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1.
J Am Heart Assoc ; 7(2)2018 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-29358191

RESUMO

BACKGROUND: Severe cardiac hypertrophy can lead to cardiac remodeling and even heart failure in the end, which is a leading cause of cardiovascular disease-related mortality worldwide. A disintegrin and metalloprotease-22 (ADAM22), a member of the transmembrane and secreted metalloendopeptidase family, participates in many biological processes, including those in the cardiovascular system. However, there is no explicit information on whether ADAM22 can regulate the process of cardiac hypertrophy; the effects that ADAM22 exerts in cardiac hypertrophy remain elusive. METHODS AND RESULTS: We observed significantly increased ADAM22 expression in failing hearts from patients with dilated cardiomyopathy and hypertrophic cardiomyopathy; the same trend was observed in mice induced by transaortic constriction and in neonatal rat cardiomyocytes treated by angiotensin II. Therefore, we constructed both cardiac-specific ADAM22 overexpression and knockout mice. At 4 weeks after transaortic constriction, cardiac-specific ADAM22 knockout, by the CRISPR/Cas9 (clustered regularly interspaced palindromic repeat (CRISPR)-Cas9) system, deteriorated the severity of cardiac hypertrophy in mice, whereas cardiac-specific ADAM22 overexpression mitigated the degrees of cardiac hypertrophy in mice. Similarly, altered ADAM22 expression modulated the angiotensin II-mediated cardiomyocyte hypertrophy in neonatal rat cardiomyocytes. After screening several signaling pathways, we found ADAM22 played a role in inhibition of protein kinase B (AKT) activation. Under the cardiac-specific ADAM22 knockout background, AKT activation was enhanced in transaortic constriction-induced mice and angiotensin II-stimulated neonatal rat cardiomyocytes, with a severe degree of cardiac hypertrophy. Treatment of a specific AKT inhibitor attenuated the transaortic constriction-enhanced AKT activation and cardiac hypertrophy in mice. CONCLUSIONS: The findings demonstrated that ADAM22 negatively regulates the AKT activation and the process of cardiac hypertrophy and may provide new insights into the pathobiological features of cardiac hypertrophy.


Assuntos
Proteínas ADAM/metabolismo , Hipertrofia Ventricular Esquerda/prevenção & controle , Miócitos Cardíacos/enzimologia , Proteínas do Tecido Nervoso/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Função Ventricular Esquerda , Remodelação Ventricular , Proteínas ADAM/deficiência , Proteínas ADAM/genética , Animais , Animais Recém-Nascidos , Cardiomiopatia Dilatada/enzimologia , Cardiomiopatia Dilatada/fisiopatologia , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/fisiopatologia , Estudos de Casos e Controles , Células Cultivadas , Modelos Animais de Doenças , Humanos , Hipertrofia Ventricular Esquerda/enzimologia , Hipertrofia Ventricular Esquerda/genética , Hipertrofia Ventricular Esquerda/fisiopatologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Miócitos Cardíacos/patologia , Proteínas do Tecido Nervoso/deficiência , Proteínas do Tecido Nervoso/genética , Ratos Sprague-Dawley , Transdução de Sinais
2.
Am J Physiol Heart Circ Physiol ; 313(2): H283-H292, 2017 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-28550180

RESUMO

PRKAG2 encodes the γ2-subunit isoform of 5'-AMP-activated protein kinase (AMPK), a heterotrimeric enzyme with major roles in the regulation of energy metabolism in response to cellular stress. Mutations in PRKAG2 have been implicated in a unique hypertrophic cardiomyopathy (HCM) characterized by cardiac glycogen overload, ventricular preexcitation, and hypertrophy. We identified a novel, de novo PRKAG2 mutation (K475E) in a neonate with prenatal onset of HCM. We aimed to investigate the cellular impact, signaling pathways involved, and therapeutic options for K475E mutation using cells stably expressing human wild-type (WT) or the K475E mutant. In human embryonic kidney-293 cells, the K475E mutation induced a marked increase in the basal phosphorylation of T172 and AMPK activity, reduced sensitivity to AMP in allosteric activation, and a loss of response to phenformin. In H9c2 cardiomyocytes, the K475E mutation induced inhibition of AMPK and reduced the response to phenformin and increases in the phosphorylation of p70S6 kinase (p70S6K) and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). Primary fibroblasts from the patient with the K475E mutation also showed marked increases in the phosphorylation of p70S6K and 4E-BP1 compared with those from age-matched, nondiseased controls. Moreover, overexpression of K475E induced hypertrophy in H9c2 cells, which was effectively reversed by treatment with rapamycin. Taken together, we have identified a novel, de novo infantile-onset PRKAG2 mutation causing HCM. Our study suggests the K475E mutation induces alteration in basal AMPK activity and results in a hypertrophy phenotype involving the mechanistic target of rapamycin signaling pathway, which can be reversed with rapamycin.NEW & NOTEWORTHY We identified a novel, de novo PRKAG2 mutation (K475E) in the cystathionine ß-synthase 3 repeat, a region critical for AMP binding but with no previous reported mutation. Our data suggest the mutation affects AMP-activated protein kinase activity, activates cell growth pathways, and results in cardiac hypertrophy, which can be reversed with rapamycin.


Assuntos
Proteínas Quinases Ativadas por AMP/genética , Cardiomiopatia Hipertrófica/genética , Mutação de Sentido Incorreto , Miócitos Cardíacos/enzimologia , Transdução de Sinais , Proteínas Quinases Ativadas por AMP/química , Proteínas Quinases Ativadas por AMP/metabolismo , Monofosfato de Adenosina/metabolismo , Cardiomiopatia Hipertrófica/tratamento farmacológico , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/fisiopatologia , Proteínas de Transporte/metabolismo , Estudos de Casos e Controles , Análise Mutacional de DNA , Ativação Enzimática , Fibroblastos/enzimologia , Fibroblastos/patologia , Predisposição Genética para Doença , Células HEK293 , Humanos , Recém-Nascido , Peptídeos e Proteínas de Sinalização Intracelular , Modelos Moleculares , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/patologia , Fenformin/farmacologia , Fenótipo , Fosfoproteínas/metabolismo , Fosforilação , Conformação Proteica , Inibidores de Proteínas Quinases/farmacologia , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologia , Relação Estrutura-Atividade , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Transfecção
3.
Hum Pathol ; 49: 27-32, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26826406

RESUMO

Complex I deficiency causes Leigh syndrome, fatal infant lactic acidosis, and neonatal cardiomyopathy. Mutations in more than 100 nuclear DNA and mitochondrial DNA genes miscode for complex I subunits or assembly factors. ACAD9 is an acyl-CoA dehydrogenase with a novel function in assembly of complex I; biallelic mutations cause progressive encephalomyopathy, recurrent Reye syndrome, and fatal cardiomyopathy. We describe the first autopsy in fatal neonatal lethal lactic acidosis due to mutations in ACAD9 that reduced complex I activity. We identified mitochondrial hyperplasia in cardiac myocytes, diaphragm muscle, and liver and renal tubules in formalin-fixed, paraffin-embedded tissue using immunohistochemistry for mitochondrial antigens. Whole-exome sequencing revealed compound heterozygous variants in the ACAD9 gene: c.187G>T (p.E63*) and c.941T>C (p.L314P). The nonsense mutation causes late infantile lethality; the missense variant is novel. Autopsy-derived fibroblasts had reduced complex I activity (53% of control) with normal activity in complexes II to IV, similar to reported cases of ACAD9 deficiency.


Assuntos
Acidose Láctica/diagnóstico , Acidose/diagnóstico , Acil-CoA Desidrogenase/deficiência , Acil-CoA Desidrogenases/genética , Erros Inatos do Metabolismo dos Aminoácidos/diagnóstico , Cardiomiopatia Hipertrófica/diagnóstico , Códon sem Sentido , Diafragma/patologia , Complexo I de Transporte de Elétrons/deficiência , Túbulos Renais/patologia , Doença de Leigh/diagnóstico , Mitocôndrias Cardíacas/patologia , Mitocôndrias Hepáticas/patologia , Mitocôndrias Musculares/patologia , Doenças Mitocondriais/diagnóstico , Insuficiência de Múltiplos Órgãos/diagnóstico , Debilidade Muscular/diagnóstico , Acidose/enzimologia , Acidose/genética , Acidose/patologia , Acidose Láctica/enzimologia , Acidose Láctica/genética , Acidose Láctica/patologia , Acil-CoA Desidrogenase/genética , Acil-CoA Desidrogenases/deficiência , Erros Inatos do Metabolismo dos Aminoácidos/enzimologia , Erros Inatos do Metabolismo dos Aminoácidos/genética , Erros Inatos do Metabolismo dos Aminoácidos/patologia , Autopsia , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/patologia , Causas de Morte , Células Cultivadas , Análise Mutacional de DNA , DNA Mitocondrial/genética , Diafragma/enzimologia , Complexo I de Transporte de Elétrons/genética , Evolução Fatal , Fibroblastos/enzimologia , Fibroblastos/patologia , Predisposição Genética para Doença , Humanos , Hiperplasia , Imuno-Histoquímica , Recém-Nascido , Túbulos Renais/enzimologia , Doença de Leigh/enzimologia , Doença de Leigh/genética , Doença de Leigh/patologia , Masculino , Mitocôndrias Cardíacas/enzimologia , Mitocôndrias Hepáticas/enzimologia , Mitocôndrias Musculares/enzimologia , Doenças Mitocondriais/enzimologia , Doenças Mitocondriais/genética , Doenças Mitocondriais/patologia , Insuficiência de Múltiplos Órgãos/enzimologia , Insuficiência de Múltiplos Órgãos/genética , Insuficiência de Múltiplos Órgãos/patologia , Debilidade Muscular/enzimologia , Debilidade Muscular/genética , Debilidade Muscular/patologia , Fenótipo , Transfecção
4.
J Cardiovasc Magn Reson ; 17: 89, 2015 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-26496977

RESUMO

BACKGROUND: Autosomal dominantly inherited PRKAG2 cardiac syndrome is due to a unique defect of the cardiac cell metabolism and has a distinctive histopathology with excess intracellular glycogen, and prognosis different from sarcomeric hypertrophic cardiomyopathy. We aimed to define the distinct characteristics of PRKAG2 using cardiovascular magnetic resonance (CMR). METHODS: CMR (1.5 T) and genetic testing were performed in two families harboring PRKAG2 mutations. On CMR, segmental analysis of left ventricular (LV) hypertrophy (LVH), function, native T1 mapping, and late gadolinium enhancement (LGE) were performed. RESULTS: Six individuals (median age 23 years, range 16-48; two females) had a PRKAG2 mutation: five with an R302Q mutation (family 1), and one with a novel H344P mutation (family 2). Three of six mutation carriers had LV mass above age and gender limits (203 g/m2, 157 g/m2 and 68 g/m2) and others (with R302Q mutation) normal LV masses. All mutation carriers had LVH in at least one segment, with the median maximal wall thickness of 13 mm (range 11-37 mm). Two R302Q mutation carriers with markedly increased LV mass (203 g/m2 and 157 g/m2) showed a diffuse pattern of hypertrophy but predominantly in the interventricular septum, while other mutation carriers exhibited a non-symmetric mid-infero-lateral pattern of hypertrophy. In family 1, the mutation negative male had a mean T1 value of 963 ms, three males with the R302Q mutation, LVH and no LGE a mean value of 918 ± 11 ms, and the oldest male with the R302Q mutation, extensive hypertrophy and LGE a mean value of 973 ms. Of six mutations carriers, two with advanced disease had LGE with 11 and 22 % enhancement of total LV volume. CONCLUSIONS: PRKAG2 cardiac syndrome may present with eccentric distribution of LVH, involving focal mid-infero-lateral pattern in the early disease stage, and more diffuse pattern but focusing on interventricular septum in advanced cases. In patients at earlier stages of disease, without LGE, T1 values may be reduced, while in the advanced disease stage T1 mapping may result in higher values caused by fibrosis. CMR is a valuable tool in detecting diffuse and focal myocardial abnormalities in PRKAG2 cardiomyopathy.


Assuntos
Proteínas Quinases Ativadas por AMP/genética , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/patologia , Hipertrofia Ventricular Esquerda/genética , Hipertrofia Ventricular Esquerda/patologia , Imagem Cinética por Ressonância Magnética , Mutação , Miocárdio/patologia , Adolescente , Adulto , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/fisiopatologia , Meios de Contraste , Análise Mutacional de DNA , Eletrocardiografia , Feminino , Fibrose , Predisposição Genética para Doença , Humanos , Hipertrofia Ventricular Esquerda/enzimologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Masculino , Meglumina , Pessoa de Meia-Idade , Compostos Organometálicos , Fenótipo , Valor Preditivo dos Testes , Função Ventricular Esquerda , Remodelação Ventricular , Adulto Jovem
5.
Int J Cardiovasc Imaging ; 31(4): 669-79, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25627778

RESUMO

Consistent protocols for the assessment of diastolic and systolic cardiac function to assure the comparability of existing data on preclinical models are missing. Calcineurin transgene (CN) mice are a preclinical model for hypertrophic and failing hearts. We aimed at evaluating left and right ventricular structural and functional remodeling in CN hearts with an optimized phenotyping protocol. We developed a protocol using techniques and indices comparable to those from human diagnostics for comprehensive in vivo cardiac screening using high-frequency echocardiography, Doppler, electrocardiography and cardiac magnetic resonance (CMR) techniques. We measured left and right ventricular dimensions and function, pulmonary and mitral flow pattern and the hearts electrophysiology non-invasively in <1 h per mouse. We found severe biventricular dilation and a drastic decline in performance in accordance with a condition of heart failure (HF), diastolic dysfunction and defects in electrical conduction in 8-week-old calcineurin transgenic mice. Echocardiography of the left ventricle was performed with and without anesthesia. In all cases absolute values on echocardiography compared with CMR were smaller for LV dimension and wall thickness, resulting in higher fractional shorting and ejection fraction. The study protocol described here opens opportunities to assess the added value of combined echocardiography, Doppler, CMR and ECG recording techniques for the diagnosis of biventricular cardiac pathologies i.e. of HF and to study symptom occurrence and disease progression non-invasively in high-throughput. Phenotyping CN hearts revealed new symptom occurrence and allowed insights into the diverse phenotype of hypertrophic failing hearts.


Assuntos
Calcineurina/genética , Cardiomiopatia Hipertrófica/diagnóstico , Insuficiência Cardíaca/diagnóstico , Ensaios de Triagem em Larga Escala/métodos , Hipertrofia Ventricular Esquerda/diagnóstico , Hipertrofia Ventricular Direita/diagnóstico , Disfunção Ventricular Esquerda/diagnóstico , Disfunção Ventricular Direita/diagnóstico , Animais , Calcineurina/metabolismo , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/fisiopatologia , Modelos Animais de Doenças , Progressão da Doença , Ecocardiografia Doppler , Eletrocardiografia , Feminino , Predisposição Genética para Doença , Insuficiência Cardíaca/enzimologia , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/fisiopatologia , Hemodinâmica , Hipertrofia Ventricular Esquerda/enzimologia , Hipertrofia Ventricular Esquerda/genética , Hipertrofia Ventricular Esquerda/fisiopatologia , Hipertrofia Ventricular Direita/enzimologia , Hipertrofia Ventricular Direita/genética , Hipertrofia Ventricular Direita/fisiopatologia , Imagem por Ressonância Magnética , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Cadeias Pesadas de Miosina/genética , Fenótipo , Valor Preditivo dos Testes , Regiões Promotoras Genéticas , Disfunção Ventricular Esquerda/enzimologia , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/fisiopatologia , Disfunção Ventricular Direita/enzimologia , Disfunção Ventricular Direita/genética , Disfunção Ventricular Direita/fisiopatologia , Função Ventricular Esquerda , Função Ventricular Direita , Miosinas Ventriculares/genética , Remodelação Ventricular
6.
J Mol Cell Cardiol ; 77: 53-63, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25280781

RESUMO

The mechanisms linking the expression of sarcomeric mutant proteins to the development of pathological hypertrophy in hypertrophic cardiomyopathy (HCM) remain poorly understood. We investigated the role of the plasma membrane Ca(2+)-ATPase PMCA4 in the HCM phenotype using a transgenic model that expresses mutant (Glu180Gly) α-tropomyosin (Tm180) in heart. Immunoblot analysis revealed that cardiac PMCA4 expression was upregulated early in Tm180 disease pathogenesis. This was accompanied by an increase in levels of the L-type Ca(2+)-channel, which is implicated in pathological hypertrophy. When Tm180 mice were crossed with a PMCA4-null line, loss of PMCA4 caused the abrogation of hypertrophy in Tm180/PMCA4-null double mutant mice. RT-PCR analysis of Tm180/PMCA4-null hearts revealed blunting of the fetal program and reversion of pro-fibrotic Col1a1 and Col3a1 gene expression to wild-type levels. This was accompanied by evidence of reduced L-type Ca(2+)-channel expression, and diminished calcineurin activity. Expression of the metabolic substrate transporters glucose transporter 4 and carnitine palmitoyltransferase 1b was preserved and Tm180-related changes in mRNA levels of various contractile stress-related proteins including the cardiac ankyrin protein CARP and the N2B isoform of titin were reversed in Tm180/PMCA4-null hearts. cGMP levels were increased and phosphorylation of vasodilator-stimulated phosphoprotein was elevated in Tm180/PMCA4-null hearts. These changes were associated with a sharp reduction in left ventricular end-diastolic pressure in Tm180/PMCA4-null hearts, which occurred despite persistence of Tm180-related impairment of relaxation dynamics. These results reveal a novel and specific role for PMCA4 in the Tm180 hypertrophic phenotype, with the "protective" effects of PMCA4 deficiency encompassing multiple determinants of HCM-related hypertrophy.


Assuntos
Cardiomiopatia Hipertrófica/enzimologia , ATPases Transportadoras de Cálcio da Membrana Plasmática/genética , Tropomiosina/genética , Animais , Cardiomiopatia Hipertrófica/genética , Modelos Animais de Doenças , Expressão Gênica , Técnicas de Inativação de Genes , Frequência Cardíaca , Masculino , Camundongos Knockout , Miocárdio/metabolismo , Miocárdio/patologia , ATPases Transportadoras de Cálcio da Membrana Plasmática/metabolismo , Tropomiosina/metabolismo , Pressão Ventricular
7.
Nat Commun ; 5: 4241, 2014 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-24980141

RESUMO

The Rag family proteins are Ras-like small GTPases that have a critical role in amino-acid-stimulated mTORC1 activation by recruiting mTORC1 to lysosome. Despite progress in the mechanistic understanding of Rag GTPases in mTORC1 activation, little is known about the physiological function of Rag GTPases in vivo. Here we show that loss of RagA and RagB (RagA/B) in cardiomyocytes results in hypertrophic cardiomyopathy and phenocopies lysosomal storage diseases, although mTORC1 activity is not substantially impaired in vivo. We demonstrate that despite upregulation of lysosomal protein expression by constitutive activation of the transcription factor EB (TFEB) in RagA/B knockout mouse embryonic fibroblasts, lysosomal acidification is compromised owing to decreased v-ATPase level in the lysosome fraction. Our study uncovers RagA/B GTPases as key regulators of lysosomal function and cardiac protection.


Assuntos
Cardiomiopatia Hipertrófica/enzimologia , Lisossomos/enzimologia , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Animais , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/prevenção & controle , Feminino , Humanos , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Monoméricas de Ligação ao GTP/genética , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Miócitos Cardíacos/enzimologia , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismo
8.
J Intern Med ; 276(6): 543-59, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24824502

RESUMO

The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that regulates cellular and whole-body energy balance. A recently reported crystal structure has illuminated the complex regulatory mechanisms by which AMP and ADP cause activation of AMPK, involving phosphorylation by the upstream kinase LKB1. Once activated by falling cellular energy status, AMPK activates catabolic pathways that generate ATP whilst inhibiting anabolic pathways and other cellular processes that consume ATP. A role of AMPK is implicated in many human diseases. Mutations in the γ2 subunit cause heart disease due to excessive glycogen storage in cardiac myocytes, leading to ventricular pre-excitation. AMPK-activating drugs reverse many of the metabolic defects associated with insulin resistance, and recent findings suggest that the insulin-sensitizing effects of the widely used antidiabetic drug metformin are mediated by AMPK. The upstream kinase LKB1 is a tumour suppressor, and AMPK may exert many of its antitumour effects. AMPK activation promotes the oxidative metabolism typical of quiescent cells, rather than the aerobic glycolysis observed in tumour cells and cells involved in inflammation, explaining in part why AMPK activators have both antitumour and anti-inflammatory effects. Salicylate (the major in vivo metabolite of aspirin) activates AMPK, and this could be responsible for at least some of the anticancer and anti-inflammatory effects of aspirin. In addition to metformin and salicylates, novel drugs that modulate AMPK are likely to enter clinical trials soon. Finally, AMPK may be involved in viral infection: downregulation of AMPK during hepatitis C virus infection appears to be essential for efficient viral replication.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Metabolismo Energético , Proteínas Quinases Ativadas por AMP/química , Proteínas Quinases Ativadas por AMP/efeitos dos fármacos , Proteínas Quinases Ativadas por AMP/genética , Nucleotídeos de Adenina/metabolismo , Canais de Cálcio/metabolismo , Cardiomiopatia Hipertrófica/enzimologia , Diabetes Mellitus Tipo 2/enzimologia , Humanos , Inflamação/enzimologia , Estrutura Molecular , Mutação , Neoplasias/enzimologia , Viroses/enzimologia
9.
PLoS One ; 8(5): e63309, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23691019

RESUMO

BACKGROUND: Genetic factors in the pathogenesis of cardiomyopathies have received a lot attention during the past two decades. Angiotensin I converting enzyme (ACE) insertion/deletion (I/D) polymorphisms were found to be associated with cardiomyopathies. However, the previous results were inconsistent. The current meta-analysis aims to examine the association of ACE I/D polymorphisms and dilated cardiomyopathy (DCM) or hypertrophic cardiomyopathy (HCM). METHODS: Eight studies on DCM (1387 controls and 977 patients) and eight studies on HCM (1055 controls and 827 patients) were included in this meta-analysis. RESULTS: The overall data showed no significant association between ACE I/D polymorphism and DCM risk. Further subgroup analysis by ethnicity also did not find a significantly increased risk for D allele carriers among East Asians and Europeans. However, the overall analysis suggested that the D allele carriers might be associated with increased risk of HCM (DD/ID vs. II: OR = 1.69, 95% CI 1.04-2.74, P = 0.03). CONCLUSION: In summary, the meta-analysis indicated that certain ACE I/D polymorphism might be associated with HCM but not DCM susceptibility. Given the limited sample sizes, further large multicenter case-control investigation is needed.


Assuntos
Cardiomiopatia Dilatada/genética , Cardiomiopatia Hipertrófica/genética , Predisposição Genética para Doença/genética , Mutação INDEL , Peptidil Dipeptidase A/genética , Polimorfismo Genético , Cardiomiopatia Dilatada/enzimologia , Cardiomiopatia Hipertrófica/enzimologia , Humanos
10.
Arch Biochem Biophys ; 535(1): 39-48, 2013 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-23352598

RESUMO

The pathological progression of hypertrophic cardiomyopathy (HCM) is sexually dimorphic such that male HCM mice develop phenotypic indicators of cardiac disease well before female HCM mice. Here, we hypothesized that alterations in myofilament function underlies, in part, this sex dimorphism in HCM disease development. Firstly, 10-12month female HCM (harboring a mutant [R403Q] myosin heavy chain) mice presented with proportionately larger hearts than male HCM mice. Next, we determined Ca(2+)-sensitive tension development in demembranated cardiac trabeculae excised from 10-12month female and male HCM mice. Whereas HCM did not impact Ca(2+)-sensitive tension development in male trabeculae, female HCM trabeculae were more sensitive to Ca(2+) than wild-type (WT) counterparts and both WT and HCM males. We hypothesized that the underlying cause of this sex difference in Ca(2+)-sensitive tension development was due to changes in Ca(2+) handling and sarcomeric proteins, including expression of SR Ca(2+) ATPase (2a) (SERCA2a), ß-myosin heavy chain (ß-MyHC) and post-translational modifications of myofilament proteins. Female HCM hearts showed an elevation of SERCA2a and ß-MyHC protein whereas male HCM hearts showed a similar elevation of ß-MyHC protein but a reduced level of cardiac troponin T (cTnT) phosphorylation. We also measured the distribution of cardiac troponin I (cTnI) phosphospecies using phosphate-affinity SDS-PAGE. The distribution of cTnI phosphospecies depended on sex and HCM. In conclusion, female and male HCM mice display sex dimorphic myofilament function that is accompanied by a sex- and HCM-dependent distribution of sarcomeric proteins and cTnI phosphospecies.


Assuntos
Cardiomiopatia Hipertrófica/metabolismo , Miofibrilas/fisiologia , Troponina I/metabolismo , Animais , Cálcio/metabolismo , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/patologia , Eletroforese em Gel de Poliacrilamida , Feminino , Ventrículos do Coração/metabolismo , Ventrículos do Coração/patologia , Masculino , Camundongos , Tono Muscular , Mutação , Miofibrilas/genética , Miofibrilas/metabolismo , Cadeias Pesadas de Miosina/metabolismo , Cadeias Leves de Miosina/metabolismo , Fosforilação , Processamento de Proteína Pós-Traducional , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Fatores Sexuais , Troponina T/metabolismo , Miosinas Ventriculares/genética , Miosinas Ventriculares/metabolismo
11.
Cardiovasc Res ; 97(1): 44-54, 2013 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-22987565

RESUMO

AIMS: The role of calcineurin protein phosphatase 2B (PP2B) in the pathogenesis of human hypertrophic cardiomyopathy (HCM) remains unsettled. We determined potential involvement of calcineurin in the pathogenesis of HCM caused by mutations in myozenin 2 (MYOZ2), an inhibitor of calcineurin. METHODS AND RESULTS: We generated multiple lines of transgenic mice expressing either Flag-tagged wild-type (WT) (MYOZ2(WT)) or mutant MYOZ2(S48P) and MYOZ2(I246M), identified in families with HCM, in the heart. To mimic the human genotype, we generated bigenic mice expressing WT and mutant MYOZ2 in the background of hemizygous endogenous MYOZ2 (Myoz2(+/-)). Transgene proteins constituted 15-48% of the total MYOZ2 protein in the heart. Mutant MYOZ2 mice showed molecular, cellular, and gross cardiac hypertrophy, preserved systolic function, and interstitial fibrosis. Immunofluorescence staining showed co-localization of WT and mutant MYOZ2 proteins with α-actinin at the Z disks. Electron microscopy showed disrupted and mal-aligned Z disks in the mutant mice. Cardiac calcineurin activity, determined by quantifying Rcan1.4 mRNA and protein levels, luciferase activity in triple transgenic Myoz2(+/-):NFATc-Luc:MYOZ2(I246M) and Myoz2(+/-):NFATc-Luc:MYOZ2(WT) mice, and NFATc transcriptional activity assay, was unchanged in the mutant transgenic mice. However, levels of phospho-ERK1/2 and JNK54/46 were altered in the transgenic mice. Likewise, lentiviral-mediated expression of the MYOZ2(I246M) did not affect RCAN1.4 and calcineurin (PPP3CB) protein levels. CONCLUSIONS: Thus, the cardiac phenotype in HCM caused by MYOZ2 mutations might be independent of calcineurin activity in the heart. Z disk abnormalities might provide the stimulus for the induction of cardiac hypertrophy caused by MYOZ2 mutations.


Assuntos
Calcineurina/metabolismo , Cardiomiopatia Hipertrófica/genética , Proteínas de Transporte/genética , Proteínas Musculares/genética , Mutação , Miocárdio/enzimologia , Animais , Proteínas de Ligação ao Cálcio , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/patologia , Cardiomiopatia Hipertrófica/fisiopatologia , Proteínas de Transporte/metabolismo , Células Cultivadas , Modelos Animais de Doenças , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fibrose , Imunofluorescência , Genes Reporter , Predisposição Genética para Doença , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Proteínas dos Microfilamentos , Microscopia Eletrônica , Proteínas Musculares/deficiência , Proteínas Musculares/metabolismo , Miocárdio/ultraestrutura , Fatores de Transcrição NFATC/genética , Fatores de Transcrição NFATC/metabolismo , Fenótipo , Fosforilação , RNA Mensageiro/metabolismo , Ratos , Transfecção
12.
Rev. chil. cardiol ; 32(3): 233-239, 2013. ilus
Artigo em Espanhol | LILACS | ID: lil-705227

RESUMO

El Síndrome de Sengers es una enfermedad mitocondrial autosómica recesiva, producida por mutación del gen de la Acil-Glicerol Kinasa (AGK), recientemente descubierto. Se caracteriza por cataratas congénitas bilaterales, miocardiopatía hipertrófica y acidosis láctica. Puede tener miopatía esquelética leve, intolerancia al ejercicio y desarrollo mental normal. Los pacientes fallecen tempranamente debido a falla cardíaca. Dada la alta letalidad, lo infrecuente de este síndrome y la presencia de un diagnóstico confirmado, se presenta el caso clínico de 2 hermanos chilenos, fallecidos por la enfermedad, que se presentaron con el cuadro característico de cataratas congénitas bilaterales, miocardiopa-tía hipertrófica y acidosis láctica. El mayor, se operó las cataratas a los 4 meses de edad y falleció a la edad de 13 meses debido a falla cardíaca severa refractaria y falla orgánica múltiple, descompensado por una infección respiratoria. El menor se diagnosticó a los 3 meses de edad y se le confirmó la mutación del gen de AGK en Alemania. Se decidió no operarlo de las cataratas dado el mal pronóstico vital. Presentó progresión de la miocardiopatía hipertrófica y falleció súbitamente a los 8 meses de edad.


Senger's Syndrome is a recessive autosomal mitochondrial disease due to a recently discovered mutation of the Acyl-Glycerol Kinase (AGK) gen,. It is characterized by congenital bilateral cataracts, progressive hypertrophic cardiomyopathy and lactic acidosis. It may present skeletal myopathy, exercise intolerance and usually normal mental development. Patients die early in life due to heart failure. The clinical cases of two brothers with a confirmed diagnosis of Senger's syndrome are reported. The older brother was operated on for cataracts at the age of 4 months and he died when he was 13 months old due to severe refractory heart failure and multi-organ failure, decompensated by a respiratory infection. The younger brother was diagnosed at 3 month of age and the AGK gene mutation was confirmed in Germany. Cataracts were not operated on due to the the patient's extremely poor prognosis. He had progressive hypertrophic cardiomyopathy and died suddenly at 8 month of age.


Assuntos
Humanos , Masculino , Recém-Nascido , Lactente , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/genética , Doenças Mitocondriais , Fosfotransferases (Aceptor do Grupo Álcool) , Acidose Láctica , Cardiomiopatias , Catarata/congênito , Mutação
13.
Drug Metab Dispos ; 40(11): 2126-35, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22867862

RESUMO

Doxorubicin [(DOX) Adriamycin] is an effective anticancer agent whose major limiting side effect is cardiotoxicity. This cardiotoxicity is predicted only by the cumulative dose of DOX where the clinical situation involves chronic drug administration. Therefore, we investigate the effect of chronic DOX cardiotoxicity on expression of the cardiac cytochrome P450 (P450) enzymes and arachidonic acid (AA) metabolism in male Sprague-Dawley (SD) rats. The chronic toxicity was induced by multiple intraperitoneal injections for a cumulative dose of 15 mg/kg divided into six injections within 2 weeks. After 14 days of the last injection, the heart, liver, and kidney were harvested, and the expression of different genes was determined by real-time polymerase chain reaction. In addition, microsomal protein from the heart was prepared and incubated with AA. Thereafter, different AA metabolites were analyzed by liquid chromatography-electrospray ionization-mass spectrometry. The chronic DOX cardiotoxicity significantly induced gene expression of hypertrophic markers, apoptotic markers, CYP2E1, CYP4A3, CYP4F1, CYP4F5, and soluble epoxide hydrolase (sEH) enzyme, which was accompanied by an increase in the activity of P450 ω-hydroxylases and sEH. In addition, both the sEH inhibitor, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid, and the ω-hydroxylase inhibitor, N-hydroxy-N'-(4-butyl-2-methylphenyl)-formamidine (HET0016), significantly prevented the DOX-mediated induction of the hypertrophic markers in the cardiac-derived H9c2 cells, which further confirms the role of these enzymes in DOX cardiotoxicity. Furthermore, gene expression of P450 and sEH was altered in an organ-specific manner. As a result, the chronic DOX administration leads to an imbalance between P450-mediated cardiotoxic and cardioprotective pathways. Therefore, P450 ω-hydroxylases and sEH might be considered as novel targets to prevent and/or treat DOX cardiotoxicity.


Assuntos
Ácido Araquidônico/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Doxorrubicina/toxicidade , Coração/efeitos dos fármacos , Miocárdio/metabolismo , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Fator Natriurético Atrial/genética , Fator Natriurético Atrial/metabolismo , Biomarcadores/metabolismo , Cardiomiopatia Hipertrófica/induzido quimicamente , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/metabolismo , Células Cultivadas , Citocromo P-450 CYP4A/genética , Citocromo P-450 CYP4A/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Epóxido Hidrolases/genética , Epóxido Hidrolases/metabolismo , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/genética , Inflamação/induzido quimicamente , Inflamação/enzimologia , Inflamação/genética , Inflamação/metabolismo , Rim/efeitos dos fármacos , Rim/enzimologia , Rim/metabolismo , Fígado/efeitos dos fármacos , Fígado/enzimologia , Fígado/metabolismo , Masculino , Microssomos/efeitos dos fármacos , Microssomos/enzimologia , Microssomos/metabolismo , Miocárdio/enzimologia , Peptídeo Natriurético Encefálico/genética , Peptídeo Natriurético Encefálico/metabolismo , RNA Mensageiro/genética , Ratos , Ratos Sprague-Dawley
14.
Orphanet J Rare Dis ; 7: 35, 2012 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-22676651

RESUMO

BACKGROUND: Pompe disease (Glycogen storage disease type II, GSD II, acid alpha-glucosidase deficiency, acid maltase deficiency, OMIM # 232300) is an autosomal-recessive lysosomal storage disorder due to a deficiency of acid alpha-glucosidase (GAA, acid maltase, EC 3.2.1.20, Swiss-Prot P10253). Clinical manifestations are dominated by progressive weakness of skeletal muscle throughout the clinical spectrum. In addition, the classic infantile form is characterised by hypertrophic cardiomyopathy. METHODS: In a cross-sectional single-centre study we clinically assessed 3 patients with classic infantile Pompe disease and 39 patients with non-classic presentations, measured their acid alpha-glucosidase activities and analysed their GAA genes. RESULTS: Classic infantile patients had nearly absent residual enzyme activities and a typical clinical course with hypertrophic cardiomyopathy until the beginning of therapy. The disease manifestations in non-classic patients were heterogeneous. There was a broad variability in the decline of locomotive and respiratory function. The age of onset ranged from birth to late adulthood and correlated with enzyme activities. Molecular analysis revealed as many as 33 different mutations, 14 of which are novel. All classic infantile patients had two severe mutations. The most common mutation in the non-classic group was c.-32-13T>G. It was associated with a milder course in this subgroup. CONCLUSIONS: Disease manifestation strongly correlates with the nature of the GAA mutations, while the variable progression in non-classic Pompe disease is likely to be explained by yet unknown modifying factors. This study provides the first comprehensive dataset on the clinical course and the mutational spectrum of Pompe disease in Germany.


Assuntos
Predisposição Genética para Doença , Doença de Depósito de Glicogênio Tipo II/genética , Doença de Depósito de Glicogênio Tipo II/fisiopatologia , Mutação , alfa-Glucosidases/genética , Adolescente , Adulto , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/fisiopatologia , Cardiomiopatia Hipertrófica/terapia , Estudos Transversais , Terapia de Reposição de Enzimas , Feminino , Estudos de Associação Genética , Alemanha , Doença de Depósito de Glicogênio Tipo II/enzimologia , Doença de Depósito de Glicogênio Tipo II/terapia , Humanos , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/fisiopatologia , Adulto Jovem
15.
Circ Heart Fail ; 5(4): 462-6, 2012 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-22628530

RESUMO

BACKGROUND: Myocardial fibrosis is a hallmark of hypertrophic cardiomyopathy (HCM) and a risk factor for ventricular arrhythmia. Fibrosis can be reflected in circulating matrix remodeling protein concentrations. We explored differences in circulating markers of extracellular matrix turnover between young HCM patients with versus without history of serious arrhythmia. METHODS AND RESULTS: Using multiplexed and single ELISA, matrix metalloproteinases (MMPs) 1, 2, 3, and 9; tissue inhibitor of metalloproteinases (TIMPs) 1, 2, and 4; and collagen I carboxyterminal peptide (CICP) were measured in plasma from 45 young HCM patients (80% male patients; median age, 17 years [interquartile range, 15-20]). Participants were grouped into serious ventricular arrhythmia history (VA) versus no ventricular arrhythmia history (NoVA). Differences in MMPs between groups were examined nonparametrically. Relationships between MMPs and ventricular arrhythmia were assessed with linear regression, adjusted for interventricular septal thickness, family history of sudden death, abnormal exercise blood pressure, and implantable cardioverter-defibrillator (ICD). In post hoc sensitivity analysis, age was substituted for ICD. The 14 VA patients were older than 31 NoVA patients (median, 19 versus 17 years; P=0.03). All 14 VA and 12 NoVA patients had an ICD. MMP3 concentration was significantly higher in the VA group (VA median, 12.9 µg/mL [interquartile range, 5.7-16.7 µg/mL] versus NoVA, 5.8 µg/mL [interquartile range, 3.7-10.0 µg/mL]; P=0.01). On multivariable analysis, VA was independently associated with increasing MMP3 (standardized ß, 0.37; P=0.01). Post hoc adjustment for age attenuated this association. CONCLUSIONS: Circulating MMP3 may be a marker of ventricular arrhythmia in adolescent patients with HCM. Because of our role as pediatric providers, we cannot exclude age-related confounding.


Assuntos
Cardiomiopatia Hipertrófica/enzimologia , Metaloproteinase 3 da Matriz/sangue , Miocárdio/enzimologia , Taquicardia Ventricular/enzimologia , Fibrilação Ventricular/enzimologia , Adolescente , Fatores Etários , Biomarcadores/sangue , Boston , Cardiomiopatia Hipertrófica/sangue , Cardiomiopatia Hipertrófica/complicações , Cardiomiopatia Hipertrófica/patologia , Estudos Transversais , Ensaio de Imunoadsorção Enzimática , Feminino , Fibrose , Humanos , Modelos Lineares , Masculino , Metaloproteinase 1 da Matriz/sangue , Metaloproteinase 2 da Matriz/sangue , Metaloproteinase 9 da Matriz/sangue , Análise Multivariada , Miocárdio/patologia , Medição de Risco , Fatores de Risco , Taquicardia Ventricular/sangue , Taquicardia Ventricular/etiologia , Taquicardia Ventricular/patologia , Inibidores Teciduais de Metaloproteinases/sangue , Fibrilação Ventricular/sangue , Fibrilação Ventricular/etiologia , Fibrilação Ventricular/patologia , Adulto Jovem
16.
Biochemistry ; 51(17): 3614-21, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22489623

RESUMO

The objective of this work was to investigate the effect of hypertrophic cardiomyopathy-linked A8V and E134D mutations in cardiac troponin C (cTnC) on the response of reconstituted thin filaments to calcium upon phosphorylation of cardiac troponin I (cTnI) by protein kinase A. The phosphorylation of cTnI at protein kinase A sites was mimicked by the S22D/S23D double mutation in cTnI. Our results demonstrate that the A8V and E134D mutations had no effect on the extent of calcium desensitization of reconstituted thin filaments induced by cTnI pseudophosphorylation. However, the A8V mutation enhanced the effect of cTnI pseudophosphorylation on the rate of dissociation of calcium from reconstituted thin filaments and on the calcium dependence of actomyosin ATPase. Consequently, while the A8V mutation still led to a slower rate of dissociation of calcium from reconstituted thin filaments upon pseudophosphorylation of cTnI, the ability of the A8V mutation to decrease the rate of calcium dissociation was weakened. In addition, the ability of the A8V mutation to sensitize actomyosin ATPase to calcium was weakened after cTnI was replaced by the phosphorylation mimetic of cTnI. Consistent with the hypothesis that the E134D mutation is benign, it exerted a minor to no effect on the rate of dissociation of calcium from reconstituted thin filaments or on the calcium sensitivity of actomyosin ATPase, regardless of the cTnI phosphorylation status. In conclusion, our study enhances our understanding of how cardiomyopathy-linked cTnC mutations affect the response of reconstituted thin filaments to calcium upon cTnI phosphorylation.


Assuntos
Citoesqueleto de Actina/genética , Cálcio/química , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/metabolismo , Troponina C/genética , Troponina I/metabolismo , Substituição de Aminoácidos/genética , Animais , Cálcio/metabolismo , Cardiomiopatia Hipertrófica/enzimologia , Bovinos , Proteínas Quinases Dependentes de AMP Cíclico/química , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Humanos , Mutagênese Sítio-Dirigida , Fosforilação/genética , Coelhos , Troponina C/metabolismo , Troponina I/antagonistas & inibidores , Troponina I/genética
17.
Am J Physiol Heart Circ Physiol ; 302(1): H231-43, 2012 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-22058153

RESUMO

The identification of mutations in PTPN11 (encoding the protein tyrosine phosphatase Shp2) in families with congenital heart disease has facilitated mechanistic studies of various cardiovascular defects. However, the roles of normal and mutant Shp2 in the developing heart are still poorly understood. Furthermore, it remains unclear how Shp2 loss-of-function (LOF) mutations cause LEOPARD Syndrome (also termed Noonan Syndrome with multiple lentigines), which is characterized by congenital heart defects such as pulmonary valve stenosis and hypertrophic cardiomyopathy (HCM). In normal hearts, Shp2 controls cardiomyocyte size by regulating signaling through protein kinase B (Akt) and mammalian target of rapamycin (mTOR). We hypothesized that Shp2 LOF mutations dysregulate this pathway, resulting in HCM. For our studies, we chose the Shp2 mutation Q510E, a dominant-negative LOF mutation associated with severe early onset HCM. Newborn mice with cardiomyocyte-specific overexpression of Q510E-Shp2 starting before birth displayed increased cardiomyocyte sizes, heart-to-body weight ratios, interventricular septum thickness, and cardiomyocyte disarray. In 3-mo-old hearts, interstitial fibrosis was detected. Echocardiographically, ventricular walls were thickened and contractile function was depressed. In ventricular tissue samples, signaling through Akt/mTOR was hyperactivated, indicating that the presence of Q510E-Shp2 led to upregulation of this pathway. Importantly, rapamycin treatment started shortly after birth rescued the Q510E-Shp2-induced phenotype in vivo. If rapamycin was started at 6 wk of age, HCM was also ameliorated. We also generated a second mouse model in which cardiomyocyte-specific Q510E-Shp2 overexpression started after birth. In contrast to the first model, these mice did not develop HCM. In summary, our studies establish a role for mTOR signaling in HCM caused by Q510E-Shp2. Q510E-Shp2 overexpression in the cardiomyocyte population alone was sufficient to induce the phenotype. Furthermore, the pathomechanism was triggered pre- but not postnatally. However, postnatal rapamycin treatment could still reverse already established HCM, which may have important therapeutic implications.


Assuntos
Cardiomiopatia Hipertrófica/enzimologia , Mutação , Miócitos Cardíacos/enzimologia , Proteína Tirosina Fosfatase não Receptora Tipo 11/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Fatores Etários , Envelhecimento/genética , Envelhecimento/metabolismo , Animais , Animais Recém-Nascidos , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/patologia , Cardiomiopatia Hipertrófica/fisiopatologia , Cardiomiopatia Hipertrófica/prevenção & controle , Tamanho Celular , Células Cultivadas , Modelos Animais de Doenças , Fibrose , Camundongos , Camundongos Transgênicos , Mutagênese Sítio-Dirigida , Contração Miocárdica , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/patologia , Inibidores de Proteínas Quinases/farmacologia , Proteína Tirosina Fosfatase não Receptora Tipo 11/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologia , Serina-Treonina Quinases TOR/antagonistas & inibidores , Transfecção , Função Ventricular Esquerda
18.
Hum Mol Genet ; 21(1): 85-100, 2012 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-21945886

RESUMO

The genetic and epigenetic factors underlying the variable penetrance of homoplasmic mitochondrial DNA mutations are poorly understood. We investigated a 16-year-old patient with hypertrophic cardiomyopathy harboring a homoplasmic m.4277T>C mutation in the mt-tRNA(Ile) (MTTI) gene. Skeletal muscle showed multiple respiratory chain enzyme abnormalities and a decreased steady-state level of the mutated mt-tRNA(Ile). Transmitochondrial cybrids grown on galactose medium demonstrated a functional effect of this mutation on cell viability, confirming pathogenicity. These findings were reproduced in transmitochondrial cybrids, harboring a previously described homoplasmic m.4300A>G MTTI mutation. The pathogenic role of the m.4277T>C mutation may be ascribed to misfolding of the mt-tRNA molecule, as demonstrated by the altered electrophoretic migration of the mutated mt-tRNA. Indeed, structure and sequence analyses suggest that thymidine at position 4277 of mt-tRNA(Ile) is involved in a conserved tertiary interaction with thymidine at position 4306. Interestingly, the mutation showed variable penetrance within family members, with skeletal muscle from the patient's clinically unaffected mother demonstrating normal muscle respiratory chain activities and steady-state levels of mt-tRNA(Ile), while homoplasmic for the m.4277T>C mutation. Analysis of mitochondrial isoleucyl-tRNA synthetase revealed significantly higher expression levels in skeletal muscle and fibroblasts of the unaffected mother when compared with the proband, while the transient over-expression of the IARS2 gene in patient transmitochondrial cybrids improved cell viability. This is the first observation that constitutively high levels of aminoacyl-tRNA synthetases (aaRSs) in human tissues prevent the phenotypic expression of a homoplasmic mt-tRNA point mutation. These findings extend previous observations on aaRSs therapeutic effects in yeast and human.


Assuntos
Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/genética , Isoleucina-tRNA Ligase/metabolismo , Penetrância , Mutação Puntual , RNA de Transferência de Isoleucina/genética , Adolescente , Sequência de Bases , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Humanos , Isoleucina-tRNA Ligase/genética , Masculino , Mitocôndrias/genética , Mitocôndrias/metabolismo , Dados de Sequência Molecular , RNA de Transferência de Isoleucina/metabolismo
19.
Acta Myol ; 30(1): 46-8, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21842595

RESUMO

MyoAdenylate Deaminase Deficiency (MADD) is a relatively common metabolic disorder of the skeletal muscle. Patients with MADD usually show an impaired bioenergetic production and a clinical spectrum with either exercise-induced muscle pain, fatigue and/or rhabdomyolysis. Left ventricular hypertrophy as well as other types of cardiac involvement have been reported in patients with primary MADD. We describe herein a case of a 61-year-old woman with biochemical and genetic evidence of Myo-Adenylate Deaminase deficiency, in whom we found a right ventricular hypertrophic cardiomyopathy leading to severe outflow tract dynamic obstruction.


Assuntos
AMP Desaminase/deficiência , Cardiomiopatia Hipertrófica/enzimologia , Hipertrofia Ventricular Direita/enzimologia , Obstrução do Fluxo Ventricular Externo/etiologia , Cardiomiopatia Hipertrófica/diagnóstico por imagem , Cardiomiopatia Hipertrófica/fisiopatologia , Ecocardiografia , Eletrocardiografia , Feminino , Humanos , Hipertrofia Ventricular Direita/complicações , Hipertrofia Ventricular Direita/diagnóstico por imagem , Hipertrofia Ventricular Direita/fisiopatologia , Pessoa de Meia-Idade
20.
Circulation ; 123(21): 2392-403, 2011 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-21576649

RESUMO

BACKGROUND: Cardiac hypertrophy is characterized by transcriptional reprogramming of fetal gene expression, and histone deacetylases (HDACs) are tightly linked to the regulation of those genes. We previously demonstrated that activation of HDAC2, 1 of the class I HDACs, mediates hypertrophy. Here, we show that casein kinase-2α1 (CK2α1)-dependent phosphorylation of HDAC2 S394 is required for the development of cardiac hypertrophy. METHODS AND RESULTS: Hypertrophic stimuli phosphorylated HDAC2 S394, which was necessary for its enzymatic activation, and therefore the development of hypertrophic phenotypes in rat neonatal cardiomyocytes or in isoproterenol-administered mice hearts. Transgenic mice overexpressing HDAC2 wild type exhibited cardiac hypertrophy, whereas those expressing phosphorylation-resistant HDAC2 S394A did not. Compared with that in age-matched normal human hearts, phosphorylation of HDAC2 S394 was dramatically increased in patients with hypertrophic cardiomyopathy. Hypertrophy-induced phosphorylation of HDAC2 S394 and its enzymatic activity were completely blocked either by CK2 blockers or by CK2α1 short interfering RNA. Hypertrophic stimuli led CK2α1 to be activated, and its chemical inhibitors blocked hypertrophy in both phenylephrine-treated cardiomyocytes and isoproterenol-administered mice. CK2α1-transgenic mice developed hypertrophy, which was attenuated by administration of trichostatin A, an HDAC inhibitor. Overexpression of CK2α1 caused hypertrophy in cardiomyocytes, whereas chemical inhibitors of both CK2 and HDAC as well as HDAC2 S394A blunted it. Hypertrophy in CK2α1-transgenic mice was exaggerated by crossing these mice with wild-type-HDAC2-overexpressing mice. By contrast, however, it was blocked when CK2α1-transgenic mice were crossed with HDAC2 S394A-transgenic mice. CONCLUSIONS: We have demonstrated a novel mechanism in the development of cardiac hypertrophy by which CK2 activates HDAC2 via phosphorylating HDAC2 S394.


Assuntos
Cardiomegalia/enzimologia , Caseína Quinase II/metabolismo , Ventrículos do Coração/enzimologia , Histona Desacetilase 2/metabolismo , Serina/metabolismo , Alanina/genética , Animais , Cardiomegalia/genética , Cardiomegalia/patologia , Cardiomiopatia Hipertrófica/enzimologia , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/patologia , Caseína Quinase II/genética , Ativação Enzimática/genética , Ventrículos do Coração/patologia , Histona Desacetilase 2/biossíntese , Histona Desacetilase 2/genética , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fosforilação/genética , Serina/genética
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