronger ß2 integrin activation upon SDF-1α stimulation compared with CD28+ T cells. Interestingly, ROS-dependent Ca release was much more prevalent in the pathogenetically pivotal CD28null subset compared with the CD28+ T cells, whereas the established mediators of the classical pathways for ß2 integrin activation (PKC, PI3K, and PLC) were similarly activated in both T cell subsets. Thus, interference with the calcium flux attenuates spontaneous adhesion of CD28null T cells from acute coronary syndrome patients, and calcium ionophores abolished the observed differences in the adhesion properties between CD28+ and CD28null T cells. Likewise, the adhesion of these T cell subsets was indistinguishable in the presence of exogenous ROS/H2O2 Together, these data provide a molecular explanation of the role of ROS in pathogenesis of plaque destabilization.
Assuntos
Síndrome Coronariana Aguda/imunologia , Antígenos CD18/imunologia , Linfócitos T CD4-Positivos/imunologia , Sinalização do Cálcio/imunologia , Espécies Reativas de Oxigênio/imunologia , Síndrome Coronariana Aguda/patologia , Antígenos CD28/imunologia , Linfócitos T CD4-Positivos/patologia , Quimiocina CXCL12/imunologia , Feminino , Humanos , MasculinoRESUMO
BACKGROUND: Atrial septal defects (ASD) following endovascular mitral valve clipping are potentially hemodynamically relevant complications. Immediate closure with an occluder can represent a safe and effective treatment. An 81-year-old female patient suffering from severe dyspnea due to previously known severe mitral valve regurgitation was scheduled for elective mitral valve clipping. The clip was successfully implanted. Removal of the transseptal cannula resulted in a sudden drop in oxygen saturation and systolic blood pressure as well as an immediate increase in central venous pressure. An iatrogenic left-right shunt was observed at the atrial level with a relevant shunt volume. Immediate closure using an atrial septal occluder successfully restored the oxygen saturation and hemodynamic parameters. CONCLUSION: An increase in central venous pressure, reduction of systolic blood pressure or oxygen saturation after withdrawal of the transseptal cannula during mitral valve clipping should always be further investigated regarding a possible ASD.
Assuntos
Insuficiência da Valva Mitral , Valva Mitral , Idoso de 80 Anos ou mais , Pressão Sanguínea , Cateterismo Cardíaco , Pressão Venosa Central , Feminino , Humanos , Valva Mitral/cirurgia , Insuficiência da Valva Mitral/diagnóstico , Insuficiência da Valva Mitral/cirurgia , Saturação de OxigênioRESUMO
One of the greatest examples of integrated signal transduction is revealed by examination of effects mediated by AKT kinase in myocardial biology. Positioned at the intersection of multiple afferent and efferent signals, AKT exemplifies a molecular sensing node that coordinates dynamic responses of the cell in literally every aspect of biological responses. The balanced and nuanced nature of homeostatic signaling is particularly essential within the myocardial context, where regulation of survival, energy production, contractility, and response to pathological stress all flow through the nexus of AKT activation or repression. Equally important, the loss of regulated AKT activity is primarily the cause or consequence of pathological conditions leading to remodeling of the heart and eventual decompensation. This review presents an overview compendium of the complex world of myocardial AKT biology gleaned from more than a decade of research. Summarization of the widespread influence that AKT exerts upon myocardial responses leaves no doubt that the participation of AKT in molecular signaling will need to be reckoned with as a seemingly omnipresent regulator of myocardial molecular biological responses.
Assuntos
Miocárdio/enzimologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Animais , Sinalização do Cálcio/fisiologia , Cardiomiopatias/fisiopatologia , Sobrevivência Celular/fisiologia , Ativação Enzimática , Humanos , MicroRNAs/metabolismo , Mitocôndrias/enzimologia , Contração Miocárdica/fisiologia , Neovascularização Fisiológica/fisiologia , Proteínas Quinases/metabolismo , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , Caracteres Sexuais , Transdução de Sinais/fisiologiaRESUMO
[This corrects the article DOI: 10.1371/journal.ppat.1004249.].
RESUMO
BACKGROUND: To date, there are no guidelines recommending a specific prophylactic antibiotic treatment in transcatheter aortic valve replacement (TAVR). The aim of this study is to evaluate clinical data after TAVR with different periprocedural antibiotic regimens. METHODS: In May 2015 the institutional rules for periprocedural antibiotic prophylaxis were changed from 3 days to 1 day. Thus, a total of 450 consecutive TAVR patients between February 2014 and June 2016 were classified into two intention-to-treat groups: patients receiving a 1-day Cefuroxime prophylaxis (N = 225); patients receiving a 3-day Cefuroxime prophylaxis (N = 225). RESULTS: One-day Cefuroxime regimen was not associated with shorter hospitalization (3-day Cefuroxime 9 ± 4.7 vs 1-day Cefuroxime 8.9 ± 4.0; P = 0.87). Incidence of diarrhea (26.2% vs 18.2%; P = 0.04) and Clostridium difficile infections (4% vs 0.4%; P = 0.01) were significantly higher in the 3-day group. No endocarditis was registered after 1 year follow-up. There was no difference in 30-day overall mortality rate, major vascular complications, bleeding complications, pacemaker-implantation rate, paravalvular regurgitation, or acute kidney injury between patients groups. CONCLUSION: Three-day Cefuroxime prophylaxis does not seem to be advantageous compared to a shorter 1-day regimen, but even shows a significantly higher incidence of diarrhea and Clostridium difficile infection.
Assuntos
Antibacterianos/administração & dosagem , Antibioticoprofilaxia/métodos , Cefuroxima/administração & dosagem , Substituição da Valva Aórtica Transcateter/efeitos adversos , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/efeitos adversos , Antibioticoprofilaxia/efeitos adversos , Valva Aórtica/cirurgia , Estenose da Valva Aórtica/cirurgia , Cefuroxima/efeitos adversos , Feminino , Mortalidade Hospitalar , Humanos , Análise de Intenção de Tratamento , Tempo de Internação/estatística & dados numéricos , Masculino , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/prevenção & controle , Estudos Retrospectivos , Fatores de Risco , Resultado do TratamentoAssuntos
Vasos Coronários , Eletrocoagulação/métodos , Infarto do Miocárdio/etiologia , Animais , Vasos Coronários/diagnóstico por imagem , Modelos Animais de Doenças , Ecocardiografia/métodos , Eletrocoagulação/instrumentação , Feminino , Masculino , Camundongos , Agulhas , Duração da Cirurgia , Ultrassonografia Doppler em Cores , Ultrassonografia de Intervenção/métodosRESUMO
BACKGROUND: Myocardial infarction is followed by cardiac dysfunction, cellular death, and ventricular remodeling, including tissue fibrosis. S100A4 protein plays multiple roles in cellular survival, and tissue fibrosis, but the relative role of the S100A4 in the myocardium after myocardial infarction is unknown. This study aims to investigate the role of S100A4 in myocardial remodeling and cardiac function following infarct damage. METHODS AND RESULTS: S100A4 expression is low in the adult myocardium, but significantly increased following myocardial infarction. Deletion of S100A4 increased cardiac damage after myocardial infarction, whereas cardiac myocyte-specific overexpression of S100A4 protected the infarcted myocardium. Decreased cardiac function in S100A4 Knockout mice was accompanied with increased cardiac remodeling, fibrosis, and diminished capillary density in the remote myocardium. Loss of S100A4 caused increased apoptotic cell death both in vitro and in vivo in part mediated by decreased VEGF expression. Conversely, S100A4 overexpression protected cells against apoptosis in vitro and in vivo. Increased pro-survival AKT-signaling explained reduced apoptosis in S100A4 overexpressing cells. CONCLUSION: S100A4 expression protects cardiac myocytes against myocardial ischemia and is required for stabilization of cardiac function after MI.
Assuntos
Isquemia Miocárdica/genética , Isquemia Miocárdica/metabolismo , Miocárdio/metabolismo , Proteína A4 de Ligação a Cálcio da Família S100/genética , Estresse Fisiológico/genética , Animais , Morte Celular/genética , Modelos Animais de Doenças , Ecocardiografia , Expressão Gênica , Hemodinâmica , Camundongos , Camundongos Knockout , Infarto do Miocárdio/diagnóstico , Infarto do Miocárdio/genética , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/fisiopatologia , Isquemia Miocárdica/diagnóstico , Isquemia Miocárdica/fisiopatologia , Miocárdio/patologia , Proteína A4 de Ligação a Cálcio da Família S100/metabolismo , Remodelação VentricularRESUMO
Coxsackievirus B (CVB) is an enterovirus that most commonly causes a self-limited febrile illness in infants, but cases of severe infection can manifest in acute myocarditis. Chronic consequences of mild CVB infection are unknown, though there is an epidemiologic association between early subclinical infections and late heart failure, raising the possibility of subtle damage leading to late-onset dysfunction, or chronic ongoing injury due to inflammatory reactions during latent infection. Here we describe a mouse model of juvenile infection with a subclinical dose of coxsackievirus B3 (CVB3) which showed no evident symptoms, either immediately following infection or in adult mice. However following physiological or pharmacologically-induced cardiac stress, juvenile-infected adult mice underwent cardiac hypertrophy and dilation indicative of progression to heart failure. Evaluation of the vasculature in the hearts of adult mice subjected to cardiac stress showed a compensatory increase in CD31+ blood vessel formation, although this effect was suppressed in juvenile-infected mice. Moreover, CVB3 efficiently infected juvenile c-kit+ cells, and cardiac progenitor cell numbers were reduced in the hearts of juvenile-infected adult mice. These results suggest that the exhausted cardiac progenitor cell pool following juvenile CVB3 infection may impair the heart's ability to increase capillary density to adapt to increased load.
Assuntos
Infecções por Coxsackievirus/patologia , Enterovirus Humano B/patogenicidade , Fibrose/patologia , Coração/crescimento & desenvolvimento , Miócitos Cardíacos/citologia , Células-Tronco/citologia , Animais , Diferenciação Celular , Infecções por Coxsackievirus/virologia , Modelos Animais de Doenças , Feminino , Fibrose/virologia , Coração/virologia , Insuficiência Cardíaca/induzido quimicamente , Insuficiência Cardíaca/patologia , Insuficiência Cardíaca/virologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Miócitos Cardíacos/virologia , Células-Tronco/virologia , Estresse FisiológicoRESUMO
RATIONALE: The senescent cardiac phenotype is accompanied by changes in mitochondrial function and biogenesis causing impairment in energy provision. The relationship between myocardial senescence and Pim kinases deserves attention because Pim-1 kinase is cardioprotective, in part, by preservation of mitochondrial integrity. Study of the pathological effects resulting from genetic deletion of all Pim kinase family members could provide important insight about cardiac mitochondrial biology and the aging phenotype. OBJECTIVE: To demonstrate that myocardial senescence is promoted by loss of Pim leading to premature aging and aberrant mitochondrial function. METHODS AND RESULTS: Cardiac myocyte senescence was evident at 3 months in Pim triple knockout mice, where all 3 isoforms of Pim kinase family members are genetically deleted. Cellular hypertrophic remodeling and fetal gene program activation were followed by heart failure at 6 months in Pim triple knockout mice. Metabolic dysfunction is an underlying cause of cardiac senescence and instigates a decline in cardiac function. Altered mitochondrial morphology is evident consequential to Pim deletion together with decreased ATP levels and increased phosphorylated AMP-activated protein kinase, exposing an energy deficiency in Pim triple knockout mice. Expression of the genes encoding master regulators of mitochondrial biogenesis, PPARγ (peroxisome proliferator-activated receptor gamma) coactivator-1 α and ß, was diminished in Pim triple knockout hearts, as were downstream targets included in mitochondrial energy transduction, including fatty acid oxidation. Reversal of the dysregulated metabolic phenotype was observed by overexpressing c-Myc (Myc proto-oncogene protein), a downstream target of Pim kinases. CONCLUSIONS: Pim kinases prevent premature cardiac aging and maintain a healthy pool of functional mitochondria leading to efficient cellular energetics.
Assuntos
Senilidade Prematura/metabolismo , Cardiomegalia/metabolismo , Mitocôndrias Cardíacas/metabolismo , Miócitos Cardíacos/metabolismo , Proteínas Proto-Oncogênicas c-pim-1/genética , Senilidade Prematura/genética , Senilidade Prematura/patologia , Animais , Cardiomegalia/patologia , Linhagem Celular Transformada , Respiração Celular/genética , Senescência Celular/genética , Fibroblastos/citologia , Fibroblastos/metabolismo , Humanos , Camundongos , Camundongos Knockout , Miócitos Cardíacos/citologia , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , RNA Interferente Pequeno/genética , Ratos , Telômero/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Mitochondrial morphological dynamics affect the outcome of ischemic heart damage and pathogenesis. Recently, mitochondrial fission protein dynamin-related protein 1 (Drp1) has been identified as a mediator of mitochondrial morphological changes and cell death during cardiac ischemic injury. In this study, we report a unique relationship between Pim-1 activity and Drp1 regulation of mitochondrial morphology in cardiomyocytes challenged by ischemic stress. Transgenic hearts overexpressing cardiac Pim-1 display reduction of total Drp1 protein levels, increased phosphorylation of Drp1-(S637), and inhibition of Drp1 localization to the mitochondria. Consistent with these findings, adenoviral-induced Pim-1 neonatal rat cardiomyocytes (NRCMs) retain a reticular mitochondrial phenotype after simulated ischemia (sI) and decreased Drp1 mitochondrial sequestration. Interestingly, adenovirus Pim-dominant negative NRCMs show increased expression of Bcl-2 homology 3 (BH3)-only protein p53 up-regulated modulator of apoptosis (PUMA), which has been previously shown to induce Drp1 accumulation at mitochondria and increase sensitivity to apoptotic stimuli. Overexpression of the p53 up-regulated modulator of apoptosis-dominant negative adenovirus attenuates localization of Drp1 to mitochondria in adenovirus Pim-dominant negative NRCMs promotes reticular mitochondrial morphology and inhibits cell death during sI. Therefore, Pim-1 activity prevents Drp1 compartmentalization to the mitochondria and preserves reticular mitochondrial morphology in response to sI.
Assuntos
Dinaminas/metabolismo , Mitocôndrias/metabolismo , Proteínas Proto-Oncogênicas c-pim-1/fisiologia , Adenoviridae/genética , Animais , Camundongos , Camundongos Transgênicos , Miócitos Cardíacos/citologia , Fosforilação , Transporte Proteico , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , RatosRESUMO
Mechanistic target of rapamycin complex 1 (mTORC1), necessary for cellular growth, is regulated by intracellular signaling mediating inhibition of mTORC1 activation. Among mTORC1 regulatory binding partners, the role of Proline Rich AKT Substrate of 40 kDa (PRAS40) in controlling mTORC1 activity and cellular growth in response to pathological and physiological stress in the heart has never been addressed. This report shows PRAS40 is regulated by AKT in cardiomyocytes and that AKT-driven phosphorylation relieves the inhibitory function of PRAS40. PRAS40 overexpression in vitro blocks mTORC1 in cardiomyocytes and decreases pathological growth. Cardiomyocyte-specific overexpression in vivo blunts pathological remodeling after pressure overload and preserves cardiac function. Inhibition of mTORC1 by PRAS40 preferentially promotes protective mTORC2 signaling in chronic diseased myocardium. In contrast, strong PRAS40 phosphorylation by AKT allows for physiological hypertrophy both in vitro and in vivo, whereas cardiomyocyte-specific overexpression of a PRAS40 mutant lacking capacity for AKT-phosphorylation inhibits physiological growth in vivo, demonstrating that AKT-mediated PRAS40 phosphorylation is necessary for induction of physiological hypertrophy. Therefore, PRAS40 phosphorylation acts as a molecular switch allowing mTORC1 activation during physiological growth, opening up unique possibilities for therapeutic regulation of the mTORC1 complex to mitigate pathologic myocardial hypertrophy by PRAS40.
Assuntos
Cardiomegalia/metabolismo , Complexos Multiproteicos/metabolismo , Proteínas Musculares/metabolismo , Miócitos Cardíacos/metabolismo , Fosfoproteínas/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Animais , Cardiomegalia/genética , Cardiomegalia/patologia , Cardiomegalia/terapia , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina , Alvo Mecanístico do Complexo 2 de Rapamicina , Camundongos , Complexos Multiproteicos/genética , Proteínas Musculares/genética , Mutação , Miócitos Cardíacos/patologia , Fosfoproteínas/genética , Fosforilação/genética , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Serina-Treonina Quinases TOR/genéticaRESUMO
Autologous c-kit(+) cardiac progenitor cells (CPCs) are currently used in the clinic to treat heart disease. CPC-based regeneration may be further augmented by better understanding molecular mechanisms of endogenous cardiac repair and enhancement of pro-survival signaling pathways that antagonize senescence while also increasing differentiation. The prolyl isomerase Pin1 regulates multiple signaling cascades by modulating protein folding and thereby activity and stability of phosphoproteins. In this study, we examine the heretofore unexplored role of Pin1 in CPCs. Pin1 is expressed in CPCs in vitro and in vivo and is associated with increased proliferation. Pin1 is required for cell cycle progression and loss of Pin1 causes cell cycle arrest in the G1 phase in CPCs, concomitantly associated with decreased expression of Cyclins D and B and increased expression of cell cycle inhibitors p53 and retinoblastoma (Rb). Pin1 deletion increases cellular senescence but not differentiation or cell death of CPCs. Pin1 is required for endogenous CPC response as Pin1 knock-out mice have a reduced number of proliferating CPCs after ischemic challenge. Pin1 overexpression also impairs proliferation and causes G2/M phase cell cycle arrest with concurrent down-regulation of Cyclin B, p53, and Rb. Additionally, Pin1 overexpression inhibits replicative senescence, increases differentiation, and inhibits cell death of CPCs, indicating that cell cycle arrest caused by Pin1 overexpression is a consequence of differentiation and not senescence or cell death. In conclusion, Pin1 has pleiotropic roles in CPCs and may be a molecular target to promote survival, enhance repair, improve differentiation, and antagonize senescence.
Assuntos
Pontos de Checagem do Ciclo Celular/fisiologia , Diferenciação Celular/fisiologia , Senescência Celular/fisiologia , Miocárdio/metabolismo , Peptidilprolil Isomerase/biossíntese , Células-Tronco/metabolismo , Animais , Sobrevivência Celular/fisiologia , Ciclina B/genética , Ciclina B/metabolismo , Ciclina D/genética , Ciclina D/metabolismo , Camundongos , Camundongos Knockout , Miocárdio/citologia , Peptidilprolil Isomerase de Interação com NIMA , Peptidilprolil Isomerase/genética , Células-Tronco/citologia , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
RATIONALE: Adoptive transfer of cardiac progenitor cells (CPCs) has entered clinical application, despite limited mechanistic understanding of the endogenous response after myocardial infarction (MI). Extracellular matrix undergoes dramatic changes after MI and therefore might be linked to CPC-mediated repair. OBJECTIVE: To demonstrate the significance of fibronectin (Fn), a component of the extracellular matrix, for induction of the endogenous CPC response to MI. METHODS AND RESULTS: This report shows that presence of CPCs correlates with the expression of Fn during cardiac development and after MI. In vivo, genetic conditional ablation of Fn blunts CPC response measured 7 days after MI through reduced proliferation and diminished survival. Attenuated vasculogenesis and cardiogenesis during recovery were evident at the end of a 12-week follow-up period. Impaired CPC-dependent reparative remodeling ultimately leads to continuous decline of cardiac function in Fn knockout animals. In vitro, Fn protects and induces proliferation of CPCs via ß1-integrin-focal adhesion kinase-signal transducer and activator of transcription 3-Pim1 independent of Akt. CONCLUSIONS: Fn is essential for endogenous CPC expansion and repair required for stabilization of cardiac function after MI.
Assuntos
Diferenciação Celular/fisiologia , Fibronectinas/fisiologia , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Miócitos Cardíacos/metabolismo , Células-Tronco/metabolismo , Animais , Proliferação de Células , Células Cultivadas , Feminino , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Miócitos Cardíacos/citologia , Células-Tronco/citologiaRESUMO
RATIONALE: Cardiac hypertrophy results from the complex interplay of differentially regulated cascades based on the phosphorylation status of involved signaling molecules. Although numerous critical regulatory kinases and phosphatases have been identified in the myocardium, the intracellular mechanism for temporal regulation of signaling duration and intensity remains obscure. In the nonmyocyte context, control of folding, activity, and stability of proteins is mediated by the prolyl isomerase Pin1, but the role of Pin1 in the heart is unknown. OBJECTIVE: To establish the role of Pin1 in the heart. METHODS AND RESULTS: Here, we show that either genetic deletion or cardiac overexpression of Pin1 blunts hypertrophic responses induced by transaortic constriction and consequent cardiac failure in vivo. Mechanistically, we find that Pin1 directly binds to Akt, mitogen activated protein kinase (MEK), and Raf-1 in cultured cardiomyocytes after hypertrophic stimulation. Furthermore, loss of Pin1 leads to diminished hypertrophic signaling of Akt and MEK, whereas overexpression of Pin1 increases Raf-1 phosphorylation on the autoinhibitory site Ser259, leading to reduced MEK activation. CONCLUSIONS: Collectively, these data support a role for Pin1 as a central modulator of the intensity and duration of 2 major hypertrophic signaling pathways, thereby providing a novel target for regulation and control of cardiac hypertrophy.
Assuntos
Cardiomegalia/enzimologia , Miócitos Cardíacos/enzimologia , Peptidilprolil Isomerase/metabolismo , Transdução de Sinais , Animais , Cardiomegalia/diagnóstico por imagem , Cardiomegalia/patologia , Cardiomegalia/fisiopatologia , Cardiomegalia/prevenção & controle , Dependovirus/genética , Modelos Animais de Doenças , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Miócitos Cardíacos/patologia , Peptidilprolil Isomerase de Interação com NIMA , Peptidilprolil Isomerase/deficiência , Peptidilprolil Isomerase/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Interferência de RNA , Ratos , Fatores de Tempo , Transdução Genética , Transfecção , Ultrassonografia , Quinases raf/metabolismoRESUMO
BACKGROUND: The mechanistic target of rapamycin (mTOR) comprises 2 structurally distinct multiprotein complexes, mTOR complexes 1 and 2 (mTORC1 and mTORC2). Deregulation of mTOR signaling occurs during and contributes to the severity of myocardial damage from ischemic heart disease. However, the relative roles of mTORC1 versus mTORC2 in the pathogenesis of ischemic damage are unknown. METHODS AND RESULTS: Combined pharmacological and molecular approaches were used to alter the balance of mTORC1 and mTORC2 signaling in cultured cardiac myocytes and in mouse hearts subjected to conditions that mimic ischemic heart disease. The importance of mTOR signaling in cardiac protection was demonstrated by pharmacological inhibition of both mTORC1 and mTORC2 with Torin1, which led to increased cardiomyocyte apoptosis and tissue damage after myocardial infarction. Predominant mTORC1 signaling mediated by suppression of mTORC2 with Rictor similarly increased cardiomyocyte apoptosis and tissue damage after myocardial infarction. In comparison, preferentially shifting toward mTORC2 signaling by inhibition of mTORC1 with PRAS40 led to decreased cardiomyocyte apoptosis and tissue damage after myocardial infarction. CONCLUSIONS: These results suggest that selectively increasing mTORC2 while concurrently inhibiting mTORC1 signaling is a novel therapeutic approach for the treatment of ischemic heart disease.
Assuntos
Complexos Multiproteicos/antagonistas & inibidores , Complexos Multiproteicos/metabolismo , Infarto do Miocárdio/metabolismo , Isquemia Miocárdica/metabolismo , Transdução de Sinais/fisiologia , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Apoptose/fisiologia , Proteínas de Transporte/metabolismo , Humanos , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina , Alvo Mecanístico do Complexo 2 de Rapamicina , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Complexos Multiproteicos/genética , Infarto do Miocárdio/patologia , Isquemia Miocárdica/patologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/fisiologia , Naftiridinas/farmacologia , Cultura Primária de Células , Proteína Companheira de mTOR Insensível à Rapamicina , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/genéticaRESUMO
T cells infiltrate peripheral tissues to execute immunosurveillance and effector functions. For this purpose, T cells first migrate on the two-dimensional (2D) surface of endothelial cells to undergo transendothelial migration. Then they change their mode of movement to undergo migration within the three-dimensional (3D)-extracellular matrix of the infiltrated tissue. As yet, no molecular mechanisms are known, which control migration exclusively in either 2D or 3D environments. Here, we describe a signalling module that controls T-cell chemotaxis specifically in 3D environments. In chemotaxing T cells, Ras activity is spatially restricted to the lamellipodium. There, Ras initiates activation of MEK, which in turn inhibits LIM-kinase 1 activity, thereby allowing dephosphorylation of the F-actin-remodelling protein cofilin. Interference with this MEK-cofilin module by either inhibition of MEK or by knockdown of cofilin reduces speed and directionality of chemotactic migration in 3D-extracellular matrices, but not on 2D substrates. This MEK-cofilin module may have an important function in the tissue positioning of T cells during an immune response.
Assuntos
Movimento Celular , Transdução de Sinais , Linfócitos T/fisiologia , Fatores de Despolimerização de Actina/genética , Fatores de Despolimerização de Actina/metabolismo , Actinas/metabolismo , Células Cultivadas , Quimiotaxia , Técnicas de Silenciamento de Genes , Humanos , Quinases Lim/antagonistas & inibidores , Quinases de Proteína Quinase Ativadas por Mitógeno/genética , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Modelos Biológicos , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Receptores de Quimiocinas/metabolismoRESUMO
RATIONALE: Cardiac progenitor cells (CPCs) in the adult heart are used for cell-based treatment of myocardial damage, but factors determining stemness, self-renewal, and lineage commitment are poorly understood. Immortal DNA strands inherited through asymmetric chromatid segregation correlate with self-renewal of adult stem cells, but the capacity of CPCs for asymmetric segregation to retain immortal strands is unknown. Cardioprotective kinase Pim-1 increases asymmetric cell division in vivo, but the ability of Pim-1 to enhance asymmetric chromatid segregation is unknown. OBJECTIVE: We aimed to demonstrate immortal strand segregation in CPCs and the enhancement of asymmetric chromatid distribution by Pim-1 kinase. METHODS AND RESULTS: Asymmetric segregation is tracked by incorporation of bromodeoxyuridine. The CPC DNA was labeled for several generations and then blocked in second cytokinesis during chase to determine distribution of immortal versus newly synthesized strands. Intensity ratios of binucleated CPCs with bromodeoxyuridine of ≥70:30 between daughter nuclei indicative of asymmetric chromatid segregation occur with a frequency of 4.57, and asymmetric chromatid segregation is demonstrated at late mitotic phases. Asymmetric chromatid segregation is significantly enhanced by Pim-1 overexpression in CPCs (9.19 versus 4.79 in eGFP-expressing cells; P=0.006). CONCLUSIONS: Asymmetric segregation of chromatids in CPCs is increased nearly two-fold with Pim-1 kinase overexpression, indicating that Pim-1 promotes self-renewal of stem cells.
Assuntos
Proliferação de Células , Cromátides/metabolismo , Segregação de Cromossomos , Mitose , Miócitos Cardíacos/enzimologia , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , Células-Tronco/enzimologia , Animais , Bromodesoxiuridina/metabolismo , Células Cultivadas , Citocinese , Replicação do DNA , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Camundongos , Proteínas Proto-Oncogênicas c-pim-1/genética , TransfecçãoRESUMO
Nucleolar stress, characterized by loss of nucleolar integrity, has not been described in the cardiac context. In addition to ribosome biogenesis, nucleoli are critical for control of cell proliferation and stress responses. Our group previously demonstrated induction of the nucleolar protein nucleostemin (NS) in response to cardiac pathological insult. NS interacts with nucleophosmin (NPM), a marker of nucleolar stress with cytoprotective properties. The dynamic behavior of NS and NPM reveal that nucleolar disruption is an early event associated with stress response in cardiac cells. Rapid translocation of NS and NPM to the nucleoplasm and suppression of new preribosomal RNA synthesis occurs in both neonatal rat cardiomyocytes (NRCM) and cardiac progenitor cells (CPC) upon exposure to doxorubicin or actinomycin D. Silencing of NS significantly increases cell death resulting from doxorubicin treatment in CPC, whereas NPM knockdown alone induces cell death. Overexpression of either NS or NPM significantly decreases caspase 8 activity in cultured cardiomyocytes challenged with doxorubicin. The presence of altered nucleolar structures resulting from myocardial infarction in mice supports the model of nucleolar stress as a general response to pathological injury. Collectively, these findings serve as the initial description of myocardial nucleolar stress and establish the postulate that nucleoli acts as sensors of stress, regulating the cellular response to pathological insults.
Assuntos
Proteínas de Transporte/metabolismo , Nucléolo Celular/metabolismo , Miocárdio/metabolismo , Proteínas Nucleares/metabolismo , Estresse Fisiológico , Animais , Aorta/metabolismo , Aorta/patologia , Apoptose , Nucléolo Celular/patologia , Células Cultivadas , Constrição Patológica/metabolismo , Constrição Patológica/patologia , Proteínas de Ligação ao GTP , Humanos , Camundongos , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Miocárdio/patologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Nucleofosmina , RNA Ribossômico/biossíntese , Proteínas de Ligação a RNA , RatosRESUMO
BACKGROUND: Transcatheter edge-to-edge repair for severe tricuspid regurgitation (TR) is a new treatment option (t-TEER). Data on optimal antithrombotic therapy after t-TEER in patients with an indication for anticoagulation are scarce and evidence-based guideline recommendations are lacking. We sought to investigate efficacy and safety of novel oral anticoagulation (NOAC) and vitamin-K-antagonists (VKA) in patients undergoing t-TEER. METHODS: Among 78 consecutive patients with t-TEER of severe TR, 69 patients were identified with concomitant indication for oral anticoagulation. Outcomes of these patients treated with NOAC or VKA were compared over a median follow-up period of 327 (177-460) days. RESULTS: Despite elevated thromboembolic and bleeding risk scores (CHA2DS2-VASc 4.2 ± 1.1, HEMORR2HAGES 3.0 ± 1.0 and HAS-BLED 2.1 ± 0.8), only one major bleeding incidence occurred under NOAC therapy. The risk for overall (NOAC 8% vs. VKA group 26%, p = 0.044) and major bleeding events (NOAC 2% vs. VKA 21%, p = 0.010) was significantly lower in the NOAC compared to the VKA group. No significant difference was found between NOAC and VKA treatment in terms of mortality (NOAC 18% vs. VKA 16%, p = 0.865) or the combined endpoint of death, heart failure hospitalization, stroke, embolism, thrombosis, myocardial infarction, and severe bleeding (NOAC 48% vs. VKA 42%, p = 0.801). A comparison between apixaban (n = 27) and rivaroxaban (n = 16) treated patients revealed no significant differences between NOAC substances (all bleeding events apixaban 7% vs. rivaroxaban 13%, p = 0.638). CONCLUSION: Results of this study indicate that NOACs may offer a favorable risk-benefit profile for patients with concomitant indication for anticoagulation therapy following t-TEER.